RSI Indications & Decision Making

Introduction– decision-making around the indication of pre-hospital intubation is often predetermined by the emergency nature of the patient’s presentation. However, the risk versus benefit balance may well differ from that which many clinicians would be used to within the hospital setting. A set of predetermined indications for which the benefit is felt to outweigh the risks of performing intubation in a relatively uncontrolled environment is helpful in driving decision-making for these patients.

With this in mind, this presentation will review the indication for anaesthesia in the pre-hospital environment. And we will highlight how that might differ from the hospital environment. We will also consider how patient factors and environmental factors might affect the decision-making and subsequent delivery of anaesthesia. The following are widely accepted indications for pre-hospital RSI. Actual or impending airway compromise– this is relatively self-explanatory. If a patient has an airway issue that requires an emergency intervention, this should happen at the earliest opportunity. This indication also covers those patients such as burns patients, where the earlier an airway intervention occurs, the more likely it is to be successful.

It may well be the case that a pre-hospital anaesthesia presents the only viable opportunity to intervene in a patient’s airway management.

Ventilatory failure– this indicator refers to the patient who requires intubation to overcome failure to either oxygenate or ventilate effectively as a result of a burden of injury or illness. A common marker for this in the pre-hospital environment is failure to maintain oxygen saturation despite maximised oxygen therapy. The lack of blood gas analytics mean that physical assessment of the patient is critically important.

Unconsciousness– the assessment of unconsciousness requires an accurate GCS assessment, but this is a dynamic assessment tool, and the score may change with time. The motor component is felt to hold the most weight with regard to objective level of consciousness. But assessment of the effect of conscious level on requirement for intubation must be conducted on a patient-by-patient basis and not simply be based on a single GCS score.

Patients who are unmanageable or severely agitated after head injury– the agitated patient following head injury presents both a clinical and safety issue for the pre-hospital clinician. Initially, sedation may be used to gain control, but this is not without risk. Often the safest option for both patient and clinician is for the patient to be anaesthetised prior to transport to hospital. This not only allows safe transport, but may well improve clinical care during this phase, allowing appropriate airway management and secondary neuroprotection.

Anticipated clinical course– this is the patient anticipated to need an RSI before arriving at hospital due to likely deterioration en route or for whom intubation is likely to become more challenging due to progression of the clinical condition. It is therefore potentially safer to perform an RSI at an earlier stage in such cases. This is not the patient who will need RSI in the ED in order to allow a CT to be done. This is a common misunderstanding of this indication.

Humanitarian need– this indication is in place because there may well be an inability to control pain from polytrauma and burns without recourse to anaesthesia at levels that require intubation.

Patient considerations– in the pre-hospital setting, there is a requirement to consider how patient-specific variables might affect the clinician’s ability to deliver a safe anaesthetic. It can be assumed that whilst this has an impact on the risk-benefit considerations, on many occasions, the need for anaesthesia and intubation is emergent and will necessitate the clinician to manage the risk rather than not continuing with the intervention. This section will review common patient considerations and briefly review mitigations that might be significant.

Extremes of age can present a significant issue to the pre-hospital condition. Both frailty as a result of advanced age and the complexity of a paediatric patient can challenge the clinical team when these patients require anaesthesia in the pre-hospital setting. The frail elderly patient is often physiologically more complex and multi co-morbid in comparison to their younger, more robust counterparts. Medical conditions and the accompanying polypharmacy is common. The clinician should consider these factors in drug dosage calculations. Often it may be prudent to reduce doses as an induction to prevent hypotension. This is especially true for opioid medications, such as fentanyl, to which the elderly seem to be more sensitive, requiring roughly half the doses to have similar effect.

The clinician should also be aware of the likely delayed onset of muscle relaxants due to reduced muscle blood flow. Drug clearance times are also likely to be delayed in this patient group. Slow titration of analgesia and sedative medications may prevent significant side effects in the awake patients.

It is also important to consider other things such as DNR status and triage, as it may not be appropriate to intervene in all patients, depending on their presentation. However, it is clear that the emergent pre-hospital setting is not the place to make significant quality of life or prognostic decisions. The clinician should also be aware of the importance of careful patient handling and temperature management, with the less robust, frail patient more at risk of iatrogenic injury and hypothermia.

Infants and children can present challenge around decision-making and the risk-benefit of interventions. Typically, about 10% of patients seen by HEMS services are paediatric, and the rate of significant interventions such as RSI is low, around 5% to 10%. Many pre-hospital clinical teams will not have regular paediatric anaesthetic experience, and this should, and does, affect the risk-benefit of pre-hospital anaesthesia. The decision to transfer a patient with simple airway management plan rather than undertaking anaesthesia may be informed by the team’s level of experience. The clinical team should make efforts to improve their exposure by attending theatre [INAUDIBLE] and other supportive clinical settings, where possible.

Some mitigations can be provided by using age/weight related guides to enable the clinician to focus on clinical care rather than dose calculations and finding the most appropriate equipment. The dosage should be checked despite this, and age and size are often not completely related. It might be appropriate to check with the parent whether they have a recent weight or what age clothes the patient is wearing as a guide.

Obesity– whilst in the hospital setting, there are often mitigations for anaesthesia in the obese patient, these are often more difficult to achieve pre-hospitally. Even simple interventions, such as ramping, they require more involved logistics and consideration of risk versus benefit. The significantly obese often will prove difficult to wrap on a standard ambulance trolley, and this would involve removal of any scoop device used to move a patient from the floor. Access to specialist ramping pillars is not standard, and there is no recourse to awake intubation or more advanced airway devices. Enabling some ramping with available pillows and blankets alongside head-up positioning to reduce weight on the chest may provide some mitigation.

The dosing of drugs and ventilation strategies should reflect the problems associated with obesity. The drugs normally used in the pre-hospital setting should be dosed to ideal body weight or, in the case of fentanyl, lean body weight. If giving midazolam, then some increase in dose towards actual body weight if giving a single bolus should be considered. Pre-oxygenation and ventilation strategies must take into account reduced FRC and increased oxygen consumption. PEEP and apnea ventilation should be considered.

Anticipation and preparation for a potentially difficult airway are crucial to avoid unnecessary difficulty. Immediate access to adjuncts and supraglottic airway devices may provide temporising measures in can’t intubate scenarios. Equipment for front of neck access should also be prepared where difficulty is anticipated. Repeated attempts to intubate a patient who can be ventilated by face mask or supraglottic airway device should be limited and follow considered changes to the technique or equipment being used. Pre-hospital difficult and failed airway drills will be covered in much more detail later in the course. In some cases, the degree of anticipated difficulty may be so high that the balance of risk and benefits favours compares to hospital for advanced airway management rather than induction of pre-hospital anaesthesia.

Logistical Considerations– logistical considerations and variables are also important to consider in decision-making and delivery of pre-hospital anaesthesia. Environment– the nature of pre-hospital work means that controlling the environment will reduce cognitive stress. Reducing unnecessary noise and interruptions at the time of undertaking critical interventions is important. There should be a defined plan of how to achieve this. Often, mitigations for conditions such as bright sunshine or inclement weather can be achieved by careful consideration of the area in which anaesthesia is to be delivered– for example, having backs to the sun for the intubator and assistant or moving to a more distant location that is convenient to provide cover from rain or wind.

Expected journey time– this should not be framed as a short journey time being a way of getting away with not intubating a patient. However, journey time and available resources must be considered in risk-benefit assessments, particularly in cases of airway difficulty or anticipated clinical progression. In difficult airway cases, it may be appropriate not to intubate for a short journey to a hospital ED, where there are more airway resources available. Equally, there may be cases where it is appropriate to intubate a stable patient for a long journey where the patient’s condition is anticipated to deteriorate. Mode of transport– in-flight RSI is not currently common practise. It is complex and makes management of complications more difficult.

Unplanned landing once airborne takes time and is impossible at night. It is therefore important to consider the risks and benefits of flying a patient awake versus anaesthetised. No patient should undergo RSI simply to facilitate air transfer. And for some patients, along the road transfer awake may be most appropriate. However, for some patients, for whom the only transport option is air, or where air transport represents the fastest method of achieving a time-critical intervention, and there is a risk of deterioration in flight, early intubation may be appropriate. In summary, we have considered the indications for pre-hospital RSI. We’ve discussed some patient considerations, including that of the elderly, paediatrics, and obese patients, as well as commenting on anticipated difficult airways.

We’ve also considered the decision-making variables that come with logistical problems.