The Study of Postoperative Recall in Patients under Total Intravenous Anesthesia.

Background: The incidence of postoperative recall under total intravenous anesthesia (TIVA) is not yet fully established. Avoidance of inhalational agent is a known risk factor for awareness. In addition, lack of reliable technique to monitor drug concentration needed for adequate depth of anesthesia makes TIVA challenging. Hence, we intend to evaluate our standard anesthesia practice for postoperative recall. Methodology: This questionnaire-based observational study was done over the period of 2 years. We enrolled 1080 adult (American Society of Anesthesiologists physical status Class I or II) patients undergoing TIVA for Endoscopic retrograde cholangiopancreatography (ERCP). All patients received fentanyl, midazolam and propofol-based anesthesia. Manual boluses of propofol were given to achieve adequate sedation. (Ramsay sedation scale of 5) in accordance with clinical signs as judged by the primary anesthesiologist. Postoperatively within 12-24 h, patients were assessed for recall using Brice questionnaire. Primary outcome was number of patients reporting postoperative recall in the Brice interview. Secondary outcome was the incidence of dreaming.
Results: On postoperative interview, none of the patients reported awareness. 12.5% of patients had dreams which were pleasant. None of the dreams was unpleasant. The worst thing about surgery was pain.
Conclusion: Our study suggests that if adequate doses of propofol are adhered to and necessary action is taken against responses indicating wakefulness, postoperative recall under TIVA is an uncommon occurrence. Copyright:

INTRODUCTION

Awareness is a rare but potential stressful complication of anesthesia. It can lead to posttraumatic stress disorder, fear of future anesthetics and sleep disturbances. Awareness is defined as the unintended explicit recall of an event. The incidence of awareness varies from 0.1%-0.2% in general population to 11%–40% in high-risk population.[1] To establish whether an event of intraoperative awareness has occurred or not, it is crucial to talk to the patient postoperatively. Endoscopic retrograde cholangiopancreatography (ERCP) is a complex procedure requiring a deeper level of anesthesia. Adequate depth of anesthesia increases the success rate. Total intravenous anesthesia (TIVA) for ERCP is a standard care of practice at our institute. Awareness is a greater risk with TIVA than end-tidal anesthetic agent concentration-based inhalational anesthesia. TIVA has been associated with increased risk of awareness as there is a lack of real-time monitoring of blood anesthetic concentration.[2345] With the growing popularity of propofol-based TIVA, we wished to study the incidence of postoperative recall in these patients.

METHODOLOGY

The study protocol was approved by the hospital ethical committee. (MSRMC/EC/2017, Ethical committee registration number ECR/215/Inst/KA/2013/RR-16 dated 25/07/2017). Informed written consent was obtained from the participants.

This questionnaire-based observational study was done over the period of 2 years. (August 2017 – July 2019) We enrolled 1084 adults with the American Society of Anesthesiologists physical status Class I or II (ASA I/II) patients undergoing TIVA for ERCP. Patients who are not able to communicate, obese patients (body mass index 30 kg.m‒2) were excluded. We attempted to do a pragmatic study without changing the standard anesthesia practice which we follow for ERCP. Standard ASA monitors were applied and supplemental oxygen is given through nasal prongs. Patients were premedicated with (i.v.) midazolam and (i.v.) fentanyl as anesthesia was induced with propofol as primary agent. Propofol was given as a bolus dose of mg.kg-1 followed by continuous infusion titrated to the anesthesia depth. Goal is to achieve Ramsay Sedation Scale of 5. Depth of anesthesia monitors (DOA) was not used. Additional doses of propofol were given to maintain the depth of anesthesia as judged by clinical signs. The commonest indications for incremental doses of propofol were the passage of time, movement of the limbs, “mouthing” on the endoscope, respiratory movements. Any anesthesia-related adverse events such as bradycardia, hypotension, hypoxia and number of patients requiring intubation and ventilation were noted. After completion of the procedure, patients were monitored in the recovery room for half an hour. Postoperatively, patients were assessed for explicit recall using Modified Brice questionnaire [Appendix 1].[67] The interview were done postoperatively within 12–24 h. An independent anesthesiologist visited the patient postoperatively and after discussion with patient, they filled the questionnaire. The patient's responses were subsequently verified by the operating room incharge anesthetist. Awareness was defined as a recall of an intraoperative event confirmed by the attending personnel present in the operating room. Patient's reports unrelated to surgical or anesthesia events were classified as miscellaneous category. If there was evidence of definitive awareness, patients were counseled and psychological support was given.

Statistical consideration

Previous studies have found the incidence of awareness following TIVA technique to be approximately 1%–19%.[2345] Hence sample size of 1042 would allow us to detect the incidence of 2% with 0.85% as margin of error and 95% confidence level. To compensate for dropout cases we enrolled 1084 cases. Data were entered into statistical software (SPSS 18.0, SPSS Inc., Chicago, IL, USA) for analysis. Descriptive statistics was used to report results.

Primary outcome was number of patients reporting definitive awareness in Brice interview. Secondary outcome was incidence of dreaming.

RESULTS

Out of 1084 patients, interview was completed in 1060 patients. Twenty four patients were excluded due to data loss, inability to complete interview or procedure-related complication necessitating intensive care unit care.

The demographic characteristics are shown in Table 1. The various indications for ERCP and duration of procedure are given in Table 2. On postoperative interview, none of the patients had an explicit recall of intraoperative events. Events reported by patients at various time points are shown in Tables 3-5. 12.5% of patients had dreams which were pleasant. None of the dreams was disturbing to the patient. Worst thing about surgery was pain.

Table 1

Demographic data

Parameter	Mean±SD
Age (Yrs)	37.54 (11.99)
Weight (Kg)	59.26 (9.95)
Height (cm)	160.55 (9.05)
BMI (kg/m2)	23.03 (3.74)
Male:Female (%)	43.8:56.2

BMI: Body mass index; SD: Standard deviation

Table 2

Indications and duration of ERCP

Diagnosis	%
Cholelithiasis	35.6%
Choledocholithiasis	44.4%
Obstructive Jaundice	8.9%
Cholangitis	11.1%
Duration of Procedure (min)	45.0±12.6

Table 3

Events reported by patients before going to sleep

Events	Number of patients (%)
Preparation of surgery/Anaesthesia	299 (28.2%)
Operating room personnel	153 (14.5%)
Entering operation room	93 (8.65%)
Administration of drugs	75 (7.1%)
Breathing from nasal canula	34 (3.2%)
Anxiety	174 (16.5%)
None	127 (12%)
Miscellaneous	105 (9.9%)

Table 5

Unpleasant events reported by patients about the procedure

Events	Number of patients (%)
Pain	578 (54.6%)
Sore throat	106 (10%)
Bloating sensation	98 (9.2%)
Fear	6 (0.6%)
Insertion of IV line	26 (2.4%)
Dyspnoea	4 (0.4%)
None	158 (14.8%)
Miscellaneous	84 (8%)

DISCUSSION

In the present study, we did not find any case of awareness on postoperative interview. 12.5% of patients had dreams which were pleasant. None of the dreams were unpleasant. The worst thing about surgery was pain. Most of the patients remembered perioperative events but there was nothing suggestive of explicit awareness.

True awareness is difficult to objectify. Some patients may dream around the surgery or recall conversation as they regain consciousness. Although this does not account for awareness, it may lead to the diagnostic uncertainty. One of the well-established and valid methods of detecting awareness is “Brice questionnaire.” The Brice questionnaire consists of five basic questions and the modified version has multiple answers. Modified Brice questionnaire is more reliable way than unstructured postoperative questioning to detect explicit recall.[8]

DOAs are a poor estimate of actual consciousness of patients. The B-aware trial proved that BIS guided anesthesia reduces the awareness incidence.[9] On the contrary, B-Unaware trial and BAG-RECALL trial could not establish the superiority of BIS over ETAC monitoring for preventing awareness in high-risk population.[1011] They recommended ETAC 0.7-1.3MAC is sufficient to prevent awareness event when using inhalational agent.

The incidence of awareness is higher in TIVA as compared to inhalational anesthesia. The reason is multifactorial. While in inhalational anesthesia end-tidal anesthetic agent monitor gives a fair idea about the depth of anesthesia, there is no real-time monitor to measure actual drug concentration in TIVA. Propofol is known to have wider interpatient variability. We did not use Target control infusion (TCI) because of its unavailability. The problem with TCI is actual plasma drug concentration may differ from display monitor concentration.[12] There is no standard regime for conducting TIVA. TIVA technique can be breached by pump malfunction, disconnection of infusion lines and intravenous cannula. Challenges inherent in monitoring TIVA technique and difficulty in calculating adequate bolus or infusion rate, DOAs are recommended in TIVA technique. Premedication with benzodiazepine is shown to reduce propofol requirement as well as awareness incidence.

The reported incidence of dreaming under anesthesia is 1%–22%.[13] It is still poorly known phenomenon. It may be associated with a lighter plane of anesthesia and may represent near-miss awareness. Samuelsson et al. have found that awareness is 19 times common in the patients who had dreams.[14] Our study had an incidence of 12.5%. Although all dreams were pleasant, the content was unrelated to intraoperative events.

There are few limitations in our study. Interview for awareness was carried out only for once. Due to logistic reasons, we could not follow-up cases after hospital discharge. Studies have shown that multiple interviews at various time interval increases the detection rate of awareness. Some patients are able to recollect awareness immediately after surgery while others may not realize it until months. The gold standard technique to establish awareness is the isolated forearm technique (IFT). Sanders et al. noticed that even intraoperative positive IFT responses were not associated with postoperative recall.[15] This may suggest that subhypnotic doses of anesthetic agents are sufficient in suppressing memory formation. A wider range of incidence of awareness in literature reflects the need of a brain function monitor to investigate anesthesia-induced unconsciousness.

Awareness has potential consequences for patients as well as for anesthetist too. Apart from being stressful to patients, it can cause serious medico-legal implications. As per the evaluation by ASA Closed Claim Project, awareness accounted for 1.9% of claims.[16]

In an order to get true estimate of postoperative recall, we neither changed our standard anesthesia technique nor used any DOA monitors. This ascertains us that the finding of the study could be applicable to day-to-day basis. Premedication with amnestic agent and vigilant monitoring of stressful responses suggesting lighter plane of anesthesia is a key for preventing awareness.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Table 4

Events reported by patients after recovery from anaesthesia

Events	Number of patients (%)
Recovery room	365 (34.5%)
Conversation in operating room	90 (8.5%)
Family	35 (3.5%)
Conversation with physician	50 (4.7%)
Waking up in the operating room	23 (2.2%)
Transfer to bed	103 (9.7%)
Breathing through nasal canula	64 (6.1%)
None	135 (12.6%)
Miscellaneous	195 (18.4%)