1. Use of High Flow Nasal Cannula and Aerosolized Epoprostenol as a Bridge to Lung Transplantation
Sherwin Morgan, RRT, Steve Mosakowski, RRT, Stephanie Ostrawski, RRT, Leo Leal, RRT, Rich Logan, RN, Edward Garrity, MD
Departments of Respiratory Care Services, Nursing and Pulmonary Medicine, University of Chicago Medicine, Chicago, IL.
Right heart catheterization with Therm-dilution hemodynamic measurements demonstrated right atrial (CVP) pressure – 20 mmHg, RV – pressure; 58/10 mmHg (end diastolic pressure – 18 mmHg), pulmonary artery (PA) pressure – 63/21 mmHg, PA - saturation 46%, CVP saturation – 44%, pulmonary capillary wedge saturation – 99%, cardiac output (CO) – 2.23 L/min and cardiac index – 1.11 L/min/m-2.
The treatment plan consisted of IV Dobutamine 2.5 mcg/kg/min, Phenylephrine (Phenyl) 3.0 mcg/kg/min, Flolan 4ng/kg/min, and AIF.
Four volume based concentrations of AIF were used during treatment period, per protocol; 20,000, 10,000, 5,000, and 2,500 ng/mL. Each dose was prepared as a salt based compound reconstituted in a glycine buffer diluent in a 50 mL IV bag. An Aerogen Solo® (ANEB) nebulizer was connected to the dry side of the MR290.
The bedside nurse was responsible for ordering medications and IV pump operation. Respiratory Care Services (RCS) was responsible for the HFNC and ANEB nebulizer operations.
Starting dose concentration for AIF was 20,000 ng/mL, was infuse into the ANEB at fixed rate of 8 cc/hr. The ANEB control unit was set-up to the continuous mode.
Case report
Epoprostenol (Flolan®, GlaxoSmithKline, NC) is a potent prostaglandin that induces pulmonary artery vasodilation. for the management and treatment of pulmonary arterial hypertension (PAH), right ventricular failure and refractory hypoxemia. It can be administered intravenously (IV) or via aerosolized nebulizer.
Aerosolized inhaled Flolan (AIF) is used for lowering pulmonary vascular resistance (PVR) without effecting systemic circulation, mainly mean arterial blood pressure.
AIF is indicated for the treatment of PAH (MPAP > 30 mmHg) right heart failure (CVP > 16 mmHg and cardiac index < 2.2 L/min/m-2) refractory hypoxemia (PaO2/FiO2 ratio < 150 mm Hg) due to acute lung injury or adult respiratory distress syndrome. Peri-operative use includes; ventricular assist device (LVAD), heart and/or lung transplantation.
A 48 year old male with a history of PAH, class IV, group 3 and previous diagnosis of interstitial lung disease and prior tobacco and inhaled drug use. He had a history of bilateral lobectomies.
An echocardiogram showed evidence of severe right ventricular (RV) dysfunction, dilation, volume overload, and cardiogenic shock. The patient was admitted for syncope and poor pulmonary reserve, with SvO2 of 39%. SvO2 was used as an indication of CO.
He was placed on high flow nasal cannula oxygen therapy (Opti-Flow™ oxygen therapy adult nasal cannula, OPT544) for use with the RT202 adult breathing circuit heated with MR290 auto-feed chamber, Fisher & Paykel Healthcare LTD., Auckland, New Zealand).
The algorithm for starting high flow nasal cannula (HFNC) oxygen gas flow-rates was; Calculated estimated expired minute volume (EEMV) = (VTE)*RR. In this patient, estimated VTE = 450 to 500 mL and RR = 24 breaths/min = 10.8L EEMV. Gas flow rates were set at 3.5 to 4 times the EEMV. In this patient EEMV was 10.8 L x 3.5 = a target gas flow of at least 40 to 50 L/min.
After initiation of HFNC at 0.60 and 40 L/min, the SvO2 improved to 49%.
Discussion
The treatment plan were to increase vaso-activity with the goals of; improving mix venous SvO2 oxygen saturation, allow diuresis with Lasix to improve RV function, and maintain CVP between 7 to 18 mm Hg.
Prior to the start of IV Phenyl, Flolan, and AIF, the SvO2 was 49% and CVP was 20 mm Hg.
After initiation of IV and AIF, the SvO2 improved to > 60%. The CVP was maintained at between 9 and 18 mm Hg.
The SvO2 continued to improved with AIF and diuresis, from 66 to 74%.
Figure 1: Opti-Flow HFNC configured to deliver AIF via IV pump with ANB connected to the dry side of MR290
He was maintained on HFNC, IV Flolan, and AIF for three weeks before receiving bilateral sequential lung transplantation.
In conclusion, RCS was an essential team member for the safe administration of HFNC and AIF during the peri-operative period. There were no reports of adverse events. More clinical investigation is needed to determine the best treatment strategy for the combination of HFNC and AIF as a support bridge for patients that are in need of lung transplantation.