Histopathological observations in the brains of children exposed to inhalational anesthetic agents: a retrospective autopsy-based study.

BACKGROUND: Numerous animal models have demonstrated neuronal damage resulting from anesthetic exposure in the developing brain. Studies have shown a relationship between anesthetic exposure and brain hypoxia, neurodegeneration and apoptosis. The relevance of data derived from controlled experimental studies to human neuropathology is a subject of debate. This study compares histopathological findings in post-mortem brain tissue specimens from children with and without exposure to inhalational anesthetic agents. METHODS: Autopsy reports were reviewed. Patients were divided into exposure and non-exposure groups defined as any procedure involving inhalational anesthetic agents. A retrospective chart review was performed collecting pathological findings of the brain. The autopsy results examined the presence of twelve different histopathological parameters reflecting morphologic changes in thirteen regions of interest in the central nervous system. RESULTS: Post-mortem neuropathological findings were analyzed. Thirteen different areas were focused upon and changes were categorized into twelve histopathological parameters. Gliosis, which was confirmed by immunohistochemical staining for glial fibrillary acidic protein, was more prevalent in the exposure group (N.=48) compared to the non-exposure group (N.=20) (P<0.05). CONCLUSION: The role of anesthetic neurotoxicity is not well understood. Numerous animal models have demonstrated neuronal apoptotic changes linked to anesthetic exposure, there is no tangible evidence supporting this relationship in humans. Our analysis demonstrates histopathological brain changes in children with anesthetic exposure not seen in the non-exposed group. Analysis was based on histopathological parameters representative of salient morphological findings of injury, which were encountered in anatomically divergent regions. Gliosis was the only statistically significant finding in post-mortem brain samples of patients who had received anesthetics.

Supramitral ring: an unusual cause of congenital mitral stenosis. Case series and review.

Supramitral ring, also known as membranous supravalvular mitral stenosis is a rare cause of congenital mitral stenosis, with less than 100 cases appearing in the literature since its first description in 1902. We present a small series encountered at the university medical center during the last five years. The natural history of the condition is reviewed along with diagnostic tools, aspects of surgical repair, and anesthetic technique that facilitates early extubation and ICU discharge.

Intentional puncture of the dural space as an aid to epidural placement in a morbidly obese parturient.

OBJECTIVE: In this case report the authors discuss a technique occasionally employed at their institution to aid in identification of the epidural space in morbidly obese parturients. CASE REPORT: A 29-year-old primagravida, with a body mass index of 90 (155 cm tall, 215 kg) presented for induction of labor. A 27-ga. Sprotte spinal needle was intentionally passed through a Weiss epidural needle and into the subarachnoid space to confirm placement of the Weiss needle in the epidural space. An epidural catheter was then placed which functioned well for labor and subsequent caesarian delivery. CONCLUSIONS: In selected patients, intentional puncture of the dura can aid in confirmation of the epidural space.

Effect of hyperbaric oxygen on striatal metabolites: a microdialysis study in awake freely moving rats after MCA occlusion.

We have shown that hyperbaric oxygen (HBO) reduced cerebral infarction in rat middle cerebral artery occlusion model (MCAO). The present study was undertaken to evaluate the effect of HBO on ischemic striatal metabolites at different times after MCAO and reperfusion. A rat MCAO model was produced via the intraluminal filament method. After 2 h of occlusion the suture was removed and reperfusion was allowed. The rats were sacrificed at 24 h after reperfusion. HBO treatment was administered by putting rats in the HBO chamber at 3 atmospheres absolute (ATA) HBO for 1 h. Glucose, lactate, pyruvate, and glutamate in striatal extracellular fluid were collected and measured by a microdialysis system at 7, 10, and 24 h after reperfusion. Glucose, pyruvate and glutamate concentrations were increased after reperfusion. HBO treatment decreased glucose, pyruvate, and glutamate almost to the control level (preocclusion level). The lactate concentration remained unchanged after ischemic/reperfusion and after HBO treatment. This study suggested that altered brain energy metabolites and excitatory amino acids occurred during cerebral ischemia and and HBO regulated these striatal metabolites, which might contribute to the protective effect of HBO in cerebral ischemia.

In vitro effects of hyperbaric oxygen on sickle cell morphology.

STUDY OBJECTIVE: To determine in vitro whether hyperbaric oxygen has any effect on the morphology of sickle cells. DESIGN: Prospective, in vitro, study, with each patient sample serving as its own control. SETTING: University medical center. PATIENTS: 10 children known to be homozygous for hemoglobin S. INTERVENTIONS: Blood samples were obtained from 10 children during routine visits to the University sickle cell clinic. Blood samples were exposed to room air to achieve maximal sickling. Each sample was divided into control and study aliquots, and the study portions placed in a research hyperbaric chamber with 100% oxygen at 3 atmospheres absolute pressure for 15 min. Then smears were prepared from all samples at regular intervals and examined by technicians in the sickle cell clinic who were blinded as to the details of this study. MEASUREMENTS: Percentages of normal cells, sickle cells and sickle forms were reported. Data were interpreted using t-tests. MAIN RESULTS: Hyperbaric oxygen appeared to have no effect on sickle cell morphology. Percentages of each cell type were unaffected by hyperbaric oxygen exposure. CONCLUSIONS: Hyperbaric oxygen appears to have no effect on the morphology of sickle cells in vitro. Other mechanisms may account for the beneficial clinical effects of hyperbaric oxygen in sickle cell crisis, although in vivo studies are warranted.

Sildenafil (viagra) facilitates weaning of inhaled nitric oxide following placement of a biventricular-assist device.

Sildenafil is a selective phosphodiesterase type 5 inhibitor used in the treatment of erectile dysfunction. We report the use of sildenafil to blunt the rebound pulmonary hypertension seen following withdrawal of inhaled nitric oxide (NO) and milrinone. The relatively long duration of sildenafil's action on pulmonary artery pressures and lack of systemic hemodynamic effect make it an attractive option to facilitate weaning of inhaled NO.

Dual effect of HBO on cerebral infarction in MCAO rats.

Various reports in the literature have shown that hyperbaric oxygen (HBO) reduces cerebral infarction both in animals and humans. After the initial ischemic insult, however, initiating HBO treatment at different intervals has yielded conflicting results. The present study was undertaken to determine the optimal therapeutic window in which to start HBO treatment for cerebral infarction after transient focal ischemia. In this study, the operator occluded the middle cerebral artery (MCA) of anesthetized rats by introducing a blunted nylon filament into the proximal MCA from the dissected external carotid artery. When the operator removed the filament after 2 h, focal ischemia and reperfusion occurred. The operator then placed the rat in the HBO chamber and administered 3 atm absolute HBO for 1 h according to the protocol. The rat was killed 24 h after reperfusion, and the percentage of infarction (infarct ratio) was calculated by dividing the infarction area by the total area of the ipsilateral hemisphere. The results showed that the percentage of infarcted area decreased significantly (P < 0.05) both in the 3- (7.59%) and 6-h (5.35%) HBO-treatment groups compared with the control (no treatment) group (11.34%). However, the percentage of infarcted area increased significantly (P < 0.01 and P < 0.05, respectively) both in the 12- (23%) and 23-h (20%) treatment groups. The results of this study suggest that applying HBO within 6 h of ischemia-reperfusion injury could benefit the patient but that applying HBO 12 h or more after injury could harm the patient.

Falsely elevated bispectral index during deep hypothermic circulatory arrest.

A 2-month-old infant underwent repair of a ventricular septal defect under deep hypothermic circulatory arrest. Bispectral index and EEG suppression ratio were evaluated using an Aspect BIS monitor. Erroneous readings from the monitor could have led to a potentially dangerous alteration in surgical and anaesthetic management.

Preoperative exposure to calcium channel blockers suggests increased blood product use following cardiac surgery.

PURPOSE: In this study the authors reviewed the medical records of a random sample of patients undergoing coronary artery bypass grafting (CABG) during the preceding ten years at University Medical Center. The purpose of this study was to evaluate the impact of exposure to calcium channel blockers (CCB's) on blood product use following cardiopulmonary bypass (CPB). DESIGN: Retrospective medical record review. SETTING: University hospital. PARTICIPANTS: 527 patients undergoing CABG or re-do CABG. INTERVENTIONS: The medical records of approximately 50% of patients undergoing CABG or re-do CABG at University Medical Center between 1988 and 1998 were randomly selected by the medical records librarian for review. Preoperative medications, bypass time and temperature, and blood product use were recorded. RESULTS: Of the 527 patients studied, 309 (59%) had no exposure to CCB's. 218 (41%) were on CCB's at the time of admission. Patients who were on CCB's had an average 12.5 (+/- 1.0) blood product units transfused following bypass whereas those not on CCB's had an average 8.7 (+/- 0.6) units transfused (p < 0.001). Use of packed red blood cells (p < 0.001), fresh frozen plasma (p = 0.018) and platelets (p = 0.023) were each individually significantly increased. CONCLUSIONS: In this study, it appeared that patients exposed to CCB's before cardiac revascularization received significantly more blood products than those who were not exposed to CCB's. Because of the limitations imposed by retrospective studies, further prospective studies are warranted to define the clinical significance of CCB use in the perioperative period.

Optison (FS069) disrupts the blood-brain barrier in rats.

Optison is a new echocardiographic contrast agent, designed for IV injection, that is very useful in delineating cardiac structures during ultrasound examination. Because Optison could be a valuable adjunct in the diagnosis and evaluation of congenital heart disease, this study was undertaken to assess its effects on the blood-brain barrier when introduced directly in the cerebral circulation, as might occur with some congenital lesions. In this study, Sprague-Dawley rats were anesthetized, and Optison, at various dosages, was injected into the carotid artery. After this, Evans blue dye, a marker for blood-brain barrier disruption, was injected at different time intervals. Gross and histologic examination of the animals' brains revealed disruption of the blood-brain barrier that appeared to be Optison-dosage-dependent. Although the mechanism for this disruption is unclear, it may be related to the use of octofluoropropane gas used in the Optison as a contrast medium. Further studies are necessary to determine the pathologic consequences of Optison's effects on the blood-brain barrier.

Isolated cardiac metastasis of cervical carcinoma presenting as disseminated intravascular coagulopathy. A case report.

BACKGROUND: An isolated cardiac metastasis from cervical carcinoma is very rare. This report describes the unusual presentation in a patient diagnosed and successfully treated for stage IB squamous cell carcinoma of the cervix, presenting six months later with disease metastatic to the heart. CASE: A 44-year-old woman presented with hand swelling and bruising. She had undergone successful surgical treatment of a stage IB squamous cell cervical carcinoma six months previously. Computed tomography revealed a large mass in the right ventricle, confirmed by echocardiography. The patient underwent surgery, where the mass was biopsied and debulked under a cardiopulmonary bypass. Frozen section confirmed metastatic squamous cell carcinoma. The patient was discharged with follow-up radiation and chemotherapy. CONCLUSION: All women with myocardial abnormalities and a history of squamous cell carcinoma of the cervix should be suspected of developing a myocardial metastasis until proven otherwise.

Interaction of an implanted pacemaker with a transesophageal atrial pacemaker: report of a case.

We report an interaction of a transesophageal atrial pacemaker (TAP) with a permanently implanted pacemaker in a cardiac patient who had undergone ablative therapy for atrial tachyarrhythmia 5 years earlier. The patient's permanent A-V pacemaker was completely inhibited by the TAP, and there was loss of ventricular contractions and blood pressure. The patient required epicardial A-V pacing to overcome the programmed heart rate of 76 bpm. We describe alternative methods to epicardial pacing. We also recommend close inspection of the chest radiograph, which often can reveal the serial numbers of the implanted pacemaker, as a means of identifying the device's functions and programming.