The pickwickian syndrome-obesity hypoventilation syndrome

Comparison of physical activity and quality of life between obese individuals with obstructive sleep apnea syndrome and individuals with obesity hypoventilation syndrome

PURPOSE

Obstructive Sleep Apnea Syndrome (OSAS) and Obesity Hypoventilation Syndrome (OHS) share common causal factors and comorbidities but may have a variable effect on physical activity and associated quality of life, due to differences in pathophysiology. The aim of this study was to compare the levels of physical activity, mental health and quality of life between matched obese patients with either OSAS or OHS, aiming to identify which of the two syndromes may impose the most severe impact on these variables, for the first time in literature.

METHODS

A total of 76 obese patients (OSAS: Ν1 = 48, OHS: N2 = 26) of similar age (58.2 ± 12.2 vs. 63.6 ± 9.8; p > 0.05), BMI (37.2 ± 6.2 vs. 40.3 ± 7.3; p > 0.05), and Apnea-Hypopnea Index (AHI) under non-invasive ventilation, completed International Physical Activity Questionnaire (IPAQ), Short-Form Health Questionnaire (SF-36), Personal Well-Being (PWB) Scale and Hospital Anxiety and Depression Scale (HADS-A and HADS-D), in this cross-sectional study.

RESULTS

Both groups had similar scores in SF-36, HADS-A and HADS-D, while prevalence of clinical cases of anxiety (HADS-A > 8) and depression (HADS-D > 8) were also similar. OSAS patients scored significantly higher in physical activity [absolute IPAQ values 1100.75(7753.5) for OSAS vs. 518(3806) for OHS; p = 0.029]. Group comparisons yielded significant differences in physical functioning (p < 0.05) and general health perceptions (p < 0.05), in favor of the OSAS group.

CONCLUSION

Both syndromes significantly affect patients' quality of life and physical activity, with the burden being heavier for OHS patients. Daily physical activity seems to be more impaired among obese OHS patients perhaps due to daytime hypercapnia.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Respiratory Center Function and Its Impact in Obesity Hypoventilation Syndrome Treatment

INTRODUCTION

Patients with obesity hypoventilation syndrome (OHS) need treatment with positive pressure either with continuous (CPAP) or double pressure (NIV). The apnea-hypopnea index (AHI) is considered a key data for making therapeutic decisions. We hypothesized that HR may be an useful tool to establish different phenotypes and individualize treatment in patients with OHS. Our objective was to analyze the role of the respiratory center response to hypercapnia (HR) in the adequacy of positive airway pressure therapy.

METHOD

We included subjects with OHS treated with CPAP or NIV according to AHI and baseline pCO₂. We analyzed therapeutic effectiveness and treatment changes prioritizing CPAP if AHI>30/h. Therapy was considered adequate if it was effective after two years. HR was measured with the p0.1/pEtCO₂ ratio and its capability to select therapy was analyzed. The statistical study was performed by means comparison (Student's t) and multivariate analysis (logistic regression).

RESULTS

67 subjects were included of 68(11) years old, 37 (55%) males, initially 45 (67%) treated with NIV and 22 (33%) with CPAP, one case was excluded and in 25 (38%) the treatment was changed. Finally, CPAP was adequate for 29 subjects (44%) and NIV for 37 (56%). The CPAP group showed AHI 57/h (24) and p0.1/pEtCO₂ 0.37cmH₂O/mmHg (0.23), NIV group AHI 43/h (35) and p0.1/pEtCO₂ 0.24 (0.15) with p=0.049 and 0.006. In multivariate analysis, p0.1/pEtCO₂ (p=0.033) and AHI>30 (p=0.001) were predictors of adequate therapy.

CONCLUSION

Measuring the RH of the respiratory center helps to select the most appropriate treatment for patients with OHS.

Obstructive Sleep Apnea: A Case Report

Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper airway blockage and collapse during sleep accompanied by awakenings with or without oxygen desaturations. During obstructive sleep apnea events, the oropharynx in the back of the throat compresses, causing arousal, oxygen desaturation, or both, leading to fragmented sleep. The hyperplastic uvula is a common clinical finding in patients with obstructive sleep apnea. The various diagnostic and treatment modalities of obstructive sleep apnea are discussed in this article.

EFFECTS OF DIEP FLAP-BASED BREAST RECONSTRUCTION ON RESPIRATORY FUNCTION

BACKGROUND

Breast reconstruction (BR) is an essential part of breast cancer treatment, and the DIEP flap is considered the gold standard reconstruction technique, which uses a free abdominal flap. Concerns have been raised regarding the effects of abdominoplasty on respiratory functions. This topic has not been addressed regarding donor-site closure of DIEP flaps. Our aim is to prospectively compare preoperative and postoperative spirometry in patients undergoing DIEP flap-based BR, investigating its impact on respiratory function.

MATERIALS AND METHODS

We enrolled 21 patients who received BR with DIEP flap in our institution, who underwent pulmonary function assessment by spirometry 1 month preoperatively and 1 year postoperatively. We assessed Forced Expiratory Volume in the first second (FEV1), Forced Vital Capacity (FVC), FEV1/FVC ratio, and Peak Expiratory Flow (PEF). Statistical analysis was performed using the paired samples test.

RESULTS

An improvement in the mean values of all 4 variables was found at 1 year from surgery. Namely, FEV1 improved by 0.1 L with a standard deviation (SD) of 0.39 L, FVC by 0.04 L with SD of 0.627, FEV1/FVC by 2.11 L with SD of 7.85 L, and PEF by 1.2 L with SD of 1.45 L. Only PEF was statistically significant [P = 0.001].

CONCLUSION

Our results suggest that DIEP flap BR does not negatively impact respiratory function. Although further knowledge is required, we confirm the possibility of considering the indication for abdominoplasty and DIEP flap reconstruction in patients with altered and reduced pulmonary function.

A Scoping Review of Sleep Apnea: Where Do We Stand?

Obstructive sleep apnea (OSA), a condition in which there is a recurrent collapse of the upper airway while sleeping, is a widespread disease affecting 5% to 10% people worldwide. Despite several advances in the treatment modalities for OSA, morbidity and mortality remain a concern. Common symptoms include loud snoring, gasping for air during sleep, morning headache, insomnia, hypersomnia, attention deficits, and irritability. Obese individuals, male gender, older age (65+), family history, smoking, and alcohol consumption are well recognized risk factors of OSA. This condition holds the ability to increase inflammatory cytokines, cause metabolic dysfunction, and increase the sympathetic output, all of which exacerbate OSA due to their effect on the cardiovascular system. In this review, we discuss its brief history, risk factors, complications, treatment modalities, and the role of clinicians in curbing its risk.

A Novel Nomogram and Online Calculator for Predicting the Risk of Obesity Hypoventilation Syndrome in Bariatric Surgery Candidates

BACKGROUND

Obesity hypoventilation syndrome (OHS) is frequently misdiagnosed and undertreated, increasing the risk of perioperative complications. We aimed to determine the predictors of OHS and to develop and validate a novel nomogram and online calculator for identifying patients at risk of OHS in bariatric surgery candidates.

METHODS

We retrospectively analyzed the data of patients undergoing bariatric surgery between March 2017 and June 2020. Predictors were identified using univariate and multivariate analyses to establish the nomogram. The discriminative ability, calibration, and clinical value of the nomograms were tested using C-statistics, calibration plots, and decision curve analysis. The nomogram was internally validated using bootstrap resampling.

RESULTS

A total of 577 patients were enrolled, and OHS was presented in 17.9% (103/577). Body mass index (BMI) (odds ratio [OR], 1.11; 95% confidence interval (CI), 1.04-1.18; p = 0.001), neck circumference (OR, 1.09; 95% CI, 1.01-1.18; p = 0.035), type 2 diabetes (T2D) (OR, 2.02; 95% CI, 1.17-3.45; p = 0.011), serum bicarbonate (OR, 1.47; 95% CI, 1.30-1.67; p < 0.001), and C-reactive protein (CRP) (OR, 1.03; 95% CI, 1.01-1.06; p = 0.017) were independent risk factors for OHS and incorporated to develop the nomogram. The nomogram revealed good discrimination, with a C-index of 0.830 (95% CI: 0.784-0.876) (0.8227 through internal validation), and good calibration. Decision curve analysis further confirmed the nomogram's clinical usefulness.

CONCLUSIONS

The novel nomogram and online calculator provided an excellent preoperative individualized prediction of OHS in patients undergoing bariatric surgery, hereby potentially assisting clinicians and surgeons in the early detection and intensive monitoring of OHS.

Adherence to Positive Airway Pressure Therapy in Obesity Hypoventilation Syndrome

Because of the prevalence of extreme obesity in the United States, there has been an increase in prevalence of obesity hypoventilation syndrome (OHS). There is limited information on the characteristics and pattern of positive airway pressure (PAP) adherence in patients with OHS compared with eucapnic patients with obstructive sleep apnea (OSA). This article discusses in detail the impact of PAP therapy on outcomes in patients with OHS, compares adherence between continuous PAP and noninvasive ventilation in OHS, and compares PAP adherence in patients with OHS to patients with moderate to severe OSA enrolled in clinical trials designed to improve CPAP adherence.

Severe paediatric obesity and sleep: A mutual interactive relationship!

Childhood severe obesity is a serious, urgent and complex global health problem with long-term co-morbidities. Obstructive sleep-disordered breathing is more common in obese children and adolescents. Increased body mass index is associated with an increase in apnea-hypopnea index. Obstructive sleep apnea leads to a decrease in rapid eye movement sleep, and obese children have been noted to have a decrease in rapid eye movement sleep, leading to weight gain. Short sleep duration and poor sleep quality are associated with childhood obesity and cardiometabolic risks. Public health strategies for obesity prevention should focus more on sleep. Targeting childhood obesity is important in the prevention and management of obstructive sleep-disordered breathing.

Effect of ventilation therapy on mortality rate among obesity hypoventilation syndrome and obstructive sleep apnoea patients

INTRODUCTION

The prevalence of obesity is continually increasing worldwide, which increases the incidence of obesity hypoventilation syndrome (OHS) and its consequent mortality.

METHODS

We reviewed the therapy mode, comorbidity and mortality of all OHS patients treated at our hospital between 2005 and 2016. The control group consisted of randomly selected patients with obstructive sleep apnoea (OSA) treated during the same period.

RESULTS

We studied 206 OHS patients and 236 OSA patients. The OHS patients were older (56.3 versus 52.3 years, p<0.001) and heavier (body mass index 46.1 versus 32.2 kg·m-2, p<0.001), and the percentage of women was higher (41.2% versus 24.2%, p<0.001), respectively. The OHS patients had more hypertension (83% versus 61%, p<0.001) and diabetes (62% versus 31%, p<0.001) than the OSA patients, but no higher stroke (4% versus 8%, p=0.058) or ischaemic heart disease (14% versus 15%, p=0.437) incidence. The 5- and 10-year, unadjusted survival rates were lower among the OHS patients than among the OSA patients (83% versus 96% and 74% versus 91%, respectively; p<0.001). Differences in mortality rates were not related to age, sex or body mass index; covariates such as Charlson Comorbidity Index and ventilation therapy predicted survival. The mortality rate decreased significantly (p<0.001) both in OHS and OSA patients even after adjusting for covariates.

CONCLUSIONS

The mortality rate in OHS was significantly higher than that in OSA patients even after adjusting for covariates. Ventilation therapy by continuous positive airway pressure or noninvasive ventilation have reduced mortality significantly in all patients.

Evaluation of Nocturnal Respiratory Complaints in Pregnant Women

Snoring during pregnancy increases the risk of low Apgar score and low birth weight of newborns. Snoring women are twice as likely to be diagnosed as having preeclampsia when compared to non-snoring ones. Snoring may also be linked to, albeit it is not a prerequisite for, apneic events at sleep. The aim of this survey-type study was to evaluate the occurrence and severity of nocturnal respiratory complaints in a group of 312 pregnant women. Problems associated with snoring and other nasopharyngeal symptoms were reported by 60% of women. Complaints were more frequent in patients with a higher body mass index. The symptoms were significantly more frequent in the group of snorers. The results of this study suggest a pattern of basic features in pregnancy, such as snoring, overweight, and upper airway symptoms, which all ought to direct attention of care givers to the diagnostics of sleep-related breathing disorders. The early diagnosis would enable to undertake the measures to prevent preterm labor and to avoid postpartum complications in both mother and newborn.

Is Obesity Hypoventilation Syndrome A Postmenopausal Disorder?

Previous studies have assessed the role of gender and menopause in Obstructive Sleep Apnea (OSA). It is well known that menopause is a major risk factor for OSA. However, analogous studies on obesity Hypoventilation Syndrome (OHS) are limited. Recent studies have suggested that OHS is more prevalent in postmenopausal women. Moreover, women with OHS seem to have excess comorbidities, including hypothyroidism, hypertension, pulmonary hypertension, and diabetes mellitus, compared to men. In the present perspective, we discuss recent data on the prevalence and comorbidities associated with OHS in women, as well as the use of noninvasive ventilation in women with OHS, and try to answer the question, “Is OHS a disorder of postmenopausal women?”

Efficacy of bilevel ventilatory support in the treatment of stable patients with obesity hypoventilation syndrome: systematic review and meta-analysis

OBJECTIVE

To systematically review the effects of bilevel ventilatory support (BVS) in patients with Obesity Hypoventilation Syndrome (OHS).

METHODS

A search of databases (MEDLINE accessed by PubMed, Cochrane CENTRAL, EMBASE and LILACS) was conducted from inception to June 2018. Randomized trials comparing BVS to other therapeutic modalities such as lifestyle counseling, continuous positive airway pressure (PAP) or BVS with average volume assured pressure support for the treatment of patients with OHS were included. The primary outcome was a change in daytime arterial carbon dioxide levels (PaCO₂). Secondary outcome measures included arterial partial pressure of oxygen (PaO₂), blood bicarbonate (HCO₃), percentage of total sleep time (TST) with oxygen saturation <90%, transcutaneous pressure of carbon dioxide (PtcCO₂), Epworth Sleepiness Scale (ESS), Medical Outcome Survey Short Form (SF36), Functional Outcomes of Sleep Questionnaire (FOSQ), Severe Respiratory Insufficiency Questionnaire (SRI), compliance with treatment, and weight loss.

RESULTS

Of 176 articles identified, seven studies were included. When BVS was compared to lifestyle counseling, the intervention was superior in improving PaCO₂ (-2.90 mmHg; 95%CI -4.28 to -1.52), PaO₂ (2.89 mmHg; 95%CI 0.33 to 5.46), HCO₃ (-2.55 mmol/L; 95%CI -3.28 to -1.81), percentage of TST<90% (-30.55%; 95%CI -37.98 to -23.12), ESS (-2.52; 95%CI -4.16 to -0.88) and FOSQ (6.33; 95%CI 1.78 to 10.88). However, when BVS was compared to other PAP modalities, there was no difference in any of the outcomes evaluated.

CONCLUSIONS

Treatment using BVS therapy is superior to lifestyle counseling. Different PAP modalities appear to be equally effective in improving outcomes. CRD42017065326.

Correlation between metabolic syndrome and sleep apnea

The so-called “metabolic syndrome” (MS), constitutes a cluster of metabolic and cardiovascular abnormalities, including fasting glucose, blood pressure, triglycerides, high density lipoprotein cholesterol (HDL-C), and waist circumference that arise from insulin resistance. Obstructive sleep apnea (OSA) syndrome is characterized by recurrent episodes of partial or complete obstruction of the upper airway, involving cessation or significant decreased airflow, with intermittent hypoxemia, frequent arousals from sleep and recurrent oxyhemoglobin desaturations that interfere with normal sleep patterns generating difficulty falling asleep, unrefreshing sleep and loud snoring. The relation between these two entities is known as “Syndrome Z”, and there is no question about the impact of these risk factors on health and disease. This clinical condition presents a growing epidemic Worldwide, affecting approximately 60% of the general population with both MS and OSA due to the constant increase of body mass index in humans. This article presents evidence-based data that focuses on the direct relationship between MS and OSA.

Prevalence and severity of syndrome Z in women with metabolic syndrome on waiting list for bariatric surgery: a cross-sectional study

BACKGROUND

In recent years, obesity has become one of the most important public health problems in the world, with a growing prevalence in both developed and developing countries. Recent studies show that sleep disturbances, especially obstructive sleep apnoea (OSA) may be a manifestation of metabolic syndrome (MetS). Although the association of OSA with the MetS is largely attributed to obesity, the exact pathophysiological mechanisms and their individual characteristics still need to be identified. This study investigated the prevalence and severity of syndrome Z in obese women with MetS on waiting list for bariatric surgery.

METHODS

In this double-center cross-sectional study, female patients aged ≥18 years, stage III severe obesity with MetS, on waiting list for bariatric surgery were recruited. The diagnosis for MetS was made according to the criteria of the national cholesterol education program, adult treatment panel III. Clinical, anthropometric, demographic, biochemistry, and sleep measurements were collected. Correlations between continuous variables with sleep parameters were performed using the Pearson correlation test or Spearman correlation test.

RESULTS

The mean age of 83 patients was 44.8 ± 11.2 years and mean BMI was 42.6 ± 8.1 kg/m². There was a significant correlation between OSA and metabolic score (r = 0.336; P = 0.002), neck circumference (r = 0.218; P = 0.048), basal systolic blood pressure (r = 0.280; P = 0.01), total cholesterol (r = 0.277; P = 0.011) and abdomen circumference (r = 0.284; P = 0.009). The mean values of excessive daytime sleepiness were 10.5 ± 7 demonstrating a value considered normal for its presence. However, a high risk for OSA was observed in practically the entire population. It was observed that the prevalence of Syndrome Z (75.9%) increased significantly according to apnoea hypopnoea index (AHI) (P for trend <0.0000). A prevalence of 27.71% for mild OSA, 20.48% for moderate OSA, and 27.71% for severe OSA was observed. An association of AHI severity with all components of MetS was also observed.

CONCLUSIONS

We can conclude that syndrome Z presents a high prevalence in a female population with MetS and a considerable severity according to the presence of OSA. Therefore, patients with MetS should be investigated for the presence of sleep disorders. Trial registration The study has been registered on ClinicalTrials.gov NCT02409160 and followed the standards of The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: guidelines for reporting observational studies.

Gender differences in patients with obesity hypoventilation syndrome

The role of gender and menopause in obstructive sleep apnoea is well known; however, no study has reported the impact of gender on the clinical presentation and the nocturnal respiratory events in patients with obesity hypoventilation syndrome. Therefore, this study prospectively evaluated differences in the clinical characteristics of women and men with obesity hypoventilation syndrome in a large cohort of patients with obstructive sleep apnoea. During the study period, a total of 1973 patients were referred to the sleep clinic with clinical suspicion of obstructive sleep apnoea. All patients underwent overnight polysomnography, during which time spirometry, arterial blood samples and thyroid tests were routinely obtained. Among 1973 consecutive patients, 1693 (617 women) were diagnosed with obstructive sleep apnoea, among whom 144 suffered from obesity hypoventilation syndrome (96 women). The prevalence of obesity hypoventilation syndrome among women and men was 15.6% and 4.5%, respectively (P < 0.001). Women with obesity hypoventilation syndrome were significantly older than men with obesity hypoventilation syndrome (61.5 ± 11.9 years versus 49.1 ± 12.5 years, P < 0.001). Although there were no significant differences between genders regarding symptoms, body mass index, spirometric data or daytime PaCO2 , women with obesity hypoventilation syndrome suffered significantly more from hypertension, diabetes and hypothyroidism. The prevalence of obesity hypoventilation syndrome was higher in post-menopausal (21%) compared with pre-menopausal (5.3%) women (P < 0001). HCO3 and duration of SpO2 <90% were the only independent predictors of obesity hypoventilation syndrome. In conclusion, this study reported that among subjects referred to the sleep disorders clinic for evaluation of obstructive sleep apnoea, obesity hypoventilation syndrome is more prevalent in women than men, and that women with obesity hypoventilation syndrome suffer from significantly more co-morbidities. Post-menopausal women with obstructive sleep apnoea have the highest prevalence of obesity hypoventilation syndrome.

Obesity hypoventilation syndrome in the critically ill

This article summarizes available data on the obesity hypoventilation syndrome and its pertinence to intensivists, outlines clinical and pathophysiologic aspects of the disease, discusses multidisciplinary treatments, and reviews the available literature on outcomes specific to the critically ill patient.

Obesity-hypoventilation syndrome: increased risk of death over sleep apnea syndrome

Aim

To study whether mortality and cardiovascular morbidity differ in non-invasive ventilation (NIV)-treated patients with severe obesity-hypoventilation syndrome (OHS) as compared with CPAP-treated patients with obstructive sleep apnea syndrome (OSAS), and to identify independent predictors of mortality in OHS.

Material and methods

Two retrospective cohorts of OHS and OSAS were matched 1:2 according to sex, age (±10 year) and length of time since initiation of CPAP/NIV therapy (±6 months).

Results

Three hundred and thirty subjects (110 patients with OHS and 220 patients with OSAS) were studied. Mean follow-up time was 7±4 years. The five year mortality rates were 15.5% in OHS cohort and 4.5% in OSAS cohort (p< 0.05). Patients with OHS had a 2-fold increase (OR 2; 95% CI: 1.11–3.60) in the risk of mortality and 1.86 fold (OR 1.86; 95% CI: 1.14–3.04) increased risk of having a cardiovascular event. Diabetes, baseline diurnal SaO₂ < 83%, EPAP < 7 cmH2O after titration and adherence to NIV < 4 hours independently predicted mortality in OHS.

Conclusion

Mortality of severe OHS is high and substantially worse than that of OSAS. Severe OHS should be considered a systemic disease that encompasses respiratory, metabolic and cardiovascular components that require a multimodal therapeutic approach.

A critical assessment of monitoring practices, patient deterioration, and alarm fatigue on inpatient wards: a review

Approximately forty million surgeries take place annually in the United States, many of them requiring overnight or lengthier post operative stays in the over five thousand hospitals that comprise our acute healthcare system. Leading up to this Century, it was common for most hospitalized patients and their families to believe that being surrounded by well-trained nurses and physicians assured their safety. That bubble burst with the Institute of Medicine's 1999 report: To Err Is Human, followed closely by its 2001 report: Crossing the Quality Chasm. This review article discusses unexpected, potentially lethal respiratory complications known for being difficult to detect early, especially in postoperative patients recovering on hospital general care floors (GCF). We have designed our physiologic explanations and simplified cognitive framework to give our front line clinical nurses a thorough, easy-to-recall understanding of just how these events evolve, and how to detect them early when most amenable to treatment. Our review will also discuss currently available practices in general care floor monitoring that can both improve patient safety and significantly reduce monitor associated alarm fatigue.

Effects of gas exchange on acid-base balance

This paper describes the interactions between ventilation and acid-base balance under a variety of conditions including rest, exercise, altitude, pregnancy, and various muscle, respiratory, cardiac, and renal pathologies. We introduce the physicochemical approach to assessing acid-base status and demonstrate how this approach can be used to quantify the origins of acid-base disorders using examples from the literature. The relationships between chemoreceptor and metaboreceptor control of ventilation and acid-base balance summarized here for adults, youth, and in various pathological conditions. There is a dynamic interplay between disturbances in acid-base balance, that is, exercise, that affect ventilation as well as imposed or pathological disturbances of ventilation that affect acid-base balance. Interactions between ventilation and acid-base balance are highlighted for moderate- to high-intensity exercise, altitude, induced acidosis and alkalosis, pregnancy, obesity, and some pathological conditions. In many situations, complete acid-base data are lacking, indicating a need for further research aimed at elucidating mechanistic bases for relationships between alterations in acid-base state and the ventilatory responses.

Obesity hypoventilation syndrome in obstructive sleep apnea patients in the United Arab Emirates: a retrospective cross-sectional study

Objectives

To estimate the frequency of symptoms of obesity hypoventilation syndrome (OHS) in patients with obstructive sleep apnoea (OSA) and to evaluate comorbidities associated with OHS.

Design

Retrospective study based on patients' medical records and on further sleep tests performed in the study centre during the inclusion visit.

Setting

Respiratory Care Unit and Sleep Disorder Centre of the Zayed Military Hospital United Arab Emirates.

Participants

All patients referred to the study centre for a suspicion of sleep-disordered breathing.

Main outcome measures

Prevalence of OSA and OSA + OHS and comorbidities in patients with OSA and OHS.

Results

A total of 212 adult patients participated in the study. Of these, 107 patients (50.5% [43.8–57.1% CI 95%]) fulfilled diagnostic criteria for OSA, and the majority were men (79.4%). Among patients with OSA, 18 patients (16.8% [10.8–25.1% CI 95%]) fulfilled diagnostic criteria for OHS. In this group, women were more frequently affected than men (31.8% [7/22] vs. 12.9% [11/85], respectively; p = 0.03) and tended to be older than affected men, with a mean age of 55 ± 10.6 years versus 46 ± 13 for men. After adjustment for gender, OHS was significantly associated with hypertension (OR = 3.5; p = 0.03), diabetes mellitus (OR = 4.6; p = 0.02), ischaemic heart disease (OR = 5.1; p = 0.04) and pulmonary hypertension (OR = 16.1; p = 0.001).

Conclusion

OHS is a common condition in obese patients in the UAE and is associated with an increased risk of cardiovascular comorbidities and diabetes.

Standard nonspecific therapies in the management of pulmonary arterial hypertension

Recent advances in pulmonary arterial hypertension (PAH) research have created a new era of PAH-specific therapies. Although these therapeutics have revolutionized PAH therapy, their innovation was predated by supportive but nonspecific medical therapies adapted from their use in more common cardiopulmonary diseases. These therapies include oxygen therapy, diuretics, digoxin, anticoagulation, and high-dose calcium channel blockers. Expert opinion continues to support the use of adjunct therapies based on current pathologic understandings of PAH combined with some evidence extrapolated from small studies. This article discusses why these therapies continue to play an important role in the treatment of patients with PAH.

Respiratory perioperative management of patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) has become a major public health problem in the United State and Europe. However, perioperative strategies regarding diagnostic options and management of untreated OSA remain inadequate. Preoperative screening and identification of patients with undiagnosed OSA may lead to early perioperative interventions that may alter cardiopulmonary events associated with surgery and anesthesia.(1) Hence, clinicians need to become familiar with the preoperative screening and diagnosis of OSA. Perioperative management of a patient with OSA should be modified and may include regional anesthesia and alternative analgesic techniques such as nonsteroidal anti-inflammatory drugs that may reduce the need for systemic opioids. Additionally, supplemental oxygen and continuous pulse oximetry monitoring should be utilized to maintain baseline oxygen saturation. Postoperatively patients should remain in a semi-upright position and positive pressure therapy should be used in patients with high-risk OSA.

Sleep study, respiratory mechanics, chemosensitive response and quality of life in morbidly obese patients undergoing bariatric surgery: a prospective, randomized, controlled trial

BACKGROUND

Obesity is a major public health problem in both developed and developing countries alike and leads to a series of changes in respiratory physiology. There is a strong correlation between obesity and cardiopulmonary sleep disorders. Weight loss among such patients leads to a reduction in these alterations in respiratory physiology, but clinical treatment is not effective for a long period of time. Thus, bariatric surgery is a viable option.

METHODS/DESIGN

The present study involves patients with morbid obesity (BMI of 40 kg/m2 or 35 kg/m2 to 39.9 kg/m2 with comorbidities), candidates for bariatric surgery, screened at the Santa Casa de Misericórdia Hospital in the city of Sao Paulo (Brazil). The inclusion criteria are grade III morbid obesity, an indication for bariatric surgery, agreement to participate in the study and a signed term of informed consent. The exclusion criteria are BMI above 55 kg/m2, clinically significant or unstable mental health concerns, an unrealistic postoperative target weight and/or unrealistic expectations of surgical treatment. Bariatric surgery candidates who meet the inclusion criteria will be referred to Santa Casa de Misericórdia Hospital and will be reviewed again 30, 90 and 360 days following surgery. Data collection will involve patient records, personal data collection, objective assessment of HR, BP, neck circumference, chest and abdomen, collection and analysis of clinical preoperative findings, polysomnography, pulmonary function test and a questionnaire on sleepiness.

DISCUSSION

This paper describes a randomised controlled trial of morbidly obese patients. Polysomnography, respiratory mechanics, chemosensitive response and quality of life will be assessed in patients undergoing or not undergoing bariatric surgery.

TRIAL REGISTRATION

The protocol for this study is registered with the Brazilian Registry of Clinical Trials - ReBEC (RBR-9k9hhv).

Management of diuretic treatment: a challenge in the obese patient

The obesity epidemic is a major health concern. The diagnosis of acute illness and fluid imbalance in the obese patient is complicated by a wide range of comorbidities such as cardiovascular disease, obesity hypoventilation syndrome, non-alcoholic steatohepatitis and lymphoedema. Thus, obesity warrants particularly careful clinical and biochemical assessment owing to its resemblance to fluid retention. Dosing of diuretics is difficult in these patients. The blood urea:creatinine ratio should be widely used to detect emerging cardiovascular and renal complications. This report presents an obese patient with congestive heart failure due to a myocardial infarction, who subsequently was overdosed with diuretics. His prerenal acute renal failure resolved when diuretics were stopped and the high urea:creatinine ratio was diagnostic.

Patterns of unexpected in-hospital deaths: a root cause analysis

BACKGROUND

Respiratory alarm monitoring and rapid response team alerts on hospital general floors are based on detection of simple numeric threshold breaches. Although some uncontrolled observation trials in select patient populations have been encouraging, randomized controlled trials suggest that this simplistic approach may not reduce the unexpected death rate in this complex environment. The purpose of this review is to examine the history and scientific basis for threshold alarms and to compare thresholds with the actual pathophysiologic patterns of evolving death which must be timely detected.

METHODS

The Pubmed database was searched for articles relating to methods for triggering rapid response teams and respiratory alarms and these were contrasted with the fundamental timed pathophysiologic patterns of death which evolve due to sepsis, congestive heart failure, pulmonary embolism, hypoventilation, narcotic overdose, and sleep apnea.

RESULTS

In contrast to the simplicity of the numeric threshold breach method of generating alerts, the actual patterns of evolving death are complex and do not share common features until near death. On hospital general floors, unexpected clinical instability leading to death often progresses along three distinct patterns which can be designated as Types I, II and III. Type I is a pattern comprised of hyperventilation compensated respiratory failure typical of congestive heart failure and sepsis. Here, early hyperventilation and respiratory alkalosis can conceal the onset of instability. Type II is the pattern of classic CO2 narcosis. Type III occurs only during sleep and is a pattern of ventilation and SPO2 cycling caused by instability of ventilation and/or upper airway control followed by precipitous and fatal oxygen desaturation if arousal failure is induced by narcotics and/or sedation.

CONCLUSION

The traditional threshold breach method of detecting instability on hospital wards was not scientifically derived; explaining the failure of threshold based monitoring and rapid response team activation in randomized trials. Furthermore, the thresholds themselves are arbitrary and capricious. There are three common fundamental pathophysiologic patterns of unexpected hospital death. These patterns are too complex for early detection by any unifying numeric threshold. New methods and technologies which detect and identify the actual patterns of evolving death should be investigated.