Key result
Moderate haemodilution under isoflurane lowers gastric intramucosal pH without further drop from hypotension.
Why the study?
The effects of controlled hypotension with haemodilution under isoflurane anaesthesia on splanchnic perfusion in elderly patients were not well characterized.
Does controlled hypotension with haemodilution under isoflurane anaesthesia impair splanchnic perfusion in elderly patients compared to younger adults?
Does controlled hypotension with haemodilution under isoflurane anaesthesia impair splanchnic perfusion in elderly patients compared to younger adults?
p-value: p=<0.05
Moderate haemodilution under isoflurane anaesthesia impairs splanchnic perfusion, but the addition of controlled hypotension with PGE1 or advanced age does not cause further impairment.
Moderate haemodilution may impair splanchnic perfusion under isoflurane; leaves open whether controlled hypotension or age adds further risk.
We investigated the effects of controlled hypotension with haemodilution under isoflurane anaesthesia on splanchnic perfusion in elderly patients. We determined the intramucosal pH using gastric tonometry in 28 patients scheduled for hip surgery. Patients without cardiac disease were assigned to two groups according to age. Group A (adult patients, n=14) included patients aged less than 60 years (range 29-58 years, 47 ± 11 years, mean ± SD) and group B (elderly patients, n=14) more than 65 years (68-78 years, 72±5 years). Anaesthesia was maintained with N2O-O2-isoflurane. After induction of anaesthesia, haemodilution was produced by drawing 800-1000 mL of blood and replacing it with the same amount of hydroxyethyl starch. Final haematocrit values were 23-24% in all groups. Controlled hypotension was induced with prostaglandin E1 (PGE1) and mean blood pressure was maintained at approximately 60 mmHg for approximately 80 min. Measurements, including gastric intramucosal pH (pHi), arterial blood pH (pHa) and serum lactate were measured before haemodilution (T0), after haemodilution (T1), 80 min after starting hypotension (T2), 60 min after recovery from hypotension (T3) and on the 1st post-operative day (T4). The values of pHa and lactate showed no change in the groups throughout the time course. The gastric pHi values showed significant decreases from 7.418±0.035 to 7.334±0.024 (P<0.05) in group A and from 7.428±0.029 to 7.320±0.039 (P<0.05) in group B after haemodilution, while no further decreases were found at 80 min after starting the hypotension (7.329±0.038 in group A and 7.322±0.031 in group B) and 60 min after recovery from hypotension (7.331±0.029 in group A and 7.328±0.034 in group B). It can be concluded that moderate haemodilution under isoflurane anaesthesia might impair splanchnic perfusion in adult and elderly patients. The addition of controlled hypotension with PGE1 or an increase in age did not further impair splanchnic perfusion nor the splanchnic oxygen supply.
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Fukusaki et al. (1999) studied Scheduled for hip surgery (n=28). Controlled hypotension with haemodilution under isoflurane anaesthesia vs. Baseline (before haemodilution) was evaluated on Gastric intramucosal pH (pHi) (p=<0.05). Moderate haemodilution under isoflurane anaesthesia significantly decreased gastric intramucosal pH in adult and elderly patients (P<0.05), with no further impairment from controlled hypotension.
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