PubMed Health⌕ Search

Biomedical subjects

M S McKinney

Publications and source records attributed to M S McKinney.

7 recordsLinked to original sources
PubMed1998

Cardiovascular effects of 50% nitrous oxide in older adult patients anaesthetized with isoflurane or halothane.

We have studied the cardiovascular effects of equipotent concentrations of halothane or isoflurane, with or without 50% nitrous oxide in oxygen, in 80 patients, aged 60 yr or more, during 20 min of stable equipotent anaesthesia. Non-invasive measurement techniques were used, with suprasternal Doppler ultrasonography for estimating cardiac output. Both isoflurane and halothane reduced heart rate and systemic arterial pressure. With isoflurane, mean rate decreased from 72 (SD 9.7) to 67 (10.4) beat min-1 and with halothane from 76 (10.1) to 65 (9.1) beat min-1 (P < 0.05). Mean diastolic arterial pressure decreased from 81 (11.3) to 58 (17.0) mm Hg with isoflurane and from 86 (14.7) to 70 (13.3) mm Hg with halothane (P < 0.05). Cardiac index decreased from 3.1 (1.03) to 2.7 (0.71) litre min-1 m-2 with isoflurane and from 3.1 (0.98) to 2.5 (0.57) litre min-1 m-2 with halothane (P < 0.05). Systemic vascular resistance decreased significantly in all groups except those receiving halothane with nitrous oxide. Nitrous oxide resulted in significantly less depression of cardiac index when given with isoflurane than when given with halothane. The mean percentage change in cardiac index during isoflurane anaesthesia without nitrous oxide was 16.7%; with nitrous oxide there was a 0.5% increase. Halothane, in combination with nitrous oxide, resulted in greater depression of cardiac index than isoflurane with nitrous oxide. The mean percentage change with halothane was 20.4% (22.2%); with isoflurane there was a 0.5% (27.1%) increase (P < 0.05). Hypotension was more pronounced in patients anaesthetized with isoflurane (n = 40) than those anaesthetized with halothane (n = 40), irrespective of the presence of nitrous oxide. The mean percentage decrease with isoflurane was 29.7% (21.10%) compared with 16.8% (16.78%) with halothane (P < 0.05).

Age Factors↗
PubMed1993

Cardiovascular effects of isoflurane and halothane in young and elderly adult patients.

We have studied the cardiovascular effects of 1 MAC end-tidal concentrations of halothane and isoflurane in young (n = 40) and elderly (n = 40) adult patients using non-invasive techniques. Cardiac output was measured by Doppler ultrasonography. Halothane reduced heart rate, systolic, mean and diastolic arterial pressures and cardiac index in both age groups (P < 0.05). Isoflurane reduced systolic, mean and diastolic arterial pressures also, but reduced cardiac index and heart rate only in the older patients (P < 0.05). Halothane depressed cardiovascular state significantly more than isoflurane in the younger adults (P < 0.05), but cardiovascular depression was similar for the two agents in the older age group. The decreases in systolic and diastolic pressures in the older patients were significantly greater with isoflurane compared with halothane (P < 0.05).

Adult↗
PubMed1990

Effect of flumazenil on midazolam-induced amnesia.

We have studied the effect of i.v. flumazenil 0.01 mg kg-1 on the amnesia and sedation caused by midazolam 2 mg and 5 mg i.v. in volunteers in order to determine the relationship between the actions of the antagonist on these two effects. Midazolam caused dose-dependent central neural depression as assessed by critical flicker fusion frequency, and dose-dependent amnesia for word cards. In subjects given flumazenil 5 min after administration of midazolam, fusion frequency readings and memory were restored to levels comparable to those before midazolam administration. These two effects of flumazenil were similar in time course and extent, suggesting that they share the same mechanism of action. Flumazenil given alone had no effect on memory. The study has demonstrated anterograde amnesia following benzodiazepine administration and antagonism by flumazenil. There was neither retrograde amnesia nor retrograde antagonism of amnesia.

Adult↗
PubMed1990

Diclofenac for day-care arthroscopy surgery: comparison with a standard opioid therapy.

Sixty unpremedicated patients presenting for day-care arthroscopy surgery were allocated randomly to receive diclofenac 1 mg kg-1 i.m., fentanyl 1 microgram kg-1 i.v. or no analgesic during the course of anaesthesia. Patients receiving fentanyl had slightly, although not significantly prolonged recovery times. Patients receiving diclofenac had significantly improved postoperative visual analogue pain scores compared with patients receiving placebo medication (P less than 0.05). With fentanyl, pain scores were reduced also, but the effect was not statistically significant. Both fentanyl and diclofenac produced significant reduction in postoperative analgesic requirements (P less than 0.05). We conclude that diclofenac 1 mg kg-1 i.m. was an effective analgesic for arthroscopic procedures on the knee and is a useful alternative to opioids for day-care patients.

Adolescent↗
PubMed1989

Characteristics of the Pharmaseal continuous flushing device.

Pharmaseal continuous flushing devices were tested with regard to flow characteristics into simulated arterial and venous pressure systems. Two driving pressures were used and it was found that variation in driving pressure made a significant difference to the flow, while arterial or venous pressure made no significant difference. The flow devices had a wide variation although they were all of the same type. The fluid volume delivered was in the region of 100 ml in a 24-hour period.

Equipment Design↗