Non-Invasive Ventilation in the interhospital setting

NIV

The use of interhospital Non-invasive Ventilation (NIV) is controversial

Successful use of NIV requires the clinician to make a careful balance of the benefits of the therapy versus the risk of deterioration and need for intubation.

This is especially important when undertaking interhospital retrieval as a clinical deterioration during transport in a confined space is less than ideal.

NIV

With thanks to Dr Brian Burns (@hawkmoonHEMS) we have just published a study in the Emergency Medicine Journal:

The Open Access Link:

Click Here

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Study Background

  • Non-invasive ventilation (NIV) is an established evidence-based therapy in the management of acute respiratory failure in the ‘hospital’ setting.
  • There is an emerging evidence base for the use of NIV in the urban prehospital setting.
  • There is minimal reporting of the use of NIV in critically unwell patients requiring interhospital transfer.

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Study Overview

“An observational study of patients receiving NIV during interhospital retrieval at an Australian Helicopter Emergency Medical Service (GSA-HEMS) over a 14-month period.”

Results Summary

  • 106 cases (3.51% of reported retrieval missions) involved the use of NIV therapy
  • The most common indication for NIV was pneumonia (34.0%)
  • 86/106 patients received a successful trial of NIV therapy prior to transfer
  • 20/106 patients required intubation prior to the transport after they failed a trial of NIV therapy
  • 58/106 patients were transferred sucessfully on NIV
  • 28/106 patients had their NIV removed for transport
    • None of these 86 patients required intubation or died
  • 17/86 patient required intubation within 24 hours at the receiving centre.
  • NIV was successfully used in all available transport platforms including rotary wing
  • Patients receiving NIV were found to have prolonged mission durations

Clinical Pearls

From the study and wider anecdotal experience there appears to be four major factors to consider when using interhospital NIV:

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  • Patient factors

Patient factors such as co-morbidities, mask fit, air travel anxiety and motion sickness should all be considered. 

Successful NIV use is dependent on a trial of tolerability and patient cooperation. Careful patient selection is essential in order to avoid adverse outcomes. 

Selection for NIV use should be based on local protocols and senior advice.

  • Equipment factors

Not all transport ventilators provide adequate and effective NIV.

The patient may have to work harder to trigger an assisted breath than with devices designed to provide NIV as their primary function.

The oxylog 3000+ appears to provide reasonably effective NIV

  • Oxygen consumption

Oxygen flow can be in the range of 9–35 L/min with the Oxylog 3000+. Operation time can be estimated using a calculation:

Operation Time = Medical gas supply (L) / MV+0.5 (L/min)

Mask air leak can cause increased flow and therefore decreased operation time.

A recent small case series of NIV transport showed a mean oxygen consumption of 232.2 L.

  • Aviation considerations

Aviation factors such as transport distance, vehicle space, weight restrictions and patient access should always be considered.

In this study, six patients were transported by rotary wing with ongoing NIV without complication.

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Conclusions

  • NIV appears to be a safe management option in a select number of patients requiring interhospital transfer.
  • None of the patients transported using NIV required intubation during transport or died during the retrieval.
  • This was a “sick” cohort of patients with seventeen patients requiring intubation and mechanical ventilation at the receiving hospital within 24 hours.
  • Judicious patient selection and senior physician supervision are important contributors to patient safety when using NIV for interhospital transfer.