Obstructive sleep apnea in pregnancy

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1 Archives of Perinatal Medicine 19(4), , 2013 ORIGINAL PAPER Obstructive sleep apnea in pregnancy KAROLINA GRUCA-STRYJAK 1, SZCZEPAN COFTA 2, EWA WYSOCKA 3, JACEK BANASZEWSKI 4, GRZEGORZ H. BRĘBOROWICZ 1 Abstract Objective: Pregnancy is associated with many physiologic changes along with changes in breathing during sleep, placing pregnant women at risk for the development of sleep-disordered breathing. The study aims were to assess the prevalence of obstructive sleep apnea in pregnancy as well as their impact on the perinatological outcomes. Methods: We studied 101 pregnant women. They were enlisted in a prospective study divided into three parts: Part 1 questionnaire on past and present sleep disorders including Epworth Sleepiness Scale. In Part 2 all pregnant women underwent nocturnal polysomnography. In part 3-2 weeks after delivery, the patients were surveyed regarding fetal outcome and mode of delivery. Results: Obstructive sleep apnea (AHI > 5) was diagnosed in three patients, which accounted for 3% of all studied women. All of them were in the third trimester of pregnancy. The first patient course of pregnancy was uneventful. The other two patients were enrolled in the group of pregnancies complicated by preeclampsia. Two patients due to severe obstructive sleep apnea (AHI > 30) were treated by continuous positive airway pressure (CPAP). The use of CPAP led to normalization of respiratory parameters as well as to lowering blood pressure. Conclusion: Disorders of breathing during sleep contribute to the development of various diseases or they degrade the overall phenomena. Therefore, it is essential to treat not only the primary disease, but also the accompanying sleep disorders. Key words: pregnancy, sleep apnea, sleepiness, blood pressure Inroduction Sleep disturbances are common complaints during pregnancy. Sleep disturbances are typically classified as: disturbed sleep quality, short/long sleep duration, restless leg syndrome and sleep disordered breathing (SDB). Physiologic and hormonal changes occurring during pregnancy particularly concern progressive weight gain and pregnancy associated nasopharyngeal edema. These factors as well as the physical effect of the enlarging uterus decrease the functional reserve capacity and they increase the number of incidents of arousals from sleep. All of these factors may increase the likelihood of developing SDB or may magnify its effects. Although snoring, the most common symptom of obstructive sleep apnea (OSA), is common among pregnant women, the symptom is less specific for OSA than are symptoms of gasping and choking or witnessed apneas. Apnea is defined as the restriction of the flow of air through the airways of at least 10 seconds accompanied by declines in arterial oxygen saturation of at least 4%. Hypopnea is recognized when there is a reduction in the amplitude of the air passage of at least 50%, lasting longer than 10 seconds. The exponent of the severity of the above-identified episodes of breathing is apneahypopnea index [1]. Apnea and hypopnea often are combined with arousals, sleep fragmentation, reduced oxygen pressure and with an increase in the partial pressure of carbon dioxide, which is manifested by a decrease in arterial oxygen saturation. This, in turn, leads to stimulation of the sympathetic system, the activation of which causes fluctuations in heart rate and in blood pressure [2-4]. Following the recommendations of the American Academy of Sleep Medicine in 1999 for diagnosis of OSA is to determine AHI > 5, combined with excessive daytime sleepiness, and at least two of the following symptoms: 1) habitual snoring, 2) choking or gasping during sleep, 3) arousals, 4) impaired concentration, fatigue during the day [1]. The value of AHI 5-30 episodes/hour allows to identify moderate OSA, and with the AHI > 30 episodes/hour severe disease is recognized. The prevalence of OSA in pregnancy has not been systematically evaluated. It is estimated that approximately 10-24% of pregnant women in the third trimester of pregnancy suffer from sleep-related breathing disorders in the form of sleep apnea, and this proportion is significantly increased in women with preeclampsia and in 1 Department of Perinatology and Gynecology, Poznan University of Medical Sciences, Poland 2 Department of Respiratory Medicine, Alergology and Pulmonary Oncology, Poznan University of Medical Sciences, Poland 3 Chair of Chemistry and Clinical Biochemistry, Department of Clinical Biochemistry and Laboratory Medicine, Poznan University of Medical Sciences, Poland 4 Department of Otolaryngology, Poznan University of Medical Sciences, Poland

2 224 K. Gruca-Stryjak, S. Cofta, E. Wysocka, J. Banaszewski, G.H. Bręborowicz pregnancies complicated by intrauterine fetal growth restriction (IUGR) [5-10]. The exact prevalence of OSA in pregnancy is unknown, and the sleep apnea remains an unrecognized problem [10]. The study aims were to assess the prevalence of obstructive sleep apnea in pregnancy as well as their impact on the perinatological outcomes. Material and methods 1. Population The study included 101 pregnant women. The first group consisted of 68 patients in the course of normal pregnancies that were assigned to three subgroups depending on the trimester of pregnancy. The second group consisted of 33 patients in pregnancies complicated by hypertension. The women were recruited from outpatient clinical practice among colleagues of the research team and from Perinatology and Gynecology Department. All subjects provided their written informed consent for the study, which had the approval of the Local Ethics Advisory Committee. 2. Protocol Part 1 of the study included: medical and obstetric chart review, completion of sleep disorders questionnaire with the Epworth Sleepiness Scale, blood pressure assessment. In Part 2 of our study we performed full overnight polysomnography (PSG) on all 101 subjects, utilizing a recording system (Compumedics, Australia). We recorded standard electrophysiologic signals including electroencephalography, electrooculography, electromyography and electrocardiography. Furthermore, standard respiratory signals including chest and abdominal movements, nasal pressure flow heart rate and arterial oxyhemoglobin saturation (SaO 2 ) were used. The subjects were all inpatients on the antenatal ward of Department of Perinatology, and were studied in a standard hospital bed. In Part 3, two weeks following delivery, patients were surveyed by telephone regarding fetal outcome and mode of delivery. Outcomes evaluated included newborn weight, gestational weeks at the time of delivery and 1- and 5-min Apgar scores. 3. Statistical analysis For statistical analysis, SigmaStat3.5 software was used. The analysis of the results was based on the One Way ANOWA for parametric, and Kruskall-Wallis ANOVA on Ranks for non-parametric distribution in the classification of a single test with the test Turkey a multiple comparisons Holm-Sidak a or Dunn a. The value of p < 0.05 was considered statistically significant. Results Obstructive sleep apnea (AHI > 5 with excessive sleepiness ESS > 9) was detected in three patients, which accounted for 3% of all patients studied. Daytime sleepiness was assessed using the Epworth Scale (ESS). It concerned the assessment of the possibility of falling asleep in eight defined situations. Moderate sleepiness (ESS 10-14) was observed in 1 patient. The other two had severe degree of daytime sleepiness (values above 14 points). All 3 patients were habitual snorers, which means that they snore at least four nights per week. The diagnosis of OSA was made in patients in the third trimester of pregnancy. The first patient with moderate OSA (AHI 5-30) had uneventful pregnancy. The other two patients with severe OSA (AHI > 30) were classified into group of pregnancy complicated by preeclampsia (Fig. 1). Patient No. 2 was in twin pregnancy. The patient No. 3 was extremely obese and additionally diagnosed with diabetes. Clinical characteristics of this patients with polysomnographic respiratory parameters are presented in Table 1. In two patients due to severe obstructive sleep apnea (AHI> 30) the treatment with the device producing continuous positive pressure within the airways (CPAP) was introduced. The patient with AHI value = 7.1, because of the absence of clinical symptoms, did not require application of CPAP treatment. The effect of CPAP on blood pressure and selected polysomnographic respiratory parameters are presented in Table 2. Patient No. 1 gave birth at 40 weeks gestation by caesarean section (indication: decelerations in cardiotocography) of healthy male infant weighing 3360 g. Patient No. 2 gave birth at 35 weeks gestation by caesarean section (indication: decelerations in cardiotocography of the first fetus) of two healthy babies with masses of 2000 and 2110 g. In both cases, the children received 10 points the 1 st and 5 th minute in the assessment in Apgar score. Patient No. 3 at 40 weeks of pregnancy underwent physiological delivery. The newborn weighing 1790 g was evaluated in the Apgar score at 6 and 9 points respectively at 1st and 5th minutes of life. In all cases, the evaluation of the parameters of acid-base balance from umbilical vessels was within the norm.

3 Obstructive sleep apnea in pregnancy 225 Fig. 1. Fragment of the polysomnographic study of pregnant women at 31st week in pregnancy complicated by preeclampsia and OSA showing the number of sleep apnea episodes Table 1. Clinical characteristics pregnant women with OSA Patient No 1 Uncomplicated pregnancy Patient No 2 Preeclampsia Patient No 3 Preeclampsia, Gestational diabetes, Obesity Age Pregnancy-BMI (kg/m 2 ) Neck circumference (cm) Mallampati score ESS Epworth sleepiness scale Mean systolic blood pressure (mm Hg) Mean diastolic blood pressure (mm Hg) AHI apnea-hypopnea index Mean SaO 2 (%) The lowest SaO 2 (%) Table 2. Effects of treatment by means of CPAP Patient No 2 Patient No 3 before CPAP CPAP before CPAP CPAP 33 weeks of pregancy 7 day treatment of CPAP 34 weeks of pregnancy 35 weeks of pregnancy 11 day treatment of CPAP 37 weeks of pregnancy ESS Epworth sleepiness scale AHI apnea-hypopnea index Mean SaO 2 (%) The lowest SaO 2 (%) Mean systolic blood pressure (mm Hg) Mean diastolic blood pressure (mm Hg) Discussion Sleep apnea in pregnancy was first described by Joel-Cohen et al. in 1978 [11]. Most reports in the literature concerns the descriptions of single cases [12-14]. The limitations of the research concerns a small number of patients in study groups. In addition, many studies were based only on the questionnaire, and the results are not confirmed in polysomnographic study [7, 15-18]. Scientists have found that in pregnant women with hypertension habitual snoring and sleep apnea were

4 226 K. Gruca-Stryjak, S. Cofta, E. Wysocka, J. Banaszewski, G.H. Bręborowicz diagnosed more often [7, 15, 19, 20]. It is significant that the detected respiratory problems in women with preeclampsia are mild and in the general population could be considered as negligible. The episodes of apnea, hypopnea or episodes of desaturation that could meet the criteria for the diagnosis of obstructive sleep apnea are observed very rarely in preeclamptic patients. However, these seemingly minor disturbance of air flow in upper airway contribute significantly to the increase in blood pressure during sleep which is especially important in the case of preeclampsia [21-23]. This means, that the increase in blood pressure in these cases is not a consequence of the desaturation episodes and followed hypoxia, but is associated with the vascular complications of SDB. Currently, the most popular hypothesis linking pregnancy-induced hypertension with sleep disorders relates to the partial obstruction within the upper airway during sleep. This, in turn, results in a relative increase in pco 2 concentration, which stimulates sympathetic system. In the case of preeclampsia damaged endothelium is hypersensitive on this stimulation and the response is exacerbated, leading to generalized vasospasm [21, 22, 24]. The effectiveness of the CPAP in patients with preeclampsia confirms the existence of the above presented relationship. In addition, it may result in the prevention of growth of pco 2, which is one of the best-known vasoconstricting factors [23]. However, it must be emphasized that sleep disordered breathing in pregnant women may develop independently of the development of hypertension [22, 25, 26]. This has been confirmed in our study. We found that the prevalence of obstructive sleep apnea in the group of physiological pregnancies was 1.5% and it was a mild form of OSA (AHI< 30). While in the group of pregnancies complicated by hypertension the incidence of OSA was 6% and it were severe obstructive sleep syndromes with the values of the AHI above 70. These problems also contributed to the increase in blood pressure during the course of preeclampsia. Breathing disorders during sleep also have an adverse effect on the health of pregnant women and their effects can be distant. They not only caused deterioration in the quality of life, but most of all they influences on life duration. Mortality in the course of obstructive sleep apnea refers to sudden death during sleep, to the development of chronic diseases, especially cardiovascular and to traffic accidents and accidents at work, which are caused by excessive daytime sleepiness. In the literature we can find several case reports of deaths during sleep that occurred during polysomnography examination. The first case involved a 52-year-old obese women (BMI 67.3 kg/m 2 ). After the subsequent obstructive sleep apnea there has been no return of spontaneous ventilation, resulting in cardiac arrest. An autopsy showed no other cause of death [27]. The second case also concerned the obese (BMI 60.2 kg/m 2 ) woman aged 60 years with heart failure and severe OSA [28]. Stopping of breathing is one of the mechanisms of sudden death in sleep. the others concerns acute cardiovascular events and cardiac arrhythmias. Particularly serious are the ventricular arrhythmias. High heart rate variability due to firstly vagus nerve stimulation (apnea-bradycardia) and secondly parasympathetic activation (back-ventilation tachycardia) predispose to them. Imposition of acute hemodynamic effects on chronic, present in OSA, risk factors may be another mechanism of sudden cardiac arrest in this population. Severe bradycardia or tachycardia may reduce cardiac output and reduce perfusion of the central nervous system. Researchers have found that during obstructive sleep apnea is a significant decrease in cerebral blood flow. Moreover, it has been demonstrated that cerebrovascular sensitivity to hypercapnia is reduced in this group of patient [29, 30]. This suggests that OSA may be an important risk factor for cerebrovascular events. Obstructive sleep apnea causes a number of metabolic and endocrine system implications. Scientific studies clearly indicate that OSA is an integral component of the metabolic syndrome, as well as visceral obesity, hypertension and impaired glucose and lipid metabolism [31, 32]. Has also been shown, that the incidence of snoring and sleep apnea contributes to the development of diabetes, increased platelet aggregation and reduce plasma fibrinolytic activity [33, 34]. A retrospective study conducted by He et al. related to 5-year follow-up of deaths among patients with OSA [35]. The study demonstrated that AHI has a high predictive value in the assessment of mortality in patients with untreated obstructive sleep apnea. The value of AHI > 20 increased mortality of 37% in 8 years observation. All the above presented information are very important, particularly with regard to the two described patients with severe obstructive sleep apnea. Despite their young age, both patients are at high risk for cardiovascular complications. In the second case, due to extreme obesity with co-morbidities problems (pregnancy induced hypertension, gestational diabetes) we made diagnosis of metabolic syndrome. In both patients, due to concomitant with preeclampsia disordered breathing during

5 Obstructive sleep apnea in pregnancy 227 sleep can cause excessive release of endothelin, catecholamines, and vascular endothelial growth factor VEGF that the mitogenic effect can lead to preservation of hypertension [36]. Therefore, it is very important to further diagnosis and treatment of these patients in order to prevent occurrence of cardiovascular complications, because they are exposed to them to a very large extend. Basing on the guidelines of treatment for obstructive sleep apnea in the general population Pien and Schwab created recommendations for pregnant women [37]. Treatment of choice for symptomatic pregnant women diagnosed with moderate OSA (AHI 5-30 episodes/hour) or with episodes of desaturation below 90% and in pregnant women with severe OSA (AHI > 30 episodes/hour) is breathing at a constant positive pressure airway CPAP. Blyton and colleagues in their study found that the use of CPAP in pregnancy complicated by preeclampsia caused an increase in cardiac output due to a reduction in peripheral resistance [38]. A study conducted by Guilleminault et al. in 2004, including 12 women, who have included treatment with CPAP, also confirmed these findings and pointed to the fact that this method is safe and well tolerated by patients [39]. Reports related to the use of CPAP during pregnancy are not numerous, but none of the work has shown its harmful effects on the fetus [12, 14, 40, 41]. Guilleminault et al. in 2007 conducted a prospective study of early application of CPAP and their impact on perinatological outcomes. Treatment with CPAP was applied in 12 pregnant women in the first trimester of pregnancy with risk factors for the development of preeclampsia. This made it possible to alleviate breathing problems during sleep, but it was insufficient to avoid adverse results in the mother and the fetus [42]. However, in a randomized study conducted by Poyares'a and colleagues, they compared treatment with CPAP to standard medical treatment [43]. It was noted that the combination of these two forms of therapy during early pregnancy improved blood pressure control, without the need to increase antihypertensive treatment. However, the results on the state of the newborn were similar in both groups. Skilton, et al. observed a reduction in the number of fetal movements in women with preeclampsia compared to the control group (319 vs. 689, p < ), and this number was significantly increased after introducing CPAP treatment (p < ) [44]. In our study, after diagnosis of severe obstructive sleep apnea in two patients, the CPAP therapy was introduced. The use of this type of treatment allowed, as well as normalization of respiratory parameters in polysomnography, to lower blood pressure without changes in their drug therapy. We are aware that our study have several limitation. 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