BOSTN Screening for Obstructive Sleep Apnea: Can a simple screening tool improve outcomes?

One in four patients undergoing surgery suffers from obstructive sleep apnea (OSA), a sleep disorder resulting in intermittent breathing pauses throughout the night. Affected patients have a higher risk of cardiovascular and respiratory problems after surgery, are admitted to intensive care units more often and stay in hospital longer.

Obstructive Sleep ApneaIn 2006, the Joint Commission recommended that hospitals implement strategies to identify patients at increased risk of OSA in order to prevent postoperative complications. At BIDMC, a team of doctors, nurses and respiratory therapists developed management guidelines for these patients under the leadership of Eswar Sundar, MD (Director of Clinical Operations, Department of Anesthesia, Critical care and Pain Medicine). The result was a perioperative care bundle, of which the BOSTN screening score was an integral part.

“We developed a simple screening tool that can quickly be applied by nurses to every patient in the perioperative holding area,” explains Dr. Sundar. The BOSTN score was implemented into routine clinical use in May 2008 and assigns a point for each of the following preexisting conditions:

  • Body mass index ≥ 30 kg/m2,
  • Observed breathing pauses (apneas),
  • Loud Snoring,
  • Daytime Tiredness, and
  • Neck circumference ≥16.5 inches in women or ≥17.5 inches in men.

All of these predictors are common risk factors of sleep apnea: In OSA, muscles of the throat relax during sleep and block the airway. This most commonly results in loud snoring. When oxygen levels in the blood drop because of the obstructed airway, the brain senses this and initiates arousal, which commonly results in gasping for air. The constant awakenings throughout the night interrupt normal sleep and cause daytime sleepiness in affected patients. These symptoms are worse in overweight patients with large neck circumferences, as the additional fat around the neck makes it easier for the airway to collapse at night.

“What sets our screening tool apart from others is its integration into electronic medical records and the routine application as part of the perioperative workflow,” continues Dr. Sundar. “If a patient has a high risk, a flag appears onscreen and alerts the anesthesiologist, who can then adjust the care provided based on the guidelines for the management of patients with OSA.”

The introduction of BOSTN also provided a unique opportunity for research. During the decade following the implementation of BOSTN, various data points were retrieved from electronic medical record of patients undergoing surgery at BIDMC. In collaboration with Dr. Sundar, a group of researchers led by Matthias Eikermann, MD PhD (Vice Chair of Faculty Affairs, Department of Anesthesia, Critical care and Pain Medicine) collected data from over 200,000 surgical cases and analyzed whether a high BOSTN score was associated with adverse outcomes. “We hypothesized that patients with a high score would experience respiratory problems after surgery more often,” explains Dr. Eikermann. The findings of this study were recently published in the July 2019 issue of Anesthesia & Analgesia.

Surprisingly, patients with high BOSTN scores were more likely to experience better outcomes. Peter Santer, MD, a research fellow and co-first author on the research study elaborates: “While patients screened as high-risk using BOSTN showed lower oxygen levels immediately after surgery, they required less mechanical ventilation within the first week after surgery, were in hospital for shorter periods of time, were readmitted less frequently and even showed lower mortality rates. We speculate that the implementation of this patient care bundle led to higher awareness of OSA among clinicians and may have influenced their intraoperative decision-making.”

“This publication is the culmination of collaborative efforts across many levels of our Department,” says Dr. Eikermann. “It highlights the importance of BOSTN for patient care, but also exemplifies how good teamwork between clinical operations and research can lead to successful results. The data collected as part of this research has formed an important foundation for other retrospective analyses and continues to be used in a variety of different research projects.”


Raub D, Santer P, Nabel S, Platzbecker K, Munoz-Acuna R, Xu X, Friedrich S, Ramachandran SK, Eikermann ME, Sundar E. BOSTN bundle intervention for perioperative screening and management of patients with suspected obstructive sleep apnea: a hospital registry study. Anesth Analg. 2019; doi:10.1213/ANE.0000000000004294