Search PubMed⌕ Search

Biomedical subjects

G M Graeber

Publications and source records attributed to G M Graeber.

At least 37 records · Page 2Linked to original sources
PubMed1994

Experimental amitriptyline poisoning: treatment of severe cardiovascular toxicity with cardiopulmonary bypass.

STUDY OBJECTIVE: To compare cardiopulmonary bypass (CPB) with more conventional therapy in the treatment of severe amitriptyline poisoning. DESIGN: Prospective, randomized, controlled, laboratory investigation. INTERVENTIONS: Profound cardiovascular toxicity was induced in 20 anesthetized Yorkshire swine (72 +/- 8.3 kg) by amitriptyline infusion at 0.5 mg/kg/min. Ventilation was adjusted to keep arterial pH at 7.50 +/- 0.05 and the PCO2 at 35 mm Hg. The swine were randomized in a 1:1 ratio to one of two groups, CPB or control. Both groups received amitriptyline infusion until they experienced near-lethal toxicity, defined as a systolic blood pressure below 30 mm Hg for one minute. The control group was then given supportive treatment, including IV fluids, sodium bicarbonate, vasopressors, and standard pharmacologic (advanced cardiac life support) interventions. Control animals failing to respond to supportive measures after five minutes were given open-chest cardiac massage for 30 minutes or until the return of spontaneous circulation. The CPB group received only mechanical support by CPB for 90 to 120 minutes. No sodium bicarbonate, antiarrhythmics, or cardiotonic agents were provided to the CPB group during this resuscitation. RESULTS: All 20 animals experienced cardiac conduction delays, dysrhythmias, and progressive hypotension within 30 minutes of receiving IV amitriptyline at 0.5 mg/kg/min. The ten swine receiving CPB as treatment for cardiovascular toxicity were able to completely correct the dysrhythmias, cardiac conduction abnormalities, and hypotension produced by the amitriptyline; however, only one of ten control animals could be resuscitated (P = .0001). Nine of ten swine treated with CPB were easily weaned off bypass without any pharmacologic intervention; however, one required norepinephrine to be weaned. All 11 resuscitated swine were able to be salvaged. CONCLUSION: CPB improved survival in our swine model of severe amitriptyline poisoning.

Amitriptyline↗
PubMed1994

Thoracoscopic resection of bilateral metastatic sarcomas causing spontaneous pneumothorax.

Pulmonary metastases from soft tissue sarcomas may present with spontaneous pneumothorax. Metastatectomy via thoracotomy or median sternotomy has been the procedure of choice. We present a patient with bilateral spontaneous pneumothorax secondary to metastatic angiosarcoma where staged video-assisted thoracic surgery using the thoracoscope was used to successfully resect the tumors.

Aged↗
PubMed1993

Myocardial performance after contusion with concurrent hypovolemia.

Myocardial contusion may present as a benign nonclinical event or a life-threatening emergency. Although cardiac output is recognized to be decreased with major contusion, the contribution of hypovolemic shock to myocardial dysfunction is unclear. This study was designed to evaluate the relationship between myocardial contusion and hypovolemic shock. After Sprague-Dawley rats were anesthetized, contusions were administered at either 80 psi or 120 psi. Half of each group then underwent hypovolemic shock. After 24 hours of recovery, cardiac hemodynamics were studied in each subgroup using the Neely-Langendorff apparatus. Isoenzymes and histology were evaluated as well. The data showed that rats undergoing hypovolemic shock in each subgroup had a significant decrease in cardiac output when compared with their controls. This decrease was more pronounced in the 120-psi group. Cardiac isoenzyme levels were elevated in all groups. Microscopic evaluations showed contusion in the controls and necrosis in the shock groups. Patients whose injuries are compatible with myocardial contusion and hypovolemic shock should be resuscitated quickly and evaluated for myocardial dysfunction secondary to infarction.

Animals↗
PubMed1993

Use of heparin-coated cardiopulmonary bypass.

A 49-year-old man with unstable angina and a history of severe anaphylaxis to seafood and intravenous iodine needed myocardial revascularization. Because of concern of an intraoperative protamine reaction, preoperative treatment was instituted with steroids and with H1 and H2 blockers. Revascularization was accomplished using a heparin-coated cardiopulmonary bypass circuit. Complement activation and postoperative bleeding were minimal. Heparin-coated cardiopulmonary bypass is a safe, effective technique of bypass in select patients.

Anaphylaxis↗
PubMed1993

The role of thoracoscopy in thoracic trauma.

The advent of video-assisted thoracic surgical procedures has caused many thoracic surgeons to reevaluate their approach to the management of diseases of the chest. The management of traumatic thoracic injuries is an area in which thoracoscopic techniques may have significant impact. The current role of thoracoscopy in the diagnosis and therapy of thoracic trauma continues to evolve. This review considers the currently accepted diagnostic and therapeutic applications of thoracoscopy in the management of these patients. The technique of thoracoscopy as it applies to the trauma patient is also discussed, as well as the future and expanding applications of thoracoscopy in this setting.

Anesthesia, General↗
PubMed1993

Effects of insufflation on hemodynamics during thoracoscopy.

Thoracic procedures once requiring open thoracotomy are now being performed with video-assisted thoracoscopy. To visualize adequately the intrathoracic structures, creation of an artificial pneumothorax by carbon dioxide insufflation under positive pressures has been advocated. We hypothesized that positive-pressure insufflation during thorascopy would cause significant hemodynamic compromise. Eight healthy female pigs underwent general endotracheal anesthesia and placement of monitoring lines. After placement of a thorascope, baseline hemodynamic measurements were obtained at 0 mm Hg (atmospheric pressure). Measurements were taken randomly at 5, 10, and 15 mm Hg using carbon dioxide insufflation after stabilization at each pressure. Data were analyzed using Page's test for noparametric variables. Insufflation pressures of 5 mm Hg or greater resulted in significant decreases in cardiac index, mean arterial pressure, stroke volume, and left ventricular stroke work index, whereas central venous pressure increased (p < 0.001). Changes in heart rate were not significant. We do not recommend routine positive-pressure insufflation during thorascopy because of the significant hemodynamic compromise in our experimental model.

Animals↗
PubMed1993

Effects of flunarizine on neurological recovery and spinal cord blood flow in experimental spinal cord ischemia in rabbits.

BACKGROUND AND PURPOSE: The lipophilic calcium channel antagonist flunarizine has been demonstrated to be neuroprotective in several models of cerebral ischemia. Ischemic spinal cord injury may have a similar pathophysiology and hence may respond in a similar fashion. This study was designed to investigate the effects of pretreatment with flunarizine on systemic hemodynamics, spinal cord blood flow, and neurological recovery in a rabbit model of ischemic spinal cord injury. METHODS: New Zealand White rabbits were anesthetized with ketamine and xylazine and instrumented for systemic blood pressure monitoring and spinal cord blood flow measurements using the microsphere method. After pretreatment with flunarizine or vehicle, ischemic spinal cord injury was created selectively in the caudal regions of the spinal cord by cross-clamping the abdominal aorta for a period of 25 minutes. Spinal cord blood flow was measured before, during, and 15 minutes after cross-clamp removal. Animals were allowed to recover and were graded neurologically at 18 and 24 hours after ischemia. RESULTS: Flunarizine injection was associated with hypotension that was both transient and dose related. Animals pretreated with flunarizine 0.4 mg/kg had significantly improved neurological recovery scores at 18 hours after ischemia (P = .017) compared with vehicle controls. At 24 hours this effect was lessened (P = .095); however, 60% of flunarizine-treated animals retained their ability to hop, whereas all of the vehicle-treated animals were nonambulatory. CONCLUSIONS: Flunarizine has a protective effect on neurological recovery after experimental ischemic spinal cord injury. The therapeutic window is narrow, and dosing is limited by untoward hypotension. The mechanism of protection likely involves inhibition of pathological cytosolic calcium accumulation rather than a direct effect on vascular smooth muscle.

Animals↗
PubMed1993

Current management of esophageal impactions.

We analyzed our experience at a university medical center from 1977 to 1990 to assess our success in using esophagoscopy and related treatments for removing esophageal impactions. There were 157 episodes of impaction in 150 patients, consisting of 39 pediatric and 111 adult patients. In the pediatric cases, foreign bodies were most often the cause of impaction, while adult cases were usually caused by food or bones. Esophagoscopy was performed successfully in 32 of 34 pediatric patients in which it was attempted; there was only one complication. Other forms of therapy that were infrequently tried met with variable results. Esophagoscopy was successful in removing the impaction in 104 of 109 attempts in adults. Two perforations occurred, with one resulting in death. Various other methods achieved success in the remaining patients. The data suggest that esophageal impaction can be treated successfully by endoscopy with very low morbidity and mortality.

Adolescent↗
PubMed1993

Video-assisted thoracoscopy: a major advance in diagnosis and treatment of intrathoracic pathology.

The diagnosis and treatment of intrathoracic disease often requires open thoracotomy. Patients who are immunocompromised, have poor pulmonary function, or have coronary artery disease may not tolerate this procedure well. With the advent of small video cameras, fiberoptics, and compatible instrumentation, thoracoscopy is now a viable option to open thoracotomy. This procedure is being performed with increasing frequency, and has achieved excellent results. The intrathoracic image, which previously was only available to the operating surgeon, is captured by a small video camera on the end of the scope. The image is projected simultaneously on several television monitors in the operative suite so that all members of the operative team can see exactly what the surgeon sees. By using such technologies, intrathoracic diagnostic and therapeutic procedures, which previously required some type of open thoracotomy, may now be performed through several small ports placed through diminutive surgical incisions. This article describes three case reports which demonstrate some of the successful applications of video-assisted thoracoscopy, and reviews the diagnostic and therapeutic indications for video-assisted thoracoscopy.

Adult↗
PubMed1991

The healing sternum: a comparison of osseous healing with wire versus rigid fixation.

Although median sternotomy is used for most cardiac procedures, postoperative dehiscence remains a serious and persistent problem. This investigation was designed to assess new bone formation and sternal healing across the linear osteotomy of the sternum and to determine if rigid fixation would enhance bony healing and thus decrease unfavorable sequelae. To test this hypothesis, 14 skeletally mature baboons (Papio anubis) underwent standard median sternotomy; seven sternotomies were closed with interrupted 24-gauge cerclage wires, and seven, with thin Vitallium compression miniplates and transverse lag screws. The sterna from each group were harvested en bloc at 4 and 8 weeks, radiographed, processed, and serially sectioned and stained for histomorphometry to assess the quantity of new bone across the linear osteotomy. Clinical stability was superior with the plated and lag screw group at 4 weeks; however, by 8 weeks, no clinical difference between treatments was apparent. Histomorphometric analysis indicated that the linear osteotomy gap treated with plates and screws was less than the gap associated with the wire group. Rigid fixation of the sternum resulted in earlier union with primary osseous healing, suggesting greater inherent stability. these factors may decrease adverse sequelae for this procedure.

Animals↗
PubMed1991

Are sutures better than staples for closing bronchi and pulmonary vessels?

Little is known about the strength of suture lines and stapled closures of the bronchus, pulmonary arteries, and pulmonary veins. This experiment tested and compared the hydrostatic leakage point of each of these structures when closed by either sutures or staples. Fourteen fresh mature porcine cadavers and 8 human cadavers of age greater than 50 years were studied to determine whether the pig could be used as an appropriate model for future in vivo studies. Cadavers were selected so that closures depended only on the material used and not on any clot reinforcing the closure lines. The results of the study suggest that staple closure of the pulmonary artery and the main bronchus is as secure as suture closure. Pulmonary veins leak at a lower pressure when closed with staples; however, this pressure far exceeds physiological pressures in the left atrium. The data also suggest that the pig is an appropriate model for approximating conditions found in patients and is a good model for chronic studies comparing suture and staple closures.

Bronchi↗
PubMed1990

Pharyngoesophageal perforation after blunt neck trauma.

Pharyngoesophageal perforation secondary to blunt neck trauma is an uncommon injury that can cause serious morbidity and mortality if not recognized and treated. Pharyngeal perforation secondary to blunt trauma sustained while boxing is reported. Review of the world literature found 10 cases of pharyngoesophageal perforation secondary to blunt neck trauma. Analysis of these cases indicates that perforations less than 2 cm and limited to the pharynx may be treated medically with close observation. Large perforations and those perforations that extend to the esophageal inlet or involve the esophagus exclusively are best treated surgically.

Adolescent↗
PubMed1990

Hemodynamics and coronary blood flow during experimental aortic valvuloplasty: comparison of the dual versus the single catheter methods.

During thoracotomy 12 anesthetized swine were instrumented and valvuloplasty catheters were positioned at the aortic anulus. Thirty-second occlusions of the left ventricular outflow tract were performed with a single catheter (n = 34) and with simultaneous inflation of dual catheters (n = 47). Left anterior descending coronary artery blood flow fell to minimums of 15% of baseline flow (SD 13.9%) during single balloon occlusion and to 63.8% of baseline flow (SD 22.8%) during dual balloon occlusion. Main pulmonary artery flow fell to minimums of 13.6% of baseline flow (SD 17.3%) during single balloon occlusion and to 66.9% of baseline flow (SD 18.3%) during dual balloon occlusion. Femoral artery systolic pressure dropped to 20.1% of baseline pressure (SD 5.6%) during single balloon occlusion and to 82.6% of baseline pressure (SD 8.1%) during dual balloon occlusion. During single balloon occlusion, 8.5 (SD 3.5) premature ventricular contractions were observed and 2.8 (SD 1.6) premature ventricular contractions occurred during dual balloon occlusion. After deflation of the valvuloplasty catheters, the time to return of baseline flow in the left anterior descending coronary artery was 28.4 second (SD 23.2 seconds) with the single balloon method and 4.8 seconds (SD 3.7 seconds) with the dual balloon method. All of these differences were statistically significant (p less than .001). During occlusion of the left ventricular outflow tract by dual valvuloplasty catheters, there were better hemodynamics, higher coronary blood flows, and fewer premature ventricular contractions than during occlusion by a single catheter. After occlusion by dual catheters, returns to baseline coronary flows were more rapid than after single catheter occlusions. These data may have application to clinical aortic valvuloplasty.

Angiography↗
PubMed1990

Serum creatine kinase and lactate dehydrogenase changes after anterior approaches to the thoracic and lumbar spine.

Ten patients undergoing anterior approaches to the thoracic and lumbar spine had prospective determinations of serum creatine kinase, lactate dehydrogenase, and their myocardial-associated isoenzymes (CK-MB and the LD-1/LD-2 ratio). None of these patients experienced postoperative myocardial infarction. Skeletal muscle injury associated with anterior spinal surgery resulted in significant elevations of serum CK-MB on postoperative Day 1; however, the LD-1/LD-2 ratio did not change significantly. Although false-positive elevations of serum CK-MB occurred, no patient had a CK-MB value exceeding 50 IU/liter combined with an LD-1/LD-2 ratio exceeding 1.0 (so-called "flipped LD" pattern). In evaluating suspected postoperative myocardial infarction, the authors recommend determining the isoenzymes of both serum creatine kinase and lactate dehydrogenase. In postoperative patients, elevations of CK-MB exceeding 50 IU/liter combined with an LD-1/LD-2 ratio exceeding 1.0 should not be attributed to skeletal muscle injury alone after anterior approaches to the thoracic and lumbar spine.

Adolescent↗