Evaluation of changes in Modified Mallampati class in patients undergoing surgeries in prone position

Airway assessment and its appropriate management has always remained a crucial and a primary skill for an anaesthesiologist. The management constitutes various aspects such as airway assessments, grading, appropriate planning prior each surgical and effective execution of procedures to protect and maintain patency and ventilation.

 Airway related problems occur not only in the intraoperative period but also extends to postoperative period increasing mortality and morbidity during emergencies. Many at times these postoperative complications lead to re intubations, tracheostomy, prolonged hospital and ICU stay.

 Various positioning during surgical procedures like prone, left lateral, prolonged trendelenberg have been known to cause airway edema. The prone position, where in the patient lies face down is commonly used in spine surgeries and certain types of urological procedures can lead to potential compromise of the upper airway. Few other contributing factors causing airway edema are prolonged duration of surgery, excessive fluids and anaphylactic reactions.

The primary aim of the study is to evaluate the changes in Modified Mallampati class in patients undergoing surgeries in prone position.

There are many studies to predict difficult airway using various screening techniques preoperatively however there is a lack of research regarding the evaluation of airway changes that occur after prone position in major surgeries. Understanding these airway changes would enable anaesthesiologists to anticipate difficulties in airway management post extubation. This study will primarily focus on the changes in Modified Mallampati class at various intervals postoperatively in patients undergoing surgeries in prone position.

TEST PROCEDURE:

Before induction of anaesthesia, the Mallampati test will be assessed by using Samsoon and Young’s modification of Mallampati class. Mallampati test will be performed with the patients inclined to keep the head in a neutral position, fully open mouth, and tongue protruding out. To remove bias resulting from the position in the postoperative period arising due to pain, all the Modified Mallampati class evaluations during the preoperative and postoperative periods will be performed by raising the head end of the operation theatre (OT) table by 45° and keeping the examiner’s eye parallel to the patient’s mouth. This evaluation will be done at the interval of   2, 8, 24 hrs after surgery with preoperative assessment taken as baseline. Trained anaesthesiologists (minimum 2 years) will do the preoperative and postoperative assessments for airway changes. And on arrival in the OT, five lead electrocardiography, non‑invasive blood pressure (NIBP) and SpO2 attached. Induction of anaesthesia will be done with Inj. Propofol 2 mg per kg (iv), fentanyl 2 μg per kg (iv), and flexometallic tube of appropriate size will be used for tracheal intubation, facilitated by using 0.1 mg per kg(iv) vecuronium or 0.5 mg per kg(iv) atracurium. Thereafter 0.5–1% isoflurane with 60% nitrous oxide (N2O) in oxygen will be used to maintain anaesthesia with end‑tidal carbon dioxide pressure (ETCO2) kept in a range of 30–35 mm Hg. The intraoperative fluid replacement will be done with Ringer’s lactate.

Airway assessment will be done using the following parameter:

Modified Mallampati test: Patient will be assessed in seating position with examiner’s eyes at the level of patient’s mouth opening his/her mouth opened as widely as possible without phonation. On direct visualization patients will be classified as Modified Mallampati class 1, 2, 3 or 4. Class 1, 2 indicates easy intubation and Class 3,4 indicates difficult intubation.