High-energy versus low-energy defibrillation: experience in patients (excluding those in the intensive care unit) at Mayo Clinic-affiliated hospitals.

/he purpose of this study was to determine whether electric shocks of low (200 to 240 J), intermediate (300 to 320 J), or high (400 to 440 J) delivered energy were most successful in defibrillating hospitalized patients (excluding those in intensive care units) in whom resuscitation was attempted by a code emergency team. From January 1980 through December 1982, 101 cases of ventricular fibrillation in 100 patients were treated by Mayo Clinic code emergency teams. Many of the patients in this trial had secondary or agonal ventricular Defibrillation. Most patients (64%) were defibrillated by one to eight shocks. For the first shock, intermediate and high energy seemed to be more effective than low energy. Patient weight, time of delivery of shock 1 after onset of the code emergency, blood pH, acute and chronic medical diagnoses, and pharmacotherapy before the onset of ventricular fibrillation were not clearly related to the response to shock 1. Nine of 16 patients who did not initially respond to shocks of low or intermediate energy were defibrillated when higher energy was subsequently used. Only 14 patients ultimately survived and were dismissed from the hospital. These results suggest that in this patient population, high levels of delivered energy are preferable to low energy for the first shocks administered; we recommend that 400 J of delivered energy be used initially. The 360-J maximal energy dose available in most currently manufactured defibrillators should be sufficiently close to this recommendation to justify use of that dose with the initial shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of the glucose intolerance of thiazide diuretics by maintenance of body potassium.

The effect of thiazide diuretics on the glucose tolerance of seven normal men in whom potassium loss was prevented with supplementation was studied using the glucose clamp technique. An initial control 2-h hyperglycemic clamp was performed to create a square wave of hyperglycemia 125 mg/dl above basal. At 1 h, 40 g glucose/m2 body surface area was ingested. Serial insulin (IRI) and gastric inhibitory polypeptide (GIP) levels were measured as well as the level of glucose infusion necessary to maintain the stable hyperglycemic level. After the initial study, subjects were placed on a 10-day course of 100 mg hydrochlorothiazide and 80 meq potassium per day. Subjects were monitored for dietary potassium intake, urinary potassium, and sodium losses, and the replacement of potassium adjusted accordingly. A repeat glucose clamp was done on day 10. When potassium losses were prevented, thiazides induced no alterations in glucose tolerance, beta-cell sensitivity to glucose, GIP-cell sensitivity to glucose, beta-cell sensitivity to GIP, or tissue sensitivity to insulin. Two control studies in which hypokalemia was allowed to ensue after hydrochlorothiazide ingestion revealed a diminution in glucose tolerance, a consequence of diminished pancreatic beta-cell response to glucose. We conclude that the thiazide effect on glucose tolerance is a consequence of the resultant hypokalemia that the diuretic may create.

Interaction of arginine and gastric inhibitory polypeptide on insulin release in man.

The interrelations of the insulin secretagogues, glucose, arginine (Arg), and gastric inhibitory polypeptide (GIP) were quantified in six normal young men in five sets of experiments with the hyperglycemic clamp technique (125 mg/dl above basal glucose levels for 2 h). After 60 min of intravenous glucose alone, one of the following was added: A) oral glucose (OG) (40 g/m2); B) 15 g.m-2.h-1 Arg infusion; C) 15 g.m-2.h-2 Arg infusion and OG; D) 7.5 g.m-2.h-1 Arg; E) 7.5 g.m-2.h-1 Arg and OG. The clearance rate of Arg was similar for B, C, D, and E. In all experiments, plasma GIP levels were unchanged from the basal level during the 1st h. The increases in plasma GIP levels in experiments C and E were similar to the increase when OG alone was ingested (A). When the stimulatory effect of the secretagogue(s) alone on insulin (IRI) is computed, the increase due to OG (A) and to 7.5 g.m-2.h-1 Arg (D) were similar and additive (A + D approximately equal to E). However, the stimulatory effect of 15 g.m-2.h-1 Arg + OG (C) on IRI was not significantly greater than 15 g.m-2.h-1 alone (B). The 15 and 7.5 g.m-2.h-1 Arg infusion produced different patterns of insulin and glucagon secretions. At the lower dose, the response of both hormones to Arg decreased with time. Arg and GIP act through a similar and possibly common mechanism on the beta-cell. However, only Arg was found to be alpha-cytotropic. GIP does not appear to influence the metabolic clearance of Arg. The dose-response relationships to Arg of the beta- and alpha-cell appear similar.

Longitudinal changes in serum cholesterol in man: an epidemiologic search for an etiology.

Serum cholesterol levels were determined in 1011 male participants of the Baltimore Longitudinal Study of Aging. This study presents the longitudinal changes in serum cholesterol from 1 July 1963 to 30 June 1977. Serum cholesterol values dropped 6% between 1970 and 1972. The span of this study was divided into two eras, one preceding and one following the drop. The effects of obesity, selected dietary constituents and physical activity were examined in an attempt to explain the secular change in serum cholesterol. Serum cholesterol levels were not significantly correlated to levels of weight or body mass index. Changes in weight were significantly positively correlated with changes in serum cholesterol. Overall, however, the study population did not experience a significant drop in weight and therefore, this relationship could not explain the observed drop in serum cholesterol. There were virtually no significant correlations between the absolute value of any of the dietary variables examined and the absolute level of serum cholesterol. There were significant but small changes in most dietary constituents; however, only changes in caloric intake were significantly positively correlated with changes in serum cholesterol. Because the overall change in caloric intake was small, it could explain less than 1 mg/dl of the 11 mg/dl drop. There was no overall change in physical activity. No significant correlations were found between either the level or change in physical activity and the level or change in serum cholesterol. It is concluded that neither weight nor physical activity could account for the observed changes in serum cholesterol. Changes in dietary constituents were significant and in a direction which would predict a lower serum cholesterol. However, for the group, dietary changes could not fully explain the drop in serum cholesterol. For individuals, the changes in diet poorly predicted changes in serum cholesterol. It is suggested that the observed secular drop in serum cholesterol may be due to factor(s) other than those studied.

Ventricular tachycardia secondary to aneurysm of sinus of Valsalva.

A patient with unruptured aneurysm of the sinus of Valsalva presented because of ventricular tachycardia refractory to medical therapy. The underlying problem was not suspected until cardiac catheterization. Once the aneurysm was repaired, the tachycardia was abolished; the patient required no antiarrhythmic drugs. Two points are emphasized: First, cardiac catheterization is often indicated early in cases of ventricular tachycardia without obvious cause. Second, recurrent ventricular tachycardia is a hitherto unreported but important complication of sinus of Valsalva aneurysm.