A new study (re-posted below) found that more than 85% of bariatric patients who had pre-operative evaluation before bariatric surgery had significant obstructive sleep apnea. While the study was small (less than 400 patients), the findings of this study suggest two things:
1. An evaluation for sleep apnea should be part of routine pre-operative evaluation but ALSO –
given the very high rates of sleep apnea with increasing BMI – and the increased risks of heart attack, pulmonary hypertension and other serious, life-threatening consequences of untreated sleep apnea –
2. Increase screening for obstructive sleep apnea in ALL obese patients. (during routine evaluations, and as part of pre-operative evaluation before any surgery requiring general anesthesia.) [note: #2 is my personal recommendation – not the recommendation of the researchers presenting at this conference. But as you’ll note below – the preliminary screening questionaire can be done relatively easily, and given the value of findings – additional testing is reasonable even in patients with negative responses to the questionaire.
Due to the strong link between apnea and cardiac events – in our practice, we screened each patient using a series of questions to both the patient and the patient’s significant other (after obtaining patient permission).
To the patient: Do you snore? Have you ever been told you snore? Do you wake up tired, or feel sleepy during the day?
To significant other: Does the patient snore? Do you ever hear long pauses between breathing / snoring while the patient is sleeping? Do you ever think that he/she has stopped breathing?
(Then depending on circumstance, in-patient / out-patient – patients were informally screened using pulse oxymetry either in the cath lab or in the intensive care unit.) This means – we had nurses monitor the patients during sleep:
– Noting each and every time the patient’s oxygen saturation dropped below 92%
– Alterations in heart rate
– Presence of absence of apnea sleeping patterns, snoring etc.
Since our patients were already in the hospital under nursing care (in either the cath lab, or hospital room) the nurses were able to do this easily as part of routine assessment, and monitoring, and there was no extra cost to our patients.
In our case, this information was used for post-surgical management. After extubation, patients* were frequently placed on bipap for several hours to reduce atelectasis, and reintubation. In our at-risk patients, bipap was instituted as part of the sleep routine during their in-patient stay, with a pulmonary medicine referral, and evaluation for home CPAP therapy. In this way, we were able to avoid expensive/ and time-consuming tests prior to surgery, and still effectively treat our patients. to determine the predictive value of having a spouse tell us, “sometimes I can’t sleep because I am worried he won’t start breathing again” as we’ve heard on multiple occasions.
In our experience, the significant other was best able to provide important diagnostic information. Unfortunately, we haven’t recorded these findings as part of a research study
* this therapy was used independent of apnea status
Article Re-post: Presentation of a recent abstract at the American Society of Metabolic and Bariatric Surgery in Orlando, Florida
Sleep Test Needed Before Bariatric Surgery
-Charles Bankhead, reporter
ORLANDO — Most candidates for bariatric surgery have obstructive sleep apnea (OSA), making a case for polysomnography as a part of the preoperative evaluation of every patient, investigators concluded.
Of 359 patients who had preoperative polysomnography, 86% had positive tests, which showed severe OSA in half of the cases.
The patients had a high prevalence of the sleep disorder across the range of body mass index (BMI) values represented by the patient population, although every patient in the highest BMI category (≥60) tested positive for OSA, as reported here at the American Society of Metabolic and Bariatric Surgery meeting.
“Some people think that only patients in the highest BMI categories should be referred for polysomnography, because they are the patients who are most likely to have obstructive sleep apnea,” Abdul S. Bangura, MD, of Staten Island University Hospital in New York, told MedPage Today.
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Explain that most candidates for bariatric surgery have obstructive sleep apnea (OSA), making a case for polysomnography as a routine part of the preoperative evaluation of every patient.
- Note that every patient in the highest BMI category (≥60) had a polysomnographic test showing sleep apnea.
“However, our study showed a high prevalence of obstructive sleep apnea in all BMI categories. Because of that, we think polysomnography is justified during the preoperative evaluation of all bariatric surgery patients, and that is the policy at our institution.”
Obesity substantially increases the risk of OSA, and studies have documented a high prevalence of OSA and other sleep-related breathing disorders among patients evaluated for bariatric surgery. Polysomnography remains the gold standard for diagnosis and assessment of OSA, but practices vary with regard to use of the sleep test in the preoperative evaluation of candidates for weight-loss surgery, said Bangura.
Moreover, patients and physicians alike find sleep tests inconvenient, time-consuming, and expensive, he continued.
At his own center, polysomnography is a routine component of the preoperative workup. However, other centers have adopted a selective approach to use of the sleep test, relying on the level of clinical suspicion of OSA to guide decision making.
“Various scoring systems have been used to screen for sleep apnea, but all of them remain controversial,” said Bangura. “There is currently no standard protocol for screening obese patients for OSA.”
To see whether a routine or selective approach to preoperative testing for OSA is more appropriate, Bangura and colleagues retrospectively reviewed records of all patients who had bariatric surgery procedures at their center from 2005 to 2010. They identified 555 patients, including 359 (65%) who underwent polysomnographic evaluations during their preoperative workup.
Investigators used the apnea/hypopnea index (AHI) to categorize apnea severity, defining mild OSA as an AHI score of 5 to 15 events per hour; moderate as a score of 15 to 30; and severe as a score exceeding 30.
Of the 359 patients evaluated for OSA, 309 (86%) had positive tests, including some patients who had positive OSA tests prior to the preoperative evaluation for bariatric surgery. On the basis of AHI scores, 18% of the 359 patients had mild OSA, 17% had moderate OSA, and 51% had severe apnea.
Analysis of OSA prevalence by preoperative BMI showed that the following tested positive for OSA:
- 34 of 37 (92%) patients with BMI values of 35 to 39.9
- 178 of 218 (82%) of patients with BMI values of 40 to 49.9
- 78 of 85 (92%) of patients with BMI values of 50 to 59.9
- 100% of patients with BMI values of 60 or greater
“Based on these results, we consider routine polysomnography to be an essential part of the preoperative workup for all bariatric patients,” Bangura and colleagues concluded in their poster presentation.
Randomized controlled trials are required to provide evidence of guidelines on routine use of polysomnography as part of the workup for bariatric surgery patients, he said. Given the lack of a reliable prognostic system to predict OSA, the investigators urged consideration of routine polysomnography as part of the preoperative evaluation of all bariatric surgery candidates.