Pulmonary blood flow distribution during partial liquid ventilation

Abstract

Regional pulmonary blood flow was investigated with radiolabeled microspheres in four supine lambs during the transition from conventional mechanical ventilation (CMV) to partial liquid ventilation (PLV) and with incremental dosing of perfluorocarbon liquid to a cumulative dose of 30 ml/kg. Four lambs supported with CMV served as controls. Formalin-fixed, air-dried lungs were sectioned according to a grid; activity was quantitated with a multichannel scintillation counter, corrected for weight, and normalized to mean flow. During CMV, flow in apical and hilar regions favored dependent lung (P < 0.001), with no gradient across transverse planes from apex to diaphragm. During PLV the gradient within transverse planes found during CMV reversed, most notably in the hilar region, favoring nondependent lung (P = 0.03). Also during PLV, flow was profoundly reduced near the diaphragm (P < 0.001), and across transverse planes from apex to diaphragm a dose-augmented flow gradient developed favoring apical lung (P < 0.01). We conclude that regional flow patterns during PLV partially reverse those noted during CMV and vary dramatically within the lung from apex to diaphragm.

High-frequency oscillatory ventilation: What large-animal studies have taught us!

“…The perfluorocarbon reverses the atelectasis in the dependent lung and directs pulmonary blood flow to the non-dependent lung (40). Because of its lower V T and peak alveolar pressure, HFO could ventilate the nondependent lung with adequate mean airway pressure to avoid overdistension and atelectasis in this region (41). Arnold (37) proposed that the small V T associated with HFO minimizes the shear stress and subsequent injury in the regions containing liquid and air.…”

Feasibility of lung cancer hyperthermia using breathable perfluorochemical (PFC) liquids. Part I: Convective hyperthermia

“…These advantages are associated with restoration of alveolar ventilation, shifts in pulmonary blood flow to the non-dependent regions (thought to be caused by PFC density; table 1), with inhibition of hypoxic pulmonary vasoconstriction in mid-to-lower regions, reducing the vertical perfusion gradient in comparison with gas ventilation for TLV 36 and PLV 35,37 .…”

Erhaltene spontane Atemt�tigkeit w�hrend partieller Fl�ssigkeitsbeatmung

“…Daraus resultiert eine Reduktion von Ventilations-Perfusions-Verteilungsstö-rungen mit konsekutiver Besserung des Gasaustausches [11].…”

“…Eine erhaltene Spontanatmung kann das VentilationsPerfusions-Verhältnis und die Oxygenierung durch bevorzugte Ventilation abhän-giger Lungenpartien günstig beeinflussen, während maschinelle Beatmung zu einer bevorzugten Ventilation nichtabhängiger Partien führt [16]. Da PLV bei lungenkranken Tieren bereits durch Rekrutierung von Alveolen und durch Umverteilung der Perfusion von abhängigen in nichtabhängige, meist besser belüftete Lungenpartien bereits das VentilationsPerfusions-Verhältnis und die Oxygenierung verbessern kann [11],ist es denkbar, dass eine erhaltene spontane Atemtätig-keit keinen zusätzlichen positiven Einfluss mehr auf die Oxygenierung hat. Die erhaltene, mit PAV unterstützte Spontanatmung führte bei unseren Versuchstieren mit Lungenerkrankung jedoch zu einer Verbesserung der Oxygenierung und tendenziell zu einem niedrigeren Shunt und unterstreicht damit die Bedeutung der erhaltenen spontanen Eigenatmung auch unter PLV für den Gasaustausch.…”