Predictors of blood pressure fall with continuous positive airway pressure (CPAP) treatment of obstructive sleep apnoea (OSA).

BACKGROUND: Obstructive sleep apnoea (OSA) is associated with high cardiovascular morbidity and mortality. Randomised controlled trials have shown that, on average, treatment of OSA with continuous positive airway pressure (CPAP) reduces blood pressure (BP) by 3-5 mm Hg, although with considerable variation between individuals. No predictors of the change in BP with CPAP have been convincingly identified. This prospective study aimed to determine predictors of BP change, which might provide an insight into the aetiology of the raised BP seen in untreated OSA. METHODS: Eighty-six patients with daytime hypersomnolence warranting treatment with CPAP were recruited. 24 h mean BP (24 hMBP), subjective sleepiness, fasting venous blood samples and anthropometric measurements were assessed at baseline and after 6 months of CPAP treatment. RESULTS: The mean (SD) 24 hMBP fell at 6 months from 101.0 (10.3) mm Hg to 96.1 (9.1) mm Hg (change -4.92 mm Hg (95% CI -2.8 to -7.1)). The Epworth Sleepiness Score (ESS) fell from a median of 16 (IQR 12-18) to 4 (2-7) with a mean fall of 9.7 (95% CI 8.6 to 10.8). Several factors correlated with the fall in 24 hMBP but, after allowing for the baseline 24 hMBP, only the fall in ESS and the body mass index (BMI) remained significant independent predictors (p = 0.006 and 0.007, respectively). There was also a correlation between the fall in 24 hMBP and the fall in pulse rate (r = 0.44, p<0.001). Baseline severity of OSA, overnight hypoxia, caffeine intake or being on antihypertensive drugs were not independent predictors of a fall in 24 hMBP. CONCLUSION: Improvement in hypersomnolence and the BMI are independent correlates of the fall in 24 hMBP following CPAP therapy. Markers of initial OSA severity did not predict the fall in 24 hMBP. This suggests that sleep fragmentation and its effects may be more important than hypoxia in the pathogenesis of the hypertension associated with human sleep apnoea.

Continuous positive airway pressure does not reduce blood pressure in nonsleepy hypertensive OSA patients.

Obstructive sleep apnoea (OSA) is associated with high cardiovascular morbidity and mortality. Several randomised controlled trials have shown that continuous positive airway pressure (CPAP) treatment of OSA reduces blood pressure (BP). This randomised, sham-placebo controlled crossover trial assesses whether CPAP produces a similar clinically significant fall in BP in hypertensive OSA patients, but without hypersomnolence. Thirty-five, nonsleepy, hypertensive patients with OSA were treated with CPAP for 1 month, randomised first to either therapeutic or sham-placebo (subtherapeutic CPAP, about 1 cmH(2)O pressure). The second months' alternative treatment followed a 2-week washout period. BP was measured over 24 h, before and at the end of the two treatment periods: mean 24-h BP was the primary outcome variable. There was no overall significant difference in mean 24-h BP: the change in mean 24-h BP on therapeutic CPAP was -2.1 mmHg (sd 8.1), and -1.1 mmHg (sd 8.1) on subtherapeutic CPAP, with a difference of 0.7 mmHg (95% confidence interval (CI) +2.9- -4.4). There was a small significant fall in Epworth Sleepiness Score, therapeutic (-1.4) versus sham (-0.3), and difference -1.2 (95% CI -2.0- -0.4), but no change in objective sleepiness. In nonhypersomnolent hypertensive patients with obstructive sleep apnoea, there is no significant fall in mean 24-h blood pressure with continuous positive airway pressure, in contrast to the fall seen in hypersomnolent patients with obstructive sleep apnoea.

Sleep . 6: obstructive sleep apnoea/hypopnoea syndrome and hypertension.

The use of CPAP to control excessive daytime sleepiness in OSAHS probably also produces a substantial reduction in vascular risk. This is reviewed with particular reference to hypertension.

Circulating cardiovascular risk factors in obstructive sleep apnoea: data from randomised controlled trials.

BACKGROUND: Obstructive sleep apnoea (OSA) is associated with high cardiovascular morbidity and mortality and is an independent risk factor for hypertension. Novel circulating cardiovascular risk markers enabling a more accurate prediction of cardiovascular risk have been identified. Examination of these markers may clarify the increased risk in OSA and contribute to an analysis of the benefits of treatment. METHODS: Plasma levels of total cholesterol and triglyceride and activated coagulation factors XIIa and VIIa, factors VII, VIII, XII, fibrinogen, thrombin-antithrombin (TAT), von Willebrand factor antigen (vWFAg), soluble P-selectin (sP-sel), and homocysteine were measured before and after treatment for 1 month with therapeutic or subtherapeutic (control) continuous positive airways pressure (CPAP) in 220 patients with OSA. RESULTS: Levels of activated coagulation factors XIIa, VIIa, TAT and sP-sel were higher in OSA patients at baseline than in unmatched controls, but did not fall with 1 month of therapeutic CPAP treatment. The raised sP-sel levels correlated only with body mass index (p = 0.002). There was a trend towards a significant fall in total cholesterol with therapeutic CPAP (p = 0.06) compared with the control group. In the therapeutic group there was a clinically significant mean fall in total cholesterol of 0.28 mmol/l (95% confidence interval 0.11 to 0.45, p = 0.001) which may reduce cardiovascular risk by about 15%. CONCLUSION: A number of activated coagulation factors are increased in untreated OSA patients, potentially contributing to vascular risk, but they do not fall with 1 month of CPAP treatment. Nasal CPAP may produce a clinically relevant fall in total cholesterol level, potentially reducing cardiovascular risk, but this needs to be verified in a larger prospective study.

Caffeine levels following treatment of obstructive sleep apnoea.

BACKGROUND: Randomised trials show that treatment of obstructive sleep apnoea (OSA) with nasal continuous positive airway pressure (CPAP) greatly improves sleepiness and also lowers diurnal systemic blood pressures (BP). Such patients consume more coffee than controls (presumably to combat their sleepiness) and might reduce their consumption following effective treatment, thus lowering BP by this mechanism rather than via a direct effect of alleviating OSA. METHODS: Plasma caffeine levels before and after treatment with either therapeutic (n=52) or subtherapeutic (control, n=49) CPAP were measured in stored blood samples from a previous randomised controlled trial of CPAP for 4 weeks in patients with OSA. RESULTS: There was a small significant rise in caffeine levels when the two groups were analysed as a whole (p=0.02), but not individually. Despite the fall in sleepiness measured objectively in the therapeutic CPAP group, there was no difference in absolute (or change in) caffeine levels between the two groups (mean (SE) micro mol/l; therapeutic CPAP 9.2 (1.2), 10.2 (1.0), subtherapeutic 6.7 (0.9), 8.6 (0.9) before and after treatment, respectively). CONCLUSION: Reduced coffee consumption is unlikely to be the explanation for the falls in BP following treatment of OSA.

Topical acyclovir treatment of herpes zoster in immunocompromised patients.

Topical acyclovir favorably influences the healing of localized herpes zoster in immunocompromised patients. This therapy, or placebo, was applied to forty-three patients in a random access, double-blind trial, four times daily for 10 days, beginning within 72 hours after the onset of skin lesions. The mean time to pustulation is decreased from 12.4 to 6.7 days and the mean time to crusting is decreased from 16.0 to 11.4 days (p = 0.038 and 0.086, respectively) by topical treatment. The mean time to 50% healing is decreased from 24.5 to 15.2 days and the mean time to 100% healing is decreased from 34.9 to 25.8 days (p = 0.023 and 0.033, respectively). Favorable effects in treated patients are not associated with a more rapid decline in lesion virus titer, but do accrue without any toxicity.

Brief report: nosocomial infection rates in a cancer treatment center.

This report describes the results of a prospective study of nosocomial infection in 7,714 patients hospitalized during a 24-month period at a cancer treatment center. An overall nosocomial infection rate of 9.3% was observed with site-specific infection rates of 2.6% for urinary tract, 1.9% for surgical wound, 2.2% for bacteremia and 1.9% for respiratory tract infection. Within specific patient groups, the overall nosocomial infection rates observed were: 8.2% in medical patients, 14.9% in surgical patients and 1.5% in pediatric patients. Despite the markedly elevated nosocomial infection rate in surgical patients (P less than 0.001), surgical wound infection rates were not unlike those observed in general hospitals: clean-2.4%, clean contaminated-5.8%, contaminated-13.2%, and dirty-11.8%. These observations provide evidence that institutions which provide medical care predominantly for cancer patients can expect to observe higher nosocomial infection rates than general care hospitals.

A prospective analysis of nosocomial wound infection after mastectomy.

We evaluated the postoperative course of all patients who had mastectomies from 1978 through 1982 at City of Hope National Medical Center (Duarte, Calif). The overall clean mastectomy wound infection rate was 24/294 (8.2%). The incidence of mastectomy wound infection varied with the method of biopsy and was 3.2% after needle aspiration and 9.5% after open biopsy. Mastectomy immediately after open biopsy ("one step") had an infection rate of 5.3%, whereas mastectomy at a subsequent procedure ("two step") had a rate of 12.4%. The maximal infection rate (23.0%) occurred following the two-step procedure when the interval was four to seven days. The infection rates for patients hospitalized three or more days before mastectomy were elevated, but no significant correlation was observed between the infection rate and other demographic factors. We recommend that needle aspiration biopsy be used prior to open biopsy to minimize the need for a two-step approach to mastectomy.