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Biomedical subjects

W Buzello

Publications and source records attributed to W Buzello.

At least 55 records · Page 3Linked to original sources
PubMed1986

A constant current peripheral nerve stimulator (Neurostim T4). Description, and evaluation in volunteers.

A pocket-size, battery-powered peripheral nerve stimulator featuring a calibrated constant current floating output (max. 80 mA) was evaluated in unanaesthetized volunteers. Modes of stimulation included continuous 1 Hz, continuous train-of-four every 15 s, and on-demand tetanus (50 Hz per 5 s). Within the limits of 0-250 V, voltage adjusted automatically for 0.2-ms monophasic square pulses. Between 20 and 80 mA, the dial error of current intensity was less than +/- 5%. Maximum allowable resistance for the generation of 40-mA pulses was 5 k omega--that is five times the average tissue impedance as measured in 15 volunteers. With surface electrodes, the current intensity required for maximal indirect muscle stimulation in another 50 individuals was 38 +/- 23 mA (mean +/- SD). With up to 80 mA stimulus current, supramaximal nerve stimulation was obtained in 94% of the volunteers.

Adult↗
PubMed1985

Plasma levels of norepinephrine and epinephrine during malignant hyperthermia in susceptible pigs.

Malignant hyperthermia (MH) is a genetic disease of man, swine, dogs, cats, and horses. The syndrome is normally triggered by inhalational anesthetics or the administration of depolarizing muscle relaxants such as succinylcholine or various environmental stress factors. We have used the MH-susceptible pig as an animal model to study the hormonal changes developing during this highly lethal syndrome. High-performance liquid chromatography with electrochemical detection was used for the quantitation of the plasma levels of norepinephrine and epinephrine during MH. This research presents evidence that the rapid release of massive quantities of norepinephrine (up to 108 ng/ml) into the blood stream occurs simultaneously with the initiation of tachycardia which is the herald signal of the onset of MH. Norepinephrine levels exceed epinephrine by a 4:1 ratio early in the syndrome. Even pigs with MH which do not develop the muscle rigor phase have high levels of circulating norepinephrine. Tachycardia, pulmonary hypertension, increased venous oxygen desaturation, and increasing core temperature develop as the syndrome progresses.

Animals↗
PubMed1985

Vecuronium and porcine malignant hyperthermia.

Vecuronium was studied in eight malignant hyperthermia (MH) susceptible pigs for its potential to either trigger or prevent MH. Two sets of experiments were performed in the same animals: 1-hr total neuromuscular blockade by vecuronium infusion with thiopental anesthesia in the absence of invasive monitoring and halothane; and 1-hr infusion of vecuronium with thiopental anesthesia with invasive monitoring in the absence of and then, followed by 30-min infusion in the presence of halothane, followed in turn by exposure to halothane alone. One-hour infusion of vecuronium in the absence of halothane and invasive monitoring did not trigger MH in any animal. During the second set of experiments, MH, evidenced by rising rectal temperature, elevated end-tidal PCO2, mixed venous oxygen desaturation and muscle rigor, occurred in one animal during vecuronium alone, in four animals during vecuronium infusion and simultaneous exposure to halothane, and in three animals during exposure to halothane alone after recovery from vecuronium neuromuscular blockade. In view of the results of control experiments, the development of MH during vecuronium neuromuscular blockade before exposure to halothane was attributed to surgical stress rather than to vecuronium itself. It is concluded that vecuronium is not a trigger to MH in susceptible pigs.

Anesthesia, General↗
PubMed1984

Comparison between the continuous infusion of vecuronium and the intermittent administration of pancuronium and vecuronium.

The neuromuscular blocking effects of repeated bolus injections of pancuronium, or vecuronium, and of the continuous infusion of vecuronium have been compared in 36 patients by means of evoked twitch tension. Groups I and II received a loading dose (0.075 mg kg-1) of pancuronium or vecuronium, respectively, followed by 0.015-mg kg-1 maintenance doses when twitch tension had recovered to 25% of control. Group III received a 0.075-mg kg-1 loading dose of vecuronium plus a continuous infusion (commenced simultaneously) delivering 0.075 mg kg-1 h-1. With repeated injections of pancuronium (group I) or vecuronium (group II), the durations of blockade to 25% recovery were 64 and 25 min, respectively. Maintenance doses had to be injected every 42 min with pancuronium and every 12 min with vecuronium. The recovery times from 25% to 75% of control twitch tension were 44 v. 12 min. The continuous infusion of vecuronium (group III) produced consistent neuromuscular blockade at an average level of 87% twitch depression. The times from the end of infusion to 25%, and from 25% to 75%, recovery averaged 20 and 26 min, respectively. These values did not correlate with the total dose of vecuronium infused. For clinical practice, the suggested loading dose is 1.5 times the ED90 (= 0.07 mg kg-1) followed by an infusion of the same dose per hour. The infusion should be started within 10 min of the injection of the loading dose.

Adult↗
PubMed1982

Hazards of neostigmine in patients with neuromuscular disorders. Report of two cases.

In a 57-yr-old female with dystrophia myotonica, attempts to reverse residual non-depolarizing block with neostigmine 1.0 mg were only partially effective and the administration of the further dose (0.5 mg) produced long-lasting muscle weakness. The train-of-four response of this patient resembled that of the depolarizing block and suggested an alteration in the electrical properties of the muscle membrane. A 50-yr-old male with a 30-yr history of progressive muscle dystrophy, exhibited a tonic response to neostigmine in the evoked mechanomyogram during recovery from partial neuromuscular block. It is concluded that the type of reaction to neostigmine in patients with neuromuscular disease in unpredictable.

Anesthesia, General↗
PubMed1982

[Neostigmine and dehiscence of intestinal anastomoses (author's transl)].

In a study from 1968, anastomotic leakage was reported to be nine times as frequent if neostigmine was used for reversal of curare action than in control patients. Subsequent studies did not confirm this finding although it is not disputed that neostigmine activates bowel peristalsis. Both animal experiments and clinical observations indicate that anastomoses in undamaged bowel, if properly done, withstand all kinds of hyperperistalsis. However, it cannot entirely be excluded that coincident pathologic conditions (cachexia, damaged bowel, chronic steroid medication, anaemia etc.) may occur, in which neostigmine administration is unsafe. Appropriate anaesthesiological techniques to avoid the need for neostigmine include titration of the individual relaxant requirement by means of a peripheral nerve stimulator, preference of intermediate or short-acting nondepolarizing muscle relaxants and primary postoperative mechanical ventilation. If nevertheless reversal of residual nondepolarizing block is decided, it should be performed with deep halothane anaesthesia still maintained and by means of an anticholinesterase agent with little muscarinic side effect such as edrophonium (0.5-1.0 mg/kg).

Anesthesia, General↗
PubMed1980

[Pulmonary embolectomy using extracorporeal circulation. An anesthesiological and intensive care viewpoint (author's transl)].

Three cases of massive pulmonary embolism are described in order to illustrate the indications for open pulmonary embolectomy with temporary cardiopulmonary bypass. Surgical treatment is mandatory in the presence of shock with systemic arterial hypotension below 90 mm Hg, arterial hypoxaemia more than 50 per cent as demonstrated by pulmonary arteriography, and pulmonary mean pressure exceeding 30 mm Hg. Additionally the prognosis of the underlying disease should be considered. The specific problems related to anesthesia are associated with the severe shock and its concomitant excessive acid base disturbances both of them being refractory to medical treatment.

Acid-Base Imbalance↗