Peritoneal tissue-oxygen tension during a carbon dioxide pneumoperitoneum in a mouse laparoscopic model with controlled respiratory support

Abstract OBJECTIVE Nitric oxide (NO), one of the most powerful endogenous vasodilators, is thought to play a major role in the development of delayed vasospasm in patients with subarachnoid hemorrhage (SAH). However, the role of the production of cerebral NO in patients with SAH is not known. In other SAH studies, NO metabolites such as nitrite and nitrate have been demonstrated to be decreased in cerebrospinal fluid and in plasma. METHODS In this study, a microdialysis probe was used, along with a multiparameter sensor, to measure NO metabolites, brain tissue oxygen tension, brain tissue carbon dioxide tension, and pH in the cortex of patients with severe SAH who were at risk for developing secondary brain damage and vasospasm. NO metabolites, glucose, and lactate were analyzed in the dialysates to determine the time course of NO metabolite changes and to test the interrelationship between the analytes and clinical variables. RESULTS Brain tissue oxygen tension was strongly correlated to dialysate nitrate and nitrite (r2 = 0.326;P < 0.001); however, no correlation was noted between brain tissue oxygen tension and NO metabolites in cerebrospinal fluid (r2 = 0.018;P = 0.734). No significant correlation between NO production, brain tissue carbon dioxide tension, and dialysate glucose and lactate was observed. CONCLUSION Cerebral ischemia and compromised substrate delivery are often responsible for high morbidity rates and poor outcomes after SAH. The relationship between brain tissue oxygen and cerebral NO metabolites that we demonstrate suggests that substrate delivery and NO are linked in the pathophysiology of vasospasm after SAH.

Download Full-text

Effects of Temperature on Cerebral Tissue Oxygen Tension, Carbon Dioxide Tension, and pH during Transient Global Ischemia in Rabbits

Anesthesiology ◽

10.1097/00000542-199802000-00019 ◽

1998 ◽

Vol 88 (2) ◽

pp. 403-409 ◽

Cited By ~ 34

Author(s):

Andreas Bacher ◽

Jae Young Kwon ◽

Mark H. Zornow

Keyword(s):

Carbon Dioxide ◽

Cerebral Ischemia ◽

Oxygen Tension ◽

Random Sequence ◽

Carbon Dioxide Tension ◽

Tissue Oxygen Tension ◽

Global Cerebral Ischemia ◽

Moderate Hypothermia ◽

Tissue Oxygen ◽

Cerebral Tissue

Background A decrease in brain temperature (Tbrain) causes a decrease in the cerebral metabolic rate for oxygen (CMRO2) and provides potent neuroprotection against ischemic damage. In the present study, the effects of mild to moderate hypothermia on cerebral tissue oxygen tension (PO2 brain), carbon dioxide tension (PCO2 brain), and pH (pHbrain) were monitored during short episodes of global cerebral ischemia. Methods After approval by the Animal Care and Use Committee, 10 New Zealand white rabbits were anesthetized (1% halothane in air) and mechanical ventilation was adjusted to maintain the arterial carbon dioxide tension at 35 mmHg (alpha-stat). A sensor to measure PO2 brain, PCO2 brain, pHbrain, and Tbrain was inserted into the brain through a burr hole in the skull. Tbrain was adjusted to 38 degrees C, 34.4 degrees C, and 29.4 degrees C in a random sequence in each animal. PO2 brain, PCO2brain, and pHbrain (all variables are reported at the actual Tbrain) were recorded every 10 s during a 5-min baseline, 3 min of cerebral ischemia induced by inflation of a neck tourniquet, and 10 min of reperfusion at each level of Tbrain. Analysis of variance and Dunnett's test were used for statistical analysis. Data are presented as means +/- SD. Results During ischemia, PO2 brain decreased from 56 +/- 3 to 33 +/- 2 mmHg at 38 degrees C, from 58 +/- 3 to 32 +/- 3 mmHg at 34.4 degrees C, and from 51 +/- 2 to 32 +/- 2 mmHg at 29.4 degrees C (p = NS). PCO2 brain increased by 6.7 +/- 2 mmHg at 38 degrees C, by 5.1 +/- 1.4 mmHg at 34.4 degrees C, and by 2.3 +/- 0.8 mmHg at 29.4 degrees C. pHbrain inversely followed the trend of PCO2 brain. Conclusions The attenuated increase in PCO2 brain during hypothermic ischemia results from the reduced CMRO2. The similar decrease in PO2 brain at all temperature levels indicates that despite the reduction in CMRO2, PO2 brain is no better preserved during brief episodes of hypothermic ischemia than during normothermic ischemia.

Download Full-text

Mild Hypercapnia Increases Subcutaneous and Colonic Oxygen Tension in Patients Given 80% Inspired Oxygen during Abdominal Surgery

Anesthesiology ◽

10.1097/00000542-200605000-00009 ◽

2006 ◽

Vol 104 (5) ◽

pp. 944-949 ◽

Cited By ~ 39

Author(s):

Edith Fleischmann ◽

Friedrich Herbst ◽

André Kugener ◽

Barbara Kabon ◽

Monika Niedermayr ◽

...

Keyword(s):

Carbon Dioxide ◽

Oxygen Tension ◽

Subcutaneous Tissue ◽

Supplemental Oxygen ◽

Carbon Dioxide Tension ◽

Tissue Oxygen Tension ◽

Tissue Oxygen ◽

End Tidal Carbon Dioxide ◽

End Tidal ◽

Inspired Oxygen

Background Supplemental perioperative oxygen increases tissue oxygen tension and decreases incidence of wound infection in colorectal surgery patients. Mild intraoperative hypercapnia also increases subcutaneous tissue oxygen tension. However, the effect of hypercapnia in patients already receiving supplemental oxygen is unknown, as is the effect of mild hypercapnia on intestinal oxygenation in humans-although the intestines are presumably the tissue of interest for colon surgeries. The authors tested the hypothesis that mild intraoperative hypercapnia increases both subcutaneous tissue and intramural intestinal oxygen tension in patients given supplemental oxygen. Methods Patients undergoing elective colon resection were randomly assigned to normocapnia (n = 15, end-tidal carbon dioxide tension 35 mmHg) or mild hypercapnia (n = 15, end-tidal carbon dioxide tension 50 mmHg). Intraoperative inspired oxygen concentration was 80%. The authors measured subcutaneous tissue oxygen tension in the right upper arm and intramural oxygen tension in the left colon. Measurements were averaged over time within each patient and, subsequently, among patients. Data were compared with chi-square, unpaired t, or Mann-Whitney rank sum tests; P < 0.05 was significant. Results Morphometric characteristics and other possible confounding factors were similar in the groups. Intraoperative tissue oxygen tension in hypercapnic patients was significantly greater in the arm (mean +/- SD: 116 +/- 29 mmHg vs. 84 +/- 25 mmHg; P = 0.006) and colon (median [interquartile range]: 107 [81-129] vs. 53 [41-104] mmHg; P = 0.020). Conclusions During supplemental oxygen administration, mild intraoperative hypercapnia increased tissue oxygen tension in the arm and colon. Previous work suggests that improved tissue oxygenation will reduce infection risk via the proposed pathomechanism, although only an outcome study can confirm this.

Download Full-text