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Biomedical subjects

C E Sullivan

Publications and source records attributed to C E Sullivan.

At least 73 records · Page 4Linked to original sources
PubMed1995

Obstructive sleep apnea: the use of nasal CPAP in 80 children.

This is a retrospective review of children 15 years of age or younger, who underwent overnight sleep studies between 1980 and 1993. All were diagnosed and treated for obstructive sleep apnea (OSA). Overnight studies were performed for OSA in 413 children. One hundred seventy-five (42.4%) children were treated with adenotonsillectomy and 80 (19.4%) with nasal mask continuous positive airway pressure (nCPAP). The proportion of male children was greater than expected in both the entire study group (69%, p < 0.001) and in those treated with nCPAP for OSA (71% p < 0.001). There was no significant difference between the mean age of the children treated with nCPAP (5.7 +/- 0.5 yr) and the entire group studied (5.04 +/- 0.21 yr). A greater proportion of the children who received nCPAP therapy had a congenital syndrome or malformation than in the group with OSA as a whole; 27.7% of children assessed for OSA were affected, and 53% of those children with OSA who received treatment with nCPAP (p < 0.001). Therapy with nCPAP (mean duration 15 +/- 3 mo, mean pressure 7.9 cm H2O) eliminated the signs of OSA in 72 children (90%). Respiratory disturbance index fell from a mean of 27.3 +/- 20.2 to 2.55 +/- 2.74 (p < 0.001). Eight of 32 children who underwent pressure determination studies could not tolerate nCPAP above an upper limit because of hypoventilation or frequent central apneas. Nevertheless, we conclude that nCPAP is an effective and generally well-tolerated therapy for treatment of OSA in infants and children.

Adenoidectomy↗
PubMed1995

Sleep apnea in Marfan's syndrome. Increased upper airway collapsibility during sleep.

Marfan's syndrome is a hereditary disorder characterized by a defect in connective tissue, resulting in tissue laxity. It is associated with a high prevalence of obstructive sleep apnea (OSA). The aim of this study was to determine whether excessive upper airway collapsibility during sleep is an important pathophysiologic factor predisposing these individuals to OSA. We measured upper airway closing pressures (UACP) during sleep in 12 patients with Marfan's syndrome and 6 age-, and height-, and weight-matched control subjects. Ten of the patients had OSA, defined as an apnea/hypopnea index > 5. All patients with Marfan's syndrome, including the two patients without OSA, demonstrated increased upper airway collapsibility during sleep, with a mean UACP of -2.5 +/- 0.5 cm H2O during slow-wave sleep (SWS). In contrast, only two control subjects demonstrated upper airway closure. However, this was at significantly higher suction pressures, with a mean UACP of -5.6 +/- 0.4 cm H2O during SWS (p < 0.005). These data suggest that patients with Marfan's syndrome have abnormally increased upper airway collapsibility during sleep. It is possible that this is related to the characteristic connective tissue defect of this disorder.

Adult↗
PubMed1995

Pulmonary hypertension in obstructive sleep apnoea.

To determine the frequency and correlates of pulmonary hypertension in sleep-disordered breathing, pulmonary artery pressure, lung function and arterial blood gases were measured in 100 consecutive patients with obstructive sleep apnoea (OSA) (respiratory disturbance index (RDI) of > 20 episodes.h-1). Twenty six of the patients had significant chronic airflow limitation (CAL). Overall, 42% of patients had awake pulmonary artery pressure > 20 mmHg. Patients with pulmonary hypertension were older, had higher arterial carbon dioxide tension (PaCO2), lower arterial oxygen tension (PaO2) and lower forced expiratory volume in one second (FEV1) values compared with normotensive patients. Pao2, PaCO2 and FEV1 were correlated with the levels of pulmonary artery pressure (correlation coefficient (r2) 0.50, 0.46 and 0.49, respectively). These three factors combined could explain 33% of the variability in pulmonary artery pressure. Six patients had pulmonary hypertension despite a PaO2 in excess of 10.7 kPa (80 mmHg). We conclude that pulmonary hypertension is common in patients with moderate and severe sleep apnoea, especially those with coexisting chronic airflow limitation. The presence of daytime hypoxaemia is not a prerequisite in the development of pulmonary hypertension in these patients.

Case-Control Studies↗
PubMed1994

Effect of octreotide, a somatostatin analog, on sleep apnea in patients with acromegaly.

OBJECTIVE: To determine the effects of octreotide, a somatostatin analog, on the severity of sleep apnea and on growth hormone levels in patients with acromegaly. DESIGN: Open-label, prospective study. SETTING: Tertiary referral hospital. PATIENTS: 19 patients with active acromegaly. INTERVENTION: Octreotide in a 6-month, stepwise incremental dosage. MEASUREMENTS: Sleep studies and indices of hormonal activity (levels of insulin-like growth factor 1 [IGF-1] and growth hormone). RESULTS: A 50% decrease occurred in the respiratory disturbance index (baseline compared with 6 months, 39 events/h compared with 19 events/h; P = 0.0002), and a 40% decrease occurred in total apnea time (27.6% of total sleep time compared with 15.1%; P = 0.001). Indices of oxygen desaturation, sleep quality, and subjective sleepiness improved after 6 months of octreotide. A parallel decrease was noted in mean levels of growth hormone (40.0 micrograms/L compared with 9.1 micrograms/L; P = 0.003) and IGF-1 (107 nmol/L compared with 47 nmol/L; P = 0.0001). However, no correlation was noted between the decrease in the total amount of sleep time spent in apnea and the decrease in growth hormone levels (rho = -0.35; P > 0.2). The residual respiratory disturbance index after 6 months of treatment was similar in patients who improved, regardless of whether or not biochemical remission (IGF-1 < 35 nmol/L) occurred. CONCLUSIONS: Improvement in indices of sleep apnea severity occurs in association with octreotide treatment in patients with sleep apnea and acromegaly. However, sleep apnea may either persist despite normalization of growth hormone levels or may improve markedly even if there is only partial biochemical remission.

Acromegaly↗
PubMed1994

Effect of short-term hormone replacement in the treatment of obstructive sleep apnoea in postmenopausal women.

BACKGROUND: Women appear to be increasingly susceptible to snoring and sleep disordered breathing after the menopause. This observation, coupled with the considerable sex difference in sleep apnoea, may be explained on the basis of a protective effect of female hormones. This study was carried out to determine whether hormone replacement therapy has a role in the management of obstructive sleep apnoea in postmenopausal women. METHODS: The effect of short-term (mean (SE) 50 (3) days) hormone replacement therapy with either oestrogen alone or in combination with progesterone on sleep disordered breathing was investigated in 15 postmenopausal women with moderate obstructive sleep apnoea. The effect of treatment on the ventilatory response to hypoxia and hypercapnia was assessed in 10 patients. RESULTS: There was no reduction in the clinical severity of obstructive sleep apnoea after hormone treatment despite an increase in the serum oestrogen level from 172 (23) to 322 (33) pmol/l. There was a small but clinically insignificant reduction in the apnoea/hypopnoea index during REM sleep from 58 (6) to 47 (7). There was no difference in response between the oestrogen only group and the oestrogen plus progesterone group. Hypercapnic ventilatory responsiveness did not change with hormone treatment, but an change with hormone treatment, but an increase in hypoxic ventilatory responsiveness was observed. CONCLUSIONS: These data indicate that short-term hormone replacement is unlikely to have an effective role in the clinical management of postmenopausal women with obstructive sleep apnoea. The observed reduction in the apnoea/hypopnoea index during REM sleep, however, suggests that longer term treatment, or the use of higher doses, may have an effect.

Drug Therapy, Combination↗
PubMed1994

Effect of testosterone administration on upper airway collapsibility during sleep.

Testosterone is thought to play a role in the pathogenesis of obstructive sleep apnea (OSA), but the mechanism is unclear. We present a case in which testosterone administration induced or exacerbated OSA in a 13-year-old male. We demonstrated that exacerbation of OSA by testosterone was associated with an increase in upper airway collapsibility during sleep, and that this improved after cessation of hormone administration. Our data strongly suggest that the mechanism by which testosterone administration may induce or exacerbate OSA is through an influence on neuromuscular control of upper airway patency during sleep.

Adolescent↗
PubMed1994

Central sleep apnea is associated with increased ventilatory response to carbon dioxide and hypersecretion of growth hormone in patients with acromegaly.

Although obstructive sleep apnea (OSA) occurs commonly in acromegaly, we have recently reported an unexpectedly high prevalence of central sleep apnea (CSA) in these patients. Acromegalic patients with CSA have increased growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels compared with their counterparts with OSA. Studies in animals, normal humans, and patients with sleep apnea have suggested that CSA is associated with increased gain of the respiratory control system. To examine the relationship between sleep apnea, respiratory control, and hormonal activity in acromegaly, we performed sleep studies and examined ventilatory responses to hypoxia at resting CO2 (HVR) and 8 mm Hg above resting CO2 (HHVR) and hypercapnia (HCVR) in 54 patients with acromegaly who also underwent detailed endocrine evaluation. Patients with CSA (n = 11) had higher HCVR (3.47 +/- 0.57 L/min/mm Hg) than did patients with obstructive sleep apnea (OSA) (1.86 +/- 0.19, n = 33) and patients without sleep apnea (1.77 +/- 0.21, n = 10). Measures of ventilatory control were all correlated with the mean of 12 hourly GH concentrations, but only HCVR was correlated with IGF-1 levels. Multiple linear regression analysis revealed that HCVR, HHVR, and IGF-1 could explain 39% of the variability in the degree of CSA in acromegalic patients with sleep apnea. We conclude that increased ventilatory responsiveness and elevated hormonal parameters of disease activity both contribute to the pathogenesis of central sleep apnea in acromegaly.

Acromegaly↗
PubMed1994

Obstructive sleep apnea in obese noninsulin-dependent diabetic patients: effect of continuous positive airway pressure treatment on insulin responsiveness.

Patients with noninsulin-dependent diabetes mellitus (NIDDM) are often obese and frequently complain of tiredness. These features are also characteristically seen in patients with obstructive sleep apnea (OSA). Therefore, it was the aim of this study to assess the prevalence of OSA among a group of obese NIDDM patients who have some clinical features of OSA. The effect of reversal of OSA by nasal continuous positive airway pressure (CPAP) treatment on insulin responsiveness was also investigated. From a population of 179 NIDDM patients with a body mass index (BMI) greater than 35 kg/m2, we performed ambulatory sleep monitoring on 31 (15 males and 16 females) who admitted to either heavy snoring or excessive sleepiness. Results were reviewed by a sleep physician blinded to the clinical status of the patients, and 22 (70%) were found to have moderate or severe OSA, with mean oxygen desaturation indexes of 10.3 +/- 5.3 and 30.7 +/- 13.2 episodes/h, respectively. A subgroup of 10 patients (seven males and three females) with a mean BMI of 42.7 +/- 4.3 kg/m2 was treated with nightly CPAP for 4 months. These subjects all had significant OSA, with frequent obstructive apneas (mean, 47 +/- 31.6 episodes/h) and oxygen desaturation (mean minimum O2 saturation, 74 +/- 9.5%), as determined by polysomnography. One patient was excluded from analysis because of infrequent use of CPAP. Insulin responsiveness in terms of glucose disposal measured by hyperinsulinemic euglycemic clamps improved from 11.4 +/- 6.2 to 15.1 +/- 4.6 mumol/kg.min (P < 0.05) during CPAP treatment. These results indicate that OSA occurs commonly in obese NIDDM patients with excessive sleepiness or heavy snoring. Treatment of their OSA may improve insulin responsiveness.

Adult↗
PubMed1994

Effects of short-term NIPPV in the treatment of patients with severe obstructive sleep apnea and hypercapnia.

Although nasal continuous positive airway pressure (CPAP) is effective in the treatment of most patients with obstructive sleep apnea (OSA), there is a small group of such patients in whom rapid eye movement (REM) hypoventilation and CO2 retention persist despite the use of CPAP and supplemental oxygen. In this report we describe our experience with nocturnal nasal ventilation (nocturnal nasal positive pressure ventilation [NIPPV] in such patients and its effectiveness in reversing daytime hypercapnia. Thirteen patients, aged 28 to 69 years, with severe OSA confirmed on polysomnography, failed to respond to initial CPAP therapy. All were grossly obese (body mass index [BMI] > 35 kg.ml-1) and hypercapnic (mean PaCO2, 62 mm Hg). Nocturnal nasal ventilation was commenced using a volume-cycled ventilator, which was well tolerated in all patients. After 7 to 18 days of NIPPV, significant improvements in daytime arterial blood gas values were achieved, with a rise in arterial oxygen tension from 50 +/- 2.6 (SEM) to 66 +/- 3 mm Hg (p < 0.001) and a fall in CO2 from 62 +/- 2.5 to 46 +/- 1 mm Hg (p < 0.0001). Nine of the 13 patients were able to be established on a regimen of nasal CPAP after this period, while 3 patients required a longer period (up to 3 months) before adequate nocturnal ventilation could be maintained. In one patient, the improvements in ventilatory drive achieved with NIPPV could not be maintained on CPAP, and she was transferred on to NIPPV long term. These results indicate that effective nasal ventilation leads to an overall improvement in spontaneous ventilation and blood gas values both awake and asleep. We believe this improvement is the result of improved central ventilatory drive. Short-term NIPPV provides lasting benefits allowing the majority of such patients to resume CPAP therapy. Short-term intervention with this therapy should be considered as an interim measure in patients with severe hypercapnic OSA who fail to respond to initial CPAP therapy.

Adult↗
PubMed1994

Benefits of nocturnal nasal CPAP in patients with cystic fibrosis.

Patients with cystic fibrosis (CF) often hypoventilate during sleep with marked falls in oxygen saturation (SaO2%). This occurs most commonly during REM sleep, when there is a reduction in rib cage excursion and a fall in end-expiratory lung volume (EELV). The aim of this study was to examine the effect of nocturnal nasal continuous positive airway pressure (nCPAP) on SaO2 and the respiratory disturbance index (RDI) during sleep in patients with CF and severe lung disease. Seven patients (FEV1% pred, 23 +/- 5; range, 14 to 28%) were evaluated during sleep on two nights, control and nCPAP (11 +/- 2 cm H2O; range, 8 to 16 cm H2O), with four patients breathing room air and three patients breathing supplemental oxygen on both nights. Mean awake SaO2 was 91 +/- 1% (range, 89 to 93%). All patients showed significant oxyhemoglobin desaturation and respiratory disturbance in the control study. The maximal falls in SaO2 (15 +/- 10%) were most often associated with phasic eye movements, and a decline in rib cage excursion and the sum signal (Respitrace) during REM sleep. Nasal CPAP resulted in a significant improvement in the mean minimum oxygen saturation (MMOS) during both NREM (nCPAP 91 +/- 3% vs control 88 +/- 2%, p < 0.05) and REM sleep (nCPAP 89 +/- 6% vs control 83 +/- 6%, p < 0.05). Transcutaneous CO2 measurements were not significantly different between the control and the nCPAP studies. The RDI was also significantly reduced with nCPAP especially during REM sleep (9 +/- 7 events per hour vs control 25 +/- 11 events per hour, p < 0.05). Nasal CPAP caused no change in total sleep time or sleep efficiency yet significantly reduced the RDI and improved baseline SaO2 during both NREM and REM sleep.

Adolescent↗
PubMed1994

Relationship between chemosensitivity, obesity and blood pressure in obstructive sleep apnoea.

It has previously been documented that patients with obstructive sleep apnoea (OSA) have an abnormal blood pressure (pressor) response to acute hypoxia when awake. The relationship between hypoxic chemosensitivity and 24 h blood pressure in OSA is not known. Twenty-four hour ambulatory BP (ABP) was measured at 15 min intervals for 24 h using a non-invasive device (Oxford Medilog ABP or Spacelabs 90207 recorder) in 49 men (mean age 51 +/- 9 years), with OSA. The BP response to acute hypoxia was measured either directly (radial arterial line) or indirectly (Finapress) during wakefulness. The pressor response to hypoxia (expressed as the slope of the regression line of mean BP on % fall in arterial oxygen saturation) was compared with the results of the ABP recording, sleep study data and clinical variables. A pressor response to acute hypoxia was present in all patients (mean 1.4 +/- 1.1 mmHg/% delta SaO2, range 0.1-4.5). There was a relationship between the magnitude of the pressor response to hypoxia, severity of sleep apnoea (RDI and minimum SaO2) and central obesity (waist measurement). In contrast, there was no relationship between BP response to hypoxia during wakefulness and 24-h BP. However, increasing obesity and severity of OSA were associated with loss of the normal fall in BP at night. We conclude that enhanced chemosensitivity is common in OSA but there is no demonstrable link between chemosensitivity and mean daytime or night-time ABP.

Acute Disease↗
PubMed1994

Use of nasal mask CPAP instead of tracheostomy for palliative care in two children.

Nasal continuous positive airways pressure (nCPAP) is recommended in children for the treatment of obstructive sleep apnoea which persists following adenotonsillectomy. Nasal CPAP was successfully used in the palliative care of two severely disabled children with upper airway obstruction as an alternative to tracheostomy. Nasal CPAP resulted in the correction of obstructive apnoea in sleep, with the added benefit of sleep consolidation and fewer nocturnal arousals requiring parental attendance. There was also an unexpected benefit of reduced airway problems in the awake state in these children. Nasal CPAP is an effective form of treating upper airway obstruction for palliative care in association with other major disabilities.

Airway Obstruction↗
PubMed1993

Effect of nasal continuous positive airway pressure during sleep on 24-hour blood pressure in obstructive sleep apnea.

Ambulatory blood pressure (BP) was measured noninvasively (Oxford Medilog ABP) at 15-minute intervals for 24 hours before and after 8 weeks of treatment with nasal continuous positive airway pressure (nCPAP) in 19 men with obstructive sleep apnea (OSA). We included both normotensive and hypertensive patients, but hypertensives were studied after withdrawal of antihypertensive drugs. Ambulatory BP before and after treatment was compared using patients as their own controls. Treatment with nCPAP was successfully established in 14 of the 19 patients (74%). Blood pressure fell significantly in patients who were successfully treated: 24-hour mean BP (systolic/diastolic) decreased from 141 +/- 18/89 +/- 11 mm Hg to 134 +/- 19/85 +/- 13 mm Hg (p < 0.05). The reduction in 24-hour mean systolic BP occurred during both day and night, but a significant fall in mean diastolic BP was only observed during the day. The mean blood pressure fell in both normotensive and hypertensive patients. Patients who were inadequately treated with nCPAP had no reduction in mean 24-hour BP. Effective treatment of sleep apnea with nCPAP was associated with a significant fall in both systolic and diastolic BP independent of changes in body weight or alcohol consumption, suggesting that sleep apnea was an independent factor contributing to elevated nighttime and daytime BP in these patients.

Blood Pressure↗
PubMed1993

Breathing abnormalities in sleep in achondroplasia.

Overnight sleep studies were performed in 20 subjects with achondroplasia to document further the respiratory abnormalities present in this group. Somatosensory evoked potentials (SEPs) were recorded in 19 of the subjects to screen for the presence of brainstem abnormalities, which are one of the potential aetiological mechanisms. Fifteen children aged 1 to 14 years, and five young adults, aged 20 to 31 years were included. All had upper airway obstruction and 15 (75%) had a pathological apnoea index (greater than five per hour). Other sleep associated respiratory abnormalities, including partial obstruction, central apnoea, and abnormal electromyographic activity of accessory muscles of respiration, also showed a high prevalence. SEPs were abnormal in eight (42%), but there was no correlation between abnormal SEPs and apnoea during sleep, either qualitatively or quantitatively. A high prevalence of both sleep related respiratory abnormalities and abnormal SEPs in young subjects with achondroplasia was demonstrated. However, the sleep related respiratory abnormalities do not always result in significant blood gas disturbances or correlate with abnormal SEPs in this group.

Achondroplasia↗