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Biomedical subjects

M Hilberman

Publications and source records attributed to M Hilberman.

At least 37 records · Page 2Linked to original sources
PubMed1980

Neurologic dysfunction following cardiac operation with low-flow, low-pressure cardiopulmonary bypass.

A prospective 6 month study of all patients undergoing cardiac operation with cardiopulmonary bypass (CPB) was undertaken to determine the incidence of neurologic and neuropsychological dysfunction following low-flow, low-pressure CPB. Among 204 patients who underwent cardiac operation with CPB, there were seven deaths (3.4%), six who developed new motor deficits (2.9%), and 35 (17.2%) who exhibited some neurologic or neuropsychological dysfunction at discharge. When compared to the 169 patients with no evidence of neurlogic or neuropsychological dysfunction at discharge, these 35 were older (65 +/- 10 versus 55 +/- 12 years), had a lower incidence of coronary artery bypass grafting as the sole surgical procedure (29% versus 55%), a higher mortality rate (11.4% versus 1.8%), and prolonged CPB (140 +/- 45 versus 107 +/- 38 minutes). The mean arterial pressure (MAP) during CPB was similar in the two groups (51 +/- 7 versus 49 +/- 7 torr), and an index of time at low pressure, torr x minutes below 50 (TM less than 50), was also similar in the two groups (589 +/- 591 versus 554 +/- 478 TM less than 50). The incidence of postoperative neurologic and neuropsychological complications appears comparable to that in reports from institutions employing high CPB flow and maintaining high CPB MAP. Our results suggest that CPB pressure, per se, is not the major determinant of postoperative neurologic and neuropsychological dysfunction.

Amnesia↗
PubMed1980

Sequential pathophysiological changes characterizing the progression from renal dysfunction to acute renal failure following cardiac operation.

Sequential pathophysiological data were analyzed from 14 patients who exhibited similar severe depression of cardiac and renal function within 24 hours of cardiac operation. Seven patients exhibited postoperative renal dysfunction (defined by a minimum postoperative clearance of inulin [Cin] between 20 ml/min/1.73 m2 and one-half normal) and seven progressed from renal dysfunction to acute renal failure (ARF) (Cin less than or equal to ml/min/1.73 m2). In ARF patients depression of cardiac function was profound and persistent from postoperative days 1 to 7. Urine flow remained greater than 1 ml/min, and serum creatinine rose progressively. The Cin declined progressively during the first postoperative week. The ratio or urinary to plasma osmolality fell, and the fractional excretion of sodium (FENa) and potassium (FEK) increased substantially. By contrast, in renal dysfunction patients definite hemodynamic improvement occurred and renal function remained stable. Increased FENa in renal dysfunction was associated with hemodynamic improvement, weight loss, and stable fractional potassium excretion. These data provide unique documentation of the indices of hemodynamic and renal function associated with the progression to postoperative ARF. The central role of sustained profound depression of cardiac function in this progression appears to be the primary factor in the lethality of postoperative ARF.

Acute Kidney Injury↗
PubMed1979

Transtubular leakage of glomerular filtrate in human acute renal failure.

Ten postcardiac surgical patients with acute renal failure (ARF) were infused with inulin and dextran 40. Plasma and urine were then submitted to gel-permeation chromatography to ascertain the apparent fractional clearance profile for the dextrans. Compared to normal volunteer controls, the fractional clearance profile was substantially elevated for dextran molecules in the Einstein-Stokes radius (r) range 20-40 A. For the smaller molecules (r = 20-28 A), fractional dextran clearance in ARF was frequently in excess of unity. A simple mass conservation model which assumes that the "true" fractional dextran clearance profile for the glomerulus (in Bowman's space) in ARF is the same as that for normal controls, when applied to the experimental observations, revealed that in ARF, on the average, 50% of filtered inulin is lost by tubular backleakage. Furthermore, the model permitted an estimate of the permeability properties of the damaged tubular wall. This indicated tubular permeability not unlike that of the normal glomerulus to dextran molecules with r less than 30 A, but relative impermeability to larger dextran molecules.

Acute Kidney Injury↗
PubMed1979

Acute renal failure following cardiac surgery.

In a prospective 6 month study of 204 patients requiring cardiac operations, five (2.5 percent) developed acute renal failure (ARF) and five (2.5 percent) had documented renal dysfunction (RD). Preoperative left ventricular dysfunction and prolonged cardiopulmonary bypass (CPB) were important predictors of subsequent RD/ARF; CPB pressure per se was not. Physiological and clinical studies in 51 selected patients studied over an 18 month period documented the effectiveness of low flow, low pressure CPB in preserving postoperative renal function. Twenty-two patients with nonazotemic postoperative courses demonstrated moderate depression of cardiac function while the glomerular filtration rate (GFR) was normal (98 +/- 30 ml./min/1.73 M.2) within 24 hours of operation. Seventeen high risk patients developed AFF (65 percent mortality rate) and 12 experienced severe RD without ARF (17 percent mortality). ARF (65 percent mortality rate) and 12 experienced severe RD without ARF (17 percent mortality). Eleven patients with ARF and 11 with RD were studied in the early postoperative period; at this time, all 22 patients demonstrated RD with equivalent severe depression of cardiac and renal function. Superposition of further hemodynamic or toxic insults upon ischemic kidneys was usually necessary for ARF to occur.

Acute Kidney Injury↗
PubMed1976

The effects of carbon dioxide on pulmonary mechanics in hyperventilating, normal volunteers.

Transpulmonary pressure, air flow, and end-tidal carbon dioxide levels were measured in normal human volunteers during hypocapnic, eucapnic, and hypercapnic hyperventilation. Respiratory rate and tidal volumes were well matched at a minute ventilation of 52 L. on three inspired gas mixtures: 21 per cent oxygen and 79 per cent nitrogen; 5 per cent carbon dioxide, 21 per cent oxygen and 74 per cent nitrogen; and 12 per cent carbon dioxide, 21 per cent oxygen and 67 per cent nitrogen. Respiratory rate, tidal volume, lung compliance, resistance, and resistive work per liter were calculated with a digital computer. In 13 experiments in 7 normal volunteers, no net bronchoconstriction or bronchodilatation was observed when eucapnic hyperventilation was compared to hypocapnic or hypercapnic hyperventilation. During hyperventilation of this degree, a change in bronchomotor tone owing to alteration in arterial or alveolar PCO2 either does not occur or else is masked by other reflexes or mechanical factors acting on the bronchi.

Adult↗
PubMed1976

An analysis of potential physiological predictors of respiratory adequacy following cardiac surgery.

More than 50 potential physiological and clinical predictors of postoperative respiratory adequacy were examined in an attempt to identify those few variables which, singly or in combination, best predicted the outcome of the first trial of spontaneous respiration following cardiac surgery. This trial was initiated when patients seemed hemodynamically stable and relatively alert following surgery. Analysis of data from 124 patients identified the following useful predictors: forced vital capacity, total lung capacity, and maximal mid-expiratory flow rate from preoperative pulmonary function tests; resting cardiac index from preoperative cardiac catheterization; postoperative compliance and resistance measured by a computer-based monitoring system; postoperative vital capacity per kilogram, and maximum inspiratory force, measured at the bedside prior to the weaning trial. Stepwise linear discriminant analysis indicated that vital capacity per kilogram and maximum inspiratory force were the most useful predictors, the dividing line between successes and failures being represented by a vital capacity per kilogram of 15 ml. and a maximum inspiratory force of 28 cm. H2O. Mean values of successes were 18.3 +/- 7 ml. per kilogram and 30.7 +/- 9 cm. H2O and, for failures, 11.9 +/- 4 ml. per kilogram and 24.3 +/- 8.4 cm H2O. These physiological variables assess patient effort acting upon an abnormal pulmonary system. Measurements of passive pulmonary mechanics, cardiac function, and the measurement of arterial blood gases were suprisingly poor predictors.

Airway Resistance↗