Measurement of bronchial blood flow with radioactive microspheres in awake sheep

Abstract

Distribution of bronchial blood flow was measured in unanesthetized sheep by the use of two modifications of the microsphere reference sample technique that correct for peripheral shunting of microspheres: 1) A double microsphere method in which simultaneous left and right atrial injections of 15-microns microspheres tagged with different isotopes allowed measurement of both pulmonary blood flow and shunt-corrected bronchial blood flow, and 2) a pulmonary arterial occlusion method in which left atrial injection and transient occlusion of the left pulmonary artery prevented delivery to the lung of microspheres shunted through the peripheral circulation and allowed systemic blood flow to the left lung to be measured. Both methods can be performed in unanesthetized sheep. The pulmonary arterial occlusion method is less costly and requires fewer calculations. The double microsphere method requires less surgical preparation and allows measurement without perturbation of pulmonary hemodynamics. There was no statistically significant difference between bronchial blood flow measured with the two methods. However, total bronchial blood flow measured during pulmonary arterial occlusion (1.52 +/- 0.98% of cardiac output, n = 9) was slightly higher than that measured with the double microsphere method (1.39 +/- 0.88% of cardiac output, n = 9). In another series of experiments in which sequential measurements of bronchial blood flow were made, there was a significant increase of 15% in left lung bronchial blood flow during the first minute of occlusion of the left pulmonary artery. Thus pulmonary arterial occlusion should be performed 5 s after microsphere injection as originally described by Baile et al. (1).(ABSTRACT TRUNCATED AT 250 WORDS)

Sclerosis therapy of bronchial artery attenuates acute lung injury induced by burn and smoke inhalation injury in ovine model

“…To substantiate the changes in bronchial blood flow, measurements were taken using the fluorescent microsphere technique (Interactive Medical Technologies, West Los Angeles, CA) that we had previously developed [23]. At 0 h, Before Injection (BI), After Injection (AI), 6 h, and 24 h, ~12 × 10 6 fluorescent colored microspheres (15.0 ± 0.1 µm) were injected into the left atrium.…”

“…At 0 h, Before Injection (BI), After Injection (AI), 6 h, and 24 h, ~12 × 10 6 fluorescent colored microspheres (15.0 ± 0.1 µm) were injected into the left atrium. Since some of the microspheres may pass through some of the larger vessels in the non-bronchial pulmonary circulation, the pneumatic occluder on the left pulmonary artery was inflated immediately after microsphere injection to prevent any pulmonary artifact to affect the bronchial blood flow measurement [23]. To calibrate microsphere numbers per blood flow, blood was withdrawn from the aorta with a Harvard pump (Harvard Apparatus model 55–1143, South Natick, MA) at a rate of 10 mL/min; the withdrawal was started before microsphere injection and continued for 2 min.…”

A novel bronchial artery catheterization technique with preserved blood flow in an ovine model

“…Microspheres were also injected at baseline (BL) and 6 h after burn and smoke inhalation injury in all groups. Our technique for using microspheres to measure bronchial blood flow has previously been described [2,22] …”

“…Total blood flow represents only ∼1% to 3% of cardiac output in bronchial circulation under normal conditions [1,2]. However, during certain situations such as smoke inhalation, the airway blood flow may increase more than 10-fold, yielding blood flows near 10% of the cardiac output [3].…”

Intracardiac Echocardiography Guided Transeptal Catheter Injection of Microspheres for Assessment of Cerebral Microcirculation in Experimental Models

“…Since then, several studies have introduced modifications to the methods including the description of the reference sample for the calculation of blood flow [2], the injection of microspheres into the left atrium (LA) to minimise peripheral and central shunting [3], transient occlusion of the pulmonary artery also to minimise shunting [4], and the use of two different radioactive spheres and simultaneous LA and right atrium (RA) injections ( via a left thoracotomy ) to discriminate shunting from pulmonary blood flow [5]. Substantial modifications in this technique also included the use of nonradioactive spheres [6] which added significant environmental and logistical advantages.…”