Naloxone may improve blood pressure in people who are in shock but more trials are needed to show whether this reduces deaths

When people go into shock, their blood pressure drops and may be too low to sustain life. One theory about the cause of this is the effect of the opiates that the body produces after major blood loss or trauma. Naloxone is a drug that counteracts the effects of opiates. It has been tried as a treatment to reduce the impact of shock. This review of trials found that giving naloxone to people in shock improves their blood pressure. It is not clear whether or not this improves their overall condition or reduces their chances of dying. More trials are needed.

Authors' conclusions: 

Naloxone improves blood pressure, especially mean arterial blood pressure. However, the clinical usefulness of naloxone to treat shock remains to be determined and additional randomized controlled trials are needed to assess its usefulness.

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Background: 

There is pre-clinical evidence, involving several animal species, suggesting that opioid peptides play a role in the physiopathology of shock (endotoxic, hypovolemic, cardiogenic, spinal, anaphylactic). Many case reports have suggested that naloxone (an opiate antagonist) might be an effective treatment for shock in humans, but others have not supported such a point of view. This controversy led us to undertake a meta-analysis of the available evidence on the efficacy of naloxone as a treatment measure for shock in humans.

Objectives: 

To evaluate the effectiveness and safety of naloxone in human shock and to estimate the methodological quality of the clinical trials.

Search strategy: 

We searched the Cochrane Injuries Group Specialised Register, CENTRAL (The Cochrane Library), MEDLINE (Ovid SP), PubMed, EMBASE (Ovid SP), ISI Web of Science: Science Citation Index Expanded (SCI-EXPANDED), and ISI Web of Science: Conference Proceedings Citation Index-Science (CPCI-S) (to December 2008). In order to identify further studies the reference lists of all included papers were examined and the primary investigators of eligible studies were contacted.

Selection criteria: 

Randomized controlled trials evaluating naloxone in human shock, regardless of the patient's age (adult, child, or neonate).

Data collection and analysis: 

Three independent review authors extracted data on study design, intervention, outcomes, and methodological quality.

Main results: 

Three independent readers reviewed 120 publications and selected six clinical trials. Overall agreement on study selection was perfect (concordance: 100%). The meta-analysis includes six studies involving 126 patients with septic, cardiogenic, hemorrhagic, or spinal shock.

Naloxone therapy was associated with statistically significant hemodynamic improvement (odds ratio 0.24; 95% confidence interval (CI) 0.09 to 0.68). The mean arterial pressure was significantly higher in the naloxone groups than in the placebo groups (weighted mean difference +9.33 mm Hg; 95% CI 7.07 to 11.59). No heterogeneity was found for this outcome. The death rate was lower in the naloxone group (odds ratio 0.59; 95% CI 0.21 was 1.67) but this was consistent with the play of chance. A significant heterogeneity was detected for the latter outcome (P < 0.05).

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