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Biomedical subjects

R C Hutchinson

Publications and source records attributed to R C Hutchinson.

13 recordsLinked to original sources
PubMed2001

Patient-maintained sedation for ERCP with a target-controlled infusion of propofol: a pilot study.

BACKGROUND: ERCP requires patient cooperation and often prolonged sedation. In different areas of anesthetic practice, patient-controlled sedation with a target-controlled infusion (TCI) of propofol provides effective sedation. The aim of this study was to assess the safety and efficacy of the same system in patients undergoing ERCP. METHODS: Twenty patients used the TCI system. Patients received oxygen at 2 L/min via nasal cannulae. By using pharmacokinetic TCI software modeling, an initial propofol target blood concentration (Ct) of 1.0 microg/mL was supplemented on patient demand with a handset that, when pressed twice within 1 second, increased the Ct of propofol by 0.2 microg/mL. The maximum permissible target concentration was set at 3.0 microg/mL to prevent oversedation. RESULTS: Sixteen patients used the system successfully throughout the procedure. The Ct propofol ranged from 1.2 to 2.6 microg/mL, and the number of successful handset activations (after commencement of the ERCP) ranged from 0 to 3. In 3 patients, the ceiling Ct propofol was attained without adequate sedation and the system was manually overridden. The system failed in 1 case because of patient confusion. There were no episodes of hemodynamic instability, airway obstruction, or significant oxygen desaturation. Endoscopist and patient satisfaction were high. Four patients were oversedated according to our criteria at the end of the procedure, but all were awake within 5 minutes of arrival in the recovery area. CONCLUSIONS: Patient-maintained sedation with TCI propofol was safe and fully effective in 16 patients. Ease of endoscopy was rated high by the endoscopists, and all patients were well satisfied with their sedation. Adjustments to the software programming are being evaluated to increase the safety profile to avoid oversedation.

Adult↗
PubMed2000

Sedation for endoscopy.

A review of the recent literature reveals an increasing published opinion in favour of unsedated endoscopy. However, recent studies show that the majority of US patients are unwilling or unable to tolerate this. In order for there to be a shift towards unsedated endoscopy, physicians will have to change patients' expectations. The indications for diagnostic and therapeutic endoscopic procedures continue to expand, involving increasingly complex techniques that require a high degree of patient cooperation. There is still a need to refine the sedative regimen for these cases.

Journal Article↗
PubMed1996

The Streptomyces peucetius drrC gene encodes a UvrA-like protein involved in daunorubicin resistance and production.

The drrC gene, cloned from the daunorubicin (DNR)- and doxorubicin-producing strain of Streptomyces peucetius ATCC 29050, encodes a 764-amino-acid protein with a strong sequence similarity to the Escherichia coli and Micrococcus luteus UvrA proteins involved in excision repair of DNA. Expression of drrC was correlated with the timing of DNR production in the growth medium tested and was not dependent on the presence of DNR. Since introduction of drrC into Streptomyces lividans imparted a DNR resistance phenotype, this gene is believed to be a DNR resistance gene. The drrC gene could be disrupted in the non-DNR-producing S. peucetius dnrJ mutant but not in the wild-type strain, and the resulting dnrJ drrC double mutant was significantly more sensitive to DNR in efficiency-of-plating experiments. Expression of drrC in an E. coli uvrA strain conferred significant DNR resistance to this highly DNR-sensitive mutant. However, the DrrC protein did not complement the uvrA mutation to protect the mutant from the lethal effects of UV or mitomycin even though it enhanced the UV resistance of a uvrA+ strain. We speculate that the DrrC protein mediates a novel type of DNR resistance, possibly different from the mechanism of DNR resistance governed by the S. peucetius drrAB genes, which are believed to encode a DNR antiporter.

Adenosine Triphosphatases↗
PubMed1993

Severe pulmonary oedema after venous air embolism.

We present a 59-yr-old Chinese male patient who developed acute pulmonary oedema and cardiovascular collapse following multiple episodes of venous air emboli while in the sitting position for removal of a cervical meningioma. The severity of the pulmonary oedema and cardiovascular disturbance were surprising. Postoperative ventilation and inotropic support were required and five litres of plasma were needed to replace the fluid lost as pulmonary oedema. We discuss the differential diagnosis of the pulmonary changes and review current ideas on the pathogenesis for pulmonary oedema following venous air embolism.

Carbon Dioxide↗
PubMed1993

The Sprotte needle and post dural puncture headache following caesarean section.

One hundred and forty-four patients receiving subarachnoid anaesthesia for caesarean section were prospectively analysed for quality of anaesthesia and the occurrence of post dural puncture headache (PDPH). Anaesthesia was administered via 24 gauge Sprotte (n = 104) and 26 gauge Quincke (n = 40) needles using hyperbaric bupivacaine 0.5% with morphine 0.2 mg. Anaesthesia was successful in 103 patients with the Sprotte needle and 38 patients with the Quincke needle, and the operating conditions were considered to be excellent. Of the 104 patients in the Sprotte needle group there were ten with PDPH (9.6%), two of which were considered severe. Of the 40 patients in the Quincke needle group there were eight with PDPH (20%), three of which were considered severe. Despite the lower incidence of headache in the Sprotte needle group, this was not statistically significant (P > 0.05), due to the difference in population size. We conclude that the 24 gauge Sprotte needle is associated with a comparatively low but clinically relevant incidence of headache in the obstetric population.

Adult↗
PubMed1992

Effect of dobutamine on oxygen supply and uptake in healthy volunteers.

We have measured the changes in VO2 and the VO2:DO2 relationship during infusion of dobutamine in healthy volunteers. Nine healthy, adult, non-obese, male physicians were infused with an incremental infusion of dobutamine starting at 2.5 micrograms kg-1 min-1 increasing to 5.0 and then 7.5 micrograms kg-1 min-1 for 15 min each. VO2 and cardiac index were measured every five minutes. VO2I (VO2m-2) increased from a baseline of 128 (SEM 6.1) ml min-1 m-2 to 159 (8.0) ml min1 m-2 (P < 0.05) at the end of infusion with 7.5 micrograms kg-1 min-1. The corresponding changes for DO2I (DO2 m-2) were from 643 (35) ml min-1 m-2 to 1240 (142) ml min-1 m-2 (P < 0.05). The coefficient of correlation for pairs of VO2 and DO2 values, at baseline and each dobutamine infusion in individual subjects, ranged from 0.89 to 0.99 (mean 0.95, SD 0.03). Dobutamine has potent calorigenic effects; demonstration of a positive correlation between VO2 and DO2 after infusion of dobutamine does not necessarily imply an underlying tissue oxygen debt.

Adult↗
PubMed1991

Plasma catecholamines and oxygen consumption during weaning from mechanical ventilation.

Previous studies on oxygen consumption (VO2) during weaning from mechanical ventilation assumed that an increase in VO2 (delta VO2) reflected oxygen consumption by respiratory muscles (VO2RESP), and proposed delta VO2 as a weaning predictor. We measured VO2 CO2 production (VCO2) and plasma catecholamines in 20 short-term ventilated patients during weaning by SIMV and CPAP. delta VO2 as a percentage of VO2 during spontaneous ventilation (delta VO2%) ranged from 4.8% to 41.5%. VCO2 also increased and correlated with VO2. Plasma adrenaline and noradrenaline increased significantly to levels known to produce considerable increases in metabolic rate. Mean arterial pressure and heart rate concomitantly increased, but spontaneous minute ventilation decreased. Thus, since the increased plasma catecholamines are calorigenic, the assumption that delta VO2 represents VO2RESP is incorrect. Although mean delta VO2% of successfully weaned patients was significantly less than that of failure-to-wean patients, the wide scatter of individual values in the latter group excludes delta VO2% as an accurate weaning predictor.

Adult↗
PubMed1991

Systems analysis applied to intracranial pressure waveforms and correlation with clinical status in head injured patients.

Intracranial pressure waveforms (ICPWF) in head injured patients vary with the nature and severity of injury. Clinical interpretation of ICPWF shape is not defined. Spectral analysis provides an objective method of measuring changes in waveform shape, but the indices most suitable for clinical use remain unknown. Spectral analysis has been applied to ICPWF recorded from 30 patients with head injury, classified on clinical grounds into good, poor and intermediate groups. Normalized indices derived from ratios of certain characteristics of the ICP waveform to those of the arterial pressure (AP) waveform, were different (P less than 0.05) in all groups. A simple index examined was the harmonic count ratio (Nc:Na) which decreased with increasing severity of injury. ICP/AP harmonic transfer functions were derived, and demonstrated a peaked response in the range 10-12 Hz. Increasing attenuation of this peaked response occurred with increasing severity of injury. These results suggest that transfer functions may be a clinically useful index of intracranial conditions.

Blood Pressure↗
PubMed1984

Anaesthesia for Shy-Drager syndrome.

Anaesthesia for nephrectomy in a patient with Shy-Drager syndrome is described. The potential problems and pre-, per- and postoperative management are discussed with particular reference to the monitoring of cardiovascular function by pulmonary artery catheterisation.

Aged↗