DOI: 10.1097/01.aoa.0000370548.91575.53

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Issn Print: 0275-665X

Publication Date: 2010/06/01


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Effects of Remifentanil on Cardiovascular and Bispectral Index Responses to Endotracheal Intubation in Severe Preeclamptic Patients Undergoing Cesarean Delivery Under General Anesthesia

K.Y. Yoo; C.W. Jeong; B.Y. Park; S.J. Kim; S.T. Jeong; M.H. Shin; J. Lee

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Excerpt

Laryngoscopy and tracheal intubation can cause detrimental hemodynamic changes and arousal responses during induction of anesthesia. These responses may be exaggerated in pregnant women with gestational hypertension or preeclampsia. Increases of maternal plasma catecholamine concentration at anesthetic induction during cesarean section (CS) may also decrease uterine blood flow and adversely affect the neonate. Close control of stress responses in these scenarios may be necessary for both maternal and fetal well-being. Opioids have been used to attenuate hemodynamic and catecholamine responses during tracheal intubation. Remifentanil may be an ideal choice because of its quick onset and short half-life, which may reduce the risk of neonatal respiratory depression after CS. However, its use may be limited in preeclamptic patients. This study examined the effects of remifentanil on the maternal hemodynamic and arousal responses to intubation in severely preeclamptic women undergoing CS, and its effects on the neonate.
Forty-two preeclamptic, otherwise healthy, women with singleton fetuses who were undergoing elective or urgent CS with general anesthesia were enrolled in the study. In addition to routine monitoring, a bispectral (BIS) monitor was placed before induction to continually measure the arousal response associated with noxious stimulation. Patients were randomized into 2 groups of 21 each to receive either a bolus of 1 μg/kg of remifentanil or 0.9% saline (controls) over 30 seconds just before anesthesia was induced by rapid-sequence induction with intravenous sodium thiopentone 4 mg/kg and suxamethonium 1.5 mg/kg. Cricoid pressure was applied with loss of consciousness, and tracheal intubation was performed under direct laryngoscopy. BIS values, mean arterial pressure (MAP), and heart rate were recorded before injection of the study drug, before tracheal intubation, and at 1-minute intervals after intubation for 7 minutes. Maternal blood samples were drawn before induction, 1 minute after onset of intubation, and at delivery for measurement of plasma catecholamine concentrations.
Groups were similar in maternal characteristics, gestational age, and surgical characteristics. MAP and BIS decreased significantly in both groups after induction. MAP and heart rate increased in both groups after intubation; however, in the remifentanil group the increases were significantly smaller than in controls (P<0.001). Baseline BIS values were similar, decreasing after induction and increasing after intubation. Maternal baseline norepinephrine and epinephrine concentrations did not differ between groups, but norepinephrine concentrations increased significantly among controls after intubation, but remained unaltered in the remifentanil group (P<0.01). Apgar scores were significantly lower in the remifentanil group at 1 minute (P<0.05), although at 5 minutes they were similar, as were neonatal umbilical artery and vein blood gas values. Most neonates in both groups were preterm and admitted to the neonatal intensive care units. More babies of remifentanil-treated mothers needed resuscitative measures immediately after birth (P=0.04), but no neonates showed evidence of prolonged neurologic damage. There were no episodes of neonatal respiratory depression in either group after initial resuscitation, although 1 infant in each group required intubation in the neonatal intensive care unit.
These results showed that a single bolus of remifentanil 1 ug/kg effectively attenuated hemodynamic responses and catecholamine concentrations, but not BIS responses, to laryngoscopy and tracheal intubation in severely preeclamptic women undergoing CS. Transient respiratory depression in a significant number of neonates did occur, however, in the remifentanil group. The authors concluded that remifentanil is a useful adjunct during rapid sequence induction in severely preeclamptic women, but adequate facilities for neonatal respiratory resuscitation should be available if the drug is used.

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