S03: ABORTED EXTRACORPOREAL MEMBRANE OXYGENATION IN LIEU OF KETAMINE INFUSION IN PATIENT WITH STATUS ASTHMATICUS
Kalina Nedeff, MD; Jessica Reyes, MD; Kendall Regional Medical Center
Introduction/Background: 45 year-old male with history of asthma presented with complaints of increasing work of breathing. Patient was in visible distress with audible wheezing noted. Chest x-ray revealed bilateral hyperinflation. Patient was treated with inhaled bronchodilators, intravenous corticosteroids and epinephrine with little improvement. Patient was admitted and placed on scheduled inhaled bronchodilators with corticosteroids, as well as systemic corticosteroids and epinephrine drip. He was placed on a nasal cannula with escalation to non-rebreather. On the second day of admission, the patient stated he had worsening difficulty breathing and requested a ventilator. Serial arterial blood gases with worsening hypercapnic respiratory acidosis led to the decision to secure the airway with endotracheal intubation and mechanical ventilation, and transfer to the intensive care unit.
Methods: Despite maximal medical management, patient failed therapy. The decision was made to undergo emergent veno-venous extracorporeal membrane oxygenation (ECMO). Patient was brought to the operating room and general anesthesia induced via sevoflurane. Patient was also started on ketamine drip. Initial arterial blood gas showed a marked improvement. Decision was made to turn off the sevoflurane and run another sample several minutes later. The second sample was run and showed yet more improvement. Decision was made to abort ECMO attempt, and return patient to his room in the intensive care unit with ongoing ketamine drip added.
Results: Patient continued to improve. The ventilator was weaned, and the patient successfully extubated several days later, with subsequent discharge home.
Discussion/Conclusion: Asthma exacerbations are a frequent cause of morbidity and mortality. Most patients respond promptly to conventional therapies, while others experience status asthmaticus -- worsening respiratory distress requiring invasive ventilation. The risk of barotrauma may be reduced by limiting peak inspiratory pressures while adjusting ventilation to ensure adequate oxygenation, although some hypercarbia with controlled hypoventilation or permissive hypercarbia may be required. CO2 removal and respiratory support may be insufficient and lead to worsening dynamic hyperinflation with increased intrathoracic pressures. In such situations, ECMO has been used in attempts to minimize ventilator-induced lung injury and allow time for lung inflammatory processes to subside. It allows lungs to rest, providing time for bronchiolar relaxation and aggressive pulmonary toilet. Venovenous ECMO offers the advantages of preserved pulmonary blood flow and improved oxygenation of the myocardium.
Several anesthetics have been known to be bronchodilators and have been implemented for treatment of asthma exacerbations refractory to conventional therapies. These anesthetics include, but are not limited to, inhaled volatile anesthetics and ketamine. Both classes have been used on a continuous basis with favorable outcomes. Ketamine is an intravenous anesthetic with sedative, analgesic, and bronchodilator properties. Low dose continuous infusions are often used for postoperative analgesia, but it is not often used in intensive care. Ketamine causes decreased airway resistance and increased pulmonary compliance. The respiratory response to CO2 is maintained and significant respiratory depression spared unless a rapid bolus injection is given.