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We have observed the effect of intubation and incision, as measured by the auditory evoked response (AER) and haemodynamic variables, in 12 patients undergoing hernia repair or varicose vein surgery who received remifentanil as part of either an inhaled anaesthetic technique using isoflurane or as part of a total i.v. technique using propofol. Anaesthesia was induced with remifentanil 1 microgram kg-1 and propofol, neuromuscular block was achieved with atracurium 0.6 mg kg-1 before intubation, and anaesthesia was maintained with a continuous infusion of remifentanil in combination with either a continuous infusion of propofol or inhaled isoflurane. The AER and haemodynamic variables were measured before and after intubation and incision. The effects of intubation and incision on the AER and haemodynamic variables were not significantly different between the remifentanil-propofol and remifentanil-isoflurane groups. However, the study had a low power for this comparison. When the data for the two anaesthetic combinations were pooled, the only significant effects were increases in diastolic arterial pressure and heart rate immediately after intubation; these were not seen 5 min after intubation. There were no cardiovascular responses to incision. There were no significant changes in the AER after intubation or incision.

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Background Limb ischemia is a major complication of femoral venoarterial extracorporeal membrane oxygenation (VA‐ECMO). Use of ankle‐brachial index (ABI) to monitor limb perfusion in VA‐ECMO has not been described. We report our experience monitoring femoral VA‐ECMO patients with serial ABI and the relationships between ABI and near infrared spectroscopy (NIRS). Methods This is a retrospective single‐center review of consecutive adult patients placed on femoral VA‐ECMO between January 2019 and October 2019. Data were collected on patients with paired ABI and NIRS values. Relationships between NIRS and ABI of the cannulated (E‐NIRS and E‐ABI) and non‐cannulated legs (N‐NIRS and N‐ABI) along with the difference between legs (d‐NIRS and d‐ABI) were determined using Pearson correlation. Results Overall, 22 patients (mean age 56.5 ± 14.0 years, 72.7% male) were assessed with 295 E‐ABI and E‐NIRS measurements, and 273 N‐ABI and N‐NIRS measurements. Mean duration of ECMO support was 129.8 ± 78.3 h. ECMO‐mortality was 13.6% and in‐hospital mortality was 45.5%. N‐ABI and N‐NIRS were significantly higher than their ECMO counterparts (ABI mean difference 0.16, 95% confidence interval [CI]: 0.13–0.19, p < .0001; NIRS mean difference 2.51, 95% CI: 1.48–3.54, p < .0001). There was no correlation between E‐ABI versus E‐NIRS (r = .032, p = .59), N‐ABI versus N‐NIRS (r = .097, p = .11), or d‐NIRS versus d‐ABI (r = .11, p = .069). Conclusion ABI is a quantitative metric that may be used to monitor limb perfusion and supplement clinical exams to identify limb ischemia in femorally cannulated VA‐ECMO patients. More studies are needed to characterize the significance of ABI in femoral VA‐ECMO and its value in identifying limb ischemia in this patient population.

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