A 53-yr old woman (body weight: 63 kg, height: 162 cm) was scheduled for living donor liver transplantation due to acuteon-chronic liver failure. Thirteen years ago, she was diagnosed with hepatitis B related liver cirrhosis. Two days ago, she was intubated due to rapidly developing grade 3-4 hepatic encephalopathy. In the preoperative evaluation, the chest X-ray, electrocardiography, and echocardiography were within normal range. Her laboratory examination showed Hb 7.9 g/dl, platelet count 27 × 10⁹/L, prothrombin time 3.5 international normalized ratio, fibrinogen 52 mg/dl, antithrombin III 6%, sodium 136 mmol/L, potassium 3.9 mmol/L, creatinine 3.8 mg/dl, glucose 163 mg/dl, albumin 3.1 g/dl, total bilirubin 52.8 mg/dl, and ammonia 205 µmol/L. Her Child-Pugh and Model for End-Stage Liver Disease scores were 12 and 49, respectively. However, brain computerized tomography and invasive ICP monitoring could not be performed because the acute exacerbation of her clinical condition requires urgent liver transplantation.

Upon arrival at the operating room, she was still intubated and was in a comatose state. Dopamine of 10 µg/kg/min, dobutamine of 15 µg/kg/min, and norepinephrine of 0.1 µg/kg/min had been administered continuously. Her systolic/diastolic/mean arterial blood pressure and heart rate were 100/50/67 mmHg and 80 beats/min, respectively. After establishing the standard monitoring used in our institute, ultrasound ONSD measurements were done by a physician well-trained in ocular ultrasonography before anesthetic induction. Based on the method described in a previous report [8], both eyes were scanned using a 7.5-MHz probe (ProSound SSD-4000, ALOKA, Tokyo, Japan) through closed eyelids with the patient in the supine position. Right and left eyes were scanned in both sagittal and transverse planes, and the ONSD value was calculated by estimating the average results of these measurements. The ONSD was measured 3 mm posterior to the globe in each eye. Her ONSD just before anesthesia induction was 6.4 mm (Fig. 1A). Simultaneously, TCD was performed to assess cerebral blood flow velocity and ICP noninvasively. Transtemporal insonation of the left middle cerebral artery was done using a 2-MHz probe (Companion III, Viasys Healthcare, Warwick, UK). TCD measurements showed her systolic/diastolic/mean cerebral flow velocities were 100/7/37 cm/s (normal reference values of systolic/diastolic/mean velocities [mean ± SD]: 77.1 ± 12.23/37.4 ± 7.13/50.6 ± 8.42 cm/s). The resistance index was 0.93 (normal reference value: 0.52 ± 0.05) and the pulsatility index was 2.5 (normal reference value: 0.80 ± 0.13), and the second systolic peak (Windkessel effect) was lost, suggesting elevated ICP (Fig. 1B) [6,9]. The bispectral index and suppression ratio were 30 and 20, respectively, and right and left regional cerebral oxygen saturations were 15/15%.

Anesthesia was induced with thiopental and vecuronium, and was maintained using 0.5-1% isoflurane, a 50% O₂/air mixture, and continuous infusion with fentanyl and vecuronium. The patient's lungs were ventilated with a tidal volume of 10-12 ml/kg at a respiratory rate of 10-12 breaths/min to maintain hypocarbia (P_aCO₂: 28-32 mmHg) throughout the procedure. Also, mild hypothermia (34-35℃) was induced, and mannitol of 40 g was administered every six hours for the management of ICP. After anesthesia induction, her arterial blood gas analysis showed a pH of 7.33, a P_aCO₂ of 28 mmHg, a PaO₂ of 209 mmHg, bicarbonate of 14.8 mEq/L, and base excess of -10.0 mmEq/L. Intraoperative hemodynamics and laboratory data were shown Table 1.

After finishing surgery, she was transferred to the surgical intensive care unit. On the second postoperative day, right and left pupil size were 3/3 mm. According to Glasgow coma scale evaluation, eye opening score was 4, best motor response score was 4, best verbal response score was not evaluated due to endotracheal intubation. Bispectral index score ranged from 70 to 90. However, on the third postoperative day, she was developed septic shock, and the patient died by septic shock on the fourth postoperative day.

A 40-yr old man (body weight: 73 kg, height: 172 cm) was scheduled for living donor liver transplantation surgery due to acute liver failure. One week ago, he developed grade 1 hepatic encephalopathy. In the preoperative evaluation, electrocardiography and echocardiography were within normal range. Chest X-ray showed mild pleural effusion on both lungs. His laboratory examination showed Hb 9.9 g/dl, platelet count 107 × 10⁹/L, prothrombin time 2.2 international normalized ratio, fibrinogen 82 mg/dl, antithrombin III 12%, sodium 135 mmol/L, potassium 3.0 mmol/L, creatinine 1.1 mg/dl, glucose 144 mg/dl, albumin 3.0 g/dl, total bilirubin 23.1 mg/dl, and ammonia 82 µmol/L. Her Child-Pugh and Model for End-Stage Liver Disease scores were 12 and 28, respectively.

Upon arrival at the operating room, his mental state was alert. His systolic/diastolic arterial blood pressure and heart rate were 132/68 mmHg and 98 beats/min, respectively. After establishing institutional standard monitoring, an ultrasound ONSD measurement was done by a physician well-trained in ocular ultrasonography. His ONSD just before anesthesia induction was 4.8 mm (Fig. 2A). The bispectral index and suppression ratio were 98 and 0, respectively, and right and left regional cerebral oxygen saturations were 43 and 44%, respectively.

General anesthesia was induced and maintained by the standard protocol at our institute. His lungs were ventilated with a tidal volume of 8-10 ml/kg at a respiratory rate of 10 breaths/min (P_aCO₂, 35-40 mmHg). Intraoperative hemodynamics and laboratory data were shown Table 1. He experienced severe hypotension (systolic/diastolic arterial blood pressure: 62/48 mmHg) and bradycardia (56 beats/min) after graft reperfusion, and was treated with epinephrine (20 µg), after which systolic/diastolic arterial blood pressure (122/72 mmHg) and heart rate (92 beats/min) rapidly recovered to within the normal limit. His ONSD was dilated at 5.7 mm to 5 min after reperfusion (Fig. 2B), and hyperventilation was performed with a tidal volume of 12 ml/kg at a respiratory rate of 13 breaths/min (P_aCO₂, 28 mmHg). His ONSD decreased to 5.1 mm at 30 min after reperfusion (Fig. 2C), and ventilation was adjusted to maintain normocarbia until the end of surgery. He was moved to the surgical intensive care unit after surgery, and then transferred to a general ward without any complications on the seventh postoperative day.