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Biomedical subjects

R J Ware

Publications and source records attributed to R J Ware.

9 recordsLinked to original sources
PubMed2001

Measurement of twitch transdiaphragmatic, esophageal, and endotracheal tube pressure with bilateral anterolateral magnetic phrenic nerve stimulation in patients in the intensive care unit.

OBJECTIVE: In the critically ill, respiratory muscle strength usually has been assessed by measuring maximum inspiratory pressure. The maneuver is volitional, and results can be unreliable. The nonvolitional technique of bilateral anterolateral magnetic stimulation of the phrenic nerves, producing twitch transdiaphragmatic pressure, has been successful in normal subjects and ambulatory patients. In this study we used the technique in the intensive care unit and explored the measurement of twitch endotracheal tube pressure as a less invasive technique to assess diaphragmatic contractility. DESIGN: Clinical study to quantify diaphragm strength in the intensive care unit. SETTING: Patients from three London teaching hospital intensive care units and high-dependency units. PATIENTS: Forty-one intensive care patients were recruited. Of these, 33 (20 men, 13 women) were studied. INTERVENTIONS: Esophageal and gastric balloon catheters were passed through the anaesthetized nose, and an endotracheal tube occlusion device was placed in the ventilation circuit, next to the endotracheal tube. Two 43-mm magnetic coils were placed anteriorly on the patient's neck, and the phrenic nerves were stimulated magnetically. MEASUREMENTS AND MAIN RESULTS: On phrenic nerve stimulation, twitch gastric pressure, twitch esophageal pressure, twitch transdiaphragmatic pressure, and twitch endotracheal tube pressure were measured. Forty-one consecutive patients consented to take part in the study, and twitch pressure data were obtained in 33 of these. Mean transdiaphragmatic pressure was 10.7 cm H2O, mean twitch esophageal pressure was 6.7 cm H2O, and mean twitch endotracheal tube pressure was 6.7 cm H2O. The mean difference between twitch esophageal pressure and twitch endotracheal tube pressure was 0.02 cm H2O. Correlation of the means of twitch endotracheal tube pressure to twitch esophageal pressure was 0.93, and that for twitch endotracheal tube pressure to transdiaphragmatic pressure was 0.78. CONCLUSIONS: Transdiaphragmatic pressure can be measured in the critically ill to give a nonvolitional assessment of diaphragm contractility, but not all patients can be studied. At present, the relationship of twitch endotracheal tube pressure to transdiaphragmatic pressure is too variable to reliably represent a less invasive measure of diaphragm strength.

Adult↗
PubMed1990

Mupirocin for the reduction of colonization of internal jugular cannulae--a randomized controlled trial.

In a prospective study, 218 cardiothoracic patients, in whom 'Abbocath-T' cannulae had been inserted preoperatively into the internal jugular vein, were randomized to receive skin preparation of the insertion site with tincture of iodine (108 controls) or tincture of iodine followed by application of sterile 2% calcium mupirocin ointment (110 test patients). Cannulae were usually removed within 48 h of the operation. Patients receiving mupirocin were less likely to develop significant colonization of one or more of their cannulae as judged by Maki's criterion of a yield of greater than 15 colony forming units (cfu) from a cannula segment rolled on an agar plate (17% of mupirocin treated patients compared with 54% of the controls, P less than 0.001). Coagulase-negative staphylococci, micrococci, or both, were the commonest isolates and were cultured from 70% of the 186 control cannulae compared with 24% of 172 cannulae inserted through mupirocin-treated skin (P less than 0.001). A count of more than 15 cfu was found on the tips of 25% control cannulae compared with 5% of the cannulae from mupirocin-treated patients, an effect which was independent of in-situ time (P less than 0.001). For cannulae with colonized tips, the same species was isolated from the skin of the insertion site in 67%, from the exterior of the hub in 61% and from the lumen in only 15%. There were no side effects attributed to mupirocin or superinfection with resistant organisms. We conclude that in cardiothoracic patients the application of mupirocin after standard skin preparation with tincture of iodine significantly reduces the colonization of central venous cannulae by organisms derived from the skin insertion site.

Adolescent↗
PubMed1987

Life threatening sickle chest syndrome treated with extracorporeal membrane oxygenation.

A young West Indian woman with established sickle cell disease developed a severe episode of sickle chest syndrome. Conventional treatment including exchange transfusions and mechanical ventilation was to no avail, and an infusion of epoprostenol also failed to halt her worsening condition. When her arterial oxygen tension (PaO2) had fallen to 6.5 kPa (49 mm Hg) extracorporeal membrane oxygenation was instituted. Within two days her PaO2 was greatly improved (maximum 11.6 kPa; 87 mmHg), and by the sixth day pulmonary vascular resistance was reduced and angiography showed reperfusion of many vessels. The patient recovered and six months later showed a transfer factor close to the predicted range and normal spirometric values. Extracorporeal membrane oxygenation should be considered for severe sickle chest syndrome when conventional methods of artificial ventilation fail.

Adult↗
PubMed1984

Pathways to complement activation during cardiopulmonary bypass.

Complement activation was assessed in 34 patients undergoing cardiopulmonary bypass. Arterial concentrations of complement fragments Ba and C3d rose in all patients, the increase in Ba preceding that of C3d. At the same time as complement fragments were being generated the arterial neutrophil count fell. These findings suggest (a) that complement activation is initiated by the alternative pathway during cardiopulmonary bypass and (b) that complement activation mediates loss of neutrophils during bypass. Complement mediated loss of neutrophils during the analogous setting of haemodialysis is the result of leucosequestration in the pulmonary vasculature. During cardiopulmonary bypass the lungs are out of circuit, so that activated leucocytes may sequester in other target organs. This may be an aetiological factor in the multi-organ failure occasionally seen after uneventful cardiopulmonary bypass.

Adult↗
PubMed1984

Closed loop control of vasoactive drug infusion. A preliminary report.

A closed loop control system for vasoactive drug infusion is described using a dedicated bedside microcomputer and a single volumetric infusion pump. The signal from an indwelling arterial cannula is taken from the bedside monitor through an analogue/digital converter to a microcomputer. After signal validation changes of infusion rate are calculated and communicated to a volumetric infusion pump through an RS 232 interface. The system has been successfully employed in four patients during cardiac surgery prior to cardiopulmonary bypass and in six cardiac surgical patients in the postoperative period. In both groups mean arterial pressure was controlled within 5 mmHg of target value for 75% of infusion time, and within 10 mmHg for 90% of the duration of infusion.

Analog-Digital Conversion↗
PubMed1979

Intravenous regional analgesia using bupivacaine. A double blind comparison with lignocaine.

A double-blind comparison of bupivacaine and lignocaine for intravenous regional analgesia (Bier's block) was carried out in seventy-two patients presenting for upper limb surgery. Thirty-eight patients received lignocaine and thirty-four received bupivacaine. Onset of analgesia and recovery times were similar for the two drugs. The degree of both analgesia and muscle relaxation was significantly better in the bupivacaine group. Adverse effects were seen only in patients who had received lignocaine and these were unrelated to the tourniquet time.

Anesthesia, Conduction↗
PubMed1975

Intravenous regional analgesia using bupivacaine.

Intravenous regional analgesia using bupivacaine (Marcain) was employed as the anaesthetic technique in a series of 50 cases undergoing a variety of surgical procedures on the upper limb. A short pilot study was undertaken to determine the optimal dosage and concentration of bupivacaine. This was found to be 1-5 mg/kg in 0-2% concentration and proved suitable for all patients regardless of age or physical condition. The use of bupivacaine produced highly successful results in 98% of cases. Onset of analgesia was very rapid (3-5 minutes) and profound muscular relaxation occurred in approximately half of the cases. The degree of muscle relaxation was, however, always adequate for the successful reduction of fractures. Only one patient exhibited an adverse reaction to the dose of bupivacaine used and this was limited to a brief period of slight drowsiness. The results of this series suggest that bupivacaine may provide advantages over previously used local analgesic agents for intravenous regional analgesia and that it may be the agent of choice for this useful technique.

Adolescent↗