SEE Question

Your next patient is scheduled for laparoscopic abdominal hysterectomy. She recalls having a severe sore throat after her last surgery and asks if there is any way to prevent it this time. According to a recent study evaluating the use of smaller diameter tracheal tubes for the prevention of postoperative sore throat, which of the following outcomes is MOST likely if you use a 6.0-mm inner diameter tracheal tube instead of a 7.0-mm inner diameter tube in this patient?

• □ (A) Lower likelihood of sore throat at one hour after surgery
• □ (B) Similar likelihood of sore throat at 24 hours after surgery
• □ (C) Higher peak inspiratory pressures during surgery

Postoperative sore throat can impair recovery after surgery and is distressing to patients. Although smaller diameter tracheal tubes may decrease the rate or severity of postoperative sore throat, they increase resistance to airflow and may thus increase ventilation pressures and potentially impair ventilation.

A recent randomized clinical trial evaluated the effects of smaller tracheal tubes on postoperative sore throat and ventilation variables using lower tidal volumes to limit airway pressures. Adult patients undergoing laparoscopic lower abdominal surgery were randomized to receive either a larger diameter tracheal tube (7.5-mm inner diameter for men, 7.0-mm inner diameter for women; n = 88) or smaller diameter tracheal tube (6.5-mm inner diameter for men, 6.0-mm inner diameter for women; n = 84). The exclusion criteria included patients with a body mass index (BMI) greater than 35 kg/m² and surgery in the steep Trendelenburg position. Intraoperative management was standardized, with tracheal tube cuff pressures maintained at 15 to 25 mm Hg. All patients received 40% oxygen and mechanical ventilation with a tidal volume of 6 to 8 mL/kg predicted body weight, inspiratory-to-expiratory ratio of 1:2, and positive end-expiratory pressure of 5 cm H₂O. End-tidal carbon dioxide (ETCO₂) was maintained at 4.6 to 6.0 kPa (35-45 mm Hg) by adjusting the respiratory rate.

The primary outcome of the study was the rate and severity of sore throat at one hour after surgery. Other outcomes included the rate and severity of sore throat at 24 hours after surgery; the rate and severity of hoarseness at one and 24 hours after surgery; and several intraoperative ventilatory variables, including plateau airway pressure, peak inspiratory pressure, and ETCO₂. Postoperative sore throat and hoarseness were graded as none, mild, moderate, or severe and assessed by an investigator blinded to the group assignment.

The overall rate of postoperative sore throat (mild, moderate, or severe) was lower with smaller diameter tracheal tubes than with larger diameter tubes at one hour after surgery (6.0% vs. 31.8%). The overall rate of postoperative sore throat was also lower with smaller diameter tracheal tubes than with larger diameter tubes at 24 hours after surgery (11.9% vs. 27.3%). As shown in the Table, the severity of throat pain was less with smaller diameter tracheal tubes at both one and 24 hours postoperatively.

The overall rate of postoperative hoarseness (mild, moderate, or severe) was lower with smaller diameter tracheal tubes than with larger diameter tubes at both one hour and 24 hours after surgery (25.0% vs. 47.7% at one hour; 10.7% vs. 34.1% at 24 hours). The severity of hoarseness was also less with smaller tracheal tubes at both time points. No differences in any intraoperative ventilation variables were observed between groups, including peak inspiratory pressure, plateau airway pressure, or ETCO₂.

In summary, in adults undergoing lower abdominal laparoscopic surgery, smaller diameter tracheal tubes were associated with reduced rate and severity of sore throat and hoarseness after surgery, with no apparent adverse effects on ventilatory mechanics.