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Biomedical subjects

R B Hirschl

Publications and source records attributed to R B Hirschl.

At least 109 records · Page 6Linked to original sources
PubMed1994

Splenic enlargement in neonates during ECMO.

PURPOSE: To determine whether hepatosplenomegaly was a reproducible finding in seven neonates who were being treated with extracorporeal membrane oxygenation (ECMO) for respiratory failure. MATERIALS AND METHODS: The authors measured splenic and hepatic dimensions with ultrasound (US) at the time ECMO was initiated and then every 24-48 hours until decannulation. Splenic volume and the index of hepatic size were calculated by using published formulas. RESULTS: Splenic volume increased in all seven patients from 8.3 cm3 +/- 1.7 to 16.4 cm3 +/- 4.4 (P < or = .001). Hepatic size did not change markedly. CONCLUSION: Hemolysis, leukopenia, and platelet activation occur during ECMO. Rapid splenic enlargement may be secondary to sequestration of red cells, platelets, and other hematologic elements that have been damaged in the ECMO circuit. Since the liver does not also increase in size, the splenic enlargement is unlikely to be the result of passive congestion.

Extracorporeal Membrane Oxygenation↗
PubMed1994

Lung management with perfluorocarbon liquid ventilation improves pulmonary function and gas exchange during extracorporeal membrane oxygenation (ECMO).

We investigated whether pulmonary function and gas exchange would improve with liquid perfluorocarbon ventilation (LV) during ECMO for severe respiratory failure. Lung injury was induced in 11 young sheep 15.1 +/- 3.7 kg in weight utilizing right atrial injection of 0.07 cc/kg oleic acid followed by saline pulmonary lavage. When (A-a)DO2 > or = 600 mmHg and PaO2 < or = 50 mmHg with FiO2 = 1.0, ECMO was instituted. Animals were then ventilated with either standard ECMO "lung rest" gas ventilator settings (ECMO, n = 5) or with "total" liquid ventilation at standard ventilator device settings (LIQ-ECMO, n = 6) utilizing perflubron (perfluooctyl bromide, Liquivent; Alliance Pharmaceutical Corp.). After 3 hours on ECMO, pulmonary physiologic shunt decreased (ECMO = 88 +/- 11% vs LIQ-ECMO = 31 +/- 1%; p < .001) and pulmonary compliance increased (ECMO = 0.50 +/- 0.06 cc/cmH2O/kg vs. LIQ-ECMO = 1.04 +/- 0.19 cc/cmH2O/kg; p < .001). The ECMO flow rate required to maintain the PaO2 in the 50-80 mmHg range was decreased significantly (ECMO = 116 +/- 14 ml/kg/min vs. LIQ-ECMO = 14 +/- 5 ml/kg/min; p < .001). In this model requiring extracorporeal support for severe respiratory failure, lung management with liquid ventilation improves pulmonary function and gas exchange.

Animals↗
PubMed1994

Liquid ventilation provides uniform distribution of perfluorocarbon in the setting of respiratory failure.

BACKGROUND: We evaluated the effect of perfluorocarbon liquid ventilation (LV) on gas exchange and pulmonary function in the setting of respiratory failure and the distribution of the ventilating medium during LV when compared to gas ventilation (GV). METHODS: Ten sheep, 17.3 +/- 4.2 kg in weight, underwent oleic acid induction of lung injury followed by either GV (n = 5) or perfluorocarbon LV (n = 5). After 1 hour animals were killed, and chest computed tomographic (CT) imaging was performed. Average CT attenuation number was assessed as an indicator of the distribution of gas or perfluorocarbon in the dependent (posterior) and nondependent (anterior) zones of the lung (air = -1000; soft tissue = 0; perfluorocarbon = +2300 Hounsfield units [H]). RESULTS: Significant increases in PaO2 (LV = 298 +/- 76 mm Hg, GV = 43 +/- 18 mm Hg, p < 0.001), SvO2 (LV = 74% +/- 6%, GV = 32% +/- 18%, p < 0.01), and lung compliance (LV = 1.65 +/- 0.50 ml/cm H2O/kg, GV = 0.58 +/- 0.06 ml/cm H2O/kg, p < 0.01) were observed. Significant decreases in physiologic shunt (LV = 24% +/- 6%, GV = 62% +/- 14%, p < 0.01) were noted. CT attenuation data showed the presence of minimal gas ventilation in the dependent regions during GV although the nondependent regions remained well aerated (CT attention number during GV: ND = -654 +/- 160 H; D = -92 +/- 160 H, p < 0.0001). During LV, there was a fairly homogenous distribution of perfluorocarbon in the lungs (CT attenuation number during LV: D = 1071 +/- 330 Hounsfield units; ND = 1112 +/- 287 Hounsfield units; p = 0.240). Lung biopsy analysis in the LV animals was consistent with a reduction in intraalveolar hemorrhage, intraalveolar edema, and the inflammatory infiltrate. CONCLUSIONS: On the basis of the data, we conclude that in this lung injury model, (1) the distribution of the ventilating medium is uniform during LV when compared to GV, (2) LV improves gas exchange and pulmonary function, and (3) histologic evidence of lung injury is reduced after LV when compared to GV.

Animals↗
PubMed1994

Definitive treatment of Hirschsprung's disease in the newborn with a one-stage procedure.

BACKGROUND: The purpose of this study was to review our experience and early follow-up with 15 one-stage pull-through procedures performed at the time of diagnosis in neonates and infants with Hirschsprung's disease. METHODS: Historic chart review of all patients with the new diagnosis of Hirschsprung's disease seen at the C.S. Mott Children's Hospital at the University of Michigan, Ann Arbor, between June 1989 and June 1992 was performed. Progress notes, operative and anesthetic records, pathology reports, and outpatient follow-up notes were used for data collection. RESULTS: Operative technique included a modified endorectal pull-through after determining the presence of ganglion cells by frozen section. No colostomies were performed before or after operation. Three patients had affected family members. All infants were born at term. Operation was performed within 24 hours of diagnosis and as early as 48 hours of age. Twelve patients had standard rectosigmoid disease, two had total colonic disease, and another had long-segment disease. Bowel function returned within 4 days of operation, and feeding was instituted by postoperative day 6 in all patients. All of the patients with rectosigmoid disease are doing well. Patients with long-segment or total colonic disease had more problems but are currently at home and doing well. Morbidity included two postoperative bowel obstructions and three patients with postoperative enterocolitis. CONCLUSIONS: A single definitive operation may be used to treat Hirschsprung's disease diagnosed in the newborn. Long-term follow-up in these patients is required.

Female↗
PubMed1993

Oxygen consumption and carbon dioxide production during liquid ventilation.

Liquid ventilation with perfluorocarbon (PFCV) has advantages over conventional gas ventilation (GV) in premature and lung-injured newborn animals. Indirect calorimetric measurement of both oxygen consumption (VO2) and carbon dioxide production (VCO2) during PFCV has not been previously performed. In addition, comparison to indirect calorimetric measurement of VO2 and VCO2 during GV has not been evaluated. Ten fasted normal cats weighing 2.6 to 3.9 kg were anesthetized with pentobarbital and pancuronium. Tracheostomy was performed. Gas exchange was measured across the native lung during GV and across the membrane lung of the liquid ventilator during PFCV. VO2 was measured using a modification of a previously described, indirect, closed-circuit, volumetric technique. VCO2 was analyzed by capnographic assay of the mixed-expired closed-circuit air. The VCO2/VO2 ratio (RQ) was calculated. There was no change in VO2, VCO2, or RQ during PFCV when compared with GV (VO2: GV = 5.7 +/- 0.3 mL/kg/min, PFCV = 5.6 +/- 0.5 mL/kg/min [P = NS]; VCO2: GV = 4.9 +/- 1.1 mL/kg/min, PFCV = 4.8 +/- 0.9 mL/kg/min [P = NS]; RQ: GV = 0.85 +/- 0.21, PFCV = 0.86 +/- 0.21 [P = NS]). During GV the PaO2 was higher than during PFCV (PaO2: GV = 335 +/- 70 mm Hg, PFCV = 267 +/- 83 mm Hg [P = .04]), as is expected because of the relative reduction in the inspiratory PiO2 of the perfluorocarbon during liquid ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Mesenteric ischemia in hypoplastic left heart syndrome.

Hypoplastic left heart syndrome (HLHS) has been widely viewed as a uniformly fatal form of congenital heart disease. Between January 1984 and December 1990, 387 patients with the diagnosis of HLHS were treated at this institution. Mesenteric ischemia was clinically diagnosed in 31 patients (8% incidence) and confirmed by pathology or surgery in 25 of those patients. The mean age at the time of onset was 17.5 +/- 5.4 weeks and only 13% were premature newborns. In 80% of the patients a low perfusion state and significant hypotension were documented within 48 hours prior to the diagnosis of bowel ischemia. Nine patients (29%) required operative intervention (bowel resection 4, diffuse ischemia 3, and simple drainage 2). Overall, at operation or at autopsy, nine patients (29%) had diffuse gastrointestinal ischemia. Of 31 patients with mesenteric ischemia, 26 children (84%) died shortly after onset of the gastrointestinal symptoms regardless of means of management. Five patients (10%) initially improved with aggressive medical and/or surgical management; however, 4 subsequently died secondary to complications of their primary cardiac disease. Therefore, the overall mortality of patients with mesenteric ischemia was 97%. Previous reports have estimated that up to 7% of full-term newborns with symptomatic congenital heart disease may develop necrotizing enterocolitis (NEC). Our unique group of patients with HLHS is comprised mostly of full-term infants who developed onset of mesenteric ischemia at a mean age of 4 months associated with an underlying low perfusion state. This mesenteric ischemia has been erroneously identified as NEC.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis, Differential↗
PubMed1993

Evaluation of the right atrial venous oxygen saturation as a physiologic monitor in a neonatal model.

Pulmonary artery (PA) mixed venous saturation (SvO2) has become a crucial monitor in the adult intensive care unit, but is not used in neonates because of the difficulty in PA catheterization. We evaluated the possibility of utilizing the right atrial venous oxygen saturation (RAvO2), which is easily accessed in the neonate, as a monitor of the effects of mechanical ventilation and intravascular volume in an animal model selected to be the size of the human neonate. A continuous RAvO2 monitoring catheter was placed into the right atrium of 16 normal rabbits (2.2 to 4.1 kg). Oxygen delivery was manipulated by alterations in peak inspiratory pressure (PIP) (n = 6), positive end-expiratory pressure (PEEP) (n = 6), or by progressive hypovolemia (n = 4). RAvO2 decreased with onset of mechanical ventilation alone from 69% +/- 6% to 61% +/- 5% (P < .01). As the PIP was increased from 12 to 21 cm H2O, the RAvO2 progressively decreased from 59% +/- 4% to 49% +/- 6% (P < .05). As the PEEP was increased from 3 to 9 cm H2O, the RAvO2 progressively decreased from 64% +/- 5% to 33% +/- 16% (P < .01). RAvO2 approached baseline after return to continuous positive airway pressure (CPAP) of 3 cm H2O. Progressive phlebotomy to a total of 10 mL/kg resulted in a decrease in RAvO2 from 70% +/- 6% to 27% +/- 5% (P < .001). Volume resuscitation resulted in an increase in RAvO2 to near baseline. Peripheral arterial oxygen saturation remained at a constant 100% throughout each protocol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The efficacy of extracorporeal life support in premature and low birth weight newborns.

Based on data obtained early in the development of neonatal extracorporeal life support (ECLS), contraindications to the use of ECLS have included low estimated gestational age (EGA) and low birth weight (BW). However, multiple improvements in the technical and management aspects of neonatal ECLS have been implemented since those early data were evaluated. The purpose of this study, therefore, is to assess in the "modern era" the efficacy of prolonged extracorporeal support in premature and low birth weight newborns. Examination of the Extracorporeal Life Support Organization (ELSO) Registry showed that between 1988 and 1991 ECLS was utilized in 158 premature (PREM, EGA < or = 34 weeks), 4,128 full-term (FT, EGA > or = 35 weeks), 26 low birth weight (LBW, BW < 2.0 kg), and 4,333 normal birth weight (NBW, BW > or = 2.0 kg) patients with respiratory failure. Data were evaluated for variables thought to be associated with a decrease in survival or an increase in the incidence of intracranial hemorrhage (ICH). A logistic regression model was developed to evaluate the ability of EGA and BW to predict survival. The incidence of survival (SURV) was decreased (63% v 84%) and ICH increased (37% v 14%) significantly in PREM when compared with FT newborns (P < .001). However, respectable survival rates in PREM patients with EGA > 32 weeks were documented. In addition, both survival and ICH in PREM patients have improved substantially when compared with past reports (Past: SURV = 25% and ICH = 100%; current: SURV = 63% and ICH = 37%; ICH P < .001; SURV P = .056). Survival was significantly decreased in LBW when compared to NBW neonates (65% v 83%, P < .05), but there was no significant difference in ICH.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1993

Inflammatory bowel disease.

Inflammatory bowel disease in children encompasses at least two forms of intestinal inflammation: ulcerative colitis and Crohn's disease. These two disease processes are differentiated based on clinical presentation, radiologic findings, endoscopic findings, histologic evaluation, and exclusion of alternative causes. The treatment and operative interventions are reviewed.

Child↗
PubMed1992

Severe myocardial dysfunction during extracorporeal membrane oxygenation.

Of the 102 neonates with respiratory failure supported with extracorporeal membrane oxygenation (ECMO) at this institution between 1984 and 1987, 8 patients developed severe myocardial dysfunction that was noted shortly after onset of bypass. The neonates in the cardiac dysfunction group were more hypoxic (average PaO2 = 26 +/- 8 mm Hg v 41 +/- 19 mm Hg, P less than .01) in the immediate pre-ECMO period. Seventy-five percent were unstable hemodynamically (6 hypotensive, 3 bradycardic, 2 sustained cardiac arrest, 4 required epinephrine pressor support). On ECMO, 5 of the 8 neonates developed an ischemic cardiomyopathy that lasted for less than 24 hours and resolved without therapeutic intervention. In the other 3 cases, prolonged periods of dysfunction were noted and afterload reduction through administration of tolazoline or hydralazine was beneficial. These 8 patients serve to demonstrate the reversible nature of postischemic cardiac dysfunction in patients on ECMO and in the neonatal population in general.

Electrocardiography↗
PubMed1992

Oxygen kinetics in experimental sepsis.

Systemic oxygen delivery (DO2) is normally four to five times higher than oxygen consumption (VO2), and VO2 is independent of DO2. If DO2 is decreased to less than twice VO2, a state of anaerobic metabolism and supply dependency occurs. Some authors have reported that this biphasic relationship is altered in the adult respiratory distress syndrome or sepsis to a condition of continuous supply dependency. If that were true, it would affect both our understanding and management of metabolism during sepsis. Therefore we measured VO2 and DO2 in a dog peritonitis model. DO2 was regulated with controlled pericardial tamponade. During sepsis VO2 increased 28% from a mean baseline of 5.6 to 7.3 cc O2/kg/min (p less than 0.005). As progressive cardiac tamponade was applied during sepsis, the DO2/VO2 ratio fell. When the DO2/VO2 ratio was greater than 2.4, VO2 remained independent of DO2. At DO2/VO2 ratios less than 2.4, VO2 was dependent on the level of DO2, and it diminished rapidly as DO2 decreased. Oxygen saturation in mixed venous blood (SvO2) consistently reflected the DO2/VO2 ratio in a fashion similar to that in normal dogs. A ratio of DO2/VO2 of 2.4 corresponded with an SvO2 of 42% +/- 12%, which was identified as a statistically significant critical SvO2 that marked onset of VO2 supply dependence. In this dog septic model, VO2 is independent of DO2 when DO2 is adequate. A state of continuous supply dependency does not exist. SvO2 reflects the status of the DO2/VO2 relationship in the septic state.

Animals↗
PubMed1992

Diagnosis-related criteria in the consideration of extracorporeal membrane oxygenation in neonates previously treated with high-frequency jet ventilation.

High-frequency jet ventilation (HFJV) is one of several high-frequency techniques that are particularly valuable for treating the neonate with lung disease refractory to conventional ventilation or with pulmonary air leak. Extracorporeal membrane oxygenation (ECMO) has also emerged as a valuable rescue therapy for neonates of more than 2000 g birth weight and 34 weeks' gestation with intractable respiratory failure. With the concurrent introduction of HFJV and ECMO, the authors sought to evaluate the role of HFJV prior to the institution of ECMO therapy. The data base for 2856 neonates receiving mechanical ventilation in one unit was used to identify 73 (of 298 total) neonates treated with HFJV, who were eligible by age and weight criteria for ECMO. Patients were grouped by diagnosis, and the oxygenation index (OI) was calculated during therapy. Outcome was evaluated for mortality, and the sensitivity of the OI for predicting mortality was calculated. Neonates who survived with HFJV alone presented with an OI of 0.30 +/- 0.03 (SEM), significantly less than nonsurvivors (0.42 +/- 0.04, P = .016). Survivors responded to HFJV with a rapid decrease in OI at 1 hour (0.19 +/- 0.02, P less than .001) and 6 hours (0.15 +/- 0.01, P less than .001). Nonsurvivors did not respond significantly at 1 hour (OI = 0.33 +/- 0.04, P = not significant [NS]) or at 6 hours (OI = 0.40 +/- 0.06, P = NS). By diagnosis, neonates with respiratory distress syndrome survived more often with HFJV (28/34, 82%) than neonates with meconium aspiration (10/26, 38%) or diaphragmatic hernia (3/9, 33%). Neonates with respiratory distress syndrome seldom presented with high OI values, but the majority of those who did survived (5/7 survived with initial OI greater than or equal to 0.40).(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1991

Plasma prostanoids in neonates with pulmonary hypertension treated with conventional therapy and with extracorporeal membrane oxygenation.

Thromboxane may be a mediator of pulmonary hypertension in the neonate. Acute thromboxane-mediated pulmonary hypertension has been described in sheep receiving extracorporeal membrane oxygenation, which raises concerns about a potential thromboxane-mediated exacerbation of pulmonary hypertension in human neonates with severe pulmonary hypertension who are treated with extracorporeal membrane oxygenation. We measured plasma levels of thromboxane, prostaglandin F2 alpha, and 6-keto-prostaglandin F1 alpha in infants with pulmonary hypertension, some of whom were treated medically and some of whom were treated with extracorporeal membrane oxygenation. Plasma levels of all three prostanoids were elevated in infants with pulmonary hypertension and decreased with time, whether the neonates were treated with extracorporeal membrane oxygenation or with medical management alone. In infants treated with extracorporeal membrane oxygenation, we collected samples simultaneously from preoxygenator sites, postoxygenator sites, and umbilical artery catheter. We could demonstrate no significant difference in plasma prostanoid levels across the oxygenator. In two patients, plasma thromboxane and prostaglandin F2 alpha levels measured shortly after a platelet transfusion were distinctly higher in the umbilical artery catheter than in venous samples.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Life-threatening intrathoracic complications during treatment with extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) has been successful (greater than 80% survival) in 35 centers in greater than 900 newborns with severe respiratory failure having an estimated mortality of greater than 80% on conventional management. During the last 3 years we have treated 79 newborns with 74 survivors (94%). Their diagnoses included meconium aspiration, persistent fetal circulation, respiratory distress syndrome, congenital diaphragmatic hernia, and sepsis. Seven patients (9%) had life-threatening intrathoracic complications requiring emergent intervention while on ECMO: tension hemothorax (3), tension pneumothorax (2), and pericardial tamponade (2). Pericardial tamponade and tension hemothorax and pneumothorax show a similar pathophysiology of increasing intrapericardial pressure and decreasing venous return. Perfusion is initially maintained by the nonpulsatile flow of the ECMO circuit before further decrease in venous return results in decreasing ECMO flow and progressive hemodynamic deterioration. Each of the seven patients demonstrated a clinical triad that includes increasing PaO2 and decreasing peripheral perfusion (as evidenced by decreasing pulse pressure and decreasing SvO2) followed by decreasing ECMO flow with progressive deterioration. The diagnoses were confirmed by transillumination, chest x-ray, or cardiac echocardiogram. Initial emergent placement of a percutaneous drainage catheter was temporizing in all seven cases. However, four patients required emergent thoracotomy for definitive treatment while still on ECMO. All seven patients were weaned from ECMO and are short-term survivors (6 months to 3.5 years). As use of ECMO for newborn severe respiratory failure increases, responsible physicians must be familiar with life-threatening intrathoracic complications and appropriate treatment strategies.

Cardiac Tamponade↗
PubMed1981

Axoplasmic flow of tritiated proline in the corticospinal tract of the rat.

The rates of axoplasmic transport were studied in the corticospinal tract of the rat by injecting tritiated proline into the sensory-motor cortex and subsequently analyzing the distribution of incorporated label in the spinal cord at intervals after injection. A mathematical model of the anatomy of the corticospinal tract was developed and used in analysis of the data. The rate of a fast component was calculated to be 240-420 mm per day, which is comparable with rates of fast components in the peripheral nervous system (PNS), but considerably greater than rates in other tracts in the central nervous system. A slow component was calculated to have a transport rate of 3-8 mm per day which is greater than rates found either in the CNS or PNS. This higher rate may be related to the greater length of the corticospinal tract as compared to other CNS tracts studied.

Animals↗
PubMedDate not supplied

Efficacy of extracorporeal life support in the setting of adult cardiorespiratory failure.

The efficacy of extracorporeal life support (ECLS, ECMO) in the management of severe adult cardiorespiratory failure remains controversial. The purpose of this review is to evaluate the authors' institutional experience with ECLS in adult patients. Between 1988 and 1993, 65 moribund patients with respiratory (n = 51) and cardiac (n = 14) failure were supported with ECLS. Criteria for initiation of ECLS were: 90% chance of mortality despite maximal conventional respiratory management, good potential for recovery, and age younger than 60 years. Venovenous bypass was used in 40 and venoarterial in 25 patients. Respiratory management included low rate, low pressure ventilation with an inspired oxygen fraction < or = 0.5 and tracheostomy tube placement. Continuous systemic heparinization was used, maintaining whole blood activated clotting time (ACT) between 180 and 200 sec. Survival data are summarized as follows: pneumonia (n = 25) 56%, adult respiratory distress syndrome (n = 24) 58%, airway support (n = 2) 100%, and cardiac support (n = 14) 29%. The most common complication was bleeding (68%), which was managed in most patients by reduction of anticoagulation or local measures such as packing. Data from survivors and nonsurvivors of ECLS in patients with respiratory failure were compared in an attempt to define prognostic indicators of improved survival. The only prognostic indicator of survival that could be identified was the period of time on the ventilator before the initiation of ECLS (survivors = 3.0 +/- 2.4 days, nonsurvivors = 6.1 +/9- 4.0 days, P < 0.005). It is concluded that ECLS can be a life saving modality for the management of severe adult cardiorespiratory failure. Earlier institution of ECLS in the course of cardiopulmonary failure may improve outcome.

Adult↗