Inhaled analgesia – where is the evidence?
In prehospital emergency care, the evidence of underuse of analgesics in the face of valid indication (oligoanalgesia) remains a problem. Where issues around vascular access contribute to oligoanalgesia, inhaled analgesics may provide a solution; however, the literature around the safety and efficacy of such drugs is limited. This systematic review aimed to establish the knowledge base for the effectiveness and safety of inhaled analgesics in prehospital emergency care.
The population, intervention, comparison, and outcomes (PICO) items for this systematic review were:
- Population: Adult patients with acute pain in the prehospital emergency care setting
- Intervention: Inhaled analgesics
- Comparison: Other analgesics or placebo
- Outcomes:
- Primary outcome: pain reduction
- Secondary outcomes: speed of onset; duration of effect; relevant adverse events; safety issues for healthcare providers.
From an initial 3792 reports found in the search, only seven papers (including 56 535 patients in total) comparing inhaled agents (methoxyflurane (MF) and nitrous oxide (N2O)) to other drugs or placebo were deemed eligible for inclusion. The certainty of the evidence was judged to be of low or very low quality according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria, so, to a certain extent, the questions remain unanswered. This systematic review identified that MF and N2O are safe and may have a role in the management of pain in the prehospital setting. They established low-quality evidence to support MF as a short-acting single analgesic or as a bridge to IV access and the administration of other analgesics. They also identified potential occupational health issues regarding the prehospital use of N2O. What is fascinating about this systematic review is the dearth of high-quality evidence available to support interventions that are carried out routinely in many established prehospital emergency settings. It is an area that needs further exploration – PhD anybody?
When the focus is too much on POCUS
Adding gizmos and gadgets to the paramedic armoury is always exciting, but consideration needs to be given to the laws of unintended consequence. Prehospital point-of-care ultrasound (POCUS) is emerging as a tool to rapidly and accurately assess unstable patients. However, can its use lead to distraction, reduced situational awareness and the neglect of other crucial instruments in an already-demanding emergency medical service environment?
This study used simulation to examine the influence of POCUS on situational awareness by studying the degree to which eight HEMS physicians were distracted from the patient monitor. The participants were instructed that their patient was a motorcyclist who had been involved in a traffic accident (motorcyclist vs car) and that the patient had already been monitored in the helicopter. The patient was initially haemodynamically stable but complained of pain in the left hemithorax. The participant was instructed to perform an ultrasound examination during transport and was asked to report all subjectively perceived pathological findings to the observer present in the room. Within 2 minutes of the session beginning, the patient desaturated (simulated SpO2 from 100 to 88%), as displayed on the patient monitor. Researchers noted the time until the drop in saturation was recognised by participants. The patient monitor did not emit an audible alarm to attract the participant's attention, which was normal in a flight scenario.
In 75% of cases, the decreased oxygen saturation went unnoticed during the test. The gaze distribution of the two groups differed, with the group that recognised the deterioration focusing longer on the patient monitor (7.8% (95% CI 5–10.7) vs 0.1% (95% CI 0–0.3), p=0.124).
This was a very small simulation study so is not open to wider extrapolation. However, it is of interest given the growing number of competing demands for attention in prehospital emergency care. It is reasonable to suggest that just teaching a new procedure such as POCUS is not sufficient and that efforts to mitigate distractions and optimise the use of additional tools need to be considered.