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Biomedical subjects

W F Dick

Publications and source records attributed to W F Dick.

46 records · Page 3Linked to original sources
PubMed1994

Thiopentone, thiopentone/ketamine, and ketamine for induction of anaesthesia in caesarean section.

Seventy-five healthy patients were randomly allocated to receive thiopentone, thiopentone/ketamine or ketamine for induction of anaesthesia for elective Caesarean section. Thiopentone resulted in the most pronounced and ketamine in the smallest drop in blood pressure, while the combination induced only moderate haemodynamic changes. Intra-operative awareness occurred in one patient in the thiopentone group, six of the ketamine patients had nightmares, and one patient of the combination group reported pleasant dreams but no awareness. The muscle tone of neonates in the thiopentone group was more reduced than in neonates in the other two groups. Infants delivered after uterine incision-to-delivery intervals exceeding 3 min more often had Apgar scores < 7 than those delivered in less than 3 min.

Adult↗
PubMed1993

[Fiberoptic intubation and stress].

Nasotracheal intubation of the trachea by means of fiberoptic endoscopy is an accepted approach to difficult airways. The associated avoidance of direct laryngoscopy may affect the stress response to nasotracheal intubation. We tested this hypothesis by means of a prospective, randomized, controlled clinical study. METHODS. Informed consent was obtained from 30 patients presenting for maxillofacial surgery for participation in this study. Patients were allocated to three groups: nasotracheal intubation to be performed either fiberendoscopically (group 1) or laryngoscopically, with (group 2) or without (group 3) topical anaesthesia of the larynx. Haemodynamic variables (arterial blood pressure and heart rate) and concentrations of catecholamines* in plasma (adrenaline, noradrenaline; HPLC) were documented at four (two*) time points, respectively: prior to induction of anaesthesia*, after induction, 1 min after tracheal intubation*, 5 min after tracheal intubation. Differences between time points and between groups were analysed with the chi-square test; a probability of P < 0.05 was considered statistically significant. RESULTS. With respect to age, body-weight and gender, the groups were comparable. No major hemodynamic or endocrine stress responses were observed in any group. Diastolic blood pressures were significantly lower in groups one and two, one minute after tracheal intubation. DISCUSSION. Nasotracheal intubation does not provoke a major stress response, when performed in accordance with the protocol of this study. However, topical anaesthesia of the larynx, as well as the fiberendoscopic approach proved superior to control with respect to diastolic arterial pressure. We conclude that fiberoptic nasotracheal intubation, or laryngoscopy preceded by topical anaesthesia of the larynx may be useful in patients for whom an increase in rate pressure product would be undesirable.

Adolescent↗
PubMed1992

Protocol for studying depth of anesthesia using the spectral edge frequency.

The preliminary results of a multicenter study designed to determine the utility of the processed EEG in combination with heart rate and blood pressure for estimating anesthetic depth are reported. The study is planned to include 1,000 ASA I, II, and III patients undergoing surgery with at least a 60-minute duration of anesthesia. The preliminary results indicate that the use of EEG and clinical signs may provide better control of anesthetic depth. The study design provides ideal conditions for determining whether spectral edge frequency is a useful criterion for management of routine general anesthesia in a typical clinical environment.

Anesthesia, General↗
PubMed1990

Ornithine and S-adenosylmethionine decarboxylase activities and polyamine contents in developing muscle tissues and primary cultures of normal and polymyopathic hamsters.

Polyamine (putrescine, spermidine, and spermine) contents and ornithine (ODC) and S-adenosylmethionine (SAMDC) decarboxylase activities have been assessed in an age-dependent manner, in normal and polymyopathic (dystrophic) hamster skeletal muscle, heart, and tongue extract and in primary tongue myoblast and skin fibroblast cultures. At 2 weeks of age, polyamine contents were significantly elevated in all of the dystrophic hamster tissues studied when compared with their age-matched controls. The degree of this elevation decreased with the age of the animals, generally, to a level where no significant difference in polyamine contents could be noted between normal and dystrophic hamster tissues. ODC and SAMDC activities in whole tissue extracts were consistently highest in 2-week-old muscle extracts and also declined with age. However, no significant changes in ODC or SAMDC activities were evident in any of the dystrophic muscle tissues studied when compared with their age-matched controls. Polyamine contents in dystrophic hamster myoblast and fibroblast primary cultures were also during proliferation (1 and 2 days after the initial seeding) compared with cultures prepared from normal hamsters. ODC and SAMDC activities in primary myoblast and fibroblast cultures clearly reflected the rate of cell proliferation, with highest activities found in subconfluent cell cultures. However, in general, no significant dystrophic-related abnormality in ODC or SAMDC activity was evident in proliferating myoblast or fibroblast cultures. These results suggest that the elevated polyamine contents of dystrophic hamster tissues and primary cultures may be due to a deficiency in polyamine catabolism or transport.

Adenosylmethionine Decarboxylase↗
PubMed1988

Prolonged anaesthesia with isoflurane and halothane. Effects on hepatic function.

Hepatic function was assessed pre-operatively and on the first and sixth postoperative days in 40 healthy patients who underwent prolonged maxillofacial surgery with isoflurane or halothane anaesthesia. No major changes were observed in hepatic enzymes or bilirubin. One-stage prothrombin time and Factor VII concentrations decreased on the first postoperative day and this change was more pronounced in the halothane group. The results support the use of isoflurane rather than halothane for prolonged anaesthesia in respect of the synthesising function of the liver.

Anesthesia, Inhalation↗
PubMed1986

Evaluation of two oxygen analyzers by computerized data acquisition and processing.

Monitoring of inspired oxygen concentration during anesthesia with nitrous oxide is becoming accepted as essential. This type of monitoring demands accurate monitors that respond rapidly. We evaluated two such devices for their response patterns to rapid changes in oxygen concentration, a galvanic or "fuel cell" unit and a polarographic device. Data were stored after analog-to-digital conversion. The response patterns to stepwise changes in nitrous oxide and oxygen mixtures were recorded at flow rates ranging from 2 to 10 L/min. Both units responded accurately to all changes in the absolute oxygen concentration; the polarographic unit was, on average, twice as fast. Responsiveness to nitrous oxide was low (less than 0.4% at 100% nitrous oxide), and the stability of the signals was good. The 90% response time (T90) was consistent for any stepwise increase or decrease in oxygen concentration between 0, 21, 33, 50, and 100%. After a step change from 0 to 100% oxygen at a gas flow rate of 10 L/min, the T90 was 5.8 seconds in the polarographic device and 11.4 seconds in the galvanic device (p less than 0.01). After a decrease from 100 to 0% oxygen, the T90 was 0.6 second longer in both monitors. Comparing flow rates of 2 L/min with 10 L/min, the T90 was delayed by 1.1 and 2.3 seconds for an increase, and by 1.4 and 2.9 seconds for a decrease in oxygen concentration. Experimental data suggest that both sensors respond adequately during routine clinical use. The faster response of the polarographic device is probably of limited clinical relevance, but it may aid in calibration.

Anesthesia, General↗