Prevalence of elevated hemoglobin and hematocrit levels in patients with obstructive sleep apnea and the impact of treatment with continuous positive airway pressure: a meta-analysis.

OBJECTIVES: Obstructive sleep apnea (OSA) is reported to be a cause of secondary polycythemia. The present study (i) reviewed the literature reporting the prevalence of secondary polycythemia in patients with OSA and (ii) determined the effect of continuous positive airway pressure (CPAP) therapy on hemoglobin and hematocrit levels in patients with OSA. METHODS: We searched MEDLINE, Embase and Cochrane for studies of adult patients with OSA that reported hemoglobin and/or hematocrit levels. We performed summary estimates of (i) polycythemia prevalence and a subgroup analysis according to OSA severity, and (ii) change in hemoglobin and hematocrit levels following treatment with CPAP. RESULTS: Synthesis of seven studies including 3,654 patients revealed an overall polycythemia prevalence of 2% (95% CI 1-4%); 2% (95% CI 1-3%) in mild-to moderate and 6 % (95% CI 3-12%) in severe OSA. In the pooled analysis of ten single-arm trials including 434 patients, CPAP treatment reduced hemoglobin by 3.76 g/L (95% CI -4.73 to -2.80 g/L). Similarly, pooled analysis of ten single-arm trials including 356 patients without baseline polycythemia showed that CPAP treatment reduced hematocrit by 1.1% (95% CI -1.4 to -0.9%). CONCLUSION: Our pooled analysis supports an increased prevalence of secondary polycythemia in OSA. This estimated prevalence is likely underestimated due to the change in the polycythemia diagnostic criteria in 2016. Future randomized controlled trials are needed to evaluate the effect of CPAP in patients with baseline polycythemia. HIGHLIGHTS: Pooled analysis shows OSA is associated with an increased prevalence of secondary polycythemiaPrevalence of polycythemia is greater in severe OSACPAP treatment for OSA reduces both the hemoglobin and hematocrit.

Impaired cardiac autonomic response in lung transplant patients: A retrospective cohort study.

BACKGROUND: Cardiac autonomic dysfunction (AD) is associated with adverse prognosis in lung disease; however, its implications in lung transplantation have not been previously described. This study evaluated the prevalence of AD in lung transplant (LTx) candidates, its determinants, prognostic implications, and prevalence post-transplant. METHODS: Retrospective one-year study of 103 LTx candidates with AD assessed using heart rate (HR) from the six-minute walk test (6MWT). Impaired chronotropic response index (CRI) was defined as <80% age-adjusted HR during 6MWT. Abnormal HR recovery (HRR) was categorized as reduction in HR ≤ 12 beats/minute after the first minute of 6MWT cessation. RESULTS: Abnormal CRI and HRR were observed in 94% and 76% of patients, respectively. A lower CRI was associated with obstructive lung disease and lower estimated aerobic capacity. CRI was independently associated with 6MW distance [12 m per 10% CRI, P = 0.03], but not with post-transplant cardiovascular events, hospital stay, or one-year mortality. At 3 months post-transplant, no improvement was observed in CRI (99%, n = 66/67, P = 0.25) or HRR (88%, n = 36/41, P = 0.12). CONCLUSION: Cardiac AD was prevalent in LTx candidates and recipients, with chronotropic incompetence a modest contributor to exercise intolerance pretransplant. Further study may help determine whether direct autonomic measures such as HR variability may be more prognostic of LTx outcomes.

Utilization of non-invasive imaging tools for assessment of peripheral skeletal muscle size and composition in chronic lung disease: A systematic review.

OBJECTIVES: Non-invasive imaging modalities allow for detailed assessment of peripheral skeletal muscle wasting, which is associated with increased morbidity and mortality in chronic lung disease. Given the increased utilization of imaging tools, a systematic review was conducted using PRISMA guidelines to describe the modalities and acquisition techniques used to evaluate skeletal muscle in chronic lung disease and assess the relationships of muscle size and composition with strength, physical performance, structural alterations and clinical outcomes. METHODS: Six electronic databases were searched (inception-May 2017) to identify prospective studies measuring peripheral skeletal muscle size or composition using computed tomography (CT), magnetic resonance imaging/spectroscopy (MRI/MRS), or ultrasound (US) in adult chronic lung disease patients. RESULTS: Fifty-eight articles were included, which utilized: CT (n = 26), MRI/MRS (n = 16) and US (n = 16) in 2254 participants. All studies measured muscle size, predominantly of the lower extremity (n = 53), and only nine assessed muscle composition (i.e. fat infiltration) mainly with CT or MRI/MRS (n = 7). Thigh muscle size had a significant association with strength (r = 0.43-0.83, n = 13/14 studies), 6-min walk distance (r = 0.60-0.62, n = 3/6) and physical activity (r = 0.30-0.82, n = 3). Thigh muscle atrophy was independently associated with increased re-hospitalization (n = 1) and mortality (n = 3). Increased muscle fat infiltration had a moderate association with reduced physical performance partly related to increased anaerobic metabolism, but its prognostic utility was not assessed. CONCLUSION: Imaging modalities are valuable tools for the characterization of skeletal muscle dysfunction in chronic lung disease in clinical and research settings. The use of muscle imaging as a prognostic marker is promising and requires further study.

Association between quality of care and complications after abdominal surgery.

BACKGROUND: Measuring the quality of surgical care is essential to identifying areas of weakness in the delivery of effective surgical care and to improving patient outcomes. Our objectives were to (1) assess the quality of surgical care delivered to adult patients; and (2) determine the association between quality of surgical care and postoperative complications. METHODS: This retrospective, pilot, cohort study was conducted at a single university-affiliated institution. Using the institution's National Surgical Quality Improvement Program database (2009-2010), 273 consecutive patients ≥18 years of age who underwent elective major abdominal operations were selected. Adherence to 10 process-based quality indicators (QIs) was measured and quantified by calculating a patient quality score (no. of QIs passed/no. of QIs eligible). A pass rate for each individual QI was also calculated. The association between quality of surgical care and postoperative complications was assessed using an incidence rate ratio, which was estimated from a Poisson regression. RESULTS: The mean overall patient quality score was 67.2 ± 14.4% (range, 25-100%). The mean QI pass rate was 65.9 ± 26.1%, which varied widely from 9.6% (oral intake documentation) to 95.6% (prophylactic antibiotics). Poisson regression revealed that as the quality score increased, the incidence of postoperative complications decreased (incidence rate ratio, 0.19; P = .011). A sensitivity analysis revealed that this association was likely driven by the postoperative ambulation QI. CONCLUSION: Higher quality scores, mainly driven by early ambulation, were associated with fewer postoperative complications. QIs with unacceptably low adherence were identified as targets for future quality improvement initiatives.

Identification of quality of care deficiencies in elderly surgical patients by measuring adherence to process-based quality indicators.

BACKGROUND: The ability to measure surgical quality of care is important and can lead to improvements in patient safety. As such, processes should be carried out in an identical fashion for all patients, regardless of how vulnerable or complex they are. Our objectives were to assess quality of surgical care delivered to elderly patients and to determine the association between patient characteristics and quality of care. STUDY DESIGN: This is a retrospective pilot cohort study, conducted in a single university-affiliated hospital. Using the institution's National Surgical Quality Improvement Program (NSQIP) database (2009 to 2010), 143 consecutive patients 65 years or older, undergoing elective major abdominal surgery, were selected. Adherence to 15 process-based quality indicators (QIs) was measured, and a pass rate was calculated for each individual QI. The association between patient characteristics (age, sex, Charlson Comorbidity Index, functional status, wound class) and patient quality score was assessed using multiple linear regression. RESULTS: Quality indicators with the lowest pass rates included postoperative delirium screening (0%), level of care documentation (0.7%), cognition and functional assessment at discharge (4.9%), oral intake documentation (12.6%), and pressure ulcer risk assessment (35.0%). The mean patient quality score was 46.8% ± 10.7% (range 16.7% to 75.0%). No association was found between patient characteristics and patient quality score. CONCLUSIONS: Quality of care delivered to elderly patients undergoing major surgery at our institution was generally poor and independent of patient characteristics. Although quality appears to be uniform across different patients, these results provide targets for quality improvement initiatives.