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Biomedical subjects

M Mathru

Publications and source records attributed to M Mathru.

32 records · Page 2Linked to original sources
PubMed1986

Use of sodium nitroprusside in post-coronary bypass surgery. A plea for conservatism.

In 292 patients who underwent coronary artery bypass graft (CABG) surgery, seven patients developed sodium nitroprusside (SNP) toxicity in the postoperative period. Duration of infusion varied between 26 to 160 hrs and total SNP dose ranged from 1.8 to 12 mg/kg body weight. All patients were critically ill and required ventilatory support in the postoperative period. Tachyphylaxis to SNP requiring increase of SNP dose for control of hypertension, and loss of consciousness were the major signs of toxicity. Other commonly described signs of SNP toxicity were absent in those patients. Discontinuation of SNP therapy and treatment with sodium thiosulfate was followed by improvement in four patients. Three patients who failed to regain consciousness later died because of hemodynamic, pulmonary and/or renal complications. Our observation suggests that recommended doses of SNP may be toxic in unstable post-CABG patients. We recommend that the dose and duration of SNP infusion be minimized in critically ill patients.

Aged↗
PubMed1985

Renal function during application of positive end-expiratory pressure in swine: effects of hydration.

The possibility that the deleterious renal effects of positive end-expiratory pressure (PEEP) might be avoided by prevention of its attendant cardiovascular effects with increasing intravascular volume was investigated in two groups of anesthetized swine. Group 1 (12 swine) were maintained at a normovolemic state and Group 2 (11 swine) were volume expanded with an infusion of lactated Ringer's solution. In normovolemic swine (Group 1), the addition of PEEP to controlled mechanical ventilation (CMV) caused significant decreases in cardiac output and mean aortic pressure. In addition, decreases in urinary output and osmolar, free water, and creatinine clearance occurred. Change from CMV to CMV + PEEP in Group 1 also produced increases in plasma ADH from 4.6 +/- 2.4 to 10.2 +/- 7 pg/ml (P less than 0.01) and renin from 1.8 +/- 1.0 to 4.7 +/- 1.6 ng X ml-1 X h-1 (P less than 0.01), epinephrine from 133 +/- 23 to 1,060 +/- 636 pg/ml (P less than 0.03) and norepinephrine from 46 +/- 15 to 1,427 +/- 839 pg/ml (P less than 0.03). In hydrated swine (Group 2) addition of PEEP to CMV was not accompanied by any significant change in hemodynamic, renal, or hormonal variables. It is concluded that the short-term renal effects of PEEP are mainly due to hormonal responses that are activated by decrease in perfusion pressure. These responses can be obviated by intravascular volume expansion.

Animals↗
PubMed1985

Cardiac electrophysiologic effects of pancuronium.

A microelectrode examination of guinea pig left ventricular papillary muscle was performed to determine whether there was a direct effect of pancuronium on cardiac cells and, if so, to attempt to ascertain the mechanism of this effect. Electrical events were measured before and during superfusion with pancuronium, epinephrine, propranolol, and verapamil; alone and in various combinations. Pancuronium prolonged the duration of the action potential (AP); increased resting potential (Em), AP magnitude, and rate of rise of the AP (dV/dt); and resulted in spontaneity in 12% of the muscles. Epinephrine and pancuronium combined caused spontaneity in 80% of the muscles and oscillatory behavior. Additionally, this combination decreased AP magnitude, Em, and dV/dt in several preparations--a pattern of response similar to that seen in ouabain-treated myocardial cells under the influence of catecholamines. These changes were always reversed by verapamil or by perfusion with a drug-free medium, and were usually reversed by propranolol. The data suggest a combined pancuronium/epinephrine induced increase in cardiac membrane permeability to Ca2+.

Action Potentials↗
PubMed1984

Hemodynamic alterations in canine acute lung injury induced with N-nitroso-N-methylurethane.

Acute alveolar injury induced by subcutaneous injection of N-nitroso-N-methylurethane (NNNMU) closely resembles the pathology of human adult respiratory distress syndrome (ARDS). However, its effects on cardiovascular function have not been evaluated. We measured hemodynamic variables and venous admixture (Qsp/Qt at FIO2 0.21) and shunt fraction (Qsp/Qt at FIO2 1.0) in 7 dogs. The measurements were repeated when a single subcutaneous injection of 8.0 mg/kg NNNMU decreased PaO2 on room air to 40 torr (phase I) and 30 torr (phase II). Within 5 to 7 days after injection, PaO2 decreased to 40 torr, Qsp/Qt at FIO2 0.21 increased from 0.18 to 0.70, Qsp/Qt at FIO2 1.0 increased to 0.55, and pulmonary vascular resistance index (PVRI) increased from 213 +/- 37 to 407 +/- 142 dyne X sec/cm5 X m2 (p less than .05). However, a decrease in mean arterial pressure (MAP) from 153 +/- 16 to 131 +/- 32 mm Hg was the only significant hemodynamic change. At phase II, decreased systemic vascular resistance index (SVRI) was the only significant hemodynamic alteration. We conclude that single subcutaneous injection of NNNMU produces hemodynamic and pulmonary dysfunction similar to that seen in human ARDS. This acute lung-injury model may be useful for evaluating different ARDS therapies.

Animals↗
PubMed1984

Comparison of the sterility of long-term central venous catheterization using single lumen, triple lumen, and pulmonary artery catheters.

The incidence of thrombocytopenia and catheter-induced infection and colonization after the use of triple lumen (TLC), pulmonary artery (PA), and single lumen central venous (CVP) catheters was studied in 29 critically ill patients. Catheter-induced sepsis was documented in 7% of patients with TLC and 10% of patients with CVP and PA catheters. Thirty-three percent of TLC, 20% of PA and 10% of CVP catheters became contaminated during the study. Staphylococcus epidermidis most commonly caused catheter sepsis and contamination. Only patients with PA catheters showed significant decrease in their platelet count. We conclude that use of TLC catheters in critically ill patients does not appear to increase the risk of infectious disease and thrombocytopenia.

Aged↗
PubMed1983

Ventilator-induced barotrauma in controlled mechanical ventilation versus intermittent mandatory ventilation.

Retrospective analysis of pulmonary barotrauma incidence in 292 patients ventilated greater than or equal to 24 h was conducted. From 1971-1973, 156 patients with acute respiratory insufficiency were managed with controlled mechanical ventilation (CMV) and PEEP. During 1973-1976, 136 patients were supported with IMV and CPAP. Despite higher mean peak and end-expiratory airway pressure, the IMV-CPAP group exhibited a significantly lower incidence of ventilator-induced barotrauma; 7% vs 22% (p less than 0.01). We suspect the difference is related to fewer mechanical breaths with IMV and not to the level of end-expiratory pressure employed.

Barotrauma↗
PubMed1983

Noncardiac pulmonary edema precipitated by tracheal intubation in patients with inhalation injury.

Ten patients with body surface burn and clinical evidence of inhalation injury developed transient, reversible pulmonary edema within 5 min after endotracheal intubation. Hemodynamic studies within 1 hr after intubation revealed normal cardiac output and pulmonary artery wedge pressure (WP). Additionally, in the latter 4 patients, protein concentration of edema fluid (EF) aspirated from the trachea was 58-104% of plasma (P) total protein. These findings suggest that altered capillary permeability was responsible for this transient pulmonary edema. It is postulated that glottic generated expiratory retard may increase alveolar pressure, thus preventing pulmonary edema. Bypass of glottis by tracheal intubation may render alveolar pressure atmospheric and facilitate edema formation.

Adolescent↗
PubMed1982

Hemodynamic response to changes in ventilatory patterns in patients with normal and poor left ventricular reserve.

Hemodynamic effects of controlled mechanical ventilation (CMV), intermittent mandatory ventilation (IMV), and intermittent mandatory ventilation with 5 cm H20 PEEP (IMV 5 peep) were studied in 20 patients after aortocoronary bypass surgery. Significant increases in cardiac index (CI) and stroke volume index (SI) (p less than 0.01) resulted in patients with normal left ventricular end-diastolic pressure (LVEDP) and ejection fraction (EF) changing from CMV to IMV. With a change from IMV to IMV 5 peep, the CI and SI returned to CMV values. However, in patients with increased LVEDP with an EF of less than 0.6, suggesting poor ventricular function and reserve, when the mode of ventilation was changed from CMV to IMV, right atrial pressure (RAP) and pulmonary artery occlusion pressure (PAOP) significantly increased (p less than 0.01) with an associated significant decrease in mean arterial pressure (MAP), CI, SI (p less than 0.01). When these patients were placed on IMV 5 peep, the hemodynamic variables returned to the values obtained during CMV. We conclude that changing from CMV to IMV has salutory effects on the patient's hemodynamic values with normal left ventricular function. But in patients with failing left ventricle, volume overload of right ventricle which occurs with the institution of spontaneous respiration during IMV has deleterious effects on the hemodynamic variables. These deleterious effects can be effectively negated by the application of IMV 5 peep.

Blood Pressure↗
PubMed1981

Prophylactic intubation and continuous positive airway pressure in the management of inhalation injury in burn victims.

Burn mortality statistics are influenced by age and degree of total surface body burn. The addition of an inhalation injury to a cutaneous burn results in a significant increase in mortality rate. Nine hundred fourteen patients with acute thermal injury were screened for positive history of burn in a closed space, facial or oropharyngeal burn, singed nasal vibrisae, carbonacious sputum, and clinical signs of upper airway involvement. On admission, 84 patients (9.2%) had more than one of the previously mentioned factors. They were prophylactically intubated and placed on optimum level of continuous positive airway pressure (CPAP) and intermittent mandatory ventilation (IMV). The mortality rate among patients without inhalation injury was 7.1%, while 54.7% of patients with inhalation injury died. Comparison of burn patients with inhalation injury to those without pulmonary involvement at the same age group and with the same percentage of burn showed significantly higher mortality rate in patients with inhalation injury. The main cause of death in the first 72 h postburn (stage 1) in patients without inhalation injury was peripheral shock (10.1%) and in patients with inhalation injury was peripheral shock (15.2%) and cardiac failure (10.8%). No pulmonary related death occurred in this stage. In 3-10 days postburn period (stage 2), burn wound sepsis (10.1%) and cardiac failure (11.8%) were the major causes of death in patients with inhalation injury. In patients with inhalation injury, pulmonary sepsis (26%) was the major cause of death in this stage. Major causes of death after 10 days postburn (stage 3) in patients without inhalation injury were pulmonary sepsis (20%) and burn wound sepsis (22%). In patients with inhalation injury, burn wound sepsis (21.7%) was the main cause of death. These data suggest that prophylactic intubation and CPAP therapy in burn patients with suspected inhalation injury prevent pulmonary related death in early stage of burn. Irrespective of presence of inhalation injury, sepsis originating from the wound or respiratory tract is the main cause of death in the late stage of burn.

Adolescent↗