Effect of left paratracheal pressure on left carotid blood flow.

INTRODUCTION: Gautier et al. demonstrated that a compression in the left paratracheal region (left paratracheal pressure, LPP) can be used to seal the oesophagus. However, at this level, the left common carotid artery is very close to the carotid that could be affected during the manipulation. This study aimed to assess the hemodynamic effects of LPP on the carotid blood flow. METHODS: We prospectively included 47 healthy adult volunteers. We excluded pregnant women and people with anomalies of the carotid arteries. The common and internal carotid arteries were preliminarily studied with ultrasounds to exclude atheromatous plaques or vascular malformation. A planimetry of the common and internal carotid arteries was performed. Doppler echography served to measure the peak systolic (PSV) and end-diastolic velocities (EDV) in the common and internal carotid arteries. All measurements were repeated while applying LPP. RESULTS: Forty-seven participants were enrolled (32 women; mean [SD] age: 42 [13] years). The mean PSV difference [95% CI] in the left common carotid artery before and after LPP at the group level was -15.30 [-31.09 to 0.48] cm s-1 (p = .14). The mean surface difference [95% CI] in the left common carotid artery before and after LPP was 24.52 [6.11-42.92] mm2 (p = .11). Similarly, the same surface at the level of the left internal carotid artery changed by -18.89 [-51.59 to 13.80] mm2 after LPP (p = .58). CONCLUSIONS: Our results suggest that LPP does not have a significant effect on carotid blood flow in individuals without a carotid pathology. However, the safety of the manoeuvre should be evaluated in patients at risk of carotid anomalies.

Influence of Different Measurements on the Ability of P-SAP and DES-OSA Scores to Detect Severe Obstructive Sleep Apnea.

BACKGROUND: Severe obstructive sleep apnea (sOSA) represents a risk factor of postoperative complications. Perioperative sleep apnea prediction (P-SAP) and DES-obstructive sleep apnea (DES-OSA) (DES being the acronym for 2 of the participating investigators and OSA for obstructive sleep apnea) scores were validated in the detection of such patients. They include the measurement of neck circumference (NC) and distance between thyroid and chin (DTC). The aim of this study was to evaluate the influence of the measurement method of NC and DTC on the ability of the 2 scores to detect sOSA. METHODS: A total of 371 preoperative patients were enrolled. For each of them, 6 combinations of P-SAP and DES-OSA scores were evaluated. We compared the results of the 6 combinations with the data extracted from the polysomnography (PSG) if available. The ability of the score to detect sOSA patients was evaluated using sensitivity (Se), specificity (Sp), Youden index (YI), area under receiver operating characteristic curve (AUROC), the Probit model, and the Kappa coefficient of Cohen. A P < .05 was considered as significant, a Bonferroni correction was applied if needed. RESULTS: Three hundred and seventy-one patients had a PSG. The Se and the Sp of the DES-OSA score, and the Sp of the P-SAP score, in their ability to detect severe OSA patients, were influenced by the measurement method of the DTC and of the NC. Nevertheless, the AUROC, the Youden index, the Probit model, and the Kappa coefficient of Cohen are not influenced by the variability of measurement. CONCLUSIONS: This study highlights that the measurement method of NC and DTC can influence the results of the 2 scores. We conclude that a strict protocol for the measurement of NC and DTC should be applied (DTC measurement should be performed on a patient with a head in neutral position and the NC measurement should be performed at the cricoid level).

Influence of Sternotomy on Delta Pulse Pressure and Delta Down During Open Chest Cardiac Surgery: A Preliminary Study.

OBJECTIVE: Delta pulse pressure and delta down are used as dynamic preload indicators of fluid responsiveness during closed chest surgery. There are few data regarding their accuracy in open chest surgery. The present study aimed to evaluate the influence of sternotomy on the accuracy of both delta pulse pressure and delta down. DESIGN: Prospective study. SETTING: Single institution, nonacademic hospital. PARTICIPANTS: The study comprised 127 adult patients scheduled for elective open chest cardiac surgery. INTERVENTIONS: Delta pulse pressure and delta down were calculated for all patients before and 10 minutes after sternotomy. MEASUREMENTS AND MAIN RESULTS: Statistical analyses were performed to assess the influence of sternotomy on the accuracy of delta down and delta pulse pressure. Mann-Whitney and Bland-Altman analyses demonstrated a significant influence of sternotomy on delta pulse pressure values but not on delta down values. Among patients who had a positive delta down and/or delta pulse pressure before sternotomy, sternotomy significantly modified the delta pulse pressure value (p = 0.02), but not the delta down value (p = 0.22). The kappa coefficient indicated a very good agreement between delta down before and after sternotomy (0.83) and a fair agreement between delta pulse pressure before and after sternotomy (0.4). The difference between kappa coefficients was highly significant (p < 0.001). CONCLUSIONS: Within the study population, sternotomy significantly influenced delta pulse pressure but not delta down. In this preliminary study, delta down appeared to be more accurate to evaluate fluid responsiveness during open chest surgery than did delta pulse pressure. Before promoting delta down in current practice, confirmation is needed on a larger scale.

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 κ 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 κ 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.

Pleth variability index and fluid management practices: a multicenter service evaluation.

OBJECTIVES: The introduction of a new technology has the potential to modify clinical practices, especially if easy to use, reliable and non-invasive. This observational before/after multicenter service evaluation compares fluid management practices during surgery (with fluids volumes as primary outcome), and clinical outcomes (secondary outcomes) before and after the introduction of the Pleth Variability Index (PVI), a non-invasive fluid responsiveness monitoring. RESULTS: In five centers, 23 anesthesiologists participated during a 2-years period. Eighty-eight procedures were included. Median fluid volumes infused during surgery were similar before and after PVI introduction (respectively, 1000 ml [interquartile range 25-75 [750-1700] and 1000 ml [750-2000]). The follow-up was complete for 60 from these and outcomes were similar. No detectable change in the fluid management was observed after the introduction of a new technology in low to moderate risk surgery. These results suggest that the introduction of a new technology should be associated with an implementation strategy if it is intended to be associated with changes in clinical practice.

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.

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.

Risk factors for nocturnal hypoxemia in severe obstructive sleep apnea patients.

BACKGROUND: Severe obstructive sleep apnea (sOSA) and oxygen desaturations are both risk factors for postoperative complications. In some but not all patients, sOSA is associated with frequent oxygen desaturation episodes during sleep. The aim of this retrospective study was to identify the risk factors for exhibiting oxygen desaturation in patients with sOSA. METHODS: Records of 786 patients, mainly obese (Body Mass Index [mean+SD]=30.2+6.0 kg/m2), were analyzed. Univariate and multivariate analyzes were applied to identify predictive risk factors for oxygen desaturation. Prediction probability was used to test the association between potential risk factors (obesity, age, gender, smoking, alcohol consumption, and benzodiazepines use) and the combination of sOSA and oxygen desaturation. A P value <0.05 was considered as statistically significant. RESULTS: Univariate and multivariate analyses identified five risk factors for oxygen desaturation in the whole population: age (P<0.001), obesity (P<0.001), benzodiazepine use (P<0.001), smoking (P=0.016), and male gender (P=0.029). The same analyses applied to patients with sOSA identified two independent risk factors for oxygen desaturation: obesity (P<0.001), and benzodiazepine use (P=0.017). Obesity obtains the best prediction probability [95% CI] for the combination of sOSA and oxygen desaturation: 0.74 [0.69-0.79]. A BMI >49 kg/m2 was associated with a 50% probability of combining severe OSA and nocturnal oxygen desaturation. CONCLUSIONS: Less than 50% of patients with sOSA experience nocturnal oxygen desaturation. Obesity and daily benzodiazepine intake are independent risk factors for these patients to exhibit nocturnal oxygen desaturation. Benzodiazepine in obese patients with sOSA should, therefore, be used cautiously.

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.