Monitoring in Anaesthesia (CNS, CVS, Respiratory) MCQs

Anaesthesia · 33 free questions with answers & explanations.

1. Bispectral Index (BIS) monitoring of anaesthetic depth is based on processing of which signal?
2. Pulmonary artery catheter (Swan-Ganz) thermodilution measures cardiac output. The Fick principle can also calculate cardiac output if which three values are known?
3. Bispectral index (BIS) monitoring is used to titrate depth of anaesthesia. A BIS value in which range indicates an adequate level of general anaesthesia with minimal risk of awareness?
4. Pulmonary artery catheter (PAC) derived mixed venous oxygen saturation (SvO2) decreases in all of the following conditions EXCEPT:
5. Near-infrared spectroscopy (NIRS) monitoring of cerebral oximetry (rSO2) provides a regional estimate of cerebral oxygen saturation. A sustained decrease in rSO2 of more than what percentage from baseline is considered a significant intraoperative threshold requiring intervention?
6. The Stewart-Hamilton equation is used to calculate cardiac output by thermodilution. Which technical error will falsely INCREASE the calculated cardiac output?
7. The Bispectral Index (BIS) monitor displays a value of 40 during general anaesthesia. What does this indicate, and what BIS range is targeted for anaesthetic maintenance?
8. Pulmonary artery catheter (PAC) thermodilution measures cardiac output. A sudden decrease in ETCO2 from 38 to 15 mmHg during a total hip replacement procedure should prompt immediate consideration of which catastrophic complication?
9. Near-infrared spectroscopy (NIRS) cerebral oximetry provides regional cerebral oxygen saturation (rSO2). What rSO2 threshold below baseline warrants immediate corrective action to prevent cerebral ischaemia?
10. Oesophageal Doppler monitoring during major surgery provides which haemodynamic variable that guides fluid optimisation?
11. The Bispectral Index (BIS) monitor processes the EEG to generate a dimensionless number (0–100). A BIS value of 40–60 corresponds to:
12. Pulmonary artery catheter (Swan-Ganz catheter) measures pulmonary artery occlusion pressure (PAOP/wedge pressure) as an estimate of left ventricular end-diastolic pressure. PAOP may overestimate LVEDP in which of the following conditions?
13. Capnography shows an end-tidal CO2 waveform with an ascending phase slope (phase 2) that is nearly vertical in a normally ventilated patient. This changes to a gradual upward slope on the following case. The MOST likely explanation for the sloped phase 2 is:
14. Near-infrared spectroscopy (NIRS)-based cerebral oximetry measures regional cerebral oxygen saturation (rSO2). During carotid endarterectomy under general anaesthesia, a decrease in ipsilateral rSO2 by what threshold is the recommended indication for shunt placement?
15. The bispectral index (BIS) monitor displays a value of 75 in a patient receiving total intravenous anaesthesia with propofol and remifentanil. The anaesthetist increases the propofol infusion. The BIS is a processed EEG parameter. Which EEG feature drives a HIGH BIS value (indicating wakefulness)?
16. Pulmonary artery occlusion pressure (PAOP/PAWP) normally reflects left atrial pressure and, by extension, left ventricular end-diastolic pressure (LVEDP). In which clinical condition does PAOP OVERESTIMATE LVEDP?
17. Near-infrared spectroscopy (NIRS) cerebral oximetry shows a drop in regional cerebral oxygen saturation (rSO2) from baseline 68% to 52% during carotid endarterectomy after cross-clamping. The threshold value below which intervention is recommended is:
18. Oesophageal Doppler monitoring is used intraoperatively to guide fluid therapy. The corrected flow time (FTc) of 0.28 seconds is measured during passive leg raising. What does this value indicate and what is the appropriate response?
19. Bispectral Index (BIS) monitoring is being used during TIVA with propofol. The BIS value suddenly increases from 40 to 72 despite an unchanged propofol infusion rate. Which is the MOST likely explanation?
20. During laparoscopic cholecystectomy, EtCO2 rises from 35 to 52 mmHg despite unchanged ventilator settings at 30 minutes. The arterial CO2 is confirmed at 55 mmHg. Which is the MOST likely cause?
21. The principle of near-infrared spectroscopy (NIRS) for cerebral oximetry monitoring during cardiac surgery is based on:
22. Bispectral index (BIS) monitoring is used to assess depth of anaesthesia. A BIS value of 40–60 during maintenance of general anaesthesia corresponds to:
23. Pulmonary artery catheter (PAC/Swan-Ganz catheter) wedge pressure (PAWP) of 18 mmHg in a ventilated post-cardiac-surgery patient correlates with which filling status, and at what PAWP does pulmonary oedema reliably occur?
24. Bispectral Index (BIS) monitoring is used intraoperatively. A BIS value of 40 is recorded during general anaesthesia. What does this indicate?
25. Which cardiac monitoring method provides the most accurate non-invasive measurement of cardiac output in the operating theatre?
26. A capnograph waveform shows a slanted rather than flat expiratory plateau (shark-fin pattern) in a mechanically ventilated patient. What is the diagnosis?
27. Train-of-four (TOF) monitoring uses four supramaximal stimuli at 2 Hz. A TOF ratio of 0.7 indicates:
28. The Bispectral Index (BIS) monitor provides a dimensionless number from 0–100 reflecting depth of anaesthesia. A BIS value of 40–60 corresponds to:
29. During cardiac surgery on cardiopulmonary bypass, cerebral oximetry (rSO2) by near-infrared spectroscopy (NIRS) drops from 68% to 48%. Which intervention should be performed FIRST?
30. The bispectral index (BIS) monitor measures processed EEG signals to assess depth of anaesthesia. A BIS value of 40–60 corresponds to which clinical state?
31. Pulse oximetry (SpO2) measures oxygen saturation using Beer–Lambert law. The two wavelengths of light used are:
32. During laparoscopic surgery, intraperitoneal insufflation of CO2 causes a series of haemodynamic changes. Identify the correct sequence of events after peritoneal insufflation to 15 mmHg:
33. Invasive arterial blood pressure monitoring via radial artery cannulation is performed. The waveform shows pulsus paradoxus — systolic BP variation of >10 mmHg with respiration. In a ventilated patient, what does this indicate?