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Biomedical subjects

R W Jennings

Publications and source records attributed to R W Jennings.

At least 37 records · Page 2Linked to original sources
PubMed1998

Anterior cervical approach for repair of laryngotracheoesophageal cleft.

Laryngotracheoesophageal cleft is a very rare congenital malformation characterized by a long midline communication between the esophagus and trachea extending from the larynx down the trachea for a variable distance. The most common repair strategy involves separation of the trachea and esophagus by a lateral approach via both a thoracotomy and a neck incision. The authors report a case of complete repair (without thoracotomy) via a neck incision through the anterior wall of the trachea.

Abnormalities, Multiple↗
PubMed1998

Correction of congenital diaphragmatic hernia in utero IX: fetuses with poor prognosis (liver herniation and low lung-to-head ratio) can be saved by fetoscopic temporary tracheal occlusion.

BACKGROUND/PURPOSE: Fetuses with congenital diaphragmatic hernia (CDH) who have a "poor prognosis" with postnatal treatment now can be identified on the basis of liver herniation, early diagnosis (before 25 weeks' gestation) and a low lung-to-head ratio (LHR). Because complete in utero repair proved unsuccessful for this group, the strategy of temporary tracheal occlusion was developed to gradually enlarge the hypoplastic fetal lung. The purpose of this study is to compare the outcome of patients in the poor-prognosis group treated by one of three methods: (1) standard postnatal care, (2) fetal tracheal occlusion via open hysterotomy, and (3) the recently developed video-fetoscopic (Fetendo) technique of tracheal occlusion without hysterotomy. METHODS: In the past 3 years, 34 of 86 fetuses with an isolated left CDH met criteria for the poor-prognosis group. Thirteen families chose postnatal treatment at an extracorporeal membrane oxygenation (ECMO) center, 13 underwent open fetal tracheal occlusion, and eight underwent fetoscopic tracheal occlusion. RESULTS: The survival rate was 38% in the group treated by standard postnatal therapy, 15% in the open tracheal occlusion group, and 75% in the Fetendo group. There were less postoperative pulmonary complications noted in mothers who underwent the Fetendo procedure versus the open tracheal occlusion. All but one Fetendo clip patient had a striking physiological response demonstrated by sonographic enlargement of the small left lung that was documented postnatally by plain radiographs and its subjective appearance during repair of the CDH. In contrast, only 5 of the 13 open tracheal occlusion patients demonstrated lung growth. CONCLUSION: Fetuses with a left CDH who have liver herniation and a low LHR are at high risk of neonatal demise and appear to benefit from temporary tracheal occlusion when performed fetoscopically, but not when performed by open fetal surgery.

Adult↗
PubMed1998

Successful treatment of liver hemorrhage in the premature infant.

Intraoperative neonatal liver hemorrhage usually results in exsanguination and death. The parenchyma of a neonatal liver is fragile, and the capsule is very thin, unlike that in the pediatric and adult patient. This renders the treatment of a neonatal liver fracture almost universally unsuccessful. The current report describes two cases of successful management of intraoperative neonatal liver hemorrhage during surgery for necrotizing enterocolitis (NEC).

Enterocolitis, Pseudomembranous↗
PubMed1998

Initial studies of holmium:YAG laser creation of spinal defects in fetal rabbits: model for urologic effects of myelomeningocele.

Myelomeningocele (MMC) is characterized by paraplegia and incontinence, often necessitating surgery. Current models of MMC in sheep and primates create a spinal defect long after anomalous neural tube closure ordinarily occurs. An ideal model of MMC would allow creation of the defect at the earliest age in a low-cost species with a short gestation. We present a method utilizing the holmium laser to create spinal defects in rabbits in utero for the study of the pathophysiology and repair of MMC. Pregnant rabbits of 22 to 23 days' gestational age were prepared and draped in sterile fashion for laparotomy under general anesthesia. The abdomen was opened, and both uterine horns were inspected. Double opposing pursestring sutures were placed to secure the chorioamniotic membranes over the fetal lumbar spine. Amniotic fluid was removed with a needle and saved. Electrocautery was used to open the uterus within the pursestring suture, exposing the fetal dorsum. The spine was exposed by laser dissection of the fetal dorsal musculature. Posterior laminectomy was accomplished with laser incisions of each side of the spinous process, leaving the underlying dura and cord exposed. The pursestring was then cinched, amniotic fluid was returned, and the uterus and trocar sites were closed. Cesarian section was performed at 30 to 31 gestational days, and the pups were examined and then humanely sacrificed for histologic evaluation of the lesion. The rabbit is an inexpensive species with a short gestation (33-35 days), and four or more fetuses may be operated on per litter, with the remainder serving as controls. Utilization of minimally invasive techniques including holmium:YAG laser dissection facilitates creation of spinal defects at an early age in this small-animal model.

Animals↗
PubMed1997

Prospective analysis of lung-to-head ratio predicts survival for patients with prenatally diagnosed congenital diaphragmatic hernia.

BACKGROUND: Accurate prenatal prediction of outcome for fetuses who have congenital diaphragmatic hernia (CDH) is very difficult. The authors previously reported a retrospective analysis of risk factors for fetal CDH and proposed a new index of severity: the lung-to-head ratio (LHR). The authors now report a prospective study to test whether this new index predicts neonatal outcome. METHODS: Fifteen patients who had left-sided CDH were sonographically evaluated at the University of California, San Francisco (UCSF) and followed prenatally and postnatally. LHR was measured at 24 to 26 weeks' gestation. Outcome variables included survival and the need for extracorporeal membrane oxygenation (ECMO). RESULTS: Overall survival was 47%. LHR ranged from 0.62 to 1.86. No patient with an LHR of less than 1.0 (n = 3) survived despite ECMO, whereas all patients with an LHR greater than 1.4 survived (n = 4), one requiring ECMO. LHR values between 1.0 to 1.4 were associated with 38% survival (n = 8), 75% requiring ECMO. Overall, survivors had a mean LHR of 1.4 +/- 0.33 and nonsurvivors, 1.05 +/- 0.3 (P < .05). CONCLUSION: The LHR is a useful index to help predict neonatal outcome in patients who have left-sided CDH.

California↗
PubMed1997

The Coventry Award. The value of preoperative aspiration before total knee revision.

The value of routine aspiration of a symptomatic total knee replacement before reoperation was evaluated. The study group consisted of a consecutive series of 69 knees in 67 patients in which preoperative aspiration was performed. All aspirations were performed on an outpatient basis in a clinic setting. Local anesthetics and saline washings were not used. Twenty knees were determined to be infected and 49 knees were not infected. Preoperative aspiration had an overall sensitivity of 55%, specificity of 96%, accuracy of 84%, positive predictive value of 85%, and negative predictive value of 84%. Sixteen patients were taking antibiotics at the time of referral including 12 of 20 (60%) who had infected knees. Seven of these 12 (58%) had no growth on their initial knee aspiration. Four of these had their knees reaspirated at a later date because of a high index of suspicion for infection and the subsequent aspiration revealed the infecting organism in all four cases. Two of the remaining three patients had signs of sepsis develop and reaspiration was not performed because immediate reoperation was indicated clinically. The initial aspiration on the third patient was performed after antibiotic therapy was discontinued for 4 weeks and a repeat aspiration was not deemed necessary. When the results of the reaspirations are included, the overall aspiration results improved to a sensitivity of 75%, specificity of 96%, and accuracy of 90%. The results of the study support the use of routine preoperative aspiration before total knee revision. Previous antibiotic use increases the risk of a false negative result, and reaspiration at a later date can be expected to significantly improve the value of this test in such cases.

Aged↗
PubMed1994

Vascular changes with in utero correction of diaphragmatic hernia.

In utero surgical correction of fetal diaphragmatic hernia is a new therapeutic alternative for selected prenatally diagnosed patients. With increasing experience, the authors have found that fetuses with herniation of the liver through the diaphragmatic defect have a high incidence of perioperative death. The hypothesis was that reduction of the liver during fetal diaphragmatic hernia repair caused distortion of fetal vascular anatomy resulting in fetal demise. To study this, the authors performed angiograms through the umbilical vein in fetal and neonatal cadavers, with and without diaphragmatic hernias, and simulated in utero repair. Large fetal congenital diaphragmatic hernias can be associated with dramatic changes in the vascular anatomy of the liver. The liver does not simply rotate up into the chest through a diaphragmatic defect; instead, the liver more likely develops in the chest, with its vascular anatomy situated accordingly. Attempts to reduce a herniated liver can result in significant distortion of the fetal vasculature, leading to fetal death. Techniques to prevent vascular compromise during hepatic manipulation may improve the outcome for fetuses during in utero repair of diaphragmatic hernias.

Angiography, Digital Subtraction↗
PubMed1994

Fetal fibroblast contraction of collagen matrices in vitro: the effects of epidermal growth factor and transforming growth factor-beta.

Wound contraction is an important component of healing but, in the extreme, may lead to excessive scar formation and pathological wound contracture. Fetal rabbit wounds heal without contraction or scarring, whereas excisional fetal sheep wounds have been shown to contract, but no scarring or pathological wound contracture is noted. We used an in vitro model, the fibroblast-populated collagen lattice, to study the ability of fetal fibroblasts to coordinate contraction of a collagen matrix and the modulating effects of epidermal growth factor and transforming growth factor-beta 1 on this contraction. With increasing gestational age, fibroblasts increased the degree of collagen lattice contraction. Epidermal growth factor inhibited contraction by fetal fibroblasts, whereas transforming growth factor-beta 1 stimulated it. These findings suggest that while intrinsic differences between fetal and adult fibroblasts exist, polypeptide growth factors may operate at the site of tissue repair to alter cell phenotype. Further work is underway to delineate the role of soluble protein factors responsible for the absence of scarring and contracture seen in the fetal wound.

Animals↗
PubMed1993

Chronic fetal vascular access.

Intensive management of the fetus is limited by our inability to achieve access to the fetal circulation. Using laparoscopic surgery, we can maintain long-term access to the fetal circulation by extra-amniotic catheterisation of chorionic vessels in third-trimester monkeys and early-gestation sheep. We can sample fetal blood, continuously measure blood pressure, and infuse drugs without complications. Safe vascular access will permit assessment of fetal status during fetal surgical procedures and improve postoperative monitoring.

Animals↗
PubMed1993

Fetal neuroblastoma: prenatal diagnosis and natural history.

Obstetrical sonography has helped diagnose and define the features of some congenital malformations and tumors. We present five fetal neuroblastomas detected by routine prenatal sonography. All were adrenal tumors diagnosed between 26 and 39 weeks gestation. All 5 tumors were completely resected postnatally and the patients have remained disease free from 2 months to 10 years after resection without adjuvant therapy. A literature review collated 16 other cases of fetal neuroblastoma detected by sonography between 29 and 38 weeks gestation. These cases included 1 cervical, 1 thoracic, and 14 adrenal tumors. Thirteen neonates had Evans stage I or II tumors, and three had more advanced disease. Eleven mothers did not have hypertension or preeclampsia during the pregnancy, and the neonates all had stage I or II disease. Four mothers had hypertension or preeclampsia. Three of these neonates had stage IV or IVS disease with liver metastases, and all three had fetal hydrops. Review of the congenital neuroblastoma literature documented 71 cases diagnosed soon after birth, and several of these cases had unusual features that could have been detected by prenatal ultrasound. Four of the tumors were so large that dystocia resulted and fetal dismemberment was required for delivery. Eight of the tumors metastasized to the placenta, and 1 metastasized to the umbilical cord with subsequent fetal death. We conclude that fetal neuroblastoma can be diagnosed by prenatal sonography. Accurate staging is difficult by sonography, but in mothers with no preeclampsia symptoms the chance of widely disseminated disease is small.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The CDH two-step: a dance of necessity.

Repair of fetal diaphragmatic hernia has proven technically difficult especially when the left lobe of the fetal liver is incarcerated in the chest. A step-wise approach from both above and below the diaphragm solves several frustrating technical problems.

Fetal Diseases↗
PubMed1993

Correction of congenital diaphragmatic hernia in utero: VI. Hard-earned lessons.

Extensive experimental work suggests that repair of congenital diaphragmatic hernia (CDH) in utero may salvage severely affected fetuses who otherwise have a high expected mortality despite optimal postnatal care including extracorporeal membrane oxygenation (ECMO). We have reported that repair of CDH in utero is physiologically sound and safe for the mother, but technically difficult especially when the liver is herniated into the fetal chest. In the 3 years since our last report (1989 to 1991), 61 additional patients were referred for consideration of in utero repair. Fetal repair was attempted in 14 with severe isolated left CDH diagnosed before 24 weeks gestation. Five fetuses died intraoperatively, from technical problems related to reduction of incarcerated liver and uterine contractions--problems which have subsequently been surmounted. Nine patients were successfully repaired. Four babies survived, two delivered prematurely and died, and three died in utero within 48 hours of repair. Intraoperative technical problems have been overcome; the factors limiting successful outcome are postoperative physiologic management of the maternal-fetal unit and effective tocolysis to control preterm labor.

Fetal Death↗
PubMed1993

Radiotelemetric fetal monitoring during and after open fetal operation.

Diagnosis and treatment of fetal disease processes has advanced dramatically, but the ability to monitor the fetus in utero remains rudimentary. Open fetal operation provides a unique opportunity to correct life-threatening fetal abnormalities, but it also places the fetus at risk. Continuous intraoperative and post-operative fetal electrocardiographic monitoring may decrease the risk by optimizing fetal and maternal perioperative management. We tested an implantable radiotelemetry device that allowed continuous intraoperative and postoperative fetal electrocardiographic and temperature monitoring. The radiotelemetry device was placed subcutaneously in four fetal sheep at 100 to 112 days' gestation (term equals 145 days). During and after the fetal operation, the monitor reliably and continuously transmitted the analog fetal electrocardiogram and temperature. We then tested a similar device during human fetal operations on both an acute and a chronic basis. The radiotelemetry device permits continuous and reliable fetal monitoring during and after fetal operation and we now consider it essential to the operation. Its use should facilitate optimal fetal and maternal management and improve survival of the fetus.

Animals↗
PubMed1992

Adult-to-neonate lung transplantation: anatomic considerations.

Babies born with severe pulmonary hypoplasia are unsalvageable despite maximal therapy including extracorporeal membrane oxygenation (ECMO). Using ECMO as a bridge to transplantation, reduced-size lung grafts (pulmonary lobe or segment) could expand the pool of cadaver donors and may allow for HLA-matched living-related transplants. We tested this concept first in the piglet model and developed the technical maneuvers necessary to perform lobar and segmental lung transplants from adult pigs into neonatal piglets. Prior to clinical application, a systematic evaluation of anatomic considerations for reduced-size human lung transplantation was needed. A series of human adult and neonatal cadaver thoracic dissections were performed to determine the adult pulmonary lobe or segment with the proper size, orientation, and vascular and bronchial anatomy for use as a neonatal lung transplant. The adult right middle lobe (RML) is the best candidate for neonatal left lung replacement. The adult RML, once removed, can be rotated 180 degrees around its superior-inferior axis and the vessels and bronchus align well in the left chest of the neonate. The RML may require further reduction to fit into the neonatal left chest. Selective arterial perfusion of the RML showed the anterior segment to be a near-perfect match for fit and anatomy. This technique may eventually permit living-related lung transplantation.

Adult↗
PubMed1992

New techniques in fetal surgery.

Optimal fetal management during and after fetal surgery has been limited by an inability to reliably monitor the fetal heart rate and temperature, and by a lack of access to the fetal circulation. In order to solve these problems, we used early third trimester fetal sheep to develop: (1) an implantable radiotelemetry device that transmits the fetal electrocardiogram and temperature, and (2) an intraosseous access technique. A miniaturized radiotelemeter was implanted subcutaneously in the axilla of four fetal sheep. Safe implantation of the radiotelemeter was technically feasible and the device reliably recorded the fetal electrocardiogram and temperature both intraoperatively and postoperatively. Although many possible routes for access to the fetal circulation have been tried experimentally and clinically for both resuscitation and blood sampling, none have proven satisfactory. We assessed the use of intraosseous access in fetal sheep (n = 6) for both infusion and blood sampling. Access with an intraosseous needle was obtained in both sheep fetuses and human fetal cadavers. Blood gas values (pH, PCO2, and PO2) obtained from the medullary cavity of fetal sheep accurately reflected peripheral venous values. Resuscitation drugs reached the fetal circulation via the intraosseous route: sodium bicarbonate elevated venous bicarbonate levels from 28.4 +/- 1.7 to 31.8 +/- 2.1 mEq/dL (P < .05); injected glucose increased venous glucose levels by 520 +/- 108 mg/dL (P < .01); and injection of calcium chloride elevated venous calcium levels from 11.8 +/- 0.7 to 15.2 +/- 2.2 mEq/dL (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

A novel endoscopic transgastric fundoplication procedure for gastroesophageal reflux: an initial animal evaluation.

Complications of gastroesophageal reflux are common in adults and children. A variety of surgical procedures have been successfully used to treat this condition. All current techniques require open surgery and are associated with significant morbidity and mortality, particularly in the high risk, neurologically damaged child. The authors have developed a novel method of creating a gastric fundoplication using an endoscopic transgastric approach in pigs. The procedure involves the creation of an esophageal intussusception into the stomach under direct vision with an endoscope. The gastric fundus is then plicated around the esophagus using a custom stapling device. The transgastric approach allows creation of a fundoplication, is easily performed, is potentially effective at preventing gastroesophageal reflux, and has the obvious advantages of minimally invasive surgery over open techniques of fundoplication.

Animals↗
PubMed1992

Fetal cardiac bypass alters regional blood flows, arterial blood gases, and hemodynamics in sheep.

Successful fetal cardiac bypass might allow prenatal correction of some congenital heart defects. However, previous studies have shown that fetal cardiac bypass may result in impaired fetal gas exchange after bypass. To investigate the etiology of this impairment, we determined whether fetal cardiac bypass causes a redistribution of fetal regional blood flows and, if so, whether a vasodilator (sodium nitroprusside) can prevent this redistribution. We also determined the effects of fetal cardiac bypass with and without nitroprusside on fetal arterial blood gases and hemodynamics. Eighteen fetal sheep were studied in utero under general anesthesia. Seven fetuses underwent bypass without nitroprusside, six underwent bypass with nitroprusside, and five were no-bypass controls. Blood flows were determined using radionuclide-labeled microspheres. After bypass without nitroprusside, placental blood flow decreased by 25-60%, whereas cardiac output increased by 15-25%. Flow to all other fetal organs increased or remained unchanged. Decreased placental blood flow after bypass was accompanied by a fall in PO2 and a rise in PCO2. Nitroprusside improved placental blood flow, cardiac output, and arterial blood gases after bypass. Thus fetal cardiac bypass causes a redistribution of regional blood flow away from the placenta and toward the other fetal organs. Nitroprusside partially prevents this redistribution. Methods of improving placental blood flow in the postbypass period may prove critical to the success of fetal cardiac bypass.

Animals↗