Continuous Pulse Oximetry Does Not Measure Blood Pressure
The evidence favoring improved outcomes from continuous electronic monitoring continues to dribble in, and the meta-analysis from Lam et al1 is to be commended for summarizing the evidence to date. The authors acknowledge that the prospective randomized trial of continuous pulse oximetry (CPOX) by Ochroch et al2 found that the CPOX significantly reduced intensive care unit (ICU) transfers due to pulmonary complications. Yet, they subsequently include nonpulmonary causes for ICU transfers in the study by Ochroch et al in their meta-analysis, and they conclude that there is only a trend toward reduced ICU transfer. Had they restricted their meta-analysis to pulmonary (respiratory) causes of ICU transfer, the relative risk of ICU transfer with CPOX would drop decisively from 0.81 to 0.32, with an upper 95% confidence interval of 0.69 vs 1.2 (Figure). When including the study by Taenzer et al,3 the relative risk would rise slightly to 0.46, but the 95% confidence interval would narrow to 0.31–0.67 (Figure). Although the causes of ICU transfers in the study by Taenzer et al are not described, it is less likely that the ICU transfers are as skewed by hemodynamic causes since the cohort was patients undergoing orthopedic, urologic, gynecologic, vascular, and general surgery, whereas Ochroch et al studied solely patients undergoing cardiothoracic surgery. There are approximately 45,000 acute respiratory compromise events on the ward in US hospitals per year, of which 40% result in death.4 A recent comprehensive review states that acute respiratory compromise is potentially avoidable with earlier recognition and recommends CPOX to be considered as a continuous monitor for patients at risk of all types of respiratory compromise.5 Institutions that recognize the urgent need to improve patient safety and outcomes have overcome barriers to CPOX adoption on the ward. The evidence to date provides not merely a trend but is conclusive that CPOX cuts the chances of an ICU transfer due to respiratory causes approximately in half.