Sleep Apnea in Moderate-Severe Obese Patients

Abstract

Obesity induces multiple physiologic changes at the respiratory and circulatory systems level. A study was developed to identify symptoms and signs able to discriminate subjects at high risk of obstructive sleep apnea (OSA) and to evaluate the presence of OSA in a population of obese patients referred to the Clinical Nutrition Service of the Luigi Sacco Hospital for weight loss therapy. Twenty-seven obese patients (14 males, 13 females) without neurologic, cardiac, and lung diseases were measured for height, weight, neck, waist, and hip circumference; a sample of venous blood was taken for hematological data; and were given a pulmonary function test, hemogasanalysis, and full-night polysomnography. Statistical analysis were performed using paired and unpaired StudentOs t test, PearsonOs chi square, and Spearmann Rank correlation; the significance level was set at p<0.05. The results showed hemotological values in the normal range and pulmonary function findings were not different from predicted, but expiratory reserve volume (ERV), as expected in obese subjects, was significantly reduced (p<0.001). Waist, hip, and neck circumference, and waist/hip ratio were 114 +/-14, 118 +/-12, 44 +/-4, and 0.96 +/-0.4 cm respectively. An apnea-hypopnea index (AHI) cutoff value of <15 was used to classify the patients as suffering from OSA: 15 patients (12 males, 3 females, age in years 55 +/-12, body mass index (BMI) kg/m(2) 37 +/-6, AHI 30 +/-12) were OSA and 12 patients were non OSA (2 males, 10 females, age in years 49 +/-20, BMI kg/m(2) 35 +/-2, AHI 3 +/-2). PaO2 and pH were lower and PaCO2 higher in OSA (p<0.05, p<0.01, p<0.05, respectively). Red blood cells (RBC), Hb, and neck circumference were increased in OSA (p<0.05). In OSA patients, S3%, S4% of total sleep time, SaO2% mean of nadir were reduced (p<0.001), and DEF increased (p<0.0001). In obese patients, AHI was correlated with neck circumference (r = 0.74, p<0.0001) and waist/hip ratio (r = 0.48. p<0.01). DEF was correlated with RBC, Hb, Htc% (r = 0.82, 0.71, 0.66, p<0.001). SaO2;% mean of nadir was significantly related to RBC, Hb, and Htc% (r = 0.44, 0.40, p<0.05, respectively). Our data showed a prevalence of OSA in 55% of the obese patients. A significant correlation exists between RBC, Hb, Htc%, with desaturation events frequency (DEF) and SaO2% of nadir indicating that transient, episodic desaturation during sleep is linked to a moderate increase of RBC and Hb found in obese patients with OSA, in contrast to obese, nonOSA patients. The most important result of the present study was the determination that classical symptoms and signs of OSA, such as male gender, neck circumference, waist/hip ratio, RBC, and Hb at the upper limit of normal, are simple inexpensive screening tools, and useful predictors of sleep-disordered breathing and discriminate the individuals with higher risk of OSA.

A comparative study on the clinical and polysomnographic pattern of obstructive sleep apnea among obese and non-obese subjects

“…[20–24] The present study has also shown similar findings and strikingly the minimal oxygen saturation was well below 90% in both the groups. The etiology of OSA in obese has been linked with anatomic alterations that predisposes to upper airway obstruction during sleep.…”

Increased central adiposity in morbidly obese patients with obstructive sleep apnoea

“…This analysis showed increased deposition of adipose tissue in central regions in morbidly obese individuals with OSA as compared with those without this respiratory disorder. Our results are consistent with other reports in the general population that central adiposity is associated with an increased likelihood of developing sleep apnoea 9–11 . However, our data are unique and show that even among the morbidly obese (BMI >40 kg/m 2 ), these patterns remain.…”

Sindrom obstruktivnykh apnoe vo sne: sovremennye predstavleniya i rol'

“…T. Young и со ав то ры (1993) по ка за ли, что уве ли че ние ИМТ на од но стан дарт ное от кло не ние при во дит к че ты рёх крат но му уве ли че нию ри с ка по па да ния в груп пу боль ных СО АС [35]. Сре ди боль ных ожи ре ни ем пред став лен ность СО АС зна читель но вы ше, чем в це лом в по пу ля ции -55%, по данным M. Sergi и со ав то ров (1999) [26].…”

“…R. Grunstein и со ав то ры до ка зы ва ют, что аб до ми наль ный тип ожи ре ния пред рас по ла га ет к разви тию об ст рук тив ных ап ноэ во сне, при чем он яв ля ется не за ви си мым фак то ром уве ли че ния чис ла ды хатель ных рас ст ройств [12]. D. Revicki и R. Israel (1986) для пре дик ции зна че ний ИДР под чёр ки ва ют важность та ко го по ка за те ля, как ок руж ность та лии [22]; M. Sergi и со ав то ры (1999) счи та ют бо лее ин фор матив ным от но ше ние объ е ма та лии к объ е му бе дер (ОТ/ОБ) [26]. Пред по ла га ет ся, что аб до ми наль ный тип ожи ре ния спо соб ст ву ет раз ви тию об ст рук тив ных ап ноэ за счёт сни же ния лё гоч ных ды ха тель ных объ ёмов, что при во дит, с од ной сто ро ны, к хро ни че с кой ги по ксе мии и на ру ше нию хе мо ре цеп тор ной чув ст витель но с ти, с дру гой -к на ру ше нию ре флек тор ной акти ва ции мышц ВДП во вре мя ды ха тель но го цик ла.…”