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Monitoring of end‐tidal carbon dioxide partial pressure changes during infrarenal aortic cross‐clamping: a non‐invasive method to predict unclamping hypotension
Author(s) -
Boccara G.,
Jaber S.,
Eliet J.,
Mann C.,
Colson P.
Publication year - 2001
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1034/j.1399-6576.2001.450209.x
Subject(s) - medicine , anesthesia , isoflurane , fentanyl , blood pressure
Background: To assess the variations in end‐tidal CO 2 in response to aortic cross‐clamping and the relationship with systolic arterial pressure (SAP) changes induced by unclamping. Methods: Thirty‐three patients undergoing infrarenal aortic abdominal aneurysm repair by aorto‐aortic prothetic bypass were prospectively studied. All patients were anesthetized with iv midazolam (0.05 mg · kg −1 ), thiopentone (3–5 mg · kg −1 ), fentanyl (5 μg · kg −1 ), pancuronium (0.1 mg · kg −1 ) and the maintainance of anesthesia used was 1–1.5% end‐tidal isoflurane and iv fentanyl. The perioperative management was standardized. End‐tidal CO 2 and SAP were measured 5 min before (Pre‐XAA), 15 min after infrarenal aortic cross‐clamping (XAA), 5 min before (Pre‐UXAA) and immediately after unclamping (UXAA). Results: A total of 16 (48.5%) from 33 patients presented decrease in SAP following aortic unclamping, and 13 out of these patients had arterial hypotension defined as SAP <90 mmHg. End‐tidal CO 2 variation (PreXAA–PreUXAA) induced by aortic clamping was correlated with SAP variation (PreUXAA–UXAA) induced by unclamping (r=0.763; P =0.0001). An end‐tidal CO 2 reduction above 15% after aortic cross‐clamping was found to have a 100% sensitivity to detect a SAP decrease greater than 20% after unclamping, with a 100% specificity and a negative predictive value of 1.0. Complete aortic occlusion duration was not correlated to SAP unclamping variation (ΔSAP). Intraoperative characteristics (fluid loading, hematocrits, urinary output) were comparable, although blood loss was higher in patients experiencing ΔSAP>20%. Conclusions: End‐tidal CO 2 variation monitoring during aortic cross‐clamping may provide a reliable and non‐invasive method to predict unclamping hypotension. When the aortic clamp was released, systolic hypotension (>20%) occurred in those subjects who had a decrease in end‐tidal CO 2 greater than 15% during aortic cross‐clamping.