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PubMed1993

Carotid artery revascularization following Crutchfield clamp placement. Report of two cases.

Several types of adjustable clamp have been widely utilized to gradually occlude the carotid artery for the treatment of various intracranial vascular lesions. A fairly large number of patients, many of whom have not been adequately followed, have these clamps still in place. The authors report two patients, initially treated with a Crutchfield clamp for an intracranial aneurysm, in whom carotid artery system revascularization occurred through the clamp many years later, leading to continued filling of the aneurysm. Recommendations are given on monitoring patients with Crutchfield clamps in order to minimize long-term complications.

Aged↗
PubMed1999

[Selective and unselective clamping in liver surgery].

Liver surgery requires a reduction in the operative blood loss to avoid postoperative liver failure. We carried out elective hepatic resection in 229 patients with Pringle's maneuver, which involves complete, intermittent clamping of the hepatic flow, and in 56 patients with selective vascular occlusion. Twenty-seven donors for living-related liver transplantation were also included in the latter series. The clinical outcomes were evaluated based on clamping method used. The cumulative clamping time and amount of blood loss were 64 +/- 46 min (mean +/- SD) and 828 +/- 665 ml in the Pringle's maneuver group and 88 +/- 44 min and 907 +/- 555 ml in the selective vascular occlusion group. Laboratory data showed good tolerance of vascular clamping in both groups, and serum aspartate aminotransferase levels returned to the baseline within one week. Operative morbidity rates were 23% and 27%, respectively, and no operative deaths occurred in this series. In living-related liver transplantation, modified selective vascular occlusion can preserve graft viability, as verified by the fact that all the recipients in this series had a good postoperative course, except for one death and one graft loss. In conclusion, intermittent total or selective vascular clamping is indispensable procedure during hepatic resection.

Constriction↗
PubMed2001

Clinical studies with home glucose clamping.

OBJECTIVE: Self-blood glucose control is crucial to improving long term outcomes in diabetes. To facilitate this task, we offered patients access to a remote computer continuously online for data collection, dosing decision support, and medical monitoring. Imbedded algorithms for home glucose clamping were custom programmed for each patient. The objectives of the present work were to determine what proportion of patients chose to use such support and whether users benefited from the effort compared to non-users. RESEARCH DESIGN AND METHODS: A single central computer system was used. Algorithms for home glucose clamping were custom programmed for each patient by their physician who set glucose targets, clamping factors and safety constraints. The systems were voice-interactive and required the remote patient to handle only a touch-tone telephone. Patients were free to access the system each day to report self-measured blood glucose levels or hypoglycemia symptoms together with carbohydrate counting, planned exercise, stress, illness or other life-style events. Clinical experience was in patients followed for 12 months in samples derived from three health-care environments. RESULTS: Some 388 patients were offered access to the system. Sixty percent of patients (N=231) actively used the system. Among the 3 study centers, over 104,000 blood glucose measurements were received during the start-up year. Each call was processed instantly and automatically. Patients benefited from the 24 hours access. Those receiving algorithmic assistance for home glucose clamping adjusted daily therapy more effectively: prevalence of hyper-glycemia and hypo-glycemia fell ~ 2-fold (p<0.05) and glycated hemoglobin levels declined 1.3% (p<0.001). CONCLUSIONS: Physicians and patients benefited. Patients with diabetes may be receptive to computer assistance. Many can accomplish glucose clamping at home and meet targets set by their physicians for self-blood glucose control while reducing the incidence of diabetic crises. The centralized system adds no costs for the patients and empowers physicians to provide safer and superior diabetes care.

Algorithms↗
PubMedDate not supplied

Indications for posthepatectomy hepatic vein reconstruction from functional and morphological studies: clamping test and hepatic vein branch distribution determined by three-dimensional computed tomography.

BACKGROUND/AIMS: Indications for hepatic vein reconstruction for preserving remnant liver function after hepatectomy were assessed using the clamping test and the findings of preoperative 3D-CT (3-dimensional computed tomography). METHODOLOGY: Fifteen patients who underwent hepatectomy for malignant tumors in segment VII or VIII, or both, were examined with preoperative 3D-CT and an intraoperative clamping test. RESULTS: On the basis of changes in right hepatic venous pressure during clamping, we classified all patients into 3 types: the persistent elevation type (P-type, 8 patients), the no elevation type (N-type, 3 patients) and the transitory elevation type (T-type, 4 patients). Hepatic venous hemoglobin oxygen saturation (ShvO2) decreased significantly in the P type but hardly changed in the T and N types during the clamping test. Both the inferior right hepatic vein (IRV6) and the tributary of the middle hepatic vein draining segment V (MV5) were detected by preoperative 3D-CT in the T and N types. CONCLUSIONS: Assessments of hepatic vein branch distribution using preoperative 3D-CT served to predict the results of the hepatic vein clamping test. The results of preoperative 3D-CT were useful as indications for hepatic vein reconstruction.

Adult↗
PubMed1992

The impact of single cell voltage clamp on the understanding of the cardiac ventricular action potential.

In this article we review results obtained during the last decade by the single cell voltage clamp technique on cardiac ventricular myocytes, and we re-evaluate the major ionic currents underlying the cardiac action potential. Since its introduction into cardiac electrophysiology in the late seventies this technique has greatly contributed to our knowledge about the role of the transmembrane ionic currents in the heart. Recent findings gained with this method have confirmed that the inward sodium current is responsible not only for the fast depolarization, but, in part, also for the maintenance of the plateau phase of the action potential. The kinetics of the inward calcium current measured by the single cell voltage clamp technique proved to be much faster than was previously thought. In addition, two types of the inward calcium current with different physiological roles have recently been identified. The L-type calcium current plays an important part in maintaining the plateau phase of the action potential and may cause depolarization at less negative potentials. Although the physiological significance of the T-type calcium current is less clear, it appears to be involved in the pacemaker function of cardiac tissues. Single cell voltage clamp experiments have shown that the inward rectifier potassium current is not independent of time, as described earlier, but it helps to terminate the final phase of repolarization, and presumably controls the resting membrane potential. Recent studies with the single cell voltage clamp method have revealed that the delayed rectifier potassium current has, most probably, more than one component and is extensively modulated by neurotransmitters. Its main role is to initiate and terminate cardiac repolarization. This current is of particular importance in regulating rate-dependent repolarizations. The transient outward current, which rapidly activates and inactivates after depolarization, initiates early fast repolarization and may also take part in rate-dependent repolarization. The ionic carriers of this current are most likely potassium and chloride. The use of the single cell voltage clamp technique has led to the discovery of formerly unrecognized currents, like the ATP-dependent potassium current, the sodium activated potassium current and the chloride currents. The application of the new technique has made it possible to focus more attention on currents which were difficult to study previously, such as Na/K pump and Na/Ca exchanger currents.

Action Potentials↗
PubMed1992

[Pelvic clamps for controlling shock in posterior pelvic ring injuries. Application, biomechanical aspects and initial clinical results].

The antishock pelvic clamp provides direct reduction and compression of unstable posterior pelvic ring disruptions. This is effective in preventing excessive blood loss, which is common in these fractures. Comparable to a carpenter's C-clamp, this device is applied in less than 10 min and exerts transverse compression directly over the iliosacral region, reducing the displaced sacral fractures or SI joint diastasis. Early reduction closes the bleeding surfaces and restores the intrapelvic space, providing for earlier tamponade, further decreasing blood loss. The clamp does not interfere with a possible subsequent laparotomy or necessary diagnostic procedures. On 10 cadaveric pelvic specimens the bone yield under compression with the pelvic clamp ranged from 135 N to 685 N relative to the mechanical quality of the bone. This is sufficient to stabilize the posterior ring during further manipulation of the patient in the early phase. Details of the application technique and our clinical experience with the pelvic clamp in the first 17 patients are discussed.

Adolescent↗
PubMed2004

[Effect of aortic clamping on hemodynamics at reconstruction of the thoracoabdominal aorta].

This paper describes an experience with monitoring and computerized follow up of the hemodynamic status in 60 patients at and right after reconstruction of the thoracoabdominal aorta. In addition to the routine control, measurements were made of the pressure in the large vessels and cavities of the heart, duration of each heart contraction and CI. The following parameters were computed automatically: the status of the ventricles for each heart contraction, resistance of the greater end pulmonary circulation, elasticity of the arterial, venous, pulmonary arterial and pulmonary venous reservoirs, also for each cardiac cycle. At the generally accepted monitoring the hemodynamic responses to the surgeon's manipulations on the aorta appear smoothed or are not visualized at all. The control of each heart contraction reveals the responses to application of the clamp and its removal from the aorta, with their hemodynamic significance being not questionable. Aortic clamping and clamp removal from the aorta are associated with the generalized response of the regulatory systems of the body. The slow and thoroughly controlled aortic clamping and graded, controlled blood flow restoration due to clamp removal as well as the use of sodium nitroprusside (trimetafan or isofluran are preferable) allow to avoid an abrupt stroke load of the left ventricle of the heart and, respectively, the generalized response of the regulatory systems of the body.

Aortic Aneurysm, Abdominal↗
PubMedDate not supplied

Protective effect of methylprednisolone and of intermittent hepatic pedicle clamping during liver vascular inflow occlusion in the rat.

BACKGROUND/AIMS: One of the main causes of postoperative morbidity and mortality following major hepatic resection is hepatic ischemia deliberately designed to reduce intraoperative hemorrhage. This study assessed the effects of intermittent or continuous hepatic ischemia and reperfusion with or without methylprednisolone pretreatment in the rat. METHODOLOGY: One hundred and eighty rats were divided into 3 groups undergoing hepatic ischemia of 60, 90, and 120 minutes total duration. Each group of rats were subdivided to receive either a continuous Pringle maneuver, or 30 min or 15 min of intermittent liver pedicle clamping. Ten minutes before ischemia induction, 10 rats from each group were pretreated with intravenous 3 mg/100 g bw methylprednisolone. RESULTS: With continuous hepatic pedicle clamping the rat survival rates inversely correlated with the duration of ischemia (survival: 70%, 40%, and 20% with ischemia of 60, 90, and 120 min). Survival rates at 15-min and 30-min intermittent ischemia groups were significantly higher than in the continuous clamping group (p<0.05). Methylprednisolone pretreatment did not significantly increase survival but resulted as a significant reduction in liver enzyme release (AST, ALT), at 90 min (p<0.05) and at 120 min (p<0.05) in the continuously clamped groups. When ischemia lasted 120 min, methylprednisolone pretreatment was associated with higher preservation of ATP liver content (p<0.05). CONCLUSIONS: This study confirms that intermittent hepatic pedicle clamping significantly improves survival in rats undergoing hepatic vascular inflow occlusion with a decrease in transaminase release and greater maintenance of intrahepatic ATP after prolonged total ischemia when animals were pretreated with methylprednisolone.

Adenosine Triphosphate↗
PubMed2005

Intra-aortic filtration: capturing particulate emboli during aortic cross-clamping.

Particulate emboli are an important factor in the development of complications after cardiac surgery. The use of an intra-aortic filter during aortic declamping has proved safe and effective in reducing the incidence of embolic complications. Because aortic cross-clamping is also associated with the risk of embolism, we measured the release of particulate emboli at the time of aortic cross-clamping and at declamping. We deployed intra-aortic filters (Edwards EMBOL-X Slim Protection System) at 2 different times during 15 consecutive cardiac procedures with cardiopulmonary bypass. Filter A was inserted before aortic cross-clamping and left in place for a mean time of 3 minutes, and Filter B was inserted before aortic declamping for a mean of 17 minutes. An independent institution performed histopathologic examination. All filters captured particulate emboli, independent of the patients' degree of proximal aortic atherosclerotic disease. Macroscopy showed that Filter A captured more particles (mean, 70 +/- 2.6) in 7 of 15 patients (46.7%), Filter B captured more particles (mean, 6.7 +/- 2.6) in 5 of 15 patients (33.3%), and the filters captured the same number in 3 of 15 patients (20%). Microscopy showed that both filters captured fibrous atheroma or fibrous cap in 10 of 15 patients. We observed no complications related to the use of the filters. Aortic cross-clamping is associated with a high risk of embolism. We suggest that optimal protection against embolism during cardiac surgery can be achieved by applying intra-aortic filtration not only before aortic declamping but also before aortic cross-clamping.

Aged↗
PubMed2006

Initial experience with the enclose proximal aortic anastomosis device during off-pump coronary artery bypass: an alternative to aortic side clamping.

BACKGROUND: The utilization of off-pump coronary artery bypass surgery (OPCAB) has resulted in the development of new technology to facilitate the creation of aorto-coronary graft anastomoses. Proximal aortic devices (PADs) enable the construction of a proximal aortic anastomosis without the use of a side-biting aortic clamp, thus reducing the risk of neurologic injury from particulate embolization. METHODS: One hundred ninety-seven patients underwent OPCAB at our institution between January 2003 and December 2004. Sixty (30.5%) patients had proximal aorto-coronary graft anastomoses constructed with the Novare Enclose PAD. The remaining 137 (69.5%) patients had graft construction with a standard aortic side-clamp technique. We compared the outcomes of these 2 cohorts to evaluate the safety and efficacy of the Novare Enclose PAD. RESULTS: One hundred seven proximal anastomoses were constructed in the PAD group, and 199 proximal were constructed in the side-clamp group. Three patients (1.5%), all in the side-clamp group, sustained permanent neurologic deficits after OPCAB. There were 2 cases of device malfunctions. There were no anastomotic thromboses, no reoperations for anastomotic hemorrhage, and no patients required anastomotic revision. Of the 197 patients in the series, there were 4 deaths, 2 in each group, resulting in an overall mortality rate of 2%. CONCLUSION: The Novare Enclose PAD is a safe device that facilitates suture construction of proximal aorto-coronary graft anastomosis. In a select group of patients, the use of this device may reduce the risk of neurologic injury when compared to the application of an aortic side-biting clamp for coronary bypass surgery.

Aged↗
PubMed1987

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. II. Use of somatosensory evoked potentials to assess adequacy of distal aortic bypass and perfusion after thoracic aortic cross-clamping.

Pulsatile left atrial-femoral artery bypass was instituted after aortic cross-clamping distal to the left subclavian artery in a canine experimental model to determine the relationship of distal aortic perfusion pressure with spinal cord blood flow and somatosensory evoked potentials. In six animals (Group I) distal aortic perfusion pressure was maintained at 100 mm Hg throughout a 1 hour interval of aortic cross-clamping. During this period, somatosensory evoked potentials and spinal cord blood flow (radioactive microspheres) showed no significant change from baseline. In six other dogs (Group II) distal aortic perfusion pressure was initially maintained at 100 mm Hg after aortic cross-clamping and then progressively decreased to 70, 40, and 25 mm Hg. Somatosensory evoked potentials and spinal cord blood flow were preserved at baseline levels for all distal perfusion pressures greater than 70 mm Hg. At 40 mm Hg, abnormalities in amplitude of the somatosensory evoked potentials were noted in all animals with progression to complete loss of evoked potential activity at lower perfusion pressures. Maintenance of adequate somatosensory spinal cord conduction after thoracic aortic cross-clamping is dependent on a critical level of distal aortic perfusion that can be accomplished by use of an adjunct such as pulsatile left atrial-femoral artery bypass. The critical level of distal aortic perfusion pressure to maintain normal somatosensory evoked potentials and spinal cord blood flow in this canine experimental study was 70 mm Hg or greater. Because inadequate distal aortic perfusion can be easily detected by monitoring of somatosensory evoked potentials, these techniques should prove helpful in evaluating the effectiveness of distal perfusion techniques during clinical aortic cross-clamping for procedures on the thoracoabdominal aorta.

Animals↗
PubMed1986

The mechanism of spinal cord injury after simple and double aortic cross-clamping.

Ischemic spinal cord injury after cross-clamping of the descending aorta can occur independently of aortic disease. In a previous study we had shown a precipitous uniform fall of spinal surface oxygen tension downstream to the clamping site irrespective of level. In the present paper, the hemodynamic changes in the spinal and aortic collateral circulation were investigated. Pressures were measured in the proximal, distal, and excluded aortic segments (descending thoracic and lumbar aorta) as well as in the intercostal and the lumbar arterial beds. Before high aortic occlusion, pressures in the intercostal and lumbar arterial beds were lower than aortic pressure. Along with the postclamping fall in distal arterial pressure, intercostal and lumbar arterial bed pressure decreased further but remained above aortic pressure. Exclusion of the thoracic aorta by double clamping restored intercostal bed pressure almost to control, whereas exclusion of the abdominal aorta hardly affected lumbar bed pressure. We conclude that spinal collateral circulation is more highly developed in the thoracic than in the lumbar region. After aortic cross-clamping, blood tends to drain away from the spinal cord rather than supplying it longitudinally. Under clinical conditions, therefore, retrograde bleeding into the opened aorta as well as into the aorta downstream to the distal clamp should be minimized and larger vessels originating from the aorta should promptly be anastomosed to the graft.

Animals↗
PubMed1985

[Early or late cord clamping? A question of optimal time].

UNLABELLED: Late cord clamping allows a redistribution of placental blood to the fetus within 3 minutes. A sufficient difference in hydrostatic pressure between placenta and fetus is the prerequisite for placental transfusion. Placental transfusion is reduced or diminished if the newborn baby is positioned above the placenta. Blood volume and blood pressure of the fetus are elevated after placental transfusion. The increased blood volume correlates with the effective renal blood flow. There is no difference between cardiovascular parameters 6 hours post partum in infants subjected to early or late clamping of the cord. Nevertheless, erythrocyte volume and oxygen capacity remain high during the first days of life in infants with late cord clamping. CONCLUSION: In normal deliveries the cord should be clamped after 1 to 2 minutes. In premature infants, however, placental transfusion is advantageous because the incidence of respiratory distress syndrome is lower with late clamping. If the fetus is hypoxic in utero, redistribution of the blood and placental transfusion takes place already before birth to improve the oxygen supply to the fetal tissue and resuscitatory measures can be undertaken immediately following birth.

Blood Volume↗
PubMed1984

Intermittent aortic cross-clamping versus St. Thomas' Hospital cardioplegia in extensive aorta-coronary bypass grafting. A randomized clinical study.

Myocardial preservation was assessed in 72 patients undergoing extensive myocardial revascularization. The patients were allocated at random to three surgical techniques: Group 1, intermittent aortic cross-clamping at 32 degrees C; Group 2, intermittent aortic cross-clamping at 25 degrees C; and Group 3, St. Thomas' Hospital cardioplegia. As intraoperative markers of ischemic damage, adenosine triphosphate, creatine phosphate, and glycogen contents were determined in transmural left ventricular biopsy specimens taken at the beginning and at the end of cardiopulmonary bypass. Ultrastructure was studied in a similar pair of biopsy specimens. Release of myocardium-specific creatine kinase isoenzyme was determined intraoperatively and postoperatively. Functional recovery was assessed before and after weaning from cardiopulmonary bypass. The incidence of low cardiac output, myocardial infarction, and rhythm disturbances was compared between groups. Finally, actuarial survival and event-free curves were studied after 18 months' follow-up. The results show a better preservation of high-energy phosphates, glycogen, and ultrastructure in the cardioplegia group as compared to the two cross-clamp groups. However, severe myocardial damage was never observed. Release of MB creatine kinase isoenzyme was the same in all three groups. Functional recovery of the hearts immediately after cessation of cardiopulmonary bypass was better in the cardioplegia group, but the incidence of rhythm disturbances (atrioventricular conduction problems) was higher in the cardioplegia group than in the other two groups (p less than 0.05). Clinical outcome in terms of incidence of perioperative infarction, survival, and event-free follow-up was not different between groups. It is concluded that both techniques (aortic cross-clamping at 32 degrees C or 25 degrees C and St. Thomas' Hospital cardioplegia) offer good myocardial protection in extensive aorta-coronary bypass operations. St. Thomas' cardioplegia, however, in contrast to intermittent aortic cross-clamping, prevents the onset of ischemia-induced deterioration of cardiac metabolism, i.e., destruction of the adenine nucleotide pool.

Adenosine Triphosphate↗
PubMed1982

Development of the Biostator Glucose clamping algorithm.

The "glucose clamping" technique has been proposed as a method for the early detection of a beginning derangement of glucose homeostasis and thus for the possible prevention of maturity-onset diabetes. This technique interrupts the physiological glucose-insulin relationship by placing a patient's blood glucose concentration under an investigator's control, for quantification of the pancreatic beta-cell response during hyperglycemic clamps and of sensitivity of body tissue to exogenous insulin during normoglycemic clamps. We report the development of a glucose clamping algorithm for use with the Biostator glucose-controlled insulin-infusion system (Horm. Metab. Res., Suppl. 8: 23-33, 1977). This algorithm adds simplicity and precision to the glucose clamping procedure and reduces operator effort to a minimum. We describe the early development of the algorithm with a model system and report evaluations made during animal studies and preliminary investigations with human subjects.

Animals↗
PubMed1983

Regional blood flow during cross-clamping of the thoracic aorta and infusion of sodium nitroprusside.

Labeled microspheres, 15 microns in diameter, were used to determine cardiac output and regional blood flow response to cross-clamping of the midthoracic aorta and subsequent sodium nitroprusside (SNP) infusion in 11 dogs. During aortic cross-clamping, mean arterial pressure above the occlusion (MAPa) increased 30% to 35%, mean arterial pressure below the occlusion (MAPb) decreased 87%, cardiac index decreased 12% to 14%, left atrial pressure (LAP) doubled, and renal and spinal cord (lower part) blood flows decreased substantially (85% to 94%). SNP infusion returned MAPa to baseline values, decreased MAPb by half, and substantially and further decreased renal blood flow (to 3% to 5% of baseline values). Myocardial and cerebral blood flows increased substantially (up to 250% to 400%). An increase in preload (fluid load) was accompanied by an increase in LAP, cardiac index, and myocardial blood flow only but not in renal or spinal cord flow. There was a strong association between cortical renal blood flow and MAPb (r2 = 0.92; p less than 0.0001), which suggests that blood flow through organs and tissues below the occlusion is pressure dependent. The data show that SNP infusion during thoracic aortic cross-clamping improves systemic and regional circulation above the occlusion but decreases MAPb and therefore blood flow below the occlusion. SNP infusion should be used with caution during aortic cross-clamping, since arterial hypotension of any degree may be deleterious to organs below the cross-clamp.

Animals↗
PubMed1982

[Orthotopic liver graft with aortic clamping. Experimental study in dogs (author's transl)].

Orthotopic liver transplants were conducted in 15 dogs, with aortic clamping during the anhepatic time of the operation and without venous shunting. Aortic clamping lasted for between 30 and 42 minutes. Immunosuppressant treatment was not given. Eight dogs died within 2 hours after the operation, 5 from haemorrhage and 3 accidentally. Seven animals survived for between 6 hours and 11 days: 3 died within 24 hours from haemorrhage, 2 from hepatic failure between the 2nd and 3rd day. One animal died on the 7th day from an acute intestinal invagination, the dog surviving for the longest period eventually dying after rejection of the transplant. These results demonstrate, as in other reported series, that the most frequent cause of death is the haemorrhagic diathesis, probably as a result of poor graft conservation. Dogs tolerate the supracoeliac aorta clamp both from the renal and intestinal points of view ; spinal cord tolerance to the ischaemia is less evident as paraplegia of the hindquarters was noted in one animal in the group. Aortic clamping considerably reduces operative time, as it avoids the need to construct a mesentericocaval anastomosis and a femorojugular shunt. It also avoids splanchnic blood sequestration and the risk of reducing cardia filling during clamping of the inferior vena cava.

Animals↗
PubMed1994

Intrathecal magnesium sulfate protects the spinal cord from ischemic injury during thoracic aortic cross-clamping.

BACKGROUND: Paraplegia is a known complication after surgery on the descending thoracic aorta. Thoracic aortic cross-clamping causes an increase in proximal aortic and cerebrospinal fluid pressures. Sodium nitroprusside, though effectively decreasing proximal aortic pressure, has been implicated in worsening the incidence of paraplegia by further increasing cerebrospinal fluid pressure and decreasing distal blood pressure, thereby reducing spinal cord perfusion pressure. Intravenous administration of magnesium sulfate has been shown to offer some spinal cord protection when used with mild hypothermia. This study investigated the effect of intrathecal magnesium on the prevention of paraplegia when sodium nitroprusside is used to control proximal hypertension during thoracic aortic cross-clamping in a dog model of spinal cord ischemia. METHODS: Two groups of eight dogs underwent thoracic aortic cross-clamping via a small thoracotomy incision for 45 min. Proximal, distal, and central venous pressures and cerebrospinal fluid pressures were monitored. Temperature was maintained at 36 degrees C. Sodium nitroprusside was used to control proximal hypertension. The control group received no magnesium sulfate, and a second group received 3 mg/kg intrathecal magnesium sulfate before thoracic aortic cross-clamping. The dogs were neurologically evaluated 24 h later by an observer blinded to the dogs' group. Spinal cord segments were obtained for histologic examination. RESULTS: Proximal mean arterial pressure, cerebrospinal fluid pressure, spinal cord perfusion pressure, and central venous pressure were not statistically different between the two groups. Neurologic outcome, however, was statistically different between the groups. None of the eight dogs in the magnesium group had any measurable neurologic injury, in contrast to the control group, in which seven of the eight dogs had severe neurologic injury (P < 0.005). Post mortem histologic data supported these findings. CONCLUSIONS: Intrathecal magnesium can prevent spinal cord injury despite markedly negative spinal cord perfusion pressure during thoracic aortic cross-clamping in a canine model of spinal cord ischemia.

Animals↗