Biomedical subjects

J L Plummer

Publications and source records attributed to J L Plummer.

At least 37 records · Page 2Linked to original sources

PubMed1996

A comparison of variable-dose patient-controlled analgesia with fixed-dose patient-controlled analgesia.

We examined the effect on the quality of analgesia and side effects of increasing the patient control component of morphine patient-controlled analgesia (PCA) by offering the patient a choice of bolus dose sizes. Using a three-button hand piece, patients could choose between 0.5-, 1.0-, and 1.5-mg boluses of morphine (variable-dose PCA, VDPCA). Successful demands were delivered by a modified Graseby 3400 Anaesthesia Pump controlled by a Toshiba T1900 computer. This system was compared with conventional fixed-dose PCA (FDPCA) (1.0 mg of morphine) delivered by a Graseby 3300 PCA Pump. Both treatment groups had a 5-min lockout interval. Sixty patients were randomly assigned to receive either VDPCA or FDPCA after major abdominal gynecological surgery or hip or knee arthroplasty. Treatment groups did not differ in their duration of PCA therapy, total morphine consumption, or time spent with mild or severe oxyhemoglobin desaturation. There were no differences in their ease of controlling pain, satisfaction with pain control, experience of pain on movement, quality of sleep, severity of nausea, or incidence of vomiting. Although the more complex VDPCA technique provides adequate postoperative analgesia, it does not offer any advantage over conventional FDPCA.

Adult↗

PubMed1995

Behavioural effects of norpethidine, a metabolite of pethidine, in rats.

This study investigated behavioural effects of the toxic pethidine metabolite, norpethidine, in rats and its interactions with reserpine, apomorphine and physostigmine. Following intraperitoneal administration, brain concentrations of norpethidine reached a plateau after 20-40 min and remained elevated for 2 h. In the dose range 0.06-0.18 mmol/kg, norpethidine induced myoclonic jerks, a characteristic splayed posture, and episodes of exaggerated shivering. Forward locomotion, grooming, yawning and rearing were suppressed. Seizures and reverse locomotion occurred occasionally. Administration of reserpine 1 h prior to norpethidine, or of apomorphine or physostigmine 15 min after norpethidine, did not alter the norpethidine-induced behaviours; neither did norpethidine block the effects of apomorphine or physostigmine. The characteristic profile of behaviours induced by norpethidine make this toxicant readily amenable to animal studies. Our results indicate that its mechanism of action is unlikely to involve dopaminergic or cholinergic pathways.

Animals↗

PubMed1995

Development of tolerance to antinociceptive effects of an intrathecal morphine/clonidine combination in rats.

Previous animal studies have shown the antinociceptive effects of intrathecal clonidine and intrathecal morphine to be synergistic. This study investigated the intrathecal administration of multiple doses of this drug combination to examine the rate of development of tolerance and to determine whether there was any toxic effect on the spinal cord. Rats with indwelling intrathecal catheters were given saline, morphine (2.5-7.5 micrograms), clonidine (17.5 micrograms), or clonidine (17.5 micrograms) plus morphine (1 microgram) intrathecally twice daily for 4 1/2 days (total of 9 doses). Hot plate and tail flick tests were conducted after the first, fifth and ninth doses. After the ninth dose animals were killed and their spinal cords were removed for histological examination. Tolerance developed to the antinociceptive effects of the drug combination, but at a slower rate than to morphine alone. No evidence of toxicity or injury to the spinal cord was observed other than changes which could be ascribed to the presence of the catheter.

Animals↗

PubMed1995

Evaluation of the influence of movement on saturation readings from pulse oximeters.

This study aimed to develop a protocol for assessing the influence of movement on oxyhaemoglobin saturation readings from pulse oximeters. Thirty-six volunteers took part in the study. In each volunteer, each hand was monitored by both a Nellcor N200 oximeter using a disposable probe and by a Datex Satlite DS103 oximeter using a clip-on finger probe. Volunteers made five standardised movements during which output was recorded from all four oximeters. All movements were associated with apparent decreases in oxyhaemoglobin saturation which were statistically significant for two movements with the Nellcor equipment and for four movements with the Datex equipment. Movement was associated with increases in the magnitude of pulse amplitude, but this was not quantitatively associated with magnitude of artefactual changes in saturation. Use of this standardised movement protocol allows quantification of movement artefact from pulse oximeters and should facilitate the development of equipment less affected by movement.

Adolescent↗

PubMed1995

The introduction of patient-controlled analgesia into an isolated rural hospital.

This study investigated the feasibility of using patient-controlled analgesia (PCA) effectively in a small 70 bed isolated rural hospital. The first 50 patients to use a Bard PCA 1, in the Port Lincoln Hospital, South Australia, were studied. The patients consumed morphine at a mean rate of 1.24 mg/h and used PCA for a mean of 48 h. Thirty-eight per cent of patients required treatment for nausea and other complications which is similar to the rate of those in other published series. Visual analogue pain scores showed excellent pain control, generally without evidence of oversedation; however, there was one episode of respiratory depression. Seventy-eight per cent of patients reported that their pain was relieved most or all of the time. The study demonstrated that a PCA service provided by nursing staff, the GP anaesthetist and rural surgeons is feasible in an isolated rural hospital.

Adult↗

PubMed1995

A double-blind randomized controlled trial of ginger for the prevention of postoperative nausea and vomiting.

The efficacy of ginger for the prevention of postoperative nausea and vomiting was studied in a double-blind, randomized, controlled trial in 108 ASA 1 or 2 patients undergoing gynaecological laparoscopic surgery under general anaesthesia. Patients received oral placebo, ginger BP 0.5g or ginger BP 1.0g, all with oral diazepam premedication, one hour prior to surgery. Patients were assessed at three hours postoperatively. The incidence of nausea and vomiting increased slightly but nonsignificantly with increasing dose of ginger. The incidence of moderate or severe nausea was 22, 33 and 36%, while the incidence of vomiting was 17, 14 and 31% in groups receiving 0, 0.5 and 1.0g ginger, respectively (odds ratio per 0.5g ginger 1.39 for nausea and 1.55 for vomiting). These results were essentially unchanged when adjustment was made for concomitant risk factors. We conclude that ginger BP in doses of 0.5 or 1.0 gram is ineffective in reducing the incidence of postoperative nausea and vomiting.

Adjuvants, Anesthesia↗

PubMed1995

The effect of oral cisapride premedication on fasting gastric volumes.

The aim of this study was to determine whether fasting gastric volumes could be reduced by preoperative administration of cisapride. One hundred and twenty-one patients undergoing elective general anaesthesia were randomly allocated to receive either cisapride 20 mg plus diazepam 10 mg or placebo tablets plus diazepam 10 mg, two hours prior to induction. Immediately following induction blind gastric aspiration was performed using a 16Fr multiorificed orogastric tube. Gastric volume, pH, and cisapride blood concentration were measured at this time. Gastric volumes were significantly smaller in the cisapride group, 20.5 (SD 22.2) ml compared to placebo 28.2 (SD 26.0) ml but there was no significant difference with respect to pH. Some patients in both groups had large gastric volumes despite fasting. No significant adverse effects were noted with cisapride.

Adjuvants, Anesthesia↗

PubMed1994

Pharmacokinetics of bupivacaine enantiomers in sheep: influence of dosage regimen and study design.

Bupivacaine is used as a racemate. In previous studies the mean total body clearance of R(+)-bupivacaine was found to be greater than S(-)-bupivacaine by 65% after iv bolus dose of separate enantiomers and by 20% after iv infusion to steady state of racemate. The present studies were performed to determine whether different study designs using different iv dosage regimens could influence the pharmacokinetic parameters determined for either bupivacaine enantiomer. rac-Bupivacaine.HCl was administered iv to 6 adult Merino ewes by bolus, brief infusion, and prolonged infusion. Arterial blood concentrations of R(+)- and S(-)-bupivacaine were measured by enantioselective HPLC. These regimens consistently produced lower arterial blood concentrations of R(+)-bupivacaine than S(-)-bupivacaine due to R(+)-bupivacaine having a greater initial dilution volume by 16 (95% CI = 3-29)%, volume of distribution at steady state equilibrium by 32 (95% CI = 17-32)% and mean total body clearance by 28 (95% CI = 21-35)%. The slow half-life of R(+)-bupivacaine, however, was found to be 15 (95% CI = 0-31)% longer than that of S(-)-bupivacaine. The difference between enantiomers in mean total body clearance thus was similar to the previous study based upon infusion to steady state of rac-bupivacaine. Differences in pharmacokinetics attributable to the dosage regimen consisted of a greater mean total body clearance for R(+)-bupivacaine along with a smaller terminal half life with the bolus regimen and a longer half-life of S(-)-bupivacaine after prolonged infusion. Differences in pharmacokinetics between the bupivacaine enantiomers occurred consistently in both distribution and clearance but the magnitude of the effect was less than 50% in each case. Systematic differences in pharmacokinetics associated with the dosage regimen were found mainly in terminal half-life. Dosage regimen, thus, was found to influence the pharmacokinetic results found experimentally and is therefore a significant variable in its own right.

Anesthetics, Local↗

PubMed1994

A system for standardized evaluation of patient-controlled analgesia devices: design, construction, and engineering aspects.

OBJECTIVE: Our objective was to design, construct, and assess an automated system to perform standardized evaluation of patient-controlled analgesia (PCA) devices. METHODS: We developed a computer-controlled test station. The computer activates the PCA device under test through a purpose-built serial interface device. The dose delivered is weighed on an electronic balance; then, at a predetermined interval, the computer interrogates the balance via the serial interface device to determine the weight gain. A robotic digit simulates patient button presses for four commonly used demand mechanisms. Software programs were written to test three types of patient-demand profile. RESULTS: The automated system is sufficiently accurate for evaluating PCA devices and has been successfully used to perform and evaluate several thousand demands on six different models of PCA device. CONCLUSIONS: The test station has proved to be simple to use and extremely reliable, and has enabled the successful evaluation of several types of PCA device.

Analgesia, Patient-Controlled↗

PubMed1994

Alcohol/"low-dose" carbon tetrachloride-induced cirrhosis in rats using different methods of alcohol feeding.

Cirrhosis may be reliably produced in rats by exposing them to low levels of carbon tetrachloride vapor while feeding alcohol in the Lieber-DeCarli liquid diet. This study aimed to determine whether alternative cheaper and more convenient ways of feeding alcohol would also allow the production of cirrhosis. Animals were fed alcohol in the Lieber-DeCarli diet, in a gel diet, or by addition of alcohol + sucrose to their drinking water, and were exposed to carbon tetrachloride vapor 6 hr/night, 5 nights/week. After 12 weeks of treatment, all animals (4 of 4) receiving alcohol in the Lieber-DeCarli diet, but only two in each of the gel and drinking water groups, were cirrhotic. The variable results with the gel diet may be due to loss of alcohol by evaporation from the gel. Alcohol intake in the group receiving alcohol in drinking water was greater than in those receiving Lieber-DeCarli diet. We suggest that the increased carbohydrate intake due to addition to sucrose to the water exerted a protective effect on the liver.

Alcohol Drinking↗

PubMed1994

Dose-response relationships in hepatic injury produced by alcohol and carbon tetrachloride.

Dose-response relationships were examined for the production of hepatic fibrosis and cirrhosis by combined exposure of male Porton rats to alcohol and carbon tetrachloride. Alcohol was administered orally in Lieber-DeCarli liquid diet at levels of 75, 150, or 300 kcal/liter, giving mean daily intakes of 2.29, 4.61, and 8.16 g/kg/day, respectively. Carbon tetrachloride was administered by inhalation at concentrations of 10, 20, or 40 ppm, 6 hr/night, 5 nights/week. Liver biopsies were taken at intervals up to a maximum treatment period of 20 weeks. All four rats that received the high dose of both agents, and 1 of 4 that received the medium alcohol and high carbon tetrachloride treatments, were cirrhotic by 10 weeks. Two of the 4 rats that received the low alcohol and high carbon tetrachloride dose were cirrhotic at 20 weeks. Cirrhosis was not observed in rats that received the low or medium carbon tetrachloride dose, but some degree of hepatic fibrosis was observed in all treatment groups. Severity of fibrosis was significantly associated with both dose of alcohol and dose of carbon tetrachloride received. It is concluded that, in the alcohol-carbon tetrachloride rat model for chronic liver injury, both alcohol and carbon tetrachloride contribute to the response in a dose-related manner. Hepatic injury was observed even when relatively low doses of these agents are administered together.

Alcohol Drinking↗

PubMed1994

Changes in oxygen saturation in the 72 hours after hip surgery: the effect of oxygen therapy.

The aim of this study was to investigate changes in oxygen saturation (SpO2) occurring during the three days following hip surgery in patients in this hospital and to determine to what extent SpO2 might be improved by oxygen therapy for 24 or 72 hours. Eighty-three patients (aged 43-96 years) scheduled for elective total hip replacement or emergency surgery for hip fractures were studied. Forty-four patients had 24 hour postoperative oxygen prescribed by their anaesthetist or surgeon; we randomized these to either continue oxygen for a total of three days (Group 1) or to discontinue oxygen after Day 1 (Group 2). Patients not prescribed oxygen by the surgeon or anaesthetist (n = 39) were randomly assigned either to receive oxygen for three days (Group 3) or not to receive oxygen (Group 4). Oxygen was administered through nasal cannulae at a flow of 2 l.min-1. SpO2 was measured every 10 seconds for three days and stored on computer disc. Percentage of time spent with SpO2 below 90% was used as an index of desaturation. Patients receiving oxygen had significantly improved SpO2. In patients not receiving oxygen, desaturation was most severe on Days 1 and 2, improving somewhat on Day 3. On Day 2 desaturation was similar in Groups 2 and 4. When oxygen was not being administered males were significantly more desaturated than females. Our investigations indicate that following hip surgery poor saturation continues for at least two days and can be improved by oxygen therapy.

Adult↗

PubMed1993

A follow-up study on the effects of training on the fitness and habitual activity patterns of 60- to 70-year-old women.

This study investigated the aerobic fitness, body composition, spirometric variables, Human Activity Profile, and level of adherence to physical activity subsequent to completion of a progressive walking program of six month's duration (T1). Sixty-six women previously randomized to training (TG) and control (CG) groups were reassessed six months after finishing the six month walking program (T2). During the follow-up period, 77.8% of the TG subjects continued with exercise and maintained lower (p < 0.005) exercise heart rates compared to the CG. A Mann-Whitney U test on the difference scores (T2-T1) revealed no difference (p > 0.05) between the TG and CG for changes in Maximum Current Activity and Normative Impairment Index, which are both components of the Human Activity Profile, with the earlier increases (p < 0.05) in these parameters by the TG having been maintained. Participation in a previous low frequency training regimen therefore resulted in elderly women adopting and sustaining a higher level of habitual physical activity. This is important because a favorable modification of lifestyle factors is likely to be indicative of an enhanced outlook for independence.

Aged↗

PubMed1993

The effect of fentanyl administered epidurally by patient-controlled analgesia, continuous infusion, or a combined technique of oxyhaemoglobin saturation after abdominal surgery.

The aims of this study were to determine the effect of three different modes of epidural administration of fentanyl on oxyhaemoglobin saturation and pain control. Forty-three patients undergoing elective abdominal surgery were randomly allocated to the following groups: (1) continuous infusion of fentanyl at a rate of 50 micrograms.h-1 with additional epidural boluses (25 micrograms) as required; (2) patient-controlled analgesia using a 25 microgram epidural bolus of fentanyl with a 15 min lock-out period; (3) a combination of patient-controlled analgesia and continuous infusion. Oxyhaemoglobin saturation was measured by continuous computerised pulse oximetry for 48 h after operation together with pain and sedation scores. In the first 24 h after surgery patients in the continuous infusion group spent a significantly greater proportion of time below oxygen saturations of 94% and 85% than those in the other two groups. On day 2 all oxygen saturation measurements were worse than during day 1, but differences between groups were not significant. Those patients receiving patient-controlled analgesia required significantly less fentanyl than patients in either of the other groups (p < 0.05). However, the mean pain and sedation scores did not differ significantly between the three treatment groups. There was no association between total fentanyl dose and oxygen saturation values. Overall, self-administered fentanyl appeared to cause less oxyhaemoglobin desaturation than nurse-administered analgesia without any loss of analgesic effect.

Adolescent↗

PubMed1993

Perceived risks of postoperative analgesia.

This survey aimed to determine what type of information patients want about the risks of postoperative pain management and whether this corresponded to the information that doctors and nurses wished to provide. Seventy-four patients scheduled for elective surgery, 50 nurses and 48 doctors completed a questionnaire asking about perceived risks of analgesia, level of acceptable risk and information that should be provided to patients. Compared to doctors and nurses, patients underestimated the risks associated with postoperative pain relief, except for the risk of drug addiction, which they rated higher. Ninety-one per cent of patients wanted information about the side effects of analgesia. The preferred means of obtaining this information was by discussion with their surgeon or anaesthetist. Doctors were willing to accept a greater risk of minor side effects to achieve excellent pain relief than were patients. In contrast, patients were willing to accept a greater risk of serious side effects. The results obtained in this survey will facilitate the preparation of guidelines for obtaining informed consent from patients to receive postoperative analgesia.

Adult↗

PubMed1993

Background infusion with patient-controlled analgesia: effect on postoperative oxyhaemoglobin saturation and pain control.

The aim of this study was to determine whether the addition of a background infusion (BI) to patient-controlled analgesia (PCA) would lead to significantly improved pain control or poorer oxyhaemoglobin saturation (SpO2) after gynaecological surgery. Sixty-two patients were studied for 24 hours postoperatively; pain scores and morphine dose were recorded hourly, SpO2 was recorded every 10 seconds. Administration of the BI resulted in a significant increase in total morphine dose received although there was no difference in the severity of postoperative desaturation between the therapies. Despite the increased morphine dose pain scores also were similar in the two groups. Addition of a BI at 1 mg/hr did not confer any advantage over PCA alone and is not recommended when PCA is used in this patient group.

Adult↗

PubMed1993

Laboratory evaluation of the Go Medical PCI: a disposable patient-controlled analgesia device.

A low-cost, disposable patient-controlled analgesia device was tested using a computer-controlled, automated testing station designed to simulate clinical use. Five devices were tested and delivered a mean bolus dose size of 95% of nominal, although one device achieved only 85% of nominal. Delivery was lowest immediately following an eight-hour interval during which no demands were made. Further development and evaluation of this interesting device is warranted.

Analgesia, Patient-Controlled↗

PubMed1993

Laboratory evaluation of the Baxter Patient-Controlled Analgesia Infusor System: a disposable patient-controlled analgesia device.

The purpose of this study was to determine the accuracy of bolus-demand volumes obtained from the Baxter Patient-Controlled Analgesia Infusor System, a disposable patient-controlled analgesia device. An automated system was used to make demands in a pattern designed to simulate those made by a patient in the first 24 postoperative hours. Following this, a pattern of varying short interdemand intervals was used to evaluate performance of the device when demands were made near the nominal lockout interval of 6 min. Finally, a prolonged array of short interdemand intervals was used to evaluate performance as the reservoir of the devices became exhausted. Ten devices were tested. One device failed; after 70 min of testing the reservoir burst. The mean delivery of the remaining nine devices for the first 24 h of testing was 92.6% of nominal (SD = 3.9%). Evaluation near the nominal lockout interval revealed a departure of delivered volume from nominal (worst = 73.9% at an interdemand interval of 6 min). As the reservoir became exhausted, delivery increased to a maximum value, ranging from 118% to 137% of nominal, before falling to zero. In general, the devices performed consistently and the departures from nominal delivery were not considered to be of clinical significance.

Analgesia, Patient-Controlled↗