Abstract
Objective
To evaluate the feasibility of closed-loop blood pressure control during cardiac surgery.
Design
A closed-loop system regulated peroperative hypertension by controlling the infusion rate of the vasodilator nitroglycerin (NTG). The controller consisted of a regulator which was monitored by a supervisory computer program. Mean arterial pressure (MAP) was calculated every 5 s from measurements of the radial artery pressure signal. The regulator calculated an NTG infusion rate with each new MAP measurement. The supervisory computer program monitored the regulator's actions and adapted or overruled the regulator when required.
Setting
The cardiac surgery operating room.
Patients
46 patients who were scheduled for cardiac surgery and who developed peroperative hypertension.
Interventions
Patients were scheduled for either bypass or valve replacement surgery. The closedloop system was used to control hypertension before and after cardiopulmonary bypass. The use of the closed-loop system did not require deviation from the protocol normally used during cardiac surgery. All patients received standard continuous anaesthesia with opioids.
Measurements and results
Initial automatic control was achieved in 9.4 (4.1 SD) min. The percentage of time that MAP remained in a range around the target MAP of ±10 and ±20 mmHg was 74 and 94%, respectively. The mean NTG infusion rate while MAP was within 5 mmHg of target MAP was 1.14 (0.84 SD)μg kg−1 min−1. Target MAP was set between 65 and 90 mmHg. There was a small group of patients (6 out of 46) who did not respond to NTG and required alternative drug therapy.
Conclusions
The controller provided fast and stable control in all patients. The expert knowledge implemented through the supervisory computer program enabled the controller to respond adequately to the rapid changes in arterial pressures commonly associated with cardiac surgery. We conclude that closed-loop control of arterial pressure is feasible not only in the cardiac surgical care unit but also during cardiac surgery.
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References
O'Hara DA, Bogen DK, Noordergraaf A (1992) The use of computers for controlling the delivery of anesthesia. Anesthesiology 77: 563–581
Chitwood WR Jr, Cosgrove DM III, Lust RM, the Titrator Multicenter Study Group (1992) Multicenter trial of automated nitroprusside infusion for postoperative hypertension. Ann Thorac Surg 54: 517–522
Fahmy NR (1978) Nitroglycerin as a hypotensive drug during general anesthesia. Anesthesiology 49: 17–20
Kaplan JA, Jones EL (1979) Vasodilator therapy during coronary artery surgery. Comparison of nitroglycerin and nitroprusside. J Thorac Cardiovasc Surg 77: 301–309
Blom JA (1991) Expert control of the arterial blood pressure during surgery. Int J Clin Monit Comput 8: 25–34
Jansen JRC, Schreuder JJ, Settels JJ, Kloek JJ, Versprille A (1990) An adequate strategy for the thermodilution technique in patients during mechanical ventilation. Intensive Care Med 16: 422–425
Hempelmann G, Piepenbrock S, Seitz W, Karliczek G (1977) Changes in hemodynamic parameters, inotropic state, and myocardial oxygen consumption owing to intravenous application of nitroglycerin. J Thorac Cardiovasc Surg 73: 836–847
Chiariello M, Gold HK, Leinback RC, Davis MA, Maroko PR (1976) Comparison between the effects of nitroprusside and nitroglycerin on ischemic injury during acute myocardial infarction. Circulation 54: 766–773
Endrich B, Franke N, Peter K, Messmer K (1987) Induced hypotension: action of sodium nitroprusside and nitroglycerin on the microcirculation. Anesthesiology 66:605–613
Colvin JR, Kenny GNC (1989) Automatic control of arterial pressure after cardiac surgery. Evaluation of a microcomputer-based control system using glyceryl trinitrate and sodium nitroprusside. Anaesthesia 44: 37–41
Guggiari M, Dagreou F, Lienhart A, Gallais S, Mottet P, Philippon J, Viars P (1985) Use of nitroglycerin to produce controlled decreases in mean arterial pressure to less than 50 mm Hg. Br J Anaesth 57: 142–147
Csongrady A, Ponz-Gonzalez L (1980) Hypotensive anaesthesia in the otorhino-laryngological surgery using nitroglycerine. Anaesthesist 29: 261–265
Isaka S, Sebald AV (1993) Control strategies for arterial blood pressure regulation. IEEE Trans Biomed Eng 40: 353–363
Martin JF, Smith NT, Quinn ML, Schneider AM (1992) Supervisory adaptive control of arterial pressure during cardiac surgery. IEEE Trans Biomed Eng 39:389–393
Mangano DT, Siliciano D, Hollenberg M, Leung JM, Browner WS, Goehner P, Merrick S, Verrier E, Study of Perioperative Ischemia (SPI) Research Group (1992) Postoperative myocardial ischemia. Therapeutic trials using intensive analgesia following surgery. Anesthesiology 76:342–353
Hammond JJ, Kirkendall WM, Calfee RV (1979) Hypertensive crisis managed by computer controlled infusion of sodium nitroprusside: a model for the closed loop administration of short acting vasoactive agents. Comput Biomed Res 12:97–108
Beatty PCW (1993) Software safety considerations in the use of closed-loop patient-connected control systems, Br J Anaesth 71:461
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Hoeksel, S.A.A.P., Schreuder, J.J., Blom, J.A. et al. Automated infusion of nitroglycerin to control arterial hypertension during cardiac surgery. Intensive Care Med 22, 688–693 (1996). https://doi.org/10.1007/BF01709748
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DOI: https://doi.org/10.1007/BF01709748