1 Southampton, UK 2 Giessen, Germany
EditorWe read with interest the article on the incidence, and risk calculation for utilisation, of inotropic support in patients undergoing cardiac surgery.1 The findings of the independent predictors of ventricular dysfunction (presence of chronic obstructive pulmonary disease, age >65 yr, aortic cross clamp time >90 min), would be of no surprise to any cardiac anaesthetist.
More importantly from a scientific point of view, these are essentially the predictors of ventricular dysfunction which have been known for 10 yr or more, as reported in two of the references quoted in the paper.2 3 A further limitation of this report is one common to all scoring systems in medicine. Although such a calculated score is a guide for an individual patients likely treatment needs, it is only a guide and not an absolute predictor.4 Therefore in predicting the need for inotropic support after cardiopulmonary bypass, such a scoring system, using well-known and previously described clinical determinants, is very unlikely to be any better than an average specialist clinicians usual clinical practice.
Timely therapeutic intervention in this context1 is at the time of first attempting to separate the patient from cardiopulmonary bypass. Knowledge of likely need for inotropic support in individual patients is not increased by such a scoring system, and is best managed by a clinician judging the constellation of pre- and intraoperative factors that will determine such, if any, need.
C. Weidmann
M. Herbertson
Southampton, UK
EditorWe are grateful for the opportunity to comment on the interesting letter from Drs Weidmann and Herbertson. We fully agree with their opinion that no scoring system can replace clinical experience. However, as we pointed out,1 knowledge of readily determined clinical risk factors should be used to increase the vigilance even of a specialist clinician.
The differences in the reports of Butterworth2 and Royster3 have been extensively discussed. Both focused mainly on cardiac variables. But, in addition, we have shown that concomitant pathology, such as chronic obstructive airway disease, can be a risk factor for the use of inotropes.1
It is our opinion that failure to wean off bypass should be a rare event not only for pathophysiological, but also for economic reasons. Effective treatment strategies should be initiated before first attempting to separate the patient from cardiopulmonary bypass.
A. Jünger
Giessen, Germany
References
1 Müller M, Jünger A, Bräu M, et al. Incidence and risk calculation of inotropic support in patients undergoing cardiac surgery with cardiopulmonary bypass using an automated anaesthesia record-keeping system. Br J Anaesth 2002; 89: 398404
2 Butterworth JF, Legault C, Royster Rl, Hammon JWJ. Factors that predict the use of positive inotropic drug support after cardiac valve surgery. Anesth Analg 1998; 86: 4617[Abstract]
3 Royster RL, Butterworth JF, Prough DS, et al. Preoperative and intraoperative predictors of inotropic support and long term outcome in patients having coronary artery bypass grafting. Anesth Analg 1991; 72: 72936[Abstract]
4 Weightman WM, Gibbs NM, Sheminant MR, et al. Risk prediction in coronary artery surgery: a comparison of four risk scores. Med J Aust 1997; 166: 40811[ISI][Medline]