Hypothesis: The use of ultrasound in regional anesthesia decreases the odds of complications
Methods: A multicenter database (GNRA) of 25 German hospitals was queried for patients aged 0-100 years who received a peripheral nerve block. Patients were excluded from the cohort if data was missing regarding use of ultrasound, demographics, or complications. Of the initial query of ~49,000 patients who received a nerve block, the final cohort was ~27,000. The cohort was divided into groups of patients where ultrasound was used alone vs. ultrasound and nerve stimulation vs. nerve stimulation alone. Propensity score matching was used to compare groups. Complications were considered vascular puncture, multiple skin punctures and unintended paresthesia. Secondary outcome was occurrence of local anesthetic systemic toxicity (LAST)
Results:
With ultrasound alone (US) vs. nerve stimulation (NS) alone, the ultrasound group had a statistically significant decrease in incidence of multiple skin puncture (OR 2.2 NS alone) and vascular puncture, but an increased incidence of paresthesia (OR 0.3 NS alone).
Combination US and NS vs. US alone, the combination group had increased incidence of multiple skin puncture, decreased risk of paresthesia and no change in incidence of vascular puncture
Strengths: Question was clinically relevant with well-defined primary endpoints, large sample, and use of propensity scoring
Weaknesses: After matching, majority of data originated from two hospitals and largely related to lower extremity peripheral nerve blocks. Furthermore, there was no data regarding block efficacy which is perhaps the most central clinical question.
Key Point: Use of ultrasound alone reduced the odds of vascular and multiple skin punctures. However, the sole use of ultrasound increased the odds of paresthesia.