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Comparison of Acute Hemodynamic Effects of Inhaled Nitric Oxide (iNo) and Inhaled Epoprostenol (iEPO) in Patients with Pulmonary Arterial Hypertension (PAH)

A. M. Shah

Ioana Preston


S. Rafeq

K. E. Roberts

W. Howard

Nicholas Hill


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Conference: 2010 International PHA Conference and Scientific Sessions

Release Date: 06.24.2010

Presentation Type: Abstracts

Shah AM1, Preston IR1, Rafeq S2, Roberts K1, Howard W1, Hill NS1.
1. TUFTS Medical Center, Boston, MA, USA
2. Beth Israel Deaconess Hospital, Boston, MA, USA

BACKGROUND: Inhaled Nitric Oxide (iNO) is routinely used to test for acute vasoreactivity and treat acute right heart syndrome. However, it is expensive, and rebound pulmonary hypertension can happen when discontinued. Inhaled epoprostenol (iEPO) also can lower pulmonary vascular resistance (PVR) with probably less rebound pulmonary hypertension. We initiated a pilot study to compare acute hemodynamic effects of iNO and iEPO, alone and in combination, in patients with PAH. 

METHODS: Patients who underwent elective right heart catherizations (RHCs) [mean PA pressure (mPAP) ≥ 25 mm Hg, PA wedge pressure ≤ 20 mmHg] with acute vasodilator responses to iNO (20ppm) alone, iEPO (50ng/kg/min) alone and the combination were assessed prospectively in a double-blind, randomized fashion. Hemodynamics were measured at baseline, after 10 minutes' administration of each vasodilator and after a 20 minute washout period between each vasodilator agent. 

RESULTS: Thirty patients (F: M=21:9), with a mean age of 63 years underwent RHC as described above. We excluded 4 patients with normal hemodynamics and 5 patients with elevated PAWP (>20 mmHg). WHO Classification of enrolled patients was: Group I = 9, Group II = 9, and 1 each in Groups III, IV and V. Only 1 patient had a positive acute vasodilator response, as defined by current guidelines. Table 1 shows mPAP and change in PVR responses to vasodilators. 

Changes in PVR in response to iNO Vs iEPO had a significant positive correlation (r2 = 0.65) in Group I (Figure 1) and in Group II (r2 = 0.65). Changes in mPAP in response to iNO and iEPO had no significant correlation. The combination of iNO and iEPO did not have an additive effect over each agent alone.

CONCLUSIONIn this small cohort of PH patients, in which most did not have significant acute vasoreactivity, acute vasodilator challenge with iNO and iEPO produced similar vasodilator responses with respect to PVR, while the combination did not have additive effects.

Figure 1:

 Comparison of Acute Hemodynamic Effects of Inhaled Nitric Oxide (iNo) and Inhaled Epoprostenol (iEPO

Table 2: mPAP and PVR in different Groups of PAH.

 

 

Baseline

Δ iNO

Δ iEPO

Δ iNO + iEPO

Group I (n=9)

mPAP

47 ± 12

- 6 ± 2.6

- 5.6 ± 4

- 5.5 ± 4

 

PVR

653 ± 367

- 156 ± 199

- 134 ± 206

- 170 ± 180

Group II (n=9)

mPAP

36 ± 8.5

- 2 ± 3

- 2 ± 3

- 3 ± 3

 

PVR

435 ± 307

- 109 ± 159

- 68 +117

- 117 +122

Group III (n=1)

mPAP

27

- 2

- 3

- 2

 

PVR

385

- 32

- 71

0

Group IV (n=1)

mPAP

45

- 8

- 8

- 9

 

PVR

324

- 103

- 71

- 161

Group V (n=1)

mPAP

49

- 8

- 13

- 14

 

PVR

791

- 67

- 338

- 455