Preoperative Evaluation MCQs

Stopping smoking is thought to be beneficial preoperatively, in order to minimize its acute adverse effects. Effects of carbon monoxide and nicotine are significantly reduced after 12-24 h abstinence; up to 6-8 weeks is thought to be necessary for restoration of ciliary and immunological activity. Reference: FRCA A TO Z, page no 530

The initial reduction in core temperature during general anesthesia is caused by redistribution of heat from the core to the periphery, which can be attenuated by increasing ambient temperature to minimize the gradient Reference: lippincott's anesthesia review chapter 14.

Explanation: ASA II: This classification is assigned to a patient with mild systemic disease . In this case, an uncomplicated pregnancy is considered a physiological state that alters the woman's baseline health but does not constitute a severe systemic disease. Pregnancy leads to changes such as increased cardiac output, altered respiratory mechanics, and changes in blood volume, which necessitate careful monitoring but generally does not increase the risk category beyond ASA II in the absence of other complications. Key Takeaways: ASA II reflects a healthy pregnan t patient with no significant comorbidities. Understanding the ASA classification helps assess the risk during anaesthesia and surgery. Reference : https://www.asahq.org/standards-and-practice-parameters/statement-on-asa-physical-status-classification-system

One metabolic equivalent is defined as the amount of oxygen consumed at rest, and is equal to 3.5 mL O2/kg/min. The energy cost of any activity can be determined by multiplying 3.5 to the oxygen consumption (mL O2/kg/min). METs can be assessed as follows: 1 MET-can take care of self (eating, dressing, toilet) 4 METs-can walk up a flight of steps or a hill 4 to 10 METs-can do heavy household work (scrubbing floors, lifting heavy furniture) >10 METs-can participate in strenuous sports (swimming, tennis, basketball, skiing) Reference: Lippincott's ANESTHESIA REVIEW: 1,001 QUESTIONS AND ANSWERS Paul Sikka, MD, PhD

Maximum voluntary ventilation (MVV) is a nonspecific pulmonary function test that measures the endurance of the ventilatory muscles and indirectly reflects the compliance of the lung and thorax as well as airway resistance. A decreased MVV may be caused by impairment to inspiration or expiration. In this patient, FEV1 is normal, which strongly suggests that the ventilatory impairment is during inspiration. A flow-volume loop would be a very useful confirmatory test. Reference: Barash: Clinical Anesthesia, ed 7, pp 1033-1034.

Mask ventilation, one of the most basic anesthesia techniques, can be challenging in some patients. Use of mask ventilation in patients who are prone to airway obstruction can be more difficult because of extra airway tissue (i.e., obese patients with a BMI >26), patients without teeth (i.e., tongue is closer to the roof of the mouth, and face conformity may not fit the mask well), and patients who snore (i.e., already have reason for airway obstruction). Mask ventilation can also be more difficult in patients who have a beard (i.e., harder to get a good mask seal), patients whose age is older than 55 years, patients with facial tumors, and patients with facial trauma. Use of an oral airway may be needed in many of these patients. Reference: Miller: Basics of Anesthesia, ed 6, p 227; Miller: Miller's Anesthesia, ed 8, p 1651.

Mask ventilation can be made difficult by anything that prevents the face mask from forming an adequate seal with the patient's face (e.g., a beard) or increases the resistance to airflow between the mouth and larynx. Edentulousness, a history of snoring, history of neck radiation, male gender, obesity, and Mallampati status ≥3 are all factors associated with difficult mask ventilation. Options a, b, and c represent risk factors for difficult intubation. In general, factors that make it difficult to align the oral axis with the laryngeal axis result in difficult intubation. Difficult mask ventilation can be remembered by BONES Beard Obesity No teeth Elderly Snorer Reference: Airway management by Rashid Khan 6th edition.

Although many books suggest that obesity is the most common cause of OSA, more recent data suggest that a large neck circumference (>44 cm) reflects pharyngeal fat deposition and is more strongly correlated with OSA than obesity (BMI >30). Other risk factors include male gender, middle age, evening alcohol consumption, or sleep-inducing medications. Reference: Hines: Stoelting's Anesthesia and Co-Existing Disease, ed 6, p 320; Miller: Miller's Anesthesia, ed 8, pp 2203-2204; Miller: Basics of Anesthesia, ed 6, pp 435-436.