Hypertension and perioperative risk

Editor—I read the review1 and associated editorial2 about hypertension with considerable interest and was informed and educated by both. However, my concerns regarding preoperative hypertension do not only extend to the patient, but also to me!

Thus, for a risk-averse anaesthetist, the presence on the list of a patient whose blood pressure is elevated may lead to increased anxiety and push the anaesthetist towards, or over the top of, their Yerkes–Dodson curve.3

I may not be always so risk averse; but I do feel that anaesthesia for elective procedures should be as risk free as possible. Surely the pre-emptive correction of minor degrees of hypertension is more appropriate than the use of invasive monitoring and high dependency care in these cases?

In the light of increasing public awareness of the problems of obesity and alcohol abuse, should advice on weight loss and reduction of alcohol consumption (and their effects on blood pressure4) not only be part of every hypertensive patient's preoperative assessment; but also be issued to them in surgical outpatient clinics?

J. Palmer

Salford, UK


 
Editor—We are most grateful for the opportunity to reply to Dr Palmer's letter. He raises two points. The first is to suggest that the correction of minor degrees of hypertension before surgery is more appropriate than the use of invasive monitoring and high-dependency care in these cases. For admission blood pressures between 120/80 mm Hg and 180/110 mm Hg we were unable to find any evidence of increased perioperative risk. We accept that it is biologically plausible that such blood pressures may confer a small increase in risk. However, this effect is beyond the resolving power of currently available studies, and major cardiovascular risk factors such as heart failure and known ischaemic heart disease are more important indicators of perioperative risk. We have tried to produce guidelines that are pragmatic and clinically useful and, on this basis, we felt unable to recommend deferring surgery to control a risk whose existence we cannot demonstrate.

For admission blood pressures persistently above 180/110 mm Hg, the position is less clear. While there are no data to support an increased incidence of adverse events in this group of patients, the work of Prys-Roberts and colleagues does suggest that patients with very high blood pressures display a greater fall in blood pressure at induction of anaesthesia and are more prone to intraoperative myocardial ischaemia.5 It is for patients with blood pressure elevated to this level that we suggest that anaesthesia and surgery should be deferred where possible to allow the blood pressure to be controlled and, where this is not possible, the use of invasive monitoring and high-dependency care may be appropriate.

We would emphasize that we seek to offer guidelines to aid the clinician, not edicts to ordain patient care. There will certainly be circumstances in which persistently elevated admission blood pressure may, of itself, be a cause for concern. Refractory hypertension in a young patient, suggestive of secondary hypertension, is one such circumstance.

Dr Palmer's second point, on the role of the anaesthetist and surgeon in the primary and secondary prevention of cardiovascular disease, is very well taken. Smoking, obesity and alcohol abuse are difficult problems to tackle but, as physicians concerned with the well being of the whole patient, they certainly fall within our remit.

S. Howell1, J. Sear2 and P. Foëx2

1 Leeds, UK 2 Oxford, UK

References

1 Howell SJ, Sear JW, Foëx P. Hypertension, hypertensive heart disease and perioperative cardiac risk. Br J Anaesth 2004; 92: 570–84[Abstract/Free Full Text]

2 Spahn DR, Priebe H-J. Preoperative hypertension: remain wary? ‘Yes’—cancel surgery? ‘No’. Br J Anaesth 2004; 92: 461–4[Free Full Text]

3 Yerkes RM, Dodson JD. The relation of strength of stimulus to rapidity of habit-formation. J Comparative Neurol Psychol 1908; 18: 459–82

4 Krousel-Wood MA, Muntner P, He J, Whelton PK. Primary prevention of essential hypertension. Med Clin North Am 2004; 88: 223–38[ISI][Medline]

5 Prys-Roberts C, Meloche R, Foex P. Studies of anaesthesia in relation to hypertension. I. Cardiovascular responses of treated and untreated patients. Br J Anaesth 1971; 43: 122–37[ISI][Medline]





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