Modification of the cardiovascular responses to general anaesthesia by transdermal nitroglycerine - abstract

ABSTRACT

Low dose, transdermal nitroglycerine (TD-NTG) in a "nitropatch" formulation was used in an attempt to ameliorate the hypertensive, tachycardiac response to tracheal intubation. Observations were also made to elucidate whether TD-NTG 5 mg has any effect on the subsequent period of general anaesthesia and recovery. TD-NTG 5 mg patches were applied to ten young, healthy patients with ten similar patients as controls. Premedication, induction and the first four minutes of anaesthesia were standardized. Systolic (SBP), diastolic (DBP) and mean (MAP) arterial pressures along with heart rate (HR) were measured at constant intervals. Rate-pressure product (RPP), as an indicator of myocardial oxygen consumption, was derived for each set of measurements. There was a short-lived, significant (p<0.05) rise in all variables in both groups, during intubation. This rise was significantly lower for all variables (except HR) between the two groups. The increase in HR was similar between the groups. There were no significant differences in the pre-induction or recovery-room measurements between the groups. No gross differences were noted during the course of anaesthesia after intubation. The only side-effect noted was slight headache in TD-NTG patients. TD-NTG patches are a useful addition to the anaesthetic armoury of drugs to control blood pressure during intubation. Their removal before induction from patients using them for the control of angina must be carefully considered in the light of the present study's findings of no adverse effects during general anaesthesia (AU)