Bispectral Index Monitoring in Healthy, Cirrhotic, and End-Stage Liver Disease Patients Undergoing Hepatic Operation

The Management of Postoperative Cognitive Dysfunction in Cirrhotic Patients: An Overview of the Literature

Background and objectives: Postoperative cognitive dysfunction (POCD) represents a decreased cognitive performance in patients undergoing general anesthesia for major surgery. Since liver cirrhosis is associated with high mortality and morbidity rates, cirrhotic patients also assemble many risk factors for POCD. Therefore, preserving cognition after major surgery is a priority, especially in this group of patients. The purpose of this review is to summarize the current knowledge regarding the effectiveness of perioperative therapeutic strategies in terms of cognitive dysfunction reduction. Data Collection: Using medical search engines such as PubMed, Google Scholar, and Cochrane library, we analyzed articles on topics such as: POCD, perioperative management in patients with cirrhosis, hepatic encephalopathy, general anesthesia in patients with liver cirrhosis, depth of anesthesia, virtual reality in perioperative settings. We included 115 relevant original articles, reviews and meta-analyses, and other article types such as case reports, guidelines, editorials, and medical books. Results: According to the reviewed literature, the predictive capacity of the common clinical tools used to quantify cognitive dysfunction in cirrhotic settings is reduced in perioperative settings; however, novel neuropsychological tools could manage to better identify the subclinical forms of perioperative cognitive impairments in cirrhotic patients. Moreover, patients with preoperative hepatic encephalopathy could benefit from specific preventive strategies aimed to reduce the risk of further neurocognitive deterioration. Intraoperatively, the adequate monitoring of the anesthesia depth, appropriate anesthetics use, and an opioid-sparing technique have shown favorable results in terms of POCD. Early recovery after surgery (ERAS) protocols should be implemented in the postoperative setting. Other pharmacological strategies provided conflicting results in reducing POCD in cirrhotic patients. Conclusions: The perioperative management of the cognitive function of cirrhotic patients is challenging for anesthesia providers, with specific and targeted therapies for POCD still sparse. Therefore, the implementation of preventive strategies appears to remain the optimal attitude. Further research is needed for a better understanding of POCD, especially in cirrhotic patients.

Optimal anesthetic conduct regarding immediate and short-term outcomes after liver transplantation - Systematic review of the literature and expert panel recommendations

BACKGROUND

In the era of enhanced recovery after surgery, there is significant discussion regarding the impact of intraoperative anesthetic management on short-term outcomes following liver transplantation (LT), with no clear consensus in the literature.

OBJECTIVES

To identify whether or not intraoperative anesthetic management affects short-term outcomes after liver transplantation.

DATA SOURCES

Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central.

METHODS

A systematic review following PRISMA guidelines was undertaken. The systematic review was registered on PROSPERO (CRD42021239758). An international expert panel made recommendations for clinical practice using the GRADE approach.

RESULTS

After screening, 14 studies were eligible for inclusion in this systematic review. Six were prospective randomized clinical trials, three were prospective nonrandomized clinical trials, and five were retrospective studies. These manuscripts were reviewed to look at five questions regarding anesthetic care and its impact on short term outcomes following liver transplant. After review of the literature, the quality of evidence according to the following outcomes was as follows: intraoperative and postoperative morbidity and mortality (low), early allograft dysfunction (low), and hospital and ICU length of stay (moderate).

CONCLUSIONS

For optimal short term outcomes after liver transplantation, the panel recommends the use of volatile anesthetics in preference to total intravenous anesthesia (TIVA) (Level of Evidence: Very low; Strength of Recommendation: Weak) and minimum alveolar concentration (MAC) versus bispectral index (BIS) for depth of anesthesia monitoring (Level of Evidence: Very low; Strength of Recommendation: Weak). Regarding ventilation and oxygenation, the panel recommends a restrictive oxygenation strategy targeting a PaO₂ of 70-120 mmHg (10-14 kPa), a tidal volume of 6-8 ml/kg ideal body weight (IBW), administration of positive end expiratory pressure (PEEP) tailored to patient intraoperative physiology, and recruitment maneuvers. (Level of evidence: Very low; Strength of Recommendation: Strong). Finally, the panel recommends the routine use of antiemetic prophylaxis. (Level of evidence: low; Strength of Recommendation: Strong).

Comparison of bispectral index targeted end-tidal concentration of desflurane during three phases of orthotopic liver transplantation

Background and Aims:

Reduced inhalational anaesthetic requirement in end-stage liver disease during living donor orthotopic liver transplantation (LD-OLT) is due to increased endogenous opioids. This study evaluated the changes in bi-spectral index (BIS) monitored end-tidal desflurane (ET_Des) requirements during ‘dissection’, ‘anhepatic’, and ‘neohepatic’ phases of LD-OLT.

Methods:

This prospective, cohort study included 40 adults undergoing LD-OLT under general anaesthesia (GA). All patients received BIS-guided desflurane GA. ET_Des requirements in three phases of LD-OLT (primary objective); relationship between inhalational anaesthetic requirements and severity of liver disease; and effect of changes in mean arterial pressure (MAP) and body temperature on ET_Des concentration for all three phases were also evaluated.

Results:

ET_Des during the ‘dissection’ phase (2.92 ± 0.65%) was > ‘anhepatic’ (2.68 ± 0.85%, P = 0.049) and ‘neohepatic’ phases (2.58 ± 0.71%, P = 0.005). Patients with model of end-stage liver disease (MELD) score < 20 returned significantly greater ET_Des than those with MELD score ≥20 during the ‘dissection’ (MELD <20: 3.11 ± 0.49%; MELD ≥20: 2.58 ± 0.77%, P = 0.01) and ‘anhepatic’(MELD <20: 2.96 ± 0.76%; MELD ≥20: 2.17 ± 0.79%, P = 0.003) phases. A positive correlation was observed between ET_Des(r = 0.584, P = 0.001) and temperature in the ‘dissection’ phase only.

Conclusion:

In patients undergoing LD-OLT, BIS monitoring guidance of depth of desflurane GA suggests lower desflurane requirements during ‘anhepatic’ and the ‘neohepatic’ phase of surgery. Also, the desflurane requirement is greater in patients with lesser severity of liver disease.

Pilot study of closed-loop anaesthesia for liver transplantation

BACKGROUND

Automated titration of propofol and remifentanil guided by the bispectral index (BIS) has been used for numerous surgical procedures. Orthotopic liver transplantation (OLT) uniquely combines major changes in circulating volume, an anhepatic phase, and ischaemia-reperfusion syndrome. We assessed the behaviour of this automated controller during OLT.

METHODS

Adult patients undergoing OLT were included in this pilot study. Consumption of propofol and remifentanil was calculated for each surgery period (dissection, anhepatic, and liver reperfusion phases). Arterial blood samples were collected at several time points to allow comparison of actual with calculated propofol and remifentanil concentrations. Data are presented as median [25th and 75th percentiles] or percentage (95% confidence interval).

RESULTS

Thirteen patients were studied. System performance, defined as the percentage of time with BIS in the range 40-60, was 88% (86-94) of the total duration of anaesthesia. Propofol requirement was decreased during the anhepatic phase compared with the dissection phase (2.9 [1.9-5.0] mg kg(-1) h(-1) and 4.6 [3.5-8.1] mg kg(-1) h(-1); P<0.03) while remifentanil consumption was unchanged (0.11 [0.09-0.19] µg kg- (1) min(-1)). Bland-Altman analysis showed a weak concordance for propofol (bias of 0.7 µg ml(-1) and limits of agreement of -2.2 to +3.7 µg ml(-1)) and remifentanil (bias of 1.3 ng ml(-1) and limits of agreement -4.3 to +6.8 ng ml(-1)). No adverse events were reported during anaesthesia.

CONCLUSIONS

This pilot study indicates that automated titration of propofol and remifentanil guided by the BIS is feasible during OLT.

The anhepatic phase extended by temporary portocaval shunt does not affect anesthetic sensitivity and postoperative cognitive function: A case-control study

Temporary portocaval shunt (TPCS) prolongs the duration of the anhepatic phase, during which anesthetic sensitivity is highest among the 3 phases of living donor liver transplantation (LDLT). Cognitive dysfunction has been associated with increased anesthetic sensitivity and poor hepatic function. Therefore, we assessed anesthetic sensitivity to desflurane and perioperative cognitive function in patients undergoing LDLT, in whom the duration of the anhepatic phase was extended by TPCS to test the hypothesis that the prolonged anhepatic phase increases anesthetic sensitivity and causes postoperative cognitive decline.This case-control study was conducted in 67 consecutive patients undergoing LDLT from February 2014 to January 2016. Anesthesia was maintained at a 0.6 end-tidal age-adjusted minimum alveolar concentration of desflurane. The bispectral index (BIS) was maintained at less than 60 and averaged at 1-minute intervals. The mini-mental state examination (MMSE-KC) was performed 1 day before and 7 days after the LDLT. All parameters were compared between the patients undergoing TPCS (TPCS group) and the remaining patients (non-TPCS group).TPCS was performed in 16 patients (24%). TPCS prolonged the duration of the anhepatic phase (125.9 ± 29.4 vs 54.9 ± 20.5 minutes [mean ± standard deviation], P < 0.0001). The averaged BIS values during the 3 phases were comparable between the 2 groups. No significant interval changes in the averaged BIS values were observed during the 3 consecutive phases. Similarly, there were no significant differences in MMSE-KC score assessed 1 day before and 7 days after LDLT between the 2 groups. The preoperative MMSE-KC scores were unchanged postoperatively in the 2 groups.The extension of the anhepatic phase did not affect anesthetic sensitivity and postoperative cognitive function.

Effect of the severity of liver dysfunction on the minimum alveolar concentration of sevoflurane responding to an electronic stimulation in cirrhotic patients

BACKGROUND

It has been observed that patients with liver dysfunction need lower dose anesthetic compared patients with normal liver function. The minimum amount of volatile anesthetic to achieve an optimal depth of anesthesia for these patients is still unclear. In this study, Minimum alveolar concentration (MAC) of the sevoflurane was determined using an electric stimulation and the effect of severity of liver dysfunction on the MAC was observed in cirrhotic patients.

METHODS

Thirty patients undergoing upper abdominal surgery were divided into the following groups: group N (normal liver function), group A (Child-Pugh grade A) and group B (Child-Pugh grade B-C). Neuropsychological tests were performed before surgery. We measured MAC_electric (minimum alveolar concentration that prevents movement in response to an electric stimulation in 50 % of patients) of sevoflurane in cirrhotic patients with liver dysfunction using an electrical stimulation of 80 mA at 50 Hz, and analyzed factors that associated change of MAC.

RESULTS

According to the neuropsychological tests, there were 7 and 4 patients with minimal hepatic encephalopathy in Groups B and A, respectively. MAC_electric in cirrhotic patients with liver dysfunction decreased significantly compared to that in healthy liver patients (1.51 ± 0.16 vol. %, 1.33 ± 0.14 vol. % and 1.17 ± 0.13 vol. % in Group N, A and B, respectively), while MAC_electric was comparable between the cirrhotic patients with different Child-Pugh grade. The Alanine Aminotransferase (ALT) and baseline values of bispectral index (BIS) were risk factors associated with the lowering of MAC_electric (p < 0.05).

CONCLUSION

MAC_electric of sevoflurane in cirrhotic patients was significantly lower than that of patients with a healthy liver. The severity of liver dysfunction had no effect on the MAC_electric of sevoflurane in cirrhotic patients.

TRIAL REGISTRATION

This study has been registered in the Chinese Clinical Trial Register in August 3, 2011 (No. ChiCTR-TRC-11001507 ).

Entropy-guided end-tidal desflurane concentration during living donor liver transplantation

Background:

The three phases of living donor liver transplantation (LDLT) represent different liver conditions. The aim is to study the required end-tidal desflurane concentration (ET-Des) guided with entropy monitoring for the depth of anesthesia.

Methods:

After the Ethics and Research Committee approval, 40 patients were included in this prospective study. Anesthesia was maintained with Desflurane-O2-air. State entropy (SE) and Response entropy (RE) were kept between 40 and 60.

Results:

Age and Model for End-stage Liver Disease (MELD) score were 45±10 years and 15.43±3.92, respectively. ET-Des were significantly lower in the anhepatic phase (2.8±0.4%) than in the pre-anhepatic and neohepatic phases (3.3±0.3%, 3.47±0.3%, respectively, P<0.001). The SE and RE for pre-anhepatic, anhepatic, and neohepatic phases were (45.6±3.7, 47.4±3.2), (44.7±2.1, 46.4±2.04), and (46.1±3.3, 47.9±3.3), respectively, with no significant changes between the phases, P > 0.05. Total operative time was 651±88 minutes, and for each phase it was 276±11, 195±55, and 191±24 minutes, respectively. Significant changes were found in hemoglobin g/dl and hematocrit % between the three phases (10.28±1.5, 30.48±4.3), (9.45±1.34, 28.36±4.1), and (8.88±1.1, 26.63±3.5), P<0.05. The heart rate and mean blood pressures were stable despite the cardiac index demonstrated a significant reduction during the anhepatic phase (2.99±0.22) when compared to the pre-anhepatic and neohepatic phases (3.60±0.29) and (4.72±0.32), respectively, (P<0.05). There was a significant correlation between CI and ET-Des% (r=0.604, P<0.05).

Conclusion:

Inhalational anesthetic requirements differed from one phase to another during LDLT, with requirements being the least during the anhepatic phase. Monitoring of the anesthesia depth was required, to avoid excess administration, which could compromise the hemodynamics before the critical time of reperfusion.

The influence of the severity of chronic virus-related liver disease on propofol requirements during propofol-remifentanil anesthesia

PURPOSE

The purpose of this study was to investigate the influence of chronic virus- related liver disease severity on propofol requirements.

MATERIALS AND METHODS

In this study, 48 male patients with chronic hepatitis B infection were divided into three groups according to Child-Turcotte-Pugh classification of liver function (groups A, B, and C with mild, moderate and severe liver disease, respectively). After intubation, propofol concentration was adjusted by ± 0.3 μg/mL increments to maintain bispectral index in the range of 40-60. Target propofol concentrations at anesthesia initiation, pre-intubation and pre-incision were recorded.

RESULTS

The initial concentration used in group C was significantly lower than that used in group A or B (p<0.05), whereas no difference was observed between groups A and B. At pre-intubation, the actual required concentration of propofol increased significantly (3.2 μg/mL) in group A (p<0.05), which lead to significant differences between the groups (p<0.05). At pre-incision, the requirements for propofol decreased significantly in both groups A and B (3.0 μg/mL and 2.7 μg/mL, respectively) compared with those at pre-intubation (p<0.05), and were significantly different for all three groups (p<0.05), with group C demonstrating the lowest requirement (2.2 μg/mL). The required concentrations of propofol at pre-incision were similar to those at induction.

CONCLUSION

In this study, propofol requirements administered by target-controlled infusion to maintain similar depths of hypnosis were shown to depend on the severity of chronic virus-related liver dysfunction. In other words, patients with the most severe liver dysfunction required the least amount of propofol.

Clinical practice of early extubation after liver transplantation

BACKGROUND

Anesthetic practices such as early tracheal extubation facilitate postoperative recovery. Early extubation after liver transplantation has been adopted by some centers in the recent two decades. No universal clinical guidelines are used and questions remain. This review aimed to address the current status of early extubation after liver transplantation.

DATA SOURCES

A literature search of MEDLINE and ISI Web of Knowledge databases was performed using terms such as liver transplantation, early extubation, immediate tracheal extubation, fast tracking or fast track anesthesia and postoperative tracheal extubation. Additional papers were identified by a manual search of the references in the key articles.

RESULTS

Review of the available literature provided an insight into the definition, evolution, advantages and risks of early extubation, and anesthetic techniques that prompt early extubation in liver transplant patients. Early extubation has proved to be feasible and safe in these patients, but the outcomes are still uncertain.

CONCLUSIONS

Early extubation after liver transplantation is feasible, safe and cost-effective in the majority of patients and has been increasingly accepted as an option for conventional postoperative ventilation. Comprehensive and individualized evaluation of the patient's condition before extubation by an experienced anesthesiologist is the cornerstone of success. Understanding of its effect on the outcome remains incomplete. In the future, additional trials are required to establish universal early extubation guidelines and to determine its benefits for patients and practitioners.

Liver transplantation: Advances and perioperative care

Liver transplantation is one of the treatments for many-life threatening liver diseases. Numerous advances in liver transplant surgery, anaesthesia and perioperative care have allowed for an increasing number of these procedures. The purpose of this review is to consider some of the important advances in perioperative care of liver transplant patients such as pre-operative evaluation, intraoperative monitoring and management and early extubation. A PubMed and EMBASE search of terms “Anaesthesia” and “Liver Transplantation” were performed with filters of articles in “English”, “Adult” and relevant recent publications of randomised control trial, editorial, systemic review and non-systemic review were selected and synthesized according to the author's personal and professional perspective in the field of liver transplantation and anaesthesia. The article outlines strategies in organ preservation, training and transplant database for further research.

Minimum alveolar concentration of sevoflurane in rabbits with liver fibrosis

BACKGROUND

Sevoflurane is widely used in patients undergoing surgical procedures, which could affect both the liver function and hepatic blood flow. However, the effects of liver fibrosis on minimum alveolar concentration (MAC) of sevoflurane are still unclear. Therefore, we designed this study to determine the MAC of sevoflurane in rabbits with liver fibrosis.

METHODS

Thirty male New Zealand white rabbits weighing approximately 2.5 kg were divided randomly into 2 groups: fibrosis (n = 20) and normal control group (n = 10). The rabbits in the fibrosis group were treated with 50% carbon tetrachloride for 12 weeks to induce liver fibrosis. The serum concentration of total protein, albumin, globulin, total bile acids, alanine aminotransferase, aspartame aminotransferase, alkaline phosphatase, γ-glutamyl transpeptidase, total bilirubin, direct bilirubin, and indirect bilirubin were measured before anesthesia. The anesthesia for animals that survived in both groups was induced and maintained with sevoflurane. A standard tail-clamp technique was used to determine the MAC of sevoflurane in spontaneously breathing rabbits. After anesthesia, animals were killed for liver pathologic examination.

RESULTS

Twelve weeks after 50% carbon tetrachloride administration, 14 of 20 rabbits survived in the fibrosis group, and 9 of 10 survived in the control group. All surviving animals in the fibrosis group had developed moderate to severe liver fibrosis. Three rabbits that survived after the fibrosis challenge were excluded for other diseases or no response to pain stimulation. The levels of globulin, aspartame aminotransferase, and γ-glutamyl transpeptidase significantly increased in fibrosis animals compared with controls. However, the albumin and alkaline phosphatase levels were significantly lower in the fibrosis group than in the control group. Mean arterial blood pressure, heart rate, end-tidal CO(2), and temperature were stable in both groups during sevoflurane anesthesia. The MAC of sevoflurane was significantly less in the fibrosis group than in the control group (3.52% vs 4.10%, P = 0.018).

CONCLUSION

The MAC of sevoflurane decreased significantly in rabbits with liver fibrosis.

The relationship between inhalational anesthetic requirements and the severity of liver disease in liver transplant recipients according to three phases of liver transplantation

PURPOSE

Orthotopic liver transplantation (OLT) patients are known to show decreased intraoperative anesthetic requirements compared with patients undergoing other liver surgeries. The aim of this study was to determine the relationship between inhalational anesthetic requirements and the severity of liver disease among OLT patients.

METHODS

Fifty patients undergoing first living donor OLT were divided into 2 groups: model for end-stage liver disease (MELD) score<20 (low-MELD group; n=25) versus, MELD score>or=20 (high-MELD group; n=25). Anesthesia was maintained with desflurane and inspired concentration was titrated to maintain the bispectral index between 40 and 50. Neither intraoperative opioid nor epidural or intrathecal analgesia was used. End-tidal desflurane concentration (ETdes) was measured every 5 minutes and averaged in 30-minute intervals. These values were divided into 3 phases: preanhepatic (P 0.5 hour, P 1 hour, and P 1.5 hours), anhepatic (A 0.5 hour, A 1 hour, A 1.5 hours, and A 2 hours), and postreperfusion (R 0.5 hour, R 1 hour, R 1.5 hours, R 2 hours, R 2.5 hours, and R 3 hours). Results were compared between the 2 groups.

RESULTS

The demographic and intraoperative data were similar between the 2 groups. ETdes to maintain comparable anesthetic depth was significantly lower during the preanhepatic and anhepatic phases in the high-MELD than the low-MELD group, but there was no significant difference during the postreperfusion period.

CONCLUSIONS

OLT patients with high MELD scores showed less inhalational anesthetic requirements during the preanhepatic and the anhepatic periods than those with low MELD scores.