2005 OPEN FORUM Abstracts
Adult Status Asthmaticus Requiring ECMO
Nicholas Widder, RRT-NPS; Joseph Hylton, RRT-NPS; Thomas Stern, MD; William Miles, MD, FACS, FCCM; Christine Schroeder, BS, RRT
A 19 Year old African American male, with significant history of asthma, presents in the ED in Status Asthmaticus after three to four days of "cold-like" symptoms. Home medications include albuterol, Advair, and Singulair. Patient has at least one documented intubation for asthma four years prior to admission, requiring five weeks of mechanical ventilation and admission to a rehabilitation facility for reconditioning. Family history includes paternal death from asthma when in early 20's.
Initial blood gas analysis reveled pH 7.21/69/75 on 6 l/min. After continuous albuterol nebulizer therapy, IV steroids and magnesium, and initiation of BiPAP, blood gases of 7.29/49/90 were obtained.
The patient was transferred to ICU, where he was electively intubated for worsening respiratory status, and placed on mechanical ventilation. Conventional methods of mechanical ventilation, including low rate, low volume, long expiratory phase, and apneic periods with forced exhalation were unsuccessful (PaCO2 > 180), and the patient was placed on PCV via an anesthesia ventilator, and started on inhaled anesthetic gas (isoflurane) in an effort to bronchodilate the patient. Patient was also receiving nebulized heparin, and albuterol MDI. Blood gases initially improved; however, ventilation was complicated by mucous plugging and ARDS.
Patient remained on isoflurane for the next 8 days, failing three attempts to convert to conventional ventilation, even with the use of heliox, and continuous infusion of IV terbutaline.
On day nine, the patient was cannulated and placed on veno-venous ECMO, with continuous hemofiltration. Isoflurane was removed on implementation of ECMO, and the patient was placed on conventional mechanical ventilation. Lung mechanics were noted to rapidly improve, with a significant reduction in air trapping and airway resistance within 8 hours.
On day four of ECMO, the sweep gas was removed for 12 hours, and the patient was de-cannulated on day five.
Patient remained on the ventilator due to critical illness neuropathy, and had a tracheotomy performed on day 17.
- This is an interesting case due to the failure of conventional ventilation strategies. The patient was treated aggressively in the ED, including use of continuous albuterol, IV magnesium and steroids, and NIMV. Ipratropium was not used because of a reported non-specific "reaction" to the drug in the past.
- Heparin nebulization was attempted in an effort to deactivate histamine. There was some concern as to how well the nebulizer delivered medications in a closed anesthesia circle, but this was not addressed.
- Veno-venous ECMO is a technique where blood is drained from a large vein, put through a membrane, where oxygen is added and CO2 is removed, and then fed back into the patient's right atrium. This differs from veno-arterial ECMO, where the post membrane blood is infused into the aorta.
- While not always used with ECMO, continuous hemofiltration was added to the circuit in an effort to reduce circulating cytokines, which may have added to the rapid improvement of lung mechanics upon initiation of ECMO. This raises the question that perhaps the institution of plasmapherisis may have provided benefit to the patient if instituted early in the course of treatment.
- Critical illness neuropathy can cause profound weakness, which will prolong mechanical ventilation. Several factors added to the risk of development of this syndrome, including the use of high dose steroids, the use of a steroid based neuromuscular blocker (vecuronium) for seven days and prolonged exposure to isoflurane. Perhaps earlier use of atricurim or cis-atricurium may have been of benefit.
The patient has since been transferred to a step down unit, removed from mechanical ventilation, and is awaiting tracheal decannulation.