Acute circulatory support.

Numerous drugs can increase cardiac output, thereby improving tissue oxygen delivery, but often they do this at the expense of increasing myocardial oxygen demand. This may be critical when cardiac function is substantially impaired or ischaemia is the precipitating cause. Using polypharmacy to substantially improve cardiovascular status requires detailed knowledge of the pharmacodynamics and interactions of the available agents so that they may be tailored to the individual patient. In some settings combinations of inotropes and vasodilators may be desirable to minimise cardiac workload. In other instances vasopressors may be necessary to urgently restore a minimum perfusion pressure. This paper reviews the use of this group of drugs as well as the mechanical assist devices that may be used when drugs fail.

Delayed excitatory reaction following interaction of cocaine and monoamine oxidase inhibitor (phenelzine).

A case report is presented in which a patient receiving the monoamine oxidase inhibitor, phenelzine, developed a delayed excitatory reaction following administration of topical cocaine spray during anaesthesia for vocal cord surgery. The pharmacological basis of the drug interaction is discussed.

Depth of extradural space and dural puncture.

The records of 3011 obstetric extradural blocks were examined to determine the depth of the extradural space and the relative risk of dural puncture. The overall incidence of dural puncture was 0.7%. A disproportionate number of punctures occurred when the space was superficial (1.45%), with a risk factor three times greater than that associated with normal depth spaces (0.48%). Caution is advised when infiltrating with local anaesthetics before extradural procedures, and when initially introducing the extradural needle.

Anesthesia and mental illness.

Although drug interaction probably remains the most potentially serious problem, current evidence suggests that psychiatric medication need not be discontinued prior to anesthesia and surgery, discontinuation of medication may constitute its own hazards. Most interactions can be predicted and appropriate precautions taken, the use of meperidine is now absolutely contraindicated for patients receiving MAOI's.

Failure of extradural blockade in obstetrics. A new hypothesis.

Three-thousand and eleven consecutive obstetric extradural blocks were evaluated retrospectively. The distance from the skin to the extradural space was correlated with the incidence of unilateral blockade. There was a significant correlation (P less than 0.001) between an increasing distance and increased incidence of unilateral block. We propose that this is because of the topography of the extradural space, and because of the deviation of the tip of the needle from the midline (when using a midline approach).

Monoamine oxidase inhibitors and anaesthesia. A review.

There has been a recent renewal of interest in the use of monoamine oxidase inhibitors in psychiatry. The concurrent administration of anaesthetic agents, particularly narcotic analgesics, is often a cause for concern. Although many monoamine oxidase inhibitor-drug interactions have been reported, in practice it is only the interaction with pethidine which has led to fatalities. What is not appreciated is that the monoamine oxidase inhibitor-pethidine interaction has two distinct forms-"excitatory" and "depressive". It is this lack of appreciation that has led to much confusion when dealing with patients taking monoamine oxidase inhibitors.

The anion gap.

The majority of doctors can recognize and treat obvious biochemical disturbances on the basis of routine urea and electrolyte results. A useful (although nonspecific) guide to acid-base status is also contained among those figures: this is a derivative known as the anion gap. This article is a guide to the anion gap.

Disposable double-lumen tubes. A cost-effectiveness survey.

The use of red rubber double-lumen-bronchial tubes was studied in the Regional Cardiothoracic Centre and three large District General Hospitals to assess whether the use of disposable polyvinylchloride tubes was a viable cost-effective alternative. In the Regional Cardiothoracic Centre red rubber tubes were used frequently throughout their predicted lifespan and were cost effective. In the district hospitals red rubber tubes were unlikely to be used sufficiently to justify their cost. Many district general hospitals could reduce capital expenditure and annual costs by changing from red rubber to disposable polyvinyl chloride double lumen tubes.

Caesarean section under extradural analgesia in a patient with Ebstein's anomaly.

Ebstein's anomaly is a rare congenital malformation of the tricuspid valve, often associated with an atrial septal defect. Death occurs usually from cardiac arrhythmias. The successful use of a two-catheter technique for elective Caesarean section with extradural analgesia is described and the hazards associated with Ebstein's anomaly in pregnancy and anaesthesia are discussed.