Pressure monitoring: The evidence so far

Nerve injury is a relatively rare but devastating complication of peripheral nerve blockade (PNB). Monitoring injection pressure during PNB is one method advocated to prevent injury by detecting needle tip placement in a noncompliant position (intraneural or abutting the epineurium). Animal studies show that gross neural damage and clinical injury are associated with injection pressures exceeding 15-20 psi. In contrast, pressures <15 psi are associated with an extraneural needle tip position and no histologic or clinical injury. Injection pressure monitoring has been shown to prevent injection against the brachial plexus roots or femoral nerve during peripheral nerve block. Multiple methods are available to monitor injection pressure, and most of them are inexpensive and easy to use. Large-scale registry database or pragmatic trials are indicated to show that injection pressure monitoring reduces injury in a patient setting.