Clinical Reproducibility of the Epworth Sleepiness Scale for Patients With Suspected Sleep Apnea

STUDY OBJECTIVES

To determine the reproducibility of the Epworth Sleepiness Scale (ESS) score in a clinical population referred for diagnostic testing with suspected obstructive sleep apnea.

METHODS

A retrospective audit of patients referred for a diagnostic sleep study with suspected sleep apnea was undertaken. Data collection was two 3-month time periods from January to March in 2012 and 2014. To evaluate reproducibility, the ESS score at primary care referral was compared to the ESS score at first specialist assessment/sleep assessment. The proportion of scores changing by more than 2, 3, 5, or 7 points was determined. Data were analyzed using Bland-Altman plots and paired t tests.

RESULTS

A total of 154 patients (68% male) with a mean ± standard deviation age of 51 ± 13 years, body mass index 36 ± 10 kg/m², and apnea-hypopnea index 43 ± 40 events/h were included. The average ESS score change was -0.2 with a standard deviation of 3.9 reflecting a wide scatter. A difference between the sequential ESS scores of 5 or more was seen in 21% of subjects.

CONCLUSIONS

In a clinical obstructive sleep apnea referral population, the ESS score was variable when administered sequentially. Given this variability the ESS should not be used as the sole tool to prioritize patients for obstructive sleep apnea assessment.

COMMENTARY

A commentary on this article appears in this issue on page 711.

Continuous positive airway pressure treatment for obstructive sleep apnoea: Maori, Pacific and New Zealand European experiences

INTRODUCTION

Continuous positive airway pressure (CPAP) is an effective treatment of obstructive sleep apnoea (OSA), but can be limited by poor adherence. In New Zealand (NZ), ethnicity has been shown to be a predictor of CPAP adherence. This study aimed to explore Maori , Pacific and NZ European patients' experience of CPAP treatment.

METHODS

Patients identifying as Maori , Pacific, or NZ European ethnicity referred for CPAP treatment for OSA attended separate, 1.5-hour group discussions facilitated by a health care worker of the same ethnic group, using an interview template. Thematic analysis was applied to the discussion transcripts independently by two investigators, following published guidelines.

FINDINGS

Five Maori , five Pacific, and eight NZ Europeans participated (mean age 47, range 30-71 years, mean ± standard deviation CPAP adherence 6.32 ± 1.25 hours/night). Patients in all three groups reported that they had little knowledge of OSA or CPAP prior to treatment initiation. All groups identified barriers to treatment (both at the CPAP initiation phase and long term), reported feelings of being 'overwhelmed' with information during the initial CPAP education session, and discussed the importance of successful role models. Family and friends were generally reported as being supportive of CPAP therapy.

CONCLUSION

The three groups all reported similar initial CPAP experiences, highlighting access barriers to publicly funded assessment and treatment pathways, and sleep health knowledge as key issues. Educational resources to improve access, enable self-management, and increase community awareness of OSA would help overcome some of the issues identified in this study.

The effect of continuous positive airway pressure usage on sleepiness in obstructive sleep apnoea: real effects or expectation of benefit?

RATIONALE

Placebo responses are complex psychobiological phenomena and often involve patient expectation of benefit. With continuous positive airway pressure (CPAP) treatment of obstructive sleep apnoea, greater hours of CPAP use are associated with reduced sleepiness. However, these open-label studies have not controlled for patient expectation of benefit derived from their knowledge of hours of device use.

OBJECTIVES

To investigate the relative effectiveness of the use of real or placebo CPAP on daytime sleepiness.

METHODS

Patient-level meta-analysis combining data on sleepiness measured by the Epworth Sleepiness Scale from three randomised placebo-controlled crossover trials. Mixed model analysis of variance was used to quantify the effects of real versus placebo device treatment, usage, their interaction and regression to the mean.

MEASUREMENTS AND MAIN RESULTS

Duration of real and placebo CPAP use was correlated within patients (r=0.53, p<0.001). High use of real CPAP reduced sleepiness more than high use of placebo (difference 3.0 points; 95% CI 1.7 to 4.3, p<0.001) and more than low use of real CPAP (difference 3.3; 95% CI 1.9 to 4.7, p<0.0001). High use of placebo was superior to low use of placebo (difference 1.5; 95% CI 0.1 to 2.8, p=0.03). Twenty-nine per cent of the effect of high usage of CPAP (4.2 points; 95% CI 3.3 to 5.1) was explained by the expectation of benefit effect associated with high use of placebo (1.2 points ; 95% CI 0.2 to 2.3).

CONCLUSIONS

A clinically significant proportion of the effectiveness of high CPAP use in reducing sleepiness is probably caused by patient expectation of benefit.

Ethnic disparities in CPAP adherence in New Zealand: effects of socioeconomic status, health literacy and self-efficacy

STUDY OBJECTIVES

We aimed to investigate the influence of ethnicity on adherence with continuous positive airway pressure (CPAP) in a sample of New Zealand patients.

DESIGN

Observational study over one month.

SETTING

A university-based sleep laboratory.

PATIENTS

126 consecutively consenting CPAP-naïve patients (19.8% Māori, mean±SD apnea-hypopnea index 57.9 ± 38.9 events/h, CPAP 11.1 ± 3.1 cm H2O).

INTERVENTIONS

Patients underwent a 4-week supervised home trial of CPAP following pressure titration.

MEASUREMENTS AND RESULTS

Self-identified ethnicity (Māori/non-Māori), Epworth Sleepiness Scale, Self-Efficacy Measure for Sleep Apnea, Rapid Estimate of Adult Literacy in Medicine, New Zealand Deprivation Index (calculated from residential address), New Zealand Individual Deprivation Index (validated 8-item questionnaire), educational history, income, and employment assessed at baseline were compared to objective CPAP adherence after one month. Māori demonstrated significantly lower usage than non-Māori (median 5.11, interquartile range 2.24 h/night compared with median 5.71, interquartile range 2.61 h/night, P = 0.05). There were no significant relationships between adherence and subjective sleepiness, health literacy, or self-efficacy. In a multivariate logistic regression model incorporating 5 variables (ethnicity, eligibility for government-subsidized healthcare, individual deprivation scores, income, and education), non-completion of tertiary education, and high individual socioeconomic deprivation remained significant independent predictors of average CPAP adherence not reaching ≥ 4 h (odds ratio 0.25, 95% CI 0.08-0.83, P = 0.02; odds ratio 0.10, 95% CI 0.02-0.86, P = 0.04, respectively). The overall model explained approximately 23% of the variance in adherence.

CONCLUSIONS

The disparity in CPAP adherence demonstrated between Māori and non-Māori can be explained in part by lower education levels and socioeconomic status.

Home set-up polysomnography in the assessment of suspected obstructive sleep apnea

Home set-up polysomnography (PSG) has advantages over other portable monitoring devices, but remains unendorsed by professional bodies despite excellent utility in the Sleep Heart Health Study (SHHS). The study aims to determine technical reliability and diagnostic accuracy of unattended, home set-up versus attended laboratory-based PSG in patients with suspected obstructive sleep apnea (OSA). Thirty patients with suspected OSA without significant co-morbidity were recruited. After initial lab-PSG (Compumedics S series), patients underwent home set-up PSG (Compumedics Siesta) and lab-based PSG in random order. Studies were compared for study success, signal loss and likelihood ratio for OSA diagnosis [apnea-hypopnea index (AHI) >10]. Thirty subjects (mean age 49±13.8 years, body mass index 31±6.1 kg m(-2) ) completed investigations. SHHS technical acceptability criteria were met by all lab-based PSGs and 90% of home-based PSGs (93% clinically acceptable). Signal loss was higher at home (P=0.008). Sleep efficiency was similar between sites, but more preferred home-based PSG (50%). ancova revealed AHI was significantly different if initial AHI >26 per h (P=0.006), with an average underestimate of 5.1 per h at home. In technically acceptable studies the likelihood ratios to 'rule in' and 'rule out' OSA were 8.1 and 0.1, respectively. Unattended, home set-up PSG is technically reliable and achieves excellent diagnostic utility. Signal loss was higher at home but mitigated by multi-channel redundancy. Success rate was similar to SHHS and superior to laboratory set-up home studies. Home set-up PSG is a valid alternative to laboratory-based PSG for suspected OSA.

Pulse wave analysis in a pilot randomised controlled trial of auto-adjusting and continuous positive airway pressure for obstructive sleep apnoea

PURPOSE

Non-invasive measurements of arterial stiffness including the augmentation index (AIx) and central blood pressure (BP) have been used to assess the cardiovascular health of patients with obstructive sleep apnoea (OSA), a well-established independent risk factor of cardiovascular disease. Continuous positive airway pressure (CPAP) can significantly reduce the AIx, but no studies have analysed the effect of auto-adjusting PAP (APAP) or studied morbidly obese patients with severe OSA at higher risk of cardiovascular disease. In this randomised, single-blinded crossover pilot trial, we aimed to compare the efficacy of CPAP with APAP (ResMed S8 Autoset II) in improving peripheral BP, central BP and the AIx, using SphygmoCor technology.

METHODS

Twelve severe OSA patients (mean±SD; apnoea-hypopnoea index, 75.8 ± 32.7; BMI, 49.9 ± 5.2 kg/m(2)) were consecutively recruited and received CPAP (mean pressure, 16.4 cm H(2)O) or APAP in random order for four nights at home, separated by a four-night washout. Cardiovascular measurements were taken at baseline, post-washout and following each treatment arm.

RESULTS

The polysomnographically recorded residual apnoea-hypopnoea index and compliance to treatment were not significantly different between arms (p > 0.05). There were no significant differences in peripheral or central BP between arms (p > 0.05). The AIx was lower with CPAP than APAP (by 5.8%), with a large effect size not reaching statistical significance (r = 0.61, p = 0.14).

CONCLUSION

The large effect size evident when comparing the AIx following CPAP and APAP indicates the need to perform an adequately powered trial in order to determine if APAP improves arterial stiffness to the same extent as CPAP.

Shoulder dystocia: room for improvement?

A questionnaire was completed by 166 midwives and obstetric junior doctors to assess their knowledge of the management of shoulder dystocia and to establish whether mandatory teaching and updating is required. Ninety-six participants (58%) claimed they were confident in the management of shoulder dystocia. However, only six (4%) respondents gained full marks on the scoring system devised to assess their knowledge. Furthermore 36 (22%) of those surveyed suggested rotation of the shoulders to the anterior-posterior position to alleviate the dystocia and 32 (19%) proposed pulling the head hard. Although there are limitations in assessing competence by the use of a questionnaire, the results of this survey suggest that there is considerable room for improvement. We suggest that a shoulder dystocia drill is introduced to all labour wards in the United Kingdom so that birth attendants can develop and memorize a sequence of procedures to use when confronted with this life-threatening emergency.

Continuous positive airway pressure in heart failure patients with obstructive sleep apnoea

BACKGROUND

The aim of the study was to study the effect of 6 months of continuous positive airway pressure (CPAP) in community heart failure (HF) patients with obstructive sleep apnoea (OSA).

METHODS

Clinically stable outpatients with HF and OSA (left ventricular ejection fraction (LVEF) <45%, apnoea/hypopnoea index >15/h, n = 19) treated with CPAP and a control group (LVEF <45%, apnoea/hypopnoea index <10/h, n = 7) were compared at baseline and at 6 months by Minnesota heart failure score, Epworth sleepiness score, shuttle walk distance, brain natriuretic peptide, urinary catecholamines and echocardiographic indices using paired t-test, McNemar's tests and effect sizes.

RESULTS

In HF patients with OSA, CPAP improved LVEF (35.9 +/- 6.1% to 40.6 +/- 8.0%, P = 0.015), decreased LV end-systolic volume (152 +/- 74 to 135 +/- 62 cm(3), P = 0.03), systolic blood pressure (P = 0.04) and sleepiness (Epworth sleepiness score 8.8 +/- 4.8 to 6.3 +/- 3.2, P = 0.01), whereas walk distance, catecholamines, brain natriuretic peptide levels and symptoms were unchanged. These outcomes did not change in the HF control group.

CONCLUSION

In community HF patients with OSA, CPAP therapy over 6 months improved LVEF, systolic blood pressure and sleepiness, but not sympathetic activation, brain natriuretic peptide or exercise levels. Acceptance was relatively low, potentially limiting therapeutic effectiveness.

Continuous positive airway pressure reduces daytime sleepiness in mild to moderate obstructive sleep apnoea: a meta-analysis

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) affects an estimated 2-4% of the middle aged population. Meta-analyses of randomised controlled trials have shown that the severe presentation of the syndrome (apnoea hypopnoea index (AHI) >30/hour) is effectively treated with continuous positive airway pressure (CPAP). Until recently there have been insufficient data to determine whether CPAP improves sleepiness in the larger subgroup with mild to moderate OSAS (AHI 5-30/hour).

METHODS

A systematic search of Medline and a hand search identified seven randomised controlled trials where CPAP was compared with either a placebo or with conservative management in the treatment of mild to moderate OSAS (AHI 5-30/hour). All trials used the Epworth Sleepiness Scale (ESS), four used the Multiple Sleep Latency Test (MSLT), and three used the Maintenance of Wakefulness Test (MWT) to measure sleepiness.

RESULTS

Meta-analyses indicated that CPAP significantly reduced subjective daytime sleepiness (ESS) by 1.2 points (95% CI 0.5 to 1.9, p = 0.001), improved objective daytime wakefulness (MWT) by 2.1 minutes (95% CI 0.5 to 3.7, p = 0.011), but did not affect objective daytime sleepiness (MSLT, mean benefit -0.2 minutes, 95% CI -1.0 to 0.6, p = 0.6). The two significant effects were small (effect size <0.30).

CONCLUSIONS

CPAP elicits small improvements in subjective sleepiness and objective wakefulness in people with mild to moderate OSAS. However, the effects on sleepiness are of limited clinical significance.

Randomised controlled crossover trial of humidified continuous positive airway pressure in mild obstructive sleep apnoea

BACKGROUND

It is unclear whether continuous positive airway pressure (CPAP), the treatment of choice for severe obstructive sleep apnoea (OSA), is effective at improving outcomes in mild OSA.

METHODS

To help define the role of humidified CPAP in mild OSA, a randomised crossover study was undertaken of patients with an apnoea hypopnoea index (AHI) of 5-30/hour. Subjective sleepiness, objective wakefulness, mood, reaction time, and quality of life were measured at baseline, after 3 weeks treatment with humidified CPAP and 3 weeks sham CPAP (2 week washout).

RESULTS

Twenty nine of 31 enrolled patients (age 25-67 years, seven women, mean (SD) body mass index 31.5 (6) kg/m2) completed the protocol. Humidified CPAP improved polysomnographic indices of OSA and Epworth Sleepiness Scale (2.4 points (95% CI 0.6 to 4.2)). Objective wakefulness (modified maintenance of wakefulness test) showed a trend towards improvement (5.2 minutes (95% CI -0.6 to 11)). Mood (Hospital Anxiety and Depression Scale), quality of life (SF 36, Functional Outcomes of Sleep Questionnaire), and reaction times (Psychomotor Vigilance Task) were not improved more than sham CPAP. Compliance with humidified and sham CPAP both averaged 4.9 hours/night. Placebo effects were evident in many outcomes and there was no clear treatment preference.

CONCLUSIONS

Humidified CPAP improves subjective sleepiness and possibly objective wakefulness but not reaction times, quality of life, or mood. These results do not support the routine use of CPAP in all patients with mild OSA, but offers some support for the trialling of CPAP in those with severe sleepiness.

The 'Folic Acid Campaign': has the message got through? A questionnaire study

There is now clear evidence that folic acid reduces the risk of neural tube defects. In February 1996 the Health Education Authority launched a publicity campaign to inform women of the benefits of periconceptual folic acid. We have surveyed 1000 women to assess the compliance of pregnant women with the Department of Health's recommendations about taking folic acid. Of the women, 761 (76%) said they knew about the benefits of folic acid but only 433 (43%) of them took it before pregnancy. Of the 567 women who did not take folic acid before conception, 227 had not planned their pregnancy and 239 did not know about the benefits. Of the 644 women who planned their pregnancy and knew about the benefits of folic acid before conception 211 still did not take folic acid pre-pregnancy. These findings have important implications for public policy and health professionals if the incidence of neural tube defect is to be reduced further.

Humidified nasal continuous positive airway pressure in obstructive sleep apnoea

Heated humidification of nasal continuous positive airway pressure (nCPAP) reduces upper airway symptoms and improves initial use in obstructive sleep apnoea syndrome (OSAS). The present study aimed to assess the effect of heated humidification of nCPAP on upper airway symptoms and initial use in obstructive sleep apnoea. This study was of a randomised, crossover design. Subjects with polysomnographically confirmed OSAS were randomised to 3 weeks nCPAP treatment with heated humidification (nCPAP-humid) or placebo humidification (nCPAP pl-humid). Objective and subjective nCPAP use, upper airway symptoms, and treatment satisfaction were compared. Thirty seven of 42 patients completed the protocol. nCPAP-humid reduced the frequency of adverse upper airway symptoms. nCPAP use over 3 weeks was greater with nCPAP-humid compared with nCPAP pl-humid. No difference was found between the treatment arms in terms of subjective treatment satisfaction or alertness. Heated humidification of nasal continuous positive airway pressure reduces upper airway symptoms and is associated with a small increase in initial use but not subjective sleepiness or treatment satisfaction. The results support the use of heated humidification as a strategy to reduce side-effects related to continuous positive airway pressure but not routine initial use.

A randomized controlled trial of continuous positive airway pressure in mild obstructive sleep apnea

A common clinical dilemma faced by sleep physicians is in deciding the level of severity at which patients with obstructive sleep apnea (OSA) should be treated. There is particular uncertainty about the need for, and the effectiveness of, treatment in mild cases. To help define the role of nasal continuous positive airway pressure (CPAP) treatment in mild OSA we undertook a randomized controlled cross-over trial of CPAP in patients with an apnea- hypopnea index (AHI) of 5 - 30 (mean, 12.9 +/- 6.3 SD). Twenty-four-hour blood pressure and neurobehavioral function were measured at baseline, after 8 wk of treatment with CPAP, and after 8 wk of treatment with an oral placebo tablet. Twenty-eight of 42 patients enrolled in the study completed both treatment arms. Baseline characteristics were not different between those who completed the study and those who did not complete the study. Patients used CPAP for a mean (SD) of 3.53 (2.13) h per night and the mean AHI on the night of CPAP implementation was 4.24 (2.9). Nasal CPAP improved self-reported symptoms of OSA, including snoring, restless sleep, daytime sleepiness, and irritability (in-house questionnaire), more than did placebo, but did not improve objective (Multiple Sleep Latency Test) or subjective (Epworth Sleepiness Scale) measures of daytime sleepiness. We found no benefit of CPAP over placebo in any tests of neurobehavioral function, generic SF-36 (36-item Short Form Medical Outcomes Survey) or sleep-specific (Functional Outcomes of Sleep Questionnaire) quality of life questionnaires, mood score (Profile of Moods States and Beck Depression Index), or 24-h blood pressure. However, the placebo tablet resulted in a significant improvement in a wide range of functional variables compared with baseline. This placebo effect may account for some of the treatment responses to CPAP observed previously in patients with mild OSA.

Hazards of assisted conception in women with severe medical disease

The issues relating to assisted reproduction in women with severe medical disease can be divided into the likely effect of pregnancy upon the medical condition, and how the medical condition may adversely affect pregnancy outcome. In addition, consideration of the hazards relating to the process of assisted conception, in particular the risk of ovarian hyperstimulation syndrome and multiple pregnancy, must be remembered. In some women, successful assisted reproduction may result in a life-threatening pregnancy. Clinicians advising women about assisted conception should be aware of the medical conditions that are absolute contra-indications to pregnancy. Some women with severe medical disease may have a significantly reduced life expectancy, in which case ethical issues regarding the future welfare of the child must be considered. Examples include sickle cell disease, cystic fibrosis and HIV. One of the biggest advantages of assisted reproduction for women with severe medical disorders is that the pregnancy is planned. Thus, there is an opportunity for the patient to be informed fully about any risks, both to herself and her fetus. This article reviews the general management of women with severe medical disorders who seek assisted reproduction and gives specific guidelines for the more common conditions.

The pharmacokinetics of oral fleroxacin and ciprofloxacin in plasma and sputum during acute and chronic dosing

AIMS

To examine the pharmacokinetics of ciprofloxacin and fleroxacin in plasma and sputum of patients with an acute exacerbation of chronic bronchitis or bronchiectasis following the first dose and again during the third day of treatment.

METHODS

Twelve patients, aged >35 years, with acute infective exacerbation of bronchitis or bronchiectasis were allocated randomly to treatment with either fleroxacin 400 mg daily or ciprofloxacin 500 mg twice daily in an open, parallel group design. Plasma and sputum were collected during the first and third days of treatment. The time course of concentrations in sputum was modelled assuming that it acted as a negligibly small compartment of distribution.

RESULTS

The mean sputum to plasma ratios of both ciprofloxacin and fleroxacin were approximately 1 on both days 1 and 3. Peak concentrations of ciprofloxacin in sputum were achieved 1.6 (95% CI on mean difference 0.8-2.3) and 1.2 (0.4-1.9) h later than in plasma on day 1 and day 3, respectively (mean difference +/- 95% confidence interval). For fleroxacin, the corresponding delay in time to peak concentrations was less marked and not significant. Fleroxacin accumulated in plasma (accumulation index 1.52+/-0.07) and sputum (accumulation index 1.79+/-0.39) from day 1 to day 3. Accumulation did not occur for ciprofloxacin because the dose interval (12 h) was considerable longer than its half life (3-4 h).

CONCLUSIONS

The sputum to plasma ratio of ciprofloxacin and fleroxacin is approximately 1. The time to peak concentrations of ciprofloxacin in sputum is slightly delayed compared with plasma. Fleroxacin accumulates over time in both plasma and sputum consistent with its longer half-life.

Legionella, Chlamydia pneumoniae and Mycoplasma infection in patients admitted to Christchurch Hospital with pneumonia

AIMS

To determine the incidence, clinical features and outcome of community acquired pneumonia caused by Mycoplasma pneumoniae, Legionella species, Coxiella burnetti, Chlamydia pneumoniae and Chlamydia psittaci requiring admission to hospital.

METHODS

Over 12 months the clinical findings and severity of pneumonia were recorded prospectively. Sputum, blood, serum and urine samples were collected for diagnostic testing. Management was supervised by the admitting medical team. Subjects were followed-up six weeks after discharge.

RESULTS

Two hundred and fifty-five patients met the entry criteria of whom 20 died, including five who had Legionella infection. M pneumoniae (16%) infection was more often of mild/moderate severity (95%), occurred in a younger age group (mean age 31.4 years, p=0.002), with more frequent myalgia and headache. The length of hospital stay was shorter and clearing of chest radiograph and return to normal activity occurred more rapidly in this group of patients. Legionellosis was common as judged by culture and serological testing (26 cases, 11%) and a further 22 cases were identified by polymerase chain reaction. Legionella infection was not distinguishable clinically from other pneumonias. C pneumoniae was uncommon (8 cases, 3%). C burnetti and C psittaci were not identified in this study.

CONCLUSIONS

Some cases of pneumonia caused by Mycoplasma pneumoniae can be identified at presentation, however pneumonia due to Legionella is not distinguishable on clinical grounds. Development of molecular diagnostic techniques may enable therapy to be directed against specific organisms earlier in the course of the disease.

Daytime pulmonary hemodynamics in patients with obstructive sleep apnea without lung disease

It is controversial whether obstructive sleep apnea (OSA) causes pulmonary hypertension (PH) in the absence of hypoxemic lung disease. To investigate this further we measured awake pulmonary hemodynamics, pulmonary gas exchange, and small airways function in 32 patients with OSA (apnea- hypopnea index, mean +/- SE, 46.2 +/- 3. 9/h) who had normal screening lung function. Pulmonary artery pressure (Ppa) and cardiac output were measured by Doppler echocardiography at three levels of inspired oxygen (FIO2 0.50, 0.21, and 0.11) and during incremental increases in pulmonary blood flow (10, 20, and 30 microgram/kg/min dobutamine infusions) while breathing 50% oxygen. Eleven patients had PH (mean Ppa >/= 20 mm Hg, Group I). They did not differ from patients without PH (Group II) in lung function, severity of sleep-disordered breathing, age, or body mass. Compared with Group II, Group I patients had increased small airways closure during tidal breathing (FRC-closing capacity: Group I, -0.16 +/- 0.11; Group II, 0.27 +/- 0.09 L; p < 0.05), more ventilation-perfusion inequality (AaPO2: 23.8 +/- 2.8; 19.8 +/- 1.4 mm Hg; p = 0.08), a greater pulmonary artery pressor response to hypoxia (DeltaPpa FIO2, 0.50 to 0.11: 16.4 +/- 1.93; 6.4 +/- 0.77 mm Hg; p < 0.05) and a marked rise in Ppa during increased pulmonary blood flow. We conclude that PH may develop in some patients with OSA without lung disease and that it is associated with small airways closure during tidal breathing and heightened pulmonary pressor responses to hypoxia and during increased pulmonary blood flow. Such changes are consistent with remodeling of the pulmonary vascular bed in affected patients with OSA, seemingly unrelated to severity of sleep-disordered breathing.

Portable computerized polysomnography in attended and unattended settings

STUDY OBJECTIVE

We compared the validity of a new portable polysomnographic recorder against a laboratory-based polysomnographic system from the same manufacturer.

DESIGN AND PATIENTS

Simultaneous, full polysomnographic recordings from the portable device (PSGP) and the laboratory-based system (PSGL) were obtained using separate sets of sensors on 20 patients referred for investigation of sleep apnea.

SETTING

After initial optimization of signals, the portable device was left unattended in 10 of the patients (to simulate home studies), while in the other 10 the signals were reviewed on a laptop computer screen and adjustments to electrode or sensor placement made as needed during the studies. Recordings were manually scored by a technologist blinded to the origin of the data.

MEASUREMENTS AND RESULTS

The quality of signals was comparable between the PSGP and PSGL studies, apart from a slight decrease in respiratory signal quality during PSGP studies that led to reduced confidence in respiratory event scoring. SaO2 signal loss was also greater in unattended PSGP. There was good agreement between PSGP and PSGL for sleep variables and the apnea-hypopnea index (r=0.99). The periodic limb movement index was slightly lower during unattended PSGP. Blinded physician assessment of the records led to a recommendation for repeat studies due to poor signal quality in one (10%) attended and one (10%) unattended portable recording. There was no significant discordance between PSGP and PSGL in the final diagnostic formulations.

CONCLUSION

Portable polysomnography is a viable alternative to laboratory-based polysomnography and may be improved further by better sensor attachment.

Effects of sleep posture on upper airway stability in patients with obstructive sleep apnea

Changes in sleep posture have been shown to improve obstructive sleep apnea (OSA). To investigate the mechanisms by which this occurs we assessed upper airway stability in eight patients with severe OSA in three postures (supine, elevated to 30 degrees, and lateral). We used a specially adapted nasal continuous positive airway pressure (nCPAP) mask to measure upper airway closing pressure (UACP) and upper airway opening pressure (UAOP) during non-REM sleep. Statistical comparisons were made between postures using ANOVA for repeated measures. Elevation resulted in a less collapsible airway compared with both the supine and lateral positions (mean UACP: 30 degrees elevation -4.0 +/- 3.2 compared with supine 0.3 +/- 2.4 cm H2O, p < 0.05 and; lateral -1.1 +/- 2.2 cm H2O, p < 0.05). Supine UACP and lateral UACP were not significantly different. Elevation or lateral positioning produced a 50% reduction in mean UAOP (supine 10.4 +/- 3.5 cm H2O compared with 30 degrees elevation 5.3 +/- 2.1, p < 0.05; and lateral 5.5 +/- 2.1 cm H2O, p < 0.05). We conclude that in severely affected OSA patients upper body elevation, and to a lesser extent lateral positioning, significantly improve upper airway stability during sleep, and may allow therapeutic levels of nCPAP to be substantially reduced.

Community acquired pneumonia: aetiology and usefulness of severity criteria on admission

BACKGROUND

Community acquired pneumonia remains an important cause of hospital admission and carries an appreciable mortality. Criteria for the assessment of severity during admission have been developed by the British Thoracic Society (BTS). A study was performed to determine the sensitivity and specificity of a severity rule based on a modification of the BTS prognostic rules applied on admission, to compare severity as assessed by medical staff with the modified rule, and to determine the microbiological cause of community acquired pneumonia in Christchurch.

METHODS

A 12 month study of all adults admitted to Christchurch Hospital with community acquired pneumonia was undertaken. Three hundred and sixteen consecutive patients with suspected community acquired pneumonia were screened for inclusion. Variables obtained from the history, examination, investigations, and initial treatment were examined for association with mortality.

RESULTS

Two hundred and fifty five patients met the inclusion criteria. Their mean age was 58 years (range 18-97). A microbiological diagnosis was made in 181 cases (71%), Streptococcus pneumonia (39%), Mycoplasma pneumoniae (16%), Legionella species (11%), and Haemophilus influenzae (11%) being the most commonly identified organisms. Patients had a 36-fold increased risk of death if any two of the following were present on admission: respiratory rate > or = 30/min, diastolic BP < or = 60 mm Hg, urea > 7 mmol/l, or confusion. The severity rule identified 19 of the 20 patients who died and six of eight patients admitted to the intensive care unit as having life threatening community acquired pneumonia. The sensitivity of the modified rule for predicting death was 0.95 and the specificity 0.71. In 47 cases (21%) the clinical team appeared to underestimate the severity of the illness.

CONCLUSIONS

The organisms responsible for community acquired pneumonia in Christchurch are similar to those reported from other centres except for Legionella species which were more common than in most studies. The modification of the BTS prognostic rules applied as a severity indicator at admission performed well and could be incorporated into management guidelines.

An audit of the assessment and management of patients admitted to Christchurch Hospital with chronic obstructive pulmonary disease

AIM

To audit the assessment and management of patients admitted to hospital with chronic obstructive pulmonary disease (COPD) during three months of the winter of 1992.

METHODS

Consensus management guidelines were developed as the basis for the audit. Consecutive cases were audited by review of the case notes. Half were admitted initially under a respiratory physician and half under a general physician. Ninety-five cases were audited.

RESULTS

The overall standard of medical assessment was adequate but a number of deficiencies were identified. The mean duration of stay in hospital was nine days. In the emergency department the use of pulse oximetry in preference to arterial blood gas analysis led to failure to diagnose significant ventilatory failure in five cases. Initial assessment by junior medical staff failed to include comment about level of consciousness in 50% of cases and chest hyperinflation in 40%. Oxygen therapy was given in 87% of cases, but was not prescribed in one third and was often not adequately monitored. Peak flow monitoring was performed on admission in 74% of cases and arterial blood gas measurement in 81%. Over 90% of patients were given nebulised bronchodilator therapy with both nebulised ipratropium bromide and salbutamol. Antibiotics were given in 77% of cases. Corticosteroids were given in 95% of cases, usually orally. Sedatives were prescribed inappropriately in six cases where there was acute ventilatory failure. Four patients died in hospital, none unexpectedly. Three patients were mechanically ventilated and all survived to leave hospital. There was no discharge summary in the case records in 29% of cases.

CONCLUSIONS

Standards of assessment and treatment were adequate. Several areas were identified where improvements are required, particularly in the prescribing and monitoring of oxygen therapy. Hospital-wide guidelines for the management of COPD are to be developed.