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Biomedical subjects

P W Munt

Publications and source records attributed to P W Munt.

At least 19 recordsLinked to original sources
PubMed2005

Effect of treating severe nasal obstruction on the severity of obstructive sleep apnoea.

An association between mouth breathing during sleep and increased propensity for upper airway collapse is well documented, but the effect of treatment for nasal obstruction on mouth breathing during sleep and simultaneous obstructive sleep apnoea (OSA) severity has not been described previously. A randomised single blind placebo- and sham-controlled crossover study of treatment (topical decongestant and external dilator strip) for nasal obstruction was carried out in 10 patients (nine males; mean+/-SEM 46+/-5 yrs) with nasal obstruction and OSA. All patients had normal acoustic pharyngometry. The effect of treatment on nasal resistance, mouth breathing during sleep and OSA severity was quantified. Treatment of nasal obstruction was associated with a dramatic and sustained reduction in nasal resistance and the oral fraction of ventilation during sleep (mean (95% confidence interval) absolute reduction in oral fraction 30% (12-49)). Improvements in sleep architecture were observed during active treatment, and there was a modest reduction in OSA severity (change in apnoea-hypopnoea index 12 (3-22)). In conclusion, treating nasal obstruction reduced mouth breathing during sleep and obstructive sleep apnoea severity, but did not effectively alleviate obstructive sleep apnoea.

Administration, Intranasal↗
PubMed2001

How do prolonged wakefulness and alcohol compare in the decrements they produce on a simulated driving task?

The effects of alcohol ingestion were compared with those of prolonged wakefulness on a simulated driving task. Eighteen healthy, male subjects aged between 19 and 35 years drove for 30 min on a simulated driving task at blood alcohol concentrations of 0.00, 0.05 and 0.08%. Subjective sleepiness was assessed before and after the driving task. Driving performance was measured in terms of the mean and standard deviation (S.D.) of lane position (tracking); the mean and S.D. of speed deviation (the difference between the actual speed and the posted speed limit); and the number of off-road occurrences. Ratings of sleepiness increased with increasing blood alcohol concentration, and were higher following the driving task. With increasing blood alcohol concentration, tracking variability, speed variability, and off-road events increased, while speed deviation decreased, the result of subjects driving faster. The results were compared with a previous study examining simulated driving performance during one night of prolonged wakefulness [Arnedt, J.T., MacLean A.W., 1996. Effects of sleep loss on urban and motorway driving stimulation performance. Presented at the Drive Alert... Arrive Alive International Forum, Washington DC], using an approach adopted by Dawson and Reid [Dawson, D., Reid, K., 1997. Fatigue, alcohol and performance impairment. Nature 388, 23]. For mean tracking, tracking variability, and speed variability 18.5 and 21 h of wakefulness produced changes of the same magnitude as 0.05 and 0.08% blood alcohol concentration, respectively. Alcohol consumption produced changes in speed deviation and off-road occurrences of greater magnitude than the corresponding levels of prolonged wakefulness. While limited to situations in which there is no other traffic present, the findings suggest that impairments in simulated driving are evident even at relatively modest blood alcohol levels, and that wakefulness prolonged by as little as 3 h can produce decrements in the ability to maintain speed and road position as serious as those found at the legal limits of alcohol consumption.

Adult↗
PubMed2001

Do patients with obstructive sleep apnea have clinically significant proteinuria?

AIM: Previous studies report a high prevalence of proteinuria in patients with obstructive sleep apnea syndrome (OSAS). This common syndrome may therefore be an important cause ofproteinuria and renal failure in the general population. This study was undertaken to assess the prevalence of proteinuria among OSAS patients, and to identify the factors associated with urine protein excretion in these patients. METHODS: Overnight polysomnography, urine protein to creatinine ratio (PTCR), body mass index (BMI), mean arterial pressure (MAP), and hematocrit were assessed prospectively in 224 patients referred for evaluation of suspected OSAS. Sleep apnea was defined as apnea-hypopnea score (AHS) > or = 5 events/hour. Proteinuria was defined as PTCR > 0.2 mg/mg. RESULTS: Sleep apnea was present in 143 subjects (63.8%), and proteinuria in 10 (4.5%). The highest PTCR was 0.677 mg/mg. PTCR and AHS were weakly correlated (r = 0.12, p = 0.08). PTCR correlated (alpha = 0.05) with lowest oxygen saturation (r = -0.18, p = < 0.01), time spent with oxygen saturation below 90% (r = 0.19, p = < 0.01), and BMI (r= 0. 17, p = < 0.01). The mean PTCR was similar in subjects with and without sleep apnea. Proteinuria was present in 7 of 143 (4.9%) subjects with AHS > or = 5 and 3 of 81 (3.7%) subjects with AHS < 5, a relative risk of 1.34, 95% CI (0.34, 5.32). Predictors of LogPTCR in multiple linear regression (model R2 - 0.104) were: AHS (< 5 or > or = 5), baseline oxygen saturation, sex, and MAP. CONCLUSIONS: Clinically significant proteinuria is uncommon in OSAS. The prevalence and severity of proteinuria are similar in both OSAS patients and patients without sleep-disordered breathing. Sleep apnea severity is weakly associated with urine protein excretion, related more to hypoxemia than to frequency of apneic events.

Analysis of Variance↗
PubMed2000

Simulated driving performance following prolonged wakefulness and alcohol consumption: separate and combined contributions to impairment.

The separate and combined effects of prolonged wakefulness and alcohol were compared on measures of subjective sleepiness, simulated driving performance and drivers' ability to judge impairment. Twenty-two males aged between 19 and 35 years were tested on four occasions. Subjects drove for 30 min on a simulated driving task under conditions determined by the factorial combination of 16 and 20 h of wakefulness and blood alcohol concentrations of 0.00 and 0.08%. The simulated driving session took place 30 min postingestion; subjects in the two alcohol conditions participated in a second 30-min driving session 90-min postingestion. Subjects made simultaneous ratings of their impairment while driving and retrospective ratings at the end of each test session. Subjective sleepiness measures were completed before and after each driving session. The combination of 20 h of prolonged wakefulness and alcohol produced significantly lower ratings of subjective sleepiness and driving performance that was worse, but not significantly so, than would be expected from the additive effects of each condition alone. Driving performance was always worse in the second driving session, during the elimination phase of alcohol metabolism, despite blood alcohol concentrations being lower than during the first driving session. There was a modest association between perceived and actual impairments in driving performance following prolonged wakefulness and alcohol. The findings suggest that the combination of prolonged wakefulness and alcohol consumption produced greater decrements in simulated driving performance than each condition alone and that drivers have only a modest ability to appreciate the magnitude of their impairment.

Adult↗
PubMed1995

Desquamative interstitial pneumonitis and diffuse alveolar damage in textile workers. Potential role of mycotoxins.

Five of 88 workers at a textile plant developed interstitial lung disease. Biopsy specimens from the three initial cases demonstrated desquamative interstitial pneumonitis and diffuse alveolar damage. Two of these patients developed hypoxemic respiratory failure despite high-dose corticosteroid therapy. A survey of the remaining textile workers (questionnaires, chest radiographs, and pulmonary function tests) revealed one new case. This patient, and one other with a compatible presentation, improved clinically upon leaving the workplace and did not require therapy. A comprehensive assessment of the work environment was performed in search of potentially toxic respirable agents. We propose that these cases represent desquamative interstitial pneumonitis-like reactions, occupationally related to aflatoxin inhalation.

Adult↗
PubMed1991

Nonsurgical treatment of Histoplasma endocarditis involving a bioprosthetic valve.

Endocardial involvement associated with disseminated histoplasmosis has been infrequently documented, especially among patients with prosthetic valves. The therapeutic approach to these patients is also not yet clearly defined. A 54-year-old man with prosthetic valve endocarditis due to histoplasmosis was successfully treated with amphotericin B. A review of the literature suggests that the optimal form of therapy is likely a combination of surgical replacement of the involved valve and high dose amphotericin B. Successful therapy with amphotericin B alone may, however, be achieved if surgery is not a viable option.

Amphotericin B↗
PubMed1989

Influence of the menstrual cycle on airway function in asthmatic and normal subjects.

Investigations of premenstrual asthma (PMA) have been based on studies of asthmatics already aware of a deterioration of asthma premenstrually. Little is known, therefore, about relationships between the menstrual cycle and airway function in asthmatics who do not complain of PMA or in normal subjects. We investigated airway function in both of these groups for three or four consecutive menstrual cycles. Daily records of asthma symptoms and peak expiratory flow rates were maintained by 11 asthmatics and 29 normal control subjects. Standard spirometry and serum estradiol and progesterone levels were measured during the follicular, midluteal, and late luteal phases of the menstrual cycle. Airway reactivity to methacholine was tested during the follicular and luteal phases. The normal group showed no significant changes in symptoms, peak flow rates, spirometric parameters, or airway reactivity. Although the asthmatic group also demonstrated no significant changes in spirometry and airway reactivity, asthma symptoms (shortness-of-breath, cough, wheeze, and chest tightness) deteriorated significantly (p less than 0.001) from the follicular to the luteal phase, as did the morning peak flows of the asthmatics (p = 0.045). Airway function and reactivity were not related to hormone levels in either group. This study indicates that asthmatics not previously aware of PMA will record a premenstrual worsening of asthma symptoms and peak expiratory flow rates. These changes are not related to a deterioration in spirometry and airway reactivity or to the absolute levels of circulating progesterone and estradiol.

Adult↗
PubMed1989

Oxygenation in patients with chronic airflow obstruction after cessation of exercise.

Although oxygenation has been widely investigated in patients with chronic airflow obstruction both at rest and during exercise, very little is known about their oxygenation in the postexercise recovery period. Recently, it has been shown that PaO2 may in fact be higher during the initial 20 to 120 seconds recovery phase, compared to rest and peak exercise levels. Since it is not established to what extent this improvement persists, we investigated the changes in oxygenation during this phase in patients with CAO. We measured arterial blood gas values, expired gases and ventilation at rest, peak exercise and during the first seven minutes of recovery in 18 male patients with moderate-severe CAO. Mean rest PaO2 (77 mm Hg) and peak exercise PaO2 (76 mm Hg) did not change significantly. Compared to peak exercise, PaO2 was significantly higher during recovery at one minute (93 mm Hg, p = 0.005) and at four minutes (91 mm Hg, p = 0.005), but not at seven minutes (86 mm Hg, p = 0.155) after exercise. All of the recovery PaO2 levels were significantly higher than resting PaO2. These results indicate that during the postexercise recovery period, oxygenation is better than at peak exercise or at rest. Regression analysis of the data predicts that oxygenation may return to resting levels 8 to 9 minutes after cessation of exercise.

Aged↗
PubMed1986

Simultaneous use of membrane oxygenation and high-frequency jet ventilation in acute pulmonary failure.

A 16-yr-old female suffering acute, rapidly progressive combined respiratory and cardiac failure that was unresponsive to conventional volume-cycled ventilation, was stabilized with the simultaneous short-term use of veno-venous membrane oxygenation and high-frequency jet ventilation. Percutaneously introduced cannulas afforded rapid vascular access for membrane oxygenation, minimal wound problems during the perfusion, and easy decannulation. This is the first reported combined use of high-frequency jet ventilation and extracorporeal membrane oxygenation, and the first reported percutaneous initiation of veno-venous bypass. The patient remained alive and well 4 months after therapy.

Acute Disease↗
PubMed1984

Use of mechanical ventilation in adults with severe asthma.

Asthma severe enough to require intubation and mechanical ventilation is associated with a mortality rate of about 10%. Therapeutic modalities are ever-changing and at times controversial. This paper provides an update on such modalities and presents, in a step-wise fashion, those most appropriate for practical patient care. The timing of intubation and the methods used to control airway patency, arterial pH and gas levels, and hemodynamic status are crucial to the success of therapy. Finally, conventional and disputed methods of bronchodilation are outlined.

Acute Disease↗
PubMed1984

Theophylline clearance. Lack of effect of influenza vaccination and ascorbic acid.

Warnings have been issued regarding safety in the use of theophylline preparations in patients receiving influenza vaccination. These were prompted by reports that influenza vaccination caused inhibition of metabolism of theophylline and aminopyrine. Previous work has indicated a role for ascorbic acid in mixed function oxidase activity, and ascorbic acid is commonly used by the public. We studied the effect of influenza vaccination and ascorbic acid supplementation on the rate of elimination of theophylline. In 11 patients and 12 normal subjects no significant effects of influenza vaccination or ascorbic acid supplementation on theophylline clearance, serum half-life, or apparent volume of distribution were detected (p greater than 0.3). We conclude that neither influenza vaccination nor ascorbic acid supplementation induce a predictable effect on theophylline disposition.

Adult↗
PubMed1984

Theophylline reassessed.

Advances have recently been made in understanding the pharmacokinetics of theophylline. To correlate the new knowledge of theophylline pharmacokinetics with the drug's current status in therapy, we have critically reviewed the relevant investigations of the last 5 years. We consider data on its presumed mechanisms of action, factors affecting its clearance, its use in pregnancy, treatment of overdoses, and important drug interactions. Theophylline clearance is decreased by concomitant use of erythromycin, cimetidine, high-dose allopurinol, oral contraceptives, and caffeine. Clearance is increased by concomitant use of phenobarbital and phenytoin. Newly discovered actions of theophylline include dose-dependent improvement of diaphragmatic contractility, augmentation of ventilatory response to hypoxia, and sleep disturbances (especially with high-dose treatments). Points clinically relevant to the daily use of theophylline derivatives and the importance of sustained-release preparations are discussed. Theophylline continues to play a major role in therapy for reactive airways disease.

Acidosis↗
PubMed1981

Dose-dependency of theophylline clearance and protein binding.

Dose-dependency in theophylline pharmacokinetics and protein binding characteristics was examined in 10 healthy male volunteers. Theophylline disposition was determined after an intravenous infusion of both 1 mg/kg and 6 mg/kg aminophylline in a randomised crossover study. There was considerable intrasubject variability in theophylline clearance but no significant dose-dependency. Theophylline protein binding was assessed by equilibrium dialysis at varying theophylline concentrations. The percentage of free non-protein bound theophylline was significantly increased at high theophylline concentrations. This increase in free theophylline would lead to a non-linear increase in the risk of toxicity with increasing drug concentration.

Adult↗
PubMed1979

Theophylline-7-acetic acid: lack of absorption and therapeutic effectiveness.

A double-blind cross-over trial was conducted to evaluate the effectiveness of oral theophylline-7-acetic acid (T7AA) in 13 asthmatic patients. Pulmonary function tests showed no difference between T7AA and placebo. No T7AA or theophylline was found in the sera of these patients or of healthy volunteers who took T7AA tablets or syrup.

Adult↗