Does norepinephrine improve haemodynamic parameters compared to phenylephrine in patients with chronic pulmonary hypertension experiencing systemic hypotension during anaesthesia induction?
Norepinephrine is preferable to phenylephrine for treating systemic hypotension during anaesthesia induction in patients with chronic pulmonary hypertension, as it improves the pulmonary-to-systemic pressure ratio without compromising cardiac index.
In this study the effect of phenylephrine and norepinephrine for the treatment of systemic hypotension were evaluated in patients with chronic pulmonary hypertension. When systemic hypotension (systolic arterial pressure < 100 mmHg) occurred following induction of anaesthesia, either phenylephrine or norepinephrine were infused in a random manner to raise the systolic blood pressure by 30% and 50% above baseline values. Norepinephrine decreased the ratio of pulmonary arterial pressure to systemic blood pressure without a change in cardiac index. However, phenylephrine did not increase arterial blood pressure by more than 30% from baseline in one‐third of patients and decreased cardiac index without a significant decrease in ratio of pulmonary arterial pressure to systemic blood pressure. These vasoconstrictors showed different systemic and pulmonary haemodynamic effects in patients with chronic pulmonary hypertension as compared to acute pulmonary hypertension. Norepinephrine was considered to be preferable to phenylephrine for the treatment of hypotension in patients with chronic pulmonary hypertension.
Kwak et al. (2002) studied this question.