Anaes SAQs · Vascular anaesthesia
Aortic cross-clamp physiology: clamp-on and clamp-off
Final-examination SAQ for aortic-cross-clamp-physiology.
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ANZCAFRCAEDAICABAFCAI
Prompt
Describe cardiovascular changes at aortic clamp-on and clamp-off and your pharmacological management of each.
Model answer
On (5). ↑SVR/BP, possible ↓CO (17% without vasodilation, 33% in controls), LV strain — controlled vasodilatation (GTN 1 to 2 micrograms/kg/min preserved output), watch ST.[3][4][5]
Off (5). ↓SVR, washout — volume, vasopressor, staged release (taught preparation inside the unclamping scope).[3]
Risk (5). CAD/RCRI (six predictors, derivation 0.5% to 9%); continue chronic beta-blockade, never POISE-style acute loading (death hazard ratio 1.33, stroke 2.17); prepare before each transition.[1][2]
References6ShowHide
- [1]Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation, 1999.PMID 10477528
- [2]Devereaux PJ, Yang H, Yusuf S, et al. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomised controlled trial. Lancet, 2008.PMID 18479744
- [3]Gelman S The pathophysiology of aortic cross-clamping and unclamping. Anesthesiology, 1995.PMID 7717537
- [4]Gelman S, McDowell H, Varner PD, Pearson J The reason for cardiac output reduction after aortic cross-clamping. Am J Surg, 1988.PMID 3128132
- [5]Colson P, Ribstein J, Séguin JR, et al. Mechanisms of renal hemodynamic impairment during infrarenal aortic cross-clamping. Anesth Analg, 1992.PMID 1616156
- [6]Loggi S, Mininno N, Damiani E, et al. Changes in the sublingual microcirculation following aortic surgery under balanced or total intravenous anaesthesia: a prospective observational study. BMC Anesthesiol, 2019.PMID 30611197