Hypoventilation syndromes

Brazilian Thoracic Association Consensus on Sleep-disordered Breathing

Sleep is essential for the proper functioning of all individuals. Sleep-disordered breathing can occur at any age and is a common reason for medical visits. The objective of this consensus is to update knowledge about the main causes of sleep-disordered breathing in adult and pediatric populations, with an emphasis on obstructive sleep apnea. Obstructive sleep apnea is an extremely prevalent but often underdiagnosed disease. It is often accompanied by comorbidities, notably cardiovascular, metabolic, and neurocognitive disorders, which have a significant impact on quality of life and mortality rates. Therefore, to create this consensus, the Sleep-Disordered Breathing Department of the Brazilian Thoracic Association brought together 14 experts with recognized, proven experience in 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.

[Interpretation of acid-base disorders]

Keeping blood pH levels stable within narrow limits is prerequisite for maintaining normal body function. Disruptions of this equilibrium can occur for a variety of reasons and may result in life-threatening conditions. Therefore, the identification and the interpretation of acid-base disorders are of great importance in emergency medicine. The same applies to intensive care as well as to almost all areas of internal medicine. In this article, we provide a practical overview of all relevant acid-base disorders that are due to both metabolic and respiratory disturbances. In addition, it shows how they can be diagnosed in everyday clinical practice by applying the simplified Stewart Approach.

Sleep in chronic respiratory disease: COPD and hypoventilation disorders

COPD and obstructive sleep apnoea (OSA) are highly prevalent and different clinical COPD phenotypes that influence the likelihood of comorbid OSA. The increased lung volumes and low body mass index (BMI) associated with the predominant emphysema phenotype protects against OSA whereas the peripheral oedema and higher BMI often associated with the predominant chronic bronchitis phenotype promote OSA. The diagnosis of OSA in COPD patients requires clinical awareness and screening questionnaires which may help identify patients for overnight study. Management of OSA-COPD overlap patients differs from COPD alone and the survival of overlap patients treated with nocturnal positive airway pressure is superior to those untreated. Sleep-related hypoventilation is common in neuromuscular disease and skeletal disorders because of the effects of normal sleep on ventilation and additional challenges imposed by the underlying disorders. Hypoventilation is first seen during rapid eye movement (REM) sleep before progressing to involve non-REM sleep and wakefulness. Clinical presentation is nonspecific and daytime respiratory function measures poorly predict nocturnal hypoventilation. Monitoring of respiration and carbon dioxide levels during sleep should be incorporated in the evaluation of high-risk patient populations and treatment with noninvasive ventilation improves outcomes.

Neuropulmonology

Neuropulmonology refers to the complex interconnection between the central nervous system and the respiratory system. Neurologic injury includes traumatic brain injury, hemorrhage, stroke, and seizures, and in each there are far-reaching effects that can result in pulmonary dysfunction. Systemic changes can induce impairment of pulmonary function due to changes in the core structure and function of the lung. The conditions and disorders that often occur in these patients include aspiration pneumonia, neurogenic pulmonary edema, and acute respiratory distress syndrome, but also several abnormal respiratory patterns and sleep-disordered breathing. Lung infections, pulmonary edema - neurogenic or cardiogenic - and pulmonary embolus all are a serious barrier to recovery and can have significant effects on outcomes such as hospital course, prognosis, and mortality. This review presents the spectrum of pulmonary abnormalities seen in neurocritical care.

Domiciliary noninvasive positive airway pressure therapy in children

There has been a dramatic increase in the past few decades in the number of children receiving noninvasive positive airway pressure (PAP) therapy at home. Although PAP therapy was first prescribed for children with obstructive sleep apnea, the indications have rapidly widened to include treatment for central hypoventilation syndromes, neuromuscular and chest wall disorders as well as primary respiratory diseases. Given the rapidly expanding use of PAP therapy in children, pediatric pulmonologists need to be familiar with the indications, technical and safety considerations as well as potential complications and challenges that may arise when caring for children using PAP therapy. This review article covers the definition of PAP therapy, modes, interfaces, devices, indications, contraindications, suggested settings, complications as well as the factors influencing the adherence.

Current perspectives for management of acute respiratory insufficiency in premature infants with acute respiratory syndrome

Current perspectives for management of acute respiratory insufficiency in premature infants with acute respiratory syndrome and the pathology of acute respiratory insufficiency in the preterm infant, including the current therapy modalities on disposition are presented. Since the therapeutical challenge and primary clinical goal are to normalize ventilation ratio and lung perfusion, when respiratory insufficiency occurs, it is very important to introduce the respiratory support as soon possible, in order to reduce development of pulmonary cyanosis and edema, and intrapulmonary or intracardial shunts. A characteristic respiratory instability that reflects through fluctuations in gas exchange and ventilation is often present in premature infants. Adapting the respiratory support on a continuous basis to the infant's needs is challenging and not always effective. Although a large number of ventilation strategies for the neonate are available, there is a need for additional consensus on management of acute respiratory distress syndrome in pediatric population lately redefined by Berlin definition criteria, in order to efficiently apply various modes of respiratory support in daily pediatrician clinical use.

Acute and chronic respiratory failure

Respiratory failure (RF) can be attributed to a plethora of neuromuscular diseases (NMDs) and manifests clinically in a multitude of overt or more subtle ways. The basic principles of pathophysiology, diagnosis and treatment of neurologic diseases and of RF apply concomitantly to this subset of patients. Various entities should be approached according to the latest evidence-based recommendations. Treatment follows the natural disease progression, from minimal respiratory assistance to mechanical ventilation (MV). A comprehensive treatment plan has to be formulated that takes into consideration the patient's wishes.

Aerodynamic profiles of women with muscle tension dysphonia/aphonia

PURPOSE

In this study, the authors aimed to (a) determine whether phonatory airflows and estimated subglottal pressures (est-Psub) for women with primary muscle tension dysphonia/aphonia (MTD/A) differ from those for healthy speakers; (b) identify different aerodynamic profile patterns within the MTD/A subject group; and (c) determine whether results suggest new understanding of pathogenesis in MTD/A.

METHOD

Retrospective review of aerodynamic data collected from 90 women at the time of primary MTD/A diagnosis.

RESULTS

Aerodynamic profiles were significantly different for women with MTD/A as compared with healthy speakers. Five distinct profiles were identified: (a) normal flow, normal est-Psub; (b) high flow, high est-Psub; (c) low flow, normal est-Psub; (d) normal flow, high est-Psub; and (e) high flow, normal est-Psub.

CONCLUSIONS

This study is the first to identify distinct subgroups of aerodynamic profiles in women with MTD/A and to quantitatively identify a clinical phenomenon sometimes described in association with it-"breath holding"-that is shown by low airflow with normal est-Psub. Results were consistent with clinical claims that diverse respiratory and laryngeal functions may underlie phonatory patterns associated with MTD/A. One potential mechanism, based in psychobiological theory, is introduced to explain some of the variability in aerodynamic profiles of women with MTD/A.

Factors associated with noninvasive ventilation response in the first day of therapy in patients with hypercapnic respiratory failure

BACKGROUND AND AIM:

Noninvasive ventilation (NIV) decreases mechanical ventilation indication in the early period of acute hypercapnic respiratory failure (AHcRF) and factors for success have been studied well. But, less is known about the factors influencing the NIV response in the subacute period. This study was aimed to determine the factors influencing the reduction of PaCO₂ levels within first 24 hours of therapy.

METHODS:

NIV response was defined as reduction of PaCO₂ level below 50 mmHg within first 24 hours. Patients with AHcRF, treated with NIV, were divided into 2 groups according to this criterion; group 1 as the nonresponsive, group 2 as the responsive. The differences in NIV methods and characteristics of the two groups were evaluated and compared in this retrospective study.

RESULTS:

A total of 100 patients were included in the study; 66 of them in group 1 and 34 in group 2. No significant differences were identified between the length of NIV application and intensive care unit (ICU) stay, intubation and mortality rates, across the groups. Ninety-one percent of the patients in group 2 had received all night long NIV therapy; this was just 74% in group 1 (P=0.036). Results of multivariate analysis showed that while nocturnal application was significantly associated with better response, prior home ventilation and requirement of higher pressure support (PS) levels significantly and independently associated with poorer response to NIV therapy.

CONCLUSION:

In patients with AHcRF, all night long use of NIV may accelerate healing by improving PaCO₂ reduction within the first 24 hours. A rapid response in PaCO₂ levels should not be expected in patients requiring higher PS levels and using prior home ventilation.

Força muscular respiratória de mulheres obesas mórbidas e eutróficas

A obesidade mórbida é uma condição clínica que afeta a capacidade funcional, sendo a musculatura respiratória igualmente comprometida. Objetivou-se avaliar a força muscular inspiratória e expiratória de mulheres obesas mórbidas (MO) e eutróficas (ME). Estudo transversal com amostra composta por 21 mulheres (14 MO e 7 ME), pareadas pela idade e altura. A avaliação da força muscular inspiratória e expiratória foi realizada por meio da verificação das pressões inspiratória e expiratória por manovacuometria. Quando comparadas as pressões respiratórias estáticas máximas obtidas com os valores preditos para ME e MO, constata-se que as do primeiro grupo apresentam valores de P Imáx=119,14±1,9 cmH2O (152% do predito) e P Emáx=141,1±10,2 cmH2O (98,5% do predito) dentro dos limites de normalidade ou acima, enquanto no grupo de obesas mórbidas os valores de P Imáx=66±18,7 cmH2O (84,3% do predito) e P Emáx=78,4±14,2 cmH2O (54,3% do predito) foram inferiores aos preditos. Comparando-se as pressões respiratórias estáticas máximas obtidas de MO com ME, observa-se diferença significativa tanto para os valores de P Imáx (66±18,7 versus 119±1,9 cmH2O) como P Emáx (78,4±14,2 versus 141,14±10,20) com significância estatística de 0,001. Conclui-se que a força muscular respiratória é marcadamente diminuída em MO, quando comparadas a ME.