Peripheral nerve blocks for hip fractures in adults.

BACKGROUND

This review was published originally in 1999 and was updated in 2001, 2002, 2009, 2017, and 2020. Updating was deemed necessary due to the high incidence of hip fractures, the large number of official societies providing recommendations on this condition, the possibility that perioperative peripheral nerve blocks (PNBs) may improve patient outcomes, and the major role that PNBs may play in reducing preoperative and postoperative opioid use for analgesia.

OBJECTIVES

To compare PNBs used as preoperative analgesia, as postoperative analgesia, or as a supplement to general anaesthesia versus no nerve block (or sham block) for adults with hip fracture. Outcomes were pain on movement at 30 minutes after block placement, acute confusional state, myocardial infarction, chest infection, death, time to first mobilization, and costs of an analgesic regimen for single-injection blocks. We undertook the update to look for new studies and to update the methods to reflect Cochrane standards.

SEARCH METHODS

For the updated review, we searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 11), in the Cochrane Library; MEDLINE (Ovid SP, 1966 to November 2019); Embase (Ovid SP, 1974 to November 2019); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCO, 1982 to November 2019), as well as trial registers and reference lists of relevant articles.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) assessing use of PNBs compared with no nerve block (or sham block) as part of the care provided for adults 16 years of age and older with hip fracture.  DATA COLLECTION AND ANALYSIS: Two review authors independently screened new trials for inclusion, assessed trial quality using the Cochrane Risk of Bias-2 tool, and extracted data. When appropriate, we pooled results of outcome measures. We rated the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 49 trials (3061 participants; 1553 randomized to PNBs and 1508 to no nerve block (or sham block)). For this update, we added 18 new trials. Trials were published from 1981 to 2020. Trialists followed participants for periods ranging from 5 minutes to 12 months. The average age of participants ranged from 59 to 89 years. People with dementia were often excluded from the included trials. Additional analgesia was available for all participants. Results of 11 trials with 503 participants show that PNBs reduced pain on movement within 30 minutes of block placement (standardized mean difference (SMD) -1.05, 95% confidence interval (CI) -1.25 to -0.86; equivalent to -2.5 on a scale from 0 to 10; high-certainty evidence). Effect size was proportionate to the concentration of local anaesthetic used (P = 0.0003). Based on 13 trials with 1072 participants, PNBs reduce the risk of acute confusional state (risk ratio (RR) 0.67, 95% CI 0.50 to 0.90; number needed to treat for an additional beneficial outcome (NNTB) 12, 95% CI 7 to 47; high-certainty evidence). For myocardial infarction, there were no events in one trial with 31 participants (RR not estimable; low-certainty evidence). From three trials with 131 participants, PNBs probably reduce the risk for chest infection (RR 0.41, 95% CI 0.19 to 0.89; NNTB 7, 95% CI 5 to 72; moderate-certainty evidence). Based on 11 trials with 617 participants, the effects of PNBs on mortality within six months are uncertain due to very serious imprecision (RR 0.87, 95% CI 0.47 to 1.60; low-certainty evidence). From three trials with 208 participants, PNBs likely reduce time to first mobilization (mean difference (MD) -10.80 hours, 95% CI -12.83 to -8.77 hours; moderate-certainty evidence). One trial with 75 participants indicated there may be a small reduction in the cost of analgesic drugs with a single-injection PNB (MD -4.40 euros, 95% CI -4.84 to -3.96 euros; low-certainty evidence). We identified 29 ongoing trials, of which 15 were first posted or at least were last updated after 1 January 2018.  AUTHORS' CONCLUSIONS: PNBs reduce pain on movement within 30 minutes after block placement, risk of acute confusional state, and probably also reduce the risk of chest infection and time to first mobilization. There may be a small reduction in the cost of analgesic drugs for single-injection PNB. We did not find a difference for myocardial infarction and mortality, but the numbers of participants included for these two outcomes were insufficient. Although randomized clinical trials may not be the best way to establish risks associated with an intervention, our review confirms low risks of permanent injury associated with PNBs, as found by others. Some trials are ongoing, but it is unclear whether any further RCTs should be registered, given the benefits found. Good-quality non-randomized trials with appropriate sample size may help to clarify the potential effects of PNBs on myocardial infarction and mortality.