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Biomedical subjects

H Owen

Publications and source records attributed to H Owen.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1992

Oxyhaemoglobin saturation following elective abdominal surgery in patients receiving continuous intravenous infusion or intramuscular morphine analgesia.

Oxygen saturation was continuously measured using computerised pulse oximetry for 8 h overnight pre-operatively and for the first 24 h postoperatively in 40 patients receiving intermittent intramuscular morphine or continuous infusion of morphine following elective upper abdominal surgery. The proportion of time with an oxygen saturation less than 94% was used as an index of desaturation. Patients receiving continuous infusion analgesia received a larger morphine dose and achieved better analgesia than the intramuscular group. Postoperatively, the duration of desaturation increased 10-fold over pre-operative values, 'intramuscular' patients spending 39.0% (SD, 37.0%) and 'continuous infusion' patients 40.0% (SD, 37.5%) of the time below 94% saturation. Although newer therapies (e.g. epidural analgesia and patient-controlled analgesia) are currently receiving greater attention, the sequelae of these more traditional analgesic techniques warrant further study.

Abdomen↗
PubMed1992

An automated system for testing the accuracy of patient-controlled analgesia devices.

A system was developed to test the accuracy of patient-controlled analgesia devices in situations simulating clinical use. Bolus requests are made automatically at predetermined intervals, and the infusate delivered is measured and recorded without the need for operator presence. To ensure clinical relevance, the bolus request times used in this study corresponded to a pattern typical of those requested by patients on the ward. Graseby, Abbott Provider 5500 and IVAC patient-controlled analgesia devices were tested and found to deliver reasonably accurately over a 24 h period. However, when an infusion was started in an unprimed system or after a period of no bolus requests in a bolus-only mode the Graseby and IVAC machines under-delivered. This system provides a means of testing patient-controlled analgesia devices operating in any delivery mode.

Analgesia, Patient-Controlled↗
PubMed1991

Assessment of antinociceptive drug effects in the presence of impaired motor performance.

The hot-plate (HP) and tail-flick (TF) tests are widely used to assess analgesic activity of drugs. These tests do not directly measure the intensity of the noxious stimulus perceived by the animal, but only the animal's response to it, and so may be affected by non-analgesic drugs. Sedatives and muscle relaxants, for example, may impair the ability to respond and hence be wrongly considered to have analgesic activity. We examined response of rats in the HP (55 degrees C, cutoff time 25 sec) and TF (cutoff time 5 sec) tests following administration of pentobarbitone, diazepam or pancuronium. These drugs all impaired motor performance as assessed by reduction in mean rotarod performance times to 6-32% of predrug values. However, HP and TF latencies were not appreciably prolonged. We also found that pancuronium did not alter effects of morphine on HP or TF latencies, despite reduction in rotarod performance to 38% of predrug values. Our results support the validity of HP and TF tests as analgesic assays even in the presence of substantial impairment of motor performance.

Analgesics↗
PubMed1991

Premedication: an audit.

A prospective study of routine premedication management was carried out at a large teaching hospital. Many patients received their premedication at times inappropriate for it to be effective. Several patients receiving regular medication had this suddenly stopped pre-operatively. Prolonged fasting occurred in both elective and emergency groups of patients. Benzodiazepines and opioids were prescribed most frequently and drying agents were used widely. Antacids, H2-blockers and agents to promote gastric emptying were used very little despite the potential of aspiration in many groups of patients. This audit of activity has revealed several areas of practice that can either be improved immediately or warrant detailed investigation.

Adolescent↗
PubMed1991

Peri-operative drug prescribing pattern and manufacturers' guidelines. An audit.

Many patients admitted for surgery are receiving regular drug therapy. Adverse effects may occur, either as a result of these drugs being stopped suddenly or because staff are unaware of significant interactions between certain drugs and anaesthetic agents or techniques. This study aimed to find out how regular drug medication is actually given in the peri-operative period. In addition, pharmaceutical companies were contacted and asked for information about the effects of sudden withdrawal of their products and potential interactions with anaesthetic agents. We found that many drugs were omitted peri-operatively with potentially significant effects. Pharmaceutical companies do not seem to appreciate the importance of this problem and not all of them give clear recommendations relevant to practising anaesthetists.

Anesthesia↗
PubMed1991

Assessment of a new infusion pump for epidural PCA.

The use of epidural fentanyl by patient-controlled analgesia (PCA) may be a useful method of providing high-quality postoperative analgesia on the general surgical ward. The successful use of this technique requires an infusion pump with specific characteristics. Three Provider 5500, newly-developed, battery-powered PCA pumps, were tested to determine their accuracy, threshold of occlusion alarm limits and stored volume characteristics. These measurements were repeated following the in-line addition of an 18 gauge epidural catheter and two 0.2 micron filters. Pumps delivered on average within 3% of stated infusion rates and within 3% of bolus dose size. Occlusion pressures generated were between 1200 and 1360 mmHg, while the mean stored volume was 0.12 ml. Accuracy of delivery was maintained at lower voltage inputs. Addition of the catheter failed to alter the accuracy of the pumps tested. Siphoning of fluid was possible on disconnection of cartridge from pump. This problem did not occur with the addition of an epidural catheter and filter. This device has features which make it suitable for the safe delivery of epidural PCA. Care, however, needs to be taken on changing cartridges to prevent accidental administration of a drug bolus to the patient.

Analgesia, Patient-Controlled↗
PubMed1991

The influence of rectal cisapride on morphine-induced gastric stasis.

The effect of a new formulation of the gastric prokinetic agent cispride on opioid-induced gastric stasis was investigated. Forty patients were randomly allocated to one of four therapies administered as premedication; group A, placebo suppositories only; group B, placebo suppositories and intramuscular morphine 10 mg; group C, rectal cisapride 30 mg and intramuscular morphine 10 mg and group D, rectal cisapride 60 mg and intramuscular morphine 10 mg. Gastric emptying was assessed from the small bowel absorption of paracetamol following oral absorption. The kinetics of the suppository formulation were determined from venous blood samples. Rectal cisapride in the two doses used did not prevent opioid-induced gastric stasis. This may reflect an inability of this formulation to produce adequate plasma concentrations.

Acetaminophen↗
PubMed1991

Patient-controlled analgesia: can it be made safer?

Patient-controlled analgesia (PCA) has been shown to provide superior pain relief when compared with standard therapy options for postoperative analgesia. If PCA is to be implemented widely in teaching, private and country hospitals, its effectiveness needs balanced with a high safety profile. This can be achieved by consideration of patient selection, comprehensive education of patients, medical and nursing staff and equipment familiarisation. Continuous clinical audit allows identification of problem areas along with monitoring analgesic efficacy.

Analgesia, Patient-Controlled↗
PubMed1991

Variation in the blood concentration/analgesic response relationship during patient-controlled analgesia with alfentanil.

The effect of supplementing postoperative patient-controlled analgesia (PCA) with a mandatory fixed-rate infusion was studied using alfentanil. Patients were assigned by lottery to receive alfentanil PCA with a bolus of 200 or 300 mcg or alfentanil PCA with a bolus of 100 or 200 mcg plus an infusion of 900 mcg/hr, such that ten patients received each treatment. Seven patients receiving PCA only, compared to two in the groups receiving infusion, were withdrawn due to inadequate pain relief (0.1 greater than P greater than 0.05). One patient receiving PCA only was withdrawn because of a low respiratory rate, whereas three patients receiving PCA plus infusion developed respiratory depression. Patients prescribed PCA plus infusion received significantly more alfentanil but did not describe less pain than patients prescribed PCA only. The blood alfentanil concentration immediately prior to demands was significantly higher in the PCA plus infusion groups. These results suggest that during PCA therapy the drug prescription influences the blood concentration associated with satisfactory analgesia.

Abdomen↗
PubMed1990

Differing effects of pethidine and morphine on human sphincter of Oddi motility.

The aim of this study was to evaluate the effects of morphine and pethidine on human sphincter of Oddi motility. The action of these opioids on the sphincter of Oddi was evaluated by means of intraoperative manometry in 36 patients undergoing elective cholecystectomy. Both opioids were given in intravenous cumulative equipotent doses up to a maximum of 10 micrograms/kg morphine or 100 micrograms/kg pethidine. At these doses, morphine increased the mean(s.d.) frequency of contractions from 2.4(1.0) to 7.9(1.6) (P less than 0.001); this effect was reduced by naloxone (0.04 mg bolus, P less than 0.05). Pethidine inhibited the frequency of contractions from 1.5(0.8) to 0.8(0.5) (P less than 0.05); this response was blocked by atropine (0.6 mg bolus, P less than 0.01). Pretreatment with atropine or naloxone reduced the frequency of contractions significantly (P less than 0.05). The results illustrate different responses to pethidine and morphine of the sphincter of Oddi, and provide a pharmacological explanation for the suitability of pethidine over morphine as the analgesic of choice in patients experiencing biliary pain.

Adult↗
PubMed1990

PCA or PAA?

Explore the source record for details and available documents.

Analgesics↗
PubMed1990

Variables of patient-controlled analgesia. 3: Test of an infusion-demand system using alfentanil.

Patient-controlled infusion-demand analgesia was studied using alfentanil. We were unable to identify an optimal dose and administration rate; doses required range from 100 to 900 micrograms alfentanil. The mean concentration of alfentanil in blood associated with return of pain (i.e. immediately before demand) was 58 ng/ml on day 1 and 37 ng/ml on day 2. This difference was despite similar drug consumption on both days.

Adolescent↗
PubMed1990

Variables of patient-controlled analgesia 4: the relevance of bolus dose size to supplement a background infusion.

A range of self-administered demand doses of morphine (0.4, 0.7 and 1.0 mg) were prescribed to supplement a fixed-rate infusion (1.5 mg/hour) for pain control after gynaecological surgery. The number of demand doses administered during the first 25 hours after surgery was not significantly influenced by size of demand dose. There was a significant linear trend to increasing amount of demanded morphine with increasing bolus size. These results cast doubt on the usefulness of the concept of a minimum effective analgesic concentration of morphine.

Adult↗