Effects of mine strata thermal behavior and mine initial temperatures on mobile refuge alternative temperature.

Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines. Mobile RAs have a limited ability to dissipate heat, and heat buildup can lead to a life-threatening condition as the RA internal air temperature and relative humidity increase. The U.S. National Institute for Occupational Safety and Health (NIOSH) performed heat testing on a 10-person tent-type training RA and contracted ThermoAnalytics Inc. to develop a validated thermal simulation model of the tested RA. The model was used to examine the effects of the constant mine strata temperature assumption, initial mine air temperature, initial mine strata surface temperature (MSST), initial mine strata temperature at depth (MSTD) and mine strata thermal behavior on RA internal air temperature using 117 W (400 Btu/h) of sensible heat input per simulated miner. For the studied RA, when the mine strata temperature was treated as a constant, the final predicted RA internal air temperature was 7.1°C (12.8°F) lower than it was when the mine strata thermal behavior was included in the model. A 5.6°C (10.0°F) increase in the initial MSST resulted in a 3.9°C (7.1°F) increase in the final RA internal air temperature, whereas a 5.6°C (10°F) increase in the initial MSTD yielded a 1.4°C (2.5°F) increase in the final RA internal air temperature. The results indicate that mine strata temperature increases and mine strata initial temperatures must be accounted for in the physical testing or thermal simulations of RAs.

Analysis of heat loss mechanisms for mobile tent-type refuge alternatives.

Federal regulations require that refuge alternatives (RAs) be located within 305 m (1,000 ft) of the working face and spaced at one-hour travel distances in the outby area in underground coal mines, in the event that miners cannot escape during a disaster. The Mine Safety and Health Administration mandates that RAs provide safe shelter and livable conditions for a minimum of 96 hours while maintaining the apparent temperature below 35 °C (95 °F). The U.S. National Institute for Occupational Safety and Health used a validated thermal simulation model to examine the mechanisms of heat loss from an RA to the ambient mine and the effect of mine strata composition on the final internal dry bulb temperature (DBT) for a mobile tent-type RA. The results of these studies show that 51 percent of the heat loss from the RA to the ambient mine is due to radiation and 31 percent to conduction. Three mine width and height configurations and four mine strata compositions were examined. The final DBT inside the RA after 96 hours varied by less than 1 °C (1.8 °F) for the three mine width/height configurations and by less than 2 °C (3.6 °F) for the four mine strata compositions.

Echocardiographic measures of ventricular function and pulmonary artery size: prognostic markers of congenital diaphragmatic hernia?

OBJECTIVE: To compare echocardiographic measures of biventricular function and pulmonary artery size in infants with congenital diaphragmatic hernia (CDH) and normal controls, and examine their correlation, if any, with outcomes in CDH. STUDY DESIGN: We included consecutive neonates (<1 month old) with CDH and term controls without structural heart defects. Clinical and outcomes data were recorded and echocardiograms evaluated for right ventricular (RV) and left ventricular (LV) myocardial performance index (MPI), cardiac output index (CI) and McGoon index, among others. Statistical analyses (SPSS version 17, SPSS, Chicago, IL, USA) included between-group comparisons, using analysis of variance and χ(2)-test and binary regression, with significance set at P<0.05. RESULT: Infants with CDH (n=34) were comparable with controls (n=35) in their age, weight, gestational age and gender. CDH was left sided in 24 (70%) neonates. Extracorporeal membrane oxygenation (ECMO) was required in 15 (45%) neonates; 18 (53%) infants survived. MPIs, CI and eccentricity index in systole were significantly worse in the CDH group, compared with controls and among CDH infants who died, compared with survivors. Infants with CDH who died or needed ECMO had significantly impaired MPIs and CI than survivors. On regression analyses, LV CI and MPIs were independently associated with mortality. CONCLUSION: Infants with CDH had significantly impaired ventricular function and pulmonary hypertension, compared with controls. In the CDH group, LV dysfunction was associated with death and adverse outcomes. Further studies incorporating echocardiographic indices as prognostic markers of CDH are warranted.

Factors affecting the outcome in patients with gastroschisis: how important is immediate repair?

BACKGROUND: Since 30 years, we have attempted to repair gastroschisis as early as possible, often even in the delivery room. We examined 12 recent years of patient records to evaluate the effect of immediate repair and other factors on the outcome of gastroschisis. METHODS: We reviewed the medical records of patients presenting with gastroschisis (87) at the Children's Hospital of Michigan between 1998 and 2009. Data were evaluated specifically to determine the effect of the place of repair [obstetric hospital ("DR") vs. children's hospital ("OR")], the time of repair [less than an hour after delivery ("IR") or more than one hour ("ER")], and the type of repair [primary fascial repair and skin closure ("PR") vs. staged repair ("SR")]. RESULTS: Patients in the PR group were more likely to spend one week or less on MV (66% in PR vs. 11% in SR, p<0.01). Patients in the DR group were more likely to spend 2 weeks or less on TPN, as were patients in the PR group (51% in PR vs. 17% in SR, p<0.01). Patients in the PR group were more likely to stay in hospital for less than 3 weeks, but the IR and ER groups had almost same hospital stay. Major associated anomalies were present in 19 patients (29%). These patients and those with little or no peel tended to outperform those with peel in each of our outcome measures. CONCLUSION: Repair immediately after delivery is beneficial in terms of achieving primary closure of the defect, leading to shorter times on assisted ventilation and parenteral nutrition, and shorter hospital stays.

Access to the hypertrophic pylorus: does it make a difference to the patient?

BACKGROUND: The aim of the study was to evaluate the effects of different access methods for the treatment of pyloric stenosis (PS). METHODS: Since 2001, we have operated on children with PS using three different access methods: classic right upper quadrant transverse incision (TI), incision on the superior umbilical fold (UI) and laparoscopic (L). We reviewed the records of these children with special emphasis on the number and characteristics of complications, operative time, and length of stay (LOS). RESULTS: We identified 256 patients (212 M, 44 F) with a mean age of 36 days. 138 procedures were performed using TI, 18 with UI and 100 laparoscopically. The mean operative time for patients with TI was 35.9 +/- 8.6 min, and for those with UI 31.8 +/- 9.3 min. Patients in the L group had a mean operative time of 29.8 +/- 11 min. Although the operative time for TI was significantly greater than that of L, the differences between the TI and UI groups and between UI and L groups did not reach statistical significance. For the TI, UI and L groups, the mean overall LOS was 3.22 +/- 0.3 days, 3.39 +/- 0.4 days and 2.94 +/- 0.2 days, and the mean postoperative LOS was 1.52 +/- 0.1 days, 1.44 +/- 0.2 days, and 1.56 +/- 0.1 days, respectively. No significant difference in LOS was found. One patient from each group had a wound infection. While three of four perforations occurred in the L group and the fourth was in the TI group, the difference in rates of perforation among the groups did not achieve statistical significance. The perforation during open surgery was typical, occurring on the duodenal end during spreading of the pyloric muscle. The perforations in the L group were atypical: one was a grasper injury to the duodenum; another was on the gastric end of the pyloric incision and the third occurred not during spreading of the pyloric muscle but during the cutting of it. The pylorus was relatively small in this particular case (12 mm in length). CONCLUSION: While the operative time of laparoscopic repair for PS is less than in either of the open approaches, laparoscopic surgery may increase the risk for atypical injuries to the bowel. Therefore, proper attention should be paid to dissection of the structures and the selection of laparoscopic instruments. Incision on the superior umbilical fold is a reasonable alternative access for the treatment of PS.

A prototype biosensor-integrated image-guided surgery system.

BACKGROUND: In this study we investigated the integration of a Raman spectroscopy-based biosensor with an image-guided surgery system. Such a system would provide a surgeon with both a diagnosis of the tissue being analysed (e.g. cancer) and localization information displayed within an imaging modality of choice. This type of mutual and registered information could lead to faster diagnoses and enable more accurate tissue resections. METHODS: A test bed consisting of a portable Raman probe attached to a passively articulated mechanical arm was used to scan and classify objects within a phantom skull. RESULTS: The prototype system was successfully able to track the Raman probe, classify objects within the phantom skull, and display the classifications on medical imaging data within a virtual reality environment. CONCLUSION: We discuss the implementation of the integrated system, its accuracy and improvements to the system that will enhance its usefulness and further the field of sensor-based computer-assisted surgery.

[Evaluation of different breathing and contrast-protocols concerning quality and alignment in 18F-FDG PET/CT]. / Vergleich verschiedener Atem- und Kontrastmittelprotokolle bezüglich Bild- und Koregistrierungsqualität bei 18F-FDG-PET/CT-Untersuchungen.

PURPOSE: The purpose of this study was to establish a reliable and simple parameter for alignment evaluation and the evaluation and optimization of state-of-the-art contrast-enhanced examination protocols for (18)F FDG-PET/CT. MATERIALS AND METHODS: 44 consecutive patients were referred to 4 examination protocols. Group A and B underwent single-phase, contrast-enhanced CT (90 s delay) performed either during free shallow breathing (FA; group A) or normal expiration (NormExp; group B). Groups C and D underwent arterial and portal venous multiphase examinations performed during FA (group C) or during NormExp (group D) followed by a low-dose CT scan for attenuation correction. Organ displacement in the cranio-caudal direction was correlated with a 3D-vectorial shift. For alignment evaluation discrepancies with respect to size and liver location, the spleen and kidneys were calculated. Additionally, the groups were compared with regard to the presence of CT artifacts. RESULTS: Cranio-caudal organ shift and 3D-vectorial shift showed a high correlation (r > 0.8). Single-phase CT scans performed during NormExp yielded better image quality (p < 0.001) and alignment (p < 0.01 for liver, spleen and right kidney) than those performed during FA. Differences in organ size did not differ during FA and NormExp. Depending on the evaluated organ, breathing and contrast protocol misalignment was in the cranio-caudal direction 0-27 mm (mean: 6.8; standard deviation: +/- 4.9) in multiphase CT compared to 0 - 11 mm (mean: 4.5 +/- 2.3) in single-phase examinations. CONCLUSION: 1. Organ shift in the cranio-caudal direction is a good and simple parameter for alignment evaluation. 2. Alignment and CT quality are best in expiration protocols. 3. Despite comparatively low alignment quality, integrated multiphase CT examinations show acceptable quality and alignment.

Robot-assisted minimally invasive Kasai portoenterostomy: a survival porcine study.

BACKGROUND: Major enhancements offered by robotic surgery for minimally invasive procedure include tremor filtration, motion scaling, and the addition of a wrist to the instrument. Minor enhancements include indexing as well as safe and rapid instrument exchange. A benefit associated with any endoscopic procedure is magnification. It was hypothesized that these enhancements would allow the performance of complex gastrointestinal surgery. METHODS: Eight survival pigs (weight, 2.5-8 kg) underwent a robotically assisted minimally invasive portoenterostomy. The procedure was analogous to the Kasai portoenterostomy for biliary atresia usually performed for human patients at the age of 4 to 12 weeks. RESULTS: Five of the eight animals survived for more than 1 month after the operation, returning to normal eating and bowel habits in 2 to 3 days. None were jaundiced. All laboratory values were normal. At 1 month, the animals were killed. There was no anastomotic stenosis at either the end-to-side enteroenterostomy or the portoenterostomy. Histologically, the anastomoses were well healed. CONCLUSION: Computer-assisted robot-enhanced technology allows complex gastrointestinal surgery to be performed using minimally invasive techniques.

Three quantitative approaches to the diagnosis of abdominal pain in children: practical applications of decision theory.

BACKGROUND/PURPOSE: The authors compared 3 quantitative methods for assisting clinicians in the differential diagnosis of abdominal pain in children, where the most common important endpoint is whether the patient has appendicitis. Pretest probability in different age and sex groups were determined to perform Bayesian analysis, binary logistic regression was used to determine which variables were statistically significantly likely to contribute to a diagnosis, and recursive partitioning was used to build decision trees with quantitative endpoints. METHODS: The records of all children (1,208) seen at a large urban emergency department (ED) with a chief complaint of abdominal pain were immediately reviewed retrospectively (24 to 72 hours after the encounter). Attempts were made to contact all the patients' families to determine an accurate final diagnosis. A total of 1,008 (83%) families were contacted. Data were analyzed by calculation of the posttest probability, recursive partitioning, and binary logistic regression. RESULTS: In all groups the most common diagnosis was abdominal pain (ICD-9 Code 789). After this, however, the order of the most common final diagnoses for abdominal pain varied significantly. The entire group had a pretest probability of appendicitis of 0.06. This varied with age and sex from 0.02 in boys 2 to 5 years old to 0.16 in boys older than 12 years. In boys age 5 to 12, recursive partitioning and binary logistic regression agreed on guarding and anorexia as important variables. Guarding and tenderness were important in girls age 5 to 12. In boys age greater than 12, both agreed on guarding and anorexia. Using sensitivities and specificities from the literature, computed tomography improved the posttest probability for the group from.06 to.33; ultrasound improved it from.06 to.48; and barium enema improved it from.06 to.58. CONCLUSIONS: Knowing the pretest probabilities in a specific population allows the physician to evaluate the likely diagnoses first. Other quantitative methods can help judge how much importance a certain criterion should have in the decision making and how much a particular test is likely to influence the probability of a correct diagnosis. It now should be possible to make these sophisticated quantitative methods readily available to clinicians via the computer.

Neurodevelopmental outcome after congenital diaphragmatic hernia: Extracorporeal membrane oxygenation before and after surgery.

BACKGROUND/PURPOSE: Extracorporeal membrane oxygenation (ECMO) as a treatment of last resort for neonates with persistent pulmonary hypertension of the newborn (PPHN) caused by congenital diaphragmatic hernia (CDH) may be used for preoperative stabilization or postoperative rescue. The aim of this study was to examine the acute and long-term morbidity associated with pre- and postoperative ECMO. METHODS: Neonates born with CDH and needing ECMO were classified into 2 groups. Group 1 consisted of neonates placed on ECMO after CDH surgery. Patients in group 2 underwent preoperative ECMO stabilization. Medical records after birth were evaluated. Growth, neuromotor and cognitive development, hearing, and behavior were evaluated. Student t test and chi(2) were used to determine statistical significance between groups. RESULTS: Subjects in group 2 had significantly more days on ECMO and loop diuretics. Alkalosis was induced for a longer duration in group 2. At follow-up 3 to 9 years later, no differences were found between the 2 groups in growth parameters, neuromotor outcome, or behavior. However, in group 1, 2 of 9 children had significant hearing impairment necessitating amplification compared with 6 of 6 subjects in group 2. CONCLUSIONS: Neonates with CDH first stabilized on ECMO (group 2) had a higher incidence of hearing loss compared with those needing ECMO postrepair (group 1). The etiology of this finding is not clear. This may be secondary to the prolonged period of hyperventilation or general intensive care that is part of the protocol for neonates who are electively stabilized on ECMO preoperatively. J Pediatr Surg 36:539-544.

Factors associated with the resolution of postoperative ileus in newborn infants.

Reliable indicators of ileus resolution following laparotomy have not been identified in newborn infants. The purpose of this study was to correlate commonly available clinical parameters with the resolution of postoperative ileus in newborn infants after abdominal procedures. The presentation, treatment, and postoperative abdominal examination of 60 consecutive newborn infants who underwent a heterogeneous group of primary abdominal operations were evaluated. No significant association was observed between the time to first bowel movement (resolution of ileus) and age, postconceptual age, weight, degree of intraabdominal contamination, duration of surgery, type of operative procedure, presence or absence of abdominal distension, and time to first bowel sounds. Opioid use was associated with a delay in the time to first bowel movement that was not accounted for by the effects of any other variable. Easily obtainable clinical parameters are not universally useful for predicting the duration of ileus in newborn infants after abdominal surgery. The use of opioids is associated with delayed resolution of ileus. Measures to limit the use of opioids may be effective in shortening the duration of postoperative ileus in newborn infants.

Bile duct size does not predict success of portoenterostomy for biliary atresia.

BACKGROUND/PURPOSE: Presence of large bile ducts (>200 microm) at the portal end-plate has been suggested to predict success after portoenterostomy. The authors reviewed their patients with biliary atresia to test the hypothesis that bile duct size in patients with successful portoenterostomy was no different than in the patients with unsuccessful portoenterostomy. METHODS: The authors reviewed the patients at their institution from 1989 to 1998 who had the diagnosis of biliary atresia (n = 38). A pathologist blinded to the results of the operation confirmed the measurements of the bile duct remnants. RESULTS: Five of the 38 patients did not have a portoenterostomy. They underwent cholangiogram and liver biopsy and were evaluated for liver transplantation. All patients who underwent surgery (n = 33) had a Roux-en-y hepaticojejunostomy. Twenty-one patients had successful surgery (64%) and 12 patients (36%) had unsuccessful surgery. The average age at operation in the successful group was 50.9 +/- 3 days and in failures, 57.9 +/- 4 days (P = .16). Duct size at the portal end-plate was not different between the successes and failures. Two of the patients in the success group had no evidence of bile ducts grossly or histologically. CONCLUSION: Children presenting early in infancy (<3 months) with biliary atresia should undergo a portoenterostomy regardless of the size of the bile ducts at the time of exploration.

Cardiac tamponade caused by serous pericardial effusion in patients on extracorporeal membrane oxygenation.

PURPOSE: Extracorporeal membrane oxygenation (ECMO) has been successful in the treatment of critically ill children; however, its use has been accompanied by a broad range of complications. The authors describe the presentation, clinical course, treatment, and outcome of 4 patients on ECMO in whom pericardial tamponade developed caused by a serous effusion. METHODS: A retrospective review of patients placed on ECMO at our institution from 1993 to 1997 was performed. The case histories of 4 patients in whom pericardial tamponade developed caused by a serous effusion were reviewed in detail. RESULTS: The first patient presented with hypotension while on venovenous (VV) ECMO. The hypotension improved with fluid resuscitation. The patient was converted from (VV) to venoarterial (VA) ECMO when hypotension recurred. After a third episode of hypotension, a narrow pulse pressure was noted, and echocardiography results confirmed a pericardial effusion. The diagnosis was recognized earlier in the course of the subsequent 3 patients. All 4 patients were treated with aspiration of serous fluid from the pericardium with an over-the-needle plastic catheter that was left in place. More than 1 aspiration was required in all cases. All 4 patients survived. CONCLUSIONS: The authors have identified a group of ECMO patients with pericardial tamponade caused by serous effusion with good response to treatment. A high index of suspicion and early echocardiography is warranted to confirm the diagnosis in a patient with hypotension on ECMO.

Muscle and nerve biopsy in the evaluation of neuromuscular disorders: the surgeon's perspective.

BACKGROUND/PURPOSE: A muscle biopsy frequently is requested by the neurologist evaluating a child with neuromuscular symptoms. However, there are no reports discussing the preoperative evaluation for, and diagnostic yield of, this procedure. The authors reviewed our experience over a 10-year period to obtain these data. METHODS: The records of 153 patients who underwent muscle biopsy were reviewed with particular attention to the cardiology evaluation, the pathology report, and any resultant change in diagnosis and treatment of the child. RESULTS: All 153 specimens contained adequate tissue for complete histological analysis. Preoperative cardiology consults were obtained in 82% of the children, with abnormalities found in 9%. Severe cardiac dysfunction was found in three children, all of whom had a previously diagnosed cardiomyopathy or dysrhythmia. No pathological abnormality was found in 41% of the muscle biopsy specimens, and nonspecific pathological findings were described in 23%. A specific diagnosis was made in 36%. Only 19% of the children had their treatment changed by the results of the muscle biopsy. CONCLUSIONS: Muscle biopsies can be performed safely without routine preoperative cardiac evaluation. A specific diagnosis, however, may be made in less than half of the patients with a change in therapy available for even fewer.

Rapid hepatocyte spheroid formation: optimization and long-term function in perfused microcapsules.

Enhancement of cell-cell interactions and, hence, long-term function in liver support systems can be effected by controlling the diameters of hepatocyte aggregates or spheroids. In this study, primary rat hepatocytes were induced to rapidly form spheroids using an intermittent settling and agitation protocol. The cells were seeded into albumin coated flasks at densities ranging from 80,000 to 520,000 cells/cm2. Hepatocytes were resuspended for 15 sec at 20-min intervals by placing the flasks on a timer controlled linear shaker. At time points ranging from 8 to 24 hr, hepatocyte aggregates were imaged via light microscopy. Mean spheroid diameter and shape factor were determined using computer analysis of captured images. Spheroid diameter could be controlled within the range of 60 to 240 microns. For long-term evaluation, spheroids were microencapsulated and cultured for 21 days under perfusion conditions. Encapsulated spheroids secreted albumin at rates comparable to collagen sandwich control cultures for at least 14 days, with peak rates (approximately 80 microns/day/10(6) cells) exhibited after culture medium changes. The results show that controlled, high efficiency hepatocyte aggregation can be accomplished in as little as 8 hr, and that the encapsulated spheroids exhibit long-term in vitro function.

Feasibility of a photosynthetic artificial lung.

The success of extracorporeal membrane oxygenation (ECMO) for the treatment of acute respiratory failure has led to consideration of the development of a more portable, and perhaps even implantable, artificial lung. The authors suggest a bioregenerative life support system that includes a photo-synthetic organism that can remove CO2 and produce O2 in the presence of an energy source. To build a model of such a photosynthetic artificial lung, the photosynthetic capability of a high temperature strain of the algae Chlorella pyrenoidosa was maximized at a cell density of 25 million cells/ml to serve as the O2 producer and CO2 remover. The "patient" in this model was comprised of 1 L of medium or 350 ml of blood, interfaced with the photosynthetic system across a gas transfer membrane. The experiments demonstrated the ability of the plant cells to supply O2 and remove CO2 from the "patient" with a maximum rate of 0.55 mmoles/L/hr under the most favorable measured operating conditions. The projected rate of 1.0 mmoles/L/hr required for physiologic applications is not totally ab absurd idea, with a slightly modified set-up. Modifications may be in the form of regulating the photosynthetic pathway or genetically engineering a hybrid strain with enhanced O2 producing and suppressed photoinhibition capacity.

Evaluation of contrast media for bronchography.

BACKGROUND: Bronchography is occasionally needed for the evaluation and management of some congenital pulmonary anomalies as well as some acquired diseases, usually of the tracheo- bronchial tree. There is currently no effective, approved contrast agent for this imaging techniq ue. OBJECTIVE: We evaluated five agents (barium sulfate, iohexol, propyliodone oily, propyliodone aqueous, and perflubron) in terms of image quality, histologic changes, and effects on hemodynamics, blood gases, and standard laboratory tests in New Zealand White rabbits. MATERIALS AND METHODS: Animals were anesthetized and intubated. Each contrast agent (0.25 ml/kg) was administered intratracheally. Three animals in each group had intravenous lines placed for blood sampling and blood pressure monitoring and were sacrificed at 1 h. An additional three animals for each agent were sacrificed at 24 h and 1 week after imaging. Blood samples were taken immediately before contrast instillation and at 1 h postbronchography. Fluoroscopic images were recorded on standard VHS video tape and evaluated in blind fashion. Segments of lung tissue and bronchi were obtained for histologic examination. RESULTS: Necrosis and/or inflammatory infiltrates were noted in 78 % of the bronchograms performed with propyliodone aqueous, 67 % with propyliodone oily, 55 % with perflubron, and 33 % with iohexol 120, 240 and 350. No histologic damage was observed with barium. The propyliodones gave the best-quality imaging results and the most histologic changes. Iohexol, in any concentration, gave the least acceptable images and a moderate number of histologic changes. Barium sulfate demonstrated acceptable images with virtually no histologic changes. CONCLUSION: From the histologic and imaging results, barium is the best available contrast material for bronchography.

Carotid artery and jugular vein ligation with and without hypoxia in the rat.

A continuing concern about the use of extracorporeal membrane oxygenation (ECMO) is the cannulation of the common carotid artery or the internal jugular vein. The authors investigated the changes that might occur in the brain with neck vessel ligation in the normal and the hypoxic rat. Two groups of 60 rats each were studied. The first group was divided into three subgroups of 20 animals each. Subgroup 1 (HH) was hypoxic both 24 hours before and 24 hours after operation. Subgroup 2 (HN) (the ECMO model) was hypoxic before operation and recovered for 24 hours in room air. Subgroup 3 (NN) underwent the entire procedure in room air. For each oxygen environment, four different operations were performed: carotid artery ligation, jugular vein ligation, carotid artery and jugular vein ligation, and dissection of the vessels without ligation (sham). Thus each subgroup was further divided into four sub-subgroups based on the operation performed. Rats were again anesthetized after a 24-hour recovery period and killed using low, blunt cervical dislocation. In the first group of 60 rats, the skull was opened and the brain was carefully removed from the cranial vault and placed in a fixative. The brains were placed in a small magnetic resonance imaging (MRI) head coil in groups of five and scans were obtained to provide T1 and T2 images that correlated with histological sections. MRI scans were reviewed in random, blinded fashion by an imager unaware of how these animals had been treated. The brains were then sectioned coronally at six corresponding levels: frontal, mid and posterior cerebrum, midbrain, pons, and medulla. Histological examination was performed in blinded fashion. The number of lesions (usually ischemic as noted by a decrease in the number of neurons) was totaled for each area of the brain. There were no differences that were consistent or statistically significant in the MR images of brains removed from the head, although it would appear that rats with jugular vein and carotid artery ligation were relatively protected. In the HN group jugular vein ligation was worst, and adding carotid artery ligation was best. In the histological studies the NN group had significantly more lesions than the HH group (P < .01). The second group of 60 rats was divided and treated as the first group in all respects except that MRI was conducted immediately after death on intact heads, and no histological studies were performed. This was done to control for lesions that might have been produced by removal of the brains from the skulls. In this group all findings were right sided. One animal in the HN group showed midcerebral white matter edema after jugular and carotid ligation. Focal anterior cerebral edema was seen in another animal (HH) after isolated carotid ligation. An occipital infarct was found in one animal (HH) after both carotid and jugular ligation. The authors conclude that neck vessel ligation in the hypoxic or normoxic rat causes only occasional and sporadic brain injury much as is seen clinically in newborn ECMO patients.