A pain in the hip: the under-used potential of fascia iliaca compartment block in the prehospital setting

Fascia iliaca compartment block (FICB) is a technique for flooding the fascia iliaca compartment with local anaesthetic, resulting in blockade of the femoral and lateral cutaneous nerves. It has demonstrated potential as an alternative to opiates for perioperative pain management in shaft or neck of femur (NOF) fracture patients, with a favourable side effect profile.¹

Evidence for FICB in the prehospital setting is comparatively scarce, but it appears to be feasible, safe and effective when administered by emergency medical services (EMS) for proximal femoral fractures, with the majority of evidence from studies of emergency physicians, anaesthetists or nurses.² FICB was adopted into Aotearoa New Zealand EMS clinical practice guidelines for suspected femoral neck or proximal shaft fractures in late 2020.³

Despite promising results from a small trial (n=24) in Australia and a feasibility study in Wales,⁴ we are not aware of any previous studies looking at real-life implementation of paramedic-administered FICB in the prehospital setting. This study aims to describe characteristics and pain outcomes for patients who were administered FICB by Hato Hone St John (HHStJ) in a 1-year period and compare them with a cohort with similar injuries and no FICB.

Methods

HHStJ is New Zealand’s largest EMS provider, covering 90% of the country’s population. In September 2020, FICB training began for specialist (postgraduate-qualified) paramedics. The anatomically guided, tactile loss of resistance technique may be used to administer 30ml (patients weighing <60kg) or 40ml (patients weighing >60kg) of 0.375% ropivacaine to patients with severe pain associated with clinically obvious fractured NOF or proximal shaft of femur in line with clinical practice guidelines.³ Guidelines recommend FICB for patients whose pain is not adequately controlled by an opiate, offering FICB as an alternative to additional medicinal analgesia for this patient group.³

The Aotearoa New Zealand Paramedic Care Collection (ANZPaCC) combines EMS patient and incident data and is linked to Ministry of Health – Manatū Hauora data using National Health Index numbers.⁵ Within ANZPaCC, we identified emergency call incidents attended by HHStJ between 1 May 2022 and 30 April 2023 with International Classification of Diseases 10th revision (ICD-10) codes indicating a fracture of the neck or proximal shaft of the femur (Appendix Table 1). Patients with Glasgow Coma Scale scores ≤12, a clinical impression of major trauma, clinical status indicating immediate threat to life, aged under 12 years, not transported by HHStJ or who declined assessment by ambulance staff were excluded. The patient’s home address was used to estimate relative socio-economic deprivation using the New Zealand Index of Deprivation 2018 (NZDep2018),⁶ and incident location was categorised by rurality using the Geographic Classification for Health.⁷ Pain was patient-reported on a numerical scale from 0 to 10. Transport time was in minutes from scene of the injury to arrival at a hospital. Ministry of Health – Manatū Hauora gender, ethnicity and ICD-10 diagnosis codes were used (Appendix Table 1). FICB cases were checked against a list of reportable events to identify auditor or crew-reported adverse events, and were manually screened to identify further possible safety concerns.

Statistical analysis used SPSS v29. Patient characteristics were compared between FICB and comparison groups using Independent Samples median tests (continuous variables) or Chi-squared tests (categorical variables). The primary outcome was pain score reduction, calculated as the difference between the first and last score recorded for the incident and compared between FICB and comparison groups using linear regression, with the final model adjusted for initial pain score, gender and rurality. This study was approved by the Northern B Health and Disability Ethics Committee (Aotearoa New Zealand, Paramedic Care Collection [ANZPaCC], 2022 FULL 13415).

Results

There were 3,860 incidents in the time frame potentially eligible for FICB. Patients receiving FICB were predominantly female (73%), aged 80 years or older (71%), of European ethnicity (92%) and injured in urban areas (79%) (Table 1). A higher proportion of FICB patients were female, but they did not differ from other patients on ethnicity, age or neighbourhood deprivation score (Table 1). Distribution across urban/rural locations differed between FICB and comparison patients, with higher proportions of the FICB group injured in Urban 2 and Rural 1 areas (Table 2). FICB patients more often had initial pain scores in the severe range (74% vs 46%).

View Table 1–2.

No adverse events were reported by crews or auditors for any FICB patient. Based on manual screening of patient records, one patient was identified as experiencing a tonic-clonic seizure shortly after ropivacaine administration. The patient recovered without intervention and is not known to have experienced any further adverse outcomes.

Final pain scores were missing for 1,105 patients. For those with complete pain scores, final scores were 3.2 points lower than initial pain scores, on average. FICB patients had a greater mean reduction in pain score than comparison patients (Table 2), which remained significant after adjustment for initial pain scores, gender and rurality (R²=.38, F[1,11]=150.2, p<.001).

Discussion

This study adds to evidence for safe and effective prehospital use of FICB to manage pain for NOF fracture. Patients who received FICB reported a greater reduction in pain between ambulance arrival and handover to hospital care, even when controlling for higher initial pain scores. Most FICB patients (94%) experienced a reduction in pain, with 21% reporting no pain on handover. These results are consistent with previous literature on FICB indicating favourable outcomes in emergency department, perioperative and prehospital settings.^1,4,8 Different proportions of patients by rurality likely reflect less need in urban areas close to hospitals and less availability in the most rural areas.

One patient experienced a seizure, a documented symptom of ropivacaine toxicity,⁹ within minutes of FICB administration. Two similar incidences were reported in a recent meta-analysis including 257 FICB in the prehospital setting.⁴ Though rare, training should prepare clinicians for such events.

Only 3.6% of patients with eligible fractures were treated with FICB in this study. Though we were unable to confirm that the comparison patients were suitable candidates for FICB with this dataset, the proportion has reduced from 5.6% in the first year after the skill was introduced in clinical practice guidelines.¹⁰ Changes to the way paramedics trained to perform FICB are deployed has likely resulted in fewer trained clinicians in ambulances tasked to patients with isolated femoral fractures. EMS often must choose between requesting and waiting for trained personnel to perform the procedure or prioritising prompt transport to definitive treatment. Welsh paramedics also noted that painful repositioning of the patient was sometimes needed to prepare for FICB, whereas intravenous medications could more easily be administered prior to extrication, after which obvious benefits of FICB were less apparent.¹¹

Perioperatively, FICB has been associated with improved pain management for up to 48 hours.¹ With increasing lengths of time in emergency departments for hip fracture patients in New Zealand,¹² the value of prompt arrival at hospital should be considered against the potential of prehospital interventions to have longer-term benefits for patients while they are awaiting further assessment or treatment after handover from ambulance care.

This study was limited by the use of administrative data, with a high rate of missing pain scores, particularly in the comparison group. Initial pain score was captured at arrival on scene and may not reflect the pain level used for treatment decisions, which takes into account the need for patient mobilisation or transfer. Other potential benefits of FICB compared with other pain management that we were not able to examine in this study include lower morphine consumption and related nausea,^1,8,13 fewer complications,⁸ lower cost⁴ and better control of dynamic pain in particular.¹³ Further research with frontline staff and longer patient follow-up is needed to understand whether FICB use should be promoted in the prehospital environment.

View Appendix.