Phenylephrine but not ephedrine reduces frontal lobe oxygenation following anesthesia-induced hypotension.
BACKGROUND
Vasopressor agents are used to correct anesthesia-induced hypotension. We describe the effect of phenylephrine and ephedrine on frontal lobe oxygenation (S(c)O(2)) following anesthesia-induced hypotension.


METHODS
Following induction of anesthesia by fentanyl (0.15 mg kg(-1)) and propofol (2.0 mg kg(-1)), 13 patients received phenylephrine (0.1 mg iv) and 12 patients received ephedrine (10 mg iv) to restore mean arterial pressure (MAP). Heart rate (HR), MAP, stroke volume (SV), cardiac output (CO), and frontal lobe oxygenation (S(c)O(2)) were registered.


RESULTS
Induction of anesthesia was followed by a decrease in MAP, HR, SV, and CO concomitant with an elevation in S(c)O(2). After administration of phenylephrine, MAP increased (51 +/- 12 to 81 +/- 13 mmHg; P < 0.001; mean +/- SD). However, a 14% (from 70 +/- 8% to 60 +/- 7%) reduction in S(c)O(2) (P < 0.05) followed with no change in CO (3.7 +/- 1.1 to 3.4 +/- 0.9 l min(-1)). The administration of ephedrine led to a similar increase in MAP (53 +/- 9 to 79 +/- 8 mmHg; P < 0.001), restored CO (3.2 +/- 1.2 to 5.0 +/- 1.3 l min(-1)), and preserved S(c)O(2).


CONCLUSIONS
The utilization of phenylephrine to correct hypotension induced by anesthesia has a negative impact on S(c)O(2) while ephedrine maintains frontal lobe oxygenation potentially related to an increase in CO.
Nissen
Peter
P
Department of Anesthesia, Rigshospitalet 2041, University of Copenhagen, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark. p.nissen@rh.regionh.dk
Brassard
Patrice
P
Jørgensen
Thomas B
TB
Secher
Niels H
NH
D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D004809:Ephedrine / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D005283:Fentanyl; D005625:Frontal Lobe / Q000098:blood supply / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007022:Hypotension / Q000139:chemically induced* / Q000188:drug therapy*; D007431:Intraoperative Complications / Q000139:chemically induced / Q000188:drug therapy; D008408:Mastectomy; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010101:Oxygen Consumption / Q000187:drug effects*; D016105:Parathyroidectomy; D010656:Phenylephrine / Q000008:administration & dosage* / Q000009:adverse effects; D015742:Propofol; D012039:Regional Blood Flow / Q000187:drug effects; D013965:Thyroidectomy; D014662:Vasoconstrictor Agents / Q000009:adverse effects / Q000627:therapeutic use*
D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D004809:Ephedrine; D005283:Fentanyl; D015742:Propofol