Clinical Antecedents to In-Hospital Cardiopulmonary Arrest

A configuration register is incorporated into an electrically powered tourniquet apparatus for enabling an operator to change the values of parameters initially employed at the time of the next use of the apparatus, such as the initial pressure settings and elapsed time limits. These changed initial values of parameters are stored in memory and remain there despite inadvertent or intentional interruption of electrical power to the apparatus. An event register provides capability for recording the occurrence of events (cuff inflation, cuff deflation, etc.) and for relating the occurrence of the events to hazards and undesirable outcomes such as nerve damage associated with tourniquet usage. A safety circuit is included to detect and respond safely to certain failures which are possible within the tourniquet apparatus.

Physiologic tourniquet with safety circuit

The cardiovascular responses to the induction, maintenance, and recovery from anaesthesia with thiopentone, nitrous oxide and halothane, have been studied in seven elderly normotensive patients, seven untreated hypertensive patients, and fifteen patients under treatment with a variety of anti-hypertensive drugs. In five untreated and three treated hypertensive patients, all of whom had high arterial pressures before anaesthesia, severe reduction of arterial pressure occurred during anaesthesia and was associated with electrocardiographic evidence of myocardial ischaemia. Other treated hypertensive patients, whose arterial pressures were well controlled, behaved in a similar manner to the normotensive patients, and gave no ground for concern during anaesthesia. Cardiac output fell to the same extent (30 per cent) in all three groups, and where a great reduction of arterial pressure occurred it was largely due to reduction of initially high systemic vascular resistance. Baroreflex control of heart rate was significantly depressed in hypertensive patients both before and during anaesthesia. It is concluded that untreated high arterial pressure constitutes a serious risk to patients undergoing anaesthesia and surgery, and therefore anti-hypertensive therapy should not be withdrawn prior to anaesthesia without a compelling reason.

Studies of anaesthesia in relation to hypertension i: cardiovascular responses of treated and untreated patients

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The bacteriology of aspiration pneumonia

Seeking paresthesiae when performing a peripheral nerve block may increase the risk of post-anesthetic neurological sequelae. To test this hypothesis, we prospec-tively followed two groups of patients who underwent hand surgery with an axillary block. In one group, the axillary plexus was located by actively seeking paresthesiae; in the other, pulsations of the axillary artery indicated an adequate position of the injection needle. Mepivacaine 10 mg/ml, with or without adrenaline, was used. The study included 533 patients, 290 in the paresthesia group and 243 in the artery group.



Although unintentional, paresthesiae were elicited in 40% of patients in the artery group. Postanesthetic nerve lesions were seen in ten patients, eight in the paresthesia group and two in the artery group, all of whom had been blocked by mepivacaine with adrenaline. Symptoms varied between light paresthesiae lasting a few weeks, and severe paresthesiae, ache and paresis lasting more than 1 year. The etiology suspected was needle and perhaps injection trauma to the nerves during blocking. We conclude that whenever possible nerve blocks should be performed without searching for paresthesiae.

Paresthesiae or No Paresthesiae? Nerve Lesions after Axillary Blocks

SPIRATION of gastric contents into A the lungs during general anesthesia has been recognized as a serious problem since Simpson referred to this complication in 1848 as a possible cause of death.' The first report of death from aspiration during anesthesia appeared in 1853.2 At present 10 to 34 per cent of anesthetic deaths are believed to be caused by aspiration3 The morbidity rate is probably higher than suspected, particularly since several authors have shown that the aspiration can be unrecognized during an anesthetic proced ~ r e . ~ ' ( Many postoperative respiratory complications may result from this type of silent aspiration. Bannister and Sattilaros have presented an excellent review of the subject.

Aspiration pneumonitis: experimental studies and clinical observations.

Circulatory collapse following succinylcholine: report of a patient with diffuse lower motor neuron disease.

Hiccup: its possible cause and treatment in anesthesia.

Hyperkalemia followed the intravenous injection of succinylcholine (0.25 mg/kg) in dogs with bilaterally-sectioned sciatic nerves or transected spinal cords. The hyperkalemia was significant beginning after the fourteenth day, and became highly significant at 28 days (P

William Hamelberg

Papers

Aspiration pneumonitis: experimental studies and clinical observations.

Circulatory collapse following succinylcholine: report of a patient with diffuse lower motor neuron disease.

Hiccup: its possible cause and treatment in anesthesia.

Succinylcholine-induced Hyperkalemia in Dogs with Transected Sciatic Nerves or Spinal Cords

Intravenous regional anesthesia for surgery on the foot and ankle.