Eric Deflandre

Development and validation of a morphologic obstructive sleep apnea prediction score: The DES-OSA score

BACKGROUND:Obstructive sleep apnea (OSA) is a common and underdiagnosed entity that favors perioperative morbidity. Several anatomical characteristics predispose to OSA. We developed a new clinical score that would detect OSA based on the patient’s morphologic characteristics only. METHODS:Patients (n = 149) scheduled for an overnight polysomnography were included. Their morphologic metrics were compared, and combinations of them were tested for their ability to predict at least mild, moderate-to-severe, or severe OSA, as defined by an apnea–hypopnea index (AHI) >5, >15, or >30 events/h. This ability was calculated using Cohen &kgr; coefficient and prediction probability. RESULTS:The score with best prediction abilities (DES-OSA score) considered 5 variables: Mallampati score, distance between the thyroid and the chin, body mass index, neck circumference, and sex. Those variables were weighted by 1, 2, or 3 points. DES-OSA score >5, 6, and 7 were associated with increased probability of an AHI >5, >15, or >30 events/h, respectively, and those thresholds had the best Cohen &kgr; coefficient, sensitivities, and specificities. Receiver operating characteristic curve analysis revealed that the area under the curve was 0.832 (95% confidence interval [CI], 0.762–0.902), 0.805 (95% CI, 0.734–0.876), and 0.834 (95% CI, 0.757–0.911) for DES-OSA at predicting an AHI >5, >15, and >30 events/h, respectively. With the aforementioned thresholds, corresponding sensitivities (95% CI) were 82.7% (74.5–88.7), 77.1% (66.9–84.9), and 75% (61.0–85.1), and specificities (95% CI) were 72.4% (54.0–85.4), 73.2% (60.3–83.1), and 76.9% (67.2–84.4). Validation of DES-OSA performance in an independent sample yielded highly similar results. CONCLUSIONS:DES-OSA is a simple score for detecting OSA patients. Its originality relies on its morphologic nature. Derived from a European population, it may prove useful in a preoperative setting, but it has still to be compared with other screening tools in a general surgical population and in other ethnic groups.

Obstructive Sleep Apnea and Smoking as a Risk Factor for Venous Thromboembolism Events: Review of the Literature on the Common Pathophysiological Mechanisms

Venous thromboembolism events (VTE) are a common and preventable cause of postoperative complications. Interestingly, smoking and obstructive sleep apnea syndrome (OSA) affecting a large part of our population (and especially obese patients) are two underestimated predisposing factors of VTE. Many coagulation disorders favoring thromboembolism have been identified in the case of OSA and smoking and are reviewed in this article. They can be divided into two entities: endothelial dysfunction and hemostasis disorders. Interestingly OSA and smoking share common pathways to the prothrombotic state. The interactions with others comorbidities will also be discussed. This article provides pathophysiological mechanisms of the increased risk of thromboembolism in OSA patients and smokers, which should help manage these patients more adequately during the perioperative period.

What mediates postoperative risk in obstructive sleep apnea: airway obstruction, nocturnal hypoxia, or both?

To the Editor, Obstructive sleep apnea (OSA) is known to be an independent risk factor for postoperative complications. The apnea–hypopnea index (AHI) – i.e., the number of apnea and hypopnea events per hour of sleep during overnight polysomnographic (PSG) monitoring – has typically served to classify the severity of OSA (with severe OSA defined by an AHI[30). A recently reported matched cohort study by Mutter et al. that measured the severity of OSA by AHI during PSG monitoring appears to constitute a landmark for identifying OSA patients at risk of postoperative complications. In that study, increased severity of OSA was associated with increased risk of complications, although only the data for the severe OSA group reached statistical significance. Hypoxic events in OSA patients may have significant pathophysiological consequences. Although confirmatory prospective studies are lacking, we hypothesize that these hypoxia-mediated inflammatory modifications could increase the risk of postoperative complications, acting cumulatively with the AHI or even mediating its effects entirely. An oxygen desaturation index (ODI) can also be derived from the PSG analysis and can be used as an independent measure of hypoxia. The ODI represents the number of times per hour that the capillary blood oxygen saturation drops by C4% from baseline during overnight PSG monitoring. We recently reported the results of a study (EudraCT: 2006-006558-92) that outlined the development of the DES-OSA score (the DES part of the acronym being derived from the initials of the investigators involved in its development) in 139 patients. The Figure shows the relation between the ODI and the AHI from that study. Clearly, some, but not all, patients with severe OSA (AHI [ 30) experienced nocturnal hypoxia. In the patients with severe OSA and hypoxia, the ODI varied considerably, with minimum and maximum values of 2 and 92 events per hour, respectively, although the median [interquartile range] was only 25 [10–37] events per hour. Among patients with severe OSA, 33% encountered no (ODI \ 5 events per hour) or mild (ODI 5–15) nocturnal hypoxia; 29% had moderate nocturnal hypoxia (ODI 15–30); and 38% had severe nocturnal hypoxia (ODI[30). Wide variation in the preoperative and postoperative ODIs among surgical patients with and without OSA has also been noted, but the relation of the ODI to the AHI and postoperative complications was not assessed. Mutter et al. found that only severe OSA patients were at a significantly increased risk of postoperative complications. Whether hypoxemic and non-hypoxemic severe OSA patients share the same risk or only patients with both severe OSA and hypoxia are at risk is unknown. Our preliminary data suggest that future studies investigating postoperative complications in OSA patients E. P. Deflandre, MD (&) Department of Anaesthesia, Clinique Saint-Luc of Bouge, Belgium & Cabinet Medical ASTES & University of Liege, Liege, Belgium e-mail: eric.deflandre@gmail.com

In reply: Perioperative nocturnal hypoxemia matters in surgical patients with obstructive sleep apnea

To the Editor, We thank Dr. Chung et al. for their interest in our recent letter in which we had highlighted than only a small number of patients exhibit the combination of both nocturnal hypoxemia and severe obstructive sleep apnea (i.e., apnea hypopnea index[30 events per hour). We had suggested that these patients could be at higher risk of postoperative complications. To date, no large database has explored specifically the effect of this combination on outcomes, although Mutter et al. had studied the influence of obstructive sleep apnea (OSA) on outcomes, and Chung et al. had examined the influence of hypoxemia on outcomes. In our letter, we clearly indicated the hypothesis generating nature of our work and noted that it must be confirmed in future studies. Indeed, there are some data indicating that this OSA/nocturnal hypoxemia combination could be deleterious for the patient. For example, Marrone et al. demonstrated in a cohort of patients (from the European Sleep Apnea Database) that the combination of severe OSA and nocturnal hypoxemia might be an important risk factor for kidney dysfunction. We have read with great interest the letter of Chung et al. wherein they highlighted the deleterious influence of nocturnal hypoxemia on the postoperative complication rate. Their letter confirmed to us that future studies must be specifically designed to recognize the possible influence of the nocturnal hypoxemia/severe OSA combination vs nocturnal hypoxemia alone or severe OSA alone. In future studies, special attention should also be directed to identifying patients with thisnocturnal hypoxemia/severe OSA combination in a surgical population (e.g., using screening tools such as STOP-Bang and DES-OSA).

Comparison of clinical scores in their ability to detect hypoxemic severe OSA patients

Background Severe obstructive sleep apnea (sOSA) and preoperative hypoxemia are risk factors of postoperative complications. Patients exhibiting the combination of both factors are probably at higher perioperative risk. Four scores (STOP-Bang, P-SAP, OSA50, and DES-OSA) are currently used to detect OSA patients preoperatively. This study compared their ability to specifically detect hypoxemic sOSA patients. Methods One hundred and fifty-nine patients scheduled for an overnight polysomnography (PSG) were prospectively enrolled. The ability of the four scores to predict the occurrence of hypoxemic episodes in sOSA patients was compared using sensitivity (Se), specificity (Sp), Youden Index, Cohen kappa coefficient, and the area under ROC curve (AUROC) analyses. Results OSA50 elicited the highest Se [95% CI] at detecting hypoxemic sOSA patients (1 [0.89–1]) and was significantly more sensitive than STOP-Bang in that respect. DES-OSA was significantly more specific (0.58 [0.49–0.66]) than the three other scores. The Youden Index of DES-OSA (1.45 [1.33–1.58]) was significantly higher than those of STOP-Bang, P-SAP, and OSA50. The AUROC of DES-OSA (0.8 [0.71–0.89]) was significantly the largest. The highest Kappa value was obtained for DES-OSA (0.33 [0.21–0.45]) and was significantly higher than those of STOP-Bang, and OSA50. Conclusions In our population, DES-OSA appears to be more effective than the three other scores to specifically detect hypoxemic sOSA patients. However prospective studies are needed to confirm these findings in a perioperative setting. Clinical trial registration ClinicalTrials.gov: NCT02050685.

Understanding Pathophysiological Concepts Leading to Obstructive Apnea

Obstructive sleep apnea (OSA) results from a combination of several factors leading to the obstruction of the upper respiratory tract (URT). OSA represents a systemic pathophysiological entity and leads to many comorbidities such as hypertension, coronary ischemia, and stroke. Patients with this pathophysiological entity experience also an increased risk of postoperative complications. Obesity is certainly the main cause of developing OSA. However, many other predisposing factors influence the genesis of obstructive apnea. It is important to understand the complexity of the interactions between predisposing factors to understand the relationship between weight loss following obesity surgery and the improvement in the severity of OSA. In this narrative review, we expose the seven major categories of predisposing factors that interact to generate obstructive apneas in patients, namely the anatomic abnormalities of the URT, the mechanical and the metabolic responses of the upper airway musculature, the loop gain, the arousal threshold, and the hormonal abnormalities. The genesis of apnea is the result of a complex dynamic interaction between the anatomical risk factors and the compensatory neuromuscular reflexes. All of these points are integrally part of the perioperative care of the obese patients. Finally, we will discuss different options for weight reduction.

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Development and Validation of a Morphological Preoperative Obstructive Sleep Apnea Prediction Score: The DES-OSA Score

SESSION TITLE: OSA Posters SESSION TYPE: Poster Presentations PRESENTED ON: Saturday, March 22, 2014 at 01:15 PM 02:15 PM PURPOSE: Obstructive Sleep Apnea (OSA) increases the perioperative risk. We develop a preoperative prediction score based on morphological characteristics. METHODS: Following IRB approvals and informed consent, we included 149 patients scheduled for an overnight polysomnography (OPS). Before OPS, we measured several morphological metrics of their body, face, and neck. According to their value, each of them received a 1, 2 or 3 point(s) score. After the OPS, the AHI (Apnea Hypopnea Index: number of apnea and hypopnea per hour) was collected. Different combinations of morphological metric scores were then summed and tested for their ability to predict a severe OSA (AHI>30). This ability was calculated using ROC curve analysis and prediction probability (PK). A two-tailed P value lower than 0.05 was considered significant. RESULTS: 10 patients were excluded. The best prediction score take account of four parameters: the Mallampati score, the distance between the thyroid and the chin (DTC), the body mass index (BMI) and the neck circumference (NC). According to their value, the parameters were weighted as following (1 point, 2 points, 3 points): Mallampati (Class I, Class II, Class III et IV), DTC in cm (>6, 5-6, 28, >39, >41), NC in cm (>37, >42, >48). The PK for an AHI>30 was 0.868 (95% CI: 0.81-0.92). The area under the curve was 0.83 (95% CI: 0.735-0.926). Sensitivity (Se) and Specificity (Sp), expressed in %, were 100 (Se) and 28.1 (Sp) for a summed score > 3, 73.1 (Se) and 78.9 (Sp) for a summed score >5, and 53.8 (Se) and 94.7 (Sp) for a summed score >6, respectively. CONCLUSIONS: Our study defines a simple morphological score for detecting OSA patients. A score > 3 presents a sensitivity of 100% and a score > 6 presents a specificity of 94.7% to identify an OSA patient with an AHI > 30. CLINICAL IMPLICATIONS: Anesthesiologists could use the DES-OSA score in order to detect OSA patients. The best clinical threshold is a score higher to 5 points. DISCLOSURE: The following authors have nothing to disclose: Eric Deflandre, Vincent Bonhomme, Stephanie Degey, Laurent Cambron, Robert Poirrier, Jean-Francois Brichant, Pol Hans No Product/Research Disclosure Information Copyright