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Biomedical subjects

H Owen

Publications and source records attributed to H Owen.

At least 73 records · Page 4Linked to original sources
PubMed1990

Antireflux valves in patient-controlled analgesia.

Antireflux valves are widely used in conjunction with patient-controlled analgesia devices. It is important to appreciate the limitations and dangers of these systems. They can achieve a potential 'stored volume' if occluded and they may, as part of the administration set, retard fluid administration. Seven antireflux systems currently available were tested in conjunction with three patient-controlled analgesia pumps. The systems' volume, time to occlusion alarm and flow rates were measured. Results showed that the sets with low stored volumes were less efficient as administration sets. A potentially dangerous bolus could result after release of occlusion if sets with large stored volumes were used in conjunction with pumps that utilised concentrated solutions of opioid. This study has identified the ideal antireflux valve system.

Analgesia, Patient-Controlled↗
PubMed1990

Patients' expectations of patient-controlled analgesia.

Patient-controlled analgesia is an increasingly popular method of postoperative pain relief. However, patients often worry about new therapies. Eighty ASA 1 and 2 patients aged 18-65 years were asked to list the advantages and disadvantages of using patient-controlled analgesia. The most important advantage as perceived by patients was the reduced time spent by nurses in giving medication, but there was concern that direct personal contact would also be lessened. Preservation of self control, autonomy, rapid onset of analgesia, ability to titrate analgesia and lack of injections were seen as an advantage. Addiction and machine faults were seen as minimal problems. Preservation of patient-nurse contact is of great importance to ensure success of postoperative analgesia.

Adolescent↗
PubMed1990

Rate-controlled analgesia: a laboratory evaluation of a new infusion device.

We report an evaluation of the Bard Harvard Mini Infuser, one of a new generation of agent-specific intraoperative infusion pumps which are designed for use by the anaesthetist. This pump permits potent intravenous anaesthetic agents to be used in pharmacokinetically designed dosage regimens. The controls are calibrated directly in kg body weight and micrograms per minute rather than the usual settings of ml of solution per hour. The performance was assessed by measuring the volume delivered over given time intervals and all safety functions were tested at least three times. This device was found to be acceptably safe and accurate. Two points to note are that it must be purged every time before it is connected to the intravenous infusion and if an occlusion is suddenly relieved, the patient can receive an 'accidental bolus' of up to 1.18 ml of drug. The main advantage of this pump is that it uses undiluted drug direct from the ampoule and does not require any calculations or dilutions prior to use. However, this restricts its use to drugs with a concentration of 500 mcg/ml and in effect means that it is suitable mainly for infusion of alfentanil.

Anesthesia, Intravenous↗
PubMed1989

Variables of patient-controlled analgesia. 1. Bolus size.

The efficacy of a range of demand doses of morphine for patient-controlled analgesia was studied. Patients who self-administered the smallest dose (0.5 mg) were frequently unable to achieve good pain control; patients who received the largest dose (2 mg) had a high incidence of ventilatory depression. A dose of 1 mg was the best increment under the conditions of this study but the relationship between increment and lockout interval requires consideration.

Abdomen↗
PubMed1989

Variables of patient-controlled analgesia. 2. Concurrent infusion.

The effectiveness of morphine after surgery by patient-controlled analgesia alone or with a concurrent infusion was studied. The infusion did not reduce the dose of self-administered analgesic and patients treated in this way received twice as much drug as those who used patient-controlled analgesia alone. Pain control was similar in both groups. The practice of patient-controlled analgesia plus infusion requires critical review.

Abdomen↗
PubMed1989

Narcotics in acute pain.

Opioids are the mainstay of therapy for acute pain for both medical and surgical conditions. An understanding of their actions and a basic knowledge of pharmacokinetics and pharmaceutical preparation will enable a doctor to optimise the treatment of acute pain. If the basic principles are taken into account there is no reason now to allow patients to be distressed by inadequate analgesia.

Acute Disease↗
PubMed1988

The scientific basis of patient-controlled analgesia.

The current practice of patient-controlled analgesia has grown from empirical observations. Although several variants of patient-controlled analgesia, bolus doses, infusions, or combinations of both, have been suggested, a scientific basis for advocating one variant over the others has been lacking. Most systems have been based on the simplest system, bolus demand, although the use of a combined bolus and background infusion method has theoretical merit. Similarly, a scientific basis for setting the variables of patient-controlled analgesia, drug choice, incremental dose, maximum dose and lockout interval, also has been lacking. Settings for these variables may be rationalised post hoc on the basis of the physicochemical properties and global pharmacokinetic properties of the opioids used but knowledge of these properties has not helped in setting the variables a priori. Foremost, the drug choice should be based on therapeutic index. Knowledge of the regional kinetics of drug (influx and efflux) from brain may provide a more logical basis for setting the patient-controlled analgesia variables but such information can only come from animal experiments. More research is required if patient-controlled analgesia is to become anything but an empirical tool in the quest for improved analgesia in patients.

Analgesia↗
PubMed1988

The development and clinical use of patient-controlled analgesia.

Patient-controlled analgesia has successfully made the transition from research tool to clinical acceptability. Reliable and sophisticated patient-controlled analgesia systems are commercially available. The technique has been most used for control of postoperative pain but has been successfully used during labour, after burns and other trauma and in terminal care. Virtually every opioid has been administered by patient-controlled analgesia using almost every route of administration. It is more effective than the traditional techniques of pain control after surgery but is not automatically so. Choice of opioid and the settings chosen for demand dose and lockout interval greatly influence effectiveness. Patient-controlled analgesia requires active participation by the patient but the psychology of patient-controlled analgesia has generally been under-estimated. Patient-controlled analgesia has developed empirically and many assumptions have been made; there is a need for fundamental research.

Analgesia↗
PubMed1987

Continuous extradural analgesia in labour. Comparison between "on demand" and regular "top-up" injections.

In a prospective comparative study 240 patients received extradural bupivacaine, either by regular timed injections or "on demand", for pain relief during the first stage of labour. Three concentrations of bupivacaine were used (0.5%, 0.375% and 0.25%). Quality and continuity of analgesia, motor blockade, spread of sensory blockade, cardiovascular changes, fetal outcome and maternal sequelae were recorded. Overall, the analgesia provided by regular top-up injections was superior to the on demand technique, especially when 0.375% bupivacaine was used. This improved analgesia was achieved without causing an increased incidence of operative deliveries or deleterious sequelae, with respect to the mother or the neonate.

Adult↗
PubMed1987

Analgesia from morphine and ketamine. A comparison of infusions of morphine and ketamine for postoperative analgesia.

Ketamine 4 micrograms/kg/minute produced pain relief similar to that from morphine 33 micrograms/minute in a double-blind study that compared analgesia from constant-rate intravenous infusions of the two drugs in 60 patients. The analgesic efficacy of the infusions, as assessed by pain scores and the requirement for supplementary self-administered morphine, was poor. Ventilatory depression, the most significant side effect, occurred only in patients who received morphine infusion. The low dose ketamine infusion did not provide clinically useful analgesia even though adequate plasma concentrations were achieved.

Clinical Trials as Topic↗
PubMed1987

Evaluation of gentamicin premixed admixtures: cost and clinical utility.

An objective of this study was to evaluate the cost effectiveness of employing gentamicin premixed admixtures compared to using exact, individualized compounded doses. Gentamicin use and waste data were collected over a 2-month period. Annualized institutional savings (300 beds) were projected to be $8,802. A second objective was to compare predicted to measured peak and trough serum gentamicin concentrations when premixed admixtures are used (rounding off computer generated doses to the nearest 10 mg) and when individually compounded exact doses are delivered. Twenty adults were randomized to receive premixed or compounded doses. Blood levels drawn at steady state were compared to predicted levels for the delivered dose. Differences between measured and predicted levels were not significant by performance of an independent t test on the mean square prediction errors. We conclude that it is cost effective and clinically valid to employ premixed intravenous admixtures in a large teaching hospital.

Adult↗
PubMed1986

Ibuprofen in the management of postoperative pain.

The effect of the regular administration of ibuprofen on pain following abdominal surgery was investigated in a double-blind placebo-controlled study. The analgesic action of ibuprofen was measured by a reduction in the amount of morphine self-administered from an On-Demand Analgesic Computer. Pain scores, nausea scores and blood loss were similar in both groups, but patients receiving ibuprofen demanded significantly less morphine in the 24 h after surgery.

Adult↗
PubMed1986

Microcomputer-based haemodynamic monitoring during continuous extradural analgesia.

A system for monitoring, recording and storing arterial pressure and heart rate during continuous extradural analgesia has been developed using an Apple II microcomputer and a Dinamap 1846 non-invasive arterial pressure monitor. The administration of local anaesthetic (or vasopressor) was recorded using a light pen. The computer was programmed to recognize this, and to initiate automatically more frequent measurements of heart rate and arterial pressure. The results of a study using this equipment are reported. The commands for computer control of the Dinamap 1846 are described.

Adult↗