Repeated assessment of arterial blood gas is diffi cult immediately after anesthesia induction because anesthesiologists are preoccupied with several tasks such as airway management, blood pressure regulation, and patient positioning. In practice, however, measuring the partial pressure of arterial carbon dioxide (PaCO2) and attaining normocapnia in real time is challenging, especially immediately after anesthesia induction. 2,3 Alternatively, hypercapnia might cause a decline in the cerebral blood fl ow by “intracerebral steal” because the collateral network of vessels is in a state of maximal vasodilation. 1 Hypocapnia causes cerebral vasoconstriction and could result in cerebral ischemia. Goal of intraoperative ventilation was to provide normocapnia for patients at risk of cerebral ischemia such as those with Moyamoya disease. The simple equation using gender and a multiple of body weight yields similar predictive performance to the Radford nomogram. The Radford nomogram overestimates MVnorm in modern, balanced anesthesia. In the validation group (n = 26), the mean bias of this simple equation was 224 mL/min (95% limits of agreement, -1,264–1,712 mL/min). The equation developed using data from the development group (n = 52): required minute volume (mL/min) = 85 × body weight (kg) in male patients and 70 × body weight (kg) in female patients. The Radford nomogram tended to overestimate MVnorm with a mean bias of 560 mL/min (95% limits of agreement, -848–1,968 mL/min). Furthermore, we developed and validated a simple equation predicting MVnorm based on gender and a multiple of body weight, using a split-sample validation technique. We examined the agreement level between the estimated minute volume using the Radford nomogram and MVnorm using the Bland–Altman analysis. We defi ned MVnorm as the median of all values of the minute volume during normocapnia (estimated PaCO2: 38–42 mmHg). ![]() This single-center retrospective study enrolled 78 patients (age ≥ 18 years) undergoing cerebral revascularization for Moyamoya disease. This study aims to investigate the performance of the Radford nomogram in patients undergoing general anesthesia and derive a simple equation to estimate the minute volume required to attain normocapnia (MVnorm). The Radford nomogram, an old mathematical chart device to estimate the required ventilation for maintaining normocapnia, remains unvalidated in patients undergoing modern, balanced anesthesia.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |