High Velocity Nasal Insufflation (HVNI) with Heliox Improves Management of Tracheal Laceration

Kevin Ives, RRT NPS
UH Rainbow Babies & Children’s Hospital Cleveland, OH

Although individual results may vary, Vapotherm believes the case study is an example of the clinical benefit Vapotherm’s Hi-VNI® Technology can have in a critical care hospital setting.

Patient History and Presentation
A previously healthy 10 year old male was admitted to the Pediatric ICU for post-operative management of a gunshot wound. A singular bullet entered through the patient’s right mandible, transfixed his larynx causing a tracheal laceration and exited through the left anterior chest. After emergency decompression of left tension pneumothorax, surgical intervention was required for flap closure repair at the level of the second and third tracheal rings.

The patient remained intubated and on mechanical ventilation for ten days post-operatively to allow for healing of the tracheal wound. After careful evaluation of the upper airway via laryngoscopy, and positive predictors of lung mechanics and extubation readiness, intravenous dexamethasone was administered to the patient the morning prior to extubation. It was anticipated that the patient would require additional respiratory support after extubation due to the prolonged intubation and a history of tracheal injury.

Treatment and Response
The patient was extubated to High Velocity Nasal Insufflation (HVNI), (Precision Flow, Vapotherm, Exeter, NH) adult cannula at 12 L/min with a FiO2 of 40%. One hour post-extubation, the patient’s dyspnea worsened and he developed marked stridor, so 70/30 Heliox (Precision Flow Heliox Vapotherm, Exeter, NH) was initiated at the same flow rate (12 L/min). Racemic Epinephrine aerosols were given via Aeroneb vibrating mesh nebulizer (Aerogen, Galway IR) through the Aeroneb Aerosol Adapter (Vapotherm Exeter, NH) placed in-line with the HVNI circuit. Over the course of the next eight hours (fig. 1) the patient’s Heliox flow was increased to 20 L/min and gas admixture was subsequently changed to 75/25. Upon initiation of Heliox, a reduction in stridor was noted, SpO2   normalized, work of breathing improved, and the need for aerosolized racemic epinephrine decreased. The patient’s respiratory rate remained at <24 breaths/min through the duration of early morning hours while heart rate normalized. There was a noticeable reduction in inspiratory stridor and diaphoresis. Following an 8-hour period of optimal Heliox HVNI the patient was transitioned to HVNI with air oxygen. The flow rate was subsequently weaned per physician guidance.

 
Effect of Flow and HeOx on Respiratory Rate (over time – 24hr)
 
Effect of Flow, Heliox, and Aerosolized Medication on Respiratory Rate

Fig 1. Effect of Flow, Heliox, and Aerosolized Medication on Respiratory Rate over time (shown as 24HR).  Bars indicate respiratory rate, and solid line corresponding flow rate. Heliox administration indicated by Grey shading. Aerosolized administration of racemic epinephrine indicated by the red arrows.

 

Interpretation
Heliox provides a vehicle for optimizing gas transport by decreasing resistance to airflow by improving laminar flow and reducing work of breathing. The chemical properties of Helium (lower density than air) are particularly beneficial in the face of high airway resistance. Delivering gas through a high resistance pathway such as the compromised upper airway can be challenging. Heliox used in conjunction with HVNI has been shown to improve ventilation and oxygenation and played an integral role in in the successful extubation of this pediatric patient with a life-threatening tracheal injury. Once the optimal flow and gas admixture were achieved, the patient began to show clinical benefit by a reduction in signs and symptoms of extrathoracic airway obstruction, including progressive resolution of stridor, improved dyspnea and reduced work of breathing. While benefits from Heliox through HVNI were realized, an attempt to optimize aerosol delivery was also made. Perry demonstrated that aerosolized medication delivery through a high flow nasal cannula, is a function of cannula size, and flow rate.1 Although clinical benefit of aerosolized drug delivery is considered comparable using Heliox or oxygen, the use of a larger diameter cannula (adult) promoted ideal conditions for drug delivery in these conditions. The patient proceeded toward discharge from the pediatric intensive care unit shortly thereafter.

Conclusion
The use of Heliox HVNI in conjunction with optimizing flow rate demonstrated encouraging results as it played a role in facilitating successful extubation of a pediatric patient with severe traumatic extrathoracic airway obstruction and laryngeal edema post extubation. Flow rates and the appropriate gas mixture need to be selected with precision.  Patient-specific treatment goals were established and HVNI Heliox, and aerosolized medications were used together to provide careful management strategy that achieved positive results.

References

1. Perry Sa, Kesser KC, Geller DE, Selhorst DM, Rendle JK, Hertzog JH,. Influences of cannula size and flowrate in aerosol delivery through the vapotherm Humidified High Flow nasal cannula system.
2019-02-07T14:27:36-04:00Feb 7|Patient Case Studies|