Ephedrine spinal anesthesia

Chinese medical practitioners in the 15th century recommended ephedra as an antipyretic and antitussive agent. Modem physicians use intravenous ephedrine for the prophylaxis and treatment of hypotension caused by spinal anesthesia, particularly during cesarean section (see Chapter 29). 

The disadvantages of spinal anesthesia are hypotension (ephedrine and methoxamine may prevent this), nausea and vomiting (avoided by thiopental), respiratory depression (treated by artificial respiration), and postoperative headache (treated by increasing the CSF pressure). 

Two apparently healthy women, aged 26 and 34 years, who were given spinal anesthesia for pelvic or hip surgery, both developed hypotension and bradycardia and were given intravenous ephedrine in divided doses, in... 

A 44-year-old woman was given ephedrine intravenously, to manage hypotension during spinal anesthesia. She developed intracranial hypertension and focal cerebral deficits related to multiple hemorrhagic cerebral infarcts. Angiography showed reversible beading, consistent with cerebral arteritis. 

A 68-year-old man developed total spinal anesthesia after the administration of 20 ml of ropivacaine 1% without a prior test dose via an epidural catheter, which was inadvertently placed intrathecally (83). Initial aspiration of both the Touhy needle and the catheter failed to identify the intrathecal position of the catheter. The patient noted weakness in his right leg immediately after the end of the injection. This was followed by weakness in his right arm, asystole, apnea, and loss of consciousness. Ventricular escape beats were noted and sinus rhythm returned after mask ventilation with 100% oxygen and the administration of atropine 1 mg and ephedrine 50 mg. He was able to open his eyes, but remained apneic and was therefore intubated and ventilated. Cardiovascular stabihty was maintained with incremental boluses of ephedrine to a total of 60 mg. He regained consciousness and was successfully extubated 145 minutes later. AH sensory and motor deficits had resolved within 8 hours and no neurological deficit or transient neurological symptoms were detected 5 days later. 

Intrathecal blockade with 0.5% isobaric bupivacaine 10 mg has been compared with 0.5% isobaric bupivacaine 5 mg combined with fentanyl 25 micrograms (diluted to 2 ml with isotonic saline) in 32 patients undergoing elective cesarean section (177). The bupivacaine + fentanyl combination was associated with significantly less hypotension than bupivacaine alone (31 versus 94%) and a near 10-fold reduction in the mean ephedrine requirement (2.8 versus 23.8 mg). There were also significant differences in the incidence of nausea (31 versus 69%) and the median time to peak block (8 versus 10 minutes) with bupivacaine plus fentanyl. The authors advised further large-scale studies to quantify the minimum dose of bupivacaine plus fentanyl for single-dose spinal anesthesia. 

Physicians routinely used intravenous ephedrine for the prophylaxis and treatment of hypotension caused by spinal anesthesia particularly during caesarean section (9). In the past, ephedrine was used to treat Stokes-Adams attacks (complete heart block), and was also recommended as a treatment for narcolepsy. Over the years, ephedrine has been replaced by other, more effective agents (10), and the advent of highly selective [3-agonists has mostly eliminated the need to use ephedrine in treating asthma. 

Hirabayashi Y, Saitoh K, Fukuda H, Mitsuhata H, Shimizu R. Coronary artery spasm after ephedrine in a patient with high spinal anesthesia. Anesthesiology 1996 84(1) 221—224. 

In the past, ephedrine was used to treat Stokes-Adams attacks with complete heart block and as a CNS stimulant in narcolepsy and depressive states. It has been replaced by alternate treatments in each of these disorders. In addition, its use as a bronchodilator in patients with asthma has become much less extensive with the development of p2-selective agonists. Ephedrine has been used to promote urinary continence, although its efficacy is not clear. Indeed, the drug may cause urinary retention, particularly in men with benign prostatic hyperplasia. Ephedrine also has been used to treat the hypotension that may occur with spinal anesthesia. 

Ephedrine may be used with success in combating the fall of blood pressure in spinal anesthesia, in the treatment of bronchial asthma (bronchodilatation), hay fever, and other allergic conditions. It relieves whooping cough. Ephedrine has been used both for the prevention and the cure of attacks of heart block known as Stokes-Adam s syndrome. Use of ephedrine in the prevention of the pathological sleep of narcolepsy is now replaced by its more efficient chemical relative, deoxynorephedrine (Benzedrine). Ephedrine is of value in the treatment of myasthenia... 

Intramuscular vasopressors were evaluated in 108 patients undergoing elective cesarean section under spinal anesthesia in a randomized, double-blind, placebo-controlled comparison of phenylephrine 2 or 4 mg and ephedrine 45 mg, all given immediately after induction of spinal anesthesia [28 ]. Hypotension was defined as a 25% reduction in mean arterial pressure. Rescue intravenous boluses of ephedrine were given for hypotension, nausea, vomiting, or dizziness. Phenylephrine 4 mg was more effective in preventing hypotension than phenylephrine 2 mg or ephedrine and reduced mean arterial pressure more than phenylephrine 2 mg. 

In 43 term parturients who were randomized to a bolus dose of ephedrine 10 mg with or without phenylephrine 40 micrograms during spinal anesthesia, the incidences of hypotension, defined as a systolic blood pressure below lOOmmHg or a fall of 20% from baseline, were 80% versus 95%, but the difference was not significant [3CF]. The authors concluded that adding phenylephrine to ephedrine did not improve the effect of ephedrine alone in preventing or treating hypotension in these cases. 

In 125 parturients who underwent cesarean delivery with spinal anesthesia, who were randomized to an intravenous infusion of phenylephrineephedrine in one of five different concentration ratios, the authors concluded that adding ephedrine to phenylephrine appeared to confer no advantage compared with phenylephrine alone [31 J. 

In a randomized, double-blind comparison of boluses of phenylephrine 100 micrograms and ephedrine 10 mg for hypotension (systolic blood pressure below lOOmmHg) in 204 patients undergoing cesarean section under spinal anesthesia, umbilical arterial and venous pH and base excess were similar in the two groups [32 ]. In those who received ephedrine umbilical arterial and venous lactate concentrations were slightly higher and more patients had nausea or vomiting (13% versus 3.9%). Clinical neonatal outcomes were similar. The authors concluded that phenylephrine and ephedrine are both suitable vasopressors for use in non-elective cesarean sections. 

In a randomized, double-blind, controlled comparison of bolus intravenous phenylephrine 100 micrograms and ephedrine 5 mg in maintaining arterial blood pressure during elective section under spinal anesthesia in 62 healthy parturients, both vasopressors restored the systolic and diastolic pressures the mean Apgar scores were similar in the two groups [37 "]. 

In 80 women who underwent cesarean section and were randomized to prophylactic phenylephrine (1.5 micrograms/kg plus a continuous infusion at 1.5 micrograms/kg/ minute) or ephedrine (0.1 mg/kg plus continuous infusion at a rate of 0.5 mg/kg/hour) immediately after spinal anesthesia, the overall incidence of hypotension was 11%, and there was no significant difference between the groups [39/f. However, phenylephrine was associated with more episodes of hypertension (28% versus 25%) and bradycardia (2.3% versus 0%). Umbilical cord blood parameters and Apgar scores were similar. After the end of the infusion there were episodes of hypotension in 72% of those who had received phenylephrine and 28% of those who had received ephedrine. 

In 90 women who underwent cesarean deliveries under spinal anesthesia, phenylephrine, phenylephrine + ephedrine, and ephedrine were used to maintain the blood pressure near baseline by adjusting the infusion rates [40 f. Fetal heart rates increased significantly after infusion of phenylephrine - -ephedrine and ephedrine alone but did not change after phenylephrine alone. After ephedrine, umbilical arterial and venous pH and base excess were lower than after phenylephrine alone and phenylephrine + ephedrine. Umbilical arterial PCO2 and plasma concentrations of lactate and glucose after ephedrine were greater than after phenylephrine. The authors concluded that phenylephrine may be better than ephedrine for treating the hypotension of spinal anesthesia for cesarean delivery. 

In 132 women who underwent cesarean section, intravenous phenylephrine, ephedrine, or phenylephrine + ephedrine were given immediately after spinal anesthesia and adjusted according to the systolic blood pressure [41 ]. There were more episodes of hypotension and tachycardia with ephedrine... 

Dose responsiveness In a study of the equivalently effective doses of ephedrine and phenylephrine in preventing hypotension after spinal anesthesia for cesarean section, the effective dosage ratio between ephedrine and phenylephrine was 80 1 (95% Cl =73, 90) the mean effective total doses were phenylephrine 500 micrograms and ephedrine 40 mg. 

Loughrey JP, Yao N, Datta S, Segal S, Pian-Smith M, Tsen LC. Hemodynamic effects of spinal anesthesia and simultaneous intravenous bolus of combined phenylephrine and ephedrine versus... 

Ngan Kee WD, Lee A, Khaw KS, Ng FF, Karmakar MK, Gin T. A randomized double-blinded comparison of phenylephrine and ephedrine infusion combinations to maintain blood pressure during spinal anesthesia for cesarean delivery the effects on fetal acid-base status and hemodynamic control. Anesth Analg 2008 107(4) 1295-302. 

Dyer RA, Reed AR, van Dyk D, Arcache MJ, Hodges O, Lombard CJ, Greenwood J, James MF. Hemodynamic effects of ephedrine, phenylephrine, and the coadministration of phenylephrine with oxytocin during spinal anesthesia for elective cesarean dehvery. Anesthesiology 2009 111(4) 753-65. 

Bhattarai B, Bhat SY, Upadya M. Comparison of bolus phenylephrine, ephedrine and mephentermine for maintenance of arterial pressure during spinal anesthesia in cesarean section. JNMA J Nepal Med Assoc 2010 49(177) 23-8. 

Lee A, Ngan Kee WD, Gin T. A quantitative, systematic review of randomized controlled trials of ephedrine versus phenylephrine for the management of hypotension during spinal anesthesia for cesarean delivery. Anesth Anaig 2002 94 (4) 920-6. 

Kol 10, Kaygusuz K, Gursoy S, Cetin A, Kahramanoglu Z, Ozkan F, Mimaroglu C (2009) The effects of intravenous ephedrine during spinal anesthesia for cesarean delivery a randomized controlled trial. J Korean Med Sci 24 883—888... 

A 31-year-old woman with no risk factors for cardiac disease had a perioperative myocardial infarction during spinal anesthesia, attributed to coronary artery vasospasm secondary to ephedrine and/or metaraminol [75 ]. 

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