Incidence of perioperative sleep-disordered breathing in patients undergoing major surgery: a prospective cohort study

Background: Major surgery might have a modulating effect on nocturnal breathing patterns. The incidence and course of perioperative sleep-disordered breathing in individuals without a previous diagnosis of obstructive sleep apnea has not been investigated sufficiently so far. Methods: In this study, polygraphic recordings have been obtained from 37 inpatients without a diagnosis of obstructive sleep apnea syndrome during the preoperative night before and six nights following major surgical procedures. Eligible patients consenting to participate in this study underwent polygraphic recordings including four items (O2-saturation, pulse, nasal air flow and snoring) during the study period. Polygraphic data obtained from the postoperative recordings were compared to preoperative recordings. Results: Median (IQR [range]) apnea-hypopnea-index (AHI) for the whole group was 6,0 (2,5 - 14,7 [0–32,6]) in the preoperative night and increased in the following six nights post surgery: second night: 5,6 (2,6-15,0 [1,1 - 59,3]); third night: 16,9 (5,6 - 38,8 [2,9 - 64,3]); fourth night: 11,6 (5,9 - 17,3 [0,4 - 39,3]); fifth night: 15,2 (5,7 - 22,2 [0,2 - 55,5]); sixth night: 22,5 (5,2 - 35,4 [0,2 - 67,7]). AHI-scores of the third to sixth night post surgery differed significantly from data observed in the preoperative night. Conclusion: A significant increase in the AHI occurred frequently after major surgical procedures in the late postoperative period. Sleep-disordered breathings in the late postoperative period deserve attention, as they potentially increase the risk of postoperative complications

Sleep-disordered breathing is a risk factor for delirium after cardiac surgery: a prospective cohort study

INTRODUCTION: Delirium is a frequent complication after cardiac surgery. Although various risk factors for postoperative delirium have been identified, the relationship between nocturnal breathing disorders and delirium has not yet been elucidated. This study evaluated the relationship between sleep-disordered breathing (SDB) and postoperative delirium in cardiac surgery patients without a previous diagnosis of obstructive sleep apnea. METHODS: In this prospective cohort study, 92 patients undergoing elective cardiac surgery with extracorporeal circulation were evaluated for both SDB and postoperative delirium. Polygraphic recordings were used to calculate the apnea-hypopnea index (AHI; mean number of apneas and hypopneas per hour recorded) of all patients preoperatively. Delirium was assessed during the first four postoperative days using the Confusion Assessment Method. Clinical differences between individuals with and without postoperative delirium were determined with univariate analysis. The relationship between postoperative delirium and those covariates that were associated with delirium in univariate analysis was determined by a multivariate logistic regression model. RESULTS: The median overall preoperative AHI was 18.3 (interquartile range, 8.7 to 32.8). Delirium was diagnosed in 44 patients. The median AHI differed significantly between patients with and without postoperative delirium (28 versus 13; P = 0.001). A preoperative AHI of 19 or higher was associated with an almost sixfold increased risk of postoperative delirium (odds ratio, 6.4; 95% confidence interval, 2.6 to 15.4; P <0.001). Multivariate logistic regression analysis showed that preoperative AHI, age, smoking, and blood transfusion were independently associated with postoperative delirium. CONCLUSIONS: Preoperative SDB (for example, undiagnosed obstructive sleep apnea) were strongly associated with postoperative delirium, and may be a risk factor for postoperative delirium. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13054-014-0477-1) contains supplementary material, which is available to authorized users

Verification of Symmetry Detection using PVS

One of the major limitations of model checking is that of state-space explosion. Symmetry reduction is a method that has been successfully used to alleviate this problem for models of systems that consist of sets of identical components. In earlier work, we have introduced a specification language, Promela-Lite, which captures the essential features of Promela but has a fully defined semantics. We used hand proofs to show that a static symmetry detection technique developed for this language is sound, and suitable to be used in a symmetry reduction tool for SPIN. One of the criticisms often levelled at verification implementations, is that they have not been proved mechanically to be correct, i.e., no mechanical formal verification technique has been used to check the soundness of the approach. In this paper, we address this issue by mechanically verifying the correctness of the symmetry detection technique. We do this by embedding the syntax and semantics of Promela-Lite into the theorem prover PVS and using these embeddings to both check the consistency of syntax/semantics definitions, and interactively prove relevant theoretical properties

Central extracorporeal life support with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure

BACKGROUND: The purpose of this prospective study was to evaluate the effects and functional outcome of central extracorporeal life support (ECLS) with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure. METHODS: Between August 2010 and August 2013, 12 consecutive patients (2 female) with a mean age of 31.6 ± 15.1 years received central ECLS with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure. Underlying disease was acute cardiac decompensation due to dilated cardiomyopathy (n = 3, 25%), coronary artery disease with acute myocardial infarction (AMI) (n = 3, 25%), and acute myocarditis (n = 6, 50%). We routinely implemented ECLS by cannulating the ascending aorta, right atrium and inserting a left ventricular decompression cannula vent via the right superior pulmonary vein. RESULTS: All patients were successfully bridged to either recovery (n = 3, 25%), long-term biventricular support (n = 6, 50%) or cardiac transplantation (n = 3, 25%). Seven patients (58.3%) were discharged after a mean hospital stay of 42 ± 11.9 days. The overall survival from ECLS implantation to the end of the study was 58.3%. The cumulative ICU stay was 23.1 ± 9.6 days. The length of support was 8.0 ± 4.3 days (range 3-17 days). CONCLUSIONS: We strongly recommend left ventricular decompression in refractory cardiogenic shock and lung failure to avoid pulmonary edema, left heart distension and facilitate myocardial recovery

Author manuscript, published in &quot;10th International Workshop on Automated Verification of Critical Systems- AVOCS 2010 (2010)&quot; A Simple Model of Communication APIs – Application to Dynamic Partial-order Reduction

Abstract. We are interested in the verification, using model checking, of distributed programs that communicate asynchronously over standard communication APIs such as MPI. This is feasible only if the set of executions that the model checker explores is aggressively reduced to a subset of representative executions, using techniques such as dynamic partial-order reduction. We propose a small set of core primitives in terms of which such APIs can be defined and formally specify these primitives in TLA +. From this specification we derive theorems about the (in)dependence of invocations of the primitives, and use them in a DPOR-based verifier that runs within SimGrid, a simulation framework for distributed programming. Our preliminary experimental results indicate that we obtain good reductions, even though complex network operations are implemented in terms of the core communication primitives.

Model Checking the Pastry Routing Protocol

Proceedings of th