European Journal of Cardio-Thoracic Surgery, Vol 7, 181-185, Copyright © 1993 by European Association for Cardio-thoracic Surgery
Myocardial uptake and release of lactate after high dose neurolept endotracheal intubation in coronary surgery
J Thorelius, O Wesslen, JA Bjorkman, R Ekroth, PO Joachimsson, G Ronquist and H Tyden
Department of Thoracic and Cardiovascular Surgery, University Hospital, Uppsala, Sweden.
To evaluate the relationship between the hemodynamic and ECG variables used
in routine surveillance of coronary surgery and myocardial lactate
metabolism, 23 middle-aged, male, beta 1-blocked patients about to undergo
coronary surgery were monitored before and after endotracheal intubation
with high dose (30 micrograms/kg) fentanyl-midazolam anesthesia. The
induction of anesthesia was followed by a mean arterial pressure decrease
(from 98 +/- 4 to 76 +/- 3 mm Hg) and heart rate increase (from 53 +/- 3 to
66 +/- 2 beats/min). After intubation the hemodynamic variables were stable
except for a further, transient increase in heart rate (to 69 +/- 2
beats/min). The myocardial uptake of lactate decreased after intubation,
from 48 +/- 5 mumol/min to a lowest level of 24 +/- 3 mumol/min. A lactate
release was exhibited in 7/23 patients (30%). No ST-segment changes were
observed. The correlation between the myocardial lactate uptake/release and
hemodynamic or ECG variables was unimpressive or non-existent (r < or =
0.20). Thus, a reduced uptake and even a release of lactate occurred
irrespective of the ST-segment, heart rate, or systemic or pulmonary artery
pressures. In conclusion, endotracheal intubation in patients with coronary
disease was consistently (17/23 patients) followed by a reduced myocardial
uptake of lactate, in spite of high dose neurolept anesthesia and beta
1-blockade. This metabolic event was not consistently related to
hemodynamic changes.
