Cardiorespiratory consequences of sleep apnoea syndrome in patients with massive obesity

Abstract

aaSleep apnoea syndrome (SAS) has been reported to be associated with excess mortality [1,2] and a wide range of cardiac and respiratory sequelae [3][4][5]: daytime alveolar hypoventilation, pulmonary arterial hypertension, systemic arterial hypertension, left ventricular hypertrophy and dysfunction, cardiac arrhythmias and ischaemic heart disease. However, conflicting data have been published on the cardiorespiratory consequences of SAS. This might be due to the fact that most studies did not take sufficient account of the potential effects of confounding variables, such as age, smoking, and obesity [6]. Obesity is a major confounding factor as it is strongly associated with SAS [7,8], and may yield the same cardiorespiratory complications as SAS. Therefore, observing cardiac and respiratory abnormalities in an obese patient with SAS does not necessarily imply a causal association between nocturnal apnoeas and cardiorespiratory morbidity.Another confounding factor is the association of chronic obstructive pulmonary disease (COPD), which may explain certain conflicting results on the role of SAS in the development of daytime alveolar hypoventilation and pulmonary arterial hypertension [9][10][11].The aim of the present study was to assess the cardiorespiratory consequences of SAS by comparing the results of a comprehensive cardiorespiratory evaluation in apnoeic and nonapnoeic patients with a similar degree of obesity, i.e. massive obesity and without COPD. This study investigated the role of SAS in the development of daytime alveolar hypoventilation, pulmonary arterial hypertension, systemic arterial hypertension, left ventricular dysfunction, left ventricular hypertrophy and dilatation, cardiac arrhythmias and coronary artery disease. Patients and methods Study populationThe study population included morbidly obese patients admitted consecutively over a 3 yr period to the Nutrition department of Hôtel-Dieu Hospital for an extensive Nocturnal apnoeas in massive obesity may thus be associated with moderate daytime hypoxaemia, mild pulmonary arterial hypertension and moderate left ventricular hypertrophy, but not with severe cardiorespiratory complications.

Pulmonary haemodynamics in patients with OSAS or an overlap syndrome

“…The differences in the lifestyle, extreme obesity [7] or genetic predisposition to excessive hypoxic pulmonary vasoconstriction [21] may also contribute to development of PH in some patients with OSAS.…”

“…Results of majority of studies have suggested that pulmonary hypertension develops in OSAS patients only when signs of COPD are present or they suffer from extreme obesity [3][4][5][6][7]. However, other authors found pulmonary hypertension also in patients with pure OSAS or those patients who are not extremely obese [8][9][10].…”

A syndrome of sleep apnea in morbid obesity

“…The presence of SAS in MO induces greater diurnal hypoxemia [32]. The FRC has shown a negative correlation with the ODI [33]. As for diffusion, an increase in DLCO and KCO has been reported in the obese with SAS, which correlates more with BMI than with SAS itself [35].…”

Desafios no manuseio peri-operatório de pacientes obesos mórbidos: como prevenir complicações

“…Um aumento do volume sangüíneo e do fluxo pulmonar predispõe os indivíduos obesos à hipertensão pulmonar, que pode ser acentuada pela vasoconstrição pulmonar relacionada a alterações pulmonares que causam hipoxemia. A síndrome da apnéia do sono, que está fortemente associada à obesidade, pode acentuar a hipoxemia em certos períodos e agravar a hipertensão pulmonar 16 . Falência cardíaca ocorre com freqüência em pacientes com obesidade grave e parece ser uma importante causa de morte 15 .…”

“…Increased blood volume and pulmonary flow predisposes obese individuals to pulmonary hypertension, which may be worsened by pulmonary vasoconstriction related to pulmonary changes which lead to hypoxemia. Sleep apnea syndrome, which is strongly related to obesity, may worsen hypoxemia during certain periods thus aggravating pulmonary hypertension 16 . Heart failure is frequent in severely obese patients and seems to be a major cause of mortality 15 .…”