The inflatable wedge: an aid to bilateral hip arthroplasty.

A reusable inflatable wedge system is described for use during bilateral hip arthroplasty. It allows rapid repositioning during the procedure, with minimal interference to the surgical field. It is robust, cheap and provides minimal compromise to surgical asepsis. It has potential for use in a variety of procedures.

Triple-lumen catheters.

Triple-lumen intravenous catheters have been available in the UK for 5 years. They are very useful for simultaneous monitoring and multiple infusion therapy. They are not difficult to insert using standard techniques and their use will probably increase. At the moment there are seven products on the British market, with a range of lumen sizes, special features and prices.

Haemodynamic effects of a prolonged infusion of propofol as a supplement to nitrous oxide anaesthesia. Studies in association with peripheral arterial surgery.

The haemodynamic effects of propofol at two infusion rates (54-65 and 108-130 micrograms kg-1 min-1) have been studied during peripheral arterial surgery in eight elderly patients premedicated with morphine sulphate 0.15 mg kg-1. The haemodynamic response to laryngoscopy and intubation was partially suppressed: neither arterial pressure nor heart rate exceeded awake values. During stable anaesthesia at the lower infusion rate before surgery, systolic (SAP) and diastolic (DAP) arterial pressures were significantly decreased from awake values (SAP: -47%; DAP: -46%) as a result of decreases in cardiac output (-32%) and systemic vascular resistance (SVR) (-9%). During surgery, with either spontaneous (SV) or intermittent positive pressure (IPPV) ventilation, both infusion rates were associated with decreases in arterial pressures when compared with the awake state. Cardiac output was decreased (SV: -35%, IPPV: -36%) and SVR increased (SV: +22%, IPPV: +45%) at the lower infusion rate; similar changes were observed during the faster infusion rate.

Hemodynamic effects of infusions of the emulsion formulation of propofol during nitrous oxide anesthesia in humans.

The hemodynamic response to anesthesia with the aqueous emulsion formulation of propofol was studied in healthy patients (ASA I or II), aged 39-57 yr, premedicated with morphine, 0.15 mg/kg. Anesthesia was induced in all patients with propofol, 2 mg/kg. Subsequently, patients were randomly assigned to two groups and maintained by a continuous intravenous infusion (group 1 received 54 micrograms X kg-1 X min-1, group 2 received 108 micrograms X kg-1 X min-1) to supplement 67% nitrous oxide. Three minutes after induction, systolic arterial pressure (SAP) decreased 28% (P less than 0.01) and was associated with decreased (-12%) cardiac output (Q70) and decreased (-15%) systemic vascular resistance (SVR). The hemodynamic response to tracheal intubation was not obtunded, but peak values of arterial pressures and heart rate did not exceed those recorded awake. Thirty minutes elapsed before repeating measurements prior to the first surgical incision. In group 1, SAP and Q70 decreased to 65% and 68% of awake values and in group 2 to 55% and 74% (P less than 0.05). Mild ventilatory depression persisted for the duration of spontaneous ventilation and was not reduced by the stimulus of surgery, which caused no significant hemodynamic responses in either group. Decreasing arterial PCO2 to the awake value by controlled ventilation increased SVR (P less than 0.05), but the associated increased SAP and decreased Q70 did not reach statistical significance. No patient reported awareness. The infusion of the emulsion formulation of propofol was associated with satisfactory anesthesia and recovery and with hemodynamic effects similar to those recorded with other intravenous anesthetics.

Dose requirements of propofol by infusion during nitrous oxide anaesthesia in man. I: Patients premedicated with morphine sulphate.

The study was performed to determine the ED50 and ED95 of a continuous infusion of the emulsion formulation of propofol during 67% nitrous oxide anaesthesia in 57 patients premedicated with morphine sulphate 0.15 mg kg-1. Anaesthesia was induced with propofol 2 mg kg-1, and maintained before incision with a fixed-rate infusion of propofol to supplement nitrous oxide. The response to the first surgical incision, made at least 30 min after induction of anaesthesia, was observed. The ED50 was 53.5 micrograms kg-1 min-1 and the ED95 was 112.2 micrograms kg-1 min-1. At the time of the first surgical incision, the venous whole blood concentrations of propofol at the ED50 and ED95 infusion rates (EC50 and EC95) were 1.66 micrograms ml-1 and 3.39 micrograms ml-1, respectively. The satisfactory maintenance of anaesthesia provided by nitrous oxide supplemented with propofol was associated with haemodynamic stability and rapid, uncomplicated recovery.

Propofol ('Diprivan') by intravenous infusion with nitrous oxide: dose requirements and haemodynamic effects.

The new formulation of propofol appears to be approximately equipotent to the previous formulation when used as an infusion to supplement nitrous oxide anaesthesia in patients premedicated with morphine. Preliminary haemodynamic studies indicate that the emulsion formulation causes more arterial hypotension than the original Cremophor formulation, though larger numbers are required to confirm this finding.

Use of "bollards" to improve patient access during intensive care.

Permanent floor-mounted "bollards" have been installed in three Intensive Care Areas in the Oxford Teaching Hospitals. Each brings services to one bed and, because access around the head is greatly improved in comparison with the conventional arrangement with the head next to the wall, facilitates both emergency and routine care and improves the safety of the working environment for staff and patients. Differences between the bollards installed in the three units are described and the advantages and disadvantages of each discussed. It is concluded that a bollard should be located to the left of the head of the bed and that it should be about 1100 mm high and 500 mm square. At least two oxygen and vacuum outlets, one air outlet, six electric power sockets and connections for monitoring cables should be provided on the bollard with further power sockets on the adjacent wall. A length of equipment rail mounted across the head of the bed supports the suction equipment required for oral and respiratory tract care and storage space is provided on and below the work surface which is mounted on the wall behind the head of the bed.

The influence of naloxone on regional hemodynamics in hemorrhaged rats.

Naloxone increases arterial pressure in hemorrhaged animals, but its effects on organ blood flows are not well established. We measured central and regional hemodynamics immediately before and 25 min or 55 min after hemorrhage in 33 anesthetized rats. Fifteen minutes after the beginning of hemorrhage, animals received either vehicle (n = 17) or naloxone (n = 16), 10 mg/kg, intravenously. At 25 min, animals treated with naloxone had a greater blood flow to the left cerebral hemisphere than those receiving vehicle, but all other measurements were similar. At 55 min, the mean arterial pressure and heart rate were greater in animals treated with naloxone, but blood flow was increased to the spleen only. Vascular resistance values were greater in the gastrointestinal tract and less in the spleen in animals receiving naloxone. The data confirmed that, in anesthetized rats, naloxone increased mean arterial pressure and splenic blood flow and transiently increased cerebral blood flow, but other regional flows and cardiac output were similar to those in rats receiving vehicle only.

Convulsions following regional hip blockade with bupivacaine and adrenaline.

Four out of 100 patients undergoing regional hip block (obturator nerve and nerve to obturator femoris) developed convulsions. These followed the injection of bupivacaine to block the nerve to the quadratus femoris muscle. The reasons for this are discussed. Not only has hip nerve regional blockade been shown to be ineffective in the relief of chronic pain of osteoarthritis but it must be concluded that the method described carries an unacceptably high morbidity.