Bradycardia during laparoscopic surgery due to high flow rate of CO2 insufflation

provided the original work is properly cited. CC Pneumoperitoneum, using carbon dioxide (CO2), is used to assist laparoscopic surgery by making distension of abdominal cavity and splitting up its content, which improves visualization. However, artificial pneumoperitoneum may cause complications, such as bradycardia and even cardiac arrest, which are originated from increased abdominal pressure and CO2 retention [1]. We experienced severe bradycardia after CO2 insufflation with high flow rate during laparoscopic gynecological surgery. A 59-year-old woman (154 cm and 56 kg), without any remarkable past history except well controlled hypertension, has come to take a laparoscopic colpopexy. Midazolam 2.5 mg was administered intramuscularly, 30 minutes before she transferred to the operation room. On arrival, initial blood pressure (BP) and heart rate (HR) were 120/90 mmHg and 65 beats per minute (bpm), respectively, and peripheral oxygen saturation (SpO2) was 98%. Propofol 120 mg and rocuronium 40 mg were injected for induction. Intubation was done with 7.0 mm endotracheal tube, and tidal volume (9 ml/kg) and respiratory rate were regulated to maintain a normal end-tidal CO2 (ETCO2). Anesthesia was maintained with 50% oxygen and sevoflurane 2 vol% and remifentanil was administered as a 0.05 μg/kg/min infusion, simultaneously. ETCO2 was maintained about 35 mmHg and peak inspiratory pressure (PIP) was 15 cmH2O. Trocar (SAFE PASS TROCARR, Vaxcon co., Incheon, Korea), size of 11 mm, was inserted to 1 cm below the umbilicus to induce pneumoperitoneum. CO2 insufflation was started with an insufflator (Insufflator ML-GX, MGB Endoscope Co. Ltd, Seoul, Korea), and then her BP and HR suddenly decreased to 80/60 mmHg and 42 bpm, respectively. PIP has increased to 20 cmH2O, but ETCO2 and SpO2 did not change. It was thought to be a consequence of peritoneal stretching, owing to pneumoperitoneum, so CO2 insufflation was seized. Remifentanil infusion was stopped and atropine 0.5 mg was injected. Then, BP and HR became 120/80 mmHg and 60 bpm, respectively. CO2 insufflation was started again, but bradycardia and hypotension developed yet again, and BP and HR decreased to 62/32 mmHg and 23 bpm, respectively. Pressure limit of insufflator kept 12 cmH2O during CO2 insufflation, but we found the flow rate of CO2 insufflation was too high (20 L/min). Her vital signs became stabilized again after stopping insufflator and hyperventilation with 100% O2. Flow rate was adjusted to start as 1 L/min and increased to 3 L/min after 2 minutes. While adequate pneumoperitoneum was achieved, vital signs were stable without hypotension or bradycardia. There were no sudden bradycardia or hypotension during surgery and she was transferred to the recovery room without any hazardous event. It is well known that laparoscopic surgery, using CO2 to make a pneumoperitoneum, has risks of pathophysiological cardiovascular changes, such as severe bradycardia, arrhythmia, and cardiac arrest requiring cardiopulmonary resuscitation [1]. Causes of such alteration are known to be associated with vagal-mediated cardiovascular reflex initiated by rapid peritoneum distension due to insufflation or gas embolism [2]. Limiting of intra-abdominal pressure (IAP) below 12-15 mmHg during insufflation is known to be effective to prevent pathophysiological changes of pneumoperitoneum [1]. Even though pressure limitations of insufflator were 12 mmHg in our cases, severe bradycardia has developed after