Airway Changes in Patients Undergoing Elective Surgical Procedures in the Prone and Trendelenburg Positions

Assessing Intraoperative Airway Changes and Their Regression to Baseline in Patients Undergoing Elective Surgical Procedures in the Prone and Trendelenburg Positions

The goal of this study is to track the intraoperative changes that occur in the airways of patients undergoing 1) laparoscopic surgeries in the Trendelenburg position, and 2) spinal surgeries in the prone position, as well as the regression of these changes postoperatively. These surgeries are known to cause edema and swelling of the soft tissues of the head and neck, temporarily worsening airway anatomy, but there is little data quantifying these changes, and no studies have investigated the time course required for the airway to return to its baseline after extubation. This would be important clinical information given that airway management is always a major concern perioperatively. The investigators will test hypotheses by evaluating patients' airways preoperatively, immediately post-extubation, and at regular intervals thereafter using the Modified Mallampati Score class (MMS), in which a patient's airway is scored from class 1 to 4 (in which 4 indicates the highest likelihood of a difficult intubation) based on the visibility of the soft palate, uvula, and faucial pillars inside the oral cavity.

Study Overview

• Status: Active, not recruiting
• Conditions: Airway Management
• Intervention / Treatment: Other: Intubation

Detailed Description

Background: One of the primary methods to assess airway dimension changes is the Modified Mallampati Score (MMS). MMS has been a valuable tool in assessing difficulty of intubation in previous studies as it is a simple, reproducible, and reliable preoperative and preanesthetic assessment of oral volume. MMS is evaluated by asking the patient to open their mouth and protrude their tongue without phonation. A score on a scale of 1-4 is assigned based on identifiable intraoral anatomic structures. MMS scores of 3 and 4 are strongly associated with difficult laryngoscopy and intubation.

Extensive observational research in the obstetric population has demonstrated that airway changes, including increasing MMS and decreasing oropharyngeal volume, occur during labor. It has been found that 63% of parturients experienced an increase in MMS over the course of their labor, with the fraction of patients scoring 3 or 4 peaking at 51.7%, compared with only 10.3% early in labor. Notably, of those patients that reached a class 4, 21% remained at that classification 48 hours postpartum. It has been found that 18% of patients whose airway class worsened during labor had not returned to their prelabor class 36-48 hours after delivery.

These obstetric findings have prompted a limited number of studies investigating airway changes in patients undergoing surgical procedures. This study will focus on surgeries in the prone and Trendelenburg positions, as they would intuitively predispose patients to edema and fluid retention in the head and neck. MMS increased in 78% of patients, with 29% increasing by two or more classes in patients undergoing lumbar spine surgery in the prone position. Furthermore, although laparoscopic surgery has been shown to increase lung and chest wall mechanical impedance, which leads to increases in abdominal and intrathoracic pressure, as well as an increase in central venous pressure with subsequent increases in intraocular pressure, no studies have been performed to specifically track resultant airway changes. Lastly, to investigators' knowledge no studies have investigated the postoperative resolution of airway changes after either type of procedure.

Rationale: There is evidence, both investigational and anecdotal, that airway changes may occur during certain surgeries or procedures, and that patient positioning may play a large role in precipitating them. However, research on this phenomenon in the surgical population, unlike the obstetric population, is sparse. Similarly, investigations into the time required for airway changes to regress back to baseline has been included in a number of obstetric airway studies, but not in any surgical ones. Lastly, it has been suggested that other surgical factors, such as fluid balance or procedure duration, may alter the degree of airway changes, but results from the few recent studies on the topic have been unclear. Thus, this study seeks to further investigate the influence of prone and Trendelenburg positioning, as well as surgical variables, on perioperative airway changes, and quantify the time required for patients' airways to return to their preoperative state.

Based on clinical observation, the primary hypothesis is that there will be a significant difference between mean scoring class change between 2 study groups from preoperative baseline to initial postoperative assessment. Investigators hypothesize that T-burg surgery patients will have a mean change of 2 classes compared to a mean change of only one class for prone spine surgery patients.

The secondary hypothesis is that airway changes occurring in patients undergoing prone procedures will resolve significantly sooner than (3 - 4 hours) than those of patients undergoing Trendelenburg surgeries (> 4 hours).

Thirdly investigators will investigate the effects of demographic, physiological, and surgical & anesthetic variables on postoperative MMS changes and their resolution.

• Study Type: Observational
• Enrollment (Estimated): 180

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02111
      • Tufts Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

All patients over the age of 18 undergoing scheduled spinal surgery in the prone position or laparoscopic or surgery in the Trendelenburg position.

Description

Inclusion Criteria:

• All patients scheduled for elective spinal surgery in the prone position or laparoscopic or surgery in the Trendelenburg position.

Exclusion Criteria:

• Patients with a preoperative MMS of 4, existing oropharyngeal pathology, or the inability to fully open their mouth, or severely limited neck mobility

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in MMS after surgery	Based on institutional observations, we expect both prone and Trendelenburg patients to exhibit significant airway changes/increases in MMS after surgery. Additionally, we expect to find that these changes will require approximately 4 hours to fully regress, and that perioperative and intraoperative factors, such as IV fluid and steroid administration, will affect both the degree of airway changes and the time course of their regression.	1-4 hours after surgery

Collaborators and Investigators

• Sponsor: Tufts Medical Center

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2015
• Primary Completion (Estimated): December 31, 2025
• Study Completion (Estimated): July 31, 2026

Study Registration Dates

• First Submitted: April 11, 2016
• First Submitted That Met QC Criteria: April 13, 2016
• First Posted (Estimated): April 14, 2016

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: February 25, 2025
• Last Verified: February 1, 2025

More Information

Terms related to this study

• Keywords: prone position; airway; Trendelenburg position; MMS; airway changes
• Other Study ID Numbers: IRB 11705

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO