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Biomedical subjects

R B Hirschl

Publications and source records attributed to R B Hirschl.

119 records · Page 7Linked to original sources
PubMedDate not supplied

The development of an implantable artificial lung.

This report describes the development of an implantable gas exchange device. The device is composed of hollow fiber elements wound around a central open core enclosed in a compliant outer casing, offering very low resistance to blood while providing adequate gas exchange. The purpose of this study was to determine if this device design can completely support the gas exchange requirements of a large animal when the device is placed in series with the main pulmonary artery (PA). Six 40-80 kg adult sheep were used. The device was placed with vascular grafts anastomosed end to side on the proximal and distal main PA. The study began with the entire right ventricular blood flow being diverted through the device by occlusion of a snare around the PA between the vascular grafts. Total gas exchange then was provided by the device and the endotracheal tube was clamped. Results showed that this pumpless potentially implantable device is capable of completely supporting the gas exchange requirements of the experimental animals for up to 8 hours in the acute setting without significant change in cardiac index (CI) and oxygen consumption (VO2) compared with baseline. CI = 55.0 +/- 17.0 cc/min/kg versus 45.0 +/- 17.3 cc/min/kg. VO2 = 1.90 +/- 0.96 cc O2/min/kg versus 2.08 +/- 0.54 cc O2/min/kg.

Animals↗
PubMedDate not supplied

A matched pairs analysis of venoarterial and venovenous extracorporeal life support in neonatal respiratory failure.

It has been suggested that venovenous (VV) extracorporeal life support (ECLS) confers a survival advantage over venoarterial (VA) ECLS. These results have been confounded by differences in patient populations. In this study, a matched pairs comparison of survival and complication rates in neonatal respiratory failure patients managed with VA or VV ECLS was performed. Retrospective matching of 643 VA and VV patient pairs from the Extracorporeal Life Support Organization Registry was performed. Pairs were matched by same year, same diagnosis, gestational age +/- 1 week, birth weight +/- 0.3 kg, and oxygenation index +/- 5. Further matching for hemodynamic status was possible for 272 pairs and included pre ECLS CPR, use of epinephrine, and arterial pH +/- 0.1. Statistical significance was defined for outcome and selected complication rates using McNemar's chi-square analysis with correction for multiple comparisons. A survival advantage for VV was significant when matching for respiratory failure (83.8% VA versus 91.5% VV), but was not significant when matching for hemodynamic failure (90.4% VA versus 94.5% VV). In the latter match, hemolysis (10.7% VA versus 23.5% VV) and cannula kinking (0.4% VA versus 10.6% VV) were more common with VV ECLS. The incidence of intracranial hemorrhage did not significantly differ between groups (6.3% VA versus 7.4% VV). Survival is not significantly greater with VV ECLS when patients are matched for degree of respiratory and hemodynamic failure. Hemolysis and cannula kinking are more common with VV ECLS. There is no identified difference in the incidence of intracranial hemorrhage.

Carotid Arteries↗
PubMedDate not supplied

Extracorporeal life support for cardiovascular support in adults.

The authors retrospectively reviewed their institution's experience with extracorporeal life support (ECLS) for adult cardiovascular failure to determine efficacy and further indications for its use. From 1985 to 1996, venoarterial ECLS was used in 27 adult patients. Indications for ECLS included post cardiotomy cardiac failure, primary myocardial failure, bridge to transplant, and emergency cardiopulmonary resuscitation. The average age was 38.7 +/- 2.7 years and duration of support was 164.0 +/- 26.8 hr. Overall cardiovascular recovery from ECLS was 44%, and hospital survival was 30%. Late deaths were due to multisystem organ failure. Best results were obtained in patients whose processes were reversible during a short duration of ECLS (< 91.6 +/- 33.3 hr. The worst results were obtained in post cardiotomy patients who underwent prolonged support with ECLS. Evaluation of physiologic parameters during the first 30-48 hr of support showed marked improvements from values before ECLS. Because of its relative ease of deployment and its rapid correction of acute physiologic derangements, ECLS can be used as a temporary means of support to determine extent and reversibility of organ dysfunction. Longer term support should include consideration of other mechanical assist devices. The authors no longer consider bridge to transplant an indication for ECLS due to relative donor unavailability.

Adolescent↗
PubMedDate not supplied

Use of the placenta as an artificial lung.

Oxygen transfer across a single cotyledon of the human placenta was assessed by using three different perfusates in the maternal circuit: 1) M-199 culture medium, 2) human adult red blood cells (RBCs), and 3) perflubron. These maternal circuit perfusates were oxygenated with a membrane oxygenator. RBCs were perfused on the fetal side of the circuit and samples were taken preplacenta and postplacenta for each maternal perfusate. PO2 and PCO2 were measured and O2 transfer was calculated for each maternal perfusate. O2 transfer per single cotyledon (mean +/- SE) was 0.18 +/- 0.04, 0.20 +/- 0.03, and 0.15 +/- 0.05 ccO2/min when using: 1) M-199, 2) RBCs, and 3) perflubron, respectively. O2 transfer per kilogram of placental tissue was 13.08 +/- 2.78, 14.57 +/- 2.05, and 10.43 +/- 3.79 ccO2/kg per minute when using: 1) M-199, 2) RBCs, and 3) perflubron, respectively. When extrapolated to the individual weights of the entire placenta, the O2 transfer was 9.15 +/- 1.95, 10.20 +/- 1.43, and 7.30 +/- 2.65 when using: 1) M-199, 2) RBCs, and 3) perflubron, respectively. We conclude from these data that O2 transfer can be accomplished during placental perfusion. Larger studies are required to differentiate efficacy among the three maternal circuit perfusates.

Adult↗
PubMedDate not supplied

Pneumomediastinum: elucidation of the anatomic pathway by liquid ventilation.

Partial liquid ventilation is a new technique to improve oxygenation in patients with severe acute respiratory distress syndrome. In a patient with status asthmaticus and tension pneumothorax treated with subsequent liquid ventilation, radiopaque perfluorocarbon was identified along brochiovascular structures, in the mediastinum, and in the retroperitoneum. Perfluorocarbon outlined on CT and chest radiography the anatomic pathway by which spontaneous pneumomediastinum develops following alveolar rupture, as described earlier by histopathologic study in animals. This represents the radiopaque equivalent of radiolucent pneumomediastinum. Perfluorocarbon remained in the pulmonary interstitium on radiography 30 days after beginning liquid ventilation, without sequelae.

Adult↗
PubMedDate not supplied

Evaluation of Duraflo II heparin coating in prolonged extracorporeal membrane oxygenation.

Adult sized extracorporeal membrane oxygenation circuits were coated with Duraflo II chemical heparin bonding by Baxter-Bentley Laboratories. Five sheep were maintained on venovenous extracorporeal circulation for four days with no systemic anticoagulation. There was no bleeding, no major thrombosis in the circuits, and no significant emboli after 4 days of extracorporeal circulation without anti-coagulation.

Animals↗
PubMedDate not supplied

Partial liquid ventilation in a child on extracorporeal life support.

A 14 month old child was referred for management of acute respiratory distress syndrome after aspiration of paraffin lamp oil. Initial management with conventional ventilation and subsequent management with high frequency oscillatory ventilation produced pulmonary air leaks, further compromising clinical management. After initiating extracorporeal life support and low pressure ventilation, pulmonary air leaks subsided. The patient was then successfully managed by a protocol including partial liquid ventilation with perfluorocarbon. This case report details the authors' experience with the first child with respiratory failure to be managed with partial liquid ventilation while on extracorporeal life support.

Extracorporeal Circulation↗
PubMedDate not supplied

Total respiratory support with tidal flow extracorporeal circulation in adult sheep.

A novel pressure gated tidal flow extracorporeal circulation (TF ECC) device was developed, and it was hypothesized that it could provide total respiratory support in apneic adult sheep without adverse hemodynamic or cardiac effects. The circuit consisted of a single lumen cannula, computer driven tubing occluders gated by circuit pressure, a nonocclusive peristaltic blood pump, a spiral coiled membrane lung, and a heat exchanger. Six paralyzed, anesthetized adult sheep were instrumented and TF ECC was instituted via cannulation of the right atrium. Total respiratory support was provided by the circuit during an apneic period of 6 hours. Echocardiography was performed with the animal instrumented (baseline) and after 2 hours of TF ECC. Circuit blood tidal volume was 172.6 +/- 18.0 cc, resulting in a TF ECC flow of 71.1 +/- 10.1 cc/kg/min. At the end of the study period, PaCO2 was 35.5 +/- 7.6 mmHg, paO2) was 91.2 +/- 30.6 mmHg, and pulmonary artery oxygen saturation (SPAO2) was 95 +/- 5%. Hemodynamic stability was maintained with no significant differences at baseline and after 6 hours in mean arterial pressure, mean pulmonary artery pressure, or heart rate noted. Echocardiographic evaluation showed preserved fractional shortening of the left ventricular (LV) septal-lateral dimension (baseline 32.4 +/- 11.4%; 2 hours 34.8 +/- 8.4%). This study demonstrates TF ECC provides total respiratory support without adverse hemodynamic effects, and preserved LV function.

Animals↗