Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
Athough moderate hemodilution is well tolerated in elderly patients without known cardiac disease , the combination with controlled hypotension may cause impairment of splanchnic oxygenation . The gastric intramural pH measured by tonometric method has been noted as an index of assessing the adequacy of splanchnic oxygenation . This study was designed to clarify the effects of controlled hypotension with hemodilution on splanchnic oxygenation in elderly patients.
METHODS: After institutional approval and informed consent, 20 patients without cardiac diseases undergoing hip surgery were divided into two groups according to age. Group A (N=10) included patients aged less than 60yr (48 +/- 11yr, mean +/- SD, range 29-58yr) and group B (N=10) more than 65yr (71 +/- 6yr, 66-78yr). Anesthesia was maintained with N2O-O2-isoflurane. After induction of anesthesia, hemodilution was produced by drawing 800-1000ml of blood and replacing it with same amount of hydroxyethyl starch (hematocrit 23-24% in either group). Controlled hypotension (MAP at 55 mmHg for 80 min) was induced with prostaglandin E1. Measurements, including gastric intramural pH(pHi), arterial blood pH(pHa) and lactate (LC) were measured before hemodilution (TO), after hemodilution (T1), 80 min after starting hypotension (T2) and 60 min after recovery from hypotension (T3). Statistical significance (p<0.05) was determined using ANOVA and Student's t-test.
RESULTS: The values of pHa and LC showed no change in either group throughout the time course. The values of pHi showed significant decreases at T1, T2 and T3 in either group. (Table 1)
CONCLUSIONS: 1) Moderate hemodilution might impair splanchnic oxygenation in both adult and elderly patients. 2) The combination with controlled hypotension would not enhance the impairment, and that aging would not increase the risk of the impairment.
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