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Biomedical subjects

S Davidson

Publications and source records attributed to S Davidson.

At least 55 records · Page 3Linked to original sources
PubMed1999

The sevoflurane-sparing effect of nitrous oxide: a clinical study.

BACKGROUND: We studied the sevoflurane-sparing effect of nitrous oxide in a prospective randomised study. METHODS: Forty-two ASA I-II patients scheduled for elective knee arthroscopy under general anaesthesia were randomly assigned to a fresh gas flow consisting of oxygen in air or oxygen in nitrous oxide 1:2. All patients received a standardised anaesthesia consisting of induction with fentanyl and propofol and maintenance with sevoflurane adjusted according to clinical signs. The sevoflurane consumption was studied by means of weighing the vaporiser before and after every anaesthesia. RESULTS: The mean sevoflurane consumption was reduced from 0.62 to 0.25 g/min, a 60% reduction, by the use of oxygen in nitrous oxide 1:2 in the fresh gas flow. The emergence was faster for the patients receiving nitrous oxide. No major differences were observed during recovery. CONCLUSION: Nitrous oxide was found to be cost-effective for use during short ambulatory knee arthroscopy.

Adolescent↗
PubMed1999

Severe disruptive vocalizers.

OBJECTIVES: To describe the most severe disruptive vocalizers in nursing facilities, in regard to their clinical and behavioral characteristics, staff responses, and treatments used, and to report on their prognosis over 6 months. DESIGN: A longitudinal cohort study. SETTING: One hundred seven skilled nursing facilities. PARTICIPANTS: The 203 residents who were among the two most disruptive vocalizers in their respective facilities and who vocalized at least 2 hours a day. MEASUREMENTS: Telephone interviews of licensed nursing staff who cared for the subjects, conducted at baseline, 2, 4, and 6 months. Data gathered included subject demographics, physical function, diagnoses, medication and restraint use, behavioral problems, vocalization characteristics, treatments used, and status at follow-up. RESULTS: Subjects tended to have dementia, to be dependent in most activities of daily living, to have multiple medical problems, to be physically restrained (48%), and to be taking psychotropic medication (76%). Nearly all (95%) were audible at least 50 feet away, with loudness associated with more severe cognitive impairment (OR 4.90, P = .001). When subjects who primarily made nonverbal noises ("screamers") were compared with those whose predominant expressions were words ("talkers"), hearing impairment, severe cognitive impairment, and greater dependency in activities of daily living characterized the screamers. Staff reported trying a variety of treatments with all subjects, often with little success. Two months after enrollment, 66% of surviving subjects vocalized fewer hours than at baseline, and 45% were rated as improved. Independent predictors of improvement included greater ADL independence, hearing and vision problems, shorter length of stay, urinary incontinence, and use of a treatment other than one-on-one interventions. Nearly one-quarter of subjects (23.4%) died within 6 months. Baseline factors associated independently with a higher probability of death included age, use of activity intervention, physical abusiveness, and absence of wandering. CONCLUSION: Severe disruptive vocalization is associated with severe cognitive and physical impairment and with a high probability of mortality within 6 months. Subcategorization of severe vocalizers by vocalization type or other associated factors may be useful for prognostic and treatment purposes.

Activities of Daily Living↗
PubMed1999

Radiation exposure of Certified Registered Nurse Anesthetists during ureteroscopic procedures using fluoroscopy.

Due to the use of fluoroscopy in the operating room, Certified Registered Nurse Anesthetists (CRNAs) frequently are exposed to the dangers of radiation emitted during surgical procedures using fluoroscopy. The purposes of this research were to determine the level of radiation exposure of the CRNA during fluoroscopic procedures in the operating room and to determine whether these levels are within the limits of maximum permissible dose equivalents published in the Code of Federal Regulations (CFR). This research was conducted in an operating room specifically designated for urological procedures using fluoroscopy. A stationary dosimeter was used to measure radiation exposure. The dosimeter was exchanged monthly for 6 months. Data from this study confirmed that the total radiation exposure was above the limit set by the CFR for whole body radiation exposure, thus exposing the thyroid, which is typically unprotected. The data from this study also supported earlier works that suggested that the radiation to the lens of the eye is of little concern since the exposure rarely exceeds the dose limits set by the CFR.

Certification↗
PubMed1999

Maternal pre-pregnancy weight and placental weight determine birth weight in normal Jamaican infants.

Birth weight is related to neonatal health and long-term risk of chronic disease. Since animal studies have shown that birth outcome is related to placental function, the present project was designed to explore the relationship between birth weight and placental growth and composition with maternal factors during pregnancy among normal term pregnancies in 51 primiparous and 40 multiparous women delivering at the University Hospital of the West Indies. Both groups were followed from 15 weeks of gestation to term. The primiparous group was generally younger than the multiparous (mean age 22 +/- 4 versus 31 +/- 5 yr). They were significantly lighter (55 +/- 8 versus 61 +/- 9 kg) with a lower body mass index (21 +/- 3 versus 23 +/- 4 kg/m2) during early pregnancy, but gained more weight during pregnancy, 11 kg compared with 8 kg, respectively. The duration of pregnancy was similar for both groups. Although the size of the placenta was not significantly different between the two groups, the mean weight of the multiparous placentae was more than that of the primiparous placentae. Also, for all mothers both placental weight and initial maternal weight related directly to birth weight. Placental non collagen protein (NCP), sodium and potassium contents were significantly higher for multiparous women and were related to birth weight. The primiparous group had babies who were significantly lighter, 3.03 kg compared with 3.36 kg, for the multiparous and this could be attributed to differences in placental function and maternal weight. When account was taken of the difference in maternal weight at the start of pregnancy and the difference in placental weight, parity no longer explained any of the differences in birth weight. It is concluded that maternal body weight at the time of becoming pregnant and the early development of the placenta determine the efficiency with which nutrients might be delivered to the foetus and hence foetal growth. The difference in birth weight between primiparous and multiparous women can be explained by the differences in maternal weight at the time of becoming pregnant.

Adult↗
PubMed1998

Potential use of a novel lipase from Aspergillus carneus in deacetylation reactions.

A novel lipase from Aspergillus carneus has been used in organic solvents for efficient regioselective and chemoselective deacetylation of the peracetates of polyphenolic aromatic ketones, esters and amides. A reversal of regioselectivity was observed as compared with the results obtained during deacetylation with porcine pancreatic lipase (PPL).

Acetates↗
PubMed1998

The effect of thermal stimulation on the heart-rate variability in neonates.

Thermoregulation in humans can be divided into three broad mechanisms of control, namely: shivering, sweating and vasomotor activity. Previous investigations suggested the presence of an autonomic rhythm, originating in the central nervous system, possibly related to thermal vasomotor control and directly affecting heart rate by reflex changes in cardiac sympathetic and parasympathetic activity. The objective of the present work was to study the maturation process of the thermoregulatory system in newborns. We used peripheral thermal entrainment and focused on the reflections of vasomotor control in the heart-rate (HR) power spectrum (PS). The study included three groups of neonates at three different ages: 10 premature infants, 6 full-terms and 7 older infants (4 to 6 months). Thermal stimulation was achieved by placing a hot and cold surface on the subject's right palm alternately at three different rates: replacing the touching surface every 4 s (0.25 Hz), 7 s (0.14 Hz) and 10 s (0.1 Hz). 'Double period' stimulation was defined as the total duration of each period of hot and cold stimulation at the three rates, namely 8 s (0.125 Hz), 14 s (0.07 Hz), 20 s (0.05 Hz). The ECG of every infant was measured and recorded during the various stages of the experiment. The HR power spectrum from 0.02 Hz up to 2.00 Hz was considered, focusing on narrow ranges around the thermal stimulation frequencies. We found that in most subjects, clear peaks arise in the HR PS at the thermal entrainment frequency and its corresponding half frequency ('double period'). In premature infants, the reaction is best in response to the longest (10 s) stimulus (9 out of 10 prematures reacted positively), in group B (full-term infants) the reaction responds best to the 7-s stimulus (6 out of 6 reacted) and in older infants the reaction is slightly better at the 4-s stimulus. Since sympathetic control is slower, this ability to entrain the control system at increasing frequencies, might be related to the gradual maturation of parasympathetic control after birth. The different reaction of the three groups may help to understand the maturation process of the thermoregulation system.

Adaptation, Biological↗
PubMed1998

Lipase production by Aspergillus and Penicillium species.

Forty each of aspergilli and penicillia were screened for extracellular lipase production on agar plates and in liquid medium containing olive oil as substrate. Twenty-nine aspergilli and twenty-six penicillia produced lipase. Out of these, 19 aspergilli and 22 penicillia showed activity both on Nile blue sulfate and glycerol tributyrate agar plates while only 10 aspergilli and 4 penicillia showed a positive response to glycerol tributyrate agar alone. The screening revealed 11 Aspergillus spp. and 15 Penicillium spp. as new lipase producers. Pig fat as an economic substrate for lipase production was also investigated.

Animals↗
PubMed1998

Weight-bearing patterns on the knees of preterm infants.

In this study we present a method of monitoring the forces under the knees of preterm infants lying in the prone position. Dual force sensing resistor transducers, connected to optically-isolated amplifiers, were used to monitor the forces. A thermistor airflow sensor was used for the parallel monitoring of the respiratory signal. The measurements were made on ten preterm infants. The average forces were 0.51 and 0.50 N for the left and right knees, respectively. In the frequency domain, the basic harmonic of the force traces was 1.27 Hz approximately, corresponding to the respiratory rhythm. Additional, smaller harmonics, were detected in the force traces at 2.54 and 3.81 Hz. A rather notable power signal could also be seen around 0.1 Hz. The results obtained indicate that the system developed is highly sensitive for providing data on the amplitudes, periods and sequences of oscillations and symmetry of load bearing in preterm infants. Knowledge of the normal and abnormal reaction force patterns may assist in the early diagnosis of abnormal neurodevelopment.

Humans↗
PubMed1998

Nursing care of personality disorders in the medical surgery setting.

When patients with personality disorders are treated for medical conditions in an acute care setting, nurses are frequently unaware of the diagnosis. Yet the behavior patterns can create problems for both patient and nursing staff. This article will (1) present an overview of personality disorders; (2) examine personality characteristics of patients with borderline and antisocial personality disorders and the difficulties that arise from splitting, impulsiveness, suicide attempts, manipulation, and aggression; and (3) discuss intervention strategies the nurse who encounters a patient exhibiting a personality disorder can use.

Aggression↗
PubMed1997

Spectral analysis of heart rate fluctuations and optimum thermal management for low birth weight infants.

Spectral analysis of heart rate variability is studied in 10 healthy growing premature infants to investigate the changes in autonomic balance achieved as a function of changes in skin temperature. Heart rate is obtained from ECG recordings and the power spectrum of beat-to-beat heart rate fluctuations is computed. The infants maintain mean rectal temperature within 36.3-37.2 degrees C, while skin temperature changes. The respiratory rate does not change at the different servocontrol set points. Heart rate is found to increase slightly, but consistently. The low-frequency band (0.02-0.2 Hz), reflecting the interplay of the sympathetic and parasympathetic tone and known to be maximum at the thermoneutral zone, is maximum at 35.5 and 36 degrees C and decreases gradually to a lower level at a servocontrol temperature of 36.5-37 degrees C. The high-frequency band (0.2-2.0 Hz), coinciding with the respiratory peak and reflecting parasympathetic activity, is significantly elevated at 36 degrees C (p < 0.01). The minimum low: high ratio, indicating the minimum sympathetic-parasympathetic balance and possibly reflecting the most comfortable conditions, occurs at 36 degrees C, although the differences are not statistically significant. Servocontrol skin temperature may thus be adapted, and possibly selected at 36 degrees C for growing premature infants in an attempt to achieve thermal comfort and more balanced autonomic activity.

Electrocardiography↗
PubMed1997

Management of the patient with disruptive vocalization.

Disruptive vocalization (DV) is a common problem in the management of cognitively and physically impaired older people. This article reports the results of a consensus meeting convened to provide guidelines for clinicians and recommendations for researchers in this difficult and little-studied behavioral problem. DV arises largely in people with cognitive impairment and generally reflects an underlying need or discomfort. A variety of factors can precipitate and aggravate DV; the key to management is appropriate identification of all possible factors and development of an individualized treatment plan.

Aged↗