Paul R. Liebman

Hepatic--portal venous gas in adults: etiology, pathophysiology and clinical significance.

The roentgenographic finding of hepatic-portal venous gas (HPVG) has been reported extensively in the pediatric and radiology literature. The surgical implications and clinical significance have yet to be fully defined. This study reviews the 60 reported cases in the literature and adds four new cases. HPVG appears as a branching radiolucency extending to within 2 cm of the liver capsule. HPVG is associated with necrotic bowel (72%), ulcerative colitis (8%), intra-abdominal abscess (6%), small bowel obstruction (3%), and gastric ulcer (3%). Mucosal damage, bowel distention and sepsis predispose to HPVG. The current mortality rate of 75% represents an improvement from previous experience. Analysis of survivors indicates that the finding of HPVG requires urgent surgical exploration except when it is observed in patients with stable ulcerative colitis.

The Association of Lung Distention, Peep and Biventricular Failure

Although positive and expiratory pressure (PEEP) is known to depress the cardiac output, the mechanism remains debated. Two series of experiments were designed to explore this mechanism. In the first study, the application of 15 cm H2O of PEEP to nine anesthetized, ventilated dogs led to a reduction of cardiac index from (mean ± one standard error of the mean) 2.71 L/min m ± 0.35 to 2.19 L/min m ± 0.22 (p <.05) and a drop in mean arterial pressure (MAP) from 117 mm Hg ± 8 to 91 mm Hg ± 11 (p <.01). The mean net (vascular minus pleural pressure) pulmonary artery pressure (MPAP) rose from 15.3 mm Hg ± 1.2 to 20.6 mm Hg ± 1.8 (p <.02). The mean net central venous pressure (CVP) rose from 5.2 mm Hg ± 0.9 to 8.4 mm Hg ± 0.9 (p <.05) and the net pulmonary arterial wedge pressure (PAWP) rose from 6.7 mm Hg ± 0.7 to 9.5 mm Hg ± 0.9 (p <.01). There was a nonsignificant rise in the mean net left atrial pressure (LAP). As PEEP was raised in increments from 0 to 20 cm H2O, both LAP and PAWP increased. The rise in PAWP was always greater than the increase in LAP. The difference between PAWP and LAP was strongly correlated with the increase in MPAP (r = 0.98). This relationship was useful in correcting the PAWP during PEEP. The problem of cardiac depression was evaluated in a second series of eight dogs. These animals underwent complete chest wall excision to eliminate any possible direct effects of increased pleural pressure on the heart and great vessels. The absence of the chest wall permitted hyperexpansion of the lungs, particularly with positive end expiratory pressure. At 15 cm H2O of PEEP, the mean cardiac index fell in these animals from 2.36 L/min m± 0.26 to 1.47 L/min m± 0.18 (p <.01) and the MAP fell from 105 mm Hg ± 16.2 to 68 mm Hg ± 4.8 (p <.001). The CVP rose from a mean of 5.5 mm Hg ± 0.4 to 8.3 mm Hg ± 0.6 (p <.01) and the LAP rose from 6.3 mm Hg ± 0.8 to 8.0 mm Hg ± 1.1 (p <.05). The MPAP rose from 18.0 mm Hg ± 0.6 to 23.3 mm Hg ± 1.6 (p <.01). Comparison of Group I and II showed a significantly greater depression of the cardiac output and MAP in the open-chested animals. At the same time LAP was significantly higher. These data strongly suggest that PEEP and particularly pulmonary hyperinflation induce biventricular failure.

Humorally Mediated Alterations in Cardiac Performance as a Consequence of Positive End-Expiratory Pressure

Two experimental designs were used to study the mechanism of the decreased cardiac output associated with the use of positive end-expiratory pressure (PEEP). In the first study of nine dogs the application of 15 cm H2O PEEP led to a decrease in cardiac output (CO) from 2.68 +/- 1.05 to 2.01 +/- 1.26 liters/min (+/- SD) (p less than 0.05) concomitant with an increase in transmural central venous pressure of 5.2 +/- 0.9 to 8.4 +/- 2.7 mm Hg (p less than 0.05) and a slight increase in transmural left atrial pressure of 6.8 +/- 3.3 to 7.3 +/- 3.6 mm Hg (p less than 0.1). These data are consistent with altered ventricular performance. In a second study nine pairs of dogs were cross-circulated. Application of 15 cm H2O PEEP to one member of the experimental pair led to a decrease in the CO of the other member from 2.71 +/- 0.98 to 2.21 +/- 0.81 liters/min (p less than 0.001). This decrease returned toward baseline with the removal of PEEP (p less than 0.02). Results indicate that one mechanism whereby PEEP reduces the cardiac output is through the action of a humoral agent.

A method for direct coronary sinus flow measurement and blood sampling in the dog.

Various methods for sampling and measurement of coronary sinus flow in animals have been reported. All have disadvantages because of the need for fluoroscopy or for special tubing or equipment. A technique using readily available materials is described that provides direct measurement of coronary sinus blood flow and allows coronary sampling.

New tube for the diagnosis and treatment of upper gastrointestinal hemorrhage.

Abstract The design, use, and applications of a new tube for the treatment and diagnosis of upper gastrointestinal hemorrhage are presented. The tube incorporates suction, air sump, and irrigating components in a triple-lumen construction. The tube allows constant irrigation of the bleeding stomach with large quantities of irrigant that may contain antacids, vasoconstrictors, or both. The efficient evacuation of the stomach may result in more productive gastroscopy and upper gastrointestinal roentgenographic examinations. The tube can provide early warning of rebleeding as well as perhaps providing definitive or temporizing therapy in some cases of bleeding.