Ch 20 + 23 Objectives Flashcards
(397 cards)
1
Q
What is the difference between drug allergies and adverse reactions?
A
Drug allergies are true allergies that are absolute contraindications to drug use, while adverse reactions, such as opioid or antibiotic-related GI side effects, do not qualify as true allergies.
2
Q
What are common anesthesia-related allergens?
A
Common anesthesia-related allergens include neuromuscular blocking agents (NMBAs) and antibiotics.
3
Q
What percentage of intraoperative anaphylaxis cases are linked to latex?
A
Up to 20% of intraoperative anaphylaxis cases are linked to latex.
4
Q
Who are considered high-risk patients for latex sensitivity?
A
High-risk patients include those with chronic latex exposure, spina bifida, history of multiple surgeries, previous reactions to latex products, and food allergies to latex-associated foods.
5
Q
What precautions should be taken for latex-allergic patients?
A
Precautions include scheduling as the first case of the day, ensuring a no-latex environment in the OR, and conducting preoperative skin-prick or in-vitro testing if necessary.
6
Q
How does smoking affect perioperative complications?
A
Smoking increases perioperative complications, including wound healing and pulmonary risks.
7
Q
What are the risks associated with heavy smoking?
A
Heavy smokers have a 2-4x increased risk of coronary heart disease and stroke, and smoking increases postoperative pulmonary complications nearly 6-fold.
8
Q
What is the impact of short-term smoking cessation before surgery?
A
Short-term cessation (12-48 hours pre-op) improves carbon monoxide levels, blood pressure, and heart rate but does not reduce pulmonary risks.
9
Q
What are the risks of chronic alcohol use in the perioperative setting?
A
Chronic alcohol use increases anesthetic requirements due to tolerance and raises the risk of postoperative complications, including arrhythmias and infections.
10
Q
What is the CAGE questionnaire used for?
A
The CAGE questionnaire is used to assess risk for alcohol dependence and withdrawal.
11
Q
What are the symptoms of alcohol withdrawal?
A
Symptoms include tremors, tachycardia, hypertension, insomnia, anxiety, nausea, restlessness, hallucinations, agitation, and seizures.
12
Q
What should be done for patients with a history of alcohol withdrawal?
A
Preoperative benzodiazepines may be needed to prevent withdrawal.
13
Q
What complications can arise from illicit drug use during anesthesia?
A
Illicit drug use complicates anesthesia due to drug interactions, tolerance, and withdrawal risks.
14
Q
What are the risks associated with cocaine and methamphetamines?
A
Cocaine and methamphetamines can cause severe hypertension, arrhythmias, and myocardial ischemia, and elective surgery should be delayed if used recently.
15
Q
How does marijuana affect anesthesia?
A
Marijuana increases anesthetic and sedative requirements and may cause tachycardia, anxiety, and hypotension.
16
Q
What are the effects of chronic opioid use?
A
Chronic opioid users have higher pain thresholds and require increased postoperative analgesia.
High risk of opioid-induced hyperalgesia.
17
Q
What is recommended for pain management in opioid users?
A
Multimodal analgesia (NSAIDs, ketamine, regional anesthesia) is recommended.
18
Q
What should be discussed when using opioid substitution therapy?
A
Discuss withdrawal risk and pain management strategies.
19
Q
What are the unpredictable effects of hallucinogens?
A
They can cause unpredictable cardiovascular and psychological effects.
Risk of hypertensive crisis, serotonin syndrome, postoperative delirium.
20
Q
What are the risks associated with inhalants?
A
Risk of sudden cardiac arrest due to myocardial sensitization.
Long-term use can cause neuropathy and cognitive impairment.
21
Q
What are physical exam findings suggestive of substance abuse?
A
Track marks, skin abscesses, venous thrombosis (IV drug use).
22
Q
What does constricted pupils indicate?
A
Constricted pupils indicate opioid use.
23
Q
What do dilated pupils indicate?
A
Dilated pupils indicate cocaine or amphetamines use.
24
Q
What does nystagmus indicate?
A
Nystagmus indicates PCP use.
25
What does nasal perforation indicate?
Nasal perforation indicates cocaine abuse.
26
What does poor dental health indicate?
Poor dental health indicates methamphetamine use.
27
What does malnutrition indicate?
Malnutrition indicates chronic amphetamine use.
28
What are common medications for opioid abstinence?
Methadone (full opioid agonist), Buprenorphine (partial agonist, e.g., Suboxone), Naltrexone (opioid antagonist, used for both opioid and alcohol dependence).
29
What do opioid-tolerant patients require for pain control?
Opioid-tolerant patients require higher doses for pain control.
30
What should be considered for multimodal pain management?
Consider regional anesthesia, NSAIDs, ketamine, IV lidocaine, clonidine, COX-2 inhibitors.
31
How should methadone and buprenorphine be managed?
Methadone and buprenorphine continuation or withdrawal should be managed in collaboration with addiction specialists.
32
Why is a thorough social history important?
A thorough social history allows for early intervention and risk reduction.
33
How should patients be approached about substance use?
Patients may not disclose substance use unless specifically asked in a professional, nonjudgmental manner.
34
What is the purpose of assessment in anesthesia planning?
Assessment helps in tailoring anesthesia plans and educating patients on the risks of substance use in the surgical setting.
35
What are anabolic steroids used for?
Self-administered to increase muscle mass, strength, and athletic performance.
36
What are the risks of long-term anabolic steroid use?
Long-term use leads to significant endocrine, cardiovascular, and hepatic dysfunction.
37
Signs and symptoms of Cannabis (Marijuana or Hashish) abuse
Tachycardia, labile blood pressure, headache, euphoria, dysphoria, depression, occasional anxiety and panic reactions, psychosis (rare). Poor memory and decreased motivation with chronic use.
38
Signs and symptoms of Cocaine and Amphetamines abuse
Tachycardia, labile blood pressure, hypertension, myocardial ischemia, arrhythmias, pulmonary edema, excitement, delirium, hallucinations to psychosis. Euphoria: feeling of excitation, well-being, and enhanced physical strength and mental capacity. Hyperreflexia, tremors, convulsions, mydriasis, sweating, hyperpyrexia, exhaustion, coma with overdose.
39
Signs and symptoms of Hallucinogens (LSD, PCP) abuse
Sympathomimetic and weak analgesic effects, altered perception and judgment; high doses may progress to toxic psychosis. PCP produces dissociative anesthesia with increasing doses.
40
Signs and symptoms of Opioids abuse
Respiratory depression, hypotension, bradycardia, constipation, euphoria (most marked with heroin). Pinpoint pupils with overdose; decreased level of consciousness to coma.
41
What are the hepatic risks associated with certain medications?
Impaired liver function, cholestatic jaundice, hepatic adenocarcinoma (liver cancer), and peliosis hepatis (blood-filled liver cysts).
42
What are the cardiovascular risks associated with certain medications?
Increased risk of myocardial infarction (MI), atherosclerosis, stroke, hypertension, dyslipidemia, and hypercoagulopathy.
43
What endocrine and psychiatric risks are associated with certain medications?
Testicular atrophy and gynecomastia in males, menstrual irregularities in females, aggressive behavior, mood swings, psychosis, and depression.
44
What anesthetic considerations should be taken for chronic steroid users?
Preoperative liver function tests (LFTs) should be obtained, monitor cardiovascular status closely, assess coagulation status, consider potential adrenal insufficiency, and stress-dose steroids may be required perioperatively.
45
What are the risks of herbal dietary supplements in the perioperative setting?
Certain herbs can affect blood clotting, glucose control, CNS function, and interact with anesthesia. Patients should bring their herbal products to preoperative assessment if unsure.
46
Which herbs increase bleeding risk?
Garlic, ginkgo, ginger, ginseng, vitamin E, feverfew.
47
Which herb reduces warfarin effect and increases clotting risk?
St. John’s Wort.
48
Which herbs can cause hypoglycemia?
Aloe vera, ginseng, fenugreek, cinnamon.
49
Which herbs increase sedation and potentiate anesthetic agents?
Kava and valerian root.
50
What is the risk associated with Ephedra (Ma Huang)?
Increases blood pressure, heart rate, arrhythmia risk, and may cause hypertensive crisis.
51
What should patients do regarding herbal supplements before surgery?
Patients should discontinue herbal supplements 2–3 weeks before surgery to avoid interactions.
52
What should be monitored if anticoagulant herbal use is suspected?
Monitor for excessive bleeding.
53
What should be assessed in diabetic patients using herbal glucose modulators?
Assess for hypoglycemia risk.
54
What caution should be taken with herbal supplements that enhance sedation?
Be cautious with herbal supplements such as kava and valerian.
55
Why is airway assessment important?
Every patient must undergo a preoperative airway evaluation to identify risks for difficult mask ventilation or endotracheal intubation.
56
What does the airway assessment include?
The assessment includes inspection of teeth, mouth, mandibular space, and neck to determine airway management challenges.
57
What is the Mallampati Classification?
Assesses tongue size relative to oral cavity.
58
How is the Mallampati Classification performed?
Patient sits upright, mouth wide open, tongue fully extended, and no phonation to prevent palate elevation.
59
What does Class I of the Mallampati Classification indicate?
Full visibility of soft palate, fauces, uvula, tonsillar pillars → Easy intubation.
60
What does Class II of the Mallampati Classification indicate?
Uvula partly visible → Moderate ease of intubation.
61
What does Class III of the Mallampati Classification indicate?
Only base of uvula visible → Potential difficulty.
62
What does Class IV of the Mallampati Classification indicate?
No uvula or soft palate visible → High risk of difficult intubation.
63
What is a limitation of the Mallampati classification?
It has a high false-positive and false-negative rate and should not be used alone.
64
What is the Thyromental Distance (TMD)?
Measures the distance from thyroid cartilage to mandibular border with neck fully extended, mouth closed.
65
What TMD measurement is associated with difficult intubation?
<6-7 cm (~3 fingerbreadths) is associated with difficult intubation due to misalignment of pharyngeal and laryngeal axes.
66
What does Interincisor Distance measure?
Measures mouth opening capability, which depends on temporomandibular joint (TMJ) mobility.
67
What is the normal Interincisor Distance?
≥4 cm (2-3 fingers width) = normal.
68
What Interincisor Distance indicates a risk for difficult intubation?
<2 fingers width = risk for difficult intubation.
69
What is the significance of TMJ mobility?
Some patients may have adequate mouth opening while awake but reduced TMJ mobility after anesthesia.
70
What is the 'sniffing position'?
Moderate flexion of the neck + full extension of the atlantooccipital joint optimizes alignment of the oral, pharyngeal, and laryngeal axes.
71
What conditions can limit neck extension?
Cervical arthritis, prior neck surgery, small C1 gap.
72
What does the Jaw Protrusion Test assess?
Patients should attempt to protrude the lower jaw forward and bite the upper lip.
73
What does inability to move the jaw forward indicate?
May indicate difficult laryngoscopy due to reduced maneuverability.
74
What are common risk factors for perioperative dental injury?
Preexisting poor dentition, limited neck motion, history of craniofacial abnormalities, prior head and neck surgery.
75
What should be documented in a preoperative dental assessment?
Inspect and document the condition of teeth before airway management to prevent false attribution of preexisting damage to anesthesia.
76
What poses a high risk of tooth injury during laryngoscopy?
Loose or protuberant maxillary incisors.
77
What should be noted regarding dental devices?
Crowns, braces, dentures, and prosthetic devices should be noted and removed unless necessary for mask fit.
78
What may need to be done for extremely loose teeth?
They may need extraction before laryngoscopy to prevent aspiration.
79
How is obesity classified?
Body weight >20% over ideal body weight = obesity.
80
What is morbid obesity?
Body weight >100% over ideal weight.
81
What are the BMI classifications?
Overweight: 25–29.9 kg/m²; Class 1 Obesity: 30–34.9 kg/m²; Class 2 Obesity: 35–39.9 kg/m²; Class 3 Obesity (Severe): ≥40 kg/m².
82
What percentage of U.S. adults are overweight or obese?
Two-thirds of U.S. adults are overweight or obese.
83
What are the health risks associated with obesity?
Increased risk for cardiovascular disease, sleep-disordered breathing, difficult airway management, metabolic disorders (diabetes, dyslipidemia), and increased perioperative complications.
84
What preoperative considerations should be made for obese patients?
Assess cardiovascular health per American Heart Association guidelines and screen for coronary disease if there is an abnormal ECG, history of coronary/valvular disease, or age >50 years with two or more risk factors.
85
What symptoms should be screened for obstructive sleep apnea (OSA)?
Snoring, apneic episodes, frequent arousals during sleep, morning headaches, and daytime somnolence.
86
What is the STOP-Bang Questionnaire used for?
It is used for OSA screening and has high sensitivity for identifying OSA risk.
87
What is the gold standard for diagnosing OSA?
Polysomnography (sleep study).
88
What airway management considerations are there for obese and OSA patients?
Obese patients with short, thick necks or OSA have a higher incidence of difficult intubation. Prepare for possible awake tracheal intubation if difficulty is anticipated.
89
What medications should be considered preoperatively for obese patients?
Antiobesity drugs (amphetamines, Schedule IV appetite suppressants) and antidepressants (fluoxetine, sertraline), which may interact with anesthesia.
90
What musculoskeletal disorders are common in anesthesia?
Osteoarthritis, ankylosing spondylitis (AS), and rheumatoid arthritis (RA).
91
What preoperative considerations should be made for AS and RA patients?
Chronic pain and inflammation can limit mobility and surgical positioning. Patients may require perioperative corticosteroid supplementation if on chronic steroid therapy.
92
Who is at risk for adrenal insufficiency?
Patients receiving >20 mg hydrocortisone daily for >3 weeks in the past year and those on chronic corticosteroid replacement therapy.
93
What systemic effects can AS and RA have on anesthesia?
Restrictive lung disease, pleural and pericardial effusions, cardiac conduction abnormalities, and increased risk of difficult venous access.
94
What should be assessed in a preoperative neurologic assessment?
Observe gait, ability to toe-and-heel walk, arm extension, grip strength, sensory perception, muscle reflexes, cranial nerve abnormalities, and mental status.
95
What indicates the need for intubation in neurologic assessment?
A Glasgow Coma Scale (GCS) score of <8 indicates coma and need for intubation.
96
What diagnostic tests are used for neurologic disorders?
Electromyography (EMG), electroencephalography (EEG), CT or MRI scans, and cerebral arteriography.
97
What are indicators of intracranial hypertension?
CT or MRI showing ≥0.5 cm midline shift of the brain, hydrocephalus, cerebral edema, or obliteration of CSF cisterns.
98
What considerations are there for carotid endarterectomy patients?
They require a full cardiac workup (ECG, stress test).
99
What anesthetic management should be considered for patients with intracranial hypertension?
Avoid CNS depressants in patients with ICP and altered consciousness.
100
What should be continued perioperatively for patients on anticonvulsant therapy?
Continue anticonvulsants (phenytoin, phenobarbital) and monitor CBC in long-term phenytoin users.
101
What should be monitored in corticosteroid therapy for CNS tumors?
Monitor blood glucose closely due to steroid-induced hyperglycemia.
102
What preexisting cardiac diseases should be assessed in preanesthesia cardiovascular risk assessment?
Hypertension, ischemic heart disease, valvular dysfunction, cardiac arrhythmias, cardiac conduction abnormalities, and ventricular failure.
103
What are comorbid conditions that increase cardiac risk?
Diabetes mellitus, Peripheral vascular disease, Chronic pulmonary disease, Obesity
104
How does the type of surgery influence cardiac risk?
The type of surgery influences perioperative cardiac risk; major cardiac events (MI, cardiac death) are more likely in high-risk procedures.
105
What is the Revised Cardiac Risk Index (RCRI)?
A tool used for predicting major postoperative cardiac complications.
106
What is a key predictor of perioperative cardiac complications?
Functional capacity, assessed using Metabolic Equivalent (MET) levels.
107
What MET level indicates good functional capacity?
Patients with good functional capacity can generally proceed with surgery if cardiac risk factors are managed (>4 METs).
108
What questions assess functional capacity?
1. Can you walk four blocks without stopping, regardless of symptoms? 2. Can you climb two flights of stairs without stopping, regardless of symptoms?
109
What is the New York Heart Association (NYHA) Classification?
A system used to categorize the severity of heart failure and functional impairment based on symptoms.
110
What are the updated classifications of hypertension?
Normal BP: <120/80 mmHg, Elevated BP: 120–129/<80 mmHg, Stage 1: 130–139/80–89 mmHg, Stage 2: ≥140/≥90 mmHg, Stage 3: ≥180/≥110 mmHg
111
What is the risk of uncontrolled hypertension during surgery?
Increases risk of myocardial ischemia and perioperative hemodynamic instability.
112
When should elective surgery be postponed?
If BP >180/110 mmHg, evidence of uncontrolled target-organ damage, or if postponement would significantly reduce perioperative risk.
113
What should be included in a preoperative hypertension evaluation?
History and medication review, evaluation for symptoms of cerebrovascular insufficiency and orthostatic hypotension.
114
What physical examination findings suggest Cushing’s disease?
Truncal obesity, purpura, striae.
115
What are anesthesia considerations for hypertensive patients?
Combination of antihypertensive drugs and anesthetics can cause excessive hypotension; monitor for cerebrovascular insufficiency.
116
What is Ischemic Heart Disease (IHD)?
Occurs due to an imbalance between myocardial oxygen demand and supply.
117
What are common risk factors for Ischemic Heart Disease?
Advanced age, Smoking, Diabetes mellitus, Hypertension, Pulmonary disease, History of myocardial infarction, Left ventricular dysfunction, Peripheral vascular disease.
118
What symptoms should be investigated in preoperative assessment for IHD?
Undue fatigue, Angina pectoris, Palpitations, Syncope, Dyspnea.
119
When is a 12-lead ECG recommended?
For known coronary artery disease, significant structural heart disease, or symptoms suggestive of ischemia or arrhythmia.
120
What characterizes stable angina?
Substernal discomfort with exertion, relieved by rest or nitroglycerin within 15 minutes.
121
What is unstable angina?
New-onset angina, progressively worsening angina, or angina occurring at rest.
122
What are the reinfarction rates post-myocardial infarction?
<30 days post-MI: 33%, 1–2 months: 19%, 3–6 months: 6%, >6 months: Lowest risk.
123
What are the ACC/AHA guidelines for surgery after MI?
Elective surgery should be delayed at least 60 days post-MI.
124
What are considerations for patients with coronary stents?
Bare Metal Stents have a 20% restenosis rate; Drug-Eluting Stents reduce this to 5% after 2 years.
125
What is the dual antiplatelet therapy (DAPT) for stent patients?
Aspirin (indefinitely) and a P2Y12 inhibitor for at least 6 months.
126
What should be assessed in patients with left ventricular dysfunction?
Active left ventricular failure is a significant risk factor; heart failure can be classified as HFpEF or HFrEF.
127
What are common signs of heart failure?
Pulmonary edema, paroxysmal nocturnal dyspnea, bilateral rales, S3 gallop.
128
What is the risk associated with severe aortic stenosis?
Linked to a 14 times higher perioperative sudden death risk.
129
What should be done for symptomatic aortic stenosis before surgery?
Requires cardiology consultation before elective surgery.
130
What are the classifications of cardiac arrhythmias?
Benign, Potentially malignant, Malignant.
131
What should be assessed in preoperative evaluation for arrhythmias?
Type, severity, and associated heart disease.
132
What are key considerations for cardiovascular implantable electronic devices?
Proper assessment minimizes risk; direct interrogation by a qualified team is required.
133
What are indications for temporary preoperative pacing?
Persistent bradycardia unresponsive to atropine, history of syncope with bifascicular block, exercise-induced dizziness.
134
What is the role of diagnostic testing in assessing cardiovascular disease?
Preoperative cardiac testing should only be done if results will influence patient management.
135
What findings indicate ischemia during exercise stress ECG?
ST-segment depression > 0.2 mV, early ST-segment depression, hypotensive response during the test.
136
What is Pharmacologic Stress Testing used for?
It is used for patients unable to perform exercise testing.
137
What do dipyridamole or adenosine do in stress testing?
They cause coronary blood flow redistribution without directly affecting heart contraction.
138
What does the Dobutamine stress test simulate?
It increases heart rate and contraction strength to simulate exercise conditions.
139
What are Advanced Imaging Techniques used for?
They help identify ischemic heart disease and cardiac risk.
140
Is routine testing with advanced imaging techniques recommended before all surgeries?
No, there is insufficient evidence to support routine testing before all surgeries.
141
What is Cardiac Catheterization used for?
It is used to define the severity of coronary artery disease (CAD).
142
Who is recommended for Cardiac Catheterization?
High-risk surgical patients or those with NYHA Class III or IV heart failure.
143
What significant arterial narrowing indicates severe CAD?
70% blockage in major coronary arteries or 50% blockage in the left main coronary artery.
144
What are key imaging findings that indicate poor ventricular function?
Cardiac index < 2.2 L/m², Left ventricular end-diastolic pressure > 18 mmHg, Ejection fraction (EF) < 40%, Akinesis or hypokinesis.
145
Who should receive cardioprotective pharmacotherapy before surgery?
High-risk patients with a history of angina, prior MI, heart failure, stroke, diabetes, or moderate-to-poor functional capacity.
146
What are the benefits of Statins in high-risk patients?
They improve endothelial function, reduce oxidative stress and inflammation, and increase plaque stability.
147
When should statin therapy be started before surgery?
At least 30 days before surgery for maximal effect.
148
What do β-Blockers do in high-risk surgical patients?
They reduce oxygen demand mismatch, lower myocardial oxygen consumption, and stabilize heart rate.
149
Who should receive β-Blockers?
Patients already on β-blockers for ischemic heart disease, arrhythmias, or hypertension, and high-risk cardiovascular patients.
150
What should be avoided when starting β-Blockers?
Do not start perioperatively in low-risk patients due to potential increased risk of mortality and complications.
151
What are ACE Inhibitors used for?
To reduce heart failure symptoms and improve long-term outcomes.
152
In which patients are ACE Inhibitors beneficial?
Patients with heart failure with reduced ejection fraction, history of MI, or moderate-to-severe cardiovascular disease.
153
What is Dual Antiplatelet Therapy (DAPT)?
It includes Aspirin and P2Y12 inhibitors to prevent stent thrombosis after PCI.
154
When should elective non-cardiac surgery be delayed after stent placement?
30 days after Bare Metal Stent placement and 6 months after Drug-Eluting Stent placement.
155
What are Novel Oral Anticoagulants (NOACs) used for?
They are used for Atrial fibrillation, deep venous thrombosis, pulmonary embolism, and sometimes prosthetic heart valves.
156
What are the types of NOACs?
Factor Xa Inhibitors (Rivaroxaban, Apixaban) and Thrombin Inhibitors (Dabigatran).
157
What is the CHADS₂ scoring system used for?
To assess the risk of atrial fibrillation patients for perioperative anticoagulant management.
158
What are the risk factors for increased postoperative pulmonary complications?
Preoperative sepsis, emergency surgeries, age >50, smoking, cardiovascular disease, diabetes, kidney disease, obesity, and prolonged anesthesia.
159
What should be done if a COPD patient has severe dyspnea before elective surgery?
Elective surgery should be postponed.
160
What is indicated for thick, purulent sputum with pulmonary infiltrates?
Antibiotics are indicated.
161
What is the role of incentive spirometry in preoperative management?
It reduces post-op pulmonary complications after upper abdominal surgery.
162
What are the symptoms of a URI in children?
Sore throat, nasal congestion, rhinorrhea, malaise, fever, wheezing, and stridor.
163
What should be done if a child has a productive cough and lower respiratory tract involvement before surgery?
Delay surgery for at least 2 weeks.
164
What symptoms should be looked for in the gastrointestinal system during preoperative evaluation?
Nausea, vomiting, diarrhea, bleeding, pain, distension, dysphagia, reflux.
165
What should be checked for fluid and electrolyte imbalances?
Associated with weight loss or malabsorption.
166
What should be checked in cases of active gastrointestinal bleeding?
Hemoglobin & hematocrit (may appear falsely elevated due to hemoconcentration).
167
What imaging techniques are used to check for obstruction or masses in the gastrointestinal system?
CT scan/X-ray.
168
What considerations should be made for patients with GERD or Peptic Ulcer Disease?
Use prophylactic measures to reduce aspiration risk.
169
What are the types of liver disease to consider in preoperative evaluation?
Acute & chronic liver disease (e.g., hepatitis, cirrhosis) and cholestatic liver disease (e.g., biliary obstruction).
170
What is a limitation of laboratory tests in detecting liver disease?
Laboratory tests often fail to detect early liver disease.
171
What symptoms indicate mild hepatic dysfunction?
Malaise, weight loss, mild jaundice.
172
What laboratory findings may indicate early cirrhosis or hepatitis?
Mildly elevated bilirubin & transaminases.
173
What are the indicators of severe hepatic dysfunction?
Coagulopathy, extreme jaundice, ascites, encephalopathy, hepatorenal failure.
174
What should be done for patients with severe hepatic dysfunction?
Emergency or palliative procedures only; elective surgery postponed.
175
What is the risk associated with liver failure patients?
High morbidity & mortality risk.
176
What is recommended for preoperative optimization for patients with liver disease?
Consultation with gastroenterologist for high-risk patients.
177
What should be done to correct coagulopathy in liver disease patients?
Vitamin K (phytonadione), fresh frozen plasma (FFP), cryoprecipitate.
178
What should be monitored due to the risk of hypoglycemia in liver disease patients?
Blood glucose.
179
What should be avoided in patients with hepatic encephalopathy?
Sedatives.
180
What laboratory tests are key for liver function?
Liver Function Tests (LFTs) have limitations.
181
What does alkaline phosphatase elevation suggest?
Cholestasis (bile duct obstruction).
182
What does prolonged prothrombin time (PT) indicate?
Most reliable indicator of acute liver dysfunction.
183
What is the Child-Pugh Score used for?
Predicts surgical mortality in cirrhosis.
184
What are the risk classes in the Child-Pugh Score?
Class A: 10% surgical mortality (low risk), Class B: 30% surgical mortality (moderate risk), Class C: 80% surgical mortality (surgery should be delayed if possible).
185
What are the preoperative considerations for the renal system?
Acute kidney injury (AKI), chronic kidney disease (CKD) or renal failure, polyuria, urinary retention, hematuria, recurrent infections.
186
What signs indicate dehydration in renal evaluation?
Dry mucosa, postural hypotension, tachycardia.
187
What can polyuria indicate?
Diabetes insipidus or uncontrolled diabetes.
188
What should be ruled out in cases of recurrent infections?
Cystitis, pyelonephritis, or glomerulonephritis.
189
What are the diagnostic criteria for Acute Kidney Injury (AKI)?
Serum creatinine >26.4 µmol/L within 48 hours, serum creatinine >1.5 times baseline in 7 days, urine output <0.5 mL/kg for 6 hours.
190
What is more accurate than Blood Urea Nitrogen (BUN) for kidney function?
Serum creatinine.
191
What is the GFR calculation formula?
GFR = (U x V)/ P
## Footnote
U = Urinary creatinine concentration, V = Urine volume (mL/min), P = Plasma creatinine concentration.
192
What should be done preoperatively for renal disease patients?
Preoperative urinalysis & culture, monitor electrolyte imbalances, avoid nephrotoxic medications, optimize hydration & correct metabolic abnormalities.
193
What are key concerns in dialysis patients?
Ongoing hemodialysis or peritoneal dialysis, maintain homeostasis despite abnormal BUN & creatinine levels.
194
What should potassium levels be checked for before surgery?
6-8 hours before surgery; if K+ >5.5 mEq/L, delay elective surgery.
195
What may be necessary if severe anemia is present in chronic renal failure patients?
Blood transfusion may be necessary before surgery.
196
What is a risk associated with frequent blood transfusions?
Risk of infections (Hepatitis, HIV).
197
What should be monitored in perioperative management for renal failure patients?
Vascular access sites (AV fistulas) for infection & patency.
198
What should be avoided in dialysis-access limbs?
IV lines and blood pressure measurements.
199
What are the endocrine system preoperative considerations?
Diabetes Mellitus, Thyroid Dysfunction, Adrenal Insufficiency.
200
What is the perioperative risk associated with Diabetes Mellitus?
Increases perioperative risk; diabetic patients have a 5-10x higher morbidity & mortality risk in surgery.
201
What are the types of diabetes?
Type 1 (Insulin-dependent) and Type 2 (Non-insulin dependent).
202
What should be assessed in the preoperative evaluation of diabetes patients?
Metabolic control, cardiovascular, renal, and neurological complications.
203
What does Hemoglobin A1c (HbA1c) measure?
Long-term glycemic control.
204
What are the HbA1c levels indicating risk?
Normal: <5.7%, High Risk: 5.7-6.4%, Diabetic: ≥6.5%.
205
What is the goal of perioperative glucose management?
Maintain glucose <180 mg/dL while avoiding hypoglycemia.
206
What should be done the night before surgery for diabetic patients?
Continue usual evening dose of insulin; if tightly controlled, may reduce dose by ⅓ to ½.
207
What should be done on the morning of surgery for fasting patients needing insulin?
Withhold oral hypoglycemics, short-acting insulins withheld unless glucose >200 mg/dL.
208
What should be done for insulin pumps before surgery?
Determine type of insulin, basal rate, sensitivity factor; ensure pump is working properly.
209
What is hyperthyroidism?
Excess secretion of thyroid hormones (T3 & T4).
210
What are common causes of hyperthyroidism?
Graves' disease, toxic multinodular goiter, thyroid carcinoma, pituitary tumors secreting TSH.
211
What is the goal of preoperative management for hyperthyroid patients?
Achieve a euthyroid state before elective surgery.
212
What medications are used in the preoperative management of hyperthyroidism?
Antithyroid drugs (Methimazole or Propylthiouracil), iodine therapy, beta-blockers.
213
What should be done if a euthyroid state cannot be achieved before surgery?
Continuous esmolol infusion to control HR, higher doses of sedatives, avoid anticholinergics.
214
What is hypothyroidism?
Deficiency of thyroid hormones (T3 & T4).
215
What are common causes of hypothyroidism?
Hashimoto’s thyroiditis, iodine deficiency, post-surgical thyroid removal.
216
What is the goal of preoperative management for hypothyroid patients?
Restore normal thyroid hormone levels.
217
What is myxedema coma?
Life-threatening emergency with bradycardia, hypothermia, altered mental status, hypotension.
218
What are the clinical features of hyperadrenocorticism (Cushing Syndrome)?
Hypertension, truncal obesity, moon facies, abdominal striae, easy bruising.
219
What are the perioperative considerations for patients with hyperadrenocorticism?
Monitor blood pressure & glucose levels, caution with immune suppression.
220
What are the clinical features of hyperaldosteronism?
Hypertension, marked hypokalemia, metabolic alkalosis.
221
What should be monitored and corrected in hyperaldosteronism?
Potassium levels and manage hypertension.
222
What are the clinical features of adrenal insufficiency (Addison’s Disease)?
Hypotension, weight loss.
223
What is the effect of excess mineralocorticoids?
Excess aldosterone production leading to sodium and water retention.
## Footnote
Clinical features include hypertension, marked hypokalemia (low potassium levels <3 mmol/L), and metabolic alkalosis.
224
What are the perioperative considerations for excess mineralocorticoids?
Monitor & correct potassium levels, manage hypertension, and evaluate volume status before surgery.
225
What is adrenal insufficiency (Addison’s Disease)?
Primary adrenal failure (Addison’s) or secondary suppression from long-term steroid therapy.
## Footnote
Clinical features include hypotension, weight loss, fatigue, muscle wasting, skin hyperpigmentation (Addison’s), hyponatremia, hyperkalemia, and hypoglycemia.
226
What are the perioperative considerations for adrenal insufficiency?
Patients on chronic steroids require stress-dose steroids to prevent adrenal crisis, assess electrolyte imbalances and correct before surgery, and hypotension unresponsive to fluids may indicate adrenal insufficiency requiring hydrocortisone supplementation.
227
What is the purpose of The Joint Commission Universal Protocol?
To prevent wrong-site, wrong-procedure, and wrong-patient surgeries.
228
What are the key steps in the preoperative verification process?
1. Preoperative verification process
2. Marking the surgical site
3. 'Time-Out' before incision
229
What is the goal of preoperative fasting guidelines?
To balance aspiration risk with minimizing patient discomfort.
230
What are the fasting guidelines for clear liquids before surgery?
Allowed up to 2 hours before surgery.
231
What are the fasting guidelines for a light meal before surgery?
Up to 6 hours before surgery.
232
What are the fasting guidelines for a heavy meal before surgery?
8 hours fasting required.
233
What factors increase the risk of pulmonary aspiration?
GERD, gastroparesis, obesity, diabetes, emergency surgery, and pregnancy.
234
What are some preventive strategies for pulmonary aspiration?
1. Prokinetics (Metoclopramide)
2. Acid suppression (Famotidine, Omeprazole)
3. Antiemetics (Ondansetron)
235
What is the ASA Physical Status Classification used for?
To assess preoperative patient health.
236
What does ASA I represent?
Healthy patient, no medical conditions.
237
What does ASA II represent?
Mild systemic disease (e.g., controlled hypertension).
238
What does ASA III represent?
Severe systemic disease, functionally limiting (e.g., poorly controlled diabetes).
239
What does ASA IV represent?
Severe disease that is a constant threat to life (e.g., unstable angina).
240
What does ASA V represent?
Moribund patient, unlikely to survive without surgery.
241
What does ASA VI represent?
Brain-dead organ donor.
242
What does the 'E' denote in the ASA classification?
'E' denotes emergency cases.
243
What is transection in the context of peripheral nerve injury?
Complete severance of the nerve fiber or fascicle, typically due to surgical scalpel or traumatic incision/excision.
## Footnote
Results in loss of both sensory and motor function distal to injury and Wallerian degeneration of the distal axon. Recovery potential is limited, depending on the extent of damage and whether nerve ends are surgically reapproximated.
244
What occurs during compression of a peripheral nerve?
The nerve is trapped between a rigid surface (e.g., bone) and external force (e.g., body weight).
## Footnote
Examples include common peroneal nerve compression in lateral decubitus position and ulnar nerve compression at the elbow when arm is extended without padding.
245
What are the pathophysiologic consequences of nerve compression?
Mechanical deformation of nerve sheath, ischemia due to compression of vasa nervorum, and impaired axonal transport.
246
What happens during stretch (traction) injury to nerves?
Excessive elongation causes axoplasmic flow disruption, microvascular injury, and axon rupture or demyelination.
## Footnote
Stretch > 20% of nerve’s resting length is often damaging.
247
What are some susceptible sites for stretch injuries?
Brachial plexus (stretched by arm abduction > 90°), sciatic nerve (vulnerable in extreme hip flexion or knee extension), and femoral nerve (may be kinked beneath inguinal ligament in exaggerated lithotomy position).
248
What is traction over fixed structures?
A subtype of stretch injury where a nerve is tethered over a ligament or bone, increasing localized stress.
## Footnote
Example includes femoral nerve traction as it crosses under the inguinal ligament when hips are flexed toward the abdomen.
249
What is central to nerve injury pathophysiology?
Ischemia is central to nerve injury pathophysiology.
250
What disrupts perfusion to epineurial vessels, perineurial capillaries, and endoneurial microcirculation?
Stretch, compression, or tissue trauma disrupts perfusion.
251
What is the effect of external pressure on venous return?
External pressure reduces venous return, causing increased capillary hydrostatic pressure and edema formation in interstitial and endoneurial spaces.
252
What does edema do to arterioles?
Edema further compresses arterioles, leading to reduced arterial inflow.
253
What is the first step in the cycle of ischemic injury?
Reduced capillary blood flow leads to decreased oxygen and nutrients.
254
What happens to ATP production during ischemic injury?
ATP production decreases.
255
What fails due to reduced ATP production?
Na⁺/K⁺ ATPase fails.
256
What accumulates intracellularly due to ischemia?
Intracellular Na⁺ accumulates.
257
What is the result of intracellular Na⁺ accumulation?
Osmotic water influx occurs, leading to cellular swelling (cytotoxic edema) and increased interstitial pressure.
258
What does increased interstitial pressure lead to?
Further collapse of capillary perfusion.
259
What propagates due to the cycle of ischemic injury?
Ischemia propagates, leading to axonal injury and degeneration.
260
How does low systemic MAP affect ischemia?
If systemic MAP drops, the arterial-venous gradient is reduced, worsening ischemic perfusion.
261
What is the function of the Axon?
Conducts electrical impulses
262
What is the role of the Neurolemma (Schwann cell)?
Myelination and regeneration
263
What does the Endoneurium do?
Surrounds individual axons with loose connective tissue
264
What is the function of the Perineurium?
Tough sheath that bundles axons into fascicles
265
What does the Inner Epineurium support?
Supports fascicle structure and vascular supply
266
What is the function of the Outer Epineurium?
Outer covering of the nerve; allows movement across joints
267
What is the purpose of the Nerve Trunk Covering?
Loose connective tissue that aids in gliding during joint motion
268
What are Epineurial vessels?
Parallel to nerve trunk; form collateral loops
269
How do Perineurial and endoneurial capillaries run?
Run obliquely → more vulnerable to compression from edema
270
What is a characteristic of the Endoneurial space?
Lacks lymphatic drainage → edema and fluid buildup cannot be cleared easily
271
What can edema in the Endoneurial space restrict?
Can severely restrict capillary flow
272
What is a risk factor associated with inadequate padding?
Compression over bony prominences (e.g., elbows, knees, fibular head)
273
What is the effect of prolonged surgical time?
Sustained ischemia or compression risk
274
What can extremes of positioning cause?
Nerve stretch or traction
275
What is the effect of hypotension during anesthesia?
Reduced perfusion to already stressed nerves
276
How does obesity or edema affect nerves?
Amplifies pressure, restricts movement of nerve and its blood supply
277
What does neuropathy (e.g., diabetic) increase?
Increased baseline vulnerability
278
What is a positioning principle to prevent nerve injury?
Avoid excessive joint angles (e.g., shoulder abduction > 90°)
279
What type of padding should be used?
Use soft padding over bony prominences
280
What should be monitored to minimize surgical time?
Monitor and minimize surgical time in high-risk positions
281
What is the recommended MAP maintenance?
Ensure MAP > 65 mmHg to preserve perfusion
282
What should be documented pre- and post-op?
Pre- and post-op neuro exams for early detection and legal documentation
283
What is the multifactorial etiology of Peripheral Nerve Injuries (PPNIs)?
PPNIs arise from a complex interplay of mechanical forces, patient factors, and procedural variables.
284
What are the mechanical forces contributing to PPNIs?
Compression, stretch, traction, or transection.
285
What patient factors contribute to PPNIs?
Comorbidities, age, gender, BMI.
286
What procedural variables can lead to PPNIs?
Duration, anesthetic technique, positioning equipment.
287
What are common contributing factors to PPNIs?
Improper use of positioning devices, prolonged surgery, and certain anesthetic choices.
288
What is a risk of prolonged surgery in relation to PPNIs?
Time-dependent tissue compression and perfusion impairment.
289
How can anesthetic choices contribute to PPNIs?
General anesthesia, hypotensive techniques, and neuromuscular blockade can blunt patient responses and mask nerve injury.
290
What physiologic risk enhancers can worsen nerve ischemia?
Systemic hypotension, hypoxia, hypothermia, and electrolyte disturbances.
291
What are the risks of improper positioning devices?
Overtight straps or improperly placed padding can cause skin breakdown or compress nerves.
292
What is an example of nerve compression due to improper positioning?
Lateral femoral cutaneous nerve compressed by tight tape across the groin leads to meralgia paresthetica.
## Footnote
Example of nerve compression due to improper positioning.
293
What are the risks associated with arm positioning?
Shoulder braces in Trendelenburg or prone can compress the brachial plexus, and arm abduction > 90° can stretch it.
294
What is the most frequent nerve injury post-op?
Ulnar Neuropathy.
295
What mechanisms can lead to Ulnar Neuropathy?
Elbow flexion >90°, direct pressure on the medial elbow, prolonged immobility, and improper pronation on armboards.
296
What are the risk factors for Ulnar Neuropathy?
Male gender, thin body habitus, prolonged bedrest, subclinical neuropathy.
297
What is the most commonly injured upper extremity nerve group?
Brachial Plexus.
298
What are the risk factors for Brachial Plexus Injury?
Arm abduction >90°, head rotation away from the abducted arm, shoulder braces in Trendelenburg or prone, and improperly placed sternal retractors.
299
Where do Brachial Plexus Injuries most often occur?
At the clavicle–first rib junction or under the pectoralis minor.
300
What is the consequence of misplacing the axillary roll?
Placing the roll too high compresses the brachial plexus or axillary vessels.
301
What is the rare but devastating injury associated with neuraxial blockade?
Spinal Cord Injury.
302
What can cause spinal cord injury during surgery?
Neuraxial blockade in anticoagulated patients and hyperflexion of the neck.
303
What is the pathophysiology of spinal cord ischemia?
Cord moves anteriorly when neck is flexed, leading to compression against the vertebral body and reduced spinal cord perfusion.
304
What are some preventive measures for spinal cord injury?
Maintain ≥2 fingerbreadths between sternum and mandible, avoid excessive Trendelenburg, and monitor MAP.
305
What is Postoperative Visual Loss (POVL)?
A rare, non-ophthalmic complication of spine, cardiac, and head/neck surgeries.
306
What are the five major causes of POVL?
Ischemic Optic Neuropathy (ION), Central Retinal Artery Occlusion (CRAO), Central Retinal Vein Occlusion, Cortical blindness, Glycine toxicity.
307
What are the types of Ischemic Optic Neuropathy (ION)?
AION (anterior) and PION (posterior optic nerve ischemia).
308
What factors impair autoregulation in ION?
Hypotension, anemia, vascular disease, diabetes.
309
What are the risk factors for Ischemic Optic Neuropathy?
Male sex, obesity, longer surgery duration, blood loss & anemia, prone positioning, intraoperative hypotension.
310
What typically causes Central Retinal Artery Occlusion (CRAO)?
Direct external eye pressure, often from headrests.
311
What are the associated risks for CRAO?
Prone surgeries, cardiac surgery with head-down position, and horseshoe headrests.
312
What can cause Central Retinal Vein Occlusion?
Globe compression or venous outflow obstruction.
313
What increases the risk of Central Retinal Vein Occlusion?
Trendelenburg position, elevated intraabdominal pressure, and improper head positioning.
314
What are key preventive measures for POVL?
Safe hematocrit should be maintained, and deliberate hypotension should be avoided in hypertensive patients and those with vascular risk factors.
315
What is the preferred patient positioning to prevent POVL?
Avoid direct pressure on eyes using foam headrests with cutouts and maintain head in neutral alignment, ideally level or slightly elevated (10° head-up tilt) relative to heart.
316
What should be monitored during prone positioning?
Monitor face, eyes, and neck frequently, use a head support that allows visual inspection, and ensure no compression of globe or orbit.
317
What should patients be informed about during preoperative consent?
Patients undergoing prone, prolonged, or steep Trendelenburg surgeries with comorbidities (HTN, DM, obesity) must be informed of POVL risk.
318
What is compartment syndrome?
A surgical emergency where increased pressure within a closed fascial compartment leads to decreased tissue perfusion, resulting in nerve ischemia, muscle infarction, and potentially limb loss.
319
What are the hemodynamic considerations related to compartment syndrome?
Arterial pressure to elevated limbs decreases by ~0.75 mmHg per cm above the right atrium, which can create a low-flow ischemic state.
320
What are high-risk positions for developing compartment syndrome?
Lithotomy position (beyond 2–3 hours), Trendelenburg position, combined lithotomy and Trendelenburg, tightly wrapped limbs, or improper shoulder supports.
321
What are some risk factors for compartment syndrome?
Long surgical duration, prolonged limb elevation, obesity, advanced age, hypotension, and use of vasoconstrictors.
322
What are early signs of compartment syndrome?
Deep, intense pain out of proportion to the surgical site and pain exacerbated by passive stretching of the involved muscle group.
323
What are late signs of compartment syndrome indicating irreversible damage?
Pulselessness, paralysis, dark urine (myoglobinuria), and renal failure.
324
How is compartment syndrome diagnosed?
Diagnosis is primarily clinical, but compartment pressure measurement may be used if uncertain, with specific pressure thresholds.
325
What is the definitive treatment for compartment syndrome?
Emergent fasciotomy to release all involved muscle compartments; delay > 6 hours increases risk of permanent disability.
326
What are prevention strategies for anesthesia providers?
Monitor surgical duration, periodically return legs to horizontal position, maintain adequate MAP, and ensure appropriate padding under limbs.
327
What are CRNA/SRNA implications in preventing compartment syndrome?
Perform preoperative risk assessment, ensure precise positioning, maintain intraoperative vigilance, and educate the team on time limits in lithotomy.
328
What is the summary of key points regarding compartment syndrome?
Compartment syndrome is rare but devastating and almost always preventable; delays in diagnosis can result in permanent damage or death.
329
What are the general effects of anesthesia on the cardiovascular system?
Vasodilation and myocardial depression lead to:
- ↓ preload, ↓ SVR, ↓ MAP
- ↓ baroreceptor response and impaired compensatory mechanisms.
Opioids & beta blockers can blunt the sympathetic response and further depress cardiac output.
330
How does MAP change with body position?
MAP changes ~2 mm Hg per inch height difference between the heart and the body region.
Higher elevation → lower perfusion, important in sitting, lithotomy, and head-up positions.
331
What are the cardiovascular changes in the supine position?
Baseline for comparison.
CVP, CI, and PCWP typically stable.
332
What happens to preload in the sitting, lateral, and flexed lateral positions?
Blood pools in legs → ↓ preload.
Hemodynamic changes depend on elevation:
- 45° elevation: minor CV effects
- 90° elevation: ↓ preload, ↓ CO, possible hypotension.
Used cautiously in neurosurgical cases (risk of venous air embolism).
333
What are the effects of the prone position on the cardiovascular system?
↑ CVP due to abdominal compression.
↓ LV compliance → ↓ CO.
Position-dependent effect: variable depending on chest/abdominal support.
Pulmonary vascular resistance may increase due to:
- Compression of thoracic structures
- ↓ venous return from extremities.
334
What is the autotransfusion effect in the lithotomy position?
Autotransfusion effect from leg elevation:
↑ preload, ↑ CO temporarily.
In patients with limited cardiac reserve:
- Risk of overload, ↑ myocardial work
- May trigger ischemia, especially when combined with Trendelenburg.
335
What are the physiological effects of the Trendelenburg position?
Head-down tilt → ↑ central blood volume.
Physiologic effects:
- ↑ CVP, ↑ PAP, ↑ PCWP
- Conflicting evidence on CI and MAP.
In normovolemic patients: ↑ stroke volume and MAP.
In hypovolemic or cardiac patients:
- ↓ CI, worsened cardiac output, ↑ myocardial oxygen demand.
Can mask hypovolemia, which only becomes apparent when returned to supine.
⚠️ May increase myocardial workload in CAD patients due to ↑ preload.
336
What are the risks associated with combined lithotomy and Trendelenburg positions?
Compounded increase in central volume, increased risk of myocardial ischemia, elevated PCWP, PAP, CVP, decreased cardiac output, and worsened performance on the Frank-Starling curve in heart failure.
337
What is the effect of elevated legs above the heart in patients with Peripheral Vascular Disease?
Decreased perfusion pressure to distal limbs, leading to a risk of ischemia and compartment syndrome.
338
What are the effects of Trendelenburg and prone positions on intracranial and ophthalmic concerns?
Increased venous pressures in the head, leading to facial, orbital, and pharyngeal edema, increased ICP due to jugular congestion, and decreased cerebral perfusion pressure (CPP).
339
What are the associated complications of increased venous pressures in the head?
Post-op vision loss (POVL), airway edema, and macroglossia.
340
What is a preventative strategy for managing positional complications in vulnerable patients?
Keep the head level or above the heart in the prone position.
341
What strategies can minimize positional hemodynamic changes?
1. Use lower MAC (< 0.5) to reduce anesthetic-induced vasodilation. 2. Consider invasive monitoring for significant elevation changes. 3. Judicious fluid administration: correct volume before position change and avoid excess fluid in cardiac-compromised patients. 4. Gradual position changes to avoid abrupt preload/afterload shifts. 5. Terminate volatile agents and return patient to supine if unstable.
342
What muscles are involved in normal respiration during spontaneous breathing?
The diaphragm and intercostal muscles expand the thoracic cavity in the anterior-posterior and lateral dimensions.
343
What creates negative intrathoracic pressure during normal respiration?
The downward movement of the diaphragm.
344
What factors affect effective lung expansion?
Lung elastance and compliance, chest wall compliance, shape and volume of the thoracic cavity, and freedom of abdominal content movement.
345
What are the effects of general anesthesia on respiratory mechanics?
It causes muscle relaxation, loss of diaphragmatic tone, and positive pressure ventilation, blunting compensatory reflexes, leading to decreased compliance and ventilation.
346
How can positioning affect respiratory mechanics in surgical patients?
Positioning can alter diaphragmatic excursion, change lung volume and regional compliance, affect distribution of ventilation and perfusion, and exacerbate mismatch between ventilation (V) and perfusion (Q).
347
What are the effects of the supine position on lung volumes?
The diaphragm is pushed cephalad by abdominal viscera, leading to decreased lung volumes, decreased Functional Residual Capacity (FRC), and Total Lung Capacity (TLC).
348
What is a risk associated with the supine position?
Increased risk of atelectasis due to dependent lung collapse.
349
What are the benefits of the prone position for oxygenation?
It improves oxygenation and V/Q matching by alleviating anterior mediastinal compression on posterior lungs and better expansion of dorsal lung segments.
350
What risks are associated with the prone position?
Diaphragmatic motion may be restricted if the abdomen is compressed, and best results are achieved when the abdomen hangs freely.
351
What happens to lung recruitment in the prone position?
It may increase FRC in some patients due to lung recruitment and improved chest wall dynamics.
352
How does lateral decubitus position affect ventilation and perfusion?
In awake, spontaneous ventilation, both favor the dependent lung, but in anesthetized, paralyzed patients, ventilation shifts to the nondependent lung, causing V/Q mismatch.
353
What is a clinical consequence of lateral decubitus position?
Hypoxic pulmonary vasoconstriction helps redistribute blood flow away from poorly ventilated regions.
354
What is the effect of the lithotomy position on respiratory mechanics?
Little effect in healthy, conscious individuals, but exaggerated lithotomy can limit diaphragmatic excursion and reduce lung compliance.
355
What are the downsides of the sitting position for ventilation?
If the legs are elevated or flexed at the hips, it can cause abdominal compression, reducing FRC.
356
What is the Trendelenburg position's effect on respiratory mechanics?
It severely restricts diaphragmatic movement, decreases FRC, and increases closing volumes.
357
What complications can arise from prolonged Trendelenburg position?
Increased airway edema, facial swelling, and visual complications (POVL) are concerns.
358
What effect does gravity have on perfusion?
Gravity creates a perfusion gradient: more blood to dependent regions.
359
Where is ventilation generally better?
Ventilation is generally better in nondependent regions.
360
What disrupts the normal V/Q pattern in anesthesia?
Compliance changes, diaphragmatic inhibition, paralysis, and mechanical ventilation alter gas exchange.
361
What is a concentric perfusion pattern?
Central lung areas may receive more flow regardless of gravity.
362
What factors influence regional perfusion?
Cardiac output, pulmonary artery pressures, pleural pressure, and vessel branching architecture.
363
What affects diaphragm movement?
Movement is affected by obesity, abdominal surgery, pneumoperitoneum, and positional compression (especially Trendelenburg & prone).
364
How can positioning devices affect diaphragm excursion?
They can impair excursion if placed incorrectly; proper support is crucial to avoid hypoventilation or compartment pressures.
365
What is the Supine Position (Dorsal Decubitus) used for?
Most commonly used position for procedures involving head, neck, chest, abdomen, and extremities.
366
What are the positioning guidelines for the Supine Position?
Head in neutral position on donut or pillow; arms tucked at sides with palms facing hips or placed on padded armboards; arms abducted < 90°; knees slightly flexed; heels elevated off mattress.
367
What are the complications of the Supine Position?
Ulnar nerve injury, brachial plexus injury, back pain, alopecia, pressure sores.
368
What is the Trendelenburg Position used for?
Temporarily used to improve venous return during hypotension; common in gynecologic, urologic, and robotic-assisted surgeries.
369
What are the physiologic effects of the Trendelenburg Position?
Increased intracranial, intraocular, and central venous pressures; facial, tongue, and airway edema; decreased lung compliance.
370
What are the complications of the Trendelenburg Position?
Brachial plexus injury, sliding on OR table, airway edema, increased risk of POVL.
371
What is the Reverse Trendelenburg Position used for?
Used for laparoscopic upper abdominal surgeries and head/neck surgeries.
372
What are the physiologic effects of the Reverse Trendelenburg Position?
Decreased venous return and MAP to the brain; may cause hypotension.
373
What are the complications of the Reverse Trendelenburg Position?
Risk of cerebral hypoperfusion; pressure ulcers or neuropathies from table straps; footboard preferred to prevent sliding.
374
What is the Lithotomy Position used for?
Procedures involving the perineum, rectum, bladder, and gynecologic organs.
375
What are the positioning techniques for the Lithotomy Position?
Legs elevated simultaneously in stirrups; arms tucked or on armboards; avoid extreme hip flexion or abduction.
376
What are the complications of the Lithotomy Position?
Peroneal nerve injury, saphenous nerve injury, femoral or obturator nerve injury, hip dislocation, crush injury risk.
377
What is the Lateral Decubitus Position used for?
Thoracic, renal, and orthopedic surgeries.
378
What are the positioning techniques for the Lateral Decubitus Position?
Spine, head, and hips aligned; dependent leg flexed; arms positioned appropriately; axillary roll placed.
379
What are the complications of the Lateral Decubitus Position?
Brachial plexus injury, dependent eye/ear pressure injuries, inaccurate BP readings, rhabdomyolysis, peroneal nerve compression.
380
What is the Sitting Position used for?
Posterior fossa, cervical spine, shoulder surgeries.
381
What are the positioning guidelines for the Sitting Position?
Head stabilized with fixation; neck flexion allows ≥ 2 fingerbreadths; arms supported and secured.
382
What are the complications of the Sitting Position?
Venous Air Embolism, Paradoxical Air Embolism, Bezold–Jarisch reflex, jugular venous obstruction, cervical spine injury, accidental extubation.
383
What is the Prone Position used for?
Spine surgery, posterior cranial procedures, rectal surgeries.
384
What are the positioning techniques for the Prone Position?
Patient logrolled prone; torso supported; abdomen must hang freely; arms tucked or on armboards; face positioned neutrally.
385
What are the complications of the Prone Position?
POVL, corneal abrasions, brachial plexus stretch, abdominal compression, airway complications, rhabdomyolysis.
386
What positions increase the risk of facial and airway edema?
Prone, Trendelenburg (head-down), Sitting with neck hyperflexed
387
What are the pathophysiological factors contributing to edema?
Gravitational forces and hydrostatic pressure impair venous return from the face, tongue, and oropharynx. Jugular venous compression worsens with neck flexion in the sitting position. Impaired lymphatic drainage further exacerbates swelling.
388
What devices can contribute to airway edema?
Oral airways, Endotracheal tubes, Esophageal stethoscopes
389
What structures can be compressed by airway devices?
Base of the tongue, Epiglottis, Arytenoids
390
What is macroglossia?
Tongue swelling due to venous congestion, lymphatic obstruction, or mechanical compression.
391
In what positions is macroglossia commonly seen?
Prone and Trendelenburg, Sitting position with head flexion
392
What is supraglottic edema?
Swelling of the arytenoids, epiglottis, and pharyngeal tissues.
393
What can cause supraglottic edema?
Tube compression, prolonged pressure on upper airway structures, head/neck malposition.
394
What are intraoperative airway management strategies?
Secure the ET tube well before position changes. Re-confirm breath sounds and capnography after any repositioning. Monitor for increased airway pressures or desaturation.
395
What should be considered for postoperative extubation if macroglossia or airway edema is suspected?
Delay extubation until swelling resolves. Consider direct laryngoscopy to inspect airway before extubation. Check for air leak around deflated ET tube cuff (a sign airway swelling has resolved).
396
What are some preventive tips for airway edema?
Avoid excessive neck flexion, especially in the sitting position. Use proper padding for the head and face during prone and Trendelenburg cases. Minimize intraoral instrumentation time when possible.
397
What should be done to minimize airway trauma during intubation?
Suction airway secretions and minimize airway trauma during intubation and manipulation.
