Accuracy of pulse oximeters in measuring oxygen saturation in patients with poor peripheral perfusion: a systematic review.

One of the most significant limitations of oximeters is their performance under poor perfusion conditions. This systematic review examines pulse oximeter model accuracy in adults under poor perfusion conditions. A multiple database search was conducted from inception to December 2020. The inclusion criteria were as follows: (1) adult participants (> 18 years) with explicitly stated conditions that cause poor peripheral perfusion (conditions localized at the oximeter placement site; or systemic conditions, including critical conditions such as hypothermia, hypotension, hypovolemia, and vasoconstricting agents use; or experimental conditions) (2) a comparison of arterial oxygen saturation and arterial blood gas values. A total of 22 studies were included and assessed for reliability and agreement using a modified Guidelines for Reporting Reliability and Agreement Studies tool. We calculated the accuracy root mean square error from bias and precision we extracted from the studies. Most oximeters (75%) were deemed accurate in patients with poor perfusion. Modern oximeters utilizing more complex algorithms were more likely to be accurate than older models. Earlobe placement of oximeters seemed more sensitive, with greater measurement accuracy, than on fingertip placement. Only one study controlled for skin pigmentation, and none strictly followed Food and Drug Association recommendations for experiments to determine oximeter accuracy. Oximeters are accurate in poorly perfused patients, especially newer oximeter models and those placed on earlobes. Further studies are needed that examine multiple oximeter models used on a diverse selection of patients while following FDA recommendations to examine oximeter accuracy.

The effectiveness of positive airway pressure therapy in reducing postoperative adverse outcomes in surgical patients with obstructive sleep apnea: A systematic review and meta-analysis.

IMPORTANCE: Obstructive sleep apnea (OSA) is prevalent in surgical patients and is associated with an increased risk of adverse perioperative events. STUDY OBJECTIVE: To determine the effectiveness of positive airway pressure (PAP) therapy in reducing the risk of postoperative complications in patients with OSA undergoing surgery. DESIGN: Systematic review and meta-analysis searching Medline and other databases from inception to October 17, 2021. The search terms included: "positive airway pressure," "surgery," "post-operative," and "obstructive sleep apnea." The inclusion criteria were: 1) adult patients with OSA undergoing surgery; (2) patients using preoperative and/or postoperative PAP; (3) at least one postoperative outcome reported; (4) control group (patients with OSA undergoing surgery without preoperative and/or postoperative PAP therapy); and (5) English language articles. PATIENTS: Twenty-seven studies included 30,514 OSA patients undergoing non-cardiac surgery and 837 OSA patients undergoing cardiac surgery. INTERVENTION: PAP therapy MAIN RESULTS: In patients with OSA undergoing non-cardiac surgery, PAP therapy was associated with a decreased risk of postoperative respiratory complications (2.3% vs 3.6%; RR: 0.72, 95% CI: 0.51-1.00, asymptotic P = 0.05) and unplanned ICU admission (0.12% vs 4.1%; RR: 0.44, 95% CI: 0.19-0.99, asymptotic P = 0.05). No significant differences were found for all-cause complications (11.6% vs 14.4%; RR: 0.89, 95% CI: 0.74-1.06, P = 0.18), postoperative cardiac and neurological complications, in-hospital length of stay, and in-hospital mortality between the two groups. In patients with OSA undergoing cardiac surgery, PAP therapy was associated with decreased postoperative cardiac complications (33.7% vs 50%; RR: 0.63, 95% CI: 0.51-0.77, P < 0.0001), and postoperative atrial fibrillation (40.1% vs 66.7%; RR: 0.59, 95% CI 0.45-0.77, P < 0.0001). CONCLUSION: In patients with OSA undergoing non-cardiac surgery, PAP therapy was associated with a 28% reduction in the risk of postoperative respiratory complications and 56% reduction in unplanned ICU admission. In patients with OSA undergoing cardiac surgery, PAP therapy decreased the risk of postoperative cardiac complications and atrial fibrillation by 37% and 41%, respectively.