General anaesthesia and sedation Flashcards
23.1 A patient will open her eyes in response to voice, speak with inappropriate words and
withdraw to a painful stimulus. Her Glasgow Coma Scale score is
a. 6
b. 7
c. 8
d. 9
e. 10
e. 10
22.2 The Glasgow Coma Score of a patient whose best responses are: opening eyes to pain, making incomprehensible sounds, and withdrawing from pain is
a) 6
b) 8
c) 9
d) 10
e) 12
B) 8
E=2
V=2
M=4
Total= 8
23.1 According to National Audit Project (NAP) 5, the incidence of awareness during general anaesthesia for lower segment caesarean section should be quoted as
a) 1:700
b) 1:3,000
c) 1:8,000
d) 1:19,000
e) 1:36,000
a) 1:670 (or 1:700)
23.1 According to the Fourth Consensus Guidelines for the Management of Post-operative Nausea and Vomiting (PONV) published in 2020, multimodal PONV prophylaxis should be implemented in adult patients
a. For everyone
b. 1 or more RF
c. 2 or more RF
d. 3 or more RF
e. 4 or more RF
b) 1 or more RF
21.1 Predictors of successful awake extubation after volatile anaesthesia in infants include
a. 2mL/kg tidal volume,
b. grimacing
c. coughing
d. RR > 20
b. grimacing
conjugate gaze
facial grimace
eye opening
purposeful movement
tidal volume greater than 5 ml/kg
Source: SPANZA 2019 article
21.1 Predictors of successful awake extubation after volatile anaesthesia in infants include
a. 2mL/kg tidal volume,
b. grimacing
c. coughing
d. RR > 20
b. grimacing
conjugate gaze
facial grimace
eye opening
purposeful movement
tidal volume greater than 5 ml/kg
Source: SPANZA 2019 article
22.1 A risk factor for postoperative nausea and vomiting in adults is age less than
a. 20
b. 30
c. 40
d. 50
e. 60
50
4th consensus guidelines for management of PONV
An awake patient in the post-anaesthesia care unit complains of breathlessness. The FiO2 through the patient’s rebreather mask is 40%. An arterial blood gas taken at the time shows (ABG shown). The alveolar-arterial gradient (in mmHg) is approximately
Blood gas shows:
PaO2 135
PaCO2 48
SpO2 100%
The A-a gradient is:
A. 5
B. 30
C. 60
D. 90
E. 110
D 90
A-a = PAO2 - PaO2
Alveolar air equation gives PAO2
PAO2 = PiO2 - PaCO2 / R
PAO2 = 0.4 x (760 - 47) - 48 / 0.8
so, as PaO2 given as 135
A-a = 228 - 135 = 93
23.1 Causes of exhaled carbon dioxide detection following oesophageal intubation include
all of the following EXCEPT
a. Massive bronchopleural fistula.
b. Carbonated drink.
c. Vigorous bag valve masking previously.
d. Previous gastric insufflation with CO2 for endoscopy.
e. Tracheoesophageal fistula.
A Massive bronchopleural fistula.
Nick Chrimes 2022 - Journal of Anaesthesia
‘Preventing unrecognised oesophageal intubation: a consensus guideline from the Project for Universal Management of Airways and international airway societies’
Causes of exhaled carbon dioxide detection despite oesophageal intubation
No alveolar ventilation occurring
-Prior ingestion of carbonated beverages or antacids
-Gastric insufflation of CO2 for upper gastrointestinal endoscopy
-Prolonged ventilation with facemask or poorly positioned supraglottic airway before attempting tracheal intubation
-Bystander rescue breaths
Some alveolar ventilation potentially occurring
-Tracheo-oesophageal fistula with tube tip proximal to fistula
-Proximal oesophageal intubation with uncuffed tube in a paediatric patient
21.1 In the morbidly obese the induction dose of propofol should be calculated based on
a. Lean body weight
b. Total body weight
c. Ideal body weight
d. Ideal body weight + 70%
Lean Body Weight
For infusion: Adjusted body weight
NDMB: Lean Body weight
Sux: Total body weight
Source: SOBA UK
22.1 The most reliable clinical indicator of opioid-induced ventilatory impairment (OIVI) is decreased
a. Sedation
b. Respiratory rate
SS /GCS
Repeat APMSE
22.1 The gauge pressure on a gas cylinder does NOT necessarily represent the contents remaining if the cylinder is filled with
Nitrous oxide
Nitrous oxide boiling point -88.6C, critical temperature +36C -> so is below critical temp at room temp, therefore exists as a vapour in equilibrium with its liquid phase and is dependent upon pressure applied to it. Pressure gauge not informative – will always read ~52 bar (the pressure at which N2O liquefies at 20C). As vapour is drawn off, N2O moves from liquid to vapour phase, maintaining the equilibrium and same vapour pressure within the cylinder.
To determine contents: cylinder must be weighed and weight of empty cylinder subtracted, then number of moles of N2O in cylinder calculated using Avogadro’s number.
22.2 Which is least likely to cause inaccuracies in pulse oximetry
a) Anaemia
b) Vasoconstriction
c) AF
d) Methaemoglobin
e) Carboxyhaemoglobin
a) Anaemia
No effect
- Fetal haemoglobin (HbF)
- SulphHb
- Bilirubin (absorption peaks are 460, 560 and 600 nm)
- dark skin
Falsely low reading
1. Methaemoglobin (MetHb). The presence of MetHb will prevent the oximeter from working accurately and the readings will tend towards 85%, regardless of the true saturation.
2. Methylene blue. When methylene blue is used in surgery (e.g. parathyroidectomy or to treat methaemoglobinaemia), a short-lived reduction in saturation estimations is seen. Readings may fall by 65% at a concentration of 2-5 mg/kg for between 10 and 60 minutes.
3. Indocyanine green. Use of this dye (e.g. in cardiac output studies) may cause a transient reduction in recorded saturations.
4. A reduction in peripheral pulsatile blood flow produced by peripheral vasoconstriction results in an inadequate signal for analysis.
5. Venous congestion, which may be caused by tricuspid regurgitation, high airway pressures and the Valsalva manoeuvre, may produce venous pulsations which can produce low readings.
6. Venous congestion of the limb may affect readings, as can a badly positioned probe.
7. External fluorescent light in the operating theatre may cause the oximeter to be inaccurate, and the signal may be interrupted by surgical diathermy. Shivering may cause difficulties in picking up an adequate signal.
8. Nail varnish may cause falsely low readings.
Falsely high reading
1. Carboxyhaemoglobin (CoHb). CoHb (haemoglobin combined with carbon monoxide) is registered as 90% oxygenated haemoglobin and 10% desaturated haemoglobin - therefore the oximeter will overestimate the saturation.
Calibration
- Oximeters are calibrated during manufacture and automatically check their internal circuits when they are turned on.
- They are accurate in the range of oxygen saturations of 70% to 100% (+/-2%), but are less accurate under 70%. Below the saturation of 70%, readings are extrapolated.
- The data for calibration came from human volunteer studies, hence it was unethical to allow the saturations to fall below 70%. Due to the shape of the oxyhaemoglobin curve, the saturation starts to fall rapidly at 90%.
Limitations
- The oximeter averages its readings every 10-20 seconds. Hence, they cannot detect acute desaturation. The finger probe has a response time of approximately 60 seconds, whereas the ear probe has a response time of 10-15 seconds.
- The site of application should be checked at regular intervals, as pressure sores and burns have been reported.
- The pulse oximeter only provides information about oxygenation. It does not give any indication of the patient’s carbon dioxide elimination.
20.1 You are asked to review a previously well 48-year-old woman two hours after hysteroscopic myomectomy and endometrial ablation under general anaesthesia. Her observations are: Heart rate 70 /minute, blood pressure 130/80 mmHg, SpO2 98% on 2 litres per minute of oxygen via nasal prongs. She is drowsy but rousable, oriented to person but not to time and place. Her electrolytes show: (List of electrolytes given) The most appropriate treatment is
Na 118, K 3.0, Cr 56, Ur normal.
What is your management?
A. 500ml 0.9% NaCl
B. 3% NaCl 100ml
C. 10mmol KCl
D. Fluid restriction
a) 3% saline 100ml
100ml bolus of 3% saline (should raise serum Na by 2-3
meq/L). If no improvement in neurological symptoms, can
repeat bolus 1-2 more times at 10 minute intervals.
Frusemide only recommended if APO
22.2 A patient is anaesthetised from the awake state to a state of surgical anaesthesia with propofol or a volatile anaesthetic. As the depth of anaesthesia increases, the patient’s electroencephalogram (EEG) will show oscillations that are of
a. low frequency low amplitude
b. low frequency high amplitude
c. high frequency low amplitude
d. high frequency high amplitude
b. low frequency high amplitude
Changes in the electroencephalogram during anaesthesia and their physiological basis
https://academic.oup.com/bja/article/115/suppl_1/i27/234261
Figure 1 shows raw EEG waveforms during isoflurane anaesthesia.
During light anaesthesia:
-amplitude is shallow and frequency is high.
When a higher concentration is administered:
-amplitude deepens and EEG frequency slows.
During deep anaesthesia:
- a ‘burst and suppression’ pattern becomes apparent, characterized by extreme activity, represented by high-frequency, large-amplitude waves (bursts), alternating with flat traces (suppression).
- This pattern, excluding brain ischaemia or other factors, indicates that anaesthesia is too deep. Beyond this, flat traces become dominant and, eventually waveforms are no longer apparent.
During isoflurane, sevoflurane or propofol anaesthesia, this sequence of changes in pattern is almost identical.
The major difference in EEG between the volatile agents (isoflurane or sevoflurane) and propofol is apparent in power in the theta range.
During propofol anaesthesia, theta power remains low regardless of concentration, but during isoflurane or sevoflurane anaesthesia, it increases at surgical concentrations of anaesthesia.
23.1 The next patient on your endoscopy list is a 50-year-old woman who has been scheduled for gastroscopy and colonoscopy under sedation, after unsatisfactory
proceduralist-supervised midazolam and fentanyl sedation in the past. She states that she has egg anaphylaxis and carries an adrenaline (epinephrine) auto-injector.
The most appropriate agent to use for her sedation is
A. Propofol
B. Ketamine
C. Remifentanil
D. Sevofluarane
A
The situation in adults is straightforward: there is convincing evidence that propofol is safe in patients who are allergic to peanut and/or soy and/or egg.
BJA Ed
https://academic.oup.com/bja/article/116/1/11/2566111
21.2 A 30 year old athlete undergoing a knee arthroscopy under general anaesthesia becomes tachycardic intraoperatively. A 12-lead electrocardiogram (ECG) is obtained. The most likely diagnosis is
a) Atrial fibrillation
b) Atrial flutter
c) Sinus tachycardia
d) WPW
d) WPW
Type B pattern
LITFL:
ECG features of WPW in sinus rhythm
-> PR interval < 120ms
-> Delta wave: slurring slow rise of initial portion of the QRS
-> QRS prolongation > 110ms
-> Discordant ST-segment and T-wave changes (i.e. in the opposite direction to the major component of the QRS complex)
-> Pseudo-infarction pattern in up to 70% of patients — due to negatively deflected delta waves in inferior/anterior leads (“pseudo-Q waves”), or prominent R waves in V1-3 (mimicking posterior infarction
Can be left-sided (Type A) or right-sided (Type B), and ECG features will vary depending on this:
Left-sided AP:
produces a positive delta wave in all precordial leads, with R/S > 1 in V1.
(Dominant R Wave in V1)
Sometimes referred to as a type A WPW pattern
Right-sided AP:
produces a negative delta wave in leads V1 and V2.
Sometimes referred to as a type B WPW pattern
Tachyarrhythmias in WPW
There are only two main forms of tachyarrhythmias that occur in patients with WPW
- Atrial fibrillation or flutter.
-> Due to direct conduction from atria to ventricles via an AP, bypassing the AV node - Atrioventricular re-entry tachycardia (AVRT).
-> Due to formation of a re-entry circuit involving the AP
Breakdown of Type A example:
- Sinus rhythm with a very short PR interval (< 120 ms)
- Broad QRS complexes with a slurred upstroke to the QRS complex — the delta wave
- Dominant R wave in V1 suggests a left-sided AP, and is sometimes referred to as “Type A” WPW
- Tall R waves and inverted T waves in V1-3 mimicking right ventricular hypertrophy (RVH) — these changes are due to WPW and do not indicate underlying RVH
- Negative delta wave in aVL simulating the Q waves of lateral infarction — this is referred to as the “pseudo-infarction” pattern
22.1 A patient is anaesthetised from the awake state to a state of surgical anaesthesia with propofol or a volatile anaesthetic. As the depth of anaesthesia increases, the patient’s electroencephalogram (EEG) will show oscillations that are of
Dominant EEG frequency decreases, and amplitude increases with increasing concentrations of anaesthetic. End result is burst suppression
https://academic.oup.com/bja/article/115/suppl_ 1/i27/234261
Figure 1 shows raw EEG waveforms during isoflurane anaesthesia.
During light anaesthesia:
-amplitude is shallow and frequency is high.
When a higher concentration is administered:
-amplitude deepens and EEG frequency slows.
During deep anaesthesia:
- a ‘burst and suppression’ pattern becomes apparent, characterized by extreme activity, represented by high-frequency, large-amplitude waves (bursts), alternating with flat traces (suppression).
- This pattern, excluding brain ischaemia or other factors, indicates that anaesthesia is too deep. Beyond this, flat traces become dominant and, eventually waveforms are no longer apparent.
During isoflurane, sevoflurane or propofol anaesthesia, this sequence of changes in pattern is almost identical.
The major difference in EEG between the volatile agents (isoflurane or sevoflurane) and propofol is apparent in power in the theta range.
During propofol anaesthesia, theta power remains low regardless of concentration, but during isoflurane or sevoflurane anaesthesia, it increases at surgical concentrations of anaesthesia.
22.2 Predictors of difficult sedation (agitation or inability to complete the procedure) of patients undergoing gastroscopy do NOT include
Unknown options but…
Factors associated WITH difficulty during Gastroscopy were younger age, procedure indication, male sex, presence of a trainee, psychiatric history and benzodiazepine and opioid use. Factors associated with difficulty during COLONOSCOPY were younger age, female sex, BMI <25, procedure indication, tobacco, benzodiazepine, opioid and other psychoactive medication use
21.2 The condition in which volatile anaesthesia is least appropriate is
a) Multiple sclerosis
b) Myasthenia gravis
c) Lambert-Eaton syndrome
d) Guillain-Barre syndrome
e) Muscular dystrophy
e) Muscular dystrophy
- rhabdomyolysis risk if given to patients with Duchenne or Becker’s muscular dystrophy
- volatiles safe in all above, and also safe in patient’s with myotonic dystrophy
Malignant hyperthermia
- high mortality uncoupling regulation of RyR1 to SR
Duschenne muscular dystrophy
- fatal rhabdo (hyperkalaemia)
21.1 A patient with C6 tetraplegia is undergoing removal of bladder stones under general anaesthesia. The blood pressure rises to 166/88 mmHg. The appropriate response is to
a. Clonidine
b. Hydralazine
c. Decompress the bladder
d. Fentanyl
e. Deepen your anaesthetic
decompress the bladder
Autonomic Dysreflexia:
- medical emergency characterised by severe hypertension,
- brought on by stimulation below the level of the lesion
Factors affecting the development of ADR:
1. Level of spinal injury
2. Duration of injury
3. Whether injury is complete or incomplete
Pathology:
Stimuli arise from caudal roots below the level of the lesion leading to uncontrolled sympathetic activation below the level of the lesion
○ 80% being due to bladder distension
○ Other triggers include
§ bowel distension
§ acute abdo pathology
§ activation of pain fibres
§ sexual activity
§ uterine contractions
22.2 The most likely side effect observed in the post anaesthetic care unit after the use of dexmedetomidine is
a. Bradycardia
b. hypotension
c. shivering
d. cough
e. sedation
b. hypotension
The use of dexmedetomidine did not increase the duration of PACU LOS but was associated with reduced emergence agitation, cough, pain, postoperative nausea and vomiting, and shivering in PACU. There was an increased incidence of hypotension but not residual sedation or bradycardia in PACU.
https://pubmed.ncbi.nlm.nih.gov/35085107/#:~:text=Conclusions%3A%20The%20use%20of%20dexmedetomidine,sedation%20or%20bradycardia%20in%20PACU
20.1 Perioperative hypothermia down to 35degrees - effect on bleeding:
a) More bleeding with normal INR and APTT
b) More bleeding with normal INR and raised APTT
c) More bleeding with raised INR and normal APTT
d) Unchanged bleeding and normal INR and APTT
e) Unchanged bleeding and elevated INR and APTT
More bleeding with normal INR and APPT
https://academic.oup.com/bja/article/117/suppl_3/iii18/2664400
Bleeding observed at reduced temperatures (33 – 37 °C) often occurs because of defects in platelet adhesion, while at temperatures below 33 °C, both reduced platelet function and coagulation enzyme activity contribute
Also lab INR and APTT are not temperature corrected
21.1 Unsupported ventilation in a non-anaesthetised patient with long-standing tetraplegia is improved when
a) Trendelenberg
b) Reverse Trendelenberg
c) Supine
d) Left lateral
e) Right lateral
C) supine
Vital capacity is increased in the supine position as abdominal wall paralysis permits greater displacement of abdominal contents during caudad diaphragmatic excursion. Patients will benefit from being recovered in the supine position.
Effect of the level of the lesion
Lesions above C3: complete dependence on mechanical ventilation because of phrenic nerve denervation causing complete diaphragmatic paralysis.
Lesions between C3 and C5: variable dependence on ventilatory support because of variable effect on diaphragmatic and accessory muscle function.
Lesions between C6 and C8: they may require intermittent non-invasive ventilatory support. Intact diaphragmatic function and accessory neck muscles enable adequate inspiratory effort. However, intercostals and abdominal wall muscles remain paralysed. Exhalation occurs via passive recoil of the chest wall, and cough is impaired. There is an increased risk of pneumonia because of poor mobilization of lung secretions.
Thoracic injuries: little respiratory compromise; the main problems are attributable to an inefficient cough.
422.1 The current ANZCA guidelines for preoperative fasting of adult patients state that studies have shown that it is safe to administer
a) unlimited clear fluid 2 hours prior
b) 200ml clear fluid 2 hours prior
c) 300ml clear fluid 2 hours prior
d) 400ml clear fluid 2 hours prior
400mls of clear fluids pre op
Safe upper limit - definitely has not not been identified and will vary from patient to patient.
Clear fluids
Water / CHO rich fluids / pulp free fruit juice / clear cordial / black tea and coffee
22.2 A 76-year-old man requires an emergency thoracotomy to treat an expanding haemothorax. He is mildly hypotensive and is not fasted. His plasma electrolytes and haemoglobin are below. The most appropriate strategy to employ to intubate him with a double lumen endotracheal tube is to (use)
K 6.3 Ur 7-ish Cr 174
a. Cisatracurium 0.5mg/kg
b. Rocuronium 1.2mg/kg
c. Suxamethonium 1mg/kg
d. Suxamethonium 0.5mg/kg (?was this an option)
b. Rocuronium 1.2mg/kg
Cis not appropriate for intubation
Sux with K 6.3 is risky. (I’ve never heard of reduced dose)
21.1 You have been asked to anaesthetise a patient with a history of severe depression which has been
well controlled on moclobemide. The most appropriate medications in combination with propofol are
a. Sevoflurane, morphine, phenylephrine
b. Sevoflurane, pethidine, phenylephrine
c. Midazolam, fentanyl, ephedrine
d. sevoflurane, oxycodone, ephedrine
a. Sevoflurane, morphine, phenylephrine
Moclobemide = MAOi
23.1 Desufflation after surgical pneumoperitoneum is NOT associated with an increase in
a) SVR
b) CI
c) EF
d) preload
e) LV work
a) SVR
21.2 A man who had successful treatment of a germ cell tumour ten years ago presents for laparoscopic appendectomy. Your intraoperative management should consider
a) Lung protective ventilation
b) Oncoanaesthesia
c) Lowest FiO2 possible
d) MAP 60
c) Lowest FiO2 possible
Bleomycin
Bleomycin is a particularly important chemotherapy drug for the anaesthetist to be aware of.
Bleomycin is often used to treat germ cell tumours and Hodgkin’s disease in a curative setting.
The major limitation of bleomycin therapy is the potential for subacute pulmonary damage that can progress to life-threatening pulmonary fibrosis.
Pulmonary toxicity occurs in 6–10% patients and can be fatal.
Exposure to high-inspired concentration oxygen therapy, even for short periods, as experienced during anaesthesia, is often implicated in causing rapidly progressive pulmonary toxicity in patients previously treated with bleomycin.
These claims have been considered controversial by some, but it is the authors’ recommendation that any patient previously exposed to bleomycin therapy should be treated as high risk, and summary guidance regarding oxygen therapy is shown:
20.1 The maximum fraction of inspired oxygen that can be prescribed with a Venturi mask is
a) 30%
b) 40%
c) 50%
d) 60%
e) 70%
c) 60%
21.1, 22.2 Intraoperative lung protective ventilation strategies include all of the following EXCEPT
A. Vt 6-8ml/kg
B. Patient titrated PEEP
C. Recruitment manoeuvre
D. I:E ratio 1:3
I:E ration 1:3
BJA Lung-protective ventilation for the surgical patient: international expert panel-based consensus recommendations:
An expert consensus was reached for 22 recommendations and four statements.
The following are the highlights:
(i) a dedicated score should be used for preoperative pulmonary risk evaluation; and
(ii) an individualised mechanical ventilation may improve the mechanics of breathing and respiratory function, and prevent PPCs.
The ventilator should initially be set to a tidal volume of 6–8 ml kg−1 predicted body weight and positive end-expiratory pressure (PEEP) 5 cm H2O.
PEEP should be individualised thereafter.
When recruitment manoeuvres are performed, the lowest effective pressure and shortest effective time or fewest number of breaths should be used.
Inspiratory/expiratory ratio:
Several studies have compared prolonged inspiratory-to-expiratory (I:E) ratios to the 1:2 ratio commonly used during mechanical ventilation.
An I:E ratio of 1:1, which has been characterised as providing a ‘balanced stress to time product’, was associated with attenuation of lung damage.
Prolonged I:E ratio increases mean airway pressure and concomitantly reduces peak airway pressure.
Studies using prolonged inspiratory times have described beneficial effects, including increased CRS and PaO2, lower alveolar–arterial gradient, and reduced inflammatory markers.
Given the lack of evidence for a clear benefit of a specific I:E ratio, no recommendation was offered by the panel.
However, the panel noted that optimisation of inspiratory time for individual patients can be achieved by monitoring parameters, such as oxygenation, CRS, and ΔP.
Intraoperative FIO2
Increased FIO2 during mechanical ventilation is administered to prevent or correct hypoxaemia, but may result in hyperoxia.
The negative effects of hyperoxia are not clear, but it has been suggested that it may increase oxidative stress, peripheral vascular and coronary artery vasoconstriction, decrease cardiac output, increase resorption atelectasis, and increase the rate of PPCs.
Recommendations for optimal use of oxygen and current evidence regarding the association between hyperoxaemia and clinically relevant outcomes during intraoperative mechanical ventilation are lacking.
Few studies have revealed a protective effect of hyperoxaemia, some report an association with mortality, whilst others show no association with clinically relevant outcomes.
Therefore, in the absence of evidence, the most prudent course of action during mechanical ventilation is to maintain normoxaemia.
SpO2 monitoring can assist in the detection of hypoxaemia, but during oxygen therapy SpO2 cannot detect hyperoxia.
Whilst SpO2 monitoring reduces the incidence of hypoxaemia, it does not improve the overall patient outcomes and does not reduce morbidity and mortality.
Therefore, once the airway is secured, FIO2 should be set to ≤0.4 with the goal of using the lowest possible FIO2 to achieve normoxia (or SpO2 ≥94%)
Unnecessarily high FIO2 should be avoided.
Administering lower FIO2 will not only decrease the risk of hyperoxia, but will also reduce the masking effect of oxygen therapy and allow for earlier diagnosis of gas-exchange impairment.
21.2 A 30-year-old man with morbid obesity (body mass index [BMI] 55 kg/m2) presents for middle ear surgery. The most appropriate bolus dose of propofol for induction should be based on
a) IBW
b) TBW
c) ABW
d) LBW
e) PBW
d) LBW
22.2 A patient under general anaesthesia monitored with transcranial cerebral oximetry has a decrease in their cerebral oxygen saturation. This is likely to be improved by an increase in all of the following EXCEPT
A. Increasing blood pressure
B. Deepening anaesthesia
C. Increased minute ventilation
D. Transfusion
C. Increased minute ventilation
Cerebral blood flow
Cardiac output
Acid–base status
Major haemorrhage
Arterial inflow/venous outflow obstruction
Oxygen content
Haemoglobin concentration
Haemoglobin saturation
Pulmonary function
Inspired oxygen concentration
Inspired oxygen concentration
23.1 The technique of airway pressure release ventilation
a. Has a prolonged expiratory time
b. Augments cardiac output in hypovolaemic patients
c. Results in reduced mean airway pressures
remembered options
Airway pressure release ventilation (APRV) is an open-lung mode of invasive mechanical ventilation mode, in which spontaneous breathing is encouraged.
APRV uses longer inspiratory times; this results in increased mean airway pressures, which aim to improve oxygenation.
Brief releases at a lower pressure facilitate carbon dioxide clearance.
The terminology and methods of initiation, titration, and weaning are distinct from other modes of mechanical ventilation.
The use of APRV is increasing in the UK despite a current paucity of high-quality evidence
high intrathoracic pressure decreases the transmural left ventricular pressure, reducing the work of contraction and increasing cardiac output. In the context of hypoxaemia, a mode of mechanical ventilation that improves arterial oxygenation will improve myocardial oxygen delivery, myocardial function and cardiac output. As APRV is a spontaneous breathing mode, in addition to the benefits of spontaneous ventilation, reduced doses of sedative drugs can often be used, with subsequent reduction of requirement for vasoactive drugs and improvement in haemodynamic state.
Airway pressure release ventilation (APRV) is an open-lung mode of invasive mechanical ventilation mode, in which spontaneous breathing is encouraged. APRV uses longer inspiratory times; this results in increased mean airway pressures, which aim to improve oxygenation
https://www.bjaed.org/article/S2058-5349(19)30178-7/fulltext
https://derangedphysiology.com/main/required-reading/respiratory-medicine-and-ventilation/Chapter%20518/airway-pressure-release-ventilation-aprv-ards
22.1 Maintaining a CO2 pneumoperitoneum at a pressure of 15 mmHg is most likely to lead to
a) Lactic acidosis
b) Decreased arterial blood pressure
c) Decreased heart rate
d) Increased CVP
e) Increased renal blood flow
f) Increased SVR
f) Increased SVR
22.1 According to the ‘Fourth Consensus Guidelines for the Management of Postoperative Nausea and Vomiting (PONV)’ published in 2020, multimodal PONV prophylaxis should be implemented in adult patients
a. For everyone
b. 1 or more RF
c. 2 or more RF
d. 3 or more RF
e. 4 or more RF
b. 1 or more RF
In this iteration of the PONV guideline, one of the major changes is that we now recommend the use of multimodal prophylaxis in patients with one or more risk factors. This decision was made due to the concern over inadequate prophylaxis as well as the availability of antiemetic safety data.
20.2 In the morbidly obese the induction dose of propofol should be calculated based on
a) Lean body weight
b) Total body weight
c) Ideal body weight
d) Ideal body weight + 70%
e) Adjusted body weight
a) Lean body weight
FROM SOBA:
LBW exceeds IBW in obese and plateaus at ~100kg in men and ~70kg in females
IBW used to calculate the adjusted body weight for maintenance infusion of propofol (IBW +40%).
IBW calculated using Broca formula (Ht in cm - 100; Ht in cm =105; as optimal weights for men and women respectively in kg)
22.2 A 34-year-old for a diagnostic laparoscopy has a height of 158 cm and a weight of 120 kg (BMI 48 kg/m2). For induction of anaesthesia, appropriate drug dosing includes
a) Fentanyl based on TBW
b) Rocuronium based on LBW
c) Propofol induction based on ABW
d) Propofol infusion based on LBW
e) Suxamethonium based on IBW
b) Rocuronium based on LBW
23.1 Anaesthesia-induced rhabdomyolysis differs from malignant hyperthermia in that it is NOT
a. Reduced Myoglobinaemia
b. Less increase in ETCO2
C. Less muscle rigidity
a. Reduced Myoglobinaemia
Repeat but its not myoglobinuria it was myoglobinaemia
- There is NOT reduced myoglobinuria with AIR compared to MH (both have myoglobinuria)
- There IS less increase in ETCO2
- There IS less muscle rigidity
20.1
a) Gas trapping
b) Patient triggering
c) COPD
d) Circuit leak
c) gas trapping
Specific features of increased airway resistance seen here are:
High peak airway pressure, but a normal plateau pressure
Slow return of the flow-time curve to baseline
The flow-time curve does not reach baseline (indicating that emptying is incomplete)
20.1 In planning the induction of anaesthesia in a morbidly obese patient, the total body weight should be used to calculate the dose of
A Suxamethonium
B Propofol
C Thiopentone
D Rocuronium
a) Suxamethonium
The technique of airway pressure release ventilation
a. Has a prolonged expiratory time
b. Augments cardiac output in hypovolaemic patients
c. Results in reduced mean airway pressures
none of the remembered options
Airway pressure release ventilation (APRV) is an open-lung mode of invasive mechanical ventilation mode, in which spontaneous breathing is encouraged.
APRV uses longer inspiratory times; this results in increased mean airway pressures, which aim to improve oxygenation.
Brief releases at a lower pressure facilitate carbon dioxide clearance.
The terminology and methods of initiation, titration, and weaning are distinct from other modes of mechanical ventilation.
The use of APRV is increasing in the UK despite a current paucity of high-quality evidence
high intrathoracic pressure decreases the transmural left ventricular pressure, reducing the work of contraction and increasing cardiac output. In the context of hypoxaemia, a mode of mechanical ventilation that improves arterial oxygenation will improve myocardial oxygen delivery, myocardial function and cardiac output. As APRV is a spontaneous breathing mode, in addition to the benefits of spontaneous ventilation, reduced doses of sedative drugs can often be used, with subsequent reduction of requirement for vasoactive drugs and improvement in haemodynamic state.
Airway pressure release ventilation (APRV) is an open-lung mode of invasive mechanical ventilation mode, in which spontaneous breathing is encouraged. APRV uses longer inspiratory times; this results in increased mean airway pressures, which aim to improve oxygenation
https://www.bjaed.org/article/S2058-5349(19)30178-7/fulltext
https://derangedphysiology.com/main/required-reading/respiratory-medicine-and-ventilation/Chapter%20518/airway-pressure-release-ventilation-aprv-ards
The ventilator waveforms shown represent (actual image from exam)
a) Triggered breaths
b) Bronchospasm
c) Obstructive pattern
d) Gas trapping
C) Obstructive Pattern
https://thoracickey.com/ventilator-graphics/
Image 9.6
You have induced a 20-year-old male for appendicectomy with propofol, fentanyl and suxamethonium. You are maintaining anaesthesia with oxygen, air and sevoflurane. His heart rate has climbed to 150 /minute, the ETCO2 is 50 mmHg and his temperature is 40°C.
After turning off the sevoflurane, you should
a) Commence TIVA
b) Give dantrolene 2.5mg/kg
c) Allocate task cards
d) Start active cooling
e) Remove vaporiser
e) Remove vaporiser
https://anaesthetists.org/Portals/0/PDFs/Guidelines%20PDFs/Guideline%20Malignant%20hyperthermia%202020.pdf?ver=2021-01-13-144236-793
as per guidelines, see link and attached image
As per anaesthetic crisis manual
1. Call for help, communicate and delegate
2. Stop any volatile and remove vaporiser
3. Allocated task cards
4. Give dantrolene
5. Hyperventilate with 100% high flow oxygen
6. Use activated charcoal filters on both limbs
7. Maintain anaesthesia with TIVA
8. Insert IAL +/- CVC
9. Actively cool if temperature > 38.5
10. Treat associated hyperkalaemia, acidosis, arrhythmias
An adult patient is administered a target controlled propofol infusion for more than 30
minutes with a constant effect-site target of 4 mcg/ml propofol plasma concentration.
Compared to the Schnider model, the propofol dose given by the Eleveld model will be a
a) Smaller bolus lower infusion rate
b) Smaller bolus hihger infusion rate
c) Larger bolus lower infusion rate
d) Larger bolus highier infusion rate
e) Smaller bolus same infusion rate
c) Larger bolus lower infusion rate
https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/anae.13345
https://journals.lww.com/anesthesia-analgesia/fulltext/2014/06000/a_general_purpose_pharmacokinetic_model_for.12.aspx
