Is the STOP-BANG Predictive of Worsening OSA in the Early Postop Period in Patients Undergoing TJA?

Obstructive sleep apnea (OSA) is associated with increased morbidity and mortality after
total knee arthroplasty (TKA). Up to 30% of surgical patients have undiagnosed OSA; however,
many patients are unable to obtain a sleep study prior to surgery. In recent years the
STOP-BANG questionnaire (8 yes-no questions; ≥3 high-risk OSA) has become one of the most
common tools used in the preoperative period to identify patients at high-risk for OSA.
However, further research is needed to determine if the STOP-BANG is predictive of worsening
of sleep apnea parameters in patients undergoing TKA.

The purpose of this prospective observational cohort study is to determine in TKA patients
if the score on the STOP-BANG (<3, ≥3 to <5, or ≥5) is predictive of worsening sleep apnea
parameters (AHI, time with SPO2 <90% & 85% [T90 & T85], lowest oxygen saturation [LSAT], &
number of central apneas) during the first three days after surgery. The investigators
propose to enroll N = 168 patients undergoing TKA at NMCSD who are receiving multimodal
anesthesia/analgesia for surgery. Patients will complete a baseline unattended sleep study
prior to surgery then again for the first three days after surgery. Patients will be
categorized into three groups based on their STOP-BANG score (<3, ≥3 to <5, or ≥5) and the
investigators will first compare the groups to identify if there are differences between
baseline and postoperative sleep apnea parameters based on the STOP-BANG groups (<3, ≥3 to
<5, or ≥5). If differences are found the investigators will use multiple regression analysis
to determine if the STOP-BANG scores or categories and/or other covariates (i.e.,
comorbidity index, total morphine equivalents) are predictive of worsening sleep apnea
during the first three days after surgery.

Results of this study may help improve patient safety by allowing us to identify which group
of TKA patients with undiagnosed OSA may require more intensive postoperative monitoring and
therapy (i.e, ICU admission, need for continuous end-tidal CO2 monitoring, postoperative
positive airway pressure therapy) or change in the analgesic plan.

Inclusion Criteria:

- Age 18-90

- Scheduled for primary or revision TKA

- Able to read and understand the consent

- Able to complete an unattended OSA PM examination at home 1-60 days prior to surgery
and for three days postoperatively

Exclusion Criteria:

- Polysomnography confirmed OSA

- Significant comorbid medical conditions that may degrade the accuracy of PM (moderate
to severe pulmonary disease, neuromuscular disease, or congestive heart failure)