Anest. intenziv. Med. 2011;22(5):266-271

The mechanism of hypotension with intravenous paracetamol in the critically illIntensive Care Medicine - Original Paper

Krajčová Adéla¹, Matoušek Vojtěch¹, Duška František^1,2,3,*

¹ 3. lékařská fakulta Univerzity Karlovy, Praha

² Klinika anesteziologie a resuscitace Fakultní nemocnice Královské Vinohrady, Praha

³ Ústav biochemie a molekulární biologie 3. LF UK, Praha

Objective:
To elucidate the mechanism of hypotension caused by intravenous administration of paracetamol (acetaminophen) in the critically ill.

Design:
Prospective, observational, cross-over study.
Setting:
Intensive Care Unit, University Hospital.

Methods:
Mechanically ventilated critically ill patients monitored by PiCCO who were concurrently administered i.v. paracetamol were eligible for the study. We recorded the haemodynamic indices, the core and peripheral temperatures continuously for 3 hours after the administration of paracetamol or a control drug known not to influence the haemodynamics.

Results:
We included 6 subjects in whom we recorded 48 episodes of i. v. paracetamol administration and 35 episodes of control drug administration. The haemodynamic parameters were not different at baseline (p = NS) and the administration of the control drug did not result in any changes in the haemodynamics. After i. v. paracetamol administration, mean arterial pressure dropped by 7% (p < 0.001) with a nadir in the 19^th minute, caused by a small but statistically significant decrease in both cardiac output and systemic vascular resistance by 5% (p < 0.001). The haemodynamic response to paracetamol is inter-individually variable and dependent on body temperature. In pyrexial patients, paracetamol has negative inotropic effects (cardiac output decreases by 10%), whilst in afebrile subjects, vasodilation predominates. In pyrexial patients we observed a narrowing of the gradient between the core and skin temperatures suggesting skin vasodilation, but this was not followed by changes of the systemic vascular resistance.

Conclusion:
Intravenous paracetamol alters the haemodynamics in a subset of critically ill patients by decreasing both the cardiac output and systemic vascular resistance. Vasodilation is more pronounced in afebrile subjects, whilst a negative inotropic effect predominates in pyrexial patients.

Keywords: paracetamol; acetaminophen; adverse effect; hypotension; systemic vascular resistance; cardiac output

Received: June 23, 2011; Accepted: September 20, 2011; Published: October 1, 2011  Show citation