Use of dexmedetomidine to facilitate non-invasive ventilation.

Patients with chronic obstructive pulmonary disease and congestive heart failure exacerbations, as well as pneumonia benefit from the use of non-invasive ventilation (NIV), due to increased patient comfort and a reduced incidence of ventilator-associated pneumonia. However, some patients do not tolerate NIV due to anxiety or agitation, and traditionally physicians have withheld sedation from these patients due to concerns of loss of airway protection and respiratory depression. We report our recent experience with a 91-year-old female who received NIV for acute respiratory distress secondary to pneumonia. The duration of NIV was a total time period of 86 h, using the bilevel positive airway pressure mode via a full face mask. The patient was initially agitated with the NIV, but with the addition of the dexmedetomidine, she tolerated it well. The dexmedetomidine was administered without a loading dose, as a continuous infusion ranging from 0.2 to 0.5 mcg/kg/hr, titrated to a Ramsey score of three. This case illustrates the safe use of dexmedetomidine to facilitate NIV, and improve compliance, which may reduce ICU length of stay.

INTRODUCTION

Patients experiencing acute respiratory distress may require either non-invasive ventilation (NIV) or full mechanical ventilation via endotracheal intubation. Although the majority of patients with acute respiratory distress have traditionally been treated with invasive ventilation, select patients are good candidates for NIV. Appropriate indications for NIV in hemodynamically stable patients are hypercapnic respiratory failure due to chronic obstructive pulmonary disease (COPD) exacerbation, congestive heart failure (CHF), obstructive sleep apnea, and pneumonia.[1] Compliance with NIV is often challenging, due to agitation and anxiety associated with the illness as well as the ventilation facemask; such a scenario does not allow the patient to be comfortably and adequately ventilated.[2] Patients must not only be sufficiently sedated to avoid agitation but also alert and cooperative to initiate respiration and protect their airway. However, many doctors report infrequent use of sedation therapy with non-invasive ventilation, as oversedation is associated with respiratory depression and lack of airway protection, leading to invasive mechanical ventilation.[3] An extensive literature search revealed one case series of 10 patients showing that dexmedetomidine is able to provide an appropriate amount of sedation with minimal respiratory depression.[4]

CASE REPORT

A 91-year-old female was admitted to the hospital after a syncopal episode. The patient had a past medical history of COPD, CHF, hypertension, depression, atrial fibrillation, fourth thoracic spine compression fracture, and pneumonia. Surgical and social histories were negative. Furosemide was given once per day at home and in the Intensive Care Unit to treat congestive heart failure, and the patient was given nebulizer treatments of albuterol, ipratropium, levalbuterol, and budesonide throughout her stay in the hospital to treat her COPD.

The patient's admission Glasgow Coma Scale was 13 and her baseline vital signs were heart rate of 101 beats per minute, tachypnea with a respiratory rate of 32 breaths per minute, a blood pressure of 156/65 mm Hg, and an oxygen saturation by pulse oximetry (SpO2) of 91%. Admission blood chemistry showed mild hyponatremia, and an elevated brain natriuretic peptide of 199 ng/L (normal < 99 ng/L). Admission chest radiography taken before bilevel positive airway pressure (BIPAP) showed focal pneumonia in the right lower lung, a widened mediastinum, and enlargement of the cardiac silhouette. Due to respiratory distress, the patient was transitioned from a 50% facemask to BIPAP (settings: FIO2= 50%, 8/4 cm H2O, 14 BPM) and became agitated shortly after. To mitigate her agitation, she was administered dexmedetomidine, without a bolus, at a starting dose of 0.2 μg/kg/hr, and continued on doses ranging from 0.2 to 0.5 μg/kg/hr titrated to a sedation scale. The patient received dexmedetomidine for a total of 40 h. After 1 h the dexmedetomidine was given, the patient was no longer agitated, with a Ramsey Score of three. Her vital signs showed no significant hemodynamic changes 2 h post-dexmedetomidine initiation, while her respiratory rate returned to normal (19 breaths per minute) and SpO2 increased to 97%. The patient did not experience bradycardia or hypotension, which are possible side effects of dexmedetomidine. The echocardiogram while on dexmedetomidine and BIPAP showed an ejection fraction of 60-65%, trace mitral and tricuspid regurgitation, and moderate to severe aortic stenosis. After discontinuation of the dexmedetomidine infusion, and given the previous agitation, haloperidol 1 mg every 6 h intravenously was given for an additional 2 days to maintain the non-agitated state. The total length of non-invasive ventilation was 3 days and 14 h. The patient was neither intubated nor received invasive mechanical ventilation, and was discharged from the hospital and ICU without other respiratory complications.

DISCUSSION

Our recent experience with this patient demonstrates the use of dexmedetomidine to achieve a level of comfort necessary for BIPAP compliance. The use of a sedative, such as a continuously infused benzodiazepine during NIV is contraindicated due to concerns of airway protection and respiratory depression.[2] Dexmedetomidine, however, is a unique sedative that possesses anxiolytic, analgesic, and sympatholytic properties that provide comfort with minimal respiratory depression.[5] Although propofol has been used successfully in conjunction with NIV, its range of effective concentrations is narrower than that of dexmedetomidine, and propofol's concentrations must be tightly monitored by computer-assisted intravenous administration.[6] In comparison to propofol, dexmedetomidine is both easier and safer to use with respect to its range of effective concentrations. Our case study showed that dexmedetomidine aided in achieving a balance between patient sedation and alertness. Attaining this level of consciousness in a patient can allow airway protection, which can reduce morbidity and mortality by avoiding full mechanical ventilation.

With a desirable level of comfort maintained, BIPAP was able to continuously improve the patient's respiratory distress, eventually permitting the patient to be weaned off of BIPAP. The success of NIV prevented further respiratory aggravation that might have required intubation. This allowed the patient to better protect her airway, resulting in a reduced risk of ventilator-associated pneumonia.[7] Furthermore, patients with underlying COPD who receive non-invasive ventilation to treat pneumonia have a lower risk of future intubation, shorter ICU stay, and reduced 2 month mortality.[8]

CONCLUSION

In summation, dexmedetomidine with NIV optimized the efficacy of BIPAP, which reduced the risk of respiratory complications in our patient. The use of continuously infused dexmedetomidine, with its unique sedative properties, makes it ideal in the setting of NIV, and we encourage more widespread use for this indication.