To the Editor:—
Congratulations to the authors for this excellent study. Some comments: The equal analgesic effectiveness in both epidural analgesia (EDA) and intravenous patient-controlled analgesia (PCA) in this study 1is surprising. Our own and others experiences have demonstrated superior dynamic pain relief during EDA versus intravenous PCA, 2,3also after abdominal aortic surgery. 4The authors have improved analgesic effectiveness of intravenous PCA by a background infusion, with an initial dosage of 80 μg/h fentanyl plus 40 μg on demand. Calculations result in a possible cumulative fentanyl consumption of approximately 2 mg/24 h. The intravenous infusion of fentanyl (75 μ g/h) induces ventilatory disturbances, and in some patients severe respiratory insufficiency or apnea. 5The additional use of a background infusion during intravenous PCA increases the risk of respiratory depression about five-fold. 3Therefore background infusion during intravenous PCA is not recommended for routine postoperative analgesia on the ward, especially in patients with higher risk. 6Increased dosages of opioids may induce sleep disturbances, fatigue, and disability 7, which all are undesired side effects after high-risk surgery. These doubts do not refer to special study conditions, but to routine analgesia on the ward.
Two questions: how high was the fentanyl consumption during intravenous PCA and EDA at days 1, 2, and 3? Did side effects from fentanyl occur?