Phenylephrine but not Ephedrine Reduces Frontal Lobe Oxygenation Following Anesthesia-Induced Hypotension

Abstract

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.

Propofol Compared to Etomidate Inductions and Attenuating Propofol Induced Hypotension

“…The control group had a hypotension incidence of 67.5%, while the ephedrine group that received 0.2 mg/kg showed 22.5% hypotension. Similar attenuation or complete prevention of hypotension were reported in eight other studies using ephedrine 0.1 mg/kg or 10-20 mg boluses [8][9][10]12,15,16]. El Tahan [6] also found that ephedrine improves ventricular contractility without causing relevant changes of left ventricular afterload.…”

“…Dosing of ephedrine varied from single bolus dosing to weight based dosing ranging from 10-15 mg to 0.07-0.2 mg/kg [6,[8][9][10][11][12][13][14][15][16]. Most trials had a timeframe for recording vitals ranging from 4-6 minutes with all trials showing similar results in this time frame.…”

Review article: The role of hypotension in perioperative stroke

“…59,60 Phenylephrine also decreased cerebral oxygen saturation, probably through a reduction in cardiac output, whereas ephedrine left it unchanged. 61,62 Maintaining normocapnea prevented this effect of phenylephrine. 63 Clinical studies in patients with neurological injuries, such as stroke, subarachnoid hemorrhage, and head trauma, do not uniformly support the benefits of raising blood pressure.…”

Cardiovascular Monitoring and Substitution of the Blood Volume During Liver Transplantation

“…Also it is to be considered that administration of phenylephrine in case of a low blood pressure, in an attempt to increase blood pressure to above what is might present the lower limit of cerebral autoregulation, is associated with a decrease rather than with the probably intended increase in S c O 2 (Nissen et al, 2010). Alternatively, hypotension should be considered in relation to a decrease in plasma calcium in response to administration of blood products and calcium should be supplemented to restore the physiological level (1.2 mM).…”

“…However, the use of phenylephrine may be indicated during reperfusion of the donor liver to reduce peripheral vasodilatation and thereby to centralise of blood accumulated in the splanchnic region. Alternatively, the administration of phenylephrine to increase the blood pressure may be replaced by the use of ephedrine that does not demonstrate the same negative influence on S c O 2 (Nissen et al, 2010;Meng et al, 2011). P a CO 2 has a significant influence on CBF and P a CO 2 is regularly monitored by a continuous recording of the end-tidal CO2 tension to maintain a value of, e.g.…”