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Biomedical subjects

Ronald B Hirschl

Publications and source records attributed to Ronald B Hirschl.

At least 55 records · Page 3Linked to original sources
PubMed2002

Vaginal reconstruction for ambiguous genitalia and congenital absence of the vagina: a 27-year experience.

BACKGROUND/PURPOSE: Gender assignment to a neonate with ambiguous genitalia is crucial. Patients with an absent vagina require the construction of an artificial vagina. In an effort to improve care, the authors have categorized their experience with this group of children. METHODS: Since 1974, we cared for 114 patients with anomalies of the genitalia. There were 53 genotypic girls with congenital adrenal hyperplasia (CAH), 16 genotypic boys with testicular feminization syndrome (TFS), 13 with mixed gonadal dysgenesis (MGD), 9 with Mayer-Rokitansky syndrome, and 4 true hermaphrodites. The remaining 19 had other genital abnormalities. RESULTS: After 1980, patients with CAH underwent clitoral recession and vaginoplasty. All patients with TFS were raised as girls and underwent orchidectomy. Eleven of the MGD patients were given a female sex assignment and underwent gonadectomy. Twenty-eight patients underwent intestinal vaginoplasty including 8 of the TFS patients, 9 with Mayer-Rokitansky syndrome, 8 patients with cloacal anomalies, 2 patients for rhabdomyosarcoma, and 1 of the MGD patients. CONCLUSIONS: (1) This review emphasizes the range of diagnoses the surgeon must be prepared to address in patients with ambiguous genitalia. (2) Colovaginoplasty is an excellent procedure for replacement of a completely absent vagina. (3) Continued evaluation of this group will delineate appropriate timing and choice of procedure.

Adolescent↗
PubMed2002

A comparison of laparoscopic and open pyloromyotomy at a teaching hospital.

BACKGROUND/PURPOSE: An increasing number of pediatric surgeons are using the laparoscopic approach to treat pyloric stenosis. The advantage of laparoscopic pyloromyotomy is uncertain and has not been evaluated in the setting of a pediatric surgery fellowship program. METHODS: The authors retrospectively reviewed the medical records of all patients who underwent pyloromyotomy for congenital hypertrophic pyloric stenosis at their institution from January 1, 1997 through December 31, 2000 (n = 117). Information obtained included age, sex, weight, admission laboratory values, attending surgeon, resident surgeon and their level of training, operating time, intraoperative and postoperative complications, time to full feedings, incidence of postoperative emesis, duration of postoperative emesis, length of stay, and total hospital charges. These variables then were compared between the open (OPEN) and laparoscopic (LAP) groups. RESULTS: From January 1, 1997 through December 31, 2000, 65 LAP and 52 OPEN pyloromyotomies were performed. Characteristics of patients in the OPEN and LAP groups were similar. The mean operating time was 33 +/- 2 minutes for OPEN versus 38 +/- 2 minutes for LAP (P =.07). The incidence of postoperative emesis (LAP, 68%, OPEN, 65%), duration of postoperative emesis (LAP, 7.3 +/- 1.2 hours; OPEN, 8.1 +/- 1.8 hours), and time to full feedings (LAP, 19.5 +/- 1.6 hours; OPEN, 19.5 +/- 1.3 hours) did not differ significantly between groups (P >.05). Mean postoperative length of stay in both groups was similar (LAP, 31 +/- 5; OPEN, 28 +/- 2 hours; P =.64). Mucosal perforation occurred in 5 patients (8%) in the Lap and 2 patients (4%) in the OPEN group (P =.39). Postoperative complications occurred in 12 LAP (18%) and 6 OPEN patients (12%, P =.31). Five LAP cases were converted to OPEN. In the LAP group there was one unrecognized mucosal perforation and one incomplete pyloromyotomy both of which required reoperation. As the laparoscopic approach was adopted, general surgery resident participation as operating surgeon in these cases decreased from 81% in 1997 to 19% in 2000. Hospital charges were higher in the LAP group, but not significantly (LAP, $6,676 +/- 1,005; OPEN, $5,292 +/- 306; P = 27). CONCLUSIONS: Laparoscopic pyloromyotomy has progressively become the dominant surgical approach to pyloromyotomy at our institution. The LAP and OPEN approaches have similar outcomes. However, the Lap approach may be associated with increased complication rates, a reduction in general surgery resident operative experience, and higher hospital charges.

Digestive System Surgical Procedures↗
PubMed2002

Fryns syndrome in children with congenital diaphragmatic hernia.

PURPOSE: Fryns syndrome is characterized by multiple congenital anomalies including Congenital Diaphragmatic Hernia (CDH), and has a reported poor prognosis with a survival rate during the neonatal period of approximately 15%. This report details the management and outcome of patients with Fryns syndrome and CDH. METHODS: Records of all liveborn patients with CDH between 1995 and 2001 in 83 hospitals were entered into the CDH database. Those with Fryns syndrome were reviewed retrospectively. RESULTS: A total of 1,833 patients were entered in the database, 23 of these had Fryns (1.3%). All patients experienced early distress requiring intubation. Ten patients (43%) were found to have other major anomalies. Seven patients underwent surgical repair at an average age of 7.5 days (range, 6 hours to 14 days). Mortality rate was 83% compared with 33% of patients with unilateral CDH (P =.01). Ten patients died within the first 24 hours. The parents of 6 patients withdrew support. Of the 4 survivors, 3 have marked developmental delay, whereas the fourth has not yet undergone formal assessment. CONCLUSIONS: The prognosis of infants with Fryns syndrome and congenital diaphragmatic hernia remains grim. Early genetic counseling and recognition of lethal anomalies may assist in determining which patients may survive.

Abnormalities, Multiple↗
PubMed2002

Partial liquid ventilation and positive end-expiratory pressure reduce ventilator-induced lung injury in an ovine model of acute respiratory failure.

OBJECTIVE: To examine the isolated and combined effects of positive end-expiratory pressure (PEEP) and partial liquid ventilation (PLV) on the development of ventilator-induced lung injury in an ovine model. DESIGN: Prospective controlled animal study. SETTING: University-based cardiovascular animal physiology laboratory. SUBJECTS: Thirty-eight anesthetized supine sheep weighing 22.3 +/- 2.2 kg. INTERVENTIONS: Animals were ventilated for 6 hrs (respiratory rate, 15; FIO2, 1.0, inspiratory/expiratory ratio, 1:1) with one of five pressure-controlled strategies, expressed as peak inspiratory pressure (PIP)/PEEP: low-PIP, 25/5 cm H2O (n = 8); high-PIP, 50/5 cm H2O (n = 8); high-PIP-PLV, 50/5 cm H2O-PLV (n = 8); high-PEEP, 50/20 cm H2O (n = 7); and high-PEEP-PLV, 50/20 cm H2O-PLV (n = 7). MEASUREMENTS AND MAIN RESULTS: Compared with the low-PIP control, high-PIP ventilation increased airleak, shunt, histologic evidence of lung injury, neutrophil infiltrates, and wet lung weight. Maintaining PEEP at 20 cm H2O or adding PLV reduced the development of physiologic shunt and dependent histologic injury indexes. Neither higher PEEP nor PLV reduced the high incidence of barotrauma observed in high-PIP animals. CONCLUSIONS: We conclude that application of PLV or PEEP at 20 cm H2O may improve gas exchange and afford lung protection from ventilator-induced lung injury during high-pressure mechanical ventilation in this model.

Acute Disease↗
PubMed2002

Increasing inspiratory time exacerbates ventilator-induced lung injury during high-pressure/high-volume mechanical ventilation.

INTRODUCTION: Ventilator-induced lung injury may be caused by overdistension of alveoli during high-pressure ventilation. In this study, we examined the effects of increasing inspiratory time on ventilator-induced lung injury. METHODS: Sprague-Dawley rats were divided into four different groups with ten animals per group. Each group was then ventilated for 30 mins with one of four ventilator strategies. All groups were ventilated with an Fio2 of 1.0 and a positive end-expiratory pressure of 0 cm H2O. Group LoP was the negative control group and was ventilated with low pressures (peak inspiratory pressure = 12 cm H2O, rate = 30, and inspiratory time = 0.5 secs). Groups iT = 0.5, iT = 1.0, and iT = 1.5 were the experimental groups and were ventilated with high pressures (peak inspiratory pressure = 45 cm H2O, rate = 10, and inspiratory times = 0.5 secs, iT = 1.0 sec, and iT = 1.5 secs, respectively). Outcome measures included lung compliance, Pao /Fio ratio, wet/dry lung weight, and dry lung/body weight. RESULTS: Final static lung compliance (p =.0002) and Pao2/Fio2 (p =.001) decreased as inspiratory time increased. Wet/dry lung weights (p <.0001) and dry lung/body weights (p <.0001) increased as inspiratory time increased. Light microscopy revealed evidence of intra-alveolar edema and hemorrhage in the iT = 1.0 and iT = 1.5 animals but not the LoP and iT = 0.5 animals. CONCLUSION: Increasing inspiratory time during high-pressure/high-volume mechanical ventilation is associated with an increase in variables of lung injury.

Animals↗
PubMed2002

Support of respiratory failure in the pediatric surgical patient.

Severe respiratory failure in newborn and pediatric patients is associated with significant morbidity and mortality. Basic science laboratory investigation has led to advances in the understanding of ventilator-induced lung injury and in optimizing the supportive use of conventional ventilation strategies. Over the past few years, progress has been made in alternative therapies for supporting children and adults with severe respiratory failure. This review will focus on recent laboratory and clinical data regarding the techniques of lung protective ventilator strategies, inhaled nitric oxide, liquid ventilation, and extracorporeal life support (ECLS, ECMO). Some of these modalities are commonplace, while others may have much to offer the pediatric clinician if their benefit is clearly demonstrated in future clinical trials.

Adolescent↗
PubMed2002

Gastric transposition for esophageal replacement in children: experience with 41 consecutive cases with special emphasis on esophageal atresia.

OBJECTIVE: To evaluate the authors' experience with gastric transposition as a method of esophageal replacement in children with congenital or acquired abnormalities of the esophagus. SUMMARY BACKGROUND DATA: Esophageal replacement in children is almost always done for benign disease and thus requires a conduit that will last more than 70 years. The organ most commonly used in the past has been colon; however, most series have been fraught with major complications and conduit loss. For these reasons, in 1985 the authors switched from using colon interpositions to gastric transpositions for esophageal replacement in infants and children. METHODS: The authors retrospectively reviewed the records of 41 patients with the diagnoses of esophageal atresia (n = 26), corrosive injury (n = 8), leiomyomatosis (n = 5), and refractory gastroesophageal reflux (n = 2) who underwent gastric transposition for esophageal replacement. RESULTS: Mean +/- SE age at the time of gastric transposition was 3.3 +/- 0.6 years. All but two transpositions were performed through the posterior mediastinum without mortality or loss of the gastric conduit despite previous surgery on the gastric fundus in 8 (20%), previous esophageal operations in 15 (37%), and previous esophageal perforations in 6 (15%) patients. Complications included esophagogastric anastomotic leak (n = 15, 36%), which uniformly resolved without intervention; stricture formation (n = 20, 49%), all of which no longer require dilation; and feeding intolerance necessitating jejunal feeding (n = 8, 20%) due to delayed gastric emptying (n = 3), feeding aversion related to the underlying anomaly (n = 1), or severe neurological impairment (n = 4). No redo anastomoses were required. CONCLUSIONS: Gastric transposition reestablishes effective gastrointestinal continuity with few complications. Oral feeding and appropriate weight gain are achieved in most children. Therefore, gastric transposition is an appropriate alternative for esophageal replacement in infants and children.

Adolescent↗
PubMed2002

Effects of partial liquid ventilation on unilateral lung injury in dogs.

STUDY OBJECTIVE: The overall physiologic effect of partial liquid ventilation (PLV) in the setting of unilateral lung injury remains unclear. Therefore, we evaluated the effect of PLV on gas exchange in unilateral lung injury. DESIGN AND METHODS: Left unilateral lung injury was induced in 14 adult dogs by oleic acid instillation into a left pulmonary artery. The animals were divided into two groups: gas ventilation (GV) and PLV. During both GV and PLV, systemic blood gas levels were analyzed. Oxygen consumption (O(2)), carbon dioxide production (CO(2)) and pulmonary blood flow (Q) of both the right lung (uninjured lung) and left lung (injured lung) were measured. RESULTS: During PLV, O(2) of the injured left lung (o(2)-injured), CO(2) of the injured left lung (CO(2)-injured), and Q of the injured left lung (Q-injured) were greater than those in GV (O(2)-injured, 41.6 mL/min vs 23.4 mL/min, p = 0.006; CO(2)-injured, 34.4 mL/min vs 25.5 mL/min, p = 0.026; and Q-injured, 0.47 L/min vs 0.22 L/min, p = 0.002, respectively). However, overall PaO(2) during PLV was less than that during GV, likely due to either a redistribution of Q toward the injured lung (PLV Q-injured, 0.47 L/min vs GV Q-injured, 0.22 L/min; p = 0.002) or reduced gas exchange efficiency in the healthy lung. CONCLUSIONS: We conclude that in our model, PLV increases O(2) and VCO(2) in the injured lung. However, over all gas exchange efficiency is reduced.

Animals↗
PubMedDate not supplied

Perfusion induced hyperthermia for oncologic therapy with cardiac and cerebral protection.

Cancer can be preferentially damaged and killed at temperatures above 41.0 degrees C. However, the heart and brain malfunction at this temperature, limiting the application of systemic hyperthermia in the treatment of metastatic cancer. We created a hyperthermic perfusion system that maximizes the temperature differential produced and extends the safe hyperthermic time. Mongrel dogs were anesthetized and mechanically ventilated. Temperature probes were placed in the rectum, bladder, peritoneal cavity, proximal aorta, pulmonary artery, and right tympanic canal. Venoarterial perfusion was instituted and the perfusate was warmed to 44 to 45 degrees C. The dogs' rectal temperature was elevated to > or = 42 degrees C for 4 hours. A small amount of venous blood was cooled to 28 to 30 degrees C and reperfused into the right atrium to maintain the pulmonary artery temperature < or = 38 degrees C. At the end of the perfusion, the dogs were decannulated, recovered, and returned to their cages for observation. Ten of 11 dogs survived the operative procedure, and no neurologic deficits were observed. The rectal temperature was successfully elevated to > or = 42 degrees C for 4 hours while maintaining the heart and brain at < or = 38 degrees C. Moderate serum biochemical changes were observed postprocedure. However, only the aspartate transaminase and alkaline phosphatase levels remained elevated above both the baseline and canine reference values by day 7. Lower abdominal and pelvic hyperthermia at 42 degrees C can be safely produced and maintained for 4 hours using an extracorporeal perfusion circuit, while protecting the heart and brain from temperature elevation.

Animals↗
PubMedDate not supplied

A review of 100 patients transported on extracorporeal life support.

Between May 1990 and January 1999, 100 patients (68 adult, 32 pediatric) with severe respiratory or cardiac instability were successfully transported to the University of Michigan Medical Center on extracorporeal life support. Diagnoses included adult respiratory distress syndrome (n = 78), cardiac failure (n = 7), sepsis (n = 7), asthma (n = 5), respiratory distress syndrome (of newborn) (n = 2), and airway compromise (n = 1). Of the patients, 53 were supported with venovenous bypass and 47 with venoarterial bypass. Patients were transported by ground ambulance (n = 80), helicopter (n = 15), or fixed-wing aircraft (n = 5). The median transport distance was 44 miles (range 2-790 miles), and the median transport time was 5 hours and 30 minutes (range: 1 h 33 min to 16 h 6 min). Sixty-six patients (66%) survived to discharge. One death occurred during cannulation, and two patients died before cannulation began. Complications that occurred during transport included 10 cases of electrical failure, 3 cases of circuit tubing leakage, and 1 case each of circuit rupture, membrane lung thrombosis, and membrane lung leakage. None of the complications occurring during transport had an adverse effect on outcome. We conclude that the long distance transport of patients on extracorporeal life support can be safely accomplished and is an effective option for the unstable patient with severe respiratory or cardiac failure.

Adult↗
PubMedDate not supplied

Design of an artificial lung compliance chamber for pulmonary replacement.

Matching the impedance of an artificial lung for pulmonary replacement to native pulmonary impedance is important in preventing right ventricular dysfunction. A lumped-parameter theoretical model and bench-top experiments were used to investigate the effect of a prototype compliance chamber on input impedance. The bench-top simulation consisted of a pulsatile flow generator, a prototype compliance chamber, and a low resistance artificial lung connected in series. Effective compliance was varied using pneumatic compression. The theoretical model considered a similar circuit with resistors before and after a compliance element. The bundle flow pulsatility (flow amplitude divided by average flow) and input impedance were calculated in the theoretical and experimental models. More compliance and lower upstream resistance result in lower bundle flow pulsatility and reduced first harmonic impedance. Matching the time scale of the circuit to the period of pulsatile flow also reduces impedance. The bench-top circuit demonstrated an optimal chamber pressure at which first harmonic impedance is reduced by 80%. The prototype compliance chamber in series with the artificial lung more closely matches native pulmonary impedance. The lumped-parameter model and the bench-top simulation will aid in the design and testing of compliance chamber modifications to improve its efficiency.

Artificial Organs↗
PubMedDate not supplied

Comparison of static airway pressures during total liquid ventilation while applying different expiratory modes and time patterns.

To compare pump driven (active) and gravity-siphon (passive) expiration modes during perfluorocarbon total liquid ventilation (TLV), a liquid ventilator was developed capable of providing either expiration mode. In a prospective, controlled laboratory study, 90 rabbits (3.2 +/- 0.1 kg) were anesthetized, tracheotomized, killed. After prefill with 12 ml/kg perflubron and TLV for 90 minutes (tidal volume 12 ml/kg, I:E ratio 1:2), randomly using passive (height 40 or 80 cm) or active expiration, respiratory rates were 4, 8, or 12/min. Static peak inspiratory and end-expiratory intratracheal pressures were measured at 5 minute intervals. Peak inspiratory and end-expiratory were constant in active groups, and increases in all 40 cm and 80 cm passive groups were significant. Differences between groups were significant for expiratory mode but not for respiratory rates. Only passive groups showed significant increases in body weight after TLV. Percentage of fluorothoraces was 10% using active and 85% using passive expiration. Based upon the stability of intrapulmonary pressures and volumes and a reduced rate of fluorothoraces, active expiration is more efficient than passive drainage during TLV.

Animals↗
PubMedDate not supplied

Total liquid ventilation: dynamic airway pressure and the development of expiratory flow limitation.

Expiratory flow limitation occurs during total liquid ventilation (TLV), and is characterized by the sudden development of excessively negative intratracheal pressures without increases in flow. The purpose of this study was to identify a dynamic signal for the servoregulation of expiratory flow (Ve), by determining the range of dynamic intratracheal pressures [P(T)], which mark the onset of flow limitation during liquid expiration, where choke occurs at the critical pressure (Pc). The lungs of rabbits were filled with perflurocarbon to an end-inspiratory lung volume (EILV) of 20, 30, or 40cc/kg and connected to a piston driven liquid ventilator, which removed perfluorocarbon at a rate (Vs) of 2.5, 5.0, or 7.5 ml/s. Nine animals per EILV group were used (27 animals total), and within each EILV group each (Vs) was used three times. P(T) and (Ve) (T) were measured at the tracheostomy tube, and dP/dT was calculated from P(T). Pc was determined within each EILV/(Vs) group by examining the average dP/dT curve for the first significant change from baseline. Pc ranged from -6.02 +/- 1.83 to -9.02 +/- 3.2 mm Hg. In general, the higher the EILV, the more negative the Pc. We conclude that Pc during TLV varies within a limited range in rabbits. These data may be used to maximize expired volume during TLV by sequentially tapering flow rates as this critical range of pressures is approached.

Animals↗
PubMedDate not supplied

Location of flow limitation in liquid-filled rabbit lungs.

The effects of end-inspiratory lung volume (EILV) and expiratory flow rate (Q) on the location of flow limitation in liquid-filled lungs were investigated by measuring pressure along the airways and by radiographic imaging. The lungs of New Zealand white rabbits were filled with perfluorocarbon to the randomly selected EILV of 20, 30, or 40 ml/kg, and the volume was actively drained at one of three Q: 2.5, 5.0, or 7.5 ml/s. The minimum pressures recorded by a movable catheter at locations along the airways show that flow limitation occurred in the main bronchi and trachea, and was independent of EILV and Q. The minimum pressure at the trachea was -80 mm Hg compared with values that were more positive than -10 mm Hg at a location 3 cm distal to the carina for all EILV and Q combinations. This location was confirmed by the lung images. The airway diameters gradually decreased with time, until flow limitation occurred. In airways distal to the collapse, there was not a significant decrease in diameter. Based on these data, we conclude that flow limitation in liquid-filled lungs occurs in the trachea and main bronchi and its location is independent of EILV or Q.

Animals↗
PubMedDate not supplied

In vitro fluid mechanical effects of thoracic artificial lung compliance.

This in vitro study sought to determine what compliance minimizes thoracic artificial lung impedance and pump power output. A pulsatile pump drove 3.0 cP glycerol through a circuit consisting of an MC3 Biolung preceded by a piston-cylinder (PC, n = 5) chamber with a variable compliance or a polyurethane (n = 4) chamber with a fixed, yet pressure-dependent, compliance. Each chamber was tested at flow rates of 1.8, 3.0, and 5.0 l/min and heart rates of 60, 75, and 100 bpm. Compliances, C, from 0-20 ml/mm Hg were tested in the PC chamber. Instantaneous pump outlet flow and pressure were acquired for determination of device zeroth and first harmonic input impedance, Z(0) and Z(1), and pump steady and pulsatile output powers, P(s) and P(p). PC chamber results indicate that Z(0), Z(1), P(s), and Pp were minimized at C > 1, 5, 0.5, and 4 ml/mm Hg, respectively. This suggests that C should be 1 ml/mm Hg at minimum and ideally 5 ml/mm Hg. The polyurethane chamber was statistically similar to the PC chamber at C = 1 ml/mm Hg when comparing Z(0) and P(s), but was statistically inferior when comparing Z(1) and P(p). The polyurethane compliance chamber, therefore, should be redesigned with greater compliance.

Artificial Organs↗
PubMedDate not supplied

Expiratory flow limitation during gravitational drainage of perfluorocarbons from liquid-filled lungs.

Flow limitation during pressure-driven expiration in liquid-filled lungs was examined in intact, euthanized New Zealand white rabbits. The aim of this study was to further characterize expiratory flow limitation during gravitational drainage of perfluorocarbon liquids from the lungs, and to study the effect of perfluorocarbon type and negative mouth pressure on this phenomenon. Four different perfluorocarbons (PP4, perfluorodecalin, perfluoro-octyl-bromide, and FC-77) were used to examine the effects of density and kinematic viscosity on volume recovered and maximum expiratory flow. It was demonstrated that flow limitation occurs during gravitational drainage when the airway pressure is < or = -15 cm H(2)O, and that this critical value of pressure did not depend on mouth pressure or perfluorocarbon type. The perfluorocarbon properties affect the volume recovered, maximum expiratory flow, and the time to drain, with the most viscous perfluorocarbon (perfluorodecalin) taking the longest time to drain and resulting in lowest maximum expiratory flow. Perfluoro-octyl-bromide resulted in the highest recovered volume. The findings of this study are relevant to the selection of perfluorocarbons to reduce the occurrence of flow limitation and provide adequate minute ventilation during total liquid ventilation.

Animals↗
PubMedDate not supplied

Effect of artificial lung compliance on right ventricular load.

Artificial lungs may serve as transplant alternatives to patients with respiratory failure. To provide a pulmonary replacement, the device cannot significantly alter right ventricular afterload. We sought to characterize cardiac load using a prototype artificial lung as a pulmonary replacement. An artificial lung was implanted into 13 adult sheep, 7 using a noncompliant original prototype and 6 using a modified device with a compliance chamber. Inflow was from the pulmonary artery and outflow into the left atrium. Pulmonary impedance was determined and pulse wave reflections analyzed. Resistance was similar in the original prototype artificial lung and in the native pulmonary circulation (3.0 vs 3.2 Woods units, p = 0.5). First harmonic impedance was significantly increased in the original prototype artificial lung (0.4 vs 5.9 Woods units, p < 0.01). High-amplitude pulse wave reflections were identified and right ventricular function was altered. The addition of compliance to the artificial lung reduced impedance at the first harmonic (5.9 vs 1.9 Woods units, p < 0.01), decreased the amplitude of pulse wave reflections, and normalized right ventricular function. A low-resistance but noncompliant artificial lung increases pulmonary impedance and alters right ventricular function. Addition of a compliance chamber reduces pulse wave reflections and normalizes ventricular function.

Animals↗