Most of our focus on obstructive sleep apnea (OSA) in the hospitalized patient has focused on the perioperative period (see list of prior columns below). But OSA prevalence is also high in patients admitted to medical (non-surgical) units. In our July 2010 Patient Safety Tip of the Week Obstructive Sleep Apnea in the General Inpatient Population we noted that screening with the STOP and Berlin questionnaires found a potential 60% prevalence of obstructive sleep apnea in patients admitted to general medicine units in an urban academic hospital, most of whom had never been diagnosed with OSA. Many of the patients were obese and most had comorbidities. A high percentage of these patients received intravenous narcotics or were prescribed benzodiazepines or both and none of these received any supplemental respiratory monitoring. The study highlights the risk of using such medications in potentially high risk patients and also highlights the potential benefits of using simple tools like STOP in identifying potential OSA candidates.
In our prior columns weve also discussed the relative paucity of evidence for use of CPAP in hospitalized patients deemed at high risk for OSA by screening.
Now a new study addresses both issues. Sharma and colleagues (Sharma 2016) used the STOP tool to screen obese patients (BMI ≥ 30 kg/m2) admitted to select medical (non-surgical) services and sorted them into high- and low-risk for OSA groups. They found that rapid response system (RRS) activations were significantly more frequent in those patients in the high-risk group. Moreover, high-risk patients who were put on PAP (CPAP, BiPAP, or APAP) and were compliant with PAP were significantly less likely to have RRS activations than those high-risk patients not compliant with PAP or not receiving PAP.
They screened over 2500 inpatients over a 15-month period and found that 76% were at high risk for OSA (Yes answer to 2 or more of the 4 questions in STOP). Admitting teams were notified when a high risk designation was made and whether to get a Pulmonary/Sleep Medicine consultation was left up to the admitting team. Slightly less than half the high-risk group received such consultations. Note that patients with known OSA were excluded from the analysis. Of those who received consultations, PAP (usually CPAP but BiPAP or APAP for some) was recommended for almost three quarters. Almost 70% of the latter were deemed compliant with PAP (based on at least 4 hours PAP use during sleep noted by respiratory therapists).
The RRS activation rate per 1000 admissions was 43.6 for patients at high risk for OSA vs. 25.9 in low-risk patients. For PAP-compliant patients the RRS activation rate per 1000 admissions was 16.99 vs. 53.4 in PAP non-compliant patients. In addition, mean hospital LOS (length of stay) was significantly higher in the high risk group (7.52 vs. 6.98 days). The study implies (but does not actually include the data) that those patients compliant with PAP had lower mean LOS.
The study was an observational study and because it was not randomized there may have been biases or confounding factors that affected the decision to use PAP. As the authors appropriately note, it is also not surprising that patients at high risk for OSA would have longer LOS since they also likely have more comorbidities.
But this study certainly lays the foundation for larger randomized controlled studies. While it would have been useful to have data on other outcomes, the beneficial effect of PAP on reducing RRS activations and LOS would seem to justify further study not only for patient safety concerns but also potentially for the bottom line of hospitals.
Weve always strongly advocated screening pre-op patients for OSA risk with the STOP-Bang tool. This study would suggest we might extend such screening to all inpatients who have at least a high BMI. We already recommend any hospital inpatient who will be receiving opioids be screened with the STOP-Bang questionnaire. Though we recommend universal use of capnography for inpatients on opioids, those hospitals with limited resources should at least be using capnography or otherwise monitoring for apnea in patients at high risk for OSA who are receiving opioids. The current study is also another one on the pro- side for using PAP in hospitalized patients deemed at high risk for OSA, though further definitive research is needed.
Our prior columns on obstructive sleep apnea in the perioperative period:
June 10, 2008 Monitoring the Postoperative COPD Patient
August 18, 2009
August 17, 2010
July 13, 2010 Postoperative Opioid-Induced Respiratory Depression
November 2010 More on Preoperative Screening for Obstructive Sleep Apnea
February 22, 2011 Rethinking Alarms
November 22, 2011 Perioperative Management of Sleep Apnea Disappointing
May 22, 2012 Update on Preoperative Screening for Sleep Apnea
February 12, 2013 CDPH: Lessons Learned from PCA Incident
February 19, 2013 Practical Postoperative Pain Management
March 26, 2013 Failure to Recognize Sleep Apnea Before Surgery
September 24, 2013 Perioperative Use of CPAP in OSA
May 13, 2014 Perioperative Sleep Apnea: Human and Financial Impact
March 3, 2015 Factors Related to Postoperative Respiratory Depression
August 18, 2015 Missing Obstructive Sleep Apnea
Sharma S, Chowdhury A, Tang L, et al. Hospitalized Patients at High Risk for Obstructive Sleep Apnea Have More Rapid Response System Events and Intervention Is Associated with Reduced Events. PLOS One 2016; Published: May 11, 2016