William J. Grace

Inappropriate ventilation and hypoxemia as causes of cardiac arrhythmias: The control of arrhythmias without antiarrhythmic drugs

Abstract Severe ventricular and supraventricular arrhythmias may be produced by inappropriate ventilation (hyperventilation or hypoventilation), hypoxemia or metabolic acidosis. Conventional therapy with antiarrhythmic drugs and precordial counter-shock is ineffective unless the underlying metabolic abnormalities are corrected. Nine representative patients are described and the physiologic determinants of hypoxemia and hyperventilation in the critically ill patient discussed.

Hemodynamics, coronary blood flow, and myocardial metabolism in coronary shock; response to l-norepinephrine and isoproterenol

Hemodynamics and myocardial metabolism were evaluated in 18 patients in cardiogenic shock following acute myocardial infarction. The response to l-norepinephrine was studied in seven cases and the response to isoproterenol in four cases. Cardiac index (CI) was markedly reduced, averaging 1.35 liters/min per m(2). Mean arterial pressure ranged from 40 to 65 mm Hg while systemic vascular resistance varied widely, averaging 1575 dyne-sec-cm(-5). Coronary blood flow (CBF) was decreased in all but three patients (range 60-95, mean 71 ml/100 g per min). Myocardial oxygen consumption (MV(O2)) was normal or increased ranging from 5.96 to 11.37 ml/100 g per min. Myocardial oxygen extraction was above 70% and coronary sinus oxygen tension was below 22 mm Hg in most of the patients. The detection of the abnormal oxygen pattern in spite of sampling of mixed coronary venous blood indicates the severity of myocardial hypoxia. In 15 studies myocardial lactate production was demonstrated; in the remaining three lactate extraction was below 10%. Excess lactate was present in 12 patients. During l-norepinephrine infusion CI increased insignificantly. Increased arterial pressure was associated in all patients by increases in CBF, averaging 28% (P < 0.01). Myocardial metabolism improved. Increases in MV(O2) mainly paralled increases in CBF. Myocardial lactate production shifted to extraction in three patients and extraction improved in three. During isoproterenol infusion CI increased uniformly, averaging 61%. Mean arterial pressure remained unchanged but diastolic arterial pressure fell. CBF increased in three patients, secondary to decrease in CVR. Myocardial lactate metabolism deteriorated uniformly; lactate production increased or extraction shifted to production. In the acute state of coronary shock the primary therapeutic concern should be directed towards the myocardium and not towards peripheral circulation. Since forward and collateral flow through the severely diseased coronary bed depends mainly on perfusion pressure, l-norepinephrine appears to be superior to isoproterenol; phase-shift balloon pumping may be considered early when pharmacologic therapy is unsuccessful.

Accidental hypothermia in an alcoholic population

Abstract Thirty-nine cases of accidental hypothermia are reviewed. Data indicate that mortality varies with the presence of underlying disease rather than with the degree of hypothermia or the methods of rewarming. In 31 patients with hypothermia alone (average temperature 85 °F) mortality was 6.25 per cent. In eight patients with hypothermia and another primary condition (average temperature 84 °F) mortality was 75 per cent. Intractable cardiac arrhythmia has been reported as the primary cause of death in hypothermia. In these patients, death during hypothermia resulted from pulmonary complications. Ventricular arrhythmias, when they occurred, were responsive to routine measures such as electrical cardioversion and myocardial suppressant drugs. Methods of treatment are discussed.

Extreme hypocapnia in the critically III patient

Abstract Respiratory alkalosis was the most common acid-base disturbance observed in a computer analysis of 8,607 consecutive arterial blood gas studies collected over an 18 month period in a large intensive care unit. Through a retrospective review of the randomly selected hospital records of 114 patients, we defined four groups based upon arterial carbon dioxide tension (PaCO 2 ) and mode of ventilation. Group 1, with a PaCO 2 of 15 mm Hg or less, consisted of 25 patients with an over-all mortality of 88 per cent. Group II, with a PaCO 2 of 20 to 25 mm Hg, consisted of 35 patients with a mortality of 77 per cent. Group III, with a PaCO 2 of 25 to 30 mm Hg, consisted of 33 patients with a mortality of 73 per cent, and Group IV, with a PaCO 2 of 35 to 45 mm Hg, consisted of 21 patients with a mortality of 29 per cent (p These findings suggest that extreme hypocapnia in the critically ill patient has serious prognostic implications and is indicative of the severity of the underlying disease.

Subacute Pulmonary Infiltration Due to Nitrofurantoin

Excerpt Pulmonary infiltrations as manifestations of allergy to nitrofurantoin, with or without pleural effusion, have been reported. Israel and Diamond (1) were able to prove the etiology of the p...

Mobile Coronary Care Unit.

Excerpt The mobile coronary care unit consists of a team of physicians and nurses. This team carries, via ambulance, battery-operated portable instruments. With these the team sets up a coronary ca...

Principle defects which account for shock following acute myocardial infarction in man: implications for treatment.

Shock following acute myocardial infarction is closely related to the volume of damaged myocardium. For this reason, the main therapeutic effort should be directed towards improvement of myocardial oxygenation rather than improvement of cardiac performance. Hemodynamics and cardiac energetics were studied in 25 patients in myocardial infarction shock. Hemodynamic abnormalities associated with shock were emphasized when compared to data from 40 patients with acute myocardial infarction but not in shock.Isoproterenol increased cardiac index an average of 0.87 1/min/M2 and heart rate by 20 beats/min; coronary blood flow rose an average of 12 ml/100g/min in face of decreased diastolic aortic (coronary perfusion) pressure; rate of myocardial lactate production increased. L-norepinephrine increased mean aortic pressure and coronary blood flow an average of 21 mm Hg and 27 ml/100g/min; mean myocardial oxygen consumption rose 2.24 ml/100g/min; myocardial lactate production shifted to extraction (mean, 12%); myocardial oxygen extraction remained abnormally high (mean, 73%); cardiac index did not change. Intra-aortic counterpulsation in-creased mean aortic pressure and coronary blood flow an average of 14 mm Hg and 23 ml/100g/ min; myocardial oxygen consumption remained essentially unchanged; both myocardial lactate and oxygen extraction improved toward normal values (15% and 61%); cardiac index in-creased an average of 0.48 1/min/M2.Isoproterenol appears to be harmful in myocardial infarction shock in that it increased myocardial oxygen demand more than oxygen supply. L-norepinephrine seems to be the vasoactive agent of choice in the initial treatment of shock because it improved myocardial perfusion and metabolism but not cardiac index. Intra-aortic counterpulsation improved both coronary and peripheral circulation and the myocardial metabolism changed towards normal. Mortality remained unchanged during the three different therapeutic interventions; emphasizing the importance of early recognition of the pre-shock state and of further aggressive diagnositc and therapeutic measures.

Resuscitation of the severely ill patient with acute myocardial infarction

Abstract Three certain cases and 1 questionable case of acute myocardial infarction complicated by acute pulmonary edema and cardiac arrest are presented. All patients survived. The implications of resuscitation in these severely ill patients with acute myocardial infarction are discussed.

The Intermediate Coronary Care Unit.

Excerpt After discharge from a coronary care unit a number of patients die. As much as 30% of all hospital deaths from acute myocardial infarction occur after the sixth day or after discharge from ...

Probenecid (Benemid) intoxication with status epilepticus

Abstract A forty-nine year old man who attempted suicide by taking 47 gm. of probenecid and who recovered subsequently is described. There has been no previous documentation of probenecid overdosage in man, although various toxic effects with average doses have occasionally been reported. The clinical manifestations included coma and status epilepticus. The serum urate fell to very low levels. No significant alterations in the metabolism of calcium or phosphorus could be demonstrated.