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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
Two types of specialist drug used to treat shock neither increased or reduced deaths of critical care patients. Inotropes and vasopressors are two types of drug that are used to increase and maintain blood flow in patients who are severely ill with critically low blood pressure - a condition known as shock.
The drugs are accepted care for severe shock but there has been concern that they may also increase mortality in some situations and their use in less severe shock has been debated. The findings provide general reassurance about current critical care practice, in that these commonly used drugs do not cause extra deaths. Their use, however, does carry a cost in terms of the drug itself and additional monitoring to adjust dosage.
This review studied adult patients across a range of critical care settings, and included a large number of trials. However, more specific research is needed to look at the beneficial effects of individual drug treatments and their use in treatment of different classes or severity of shock.
Why was this study needed?
Critical care is expensive and also subject to audit (for example, the National Cardiac Arrest Audit) to ensure the best outcomes are achieved for patients and the best use is made of NHS resources. This systematic review collated the findings of trials on two types of drugs, inotropes and vasopressors, which are used in critical care to improve and maintain the circulation in the short term in people with life-threatening conditions (see Definitions). Previous research has suggested that they may be associated with adverse outcomes, in particular an increased risk of mortality. Individual trials on these drugs have involved relatively few deaths, so a review was needed to aggregate these outcomes.
What did this study do?
This large systematic review included 177 randomised controlled trials of variable size in which a total 28,280 people were randomly assigned to receive either one of these drugs, or alternatively placebo or best available treatment. Each trial compared survival between the two groups. Fifteen different vasopressor and inotropic drugs were used across the trials and the conditions leading to shock varied, including heart failure, sepsis and complications of major surgery. The length of time over which mortality outcomes were assessed ranged from in-hospital, to up to one month, to up to one year. The review was carried out to a high standard and drew on findings from a large number of moderate quality trials. The settings and underlying conditions treated in these trials varied as did the drugs (which had different mechanisms of action). A wide range of exploratory sub-analyses were conducted to look at these subgroups in detail but no clear signal was found to allow researchers to apply the findings or draw particular conclusions for specific circumstances.
What did it find?
- Overall there was no significant difference in the death rate for patients who received a vasopressor or inotropic drug (30.3%) compared with patients who did not (30%), (risk ratio [RR] 0.98, 95% confidence interval [CI] 0.96 to 1.01).
- Levosimendan was the only individual drug that had a significant effect on mortality. Across 48 trials, fewer people who took this drug died (11%) compared with people in the same trials who did not (12.4%) (RR 0.80, 95% CI 0.68 to 0.94). This drug was used in 28% of all trials but is not available for use in the UK.
- Looking at trials with different follow-up times, inotropes or vasopressors appeared to have a significant effect on mortality assessed one month after treatment. In 35 trials one-month mortality was reduced in the treatment groups (20.2%) compared with the control groups (26.1%) (RR 0.75, 95% CI 0.57 to 0.98). It is not clear if this outcome was specified by the researchers before starting the trial.
What does current guidance say on this issue?
There is no guidance focussing on the broad topic of using vasopressors and inotropes in critical care. However some guidelines do address aspects of the topic, such as Intensive Care Society standards on treatment after cardiac arrest (2008) or upcoming NICE guidance on treatment of sepsis and septic shock due to be published in July 2016.
What are the implications?
Inotropic and vasopressor drugs are in widespread use for patients in critical care. The findings of this review may reassure practitioners that there is no evidence that their use is associated with increased mortality risk as has been previously suspected, but neither was any substantial reduction in mortality shown.
The trials had some limitations which may reduce the applicability of the findings. They encompassed a wide range of drugs and clinical settings. The review did not find that inotropes or vasopressors differentially affected mortality across the different groups of people examined, such as those with heart failure, cardiac arrest or having major surgery. However, this does not remove the possibility that there may be some difference in effectiveness or safety depending on the drug used or the shock condition.
Some clinicians may consider these drugs essential for treating very ill patients with circulatory failure. As such the trial participants may predominantly represent those where the condition wasn’t thought immediately life threatening and where the treatment approach wasn’t clear. This may limit the applicability of the findings to all people with shock.
Citation
Belletti A, Castro ML, Silvetti S, et al. The effect of inotropes and vasopressors on mortality: a meta-analysis of randomized clinical trials. Br J Anaesth. 2015;115(5):656-75.
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