John C. Laschinger

Improved results from a standardized approach in treating patients with necrotizing fasciitis.

Necrotizing fasciitis has been associated with significant morbidity and mortality. Thirty-three patients were studied over a 3-year period. Predisposing factors included intravenous drug abuse (30%), diabetes (21%), and obesity (18%). Severe pain (94%) and abnormal temperature (88%) were present, whereas laboratory data and x-ray were nonspecific. Gram-positive organisms were most frequently recovered (B-hemolytic streptococcus 45%). Treatment consisted of antibiotics, surgical debridement, re-exploration 24 hours before surgery, nutritional support, and early soft tissue coverage as needed. Mean duration from admission to operation was 43 hours. The average number of operative debridements was three and the average length of hospitalization was 47 days. Patients operated on less than 12 hours from admission or greater than 48 hours had shorter hospital stays (36 and 38 days). The critical time period was 12-48 hours after admission; all deaths and amputations were in this group and the average hospital stay was 62 days (p less than 0.05). The number of operations did not correlate to hospital stay. Despite antibiotics and aggressive debridement, significant morbidity exists if operation is delayed more than 12 hours. Methods of early detection such as local bedside diagnostic incision and fascial inspection may be needed in high risk patients to further reduce the morbidity and mortality.

Measurement of spinal cord ischemia during operations upon the thoracic aorta: initial clinical experience.

Paraplegia has been an unpredictable, devasting complication following operations upon the thoracoabdominal aorta for over 30 years. The frequency ranges from 0.5% with operations for coarctation to as high as 15% following surgery for thoracoabdominal aneurysms. Both uncertainty and controversy exist about the value of different protective methods during aortic crossclamping (AXC): heparinized shunts, partial bypass, and reimplantation of intercostal arteries. This report describes the authors initial clinical experience with a highly sensitive indicator of spinal cord ischemia, somatosensory evoked potentials (SEP) in an attempt to prevent paraplegia associated with surgical procedures on the thoracoabdominal aorta. Seven consecutive patients (one coarctation, five thoracic aneurysms, one thoracoabdominal aneurysm) underwent continuous operative monitoring of SEP. Cortical response to simultaneous electrical stimulation (20 mAmps, 0.6 mSec., 2.3 cps) of both the right and left posterior tibial nerves was recorded before, during, and after AXC, and following operation. When ischemic changes were detected by SEP, increasing distal circulation by different maneuvers (heparinized shunt, femoral-femoral bypass, reimplantation of intercostal arteries) reversed these changes. In two patients with thoracic aneurysms, ischemic changes appeared within three minutes after AXC and all potentials disappeared in nine minutes. Rapid insertion of a graft (AXC 28 and 37 minutes) resulted in SEP return 40 minutes following restoration of flow. These changes were prevented by a heparinized shunt in two patients, femoral/femoral bypass in one, and T8-T9 intercostal reimplantation in one. No SEP changes occurred in the patient with coarctation. No postoperative neurologic complications occurred. Continuous operative monitoring of SEP has exciting possibilities for preventing paraplegia. It is simple, highly sensitive, and seems to provide a precise measurement of adequacy of circulation to the spinal cord.

Prevention of Ischemic Spinal Cord Injury Following Aortic Cross-Clamping: Use of Corticosteroids

Prior to proximal aortic cross-clamping, baseline measurements of spinal cord blood flow and function were done. Blood flow was evaluated with radioactive microspheres and function determined by assessment of somatosensory evoked potential (SEP). Group 1 (N = 6) animals had aortic cross-clamping for 5 minutes after ischemic spinal cord dysfunction (SEP loss) was documented. Group 2 (N = 9) underwent aortic cross-clamping for 10 minutes after loss of SEP. Group 3 (N = 6) also underwent 10 minutes of cross-clamping after initial SEP loss, but were treated intravenously with methylprednisolone (30 mg per kilogram of body weight) 10 minutes prior to cross-clamping and again 4 hours postoperatively. After release of the cross-clamp, the animals were allowed to recover and serial evaluations of spinal cord blood flow and neurological status were carried out for seven days. Group 1 animals recovered uneventfully without evidence of neurological injury. Group 2 animals sustained a 67% incidence of permanent spastic paraplegia (p = 0.02 versus Group 1). In contrast, methylprednisolone-treated animals sustained no clinically detectable neurological injury (p = 0.02 versus Group 2). Measurements of spinal cord blood flow at the time of SEP loss revealed similar degrees of spinal cord ischemia in all groups. No significant differences were observed in the duration of aortic cross-clamping prior to SEP loss among the three groups. The data indicate that short periods of cross-clamping (5 minutes) following SEP loss are well tolerated, whereas longer periods (10 minutes) are associated with a high incidence of paraplegia.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental and clinical assessment of the adequacy of partial bypass in maintenance of spinal cord blood flow during operations on the thoracic aorta.

We studied both experimentally and clinically the efficacy of partial bypass techniques in maintaining spinal cord blood flow and physiological function during surgical procedures on the thoracoabdominal aorta. We attempted to define the level of distal aortic pressure required to safely ensure normal neurological function in the absence of critical intercostal occlusion. Six dogs underwent left thoracotomy with baseline measurements of spinal cord blood flow and spinal cord impulse conduction (somatosensory evoked potentials). Following exclusion of the entire descending thoracic aorta from the left subclavian artery to the T-13 level, partial left atrium-femoral artery bypass was instituted, and baseline levels of proximal and distal aortic pressure were maintained during a 30-minute stabilization period. Mean distal aortic pressure then was progressively altered at 30-minute intervals to 100, 70, and 40 mm Hg. Measurements of spinal cord blood flow and somatosensory evoked potential were repeated at the end of each interval for comparison with baseline. No significant changes in spinal cord blood flow or somatosensory evoked potential were observed in any animal with a distal aortic pressure greater than or equal to 70 mm Hg. With a pressure of 40 mm Hg, normal flow and somatosensory evoked potentials were maintained in 5 of the 6 dogs. Loss of somatosensory evoked potential, with simultaneous loss of spinal cord blood flow at the T-6 level, occurred in 1 dog. Restoration of distal aortic pressure to 70 mm Hg in all animals resulted in immediate return of somatosensory evoked potential. Loss of somatosensory evoked potential routinely occurred in animals with a distal aortic pressure less than 40 mm Hg. Clinically, 9 patients have undergone operation for lesions of the thoracoabdominal aorta using shunt or bypass techniques. Normal somatosensory evoked potentials were preserved in 7 patients with maintenance of adequate distal aortic pressure (greater than or equal to 60 mm Hg) without evidence of postoperative neurological deficit. Two patients showed hypotensive somatosensory evoked potential loss (distal aortic pressure less than 40 mm Hg). Prolonged distal hypotension (85 minutes of aortic cross-clamping) in the latter resulted in paraplegia. We conclude that maintenance of a distal aortic pressure greater than 60 to 70 mm Hg will uniformly preserve spinal cord blood flow in the absence of critical intercostal exclusion. Should distal aortic pressure be inadequate, early reversible changes in the somatosensory evoked potential will alert the surgeon. Failure to institute measures to reverse these changes may result in paraplegia.

Experimental and clinical results with a simplified left heart assist device for treatment of profound left ventricular dysfunction.

During the last few years patients with profound heart failure following cardiac surgery have been managed with increasing success with the use of a variety of left heart assist devices. Although some previous experimental studies suggested that cannulation of the left ventricle was superior to that of the left atrium, present studies demonstrate that left atrial cannulation can effectively unload the left ventricle, and significantly decrease left ventricular work. Since 1978, a roller pump type of left heart assist device with cannulation of the left atrium and ascending aorta has been employed in 46 patients with severe postoperative cardiac failure. Twenty-one patients were successfully weaned from the device; 5 patients died within 90 days of removal of the device, and there were 2 other late deaths 4 months and 4 years postoperatively. There were 14 long-term survivors (6 months to 54 months). Thirteen of these patients are New York Heart Association class I or II, and 1 patient is New York Heart Association class III. Thus, satisfactory early and late results can be attained with this system. However, it has been postulated that if more complete left heart bypass were utilized, more patients would ultimately survive.RésuméDepuis quelques années, les malades ayant une défaillance cardiaque sévère après chirurgie cardiaque ont été traités avec un succès croissant en utilisant une pompe dassistance ventriculaire gauche modifiée. Bien que des études expérimentales suggèrent que la canulation du ventricule gauche ait des effets supérieurs à celle de loreillette gauche, cette étude démontre que la canulation auriculaire gauche peut de façon effective décharger le ventricule gauche, et diminue de façon significative le travail ventriculaire gauche. Depuis 1978 une pompe dassistance ventriculaire gauche à type de “pompe à galet,” avec canulation de loreillette gauche et de laorte ascendante, a été utilisée chez 46 malades présentant en post-opératoire une défaillance cardiaque sévère: 21 ont pu être sevrés avec succès de cette machine, 5 malades sont décédés au cours des 90 jours suivants, et 2 sont décédés plus tardivement, respectivement 4 mois et 4 ans après lintervention. Quatorze malades ont survécu à long terme (de 6 mois à 54 mois): 13 de ces malades étant en classe I ou II de la New York Heart Association, et un malade etant en classe III. Cest pourquoi, des résultats satisfaisants, précoces et tardifs, peuvent être obtenus par cette assistance. Quoi quil en soit on suppose que plus lassistance gauche est complète, plus le nombre de malades survivants sera important.ResumenEn los últimos años se ha logrado manejar con éxito creciente a los pacientes en falla cardiaca profunda después de cirugía del corazón con una variedad de artefactos de asistencia mecánica del corazón izquierdo. Aunque algunos estudios experimentales previos sugerían que la canulación del ventrículo izquierdo era superior a la canulación de la aurícula izquierda, estudios actuales demuestran que la canulación atrial izquierda puede descargar en forma efectiva al ventrículo izquierdo y disminuir significativamente su trabajo. Desde 1978 hemos empleado un aparato de asistencia mecánica del ventrículo izquierdo del tipo de bomba de rodillo, con canulación de la aurícula izquierda y la aorta ascendente en 46 pacientes con severa falla cardíaca post-operatoria. Veintiún pacientes fueron desahijados exitosamente del aparato; cinco pacientes expiraron dentro de los 90 días siguientes al retiro del aparato, y se presentaron otras dos muertes cuatro meses y cuatro años después de la operación. Hubo 14 supervivientes a largo término (seis meses a 54 meses). Trece de estos pacientes son Clase I o Clase II de la New York Heart Association, y uno es Clase III. Esto indica que se pueden lograr resultados satisfactorios precoces y a largo plazo con el sistema. Es nuestra impresión que con una más amplia utilization de estos aparatos de exclusión completa del corazón izquierdo en pacientes sometidos a cirugía cardiaca y en pacientes con infarto agudo del miocardio, se lograría el salvamento de un mayor número de casos.

Definition of the safe lower limits of aortic resection during surgical procedures on the thoracoabdominal aorta: Use of somatosensory evoked potentials

The technique of intraoperative monitoring of somatosensory evoked potentials was applied to a canine model of spinal cord ischemia in an attempt to determine the safe lower limits of aortic resection during thoracic aortic surgery. Fifteen animals underwent left thoracotomy with institution of partial left atrial/femoral artery bypass for maintenance of distal aortic perfusion after proximal descending thoracic aortic exclusion. In Group I animals (n = 6, control), no further interventions were performed so that the effect of exclusion of vessels noncritical to spinal cord blood supply could be assessed by measurements of spinal cord blood flow and somatosensory evoked potentials. In Group II animals (n = 8), the level of distal aortic exclusion was progressively lowered until loss of somatosensory evoked potential (critical vessel exclusion) occurred. The effect of critical vessel exclusion on spinal cord blood flow was then assessed. Exclusion of multiple vessels noncritical to spinal cord blood supply (Group I) had no effect on spinal cord blood flow or function (somatosensory evoked potentials). Exclusion of vessels critical to spinal cord blood supply resulted in significant spinal cord ischemia (83.4% flow reduction, probability [p] less than 0.05 versus baseline) and ischemic spinal cord dysfunction (loss of somatosensory evoked potential).(ABSTRACT TRUNCATED AT 250 WORDS)

Early Open Radical Commissurotomy: Surgical Treatment of Choice for Mitral Stenosis

Between 1967 and 1979, 411 patients underwent surgical treatment of isolated mitral stenosis at our institution. Open radical mitral commissurotomy was performed in 150 patients (1967-1978; mean follow-up, 46 months; range, 4 to 116 months). Mitral valve replacement using a porcine prosthesis was performed in 74 patients (1976-1979; mean follow-up, 23 months; range, 2 to 48 months). Mitral valve replacement with a cloth-covered Starr-Edwards prosthesis was performed in 187 patients (1967-1975; mean follow-up, 45 months; range, 2 to 106 months). Preoperative characteristics were similar in the three groups. The open commissurotomy and Starr-Edwards groups were followed up to 9 years and the porcine valve group up to 4 years, with 97% follow-up in each group. Life-table analysis (6-month intervals) of all postoperative complications revealed significantly greater complication-free survival for patients who had open radical commissurotomy compared with Starr-Edwards (p less than 0.05) valve replacement. Similar analysis of thromboembolic and warfarin-related complications revealed significantly fewer complications in commissurotomy patients. No significant differences were found (p greater than 0.05) when comparing the need for subsequent reoperation in each group. Operative mortality following open radical mitral commissurotomy (0%; 0 out of 150) was significantly less (p less than 0.05) than after mitral valve replacement in both porcine (8.1%; 6 out of 74) and Starr-Edwards (11.2%; 21 out out 187) groups. Life-table analysis of late cardiac-related mortality revealed a significantly greater cumulative survival rate for the commissurotomy versus the Starr-Edwards groups at all intervals from 12 to 108 months (100 versus 84 +/- 5%, p less than 0.05). No significant differences were noted between commissurotomy and porcine valve groups during the 4-year follow-up period (100 +/- 0% versus 96 +/- 3%, p greater than 0.05). Based on these findings, we conclude that when the anatomy is favorable, the surgical treatment of choice for isolated mitral stenosis is open radical mitral commissurotomy.

Epidural-evoked potentials: A more specific indicator of spinal cord ischemia

The purpose of this experimental study was to examine the differences between peripheral nerve stimulation and direct spinal stimulation in generating cortical somatosensory-evoked potential (SEP) responses for monitoring spinal cord ischemia during thoracic aorta cross-clamping. Adult mongrel dogs (n = 6) were placed under general anesthesia and a left thoracotomy was performed. A conventional stimulating electrode was placed over the posterior tibial nerve (PN-SEP), and a special bipolar electrode was placed epidurally over the spinal cord at L1-2 (SC-SEP). The aorta was cross-clamped proximal to the left subclavian artery. Stimulations were alternately performed through both electrodes, and SEP responses were continuously monitored. The cross-clamp was released after one hour and the animal was observed for another hour prior to sacrifice. Excellent SEPs were obtained with six stimuli over 3 sec via the SC-SEP stimulus in contrast to the 200 stimulations over 90 sec required for the PN-SEP stimulus. Aortic cross-clamping resulted in a significantly longer mean time to loss of SEPs for SC-SEP (mean +/- SEM, 13.7 +/- 1.0 min for SC-SEP vs 11.3 +/- 0.7 min for PN-SEP, P less than 0.05). Likewise, unclamping of the aorta consistently resulted in a shorter mean time to return of SEPs for SC-SEP compared with PN-SEP. These data indicate that direct epidural stimulation for evoked cortical responses is a more sensitive means of determining the adequacy of posterior spinal cord blood flow as reflected by posterior spinal cord function.(ABSTRACT TRUNCATED AT 250 WORDS)

Strategy for treatment of acute evolving myocardial infarction with pulsatile left heart assist device. Can this modality increase survival and enhance myocardial salvage

This article describes the technique of left heart bypass in the treatment of both experimental and clinical acute myocardial infarction. A new technique of closed-chest percutaneous left heart bypass that can be used in patients with acute evolving myocardial infarction and cardiogenic shock is also described.

Increased release of cyclic adenosine monophosphate into jugular vein in response to isoproterenol administration

Catecholamine administration elevates plasma cyclic AMP (cAMP) levels but the source of the cAMP is unknown. To determine possible sources, plasma cAMP levels were determined in blood vessels across the head, liver, kidney and lung in anesthetized dogs infused with the beta-adrenergic agonist, isoproterenol. Only the head showed an increased release of cAMP into the blood. The kidneys removed cAMP from the blood while liver and lung showed no change. This in vivo demonstration of release of cAMP from the head represents contributions from brain and facial muscles and may be a useful approach to study brain involvement in the action of various hormones and drugs.