Alterations in Cerebrospinal Fluid PO2, PCO2, and pH Measurements during and after Experimental Thoracic Aortic Cross-Clamping

Intraoperative monitoring of cerebrospinal fluid gas tension and pH before and after surgical revascularization for moyamoya disease

Background

This study aimed to directly measure cerebrospinal fluid (CSF) gas tensions and pH before and after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis for moyamoya disease.

Methods

This study included 25 patients with moyamoya disease who underwent STA-MCA anastomosis combined with indirect bypass onto their 34 hemispheres. About 1 mL of CSF was collected before and after bypass procedures to measure CSF partial pressure of oxygen (PCSFO2), CSF partial pressure of carbon dioxide (PCSFCO2), and CSF pH with a blood gas analyzer. As the controls, the CSF was collected from 6 patients during surgery for an unruptured cerebral aneurysm. PCSFO2 and PCSFCO2 were expressed as the ratio to partial pressure of oxygen (PaO2) and partial pressure of carbon dioxide (PaCO2), respectively.

Results

PCSFO2/PaO2 was 0.79 ± 0.14 in moyamoya disease, being lower than 1.10 ± 0.09 in the controls (P < 0.0001). PCSFCO2/PaCO2 was 0.90 ± 0.10 in moyamoya disease, being higher than 0.84 ± 0.07 in the controls (P = 0.0261). PCSFO2/PaO2 was significantly lower in pediatric patients than in adult patients and in the hemispheres with reduced cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to acetazolamide than in those with normal CBF but reduced CVR. STA-MCA anastomosis significantly increased PCSFO2/PaO2 from 0.79 ± 0.14 to 0.86 ± 0.14 (P < 0.01) and reduced PCSFCO2/PaCO2 from 0.90 ± 0.10 to 0.69 ± 0.16 (P < 0.0001). There was no difference in CSF pH between moyamoya disease and the controls.

Conclusion

PCSFO2/PaO2 was significantly lower in moyamoya disease than in the controls. Its magnitude was more pronounced in pediatric patients than in adult patients and depends on the severity of cerebral ischemia. STA-MCA anastomosis carries dramatic effects on CSF gas tensions in moyamoya patients. CSF may be a valuable biomarker to monitor the pathophysiology of cerebral ischemia/hypoxia in moyamoya disease.

Effects of superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis on the cerebrospinal fluid gas tensions and pH in hemodynamically compromised patients

PURPOSE

This study was aimed to directly measure cerebrospinal fluid (CSF) gas tensions and pH before and after STA-MCA anastomosis for occlusive carotid artery diseases to investigate its direct effects on the ischemic brain.

METHODS

This study included 9 patients who underwent STA-MCA anastomosis on the basis of CBF studies. About 1 mL of CSF was collected before and after bypass procedures, and CSF pH, CSF PO2, and CSF PCO2 were measured with a blood gas analyzer. As the controls, the CSF was collected from 6 patients during surgery for unruptured cerebral aneurysm. CSF PO2 and CSF PCO2 were expressed as the ratio to PaO2 and PaCO2, respectively.

RESULTS

Before bypass procedure, CSF PO2/PaO2 was 0.88 ± 0.16, being lower than the controls (1.10 ± 0.09; P = 0.005). CSF PCO2/PaCO2 was 0.93 ± 0.13, being higher than the controls (0.84 ± 0.06; P = 0.039). Ipsilateral-to-contralateral CBF ratio had a positive correlation with CSF PO2/PaO2 (P = 0.0028) but a negative correlation with the CSF PCO2/PaCO2 (P = 0.0045). STA-MCA anastomosis increased CSF pH from 7.402 ± 0.133 to 7.504 ± 0.126 (P = 0.0011) and CSF PO2/PaO2 from 0.88 ± 0.16 to 1.05 ± 0.26 (P = 0.018) but decreased CSF PCO2/PaCO2 from 0.93 ± 0.13 to 0.70 ± 0.17 (P = 0.0006).

CONCLUSION

The severity of cerebral ischemia before surgery is intensely reflected in the gas tensions and pH of the CSF. STA-MCA anastomosis carries dramatic effects on CSF gas tensions and pH in hemodynamically compromised patients. CSF would be a valuable surrogate biomarker to monitor the severity of cerebral ischemia.

Two episodes of remote ischemia preconditioning improve motor and sensory function of hind limbs after spinal cord ischemic injury

Objectives: To investigate the effect of one and two remote ischemia preconditioning episodes (1-RIPC or 2-RIPC, respectively) on neuro-protection after spinal cord ischemic injury (SCI) in rats. Design: Experimental animal study. Setting: College of Medicine, King Khalid University, Abha, KSA. Interventions: Male rats (n = 10/group) were divided into control, sham, SCIRI, 1-RIPC + SCIRI, and 2-RIPC + SCIRI. SCI was induced by aortic ligation for 45 min and each RIPC episode was induced by 3 cycles of 10 min ischemia/10 min perfusion. The two preconditioning procedures were separated by 24 h. Outcome measures: after 48 h of RIPC procedure, Tarlov's test, withdrawal from the painful stimulus and placing/stepping reflex (SPR) were used to evaluate the hind limbs neurological function. SC homogenates were used to measure various biochemical parameters. Results: Motor and sensory function of hind limbs were significantly improved and levels of MDA, AOPPs, PGE2, TNF-α, and IL-6, as well as the activity of SOD, was significantly decreased in SC tissue in either 1 or 2 episodes of RIPC intervention. Concomitantly, levels of total nitrate/nitrite and eNOS activity were significantly increased in both groups. Interestingly, except for activity of SOD, eNOS and levels of nitrate/nitrite, the improvements in all neurological biochemical endpoint were more profound in 2-RIPC + SCIRI compared with 1-RIPC + SCIRI. Conclusion: applying two preconditioning episodes of 3 cycles of 10 min ischemia/10 min perfusion, separated by 24 h, boost the neuro-protection effect of RIPC maneuver in rats after ischemic induced SCI in rats.

Intraoperative Changes in Cerebrospinal Fluid Gas Tensions Reflect Paraplegia During Thoracoabdominal Aortic Surgery

Background:

In this study, gas tensions in cerebrospinal fluid (CSF) were prospectively evaluated as intraoperative markers for the detection of neurological deficits.

Methods:

Spinal fluid, serum, and heart lung machine (HLM) perfusate were monitored for gas tensions (po2/pCo2) and related parameters (pH, lactate, and glucose) during thoracoabdominal aortic repair and correlated with perioperative neurological examination and electrophysiological testing.

Results:

Forty-seven patients were assessed for the study, and 40 consecutive patients were finally included. The patients were divided into 3 groups: group A (23 patients, 57.5%): no clinical or laboratory signs of neurological damage; group B (14 patients, 35%) who developed subclinical deficits; and group C (3 patients, 7.5%) who had paraplegia. Significant intraoperative changes in CSF gas tensions were observed with postoperative paraplegia. Glucose ratio between serum and CSF showed higher variability in group C, confirming a damage of the blood–brain barrier (BBB).

Conclusion:

Major neurological damage is reflected by early changes in CSF gas tensions and glucose variability, suggesting damage of the BBB in these patients.

Which type of conditioning method protects the spinal cord from the ischemia–reperfusion injury in 24 hours?

Objective

This study was designed to test the effects of different types of preconditioning and postconditioning methods on spinal cord protection following aortic clamping.

Methods

The animals (rabbits) were divided into sham-operated, ischemic preconditioning, remote ischemic preconditioning, simultaneous aortic and ischemic remote preconditioning, and ischemic postconditioning groups. After neurological evaluations, ultrastructural analysis and immunohistochemical staining for caspase-3 were evaluated after 24 h following ischemia.

Results

The neurological outcomes of the remote ischemic preconditioning (4.2 ± 0.4) and ischemic postconditioning (4.6 ± 0.8) groups were significantly improved when compared with the ischemia group (2.2 ± 04). The immunohistochemical analysis revealed that the lowest percentage of apoptosis was in-group ischemic preconditioning at 12.5 ± 30.6%. In the comparison of intracellular edema in an ultrastructural analysis, the ischemic preconditioning and ischemic postconditioning groups had significantly lower values than the ischemia group.

Conclusion

The conditioning methods attenuate ischemia–reperfusion injury for spinal cord injury. Ischemic and remote preconditioning and also postconditioning methods are simple to perform and inexpensive.

Ischemic preconditioning ameliorates spinal cord ischemia-reperfusion injury by triggering autoregulation

OBJECTIVE

The mechanism underlying ischemic preconditioning (IPC) protection against spinal cord ischemia-reperfusion (I/R) injury is unclear. We investigated the role of spinal cord autoregulation in tolerance to spinal cord I/R injury induced by IPC in a rat model.

METHODS

Sprague-Dawley rats were randomly assigned to four groups. IPC (P) group animals received IPC by temporary thoracic aortic occlusion (AO) with a 2F Fogarty arterial embolectomy catheter (Baxter Healthcare, Irvine, Calif) for 3 minutes. The I/R injury (I/R) group animals were treated with blood withdrawal and temporary AO for 12 minutes, and shed blood reinfusion at the end of the procedures. The P+I/R animals received IPC, followed by 5 minutes reperfusion, and then I/R procedures for 12 minutes. Sham (S) group animals received anesthesia and underwent surgical preparation, but without preconditioning or I/R injury. Neurologic function on postprocedure days 1, 3, 5, and 7 was evaluated by Tarlov scoring. Lumbar segments were harvested for histopathologic examination on day 7. To evaluate the role of autoregulation in IPC, spinal cord blood flow and tissue oxygenation were continuously monitored throughout the procedure duration.

RESULTS

The Tarlov scores in the I/R group were significantly lower than those in the S, P, and P+I/R groups on days 1, 3, 5, and 7 (P < .001). No significant differences were noted between the S, P, and P+I/R groups. The numbers of surviving motor neurons in the S, P, and P+I/R groups were significantly higher than those in the I/R group (P < .001); however, the number of surviving motor neurons did not differ between the S, P, and P+I/R groups. The P group exhibited higher spinal cord blood flow (P = .001-.043) and tissue oxygenation (P = .032-.043) within the first 60 minutes after reperfusion than the S group. The P+I/R group exhibited higher spinal cord blood flow (P = .016-.045) and tissue oxygenation (P = .001-.038) within the first 60 minutes after reperfusion than the I/R group.

CONCLUSIONS

IPC ameliorates spinal cord I/R injury in rats, probably mediated by triggering spinal cord autoregulation and improving local spinal cord blood flow and tissue oxygenation. This concept may be the new therapeutic targets in patients requiring aortic surgery.