PubMed Health⌕ Search

Biomedical subjects

W K Thompson

Publications and source records attributed to W K Thompson.

8 recordsLinked to original sources
PubMed1994

Succinylcholine-induced cardiac arrest in children with undiagnosed myopathy.

Two paediatric cases are reported in which unexpected, life-threatening arrhythmias occurred. Routine induction of general anaesthesia with thiopentone, 5 mg.kg-1, in one and with halothane in the other, and succinylcholine 1.25-1.5 mg.kg-1 i.v. was followed by the development of wide complex tachyarrhythmia with hypotension in the first case and asystole in the second case despite pre-treatment with atropine in both cases. The first patient was resuscitated with tracheal intubation, 100% oxygen, manual ventilation and intravenous lidocaine and bicarbonate. The second patient required intubation, manual ventilation, 12 min of CPR and i.v. calcium, epinephrine and bicarbonate, as well as DC counter shock. Neither patient received dantrolene. Early recovery in both patients was uneventful with no neurological sequelae. Subsequent investigations revealed the presence of a dystrophin-deficient muscular dystrophy, Duchenne muscular dystrophy and Becker muscular dystrophy respectively, previously unsuspected, in both patients. The aetiology of the observed arrhythmias was presumably hyperkalaemia, secondary to succinylcholine-induced rhabdomyolysis. It is suggested that when faced with sudden, life-threatening arrhythmias following succinylcholine at induction of anaesthesia for paediatric patients, clinicians should include occult myopathy in the differential diagnosis, and thus consider the aggressive management of hyperkalaemia in addition to basic resuscitative efforts.

Anesthesia, Intravenous↗
PubMed1994

Comparing the subjective, psychomotor and physiological effects of intravenous butorphanol and morphine in healthy volunteers.

The purposes of this study were to characterize the subjective, psychomotor and physiological effects of butorphanol in healthy nondrug-abusing volunteers and to compare and contrast the effects of butorphanol to those of morphine. Into an antecubital vein, the subjects (seven men and five women), who had no history of opiate dependence, were injected with 0, 0.5, 1.0 or 2.0 mg/70 kg of butorphanol or 10 mg/70 kg of morphine; a randomized, double-blind, crossover design was used. The subjective effects of butorphanol included increased scores on the Pentobarbital-Chlorpromazine-Alcohol Group scale and Lysergic Acid Diethylamide scale of the Addiction Research Center inventory; increased visual analog scale ratings of "sedated," "coasting or spaced out" and "difficulty concentrating;" increased adjective checklist ratings of "sweating," "skin itchy" and "sleepy;" and increased "feel drug effect" and drug-liking ratings. Morphine had some subjective effects of a magnitude similar to those of an equianalgesic dose of butorphanol (2 mg) (e.g., "strength of drug effect," "sedated," "heavy or sluggish feeling" and "high"). However, other effects of morphine were lesser in magnitude (e.g., "coasting or spaced out," "drunken" and "lightheaded") than those of butorphanol. Also, morphine did not affect a number of ratings that were affected by butorphanol (e.g., "confused," "dreamy," "stimulated," "difficulty concentrating," "floating" or "sweating"). The psychomotor impairing effects of butorphanol, as measured by the Maddox Wing test, an eye-hand coordination test, and the Digit Symbol Substitution Test, were dose related; in contrast, morphine had no effect on psychomotor functioning. Both butorphanol and morphine induced miosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A dose-response analysis of the subjective, psychomotor and physiological effects of intravenous morphine in healthy volunteers.

The purpose of this study was to characterize the subjective, psychomotor and physiological effects of morphine in healthy volunteers. Subjects (10 males and 2 females) without histories of opiate dependence were injected in an antecubetal vein with 0, 2.5, 5.0 or 10 mg/70 kg of morphine, by using a randomized, double-blind, cross-over design. Subjective effects, psychomotor performance and physiological measures were assessed immediately before the injection and for up to 5 hr afterward. Morphine increased the Pentobarbital-Chlorpromazine-Alcohol Group, Amphetamine, the Lysergic Acid Diethylamide and the Morphine-Benzedrine Group scores and decreased Benzedrine Group scores on the Addiction Research Center Inventory. Increased visual analog scale ratings of "stimulated," "high," "sedated," "coasting or spaced out" and "drunken" were also obtained. On an opiate adjective checklist, subjects reported increased ratings of "flushing," "dry mouth" and "tingling." Drug liking was not significantly altered by morphine, but there was substantial intersubject variability with this measure. Some aspects of psychomotor performance (reaction time, Digit Symbol Substitution Test and Maddox Wing) were impaired by morphine; however, eye-hand coordination was not. Miosis was induced by morphine. Most effects of morphine were dose-related, some effects peaked soon after morphine injection (e.g., increased stimulated and high ratings) and dissipated gradually, whereas other effects did not peak until later into the session (sedation or exophoria). Our results are fairly consistent with other studies examining morphine effects in healthy volunteers, and also indicate that the profile of morphine effects differ between healthy volunteers and those with a history of opiate dependence.

Adult↗
PubMed1982

High-frequency oscillation compared with standard ventilation in pulmonary injury model.

Hemorrhagic pulmonary edema was induced by intra-atrial infusion of 0.04--0.1 ml/kg of oleic acid into six anesthetized dogs. Gas exchange and cardiac outputs were then compared at identical mean airway pressures during randomized ventilation with either a volume-cycled ventilator with positive end-expiratory pressure (conventional positive-pressure ventilation, tidal volume 16--21 ml/kg, frequency 15--20 cycles/min) or a variable volume piston pump operating at 15 Hz (high-frequency oscillation). The fractional inspired oxygen concentration was maintained at 0.5 throughout. During 17 data sets matched for intratracheal mean airway pressures over a range of 7.5--27 cmH2O, measurements of systemic arterial pressure, arterial blood gas tensions, thermodilution cardiac outputs, and pulmonary arterial and capillary wedge pressures were identical (P less than 0.05) during ventilation with conventional positive-pressure ventilation and high-frequency oscillation. With both forms of ventilation, arterial oxygen tension progressively improved as mean airway pressure increased. In a shunt model of acute lung injury we were unable to show significant differences in oxygenation or cardiac output when high-frequency oscillation was compared with conventional positive-pressure ventilation with positive end-expiratory pressure at equivalent mean airway pressures.

Animals↗
PubMed1981

Treatment of RDS by high-frequency oscillatory ventilation: a preliminary report.

The feasibility of high-frequency oscillatory ventilation was investigated in eight neonates with severe RDS. Low-volume, high-frequency flow oscillations were generated by a piston pump and delivered through standard endotracheal tubes. Oscillatory frequencies ranged from 8 to 20 Hz and mean airway pressure from 9 to 20 cm H2O. Heart rate, airway pressures, and arterial blood gases and blood pressure were monitored during both continuous positive pressure ventilation and HFO. During HFO mean PaCO2 was 44.0 +/- 4.8 mm Hg. During CPPV immediately prior to oscillation an FIO2 of 0.66 +/- 0.15 resulted in a PaO2 of 59.6 +/- 17.0 mm Hg. Oxygenation improved during HFO such that a mean FIO2 of only 0.41 +/- 0.11 was needed for similar oxygenation. Improvements in oxygenation correlated directly with increases in mean airway pressure. Based on an animal model the phasic pressure swings during HFO are estimated to be 5 to 7 cm H2O in the trachea, much less than conventional ventilation. We conclude that HFO shows great promise in the support of gas exchange in infants with RDS. The use of small phasic volume and pressure swings should minimize pulmonary barotrauma. HFO should also permit the use of lower inspired oxygen fractions.

Humans↗
PubMed1981

Vagotomy reverses apnea induced by high-frequency oscillatory ventilation.

Apnea has been observed in both animals and patients during high-frequency oscillatory ventilation. The effects of vagotomy were studied during periods of oscillator-induced apnea in 11 pentobarbital-anesthetized dogs. The animals were intubated and breathing spontaneously. An arterial cannula was inserted for monitoring blood pressure and blood gases. Intratracheal airway pressure was measured, and respiratory activity was assessed using either an intrapleural catheter or esophageal balloon. The dogs then underwent high-frequency ventilation at 15 Hz. Apnea was induced by appropriate selection of volume displacement of the piston pump and the distal airway pressure in eucapnic animals. Segments of right and left vagus nerves were exposed in the neck, bathed in local anesthetic, and transected. Spontaneous ventilation resumed immediately in nine animals and could not be suppressed at the same CO2 partial pressure despite continuation of oscillation. We conclude that the apnea observed during high-frequency ventilation is mediated by active vagal inhibition of central respiratory activity and is usually reversed by vagotomy.

Animals↗
PubMed1980

Ventilation by high-frequency oscillation.

The effect of applying a high-frequency small-volume sinusoidal oscillation at the airway was investigated in anesthetized apneic beagle dogs (mean wt 11 kg, mean VDphys 6.6 +/- 0.6 ml/kg). Oscillations generated by a piston in a cylinder were transmitter to the lungs through an uncuffed endotracheal tube (4.5 mm ID, 6.0 mm OD), which allowed a substantial leak back through the vocal cords. A bias flow of fresh gas presented inspired air to the midtracheal level. The minimum distal airway pressure (measured at the end of the endotracheal tube) was maintained between 0 and 2 cmH2O. Peak airway pressures were 4-8 cmH2O. The optimal frequency for CO2 elimination was 15 Hz. Using volumes of 1.9 ml/kg (range 1.7-2.3) at this frequency the mean PaCO2 was 33.1 +/- 0.5 Torr. In four dogs breathing 100% O2 the PaO2 was 594 +/- 9 Torr during spontaneous ventilation and 580 +/- 9 Torr after 5 h of uninterrupted oscillation. In four experiments using room air the PaO2 was 95 +/- 5 Torr during spontaneous respiration and 106 +/- 1 Torr after 5 h of oscillation. In an additional seven studies there was no difference in mean cardiac output between oscillation and conventional mechanical ventilation. This study demonstrates that high-frequency small-volume oscillations can maintain gas exchange for many hours presumably by markedly enhancing the diffusivity of gases in the lung.

Animals↗