ERYTHERMALGIA. REVIEW OF 51 CASES

The syndrome of erythermalgia is characterized by a burning distress of the extremities that is accompanied by redness and increased temperature of the skin. These symptoms are initiated or exacerbated by an increase in environmental temperature and diminished by measures that cool the skin. Of 51 patients with this clinical syndrome seen at the Mayo Clinic during the years 1951 to 1960 inclusive, 30 were considered as having primary erythermalgia because of the absence of demonstrable associated conditions, and the rest were classified as having secondary erythermalgia because the condition was associated with various diseases. Particularly significant was the relation of erythermalgia to the myeloproliferative disorders as evidenced in 10 cases. In some of these cases, erythermalgia preceded other manifestations of the myeloproliferative disorder by as long as 12 years. The primary type was found to occur in younger individuals and to be more often bilateral, to produce pain of greater intensity, and to involve larger areas of the affected extremities. The pathologic physiology of this syndrome remains unknown.

CHANGES IN SERUM AND URINARY POTASSIUM LEVELS DURING PROFOUND HYPOTHERMIA IN MAN

Samples of blood were taken at five to 10-minute intervals during cooling, circulatory arrest, and rewarming in eight consecutive patients undergoing open cardiac surgery under profound hypothermia at nasopharyngeal and oesophageal temperatures of approximately 10 degrees C. and the serum potassium levels were estimated. Urine samples were also collected from six of the eight patients and the total potassium excretion calculated per minute. It was found that there was a tendency for the serum potassium level to rise towards the end of cooling. A further more significant rise occurred during circulatory arrest, and on rewarming there was a pronounced fall of approximately 2.5 mEq./litre, the lowest level being reached at 27.5 degrees C. Above 27.5 degrees C. there was no further significant change in the serum potassium level. It is suggested that the acidosis which occurs during circulatory arrest and a depression in the function of the cell membrane at very low temperatures are at least partly responsible for the changes in serum potassium. Certainly the excretion of potassium in the urine does not account for them.

EFFECT OF TEMPERATURE ON ARTERIAL BLOOD GAS TENSIONS AND PH DURING EXERCISE

We measured arterial blood Po2, Pco2 and pH at rest and during a standard exercise test on a bicycle ergometer in ten normal subjects. In five we measured esophageal and five arterial blood temperature during the exercise and corrected the arterial blood values to the temperature at the time the samples were collected. We found an average rise in temperature of 1 C (range 0.2–1.6 C) during exercise lasting about 30 min at loads up to an average of 1,200 kg-m/min. At the highest load the average correction for PaOO2 was 5.6 mm Hg, for PaCOCO2 1.6 mm Hg and for pH 0.014 units. Our corrected values showed a fall in PaCOCO2 and pH and a rise in PaOO2 during severe exercise. These findings are compatible with the development of a metabolic acidosis during severe exercise and indicate that our subjects were not limited by diffusion across the alveolar-capillary membrane.

metabolic acidosis; alveolar capillary membrane diffusion; hyperventilation; PaOO2 and PaCOCO2 in severe exercise

Submitted on June 17, 1963

SOME PHARMACOLOGICAL EFFECTS OF A SERIES OF TRYPTAMINE DERIVATIVES

The methods of synthesis and some pharmacological properties of a number of N-substituted tryptamines are described. Peripheral vasopressor activity decreased with increase in complexity of the substituent and was not related to toxicity or to behavioural activity. Activity in increasing the rectal temperature of rabbits appeared to parallel modifications in the open-field behaviour of rats. Some compounds were investigated for their ability to block a conditioned avoidance-response in rats and to affect operant conditioning in cats. Evidence is presented which suggests that the tryptamine derivatives are metabolized in vivo to more active forms.