Pediatric Anesthesia Lecture 1-2 Flashcards
(106 cards)
1
Q
Resistance is inversely related to airway radius to the ____ power.
A
Poiseuille’s Law
4th (this is for laminar flow)
Pediatrics:
airway resistance in a child’s airway is described by Cote as turbulent flow (d/t crying and distress)
-this is why the text states airway resistance for children is higher (5th power)
2
Q
The trachea and bronchi in infants and children are prone to ________?
A
Collapse
3
Q
Where is most of the resistance in the infant airway?
A
Most of the resistance is in the small airways and bronchi
-d/t small diameter and greater compliance of trachea and bronchi
4
Q
Airway obstruction in pediatrics is mostly related to what factors?
A
Loss of muscle tone in pharyngeal and laryngeal structures.
most pronounced at the hypopharynx at the level of the epiglottis
5
Q
What is the physiologic cause of Laryngospasm?
A
Inspiratory effort which causes longitudinal separation of vocal folds and vestibular folds.
“longitudinal stretching” refers to Anterior-posterior tension/stretching of larynx l/t glottic closure (via vocal cord adduction)
6
Q
What occurs to the glottis and vocal cords during a valsalva maneuver?
A
During valsalva, the exhalation occurs against a closed glottis.
This generates increased intrathoracic pressure
7
Q
What are the medications used for treatment of laryngospasm?
A
IV propofol is primary treatment, followed by increasing VAA and flows
For persistent Laryngospasm:
-succinylcholine: 3 mg/kg IM or 2 mg/kg IV
-atropine with succinlycholine: 0.02 mg/kg IV
8
Q
For pediatric patients with asthma what are some interventions utilized that may prevent intraoperative bronchospasm?
A
Rescue inhaler used on the day of surgery
Maintain any asthma maintenance drug regimen
9
Q
List the characteristics of intraoperative bronchospasm? (7)
A
10
Q
The following EtCO₂ waveform in a pediatric patient would be suggestive of what?
A
Bronchospasm.
Shark fin
-airway obstruction (uneven exhalation)
-no plateau as alveoli may continue emptying late in exhalation
11
Q
A polyphonic wheeze with prolonged expiration and increased respiratory effort would be suggestive of what?
A
bronchospasm
12
Q
What drugs should be utilized for induction to prevent bronchospasm?
A
Ketamine and propofol d/t bronchodilation
Sevo and iso are preferred VA
-Desflurane can l/t increased airway resistance (used as maintenance rather than induction)
13
Q
What are some intraoperative treatments for bronchospasm?
A
14
Q
What should be done to the I:E ratio in the instance of bronchospasm?
A
I:E ratio should increase in bronchospasming patients to minimize air trapping.
increase expiratory time to decrease air trapping
15
Q
What drugs may be needed if unable to break bronchospasm?
A
IV steroids and/or epi
16
Q
What is the pediatric dose of epinephrine for bronchospasm?
A
0.05 - 0.5 mcg/kg q1min as needed
17
Q
The following symptoms are associated with what type of spasm?
A
Laryngospasm
18
Q
The following symptoms are associated with what type of spasm?
A
Bronchospasm
19
Q
Inflammation & edema related to compression of the tracheal mucosa after extubation is known as?
A
Post-extubation Croup
20
Q
What are the risk factors for post-extubation croup?
A
- Larger ETT size
- Changes in position during surgery (any position other than supine)
- Repeated intubation attempts
- Age 1-4 (subglottic portion of airway narrowest in this age group)
- Longer (>1hr) surgeries
- Previous hx of croup
21
Q
What are the treatment options for croup?
A
- Racemic Epi
- Dexamethasone 0.5 mg/kg
22
Q
What type of ETT can be used as prevention of post intubation croup? What are the features of this type of ETT?
A
- Prevention: micro-cuff ETT (high volume/low pressure)
-high volume/low pressure
-elliptical balloon that is placed more distally
-no Murphy eye
-provides more uniform surface contact
23
Q
What is the pediatric dexamethasone dosage for croup?
A
0.5 mg/kg
24
Q
What are the pulmonary consequences of CDH (Congenital Diaphragmatic Hernia) ?
A
CDH inhibits normal lung growth.
-This involves the division of airways and formation of pulmonary vasculature l/t decreased bronchi and alveoli
The resulting decreased surface area for gas exchange cause:
- ↑ PVR
- Primary Pulm HTN
25
Which lung is affected by CDH?
The ipsilateral lung is usually affected
*contralateral may be affected however.
26
Congenital Diaphragmatic Hernia is caused by failure of complete closure of what structures
pleural and peritoneal canals
27
With Congenital Diaphragmatic Hernia the _________ __________ herniate into the _________
abdominal organs; thorax
28
What factors determine the severity of Congenital Diaphragmatic Hernia?
Severity of abnormality determined by:
-In utero timing of herniation
-amount of abdominal contents in thorax
29
Infants with CDH are more likely to have other birth defects. Which two defects were mentioned and what is the occurrence of each?
Congenital Heart Defects: 20-40%
Chromosomal abnormalities: 5-15%
30
The most common form of CDH occurs at the posterolateral _____ ____ _______.
Foramen of Bochdalek
-5x more likely to occur on the left side (80-85% of cases)
31
Foramen of Bochdalek CDH is the largest type and is associated with the greatest degree of pulmonary ________.
hypoplasia
32
2% of infants with CDH have a ___________ type defect, the remaining cases of CDH occur through the _________ __________
- Morgagni (2%)
- esophageal hiatus
33
Which lung will be compressed in left posterolateral CDH?
Left lung (ipsilateral to the CDH)
34
How is CDH usually diagnosed? What are the findings correlated with CDH?
Most cases are diagnosed prenatally via Ultrasound
Findings:
-polyhydramnios
-intrathoracic gastric bubble
-mediastinal shift away from site of herniation
35
How is CDH diagnosed in the antenatal period? What findings are significant for CDH?
Abdominal X-ray
Findings:
-intestinal loops
-abdominal organs in the thorax
-ipsilateral lung compression
36
What are the signs and symptoms seen in babies born with CDH?
37
CDH used to be treated with emergent surgical intervention. Now the primary treatment course is aimed at stabilizing medically and optimizing prior to surgery. What are the various means used to optimize these patients?
-Improve Pulmonary HTN and decrease PVR
-high frequency oscillatory ventilation (small frequent VT, limited PAP, avoid CPAP)
-Vasodilator therapy (inhaled NO)
-Prostaglandin E1 to maintain PDA and reduce RV after load
38
What are the criteria for ECMO use in patients undergoing CDH repair?
Severe cases of lung hypoplasia and pulmonary HTN
-Patients with PaO2 <50 mmHg on 100% FiO2
39
What ventilator changes can we make to improve PVR?
100% FiO2
Hyperventilating
-this induces respiratory alkalosis which l/t ↓ PVR
**↓ CO₂ → Pulmonary Vasodilation**
40
____________ is the major cause of morbidity and mortality in infants undergoing CDH repair without ECMO?
Pulmonary HTN
41
If an infant's stomach is too small to hold herniated abdominal contents from a CDH, what can be used to hold viscera outside of the body? What are the benefits of slowly reintroducing bowel contents back into the abdomen over time?
Silo Pouch
Benefits:
-allows the infant to grow over time and better accommodate the bowels
-prevents the dramatic decrease in lung compliance seen when the bowel contents are reintroduced into a small intraabdominal cavity
42
Is single lung ventilation necessary for CDH repair?
Not necessarily.
Low flow, low pressure CO₂ insufflation on the ipsilateral lung can aid in returning abdominal viscera back where it needs to go.
43
What position will the patient be in for a CDH repair?
Lateral decubitus position with the upper arm positioned for field avoidance.
44
What are the anesthesia management considerations for CDH repair?
Avoid volutrauma (oscillator ventilation)
Avoid Increased PVR
NGT placement prior to induction
-decreased risk of air entering stomach
45
What are the pharmacological anesthesia management considerations for CDH repair?
Avoid N2O
Muscle paralysis (during and after surgery. Remain intubated postop)
**Induction**
-fent 50 mcg/kg
-Roc 1.2 mg/kg or Cisatracurium 2 mg/kg
-Sevo as tolerated
46
Elevated PVR should be avoided in CDH surgeries. How can PVR be lowered during surgery?
Hyperventilation
Narcotics to blunt sympathetic discharge
47
What type of anesthetic is utilized during CDH repair, if oscillator ventilation is used throughout the procedure? Why is this the preferred method of anesthesia delivery?
TIVA with paralysis is used if Oscillatory ventilation is used.
HFOV (high frequency oscillatory ventilation)
-uses low Vt with rapid frequencies (limiting VAA delivery and scavenging)
-TIVA with paralysis provides more precise anesthesia delivery
48
What are some common causes of elevated PVR?
- Hypoxemia
- Acidosis
- Hypothermia
- Hypercarbia
49
What are some commonly used methods to avoid increased PVR in CDH patients?
- Hyperventilation
- Narcotics (SNS blunting)
50
What is meant by the term **blind pouch**
Blind pouch:
-end of esophagus that is closed off/not connected to stomach
51
List and describe the rarest type of tracheoesophageal fistula? This type is often diagnosed later in life and is accompanied by recurrent _________?
Type E TEF (aka H type d/t shape of fistula) is very rare.
-small fistula between esophagus and trachea w/o esophageal atresia (closure)
Late diagnosis: infant can still feed d/t no esophageal atresia
-The patient may suffer from recurrent pneumonia prior to diagnosis (esophageal contents leak into trachea)
52
Which type of Tracheoesophageal Fistula (TEF) is most common?
Type C.
-Proximal esophageal pouch and distal tracheoesophageal fistula
**pouch at the top, fistula 1-2 tracheal rings above carina**
Cote: lists from proximity to carina
-Distal esophageal pouch and proximal tracheoesophageal fistula
53
Tracheoesophageal Fistula (TEF) is usually located where in relation to the carina?
1-2 rings **above** the carina
54
When does Tracheoesophageal Fistula (TEF) occur gestationally? What is the cause of this malformation?
Occurs in 4-5th week of gestation
Cause:
-error in separation of trachea from the floor of the foregut
55
Tracheoesophageal Fistula (TEF) is often associated with VACTERL. What does this acronym stand for?
- **V**ertebral anomalies
- **A**nus imperforate (opening missing or blocked)
- **C**ongenital heart disease
- **T**racheo**E**sophageal fistula
- **R**enal abnormalities
- **L**imb abnormalities
56
How is Tracheoesophageal Fistula (TEF) diagnosed prenatally?
Diagnosed via Ultrasound:
- Polyhydramnios
- Absent/small gastric bubble
-blind end of upper pouch in fetal neck
57
What are the postnatal s/s of Tracheoesophageal Fistula?
-excessive salivation
-choking/coughing
-regurgitation with first feeding l/t cyanosis and/or resp. distress
-distended abdomen (air filling stomach when baby cries)
-inability to pass NGT
58
What are the hallmark s/s of Tracheoesophageal Fistula (TEF) in the postnatal period?
**The 3 C's**
- Choking
- Coughing
- Cyanosis
59
What is the criteria for diagnosis of Tracheoesophageal Fistula (TEF) after birth?
-Inability to pass NG tube into stomach more than 7cm.
Imaging:
-Dilated proximal esophagus with air in conjunctino with air in the distal stomach
-CT or direct visualization via bronchoscopy/endoscopy
60
How will Tracheoesophageal Fistula (TEF) appear on CXR?
Feeding tube coiled in the esophageal pouch (yellow circle)
Large volume of gas in abdomen (arrow)
61
What preoperative intervention should be performed in regards to the proximal pouch?
-A proximal pouch gastric tube should be inserted and secured
-The tube should be placed to continuous suction.
62
What anesthetic airway maneuvers should be avoided prior to surgery for TEF?
- Mask ventilation
- Tracheal intubation
*Likely to exacerbate distention*.
63
What approach is utilized for surgical Tracheoesophageal Fistula (TEF) repair? What position is used to accommodate this approach?
Approach:
Surgical repair can be done via Open thoracotomy
**Right thoracotomy approach which helps avoid the aortic arch**
Thorascopic approach is more common now
Position:
Left Lateral Decubitus
64
How is the right lung collapsed for TEF repair?
Collapsing right lung is needed for exposure:
-Single lung ventilation is not required
-low-flow, low-pressure CO2 insufflation into right pleural cavity
-This increases intrathoracic pressure on the right side
-This compresses the lung tissue by overcoming the negative pleural pressure and collapsing the lung
65
What is the order of the surgical repair of a Tracheoesophageal fistula repair?
Fistula is ligated *first**
-this prevents further air entrapment into the stomach
Primary end to end anastomosis of the esophagus follows ligation
66
Why is it important to keep the infant spontaneously breathing during TEF repair?
Positive pressure breathing can l/t:
-gastric insufflation and potentially gastric rupture
-Increase risk of pneumothorax/barotrauma
-increase aspiration risk (gastric contents forced into lungs via fistula)
67
Where should the ETT tip be placed in TEF patients? What is the best technique to ensure proper placement of ETT?
Tip of the ETT is placed above the carina but distal to the fistula
**fistula usually 1-2 tracheal rings above carina**
Purposefully mainstem upon intubation
↳slowly withdraw ETT while ascultating the left chest until breath sounds heard bilaterally
↳can confirm with fiber optic as well
68
What are some consideration when inducing a patient prior to TEF?
-IV induction is quicker, more stable
-muscle relaxants can optimize intubation
-Gentle mask ventilation with low peak pressures
69
What are some airway considerations for postop TEF patients that remain intubated?
-Frequent ETT suctioning may be required
-After surgical correction: Increasing I:E time to help re-expand alveoli
-Maintain head in neutral position to prevent pulling on esophageal anastomosis
70
Though early extubation can help alleviate pressure on suture lines after TEF repair, many surgeons request post op intubation for multiple days. What are the benefits of intubation in the postoperative phase?
Helps prevent:
-pneumonia
-atelectasis
-emergent reintubation
-perforation of suture lines
71
What types of catheters may be used for postoperative pain following TEF repair?
Epidural catheter from caudal space
-commonly used intraoperatively in TEF repair
Intrapleural catheter
72
Pyloric stenosis is most frequent in __________?
First born males (4:1)
73
What newborn condition is often diagnosed between 2 - 8 weeks of age with non-bilious projectile vomiting?
Pyloric stenosis
74
What is pyloric stenosis?
Hypertrophy/Hyperplasia of muscular layer of pylorus resulting in gastric outlet obstruction.
75
What acid-base imbalance is typical for pyloric stenosis?
Metabolic alkalosis with hypokalemia & hypochloremia
**can lead to metabolic acidosis with chronic vomiting**
76
Why does metabolic alkalosis occur with pyloric stenosis?
-Kidney excretion of HCO₃⁻ to maintain normal blood pH
-Kidney excretion of H⁺, then K⁺ to maintain euvolemia and retain Na⁺.
77
How does Pyloric stenosis affect intake and appetite?
Immediate postprandial vomiting
Infant is hungry between feedings (hungry vomiter)
78
Is pyloric stenosis a medical emergency typically?
No. 24-48 hours are typically taken to correct electrolyte imbalances
79
What tool is used to diagnose pyloric stenosis? What is the hallmark sign of pyloric stenosis?
Pyloric stenosis is diagnosed via ultrasound
Donut sign or Target sign is the definitive sign of pyloric stenosis
80
What is the treatment plan for patients with Pyloric stenosis?
Pyloric stenosis is not a medical emergency
-infants are medically managed to correct electrolyte imbalances (24-48 hours)
-Dextrose IVF for maintenance and electrolyte balance
81
What are some of the criteria that determines readiness for surgery to correct Pyloric stenosis?
Good skin turgor (can also assess fontanels)
UOP 1-2 mL/kg/hour
Na⁺ >135 mEq/L
K⁺ >3.0 mEq/L
Cl- >85 mEq/L
82
What fluids and rate are typically used to correct electrolyte imbalances in patients with pyloric stenosis?
D5 NS with 20 mEq K⁺ @ 10-20 mL/kg/hr
83
How is pyloric stenosis diagnosed? When is pyloric stenosis usually diagnosed?
Commonly with Ultrasound
*rarely dx via barium swallow study and Xray
Today infants are diagnosed fast
-less likely to see severe fluid and electrolyte imbalances
84
How is pyloric stenosis repaired?
Pyloromyotomy: either laparoscopic or open
-open is done via periumbilical incision
85
What are the anesthesia management considerations before and during induction?
Pyloric Stenosis patients are **always full stomachs**
1. preoxygenate with 100% O2
2. Oral gastric placement of Red Rubber catheter before induction to decompress stomach
3. RSI induction
86
What are the steps of suctioning via red rubber cath prior to induction for pyloromyotomy?
-Oral gastric placement of Red Rubber catheter before induction
-turn head to right and apply suction (preoxygenate 100%)
-return head to center position and suction (preoxygenate 100%)
-turn head left and suction (preoxygenate 100%)
**repeat until no more gastric contents**
87
What narcotics are typically used for pyloric stenosis?
Trick question. **No Narcotics**!
88
What are the pediatric doses for induction medications? (Lido, Atropine, Prop, succinylcholine and tylenol)
Lidocaine 1-2 mg/kg
Atropine 0.02 mg/kg
Propofol 2-4 mg/kg
succinylcholine 2 mg/kg
Tylenol 30-40 mg/kg suppository
89
What are the PACU considerations that must be made post pyloromyotomy?
Apnea monitor (for first 24 hours postop)
-post op respiratory depression is common
Monitor for hypoglycemia
-vomiting episodes over prolonged periods before surgery
Analgesia
-if still in pain low dose morphine (0.02-0.03 mg/kg)
90
Why are patients with pyloric stenosis at an increased risk for respiratory depression/apnea?
Pyloric stenosis cause preop alkalosis of CSF (metabolic alkalosis)
-Physiologic response to this alkalosis is **hypoventilation** to increase PCO2
91
What type of fluids are used for hydrating infants post operative for pyloromyotomy (until adequate oral intake occurs)?
Dextrose containing fluids (for calories & glucose).
92
Pyloric stenosis repair necessitates an ______ extubation.
awake
93
What are the main differences between Gastroschisis and Omphalocele?
**Gastroschisis:** herniated viscera and intestines are periumbical (usally right of umbilicus) and lack a membranous sac
**Omphalocele:** emerges from umbilicus (within umbilical cord) and is covered in membranous sac
94
What condition is depicted below? What other congential anamolies are associated with this condition?
Gastroschisis
-Usually not associated with other congenital anomalies
95
What condition is depicted below? What other congential anamolies are associated with this condition?
Omphalocele
-Associated with genetic, cardiac, urologic and metabolic abnormalities
96
What causes gastroschisis?
Gastroschisis results from **occlusion of omphalomesenteric artery** during gestation
97
How is the bowel function affected by presence of Gastroschisis?
Bowel is functionally abnormal
-dilated and shortened bowel
-this is d/t exposure to amniotic fluid in utero and exposure to air after delivery
**exposure to amniotic fluid and air l/t bowel inflammation and edema**
98
What is the cause of Omphalocele? How is the bowel affected by presence of Omphalocele?
Omphalocele results from **failure of the gut to migrate from the yolk sac into the abdomen** during gestation
Bowel Function:
-usually morphologically and functionally normal d/t membranous sac protecting bowel
99
How is perfusion to viscera optimized and fluid loss prevented in patients with either Omphalocele or Gastroschisis?
-Covering mucosa with sterile saline soaked dressings
-Plastic wrap over herniated viscera
-this decreases evaporative loss, prevents heat loss/hypothermia
**hypothermia more prounounced with Gastroschisis**
100
How is the surgical reduction of Omphalocele and Gastroschisis managed?
**Complete surgical reduction:** if the abdomen can accomodate all of the herniated bowel
**Staged Reduction:** Silastic pouch used if unable to reduce all of the bowel on initial surgery
101
Describe the process of staged reduction of Omphalocele and Gastroschisis?
Silastic pouch used to protect bowel that remains outside abdomen
-pouch size decreased with each surgery
-This allows gradual accomodation of abdominal contents into the abdominal cavity
-This gradual reintroduction helps prevent respiratory or organ perfusion compromise that may be seen with increased intraabdominal pressure.
102
What are some signs of bowel edema that may occur during or after surgical reduction of Omphalocele or Gastroschisis?
Bowel edema can l/t:
-renal congestion → decreased urine output, lower extremity congestion and cyanosis (d/t decreased venous return)
-Blood pressure/pulse ox discrepancies between upper and lower extremities
-Intragastric tube pressure measurement of >20 mmHg after primary closure. This pressure can cause abdominal ischemia
103
How does bowel edema affect respiratory system?
Bowel edema can l/t:
-Decreased diaphragm function
-Bilateral lower lobe atelectasis
-Respiratory failure
104
What does the anesthesia management for Omphalocele or Gastroschisis include?
105
What is the goal for Peak Airway Pressure during primary Omphalocele/Gastroschisis closure?
Maintain PAP <25 mmHg during primary closure
106
What may hypotension be a sign of during a Omphalocele or Gastroschisis reduction surgery?
Hypotension may result from increased intraabdominal pressure which impedes venous return.
-BP and/or Pulse Ox on both upper and lower extremity may help identify this early
