Tracheobronchial blood flow after a modified canine lung autotransplant: effect of omental wrapping.
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Animals↗
Biomedical subjects
E M Baile
Publications and source records attributed to E M Baile.
Effects of inspiratory resistance, inhaled beta-agonists and histamine on canine tracheal blood flow.
Tracheobronchial blood flow is potentially important in asthma as it could either influence the clearance of mediators from the airways, thus affecting the duration and severity of bronchospasm, or enhance oedema formation with a resultant increase in airflow obstruction. In anaesthetized dogs, spontaneously breathing via a tracheostomy, we investigated the effects of three interventions which are relevant to acute asthma attacks and could potentially influence blood flow and its distribution to the mucosa and remaining tissues of the trachea: 1) increased negative intrathoracic pressure swings (-25 +/- 1 cmH2O) induced by an inspiratory resistance; 2) variable inhaled doses of a beta-adrenoceptor-agonist (terbutaline); and 3) aerosolized histamine sufficient to produce a threefold increase in pulmonary resistance. Microspheres labelled with different radioisotopes were used to measure blood flow. Resistive breathing did not influence tracheobronchial blood flow. Following a large dose of terbutaline, mucosal blood flow (Qmb) increased by 50%. After inhaled histamine, Qmb reached 265% of the baseline value. We conclude that, whereas increased negative pressure swings do not influence tracheobronchial blood flow or its distribution, inhalation of aerosolized terbutaline, corresponding to a conventionally nebulized dose, increases mucosal blood flow. Our results also confirm that inhaled histamine, in a dose sufficient to produce moderate bronchoconstriction, increases tracheal mucosal blood flow in the area of deposition.
Administration, Inhalation↗
A comparison of laser Doppler flowmetry with the radiolabelled microsphere reference flow technique to measure tracheal blood flow in dogs.
Measurements of tracheal wall blood flow were made in anaesthetized, ventilated dogs during resting ventilatory conditions, during application of positive end-expiratory pressure (PEEP) and during eucapnic hyperventilation of dry air, using laser Doppler flowmetry and the radiolabelled microsphere reference flow technique. Six regions of the trachea were studied in each dog, and the average laser Doppler flowmetry measurement derived from 12 sites within each region was compared with the reference flow measurement, obtained using 15 microns diameter microspheres labelled with 113Sn, 103Ru, 141Ce or 151Gd. Under each set of ventilatory conditions, there was a weak, but significant, correlation between laser Doppler flowmetry and reference flow values (baseline r = 0.44, hyperventilation r = 0.44, and PEEP r = 0.74). Average laser-Doppler flowmetry and reference flow values showed a similar reduction from baseline during application of PEEP. The mean (SD) change from baseline, expressed as a percentage, was -63 (15)% for laser-Doppler flowmetry values, and -63 (21)% for reference flow values. However, there was no correlation between the magnitude of change measured in individual regions using the two techniques. During hyperventilation, laser Doppler flowmetry measurements showed variable changes from baseline, and the mean change was -12 (45)%, which was not significantly different from zero. Reference flow values increased during hyperventilation, the mean change being 87 (77)%. The results indicate that laser Doppler flowmetry and reference flow measurements of airway wall blood flow are not directly comparable.
Animals↗
Measurement of airway wall blood flow in sheep by laser-Doppler flowmetry: interpretation and problems.
We have used laser-Doppler flowmetry (LDF), a technique that detects movement of erythrocytes, to measure tracheal and bronchial wall blood flow in anesthetized open-chest sheep. LDF derives continuous measurements noninvasively, although fiber-optic bronchoscopy is necessary to introduce the LDF probe into the airways. The response of the LDF flow signals at four regions of the airway walls to varying bronchial arterial flow rates was examined in both live and dead sheep by cannulation and subsequent perfusion of the common bronchial artery at different flow rates by use of a roller pump. In the live sheep, variations in bronchial arterial blood flow resulted in variations in LDF signals in the principal bronchus and in lobar and segmental bronchi but not in the trachea. In the dead sheep, variations in bronchial arterial blood flow resulted in variations in LDF signals in all four regions. Within regions, the average response of the LDF signals to varying bronchial blood flow rates was approximately linear in both live and dead sheep, but considerable site-to-site variation in response was observed. In the live sheep, significant LDF signals were observed when the bronchial arterial flow was set to zero and when the bronchial artery was perfused with dextran solution, which would in theory be expected to produce no LDF signal. A small LDF signal was also detected under zero flow conditions in the dead sheep. These observations suggest that the LDF technique, in addition to detecting blood flow from the bronchial artery also detects background noise and/or collateral circulation.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
A method for estimating the Young's modulus of complete tracheal cartilage rings.
Cartilage is primarily responsible for maintaining the stability of the large airways; yet very little is known about the mechanical properties of airway cartilage. This work establishes a technique whereby average values for the equilibrium modulus of excised tracheal cartilage rings can be obtained. An apparatus was designed to apply preset deformations to a tracheal segment and to monitor the deforming force. Segments of four human tracheae obtained postmortem and containing three rings were mounted in the apparatus after being stripped of posterior membrane. The load-deformation behavior was analyzed with a model on the basis of thin curved beam theory. Agreement between predicted deformed shapes and those observed was good in three of the four cases and in the case of a short length of longitudinally split rubber tube. The technique is suitable for comparing mechanical properties of cartilage before and after an intervention.
Biomechanical Phenomena↗
Direct injury to the bronchial vasculature in anesthetized sheep.
Injury to the bronchial vasculature may contribute to liquid and solute leakage into the lung during noncardiac pulmonary edema. The purpose of this study was to measure changes in hemodynamics, pulmonary mechanics, extravascular lung water, and lung morphometry after selectively injuring the bronchial vasculature in anesthetized sheep. In two groups of seven sheep, we injected oleic acid (0.1 ml/kg) or normal saline directly into the bronchoesophageal artery. We measured systemic and pulmonary arterial pressures, cardiac output, oxygen saturation, pulmonary resistance and compliance, and lung volumes before and 1 and 4 h after injection. The lungs were removed for measurement of extravascular water, histology, and morphometry. Four hours after injection of oleic acid, cardiac output decreased but pulmonary arterial pressure did not change. In addition, pulmonary resistance increased and dynamic compliance and vital capacity decreased. Extravascular lung water was slightly but significantly greater in the oleic acid group. Histological examination showed interstitial edema and leukocytes in airway walls and sloughing of bronchial epithelium but little or no alveolar edema. Morphometric analysis showed significant thickening of airway walls. We conclude that direct injury to the bronchial vasculature increases lung resistance, decreases dynamic compliance, and increases extravascular lung water by the accumulation of an inflammatory infiltrate in airway walls.
Airway Resistance↗
Mechanism for increase in tracheobronchial blood flow induced by hyperventilation of dry air in dogs.
To test whether the consistent increase in tracheal and bronchial blood flow observed in dogs during hyperventilation of dry air might be the result of release of mediators such as vasodilatory prostaglandins or neuropeptides, we studied two groups of anesthetized mechanically ventilated dogs. Group 1 (n = 6) was hyperventilated for four 30-min periods with 1) warm humid air (38-40 degrees C, 100% relative humidity), 2) warm dry air (38-40 degrees C, 0% relative humidity), 3) warm humid air, and 4) warm dry air. After period 2, a loading dose of indomethacin (4 mg/kg iv) was given over 15 min followed by a constant infusion (4 mg.kg-1.h-1). Group 2 (n = 10) was hyperventilated for four 15- to 20-min periods by use of the protocol described above. After period 3 (group 2a) or period 2 (group 2b), topical 4% lidocaine hydrochloride solution was instilled into the trachea and main stem bronchi. Five minutes before the end of each period of hyperventilation, cardiac output and vascular pressures were measured. To determine airway blood flow, differently labeled radioactive microspheres were injected into the left atrium. After the last measurements, dogs were killed and the lungs excised. Blood flow to the trachea, main stem bronchi, and parenchyma (group 1 only) was calculated. Results showed that hyperventilation of dry air produced a significant increase in blood flow to the trachea and bronchi (period 2). In group 1, this increase was attenuated (P less than 0.02) after administration of indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Airway blood flow response to eucapnic dry air hyperventilation in sheep.
Eucapnic hyperventilation, breathing dry air, produces a two- to fivefold increase in airway blood flow in the dog. To determine whether airway blood flow responds similarly in the sheep we studied 16 anesthetized sheep. Seven sheep (1-7) were subjected to two 30-min periods of eucapnic hyperventilation breathing 1) warm humid air [100% relative humidity (rh)] followed by 2) warm dry air [0% rh] at 40 breaths/min. To determine whether there was a dose-response effect on blood flow of increasing levels of hyperventilation of dry air, another nine sheep (8-16) were subjected to four 30-min periods of eucapnic hyperventilation breathing warm humid O2 followed by warm dry O2 at 20 or 40 breaths/min in random sequence. Five minutes before the end of each period of hyperventilation, hemodynamics, blood gases, and tracheal mucosal temperature were measured, and tracheal and bronchial blood flows were determined by injection of 15- or 50-micron-diam radiolabeled microspheres. After the last measurements had been made, all sheep were killed, and the lungs and trachea were removed for determination of blood flow to trachea, bronchi, and parenchyma. In sheep 1-7, warm dry air hyperventilation at 40 breaths/min produced an increase in blood flow to trachea (7.6 +/- 3.5 to 17.0 +/- 6.2 ml/min, P less than 0.05) and bronchi (9.0 +/- 5.4 to 18.2 +/- 8.2 ml/min, P less than 0.05) but not to the parenchyma. When blood flow was compared with the two ventilatory rates (sheep 8-16), tracheal blood flow increased (9.1 +/- 3.3 to 18.2 +/- 6.1 ml/min, P less than 0.05) at a rate of 40 breaths/min but not at 20 breaths/min.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Hypertonic aerosol inhalation does not alter central airway blood flow in dogs.
Tracheobronchial blood flow in dogs increases with cold or dry air hyperventilation, possibly as a result of airway drying leading to increased osmolarity of airway surface fluid. This study was designed to examine whether administration of aerosols of various tonicity to alter airway surface fluid osmolarity would induce similar blood flow changes. Tracheobronchial blood flow was measured by the radioactive microsphere technique in six anesthetized dogs ventilated with warm humid air (100% relative humidity) for 15 min (period 1), air containing ultrasonically nebulized saline aerosol (1,711 mosmol/kg) for 3 min (period 2) and 12 min (period 3), and the same aerosol at a higher nebulizer output for a further 3 min (period 4). Between periods 3 and 4, the dogs were ventilated with warm humid air for 30 min to reestablish base-line conditions. In another five dogs, measurements were made after 30 min of ventilation with 1) warm humid air, 2) isotonic saline aerosol, 3) warm humid air, 4) distilled water aerosol (3 dogs), and hypertonic saline aerosol (2 dogs). After the last measurement was made, each dog was killed, the trachea and major bronchi were excised, and blood flow was calculated. No change in blood flow was found during any period of aerosol inhalation. The osmolar load imposed on the airways was estimated and was similar to that occurring during cold or dry air hyperventilation. These data suggest that increasing osmolarity of airway surface fluid does not explain the blood flow changes seen during hyperventilation of cold or dry air.
Aerosols↗
Phrenic nerve function and its relationship to atelectasis after coronary artery bypass surgery.
Atelectasis following coronary artery bypass surgery (CAB) occurs in the majority of patients. To determine the importance of operative variables in the development of postoperative atelectasis and the incidence of phrenic nerve injury caused by topical cold cardioplegic solution, we studied 57 patients (53 male, four female) undergoing CAB. Their mean age, +/- SD, was 58 +/- 13 years. Transcutaneous stimulation was used to evaluate phrenic nerve function preoperatively and postoperatively in 52 patients. An unequivocal paresis of the phrenic nerve was documented in five patients. In an additional 27 patients, the amplitude of the compound diaphragm action potential was reduced postoperatively. However, methodologic limitations did not allow the conclusion that this was secondary to a phrenic axonal degeneration. Discriminant analysis of intraoperative variables showed more severe atelectasis with a larger number of grafts, with a longer operative and bypass time, when the pleural space was entered, when a right atrial drain and a cardiac insulating pad were not used, and with a lower body temperature. It is concluded that phrenic paresis may occur after CAB and topical cold cardioplegia, but that other factors must explain the atelectasis found in the majority of patients.
Cardioplegic Solutions↗
Effect of autonomic blockade on tracheobronchial blood flow.
Tracheobronchial blood flow increases two to five times in response to cold and warm dry air hyperventilation in anesthetized tracheostomized dogs. In this series of experiments we have attempted to attenuate this increase by blockade of the autonomic nervous system. Four groups of anesthetized, tracheostomized, open-chest dogs were studied. Group 1 (n = 5) were hyperventilated for 30 min with 1) warm humid [approximately 26 degrees C, 100% relative humidity, (rh)] air followed by bilateral vagotomy, 2) warm humid air, 3) cold (-22 degrees C, 0% rh) dry air, and 4) warm humid air. Groups 2, 3, and 4 (n = 3/group) were hyperventilated for 30 min with 1) warm humid (approximately 41 degrees C, 100% rh) air, 2) warm dry (approximately 41 degrees C) air, 3) warm humid air, and 4) warm dry air. Group 2 were controls. Group 3 were given phentolamine, 0.6 mg/kg intravenously, as an alpha-blockade, and group 4 were given propranolol, 1 mg/kg, as a beta-blockade after warm dry air hyperventilation (period 2). Five minutes before the end of each 30-min period of hyperventilation, measurements of vascular pressures, cardiac output, arterial blood gases, and inspired, body, and tracheal temperatures were measured, and differently labeled radioactive microspheres were injected into the left atrium to make separate measurements of airway blood flow. After the last measurements had been made animals were killed and their lungs were excised. Blood flow to the airways and lung parenchyma was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Effect of cold and warm dry air hyperventilation on canine airway blood flow.
Tracheobronchial blood flow increases with cold air hyperventilation in the dog. The present study was designed to determine whether the cooling or the drying of the airway mucosa was the principal stimulus for this response. Six anesthetized dogs (group 1) were subjected to four periods of eucapnic hyperventilation for 30 min with warm humid air [100% relative humidity (rh)], cold dry air (-12 degrees C, 0% rh), warm humid air, and warm dry air (43 degrees C, 0% rh). Five minutes before the end of each period of hyperventilation, tracheal and central airway blood flow was determined using four differently labeled 15-micron diam radioactive microspheres. We studied another three dogs (group 2) in which 15- and 50-micron microspheres were injected simultaneously to determine whether there were any arteriovenous communications in the bronchovasculature greater than 15 micron diam. After the last measurements had been made, all dogs were killed, and the lungs, including the trachea, were excised and blood flow to the trachea, left lung bronchi, and parenchyma was calculated. Warm dry air hyperventilation produced a consistently greater increase in tracheobronchial blood flow (P less than 0.01) than cold dry air hyperventilation, despite the fact that there was a smaller fall (6 degrees C) in tracheal tissue temperature during warm dry air hyperventilation than during cold dry air hyperventilation (11 degrees C), suggesting that drying may be a more important stimulus than cold for increasing airway blood flow. In group 2, the 15-micron microspheres accurately reflected the distribution of airway blood flow but did not always give reliable measurements of parenchymal blood flow.
Animals↗
Tracheobronchial and upper airway blood flow in dogs during thermally induced panting.
Tracheobronchial blood flow increases two- to fivefold in response to isocapnic hyperventilation with warm dry or cold dry air in anesthetized, tracheostomized dogs. To determine whether this response is governed by central nervous system thermoregulatory control or is a local response to the drying and/or cooling of the airway mucosa, we studied eight anesthetized spontaneously breathing dogs in a thermally controlled chamber designed so that inspired air temperature, humidity, and body temperature could be separately regulated. Four dogs breathed through the nose and mouth (group 1), and four breathed through a short tracheostomy tube (group 2). Dogs were studied under the following conditions: 1) a normothermic control period and 2) two periods of hyperthermia in which the dogs panted with either warm 100% humidified air or warm dry (approximately 10% humidified) air. Radiolabeled microspheres (15 +/- 3 micron diam) were injected into the left ventricle as a marker of nasal, lingual, and tracheobronchial blood flow. After the final measurements, the dogs were killed and tissues of interest excised. Results showed that lingual and nasal blood flow (ml.min-1.g-1) increased during panting (P less than 0.01) in both groups and were not affected by the inspired air conditions. In group 1, tracheal mucosal blood flow barely doubled (P less than 0.01) and bronchial blood flow did not change during humid and dry air panting. In group 2, there was a sevenfold increase in tracheal mucosal and about a threefold increase in bronchial blood flow (P less than 0.01), which was only observed during dry air panting.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Cardiac temperature and cardioplegic volume during cardiopulmonary bypass.
This study was designed to compare two methods of cardiac drainage on the rate of change of cardiac temperature and volume of cardioplegic solution required to maintain the cardiac temperature less than or equal to 12 degrees C in patients undergoing coronary artery bypass surgery. Two groups of 10 patients were studied who were comparable in age, sex, and smoking history. In Group 1, cardiac drainage was achieved by using single-port drainage cannulae in the superior and inferior vena cava with caval tapes. Group 2 patients had a caval atrial cannula to drain the noncoronary collateral flow from the right atrium as well as that from the venae cavae. Both groups had a sump line in the left ventricle to drain the bronchopulmonary anastomotic blood flow. Results from the study showed that there was no difference between groups in the initial amount of cold cardioplegic solution required to arrest and cool the heart or the initial recording of ventricular temperatures. However, the volume of cardioplegic solution required to maintain the cardiac temperature at less than or equal to 12 degrees C after administration of the initial volume was less (P less than 0.05) for Group 2 than Group 1. Group 2 also had a slower rate of increase in cardiac temperature than Group 1 (P less than 0.01). Results from this study indicate that the constant removal of blood from both cardiac chambers during coronary artery bypass surgery significantly reduces the rate of myocardial rewarming and decreases the amount of cardioplegic solution required to maintain a given cardiac temperature.
Aged↗
Relationship between regional pulmonary edema and blood flow.
We studied the effect of edema on the regional distribution of pulmonary blood flow in 12 anesthetized dogs. Two were controls, six had low-pressure pulmonary edema, and four had high-pressure pulmonary edema. All were ventilated with 100% O2. The physiological shunt fraction (Qs/QT), as an indicator of the degree of venous admixture, was determined by measuring the arterial and venous blood gases and the hemoglobin at different times during the experiment. Cardiac output (QT) was modestly increased by opening the femoral arteriovenous shunts. The initial regional blood flow (Qi) and final regional blood flow (Qf) were marked before and after the shunts were opened, using two differently labeled macroaggregates. The dogs were then killed, and the lungs were removed and sampled completely so that Qi and Qf and the amount of regional extravascular lung water (Wdl) in each regional sample could be measured (sample size: wet wt = 5.9 +/- 2.9 g, n = 833; Wdl ranged from 5.15 +/- 1.18 to 14.42 +/- 2.34 g). The data show that QS/QT increased as QT increased in the three conditions studied. However, there was no correlation between Wdl and Qi, Qf, or the relative change in regional blood flow. The data also show that gravity affects regional blood flow more than it affects regional edema. We conclude that the increased Qs/QT seen with increased pulmonary blood flow cannot be explained by a preferential increase of blood flow to the more edematous regions.
Animals↗
Role of tracheal and bronchial circulation in respiratory heat exchange.
Due to their anatomic configuration, the vessels supplying the central airways may be ideally suited for regulation of respiratory heat loss. We have measured blood flow to the trachea, bronchi, and lung parenchyma in 10 anesthetized supine open-chest dogs. They were hyperventilated (frequency, 40; tidal volume 30-35 ml/kg) for 30 min or 1) warm humidified air, 2) cold (-20 degrees C dry air, and 3) warm humidified air. End-tidal CO2 was kept constant by adding CO2 to the inspired ventilator line. Five minutes before the end of each period of hyperventilation, measurements of vascular pressures (pulmonary arterial, left atrial, and systemic), cardiac output (CO), arterial blood gases, and inspired, expired, and tracheal gas temperatures were made. Then, using a modification of the reference flow technique, 113Sn-, 153Gd-, and 103Ru-labeled microspheres were injected into the left atrium to make separate measurements of airway blood flow at each intervention. After the last measurements had been made, the dogs were killed and the lungs, including the trachea, were excised. Blood flow to the trachea, bronchi, and lung parenchyma was calculated. Results showed that there was no change in parenchymal blood flow, but there was an increase in tracheal and bronchial blood flow in all dogs (P less than 0.01) from 4.48 +/- 0.69 ml/min (0.22 +/- 0.01% CO) during warm air hyperventilation to 7.06 +/- 0.97 ml/min (0.37 +/- 0.05% CO) during cold air hyperventilation.
Animals↗
Bronchopulmonary anastomotic and noncoronary collateral blood flow in humans during cardiopulmonary bypass.
The sole source of blood returning to the left atrium during cardiopulmonary bypass, while the aorta is cross-clamped, is the bronchopulmonary anastomotic blood flow. In addition, there is noncoronary collateral blood flow which returns to the right atrium. Routinely, the bronchopulmonary anastomotic flow is drained from the left ventricle by a cannula and returned to the main circuitry via a cardiotomy reservoir. The noncoronary collateral flow may be vented similarly by introducing a cannula into the right atrium. Both the anastomotic and the noncoronary collateral flow can be measured with no further surgical intervention. We measured bronchopulmonary anastomotic flow in 40 patients undergoing coronary artery bypass surgery and the noncoronary collateral blood flow in 27 of these patients. Results from this study show that the bronchopulmonary anastomotic flow for the 40 patients was 140 +/- 182 ml/min (range 8 to 1,043 ml/min), representing 3.23 +/- 4.15 percent of the pump flow (equivalent to the cardiac output), and the noncoronary collateral flow in the 27 patients was 48 +/- 74 ml/min (range 0 to 261 ml/min), representing 1.11 +/- 1.67 percent of the pump flow.
Adult↗
Effect of pulmonary blood flow on leukocyte uptake and release by dog lung.
The effect of pulmonary blood flow on leukocyte uptake and release by the lung was examined in 10 anesthetized spontaneously breathing dogs. Pulmonary arterial and pulmonary venous blood was sampled with catheters placed into the right ventricle and aorta, respectively. Pulmonary blood flow was lowered by inflating a balloon catheter located in the inferior vena cava. In five experiments simultaneous blood samples were drawn from the right ventricle and aorta at 10-s intervals during a control period, a 2- to 3-min period of low flow, and a recovery period. In five additional experiments, less frequent samples were taken over periods of 15-60 min. Total leukocyte concentrations and differential counts were determined for each blood sample. The study shows that large numbers of leukocytes become sequestered within the lung when pulmonary blood flow is low and that an equivalent number of cells are released from the lung after deflation of the balloon catheter. Both the polymorphonuclear leukocytes and the lymphocytes were taken up by the lung when pulmonary blood flow was reduced. We conclude that pulmonary blood flow has a marked effect on the uptake and release of leukocytes by the dog lung.
Animals↗