Lennart Christiansson

Continuous monitoring of intrathecal pO2, pCO2 and pH during surgical replacement of type II thoracoabdominal aortic aneurysm

Continuous monitoring of intrathecal pO2, pCO2 and pH during surgical replacement of type II thoracoabdominal aortic aneurysm

Intraperitoneal and sigmoid colon tonometry in porcine hypoperfusion and endotoxin shock models.

Background: The objective of the present study was to assess the accuracy of an air tonometry device in vivo within a wide range of regional carbon dioxide tension (PrCO2) values by using saline tonometry as the standard and to investigate the possibilities to monitor perfusion of the intestine by tonometry in the intraperitoneal cavity.

Intraperitoneal tonometry for detection of regional enteric ischaemia.

Background: The objective of this study was to test the hypothesis that intraperitoneal tonometry can be a specific monitor for ischaemia in the small intestine.

Influence of segmental spinal cord perfusion on intrathecal oxygen tension during experimental thoracic aortic crossclamping

PURPOSE The purpose of this study was to evaluate the possibility of identifying alterations in blood supply to the spinal cord during thoracic aortic crossclamping. METHODS In 17 pigs, a multiparameter PO(2), PCO(2,) and pH sensor was introduced into the intrathecal space for continuous monitoring of cerebrospinal fluid (CSF) oxygenation during aortic crossclamping. An epidural laser Doppler probe was used to measure spinal cord flux. After insertion of an aortic shunt from the left subclavian to the left iliac artery and interruption of the right subclavian and lumbar arteries (L2-L5), the thoracic aorta just distal to the left subclavian artery was clamped for 60 minutes. By placement of the distal aortic crossclamping below the level of L1 in group A (n = 9 animals), perfusion of only the abdominal visceral arteries was maintained. In group B (n = 8 animals), the distal aortic crossclamping was above the level of T12, and thus some spinal cord perfusion was maintained through the aortic shunt. RESULTS The significant decrease in CSF PO(2) was observed within 3 minutes after the placement of the proximal aortic crossclamping and was normalized in all animals after establishment of the shunt flow. In group A, distal aortic crossclamping caused a decrease in CSF PO(2) with at least 50% of the preclamping values within 3 minutes. The mean CSF PO(2) of 2.99 +/- 0.70 kPa at 60 minutes of distal aortic crossclamping in group B was significantly higher than in group A (0.11 +/- 0.11 kPa; P <. 001). In group A, PCO(2) measurements showed no significant changes in 3 minutes after distal aortic crossclamping but revealed significantly higher values at 30 and 60 minutes compared with group B. Spinal cord flux values showed similar changes as CSF PO(2) during the whole experiment in both groups. CONCLUSION In this experimental model of aortic crossclamping, continuous CSF oxygen tension monitoring allows rapid detection of alterations in spinal cord circulation.

Increased FiO2 improves intrathecal oxygenation during thoracic aortic cross-clamping in pigs.

Objectives - To investigate the effect of 100% oxygen ventilation on cerebrospinal fluid (CSF) oxygenation in 11 pigs during thoracic aortic cross-clamping. Design - An aorto-aortic shunt was used for control of central hemodynamics and study of hypoperfusion by exsanguination. CSF PO2, PCO2 and pH were continuously monitored before and during clamping. The changes in hemodynamic parameters and intrathecal gas tensions in response to variations in proximal mean aortic pressure and fraction of inspired oxygen (FiO2) were recorded. Results - Baseline CSF PO2OBJECTIVES To investigate the effect of 100% oxygen ventilation on cerebrospinal fluid (CSF) oxygenation in 11 pigs during thoracic aortic cross-clamping. DESIGN An aorto-aortic shunt was used for control of central hemodynamics and study of hypoperfusion by exsanguination. CSF PO2, PCO2 and pH were continuously monitored before and during clamping. The changes in hemodynamic parameters and intrathecal gas tensions in response to variations in proximal mean aortic pressure and fraction of inspired oxygen (FiO2) were recorded. RESULTS Baseline CSF PO2 decreased from 4.8 +/- 1.9 to 2.6 +/- 2.2 kPa following aortic occlusion. Increasing FiO2 to 1.0 resulted in a significant increase in CSF PO2 to 4.1 +/- 3.0 with a return to 2.7 +/- 2.1 kPa after reducing FiO2 to 0.4 again. The same variations in FiO2 did not induce any significant changes in CSF PO2 during hypotension. CONCLUSION Increased FiO2 during experimental thoracic aortic cross-clamping with stable proximal arterial pressure helps to maintain CSF PO2, whereas severe hypotension could not be compensated for by hyperoxemia.

Anesthesia for Pheochromocytoma

Pheochromocytomas have an incidence of about 1–8 per million per year, and genetic studies have shown that approximately one third of patients have hereditary tumors or germ line mutations. The classical triad of presentation is paroxysmal sweating, hypertension, and headache. The activity of the sympathetic nervous system may be enhanced, and any trigger can potentially cause a malignant hypertensive crisis leading to fatal cerebrovascular accidents, dissecting aortic aneurysm, myocardial infarction, arrhythmia, and heart failure. The treatment of choice for adrenal tumors in general is surgical resection. Sustained norepinephrine release may lead to hypertrophic cardiomyopathy, a condition warranting tailored preoperative optimization. The events of greatest perioperative concern are anesthesia induction, insufflation of pneumoperitoneum, and tumor manipulation, but the mortality for scheduled pheochromocytoma resection is nowadays low.