Intraoperative Awareness During General Anesthesia for Cesarean Delivery

The anesthetic approach to a patient with placenta accreta spectrum

PURPOSE OF REVIEW

Placenta accreta poses significant risk of morbidity and mortality to a laboring patient. Here we review available treatment options, highlight trends in bleeding prevention and diagnosis that have been shown to improve patient outcome, and provide best practice suggestions. We also discuss the decision-making process for choice of anesthesia, as it is not based on a gold-standard paradigm.

RECENT FINDINGS

The use of resuscitative endovascular balloon occlusion of the aorta has been gaining popularity around the world. It has been shown to cause an equivocal reduction in perioperative bleeding in placenta accreta spectrum (PAS), reduce the rate of hysterectomies, and is a safe and relatively easy technique. There are other invasive radiology techniques that have also proven to be beneficial in bleeding prevention: balloon occlusion of hypogastric arteries intraoperatively, internal iliac artery embolization, and intraoperative ligation of the hypogastric or uterine arteries.

SUMMARY

Optimal management of PAS begins with early and definitive diagnosis. A multidisciplinary approach along with preparation of special equipment and the use of a check-list maximize the chance for success. Anesthesia could be done with all types of regional or under general, considering case-by-case factors but most importantly choosing according to the institution's best facility and skill.

Prolonged Anesthesia Induction to Delivery Time Did Not Influence Plasma Remifentanil Concentration in Neonates

Objective

Remifentanil, in combination with etomidate and sevoflurane, is commonly used in clinics for general anesthesia induction in cesarean section (CS). This study aimed to evaluate the correlation between the induction to delivery (I-D) time and neonatal plasma drug concentration and anesthesia, as well as its effects on neonates.

Methods

Fifty-two parturients in whom general anesthesia was induced for CS were divided into group A (I-D<8 min) and group B (I-D≥8 min). Maternal arterial (MA), umbilical venous (UV), and umbilical arterial (UA) blood samples were collected at delivery to analyze the remifentanil and etomidate concentrations using liquid chromatography-tandem mass spectrometry.

Results

There were no statistically significant differences between the two groups in terms of plasma concentrations of remifentanil in the MA, UA, and UV blood (P > 0.05). The plasma concentration of etomidate in MA and UV was higher in group A than that in group B (P<0.05), whereas the UA/UV ratio of etomidate was higher in group B than that in group A (P<0.05). The Spearman rank correlation test showed no correlation between the I-D time and plasma remifentanil concentration in the MA, UA, and UV plasma (P>0.05). The concentrations of etomidate in the MA and UV were negatively correlated with the I-D time (P < 0.05).

Conclusion

Prolonged I-D time did not significantly influence the maternal or neonatal plasma concentration of remifentanil. It is safe to administer remifentanil target-controlled infusion in combination with etomidate and sevoflurane for general anesthesia induction during CS.

Intraoperative Awareness in Patients Undergoing Cardiac Surgery in an Academic Center in the North of Iran

Background

Coronary artery bypass grafting (CABG) has distinctive characteristics that may increase the risk of awareness during general anesthesia (AGA).

Objectives

This study was conducted to assess the incidence of AGA in cardiac surgery in an academic hospital in Guilan, Iran.

Methods

This descriptive cross-sectional study was performed in Dr. Heshmat Hospital in Rasht, Iran. Eligible patients candidates for CABG were enrolled in the survey in 2022. After surgery, when the patient was cooperative enough, a questionnaire including demographic data and specialized questions related to different stages of anesthesia was completed via face-to-face interviews. The data were analyzed using IBM SPSS Statistics 21 with chi-square, Fisher's exact, and t-test.

Results

The data from 322 patients were analyzed, of whom 14 (4.3%) experienced AGA. Among them, the "feeling of fear and anxiety" reported by 9 (39.1%) cases was the most common awareness state. "Dreaming during surgery and anesthesia" and "feeling unable to move during anesthesia,", each reported by 6 (26.1%) cases, were the other common types of awareness state. None of the demographic data had a significant association with the occurrence of AGA.

Conclusions

The incidence of AGA during CABG was almost acceptable according to the credible evidence.

The Current Role of General Anesthesia for Cesarean Delivery

PURPOSE OF THE REVIEW

The use of general anesthesia for cesarean delivery has declined in the last decades due to the widespread utilization of neuraxial techniques and the understanding that neuraxial anesthesia can be provided even in urgent circumstances. In fact, the role of general anesthesia for cesarean delivery has been revisited, because despite recent devices facilitating endotracheal intubation and clinical algorithms, guiding anesthesiologists facing challenging scenarios, risks, and complications of general anesthesia at the time of delivery for both mother and neonate(s) remain significant. In this review, we will discuss clinical scenarios and risk factors associated with general anesthesia for cesarean delivery and address reasons why anesthesiologists should apply strategies to minimize its use.

RECENT FINDINGS

Unnecessary general anesthesia for cesarean delivery is associated with maternal complications, including serious anesthesia-related complications, surgical site infection, and venous thromboembolic events. Racial and socioeconomic disparities and low-resource settings are major contributing factors in the use of general anesthesia for cesarean delivery, with both maternal and perinatal mortality increasing when general anesthesia is provided. In addition, more significant maternal pain and higher rates of postpartum depression requiring hospitalization are associated with general anesthesia for cesarean delivery.

SUMMARY

Rates of general anesthesia for cesarean delivery have overall decreased, and while general anesthesia no longer is a contributing factor to anesthesia-related maternal deaths, further opportunities to reduce its use should be emphasized. Raising awareness in identifying situations and patients at risk to help avoid unnecessary general anesthesia remains crucial.

Comparison of electroencephalogram between propofol- and thiopental-induced anesthesia for awareness risk in pregnant women

There have been few comparative studies using electroencephalogram (EEG) spectral characteristics during the induction of general anesthesia for cesarean section. This retrospective study investigated the differences in the depth of anesthesia through EEG analysis between propofol- and thiopental-induced anesthesia. We reviewed data of 42 patients undergoing cesarean section who received either thiopental (5 mg/kg) or propofol (2 mg/kg). EEG data were extracted from the bispectral index (BIS) monitor, and 10-second segments were selected from the following sections: 1) Stage I, BIS below 60 after induction; 2) Stage II, after intubation completion; 3) Stage III, end-tidal sevoflurane above 0 vol%. The risk of awareness was represented by the BIS and entropy measures. In Stage III, the thiopental group (n = 20) showed significantly higher BIS value than the propofol group (n = 22) (67.9 [18.66] vs 44.5 [20.63], respectively, p = 0.002). The thiopental group had decreased slow-delta oscillations and increased beta-oscillations as compared to the propofol group in Stages II and III (p < 0.05). BIS, spectral entropy, and Renyi permutation entropy were also higher in the thiopental group at Stages II and III (p < 0.05). In conclusion, frontal spectral EEG analysis demonstrated that propofol induction maintained a deeper anesthesia than thiopental in pregnant women.

[Selection of the optimal anesthesia regimen for cesarean section]

Approximately one third of all children in Germany are delivered by cesarean section. Depending on the individual patient's condition and the situation, the anesthesiologist has to choose between a general or a regional anesthesia regimen. The decisive factor for the selection is the obstetric urgency (decision-delivery time) after ascertainment of the indications. Furthermore, the need for postoperative analgesia varies depending on the chosen anesthesia regimen.

Monitoring the end-tidal concentration of sevoflurane for preventing awareness during anesthesia (MEETS-PANDA): A prospective clinical trial

OBJECTIVE

It was hypothesized that monitoring end-tidal sevoflurane (ETS) during endoscopic surgery could reduce the incidence of intraoperative awareness in patients undergoing general anesthesia. Herein, the incidence of intraoperative awareness and other correlative factors was recorded and compared.

METHODS

Two thousand five hundred ASA I-III patients aged 18-80 years who underwent general anesthesia were randomly divided into 2 groups (n = 1250): routine care group (R) and ETS concentration group (E). ETS concentration was monitored in group E and maintained at a sevoflurane minimum alveolar concentration (MAC) of 0.7-1.3; group R was monitored using routine care, and the sevoflurane was maintained. Patients were assessed for intraoperative awareness with a questionnaire on their explicit memory 24-48 h after surgery.

RESULTS

A total of 2532 patients were selected, and 86 patients were excluded. As for the groups, 1219 patients were assigned to group E, and 1227 patients were assigned to group R. As for intraoperative awareness, group E had 2 patients, and group R had 14. Compared with group R, the incidence of intraoperative awareness in group E was significantly lower (p = 0.003); the time-averaged ETS concentration and sevoflurane dosage were lower in group E (p < 0.05); and no significant changes were found in tracheal extubation time, intravenous general anesthetic dosage, or postoperative complication incidence in either group (p > 0.05). The incidence of intraoperative awareness was higher in women than men in group R (p < 0.05).

CONCLUSION

Using ETS-guided anesthesia and maintaining the sevoflurane concentration (0.7-1.3 MAC) can decrease the incidence of patient awareness during endoscopic surgery.

Awareness and Aortocaval Obstruction in Obstetric Anesthesia

Awareness during general anesthesia for cesarean delivery continues to be a major problem. The key to preventing awareness is strict attention to anesthetic technique. The prevalence and implications of aortocaval compression have been firmly established. Compression of the vena cava is a real occurrence when assuming the supine position. Relief of this compression most likely does not occur until the patient is turned 30°, which is not feasible for performing cesarean delivery. Although it is still wise to tilt the patient, the benefit of this tilt may not be as great as once thought.

Efficacy and safety of low-dose ketamine as an adjunct analgesic and amnesic during caesarean section under general anaesthesia

Background and Aims:

The practice of avoiding sedatives or anxiolytics during caesarean section under general anaesthesia (GA) until delivery of the baby could result in exaggerated haemodynamic responses and an increased risk of awareness. We aimed to assess the efficacy and safety of low-dose ketamine, used as an adjunct analgesic and amnesic, in attenuating these responses during caesarean section under GA.

Methods:

This prospective, randomised study was conducted in 40 patients. Group K (n = 20) received 0.25 mg/kg ketamine, whereas Group C received 5 ml normal saline intravenously (IV) just before induction of anaesthesia. After intubation, patients were ventilated with O₂ and N₂O (40:60%) with 0.7% end-tidal isoflurane. Fentanyl and midazolam were given following delivery of the baby. Mann–Whitney and Fisher's exact tests were used for statistical analysis.

Results:

Preinduction haemodynamic parameters and those recorded at 1 min after induction were comparable in both groups. However, heart rate and systolic blood pressure recorded after intubation (at 3, 5, 7, 9, 12, 15, 20, 30 and 45 min after induction) showed significantly high values in Group C (P < 0.05). Mean arterial pressure also showed a similar pattern. Umbilical vein pO₂, pCO₂ and pH were comparable in both groups. Though Apgar score at 1 min showed a higher scoring in Group K, at 5 min both groups had comparable scores. In Group C, intraoperative lacrimation (50% vs. 0%) and hallucinations/recall of intraoperative events (10% vs. 0%) were high.

Conclusion:

IV ketamine 0.25 mg/kg can be safely used as an adjunct analgesic and amnesic to attenuate haemodynamic responses during caesarean section under GA without affecting the foetal outcome.

Propofol-ketamine combination: a choice with less complications and better hemodynamic stability compared to propofol? On a prospective study in a group of colonoscopy patients

BACKGROUND AND AIMS

In this study, we compared duration for reaching desired Ramsay Sedation Score (RSS) and postoperative recovery according to Modified Aldrete Score (MAS) of propofol and propofol-ketamine combination in a group of colonoscopy patients. Rates of cardiovascular, respiratory, laryngospasm, visual and nausea/vomiting complications were also compared as secondary outcomes.

METHODS

This is a double-blinded prospective randomized controlled trial. 95 patients were included and blocked randomized to either propofol (GroupP, n: 47) or propofol-ketamine (GroupPK, n: 48). GroupP patients received 0.5 mg/kg propofol and GroupPK received 0.5 mg/kg ketamine-propofol. Subjects were monitorized noninvasively preoperatively and every 5 min during procedure. RSS was recorded for every minute before starting procedure and for every 5 min during procedure. Recovery after colonoscopy was evaluated according to MAS. Same observer checked for MAS just after procedure in postoperative 1 min and for every 3 min during follow-up. Postoperative respiratory depression was defined as rate <10/min, hypercapnia/hypercarbia-arterial CO2 tension >50 mmHg or SO2 <90 while hypotension was defined as a decrease of 20 % in mean blood pressure compared to initial values.

RESULTS

GroupPK patients needed shorter duration for achieving RSS ≥ 4 (p: 0.038) but longer duration for achieving MAS ≥ 9 (p: 0.005). GroupP's intraoperative blood pressures and heart rates were significantly lower compared to initial values. We observed that respiratory depression (19.1 vs 0 %, p: 0.001), hypotension (29.8 vs 10.4 %, p: 0.018), and nausea/vomiting (17 vs 4.2 %, p: 0.041) were significantly more common in GroupP.

CONCLUSION

Propofol-ketamine combination is an advantageous choice in means of achieving sedation in a shorter period of time, a better hemodynamic stability, less nausea and vomiting and respiratory complication rates. Yet it seems that this choice might be related with longer recovery duration.

Comparison of the Effects of Thiopental Sodium and Propofol on Haemodynamics, Awareness and Newborns During Caesarean Section Under General Anaesthesia

OBJECTIVE

To compare the effects of propofol and thiopental on haemodynamics, awareness and newborns in pregnant women undergoing elective caesarean section.

METHODS

Seventy pregnant women were assigned into two equal groups. For anaesthesia induction, 2 mg kg(-1) propofol (Group P) and 5 mg kg(-1) thiopental (Group T) were administered. Maternal haemodynamic parameters and bispectral index (BIS) values were recorded before induction, in 1-minute intervals within the first 10 minutes after induction and in 5-minute intervals thereafter, during skin incision, uterine incision, removal of infant, uterine sutures, skin sutures, eye opening and extubation in all cases. Cord blood gas analysis and 1- and 5-minute APGAR scores were recorded. In all cases, a keyword was spelled to ear during removal of the infant, and at the first postoperative hour, patients were questioned. Important time periods of surgery and anaesthesia and also the first postoperative hour haemodynamic values, pain scores, nausea and vomiting were noted.

RESULTS

The demographic data were similar among cases. In Group T, systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) at the first 2 minutes after induction and heart rate (HR) at almost all time points were significantly higher. BIS values from induction to the eighth minute and skin incision, uterine incision and removal of the infant were lower in Group P. No patient remembered the keyword spelled, while 4 patients reported dreaming during general anaesthesia. The effects of propofol and thiopental sodium on 1- and 5-minute APGAR scores, cord blood gas values and postoperative visual analogue scale (VAS) scores were similar.

CONCLUSION

Propofol is a more appropriate anaesthetic agent than thiopental in anaesthesia for caesareans, since it provides better anaesthestic depth and more rapid recovery.

Anesthetic management of labor and delivery in patients with elevated intracranial pressure

The anesthetic management of labor and delivery in patients with elevated intracranial pressure is complex. This review discusses the etiologies of diffuse and focal pathologies which lead to elevated intracranial pressure in pregnancy. The role of neuraxial and general anesthesia in the management of labor and delivery is also examined. Finally, a comprehensive review of strategies to minimize increases in intracranial pressure during general anesthesia for cesarean delivery is presented.

Awareness and apgar score in elective Cesarean section under general anesthesia with propofol or Isoflurane: A prospective, randomized, double-blinded clinical trial study

Background:

Awareness is a postoperative recall of events experienced under general anesthesia. In this study, we compared the incidence of awareness between two routine methods used, inhalation (Isoflurane) and intravenous protocol (Propofol), in elective Cesarean section, and also evaluated the effect of these two different methods on the apgar score of newborns.

Materials and Methods:

In this prospective, clinical trial study, 90 pregnant women candidates for elective Cesarean section were randomly enrolled, after taking written consent. Induction of anesthesia in both groups was provided by propofol and succinylcholine in the same manner, and maintenance of anesthesia in Group 1 was provided by propofol 100 μg/kg/minute and in Group 2 with isoflurane 1 MAC, to maintain the bispectral index (BIS) between 45 and 60. Blood pressure, heart rate, electrocardiography (ECG), and also Etco2 and o2sat were recorded throughout the surgery and finally analyzed and compared.

Results:

From 90 patients, four cases of confirmed awareness were found in the propofol group and three cases in the Isoflurane group (8/9% vs. 6/7%), but the apgar scores were comparable between the two groups. Meanwhile there were no significant differences between the two groups in basic information, neonatal apgar scores, hemodynamic changes, and BIS, Electromyography (EMG), and signal quality index (SQI) values.

Conclusion:

According to the patient's state, diagnosis of the anesthesiologist, and other criteria like price and its availability, we could use these drugs in general anesthesia during Cesarean section, although it is recommended that more studies be done to compare the effect of these two drugs in larger groups.

Survey on the adequacy of depth of anaesthesia with bispectral index and isolated forearm technique in elective Caesarean section under general anaesthesia with sevoflurane

BACKGROUND

Awareness during general anaesthesia for Caesarean section (C/S), although uncommon, remains a concern for anaesthesiologists. We examined the relationship between the bispectral index (BIS) and responses to the isolated forearm technique (IFT) to evaluate the adequacy of general anaesthesia in C/S and determine a suitable cut-off point for BIS values based on IFT results.

METHODS

In 61 parturients, a standardized anaesthetic technique was applied. It included sodium thiopental and succinylcholine for induction, and O2, N2O, and sevoflurane for maintenance of anaesthesia. BIS values and IFT response were recorded at 16 predetermined events during anaesthesia.

RESULTS

Positive IFT responses were seen in 41%, 46%, and 23% of the parturients at laryngoscopy, intubation, and skin incision, respectively. BIS could not reliably differentiate between IFT responders and non-responders during these three stages. The receiver operating characteristic curve cut-off points for BIS to predict IFT responders with 100% sensitivity were 34, 37, and 27, respectively, for these stages. In all stages of the operation after skin incision, more than 90% of parturients had no IFT test response, and BIS values between 40 and 63 were associated with negative IFT results. During a structured interview within 12-24 h after the operation, no patient had evidence of explicit recall of intraoperative events.

CONCLUSIONS

The BIS is not reliable for monitoring anaesthesia depth in C/S. Lower than previously recommended values are needed to avoid IFT test responses during laryngoscopy, intubation, and skin incision.

Neuraxial Anesthesia in Parturients with Intracranial Pathology

Parturients with intracranial lesions are often assumed to have increased intracranial pressure, even in the absence of clinical and radiographic signs. The risk of herniation after an inadvertent dural puncture is frequently cited as a contraindication to neuraxial anesthesia. This article reviews the relevant literature on the use of neuraxial anesthesia in parturients with known intracranial pathology, and proposes a framework and recommendations for assessing risk of neurologic deterioration, with epidural analgesia or anesthesia, or planned or inadvertent dural puncture. The authors illustrate these concepts with numerous case examples and provide guidance for the practicing anesthesiologist in determining the safety of neuraxial anesthesia.

Effect of pre-exposure to sevoflurane on the bispectral index in women undergoing Caesarean delivery under general anaesthesia

BACKGROUND

Patients undergoing Caesarean delivery under inhalation anaesthesia are at a high risk of awareness, especially in the period before delivery. We assessed the effects of pre-exposure to sevoflurane on the bispectral index (BIS) in the interval before delivery.

METHODS

Sixty-four patients undergoing elective Caesarean delivery were randomly assigned to receive 1.0-1.1 vol% (control 1) or 1.2-1.3 vol% (control 2) end-tidal sevoflurane, or the same concentrations of end-tidal sevoflurane combined with pre-exposure to 1 vol% sevoflurane for the last 1 min of the preoxygenation period (the preSevo 1 and preSevo 2 groups, respectively). We assessed BIS values, arterial pressure, and heart rate at the time of induction; before intubation; and upon skin incision, uterine incision, and delivery. We also determined the maternal incidence of intraoperative awareness and the neonatal Apgar scores, and conducted umbilical blood gas analysis.

RESULTS

At skin incision, BIS values were significantly lower in the preSevo 1 group than in the control 1 group [50 (13) vs 72 (8), P<0.001] and in the preSevo 2 group than in the control 2 group [44 (11) vs 67 (10), P<0.001]. The mean BIS values in the preSevo 1 and 2 groups were maintained below 60 in the period before delivery. No other parameter differed among groups, and no patient exhibited intraoperative awareness.

CONCLUSIONS

Pre-exposure to low concentrations of sevoflurane reduced BIS values in the interval before delivery, suggesting that this approach may reduce the risk of maternal awareness. Clinical Research Information Service (code KCT0000069, http://cris.cdc.go.kr).

Anesthesia awareness: narrative review of psychological sequelae, treatment, and incidence

Awareness during general anesthesia occurs when patients recall events or sensations during their surgeries, although the patients should have been unconscious at the time. Anesthesiologists are cognizant of this phenomenon, but few discussions occur outside the discipline. This narrative review summarizes the patient recollections, psychological sequelae, treatment and follow-up of psychological consequences, as well as incidence and etiology of awareness during general anesthesia. Recalled memories include noises, conversations, images, mental processes, feelings of pain and/or paralysis. Psychological consequences include anxiety, flashbacks, and posttraumatic stress disorder diagnosis. Limited discussion for therapeutic treatment after an anesthesia awareness experience exists. The incidence of anesthesia awareness ranges from 0.1 to 0.2% (e.g., 1-2/1000 patients). Increased recognition of awareness during general anesthesia within the psychological/counseling community, with additional research focusing on optimal therapeutic treatment, will improve the care of these patients.

Is anesthesia dangerous?

BACKGROUND

Recent years have seen a rise in overall anesthesia-related mortality.

METHOD

Selective review of the literature.

RESULTS

Anesthesia-related mortality has fallen from 6.4/10 000 in the 1940s to 0.4/100 000 at present, largely because of the introduction of safety standards and improved training. The current figure of 0.4/100 000 applies to patients without major systemic disease; mortality is higher among patients with severe accompanying illnesses, yet in this group, too, perioperative mortality can be reduced by appropriate anesthetic management. Moreover, the use of regional anesthesia can also improve the outcome of major surgery.

CONCLUSION

A recent increase in the percentage of older and multimorbid patients among persons undergoing surgery, along with the advent of newer types of operation that would have been unthinkable in the past, has led to an apparent rise in anesthesia-associated mortality, even though the quality of anesthesiological care is no worse now than in the past. On the contrary, in recent years, better anesthetic management has evidently played an important role in improving surgical outcomes.

Awareness under general anesthesia

BACKGROUND

Awareness while under general anesthesia, and the later recall of what happened during surgery, can be experienced by patients as horrific events that leave lasting mental trauma behind. Patients may have both auditory and tactile perception, potentially accompanied by feelings of helplessness, inability to move, pain, and panic ranging to an acute fear of death. For some patients, the experience of awareness under anesthesia has no sequelae; for others, however, it can lead to the development of post-traumatic stress disorder, consisting of complex psychopathological phenomena such as anxiety, insomnia, nightmares, irritability, and depression possibly leading to suicidality.

METHODS

The literature on the subject was selectively reviewed.

RESULTS

In the absence of risk factors awareness phenomena occur in one to two per 1000 operations under general anesthesia (0.1% to 0.2%) and are thus classed as an occasionally occurring critical event. In children, the risk of such phenomena occurring is 8 to 10 times higher. These phenomena are due to an inadequate depth of anesthesia with incomplete unconsciousness. They can be promoted by a number of risk factors that are either patient-related (ASA class III or above, medication abuse), surgery-related (Caesarean section, emergency procedures, surgery at night), or anesthesia-related (anesthesia without benzodiazepines, use of muscle relaxants).

CONCLUSION

Strategies for avoiding awareness phenomena under anesthesia include the training of staff to know about the problem and, specifically, the use of benzodiazepines, the avoidance of muscle relaxants if possible, and shielding the patient from excessive noise. EEG monitoring is effective but provides no guarantee against awareness. If awareness under anesthesia occurs despite these measures, the patient must be given expert, interdisciplinary treatment as soon after the event as possible in order to minimize its potential sequelae.