No coronary artery occlusion in septic shock: Isoproterenol infusion should not be discouraged.

Dear Editor,

in their relevant letter, Dr Wiwanitkit pointed out important limitations about the use of isoproterenol: these authors should be commended for their input to our research. Indeed, in animal models of coronary occlusion, isoproterenol administration augmented infarct size [1], suggesting that the use of isoproterenol in patients with coronary artery occlusion should be discouraged, probably in favor of the use of dobutamine in the same patients [2]. However, in those models, isoproterenol was used as repeated boli of 0.15 mg/kg (i.e. 9 mg for 60 kg) in non-resuscitated animals, whereas in our patients we infused continuously a maximal dosage of 0.5 mg/h after well-conducted resuscitation.

Patients with septic shock do not suffer from coronary occlusion. Several experimental models suggest that septic shock induces an even increased coronary flow [3]. In addition, beta-adrenoreceptors are desensitized in patients with sepsis [4], supporting the need to introduce the most powerful beta-adrenergic inotrope in selected patients developing a septic acute heart failure [4, 5]. Finally, to date, both experimental models and cohorts of patients did not reveal harm associated with the use of isoproterenol in this indication [6, 7].

In conclusion, inotropes should be carefully used in few, selected patients. The harmful effect of isoproterenol in animals with coronary occlusion, however, should not discard its potential role in septic shock.