Anaesthetics Flashcards
(29 cards)
NICE pre-operative guidelines: summarise NICE guidelines on preoperative investigations
• PRE-OPERATIVE INVESTIGATIONS depend on patient co-morbidities and
medications, the type of surgery (including haemorrhage risk) and setting (elective or emergency)
• Consider existing medicines taken by patient when considering pre-operative tests
• Pregnancy tests
o Ask females if there is a chance of pregnancy
o If possible, make patient aware of risks of anaesthetic to fetus, and ask if they would like a pregnancy test. Document.
• Sickle cell disease
o Ask if patient has SCD or FH of SCD
o If they are known to have SCD, liaise with their specialist
• HbA1c testing
o Offer this to people with known diabetes having surgery if they haven’t been tested in last 3 months
• Urine tests
o Consider MSU sample if UTI suspected, and if this can influence decision on operating
• CXR: do not routinely offer before surgery
• Echo: do not routinely offer before surgery
o Consider if patient has heart murmur and cardiac symptom OR signs of HF
o Before echo, carry out ECG
Peri-operative risk scoring systems: summarise common peri-operative risk scoring systems (ASA and POSSUM)
The benchmark for functional limitation is usually two flights of stairs
POSSUM scoring is usually used for risk prediction pre-operatively
o Enter patient physiological
and operative variables e.g. age, BP, HR
o Gives mortality and morbidity score
o Helps inform risk discussion with patient
o Those with over 5% mortality risk should go to HDU/ITU post-op
ASA Scoring
o ASA 1 : Healthy patient
o ASA 2 : Mild systemic disease, no functional limitation
o ASA 3 : Moderate systemic disease, have functional limitation
o ASA 4 : Severe systemic disease that is a constant threat to life.
o ASA 5 : Moribund patient. Unlikely to survice 24 hours, with or without treatment
o Postscript E indicates emergency surgery
Peri-operative disease management: explain the principles of peri-operative management of medical co-morbidities, including diabetes mellitus, hypertension, ischaemic heart disease, asthma, chronic obstructive pulmonary disease (COPD), patients on anti-coagulant medications and sickle cell disease
For co-morbidities, it’s about disease optimisation and control
• For DM, insulin sliding scale is not usually given to NIDDM – this will usually cause hypoglycaemia in these patients. Those that are IDDM, it depends on severity whether a sliding scale is used or not.
For sliding scales, nurses must monitor BM carefully.
• For HT, find out what their NORMAL BP is – different for everyone
• For IHD, if symptomatic/ECG anomaly, refer to cardiologist
• Anti-coagulants: depends why, e.g. for AF, can stop. For heart valve, must keep.
Day Surgery: recall the criteria for the suitability of patients for day stay surgery
Social - Patient consent, carer, home setup
Medical - Fitness, stable chronic, obesity not preclude
Surgical - Complication risks, controllable post op symptoms, mobile
Safety - Nil by mouth policy: explain the principles of nil by mouth policy before surgery
This is done to reduce risk of ASPIRATION
• Usual guidance: food stopped at 6 hours, water stopped at 2 hours
Caveats to this include reflex, obesity, slow gastric transit (e.g. trauma) – require earlier stop
Safety - Transfusion reporting: recognise the importance of reporting blood units administered to the transfusion lab
It is important to report units administered to the transfusion lab
Respiratory - Ventilation: compare the differences between spontaneous ventilation and positive pressure ventilation
• Spontaneous ventilation: this can be done without ventilatory support (patient breathing themselves spontaneously) or be integrated with mechanical ventilation (assisted spontaneous breathing)
• Natural spontaneous ventilation occurs when the respiratory muscles, diaphragm and intercostal muscles pull on the rib cage open, creating a negative inspiratory pressure.
This leads to lung expansion and the pulling of air into the alveoli allowing gas exchange.
• Whereas, in positive pressure ventilation, there is compressed air entering at the alveolar level for gas exchange.
• The key difference is that in spontaneous ventilation, air is pulled into the lungs but in mechanical ventilation, air is pushed into the lungs.
Respiratory - Anaesthetic emergencies: recall the assessment and management of anaesthetic emergencies, including asthma, pneumothorax, haemothorax, anaphylaxis and foreign body aspiration
ASTHMA
o Management of severe bronchospasm outside of theatre i.e. a patient requiring surgery. Use acronym O SHIT M
o O2: start high flow oxygen and gain IV access
o Salbutamol nebulized 2.5-5mg
o Hydrocortisone: 100mg Iv 6 hrly or prednisolone orally 40-50mg/day
o Ipratropium nebulized 0.5mg 4-6hrly, add IV salbutamol if not responding
o Theophylline/aminophylline
o Magnesium 2g IV over 20mins
o Note: in extreme conditions (decreasing conscience levels), can use adrenaline
ANAPHYLAXIS
o Triggers can be nuts, food allergy, stings, antibiotics
o To recognise: signs of shock (pale, clammy), tachycardic, hypotensive (faint, dizzy, collapse), rashes, swelling, diarrhea, vomiting, can cause ECG changes and cardiac arrest
o Key treatment: lift leg up, call for help, give adrenaline
Respiratory - Observations: recall the measurement and normal values of physiological parameters, including pulse oximetry, capnography and blood gas results
• Pulse oximetry measures oxygen saturation – normal: 94-100%
• Capnography: measures concentration of partial pressure of CO2
Normal in arterial blood: 35-45mmHg
Normal in venous blood: 40-50mmHg
Circulation - Blood pressure monitoring: recall the indications for non-invasive and invasive monitoring
• Non-invasive: routine obs
• Invasive: used in ICU and operating theatre. Involves direct measurement of arterial pressure by inserting a cannula needle in an artery
Useful in patients likely to display sudden changes e.g. vascular surgery, in those who require close control of BP e.g. head injured patients, or in patients receiving drugs to maintain BP
Allows accurate readings at very low pressure e.g. in shocked patients
More comfort for those who will require BP monitoring for long time e.g. ICU
Arterial cannula is also convenient for ABG sampling
Circulation - Intravenous fluids: explain the rationale of fluid administration and the difference between colloids and crystalloids
- To replace lost volume
- Permissive hypotension
- This is the concept that argues giving lower fluid resuscitation
- Allow SBP to fall enough to avoid severe blood loss but keep high enough to maintain perfusion. The goal is to avoid disruption of an unstable clot by higher pressures and worsening of bleeding (don’t pop the clot)
- There are two main types of volume expanders: crystalloids and colloids
- Crytalloids are aqueous solutions of mineral salts e.g. normal saline
- Colloids contain larger insoluble molecules such as gelatin- have high osmotic pressure in the blood so should theoretically increase intravascular volume more, but not evidence to suggest colloids are better e.g. FFP
Pain relief - Multimodal analgesia: recall the principles of multimodal analgesia
• Multimodal analgesia is a pharmacologic method of pain management which combines various groups of medications for pain relief. This is needed for acute postoperative pain management due to adverse effects
• There are two types of chronic pain: neuropathic and nociceptive
Neuropathic pain is due to damage/disease affecting somatosensory nervous system – affects the nerves or CNS
Nociceptive pain is due to damage to body tissue causing stimulation of the nociceptive receptors. This can be further divided in to visceral and somatic pain.
• Analgesic classification
o Simple analgesics
Paracetamol (acetaminophen)
Anti-inflammatory medicines: diclofenac, ibuprofen
o Opioids
Mild: codeine
Strong: morphine, pethidine, oxycodone
o Others: tramadol, tricyclic antidepressants, anticonvulsants, ketamine, LA
Circulation - Blood transfusion: recall the triggers for giving a blood transfusion
Is the patient anaemic and haemodynamically stable (is the Hb >90g/L)
If no and patient has :
o Severe sepsis <6 hours from onset aim for Hb 90-100 g/L
o Severe sepsis >6 hours from onset (with evidence of tissue hypoxia) aim for Hb >70 g/L
o Traumatic brain injury with evidence of delayed cerebral ischaemia aim for Hb > 90 g/L
o Subarachnoid haemorrhage aim for Hb 80-100 g/L
o ACS aim for Hb 80-90 g/L
o Stable angina aim for >70 g/L
Pain relief - Pain: summarise approaches to the management of acute and chronic pain
Paracetamol
o Advantages - cheap, safe, can be given PO, IV or PR, good for mild pain and moderate-severe pain (with other drugs)
o Disadvantages - liver damage in overdose
Anti inflammatory medicines
o Aspirin, ibuprofen, diclofenac
o Advantages - cheap, safe, good for nociceptive pain
o Disadvantages - gastrointestinal and renal side effects
Codeine
o Advantages - cheap, safe, good for mild-moderate acute nociceptive pain
o Disadvantages - constipation, not good for chronic pain, misunderstandings about addiction
Morphine
o Advantages - cheap, safe, can be given PO, IV, IM, SC, effective if given regularly, good for moderate-severe nociceptive pain and chronic cancer pain
o Disadvantages - constipation, respiratory depression in high dose, misunderstandings about addiction, controlled drug
Pethidine
o Advantages - good for severe acute nociceptive pain
o Disadvantages - Controlled drug, more frequent dosage than morphine, breakdown product causes convulsions, not good for chronic pain
Tramadol
o Weak opioid effect plus inhibitor of serotonin and noradrenaline reuptake
o Advantages - less respiratory depression, can be used with opioids and simple analgesics, not a controlled drug
o Disadvantages - Nausea and vomiting
Amitryptyline
o Tricyclic antidepressant
o Increases descending inhibitory signals
o Advantages - cheap, safe in low dose, good for neuropathic pain, also treats depression and poor sleep
o Disadvantages - Anticholinergic side effects (e.g. glaucoma, urinary retention)
Anticonvulsant drugs
o Carbamazepine, sodium valproate, gabapentin
o Good for neuropathic pain
Pain relief - Anti-emetic drugs: recall dosage, mode of administration; indications and contraindications of common anti-emetic drugs
Most effective combination = ondansetron + dexamethasone
• Ondansetron
o Mechanism of action - 5HT3R-antagonist
o Side effects - Bradycardia, Long QT syndrome
o Dose - 4-8mg TDS PO/IV
• Cyclizine
o Mechanism of action - H1R-antagonist
o Side effects - Tachycardia, anti-cholinergic
o Dose - 50mg TDS PO/slow IV/IM
• Dexamethasone
o Mechanism of action - corticosteroid
o Side effects - Hyperglycaemia, transient perineal ‘burning’
o Dose - 4-8mg BD/IV
• Metoclopramide
o Mechanism of action - Central DA2 R antagonist
o Side effects - Extrapyramidal side effects (e.g. tremor, slurred speech, dystonia, anxiety)
o Dose - 10mg TDS PO/IV
• Prochlorperazine
o Mechanism of action - DA anatgonist
o Side effects - Extrapyramidal side effects (e.g. tremor, slurred speech, dystonia, anxiety), long QT syndrome
o Dose - 12.5mg BD/IM
Pain relief - Regional analgesia/anaesthesia: explain the rationale and management of regional analgesia/anaesthesia
- Includes spinal anaesthesia (subarachnoid block), epidural anaesthesia, and nerve blocks
- During childbirth, including caesareans
- During and after some types of surgery
- Steroid medication to treat back or leg pain caused by sciatica or a slipped (prolapsed) disc.
Pain relief - Analgesic drugs: recall dosage, mode of administration, indications and contraindications of common analgesic drugs
Alfentanil - 10 mcg/kg
Fentanyl - 1 mcg/kg
Morphine - 0.1 mg/kg
Remifentanil - infusion 15-45 mcg/kg/hr
Airway - Adjuncts/Devices: recognise various airway adjuncts/devices and the indications for their use, including bag mask ventilation, oropharyngeal airways, supraglottic airways and endotracheal tubes
Oropharyngeal Airway
o Makes it easier to push air into lungs – moves tongue out the way
o Put it in back to front and twist
o Size from corner of mouth to angle of mandible
Bag-mask-valve
o Can only be used on someone who is apnoeic (not breathing spontaneously)
Endotracheal Airway
o Definitive airway – cuff in trachea, makes sure it stays in place when you inflate cuff
iGel o Supraglottic device o No cuff – not definitive o Sits above level of the vocal chords o Has a gastric port – reduces risk of aspiration
Emergence: recognise the requirements for emergence from anaesthesia and the indications for ongoing sedation
Before emergence patients should have stable hemodynamic parameters, a patent airway, have adequate ventilation, and oxygenation
Emergence- Sedation: explain the differences between general anaesthesia and sedation
General anaesthetic: Complete loss of consciousness
Sedation: A state somewhere between being very sleepy, being relaxed in consciousness, and yet not unconscious. Do not feel pain, but are aware of what is going on around them.
Recovery - Observations: recall the observations measured in recovery
- Baseline Observations including, RR, Respiratory effort, SpO2, HR, BP and Temperature
- Oxygen requirements
- IV Fluids
- Analgesia
- Urine Output
- Reportable Blood Loss
- Assessment of Wound Sites / Dressings
- Presence of drains and patency of same
- NGT In situ
- Sedation Score (AVPU, Michigan sedation score or formal GCS as indicated)
- Pain Score
- Nausea Score
Recovery - Discharge: recall the criteria for discharge from recovery
- Level of consciousness
- Physical ability
- Haemodynamic stability
- Respiratory stability
- Oxygen saturation status
- Post-operative pain assessment
- Post-operative emetic symptoms
Recovery - Levels: explain the various levels of postoperative recovery including HDU/ICU settings
Different levels and normally work in a step-down model
ICU = one on one nursing care
HDU = one on two nursing care
Recovery - Hand-over techniques: explain effective staff hand-over techniques
SBAR framework: used to clearly + concisely transfer info between HCPs esp – Communicate critical info in 4 steps
o Situation - ID who you are, ID pt, purpose of call, ID Dr you are calling
o Background - Reason for admission/ call, relevant Hx, BG info, current status “eviscerated bowels, multiple stab injuries”
o Assessment - vital signs, contraction pattern, clinical impression. “they think he’s going to lose his left arm”
o Recommendation - explain specifically what you need/ request for guidance + time frame, clarify expectations “you’d better call your senior” other types of immediate action should also be communicated here e.g. going into surgery
