Impact of surgical stress on the haemodynamic profile of isoflurane-induced hypotension.
It has been suggested that stimulation of adrenoreceptors could be responsible for some of the haemodynamic effects of isoflurane. But there are no solid data demonstrating the role of sympatho-adrenal stimulation induced by pain during isoflurane administration. The impact of surgical stress on the haemodynamic profile of isoflurane-induced hypotension has been investigated in 28 patients (47-76 years), scheduled for total hip arthroplasty. After premedication with morphine hydrochloride (0.1 mg/kg), patients were randomly assigned to receive either no fentanyl (control group) or fentanyl (5 micrograms/kg before tracheal intubation, 5 micrograms/kg before skin incision, and 2 micrograms/kg each 15 min during the 1st hour). Isoflurane was given to maintain mean arterial blood pressure in the range 6.7-8 kPa in both groups. Haemodynamic data and blood samples for determination of plasma renin activity (PRA) and epinephrine (E) and norepinephrine (NE) levels were collected before and during hypotension. The fentanyl group and the control group differed significantly during hypotension: heart rate, cardiac index, oxygen consumption and E, NE and PRA were lower (P less than 0.01) in the fentanyl group than in control group. Fentanyl lowered the required concentration of isoflurane to achieve the same degree of hypotension (end-tidal concentration: 0.8 +/- 0.2% in the fentanyl group and 1.4 +/- 0.15% in the control group; P less than 0.001). Our results demonstrate that the cardiovascular effects of higher isoflurane concentrations in the absence of narcotic analgesia are counterbalanced by adrenergic stress stimulation of released epinephrine and norepinephrine. Among the likely reasons for catecholamine release during isoflurane administration, inadequate analgesia may be considered.
Bernard
J M
JM
Department of Anaesthesia, Hôtel-Dieu, Nantes, France.
Pinaud
M
M
Macquin-Mavier
I
I
Remi
J P
JP
Souron
R
R
Bainvel
J V
JV
D000368:Aged; D004837:Epinephrine / Q000097:blood; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007022:Hypotension / Q000097:blood / Q000139:chemically induced*; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D012083:Renin / Q000097:blood; D013312:Stress, Physiological / Q000503:physiopathology*; D013514:Surgical Procedures, Operative / Q000009:adverse effects*
D007530:Isoflurane; D012083:Renin; D009638:Norepinephrine; D004837:Epinephrine