Doppler-derived pulmonary flow reserve detects pulmonary microvascular obstruction in high primates.
BACKGROUND
Despite increasing evidence implicating the pulmonary microcirculation in the pathogenesis of lung conditions such as pulmonary vascular disease, there remain few methods for its evaluation in vivo. We recently demonstrated that the novel index of Doppler-derived pulmonary flow reserve (PFR(dopp)=maximal hyperaemic/basal pulmonary flow) could be reliably measured in high primates. Noting that the microvasculature is the chief regulator of pulmonary blood flow, we hypothesised that PFR(dopp) may detect microcirculatory loss. We therefore studied the relationship between PFR(dopp) and experimentally induced pulmonary microvascular obstruction using microspheres in higher primates.


METHODS
Under ketamine anaesthesia, Doppler sensor-guidewires were placed in the segmental pulmonary artery of three adult baboons. Doppler flow velocity and haemodynamics were recorded at rest and during hyperaemia [as induced by intrapulmonary artery adenosine (200 μg/kg/min)]. Serial PFR(dopp) evaluations were made after cumulative intrapulmonary artery ceramic microspheres administration.


RESULTS
Cumulative microsphere administration progressively reduced PFR(dopp) (1.54 ± 0.26, 1.48 ± 0.20, 1.12 ± 0.04 and 1.18 ± 0.09; baseline, 10(4), 10(5) and 10(6) microspheres boluses; p<0.02) without affecting pulmonary artery pressure, systemic artery pressure or heart rate.


CONCLUSIONS
Doppler-derived PFR can detect partial, progressive pulmonary microvascular obstruction in higher primates. PFR(dopp) may thus have a potential role in the assessment of the pulmonary microcirculation in vivo.
Ilsar
Rahn
R
Cardiology Department, Royal Prince Alfred Hospital, Sydney, Australia.
Chawantanpipat
Chirapan
C
Chan
Kim H
KH
Dobbins
Timothy A
TA
Waugh
Richard
R
Hennessy
Annemarie
A
Celermajer
David S
DS
Ng
Martin K C
MK
D000241:Adenosine / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D003326:Coronary Circulation; D053805:Fractional Flow Reserve, Myocardial; D006439:Hemodynamics; D008168:Lung / Q000098:blood supply* / Q000000981:diagnostic imaging; D008833:Microcirculation; D008863:Microspheres; D010215:Papio; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000473:pathology; D018608:Ultrasonography, Doppler; D014665:Vasodilator Agents / Q000494:pharmacology
D014665:Vasodilator Agents; D000241:Adenosine