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Biomedical subjects

K Harvey

Publications and source records attributed to K Harvey.

At least 73 records · Page 4Linked to original sources

Use of antibiotic agents in a large teaching hospital. The impact of Antibiotic Guidelines.

Three surveys of antibiotic use have been conducted at The Royal Melbourne Hospital. The first was conducted in 1978, before the introduction of the booklet, Antibiotic Guidelines; the second was conducted eight months after, and the most recent, four years after, its distribution. In 1978, 30% of 563 patients surveyed were receiving antibiotic therapy; this proportion declined to 28% of 967 patients studied in 1982. At the beginning of 1978, 52% of all treatments audited were judged appropriate when compared with those recommended in the Guidelines; this proportion rose to 72% in the second survey and was maintained at 70% in 1982. Certain inappropriate prescribing patterns persisted, such as the use of amoxycillin for the treatment of primary pneumonia, surgical antibiotic prophylaxis which was started too late, and the failure to simplify therapy when the results of microbiological investigations became available. Antibiotic guidelines facilitate the auditing of antibiotic usage and aid rational prescribing. Nevertheless, additional measures appear necessary if specific patterns of misuse of antibiotic agents are to be corrected.

Amoxicillin↗

Effects of balloon volume and position on the pressure volume curve of the lung.

Pressure-vol. (PV) curves of the lung were obtained in 2 groups of normal subjects using different esophageal balloon vols. and balloon positions. The PV curves were fitted to the exponential V = A - Be-KP. Transpulmonary pressures at different %S of total lung capacity and specific compliance were calculated. Variation in balloon vol. over the range 0.2-2.0 ml had no effect on the shape of the PV curve, as reflected by the exponential constant K, or specific compliance. Transpulmonary pressures were significantly different when the balloon vol. was 0.2 ml. With the balloon positioned at 8 or 12 cm from the gastro-esophageal junction there was no change in PV curve parameters but transpulmonary pressures and K were significantly altered at the 4 cm position. We conclude that, for clinical purposes, exact positioning of the esophageal balloon and use of the precise resting balloon vol. are not critical. Highly reproducible measurements of the elastic properties of the lung may be obtained using an esophageal balloon with a vol. of 0.6-1.0 ml and a position 8-12 cm from the gastro-esophageal junction.

Adult↗

Antibiotic-associated diarrhoea and methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus was thought to be the cause of 10 cases of antibiotic-associated diarrhoea observed over a 12-month period at The Royal Melbourne Hospital. Each patient had significant underlying disease, and all had been treated with multiple, broad-spectrum antibiotic agents. The diagnosis was made on the distinctive Gram-stain appearance of faecal smears, the heavy predominant growth of methicillin-resistant Staph. aureus from stool cultures, and the absence of other bowel pathogens, including toxigenic Clostridium difficile. Diarrhoea usually responded to treatment with vancomycin or bacitracin, and, in patients whose condition improved, the stools cleared of staphylococci. Patients with staphylococcal diarrhoea present a significant crossinfection risk, and early diagnosis, treatment, and isolation are essential.

Adult↗

Methicillin resistance in Staphylococcus aureus with particular reference to Victorian strains.

There is controversy regarding methods employed for the detection of methicillin resistance in Staphylococcus aureus, and dispute whether infections caused by these organisms can be successfully treated with methicillin or similar antibiotic agents. Cell populations of methicillin-resistant Staph. aureus (MRSA) are heterogeneous with respect to the level of resistance expressed, but always contain a subpopulation of highly resistant cells which can neither be inhibited nor killed by beta-lactam antibiotic agents. Clinical experience confirms that in severe infections, particularly when host defences are imparied, the use of beta-lactam antibiotic agents to treat MRSA is associated with an unacceptably high failure rate. Current Victorian strains of MRSA are multiresistant. Thus vancomycin is the drug of choice for life-threatening infections, while the combination of fusidic acid either with flucloxacillin or with rifampicin is useful for infections of moderate severity.

Australia↗

Epidemic of hospital-acquired infection due to methicillin-resistant Staphylococcus aureus in major Victorian hospitals.

During 1979, the Victorian Health Commission received reports of a rising proportion of methicillin-resistant Staphylococcus aureus (MRSA) isolates from an increasing number of institutions. At least 31 metropolitan hospitals were involved, and six of these reported MRSA totaling between 20% and 40% of all Staph. aureus isolates. Since that time, the problem has continued. In some university teaching hospitals, strains of MRSA now cause from 200 to 300 new cases of hospital-acquired infection each year. Sepsis occurs mainly in patients who underwent surgery, premature neonates and in the immunocompromised or debilitated patients. The organism involved is multiresistant. Recent isolates show increasing resistance, particularly against gentamicin, chloramphenicol and, more lately, fusidic acid and rifampicin. Only vancomycin can be relied upon for empirical treatment. There is concern that increasing use of vancomycin will select vancomycin-resistant strains of MRSA, so that, in the near future, there may no longer be any effective antibiotic therapy against hospital staphylococci.

Australia↗

Refractory period fluid stimulation of right atria: a method for studying presynaptic receptors in cardiac autonomic transmission.

A method is described for measuring the atrial period or beat interval from the surface electrogram in isolated spontaneously contracting guinea pig right atria. Stimulation of parasympathetic and sympathetic nerve endings can be readily obtained by applying electrical field pulses across the atria during the atrial refractory period to prevent arrhythmia. In the presence of atropine, the atria respond to a single field pulse with a slight tachycardia that can be taken as a measure of the released transmitter norepinephrine. Because the effector response is mediated by a beta-adrenoreceptor, this preparation is particularly suited for the study of the pharmacology of presynaptic alpha-adrenoreceptors. The fall in period (tachycardia) to one-, two-, or four-field pulses delivered one per consecutive refractory period is linear, and the responses are reproducible for many hours. This biological system offers advantages in sensitivity and stability over methods employing radiolabeled norepinephrine in the study of presynaptic receptors in cardiac autonomic transmission.

Animals↗

Sleep loss in young adolescents.

Effects of one night's sleep loss on nocturnal sleep, performance, and sleepiness were evaluated in 12 subjects (8 boys, 4 girls) whose ages ranged from 11.7 to 14.6 years. The magnitude and direction of sleep stage changes after sleep loss were comparable to similar findings in older subjects. Performance test decrements occurred for two measures during sleep deprivation. The performance decrements appeared to be related to episodes of sleep during the performance tests. Subjective measures of sleepiness showed a significant increase during sleep loss, with a complete recovery to basal levels after one night of sleep. The subjective ratings of sleepiness during sleep loss also showed a marked short-term dependence on preceding activity levels. Multiple sleep latency tests showed a marked reduction of sleep onset latency from 0530 throughout the day of sleep loss. In contrast to the subjective measures, sleep latency test scores did not vary with activity levels during sleep loss and did not recover to basal levels until the afternoon of the first recovery day. In general, there were no marked differences in the sleep loss response of young adolescents as compared to published reports of sleep loss in older subjects.

Adolescent↗

Pubertal changes in daytime sleepiness.

Nineteen children (8 girls, 11 boys) were evaluated in a total of 47 three-day sessions across three summers. Children were ranked according to Tanner's stages of secondary sexual characteristics. Nocturnal sleep was recorded from 2200 to 0800 hr each night. Multiple sleep latency tests were given at 2 hr intervals from 0930 each day. Nocturnal sleep time and REM sleep time remained constant across Tanner stages. Slow wave sleep time declined progressively across Tanner stages, with a 40% reduction from prepuberty to maturity. Daytime sleepiness was significantly greater in subjects at Tanner stages 3 and 4 than at Tanner stages 1 and 2. Subjects at Tanner stage 5 tended to be as sleepy as Tanner stage 3 and 4 subjects but did not differ significantly from the less mature subjects. No gender differences were found in daytime sleepiness for children at similar Tanner stages. More mature children were significantly sleepier at 1330 and 1530 than in the late afternoon and evening.

Adolescent↗

Sleep habits of children and the identification of pathologically sleepy children.

Sleep disorders and daytime sleepiness have been investigated only minimally in children. The sleep habits of 218 children, ages 10-13 years, were surveyed by a sleep habits questionnaire (SHQ). Our results demonstrate that total night time sleep on school nights begins to fall in early adolescence, whereas it remains relatively stable on non-school nights. Daytime sleepiness is not a common problem in this age group, in contrast to a college age population. We conclude that in adolescence chronic sleep deficits begin to occur which cumulatively affect later functioning. The potential use of the SHQ for depicting pathological sleepiness is also discussed.

Adolescent↗

Respiration during sleep in children.

In 22 children (11 boys and 11 girls), aged 9 to 13 years, respiration was monitored during one night of sleep. No child had a significant history of breathing problems during sleep. Sleep was recorded using standard techniques (electroencephalography, electrooculography, electromyography), and respiration was measured with nasal thermistors and abdominal or thoracic strain gauges. Respiratory pauses (five seconds or longer) were determined for all sleep stages. Respiratory rate was scored only in the first and last sleep cycles and during ten waking minutes before sleep onset. Respiratory rate was significantly affected by wakefulness or stage of sleep: highest in wakefulness and stage 1, lowest in stage 2 of the last sleep cycle. Regularity of respiratory rate showed a similar effect. Variance of respiratory rate was significantly lower in girls than boys. Respiratory pauses during sleep were seen in every child, ranging from 3 to 40 pauses per night (average, 17.2 for boys and 18.0 for girls). Significantly greater numbers of pauses per minute were seen in stage 1 and rapid eye movement (REM) sleep than in stages 2, 3 and 4. The longest respiratory pause was 25 seconds. The conclusion is made that a small number of respiratory pauses during sleep are normal in children of this age.

Adolescent↗

Acinetobacter septicaemia following prolonged intravenous therapy.

A 76-year-old man developed septicaemia during the infusion of stable plasma protein solution (SPPS) which was subsequently shown to be contaminated with Acinetobacter anitratus. Septicaemia persisted for four days despite change of the intravenous cannula and administration of an appropriate antibiotic. Clinical improvement occurred only when the entire intravenous line, (infusion bottle, airway needle, giving set and intravenous cannula), all of which grew Acinetobacter, was replaced. Contamination of the SPPS probably occurred in the ward via a contaminated giving set and airway needle, which had been in use for one week. This case illustrates the importance of following accepted guidelines for infection control in intravenous therapy.

Acinetobacter↗

A case of chancroid.

After a visit to Hong Kong, a 27-year-old salesman developed penile ulceration which failed to respond to three weeks' penicillin therapy. He then presented to hospital with acute paraphimosis. A clinical diagnosis of chancroid was confirmed by isolation of Haemophilus ducreyi. The ulcers healed after sulphonamide and streptomycin therapy. Although chancroid is an uncommon venereal disease in Australia, its incidence is still high in many tropical countries. It should be considered as a possible cause of genital ulceration in patients who have travelled overseas.

Adult↗