Sensitivity to remifentanil and its predictive factor in male patients with moderate to severe obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is associated with increased risk of postoperative complications, which is possibly related to increased sensitivity to opioid. However, the effect of increased sensitivity to opioids in patients with OSAS remains controversial. This study aims to investigate whether male patients with moderate to severe OSAS have increased sensitivity to opioid remifentanil and its related predictive factors, so as to provide a reference for the rational use of opioids in patients with OSAS.

This study was a prospective study. From December 28, 2021 to October 15, 2022, a total of 61 male patients aged 22 to 60 years old, American Society of Anesthesiologists (ASA) status I and II, who underwent nasopharyngeal surgery under general anesthesia, were selected. According to STOP-BANG questionnaire score and apnea-hypopnea index (AHI), the patients were divided into an OSAS group (n=39) and a control group (n=22). The pupil diameter (PD) of the patients was measured by hand-held monocular pupillometer, and the perception threshold (PT) and pain tolerance threshold (PTT) of the patients were measured by somatosensory evoked potential stimulator. The initial PD, PT, and PTT were measured in a quiet environment and recorded as PD0, PT0, and PTT0. Changes in PD, PT, PTT, respiration, and consciousness were recorded after remifentanil infusion. Age, body mass index (BMI), smoking, AHI, minimal oxygen saturation, and percentage of sleep time spent with oxygen saturation <90% (T90) were included as independent variables in multiple linear regression equations to analyze the possible predictors of increased opioid sensitivity in patients with moderate to severe OSAS.

There were no significant differences in PD0, PT0 and PTT0 between the OSAS group and the control group (all P>0.05). After remifentanil infusion, there was no significant difference in the rate of PT change between the 2 groups (P>0.05). The change rate of PTT and PD in the OSAS group was significantly higher than that in the control group (P<0.05 and P<0.001, respectively), PD in the OSAS group was significantly lower than that in the control group (P<0.001). During remifentanil infusion, there were no significant differences in the incidence of respiratory depression and the distribution of observer's assessment of alertness/sedation (OAA/S) scores between the 2 groups (both P>0.05), and there were no changes in mental status and airway support in the patients of the 2 groups. Multiple linear regression showed that T90 was positively correlated with miosis rate (β=0.597, 95% CI 0.269 to 0.924, P<0.05) and the rate of PTT change (β=0.458, 95% CI 0.116 to 0.800, P<0.05). However, minimal oxygen saturation, age, BMI, smoking, and AHI were not correlated with PD change rate and PTT change rate in the OSAS patients (all P>0.05).

Male patients with moderate to severe OSAS have increased sensitivity to remifentanil, the duration of nocturnal desaturation may be its predictive factor. Male patients with moderate to severe OSAS with a longer duration of nocturnal hypoxia are more sensitive to remifentanil, and the use of opioids in these patients should be more cautious in clinical.