The Effects of Small Intravenous Doses of Midazolam on Explicit Recall and the Bispectral Index after Fetal Expulsion in a Cesarean Section under General Anesthesia / 대한마취과학회지

BACKGROUND: Explicit recall in a cesarean section under general anaesthesia can be a terrifying experience and may cause psychological sequelae. Administering low doses of midazolam, we investigated the changes of the bispectral index (BIS) and the occurrence of explicit recall of specific events after fetal expulsion in a cesarean section under general anesthesia. METHODS: The investigation was carried out on 30 ASA 1 or 2 parturients who underwent a cesarean section under general anesthesia. Anesthesia was maintained with 50% N2O in oxygen and 0.75% of isflurane. We randomly allocated parturients into a control group (n = 10), group A (n = 10), and B (n = 10). Neither midazolam nor any other drugs except oxytocin were administered in the control group. In the group A and B, midazolam 0.02 and 0.03 mg/kg respectively, were injected immediately after umbilical cord clamping. An isolated forearm test were done to all the parturients at 5, 10, and 20 minutes after fetal expulsion. We assessed the changes of the BIS at 1, 2, 3, 4, 5, 10, 15, and 20 minutes after fetal expulsion, at discontinuance of isoflurane administration and extubation. The wav file, "clench your left or right hand" was binaurally played, simultaneously with the isolated forearm test. The wav file, "one, two, three, four, five" was also binaurally played 15 minutes after fetal expulsion. We interviewed all the parturients the next day and assessed the occurrence of explicit recall. RESULTS: The BIS values after fetal expulsion in the control group and group A was maintanied above 60 and group B, below 60 (P < 0.05). The lowest median BIS value was 54.5 in the group A, 36.4 in the group B (P < 0.05). There were two parturients in the control group and in the group A, respectively, who showed explicit recall. The results of the isolated forearm test were negative for all groups. The extubation times and PAR scores failed to show significant differences among the three groups. CONCLUSIONS: The authors confirmed the occurrence of explicit recall for specific events after fetal expulsion. The BIS values after fetal expulsion could be maintained below 60 until the end of surgery,and explicit recall could be prevented when we injected midazolam 0.03 mg/kg immediately after fetal expulsion.

The Effect of Anesthesia with Propofol-N2O on Neonate and Maternal Awareness during Cesarean Section / 대한마취과학회지

BACKGROUND: In anesthesia for cesarean section, there is an increased incidence of maternal awareness because a light plane of general anesthesia is chosen for fetal safety and rapid recovery. Propofol may be the choice if smooth induction and rapid maternal recovery are desired. Authors tried to know that propofol has properties which suggest that it might be useful alternative to thiopental and enflurane. METHODS: Forty patients in ASA class I or II scheduled for cesarean section were allocated randomly to either propofol (n=20) (P) or thiopental-enflurane (n=20) (T-E) group. Anesthesia was induced with propofol 2 mg/kg IV and maintained by continuous infusion of propofol 8 mg/kg/hr in P group and was induced with thiopental 4 mg/kg IV and maintained by inhalation of 1 vol% enflurane in T-E group. All patients received vecuronium 0.1 mg/kg and 50% N2O-O2. Blood pressure, heart rate, Apgar score, umbilical arterial blood gas analysis and the incidence of maternal awareness using the isolated forearm technique (IFT) were evaluated. RESULTS: Diastolic pressure was decreased in P group than T-E group at 10 min after delivery. Heart rate was increased in P group than T-E group at immediate after extubation (p<0.05). For apgar score, umbilical artery gas analysis and maternal awareness there were not significant differences between two groups. CONCLUSIONS: In comparison with thiopental-enflurane, propofol infusion (8 mg/kg/hr) coupled with N2O was proved to be clinically satisfactory anesthesia for cesarean section with no adverse effects on both mother and neonate.

Awareness and Recall During Anesthesia with Propofol-N2O or Thiopental-Enflurane-N2O for Cesarean Section / 대한마취과학회지

BACKGROUND: Experience of awareness and recall during general anesthesia would be most distressing for patients. Especially for the cesarean section, medical team must consider both maternal awareness and fetal safety. Authors tried to know the possibility of propofol use as induction and maintenance agent of anesthesia for the cesarean section in respect of maternal awareness, recall and fetal safety. METHODS: Forty patients (ASA physical status 1, 2) were allocated randomly to either propofol (n=20) (P) or thiopental-enflurane (n=20) (T-E) group. We checked B.P, pulse rate, and the incidence of maternal awareness using the isolated forearm technique (IFT). The postoperative interview was conducted between 12~24h after operation. RESULTS: The incidence of maternal awareness signaled by flexing fingers in response to voice commands were significantly lower in the T-E group (20% after induction, no response during other times) than the P group (45% after induction, then 35%, 30%, after 5, 10 min delivery respectively). Seven patients had postoperative recall of introspective awareness in the P group but no patients in the T-E group. The 1 min Apgar score of the newborn were significantly lower in the P group than the T-E group but both groups were within normal range. CONCLUSIONS: Our date indicated that, in comparison with thiopental-enflurane, propofol infusion (6 mg/kg/h) were associated with a greater incidence of awareness during surgery and recall.

Effects of Intravenous Anesthetics on EEG Spectral Analysis during Cesarean Section / 대한마취과학회지

BACKGROUND: Anesthesia induces the spectral changes in EEG. Attempts to relate these spectral changes to adequacy of anesthesia have been hindered due to the complex waveforms of EEG. The objective of this investigation is to monitor the awareness of patients during cesarean section by means of EEG spectral analysis. METHODS: 20 patients for cesarean section aged from 24 to 39 and ASA class I or II, were maintained with O2(50%)-N2O(50%)-enflurane(0.8%). And they were administered with midazolam(0.07 mg/kg) in group I(n=6), fentanyl(1 microgram/kg) in group II(n=7), and fentanyl(2 microgram/kg) in group III(n=7) after birth. The density of each spectral band in EEG (delta 1-3.25 Hz, theta 3.5-7.75 Hz, alpha 8-12.15 Hz and beta 13-31.75Hz) was analyzed to derive total density, delta ratio and median power frequency. RESULTS: The spectral data demonstrated that the alpha rhythm was dominant in pre-induction period and beta rhythm was abundant both in the immediate post-induction period and after birth for all three groups. Delta ratio and median power frequency decreased after injection of midazolam and fentanyl in all three groups. None of patients could recall the memory about experience during cesarean section. CONCLUSIONS: These findings indicate that EEG spectral analysis is potentially useful to determine the changes of cerebroelectrical activity but difficult to monitor the awareness of patients during cesarean section.

The incidence of Awareness with Recall and Dreams during General Anesthesia / 대한마취과학회지

BACKGROUND: Experience of awareness with recall during general anesthesia can be most distressing for patients. The psychological sequelae of subsequent recall of intraoperative events have been highlighted recently, but the incidence of awareness with recall is uncertain. METHODS: Randomly selected 451 patients, who received elective operation under general anesthesia and were able to communicate with anesthesiologists and follow up for 5 days between December 1995 and February 1996 at Korea Cancer Center Hospital, were interviewed on the 2nd day after their operation. RESULTS: The incidence of explicit memory for events during general anesthesia has been estimated at 0.4% by interviewing patients postoperatively. Auditory perception and the sensation of paralysis were most frequently mentioned. 1.1% of patients had been dreaming during general anesthesia. CONCLUSIONS: Under the influence of anesthetic drugs, the brain is capable of limited processing of information and memory function. Everyone in the operating room must be mindful of conversations during the course of anesthesia and all patients should be given an opportunity to discuss any awareness in detail.