Lateral positioning reduced the incidence of hypoxaemia in sedated adult patients compared with supine positioning in a multicenter randomized trial. Among 2,143 patients in the postanesthesia care unit, hypoxaemia occurred in 5% of patients in the lateral group vs 15% in the supine group. Severe hypoxaemia occurred in less than 1% of patients who were placed laterally and 5% of those placed supine. Zero patients in the lateral group experienced oxygen saturation below 80% and 70%, compared with 9 and 3 patients respectively in the supine group. The mean decrease of oxygen saturation from baseline was 2% in the lateral group and 3.2% in the supine group, while a decrease in oxygen saturation of more than 3% occurred in 230 patients (21%) in the lateral group and 317 patients (30%) in the supine group, wrote Hui Ye, MD, of Zhejiang University School of Medicine in China, with colleagues. They noted that the number needed to treat to prevent one case of hypoxaemia was 11.
Airway rescue interventions were also less frequent in the lateral group: they occurred in 6% of patients compared with 14% in the supine group, and the number needed to treat for preventing airway interventions was 15. No patients required insertion of an oropharyngeal or nasopharyngeal airway or reintubation. The mean lowest oxygen saturation was 97% in the lateral group and 96% in the supine group. Postanesthesia care unit (PACU) stay was shorter with lateral positioning, averaging 38 minutes compared with 41 minutes with supine positioning. Tachycardia was also less frequent in the lateral group—7% vs 10%—while bradycardia, hypotension, arrhythmias, nausea or vomiting, and aspiration events did not differ significantly between the two groups.
The trial enrolled adult patients who underwent surgery with general anesthesia and were sedated following extubation. One minute following extubation, patients with Ramsay sedation scores of 2 to 4 were randomized to lateral or supine positioning. Patients in the lateral group were placed on their side, while those in the supine group were positioned flat without head elevation. All patients received oxygen at 2 liters per minute by nasal cannula. Outcomes were observed for 10 minutes following positioning.
The mean age of participants was 53 years, 54% were women, and the mean body mass index was 24. Surgical procedures included abdominal, orthopedic, gynecologic, otorhinolaryngologic, and respiratory operations. Subgroup analyses showed consistent benefits of lateral positioning across age, body mass index, and procedure type. A sex-related interaction was observed: lateral positioning had a stronger effect in men, though it remained beneficial in both sexes. A notable finding was the absence of clear benefit among current smokers. In addition, patients with lower Mallampati scores (1 or 2) benefited significantly more than those with higher scores (3 or 4). The researchers explained that higher Mallampati scores reflect multilevel obstruction patterns that are less responsive to simple positional adjustments, whereas lower scores are associated with tongue base obstruction, which is more readily alleviated by lateral positioning.
The incidence of hypoxaemia in this trial was higher than projected, the authors noted. They wrote, “This discrepancy is likely explained by the broader range of surgical patients and risk factors included in our study. We enrolled patients undergoing high risk procedures that are known independent contributors to respiratory complications—notably thoracic, lung, and major abdominal surgeries, as well as emergency procedures. In contrast, the literature informing our power calculation mostly examined elective, lower risk populations (excluding thoracic surgery, otorhinolaryngological surgery, and patients with difficult airways). As a result, the inclusion of higher risk surgeries and patients in our trial increased the overall incidence of hypoxaemia compared with previous reports. Importantly, despite the higher baseline risk, lateral positioning consistently showed benefit."
The study had several limitations. The observation period was restricted to the first 10 minutes following extubation, and later hypoxaemic events were not assessed. The open-label design may have introduced bias because staff were aware of group assignments. The study population was younger and had lower body mass index than patients commonly seen in Western settings, which may limit generalizability. A semirecumbent position was not evaluated.
The researchers concluded that lateral positioning reduced both the incidence and severity of hypoxaemia and decreased the need for airway rescue interventions among sedated adult patients recovering from general anesthesia in the PACU. They noted that lateral positioning is a simple, low-cost intervention that requires no specialized equipment and is feasible even in resource-limited settings, and could reduce cardiac stress or unplanned intensive care admissions downstream.
Full disclosures can be found in the study.
Source: The BMJ