Simon Bursztein

Comparison of sodium bicarbonate, Carbicarb, and THAM during cardiopulmonary resuscitation in dogs

OBJECTIVES During cardiopulmonary resuscitation (CPR), elimination of CO2 was shown to be limited by low tissue perfusion, especially when very low perfusion pressures were generated. It has therefore been suggested that sodium bicarbonate (NaHCO3), by producing CO2, might aggravate the hypercarbic component of the existing acidosis and thereby worsen CPR outcome. The objectives of this study were to evaluate the effects of CO2 producing and non-CO2 producing buffers in a canine model of prolonged ventricular fibrillation followed by effective CPR. DESIGN Prospective, randomized, controlled, blinded trial. SETTING Experimental animal research laboratory in a university research center. SUBJECTS Thirty-eight adult dogs, weighing 20 to 35 kg. INTERVENTIONS Animals were prepared for study with thiopental followed by halothane, diazepam, and pancuronium. Ventricular fibrillation was electrically induced, and after 10 mins, CPR was initiated, including ventilation with an FIO2 of 1.0, manual chest compressions, administration of epinephrine (0.1 mg/kg every 5 mins), and defibrillation. A dose of buffer, equivalent to 1 mmol/kg of NaHCO3, was administered every 10 mins from start of CPR. Animals were randomized to receive either NaHCO3, Carbicarb, THAM, or 0.9% sodium chloride (NaCl). CPR was continued for up to 40 mins or until return of spontaneous circulation. MEASUREMENTS AND MAIN RESULTS Buffer-treated animals had a higher resuscitability rate compared with NaCl controls. Spontaneous circulation returned earlier and at a significantly higher rate after NaHCO3 (in seven of nine dogs), and after Carbicarb (six of ten dogs) compared with NaCl controls (two of ten dogs). Spontaneous circulation was achieved twice as fast after NaHCO3 compared with NaCl (14.6 vs. 28 mins, respectively). Hydrogen ion (H+) concentration and base excess, obtained 2 mins after the first buffer dose, were the best predictors of resuscitability. Arterial and mixed venous Pco2 did not increase after NaHCO3 or Carbicarb compared with NaCl. CONCLUSIONS Buffer therapy promotes successful resuscitation after prolonged cardiac arrest, regardless of coronary perfusion pressure. NaHCO3, and to a lesser degree, Carbicarb, are beneficial in promoting early return of spontaneous circulation. When epinephrine is used to promote tissue perfusion, there is no evidence for hypercarbic venous acidosis associated with the use of these CO2 generating buffers.

Evaluation of the role of ionized calcium in sodium fluoroacetate (“1080”) poisoning

Fluoroacetate, which is an inhibitor of the tricarboxilic acid cycle, is widely used as a rodenticide. Fluoroacetate is converted in the body to fluorocitrate, which is an inhibitor of the enzyme aconitate hydrase. As a result, energy production goes down, and citrate accumulates. As citrate is a potent chelator of calcium ion, we postulated that ionized calcium concentration in the blood would drop. Fluoroacetate, 0.03 mmol/kg, was injected iv into anesthetized cats. Ionized calcium concentration in anaerobically drawn arterial blood samples was measured with an ion-exchange electrode. Samples were taken immediately before and 40 min after the poisoning, after which the animals were either used as controls (six cats) or treated with an infusion of iv CaCl2 (another six cats), so as to restore ionized calcium levels to normal values. Forty minutes after fluoroacetate injection, the ionized calcium levels fell by an average of 27.2%, from 1.09 ± 0.07 to 0.79 ± 0.14 mM. There was a corresponding prolongation of the QTc interval of the ECG (r = 0.82). Treatment with CaCl2 significantly prolonged the life of the treated animals as compared to the control animals (p < 0.0016 by the Mann-Whitney rank sum test). Our findings suggest that reduced levels of ionized calcium play an important role in the pathogenesis of fluoroacetate poisoning. The reduced levels of Ca2+ are an adequate explanation for the toxic effects of fluoroacetate, and may be the missing link between the biochemistry of the poisoning and the clinical manifestations.

Management of crush syndrome

Our experience in treating seven patients with severe crush injury of the lower limbs is described. They were brought to hospital 12 h after rescue and had no treatment until then. All seven developed acute renal failure due to myoglobinuria and dehydration. Five were anuric and three non-oliguric. All developed severe sepsis and two had also acute respiratory failure. No bleeding tendency was observed. They were treated along the following lines: early extensive fasciotomy and removal of dead tissues; early fluid challenge; early peritoneal dialysis and/or hemodialysis; high caloric, high protein nutrition; vigorous antibiotic therapy when infection was evident. There were no deaths in our patients. Our management and results are discussed and compared with those in the literature.

Left ventricular function in patients with acute myocardial infarction, acute pulmonary edema, and mechanical ventilation : relationship to prognosis

ObjectivesTo evaluate the relationship between left ventricular function and prognosis in patients treated with mechanical ventilation for severe, persistent pulmonary edema as a consequence of acute myocardial infarction. DesignA prospective study. SettingA nine-bed coronary care unit in a 900-bed teaching hospital. PatientsSixty-nine successive patients. InterventionsAll patients had acute pulmonary edema not responding to classical treatment and were treated with mechanical ventilation. Measurements and Main ResultsThe inhospital mortality rate was 67%. Thirteen of 23 patients surviving hospitalization died during follow-up, a mean of 5.8 ± 7.7 months after infarction. Six of ten long-term survivors are in functional capacity class 1 or 2 (New York Heart Association) and four survivors are in class 3. Echocardiographic examination indicated that severe left ventricular dysfunction was present in most patients during the time of mechanical ventilation. Repeat echocardiographic examination performed 14.2±8.1 months after infarction showed a remarkable improvement in left ventricular function among the survivors. Multivariate analysis indicated that the small group of patients with a good long-term prognosis could not be separated prospectively from the larger group dying during or after hospitalization using variables obtained at the time of mechanical ventilation. ConclusionsThe mortality rate is high in this group of patients. Left ventricular function of survivors is severely diminished at the time of infarction but improves markedly during follow-up. The small subgroup of patients with a good long-term prognosis cannot be identified prospectively when evaluated during the acute stage of infarction and the provision of mechanical ventilation. (Crit Care Med 1993; 21:380–385)

Early use of naloxone in shock — A clinical trial

Naloxone hydrochloride (N) 0.4-1.2 mg i.v. was administered during 10 episodes of shock (8 septic and 2 cardiogenic) in 9 adult patients. Shock was defined as systolic blood pressure (SBP) less than or equal to 90 mmHg and urine output less than 0.5 ml/h and signs and symptoms of hypoperfusion lasting for greater than or equal to 30 min, despite fluid loading to a CVP 5 cmH2O above baseline. N was given as early as 30 min after onset of shock and resulted in an increase of SBP from a mean of 75 +/- 10 to a mean of 130 +/- 25 mmHg maximum (P less than 0.01). Within 10-60 min urine output increased from 16 +/- 12 to 122 +/- 56 ml/h, heart rate, CVP and arterial blood gas tensions remained unchanged. No side effects were observed. Naloxone, even in small doses, may improve hemodynamic parameters in human shock, provided it is administered very early.

Sodium poisoning: A lethal case of a burned child

An unusual case of lethal salt poisoning of a burned child is presented. Excessive hypernatraemia and hyperosmolality resulted in an irreversible cascade of events which lead to death despite vigorous attempts to rescue the victim.

Early management of severe burns

IN the treatment of burns, immediate and primary management has a marked influence on the mortality rate (Baxter et al., 1974). This consists of: I. Resuscitation. 2. Primary treatment of the burned area. 3. Early excision of eschar and early skin grafting. We wish to present and discuss some elements of the resuscitation stage of treatment, as have been exhibited in a series of 61 mass-injury patients, who were treated for burns during a short time in our centre. The aim in resuscitation is the re-establishment within the shortest time of the normal physiological parameters. This includes cardiorespiratory function, acid-base balance and metabolism.

Central Vein Catheterization. Failure and Complication Rates by Three Percutaneous Approaches

We prospectively studied the results of 714 attempts at central venous catheterization during an eight-month period in our intensive care department. We compared the rates of failure of catheterization and early complications among three percutaneous approaches: subclavian, anterior jugular, and posterior jugular veins. The procedures were performed by experienced staff or resident physicians and inexperienced interns and residents under teaching supervision. Overall rates of failure and complication were similar for each percutaneous approach within each group of physicians. Overall failure rate was 10.1% for the experienced group and 19.4% for the inexperienced. The complication was 5.4% for experienced and 11% for inexperienced. Among inexperienced physicians, the success rate was 86.7% and the complication rate 7.6% in unconscious patients, whereas in conscious patients these rates were 70.5% and 13.8%, respectively. The inexperienced physicians caused fewer complications in mechanically ventilated than in spontaneously breathing patients. We suggest that inexperienced physicians should first attempt central vein catheterizations in unconscious and mechanically ventilated patients.