# Pulse Oximetry Desaturation in the Postoperative Recovery Room in Patients with Obesity and Diabetes Using GLP-1 Agonists: A Retrospective Observational Study

## TL;DR

This study examines how GLP-1 agonists, obesity, and diabetes affect postoperative oxygen levels and glucose in patients undergoing urologic surgery.

## Contribution

The study identifies a link between morbid obesity and greater postoperative oxygen desaturation in diabetic patients using GLP-1 agonists.

## Key findings

- Patients with morbid obesity had significantly higher DSpO2 compared to those without morbid obesity (p=0.0254).
- There was a trend toward higher incidence of DSpO2 > 4% in patients with morbid obesity (24%, p=0.14).
- No significant association was found between GLP-1-hold duration and DSpO2 or fasting glucose.

## Abstract

Background and objectives: Glucagon-like peptide-1 agonists (GLP-1), obesity, and diabetes may delay gastric emptying in some settings. We tested three hypotheses. First, the duration of GLP1-hold is associated with a larger difference between pulse oximetry at room air immediately preoperatively and one hour postoperatively, just prior to discharge home (DSpO2), as a marker of clinically important atelectasis and/or micro-aspiration. Second, we tested the hypothesis that the duration of GLP1-hold affects fasting glucose. Third, we tested the hypothesis that DSpO2 is linked to morbid obesity.

Materials and methods: In this retrospective observational cohort study, we screened the cohort of all 1571 patients undergoing urologic ambulatory surgery in one stand-alone center between September 2023 and September 2024. The inclusion criteria were diabetics using GLP-1 within 30 days, creatinine below 2 mg/dL, and age between 18 and 80 years. The outcomes of fasting glucose and DSpO2 were compared between the groups holding GLP-1 longer and shorter than seven days. The outcome DSpO2 was also compared between the groups with and without morbid obesity, defined generally as a body mass index (BMI) of over 35 kg/m² in the presence of one major comorbidity. All of our study subjects had diabetes mellitus, a major comorbidity.

Results: Among all 107 subjects, 56% had laryngeal mask airways and 9% endotracheal tubes. GLP-1 was held 12 ± 8 days (mean ± SD). DSpO2 was 1.5% ± 1.9 with short GLP-1-hold versus 1.8% ± 2.0 with long GLP-1-hold (p=0.41). The mean glucose was 130 mg/dL ± 49 with short GLP1-hold versus 138 mg/dL ± 39 with long GLP-1-hold (p=0.69). DSpO2 was 2.29% ± 1.78 with morbid obesity (N=38) versus 1.43% ± 1.99 without (N=69, p=0.0254, unpaired two-tailed t-test). Patients with morbid obesity showed a trend toward twice the incidence (at 24%) for DSpO2 > 4% (chi-square, p=0.14).

Conclusions: It may be prudent to protect the airway with endotracheal intubation for patients with morbid obesity and diabetes using GLP-1, especially in the lithotomy position.