The impact of sleep apnea on postoperative utilization of resources and adverse outcomes

Preoperative evaluation and preparation of the morbidly obese patient

PURPOSE OF REVIEW

This review aims to familiarize with the most current findings regarding preoperative evaluation and preparation of morbidly obese patients prior to elective, noncardiac surgery. In the light of the increasing number of surgical patients being morbidly obese, the knowledge of evidence-based preoperative evaluation strategies is profound for a rational approach.

RECENT FINDINGS

Preoperative evaluation should be carried out with sufficient time before the day of surgery to allow modification of the perioperative management. Medical history-taking and physical examination ought to be performed following a standardized scheme especially focussing on the presence of obstructive sleep apnea. Routine testing for fasting glucose and lipoprotein levels should be performed in order to diagnose a metabolic syndrome. ECG recording should be limited to those patients having one or more additional cardiac risk factors or presenting clinical signs of cardiovascular disease or were planned for intermediate or high-risk surgery. Spirometry should be limited to those patients with obstructive sleep apnea or other respiratory findings.

SUMMARY

Synthesis of proper medical history-taking and physical examination as well as detailed search for obstructive sleep apnea and metabolic syndrome are key components of preoperative evaluation. Further testing should be based on the findings of these steps and comprise the cardiac risk of the surgical procedure.

Postoperative respiratory failure necessitating transfer to the intensive care unit in orthopedic surgery patients: risk factors, costs, and outcomes

Background

Postoperative pulmonary complications in orthopedic surgery patients have been associated with worse clinical outcomes. Identifying patients with respiratory risk factors requiring enhanced monitoring and management modifications is an important part of postoperative care. Patients with unanticipated respiratory decompensation requiring transfer to the intensive care unit (ICU) have not been studied in sufficient detail.

Methods

A retrospective case-control study of elective orthopedic surgery patients (knee, hip, shoulder, or spine, n = 51) who developed unanticipated respiratory failure (RF) necessitating transfer to the ICU over a 3-year period was conducted. Controls (n = 153) were frequency matched to cases by gender, age, and surgical procedure. Patient and perioperative care factors, clinical outcomes, and cost of care were examined.

Results

Transfer to the ICU occurred within 48 h of surgery in 73 % of the cases, 31 % required non-invasive ventilation, and 18 % required mechanical ventilation. Cases had a higher prevalence of chronic obstructive pulmonary disease (COPD), obstructive sleep apnea (OSA), and regular psychotropic medication use than controls. Cases received more intravenous opioids during the first 24 postoperative hours, were hospitalized 4 days longer, had higher in-hospital mortality, and had excess hospitalization costs of US$26,571. COPD, OSA, preoperative psychotropic medications, and anesthesia time were associated with risk of RF in a multivariate analysis.

Conclusions

Unanticipated RF after orthopedic surgery is associated with extended hospitalization, increased mortality, and higher cost of care. Hospital protocols that include risk factor assessment, enhanced monitoring, and a cautious approach to opioid use in high-risk patients may reduce the frequency of this complication.

Factors predisposing to worsening of sleep apnea in response to fluid overload in men

OBJECTIVES

Obstructive sleep apnea (OSA) is highly prevalent in patients with fluid-retaining conditions. Using bioimpedance measurements, previous studies have shown that the greater the amount of fluid redistributed from the legs to the neck overnight, the greater the severity of OSA. Our objective was to investigate factors that predispose the development or worsening of OSA in response to experimental fluid overload.

METHODS

Fifteen normotensive and non-obese adult men with and without OSA underwent polysomnography (PSG) during which normal saline was infused intravenously at a minimal rate to keep the vein open (control) or as a bolus of 22 ml/kg body weight (approximately 2 L) in a random order and crossed over after a week.

RESULTS AND CONCLUSIONS

Before and after sleep, neck circumference and bioimpedance were measured to calculate neck resistance, reactance, phase angle, and fluid volume. Subjects who experienced more than a twofold increase in apnea-hypopnea index (AHI) or obstructive AHI from control to intervention and had an AHI>10 during intervention were considered susceptible to the development or worsening of OSA. Baseline neck circumference and phase angle before saline infusion were independently associated with increased susceptibility to developing or worsening OSA in response to saline infusion. In non-obese men, a larger neck circumference and bioimpedance phase angle of the neck, which may be associated with larger pharyngeal tissue content, is associated with increased susceptibility for worsening of OSA in response to fluid overloading.

Use of a home positive airway pressure device during intraoperative monitored anesthesia care for outpatient surgery

Perioperative positive airway pressure (PAP) is recommended by the American Society of Anesthesiologists for patients with obstructive sleep apnea, but a readily available and personalized intraoperative delivery system does not exist. We present the successful use of a patient's own nasal PAP machine in the operating room during outpatient foot surgery which required addition of a straight adaptor for oxygen delivery and careful positioning of the gas sampling line to permit end-tidal carbox dioxide monitoring. Home PAP machines may provide a potential alternative to more invasive methods of airway management for patients with obstructive sleep apnea under moderate sedation.

CPAP in the Perioperative Setting: Evidence of Support

OSA is a commonly encountered comorbid condition in surgical patients. The risk of cardiopulmonary complications is increased by two to threefold with OSA. Among the different treatment options for OSA, CPAP is an efficacious modality. This review examines the evidence regarding the use of CPAP in the preoperative and postoperative periods in surgical patients with diagnosed and undiagnosed OSA.

Perioperative sleep apnea: a real problem or did we invent a new disease?

Depending on the subpopulation, obstructive sleep apnea (OSA) can affect more than 75% of surgical patients. An increasing body of evidence supports the association between OSA  and perioperative complications, but some data indicate important perioperative outcomes do not differ between patients with and without OSA. In this review we will provide an overview of the pathophysiology of sleep apnea and the risk factors for perioperative complications related to sleep apnea. We also discuss a clinical algorithm for the identification and management of OSA patients facing surgery.

Validation of the STOP-Bang Questionnaire as a Screening Tool for Obstructive Sleep Apnea among Different Populations: A Systematic Review and Meta-Analysis

BACKGROUND

Diagnosing obstructive sleep apnea (OSA) is clinically relevant because untreated OSA has been associated with increased morbidity and mortality. The STOP-Bang questionnaire is a validated screening tool for OSA. We conducted a systematic review and meta-analysis to determine the effectiveness of STOP-Bang for screening patients suspected of having OSA and to predict its accuracy in determining the severity of OSA in the different populations.

METHODS

A search of the literature databases was performed. Inclusion criteria were: 1) Studies that used STOP-Bang questionnaire as a screening tool for OSA in adult subjects (>18 years); 2) The accuracy of the STOP-Bang questionnaire was validated by polysomnography--the gold standard for diagnosing OSA; 3) OSA was clearly defined as apnea/hypopnea index (AHI) or respiratory disturbance index (RDI) ≥ 5; 4) Publications in the English language. The quality of the studies were explicitly described and coded according to the Cochrane Methods group on the screening and diagnostic tests.

RESULTS

Seventeen studies including 9,206 patients met criteria for the systematic review. In the sleep clinic population, the sensitivity was 90%, 94% and 96% to detect any OSA (AHI ≥ 5), moderate-to-severe OSA (AHI ≥15), and severe OSA (AHI ≥30) respectively. The corresponding NPV was 46%, 75% and 90%. A similar trend was found in the surgical population. In the sleep clinic population, the probability of severe OSA with a STOP-Bang score of 3 was 25%. With a stepwise increase of the STOP-Bang score to 4, 5, 6 and 7/8, the probability rose proportionally to 35%, 45%, 55% and 75%, respectively. In the surgical population, the probability of severe OSA with a STOP-Bang score of 3 was 15%. With a stepwise increase of the STOP-Bang score to 4, 5, 6 and 7/8, the probability increased to 25%, 35%, 45% and 65%, respectively.

CONCLUSION

This meta-analysis confirms the high performance of the STOP-Bang questionnaire in the sleep clinic and surgical population for screening of OSA. The higher the STOP-Bang score, the greater is the probability of moderate-to-severe OSA.

Clinical consequences and economic costs of untreated obstructive sleep apnea syndrome

Objective

To provide an overview of the healthcare and societal consequences and costs of untreated obstructive sleep apnea syndrome.

Data sources

PubMed database for English-language studies with no start date restrictions and with an end date of September 2014.

Methods

A comprehensive literature review was performed to identify all studies that discussed the physiologic, clinical and societal consequences of obstructive sleep apnea syndrome as well as the costs associated with these consequences. There were 106 studies that formed the basis of this analysis.

Conclusions

Undiagnosed and untreated obstructive sleep apnea syndrome can lead to abnormal physiology that can have serious implications including increased cardiovascular disease, stroke, metabolic disease, excessive daytime sleepiness, work-place errors, traffic accidents and death. These consequences result in significant economic burden. Both, the health and societal consequences and their costs can be decreased with identification and treatment of sleep apnea.

Implications for practice

Treatment of obstructive sleep apnea syndrome, despite its consequences, is limited by lack of diagnosis, poor patient acceptance, lack of access to effective therapies, and lack of a variety of effective therapies. Newer modes of therapy that are effective, cost efficient and more accepted by patients need to be developed.

Obstructive sleep apnea and adverse outcomes in surgical and nonsurgical patients on the wards

BACKGROUND

Obstructive sleep apnea (OSA) has been associated with clinical deterioration in postoperative patients and patients hospitalized with pneumonia. Paradoxically, OSA has also been associated with decreased risk of inpatient mortality in these same populations.

OBJECTIVES

To investigate the association between OSA and in-hospital mortality in a large cohort of surgical and nonsurgical ward patients.

DESIGN

Observational cohort study.

SETTING

A 500-bed academic tertiary care hospital in the United States.

PATIENTS

A total of 93,676 ward admissions from 53,150 unique adult patients between November 1, 2008 and October 1, 2013.

INTERVENTION

None.

MEASUREMENTS

OSA diagnoses and comorbidities were identified by International Classification of Diseases, Ninth Revision, Clinical Modification codes. Logistic regression was used to control for patient characteristics, location prior to ward admission, and admission severity of illness. The primary outcome was in-hospital death. Secondary outcomes included rapid response team (RRT) activation, intensive care unit (ICU) transfer, intubation, and cardiac arrest on the wards.

MAIN RESULTS

OSA was identified in 5,625 (10.6%) patients. Patients with OSA were more likely to be older, male, and obese, and had higher rates of comorbidities. OSA patients had more frequent RRT activations (1.5% vs 1.1%) and ICU transfers (8% vs 7%) than controls (P < 0.001 for both comparisons), but a lower inpatient mortality rate (1.1% vs 1.4%, P < 0.05). OSA was associated with decreased adjusted odds for ICU transfer (odds ratio [OR]: 0.91 [0.84-0.99]), cardiac arrest (OR: 0.72 [0.55-0.95]), and in-hospital mortality (OR: 0.70 [0.58-0.85]).

CONCLUSIONS

After adjustment for important confounders, OSA was not associated with clinical deterioration on the wards and was associated with significantly decreased in-hospital mortality.

Identifying Obstructive Sleep Apnea in Administrative Data

Background:

Health administrative (HA) databases are increasingly used to identify surgical patients with obstructive sleep apnea (OSA) for research purposes, primarily using diagnostic codes. Such means to identify patients with OSA are not validated. The authors determined the accuracy of case-ascertainment algorithms for identifying patients with OSA with the use of HA data.

Methods:

Clinical data derived from an academic health sciences network within a universal health insurance plan were used as the reference standard. The authors linked patients to HA data and retrieved all claims in the 2 yr before surgery to determine the presence of any diagnostic codes, diagnostic procedures, or therapeutic interventions consistent with OSA.

Results:

The authors identified 4,965 patients (2003 to 2012) who underwent preoperative polysomnogram. Of these, 4,353 patients were linked to HA data; 2,427 of these (56%) had OSA based on diagnosis by a sleep physician or the apnea hypopnea index. A claim for a polysomnogram and receipt of a positive airway pressure device had a sensitivity, specificity, and positive likelihood ratio (+LR) for OSA of 19, 98, and 10.9%, respectively. An International Classification of Diseases, Tenth Revision, code for sleep apnea in hospitalization abstracts was 9% sensitive and 98% specific (+LR, 4.5). A physician billing claim for OSA (International Classification of Diseases, Ninth Revision, 780.5) was 58% sensitive and 38% specific (+LR, 0.9). A polysomnogram and a positive airway pressure device or any code for OSA was 70% sensitive and 36% specific (+LR, 1.1).

Conclusions:

No code or combination of codes provided a +LR high enough to adequately identify patients with OSA. Existing studies using administrative codes to identify OSA should be interpreted with caution.

Relationship between Chronic Intermittent Hypoxia and Intraoperative Mean Arterial Pressure in Obstructive Sleep Apnea Patients Having Laparoscopic Bariatric Surgery

Background:

Recurrent nocturnal hypoxemia in obstructive sleep apnea enhances sympathetic function, decreases baroreceptor sensitivity, and weakens peripheral vascular responses to adrenergic signals. The authors hypothesized that the percentage of total sleep time spent at oxyhemoglobin saturation (Sao2) less than 90% and minimum nocturnal Sao2 on preoperative polysomnography are associated with decreased intraoperative mean arterial pressure.

Methods:

The authors examined the records of all patients who had laparoscopic bariatric surgery at Cleveland Clinic between 2005 and 2009 and an available polysomnography study. The authors assessed the relationships between the percentage of total sleep time spent at Sao2 less than 90% and minimum nocturnal Sao2, and the time-weighted average of mean arterial pressure. The authors used multivariable regression models to adjust for prespecified clinical confounders.

Results:

Two hundred eighty-one patients were included in the analysis. The average change in the time-weighted average of mean arterial pressure was −0.02 (97.5% CI, −0.08, 0.04) mmHg for each 1% absolute increase in the percentage of sleep time spent at Sao2 less than 90% (P = 0.50). The average change was −0.13 (97.5% CI, −0.27, 0.01) mmHg, for each 1% absolute decrease in the minimum Sao2 (P = 0.04 &gt; significance criterion of 0.025, Bonferroni correction). An unplanned analysis estimated 1% absolute decrease in minimum Sao2 was associated with −0.22 (98.75% CI, −0.39, −0.04) mmHg, change in mean arterial pressure (P = 0.002) in the time period between endotracheal intubation and trocar insertion.

Conclusion:

Recurrent nocturnal hypoxemia in obstructive sleep apnea is not a risk marker for intraoperative hypotension.

Obstructive sleep apnea in adult patients: considerations for anesthesia and acute pain management

Obstructive sleep apnea (OSA) represents a challenge in the perioperative period for both physicians and the health care system alike. A number of studies have associated OSA with increased risk for postoperative complications. This is of particular concern in the face of this disease remaining vastly underdiagnosed. In this context, current guidelines and established concepts such as the use of continuous positive airway pressure or the level of postoperative monitoring, lack strong scientific evidence. Other interventions such as the use neuraxial/regional anesthesia may however offer added benefit. This review aims to address considerations for physicians in charge of OSA patients in the perioperative setting and to give an outlook for current and future research on this topic.

A Matched Cohort Study of Postoperative Outcomes in Obstructive Sleep Apnea

Background:

Obstructive sleep apnea (OSA) is associated with increased risk of postoperative complications. The authors investigated whether preoperative diagnosis and prescription of continuous positive airway pressure therapy reduces these risks.

Methods:

Matched cohort analysis of polysomnography data and Manitoban health administrative data (1987 to 2008). Postoperative outcomes in adult OSA patients up to 5 yr before (undiagnosed OSA, n = 1,571), and any time after (diagnosed OSA, n = 2,640) polysomnography and prescription of continuous positive airway pressure therapy for a new diagnosis of OSA, were compared with controls at low risk of having sleep apnea (n = 16,277). Controls were matched by exact procedure, indication, and approximate date of surgery. Procedures used to treat sleep apnea were excluded. Follow-up was at least 7 postoperative days. Results were reported as odds ratio (95% CI) for OSA or subgroup versus controls.

Results:

In multivariate analyses, the risk of respiratory complications (2.08 [1.35 to 3.19], P &lt; 0.001) was similarly increased for both undiagnosed and diagnosed OSA. The risk of cardiovascular complications, primarily cardiac arrest and shock, was significantly different (P = 0.009) between undiagnosed OSA (2.20 [1.16 to 4.17], P = 0.02) and diagnosed OSA patients (0.75 [0.43 to 1.28], P = 0.29). For both outcomes, OSA severity, type of surgery, age, and other comorbidities were also important risk modifiers.

Conclusions:

Diagnosis of OSA and prescription of continuous positive airway pressure therapy were associated with a reduction in postoperative cardiovascular complications. Despite limitations in the data, these results could be used to justify and inform large efficacy trials of perioperative continuous positive airway pressure therapy in OSA patients.