How much do Indians pay for tuberculosis treatment? A cost analysis

Setting

India's National Tuberculosis Elimination Programme (NTEP) covers diagnostic and therapeutic costs of TB treatment. However, persons living with TB (PLWTB) continue to experience financial distress due to direct costs (payment for testing, treatment, travel, hospitalization, and nutritional supplements) and indirect costs (lost wages, loan interest, and cost of domestic helpers).

Objective

To analyze the magnitude and pattern of TB-related costs from the perspective of Indian PLWTB.

Design

We identified relevant articles using key search terms ('tuberculosis,' 'India,' 'cost,' 'expenditures,' 'financing,' 'catastrophic' and 'out of pocket') and calculated variance-weighted mean costs.

Results

Indian patients incur substantial direct costs (mean: US$46.8). Mean indirect costs (US$666.6) constitute 93.4% of the net costs. Mean direct costs before diagnosis can be up to four-fold that of costs during treatment. Treatment in the private sector can result in costs up to six-fold higher than in government facilities. As many as one in three PLWTB in India experience catastrophic costs.

Conclusion

PLWTB in India face high direct and indirect costs. Priority interventions to realize India's goal of eliminating catastrophic costs from TB include decreasing diagnostic delays through active case finding, reducing the need for travel, improving awareness and perception of NTEP services, and ensuring sufficient reimbursement for inpatient TB care.

Repellent and Attractive Effects of α-, β-, and Dihydro-β- Ionone to Generalist and Specialist Herbivores

In plants, the oxidative cleavage of carotenoid substrates produces volatile apocarotenoids, including α-ionone, β-ionone, and dihydro-β-ionone, compounds that are important in herbivore-plant communication. For example, β-ionone is part of an induced defense in canola, Brassica napus, and is released following wounding by herbivores. The objectives of the research were to evaluate whether these volatile compounds would: 1) be released in higher quantities from plants through the over-expression of the carotenoid cleavage dioxygenase1 (CCD1) gene and 2) cause herbivores to be repelled or attracted to over-expressing plants relative to the wild-type. In vivo dynamic headspace collection of volatiles coupled with gas chromatography-mass spectrometry was used to determine volatile organic compounds (VOC) in the headspace of the Arabidopsis thaliana ecotype Columbia-0 (L.) over-expressing the AtCCD1 gene. The analytical method allowed the detection of β-ionone in the Arabidopsis headspace where emission rates ranged between 2 and 5-fold higher compared to the wild type, thus corroborating the in vivo enhancement of gene expression. A two chamber choice test between wild type and AtCCD1 plants revealed that crucifer flea beetle Phyllotreta cruciferae (Goeze) adults were repelled by the AtCCD1 plants with the highest transcription and β-ionone levels. α-Ionone and dihydro-β-ionone were not found in the headspace analysis, but solutions of the three compounds were tested in the concentration range of β-ionone found in the Arabidopsis headspace (0.05 to 0.5 ng/μl) in order to assess their biological activity with crucifer flea beetle, two spotted spider mite Tetranychus urticae (Koch), and silverleaf whiteflies Bemisia tabaci (Gennadius). Choice bioassays demonstrated that β-ionone has a strong repellent effect toward both the flea beetle and the spider mite, and significant oviposition deterrence to whiteflies. In contrast, dihydro-β-ionone had attractant properties, especially to the crucifer flea beetle, while α-ionone did not show any significant activity. These findings demonstrate how regulating genes of the carotenoid pathway can increase herbivore deterrent volatiles, a novel tool for insect pest management.

Structure and size of bronchopulmonary anastomoses in sheep lung

The distribution and drainage of bronchial arterial blood flow are complex. We used two different methods to study the bronchial-pulmonary anastomoses in sheep lung. Initially, we injected two different sizes of fluorescent microspheres (15 and 100 microm diameter) into the bronchial artery and histologically determined where the different-size microspheres were entrapped in the lung. In a second series of animals, we injected Microfil into the bronchial artery to observe the anastomotic vessels. The microsphere data confirmed the existence of bronchial-to-pulmonary anastomoses. No microspheres were found in the systemic organs (heart and kidney), confirming the absence of large bronchial artery-to-pulmonary vein anastomoses. Unexpectedly, proportionately more large microspheres (100 microm) lodged in the alveolar parenchyma when compared to 15 microm microspheres. This suggests that there are many more small bronchial (< 100 microm) arterioles feeding the airway mucosa than the larger anastomotic vessels feeding into the parenchyma. In the Microfil cast lungs, we observed four types of anastomotic vessels: bronchial arteries/arterioles that anastomose with pulmonary arteries/arterioles that accompany airways; bronchial arterioles that anastomose directly with parenchymal (and eventually alveolar) vessels; bronchial arterioles that anastomose with blood vessels that do not accompany airways; and bronchial arterioles that anastomose with bronchial veins. Based on our in vivo microsphere data, the vessels that do not accompany the airways are most likely bronchial venules, not pulmonary venules.

Soluble gas exchange in the pulmonary airways of sheep

We studied the airway gas exchange properties of five inert gases with different blood solubilities in the lungs of anesthetized sheep. Animals were ventilated through a bifurcated endobronchial tube to allow independent ventilation and collection of exhaled gases from each lung. An aortic pouch at the origin of the bronchial artery was created to control perfusion and enable infusion of a solution of inert gases into the bronchial circulation. Occlusion of the left pulmonary artery prevented pulmonary perfusion of that lung so that gas exchange occurred predominantly via the bronchial circulation. Excretion from the bronchial circulation (defined as the partial pressure of gas in exhaled gas divided by the partial pressure of gas in bronchial arterial blood) increased with increasing gas solubility (ranging from a mean of 4.2 x 10(-5) for SF6 to 4.8 x 10(-2) for ether) and increasing bronchial blood flow. Excretion was inversely affected by molecular weight (MW), demonstrating a dependence on diffusion. Excretions of the higher MW gases, halothane (MW = 194) and SF6 (MW = 146), were depressed relative to excretion of the lower MW gases ethane, cyclopropane, and ether (MW = 30, 42, 74, respectively). All results were consistent with previous studies of gas exchange in the isolated in situ trachea.

Recertification of respiratory therapists' intubation skills one year after initial training: an analysis of skill retention and retraining

Allied health personnel and nonanesthesiologist physicians often undergo training in tracheal intubation but then may actually use the skill relatively infrequently. This study assessed retention of skills one year after initial training and identified specific areas of knowledge critical to successful performance of intubation. Eleven respiratory therapists on the staff of a 253-bed hospital, each of whom had been trained one year previously in airway management, were evaluated. Prior to returning to the operating room for skills assessment and recertification, each respiratory therapist took a 21-question written exam. Therapists then went to the operating room and a trained observer (anesthesiologist) monitored the intubations performed to see whether critical steps were followed, while a second observer monitored a checklist of skills performed. The attending anesthesiologist recertified the therapist only when all steps were correctly performed and the intubation was successful. There was a poor correlation (r = -0.25, p > 0.1) between the number of intubations performed by the therapists for emergencies in the previous year and the number of intubations needed to be recertified. There was a negative correlation (r = -0.8, p < 0.05) between the score on the written test and the number of intubations required for recertification-a higher score meant fewer intubations were needed to achieve recertification. First-pass success occurred significantly more frequently if all skills tested were performed correctly (50/75 first-pass successes had all skills performed correctly vs 10/28 for failed first-pass, p < 0.01). The most common errors were levering the blade on the upper teeth (12/91) and tube not inserted from the right side of the mouth (28/104). When the blade was levered, 8 of 10 intubations failed. When the tube was not inserted from the right side of the face, 6 of 12 failed. The useful findings of this study are: (1) occasional performance of intubation did not ensure skill maintenance; (2) cognitive and procedural abilities correlated, suggesting benefits to study as well as to practical training; and (3) two specific mistakes were associated with a high incidence of failure.

Sleep apnea in adults with traumatic brain injury: a preliminary investigation

OBJECTIVE

To determine the occurrence and nature of sleep-related breathing disorders in adults with traumatic brain injury (TBI).

DESIGN

Prospective, observational, consecutive sample enrollment of subjects admitted for rehabilitation after TBI.

SETTING

Inpatient rehabilitation and subacute rehabilitation units of a tertiary care university medical system.

PARTICIPANTS

Subjects (n = 28) included adults with TBI and a Rancho Los Amigos Scale level of 3 or greater who were less than 3 months postinjury and admitted for comprehensive inpatient rehabilitation.

INTERVENTIONS

Overnight sleep study using portable 6-channel monitoring system.

MAIN OUTCOME MEASURE

Respiratory disturbance index (RDI), which is the number of apneic and hypopneic episodes per hour of sleep.

RESULTS

Evidence of sleep apnea was found in 10 of 28 (36%) subjects as measured by a RDI level of 5 or greater and in 3 of 28 (11%) subjects as measured by a RDI level of 10 or greater. This rate of sleep apnea is significantly (p =.002) higher than would be predicted based on population norms. No correlation was found between the occurrence of significant sleep apnea and measures of TBI severity or other demographic variables. Sleep-related breathing disorders were primarily central though obstructive apneas were also noted.

CONCLUSION

In this preliminary investigation, sleep-related breathing disorders as defined by a respiratory disturbance index of 5 or greater appears to be common in adult subjects with TBI.

Pulmonary and bronchial circulatory responses to segmental lung injury

In regional lung injury, pulmonary blood flow decreases to the injured regions, and anastomotic bronchial blood flow and total bronchial blood flow increase. However, the pattern of redistribution of the two blood flows to the injured and noninjured areas is not known. In six anesthetized sheep, pulmonary and bronchial blood flows were measured with 15-microm fluorescent microspheres by using the reference flow method. Blood flows were measured in the control state and 1 h after instilling 1 ml/kg of 0. 1 N hydrochloric acid into a dependent segment of the left lung. The lungs were then removed, dried, and cubed into approximately 2-cm cubes while spatial coordinates were noted. Blood flow to each piece was calculated. Mean pulmonary blood flow to the noninjured pieces went from 730 +/- 246 to 574 +/- 347 ml/min (P = 0.22), whereas in the injured pieces the pulmonary blood flow decreased from 246 +/- 143 to 56 +/- 46 ml/min (P < 0.01). In contrast, bronchial blood flow to the injured pieces increased from 0.51 +/- 0.1 to 1.43 +/- 0. 85 ml/min (P = 0.005). We measured the change in flow as it related to the distance from the center of the injured area. Pulmonary blood flow decreased most at the center of the injury, whereas bronchial blood flow doubled at the center of injury and decreased with the distance away from the injury. The absolute increase in bronchial blood flow was substantially less than the decrease in pulmonary blood flow in the injured pieces. We also partitioned the observed variation in pulmonary and bronchial blood flow into that attributable to structure and that due to lung injury and found that 48% of the variation in pulmonary blood flow could be attributed to structure, whereas in the bronchial circulation 70% was attributable to structure. The reasons for these differences are not known and may reflect the intrinsic properties of the systemic and pulmonary circulations.

Effect of aerosolized acetylcholine on bronchial blood flow

We studied the effects of aerosolized as well as intravenous infusion of acetylcholine on bronchial blood flow in six anesthetized sheep. Intravenous infusion of acetylcholine, at a dose of 2 microg/kg, increased bronchial blood flow from 45 +/- 15 (SE) to 74 +/- 30 ml/min, and vascular conductance increased by 76 +/- 22%. In contrast, aerosolized acetylcholine at doses of 2 and 20 microg/kg decreased bronchial vascular conductance by approximately 10%. At an aerosolized dose of 200 microg/kg, the bronchial vascular conductance increased by approximately 15%, and there was no further increase in conductance when the aerosolized dose was increased to 2,000 microg/kg. Pretreatment of animals with a nitric oxide synthase inhibitor, Nomega-nitro-L-arginine methyl ester hydrochloride, partially blocked the vasodilatory effects of intravenous acetylcholine and completely blocked the vasodilatory effects of high-dose aerosolized acetylcholine. These data suggest that aerosolized acetylcholine does not readily penetrate the vascular wall of bronchial circulatory system and, therefore, has minimal vasodilatory effects on the bronchial vasculature.

Efficacy and safety of a 10-day course of 400 or 600 milligrams of grepafloxacin once daily for treatment of acute bacterial exacerbations of chronic bronchitis: comparison with a 10-day course of 500 milligrams of ciprofloxacin twice daily

A randomized, prospective, double-blind, double-dummy, multicenter study investigated the efficacy and safety of 10 days of oral therapy with grepafloxacin at 400 mg once daily, grepafloxacin at 600 mg once daily, or ciprofloxacin at 500 mg twice daily in 624 patients with acute bacterial exacerbations of chronic bronchitis. At the end of treatment, clinical success (cure or improvement) was achieved for 93% (140 of 151), 88% (137 of 156), and 91% (145 of 160) of patients in the groups receiving grepafloxacin at 400 mg, grepafloxacin at 600 mg, and ciprofloxacin, respectively (clinically evaluable population). At follow-up (14 to 28 days posttreatment), the clinical success rates were 87% (124 of 143), 81% (122 of 151), and 80% (123 of 154) in the groups receiving grepafloxacin at 400 mg and 600 mg and ciprofloxacin, respectively. A total of 379 pathogens were isolated from 290 patients, with the most common isolates being Moraxella catarrhalis (21%), Staphylococcus aureus (20%), Haemophilus influenzae (18%), and Streptococcus pneumoniae (7%). For the evaluable population, successful bacteriologic response was obtained at the end of treatment for 96% (92 of 96), 98% (87 of 89), and 92% (82 of 90) of patients receiving grepafloxacin at 400 mg, grepafloxacin at 600 mg, and ciprofloxacin, respectively, and was maintained in 86% (82 of 95), 88% (78 of 89), and 82% (69 of 84) of patients, respectively, at follow-up. All pretreatment S. pneumoniae isolates were susceptible to grepafloxacin, but two strains were resistant to ciprofloxacin. All treatments were well tolerated, with the most frequently reported drug-related adverse events being nausea, taste perversion, and headache. All drug-related adverse events in the grepafloxacin groups were mild or moderate in severity. This study demonstrates that 10-day courses of grepafloxacin given at 400 or 600 mg once daily were as effective, clinically and bacteriologically, as ciprofloxacin given at 500 mg twice daily for the treatment of acute bacterial exacerbations of chronic bronchitis.

Nitric oxide and beta-adrenergic agonist-induced bronchial arterial vasodilation

In anesthetized sheep, we measured bronchial blood flow (Qbr) by an ultrasonic flow probe to investigate the interaction between inhaled nitric oxide (NO; 100 parts/million) given for 5 min and 5 ml of aerosolized isoetharine (1.49 x 10(-2) M concentration). NO and isoetharine increased Qbr from 26.5 +/- 6.5 to 39.1 (SE) +/- 10.6 and 39.7 +/- 10.7 ml/min, respectively (n = 5). Administration of NO immediately after isoetharine further increased Qbr to 57.3 +/- 15.1 ml/min. NO synthase inhibitor N(omega)-nitro-L-arginine methyl ester hydrochloride (L-NAME; 30 mg/kg, in 20 ml saline given i.v.) decreased Qbr to 14.6 +/- 2.6 ml/min. NO given three times alternately with isoetharine progressively increased Qbr from 14.6 +/- 2.6 to 74.3 +/- 17.0 ml/min, suggesting that NO and isoetharine potentiate vasodilator effects of each other. In three other sheep, after L-NAME three sequential doses of isoetharine increased Qbr from 10.2 +/- 3.4 to 11.5 +/- 5.7, 11.7 +/- 4.7, and 13.3 +/- 5.7 ml/min, respectively, indicating that effects of isoetharine are predominantly mediated through synthesis of NO. When this was followed by three sequential administrations of NO, Qbr increased by 146, 172, and 185%, respectively. Thus in the bronchial circulation, there seems to be a close interaction between adenosine 3',5'-cyclic monophosphate- and guanosine 3',5'-cyclic monophosphate-mediated vasodilation.

Bronchial circulation in the marsupial opossum, Didelphis marsupialis

This study characterizes the existence of a bronchial circulation in a marsupial, an animal which does not undergo placental development and does not have a ductus arteriosus. Direct perfusion of the lung by the pulmonary vasculature during the fetal development of opossums may occur, potentially eliminating the need for a bronchial circulation. We used radio- and fluorescent-labeled microspheres in conjunction with postmortem intravascular casting to determine if opossums have a systemic (bronchial) blood supply to the lung (n = 9). Gross postmortem examination of the intravascular casts showed a well-developed common bronchial artery. The histological distribution pattern of fluorescent microspheres was primarily to the airways. A few fluorescent microspheres were observed in the alveolar capillaries, indicating that a precapillary bronchial-to-pulmonary anastomosis exists in the opossum. Using the reference flow technique, total bronchial blood flow to the left lung averaged 0.95 +/- 0.58 SE ml/min. The presence of a bronchial circulation in the opossum suggests that it is more than a vestigial structure from embryonic development, potentially supporting its functional importance for carrying nutrients to the airway.

Distribution of pulmonary and bronchial blood supply to airways measured by fluorescent microspheres

This study determined the relative contributions of systemic (bronchial) and pulmonary blood flow to the intraparenchymal airways >1 mm in diameter by using 15-mu m fluorescent microspheres and fluorescence microscopy in four dogs. Fluorescent microspheres of one color were injected into the inferior vena cava as a pulmonary blood flow marker, and fluorescent microspheres of another color were injected into the left ventricle as a systemic blood flow marker. After the second injection, the animals were killed and the lungs were excised and air dried at total lung capacity. The left lung was sliced into transverse planes and then sectioned into smaller blocks containing airways down to 1 mm in diameter. The blocks were then sectioned using a Vibratome and examined with a fluorescence microscope. Pulmonary and systemic blood flow markers were counted in airway walls, and the diameter of each airway was measured to determine the bronchial tissue volume. After a correction for the number of blood flow markers injected into each circulation, the average ratio of pulmonary to systemic blood flow markers seen in airway walls was 1:37, indicating that 97% of the blood supply to the intraparenchymal airways down to 1 mm in diameter was from the bronchial circulation. Furthermore, on the basis of a weighted least squares regression analysis, systemic (bronchial) blood flow per unit tissue volume increased as airway diameter decreased (P = 0.03).

Trypsinogen and other pancreatic enzymes in patients with renal disease: a comparison of high-efficiency hemodialysis and continuous ambulatory peritoneal dialysis

Although serum amylase and lipase levels have been studied extensively in patients with renal disease, there are fewer data regarding trypsinogen levels in patients with end-stage renal disease (ESRD) treated with different dialytic modalities. We therefore evaluated the blood concentrations of trypsinogen, amylase, and lipase in asymptomatic patients with chronic renal insufficiency (CRI) and ESRD, to determine whether treatment modality or renal handling of these enzymes is important in determining steady-state levels in asymptomatic patients with chronic renal disease. Mean trypsinogen concentration levels were higher in hemodialysis (HD) patients and patients with CRI compared with normal subjects when values in the different groups were compared. There was no difference in the mean trypsinogen levels between patients treated with HD and those with CRI, between patients treated with chronic ambulatory peritoneal dialysis (CAPD) and those treated with HD, or between CAPD patients and patients with CRI. The mean circulating trypsinogen concentration was elevated more frequently and to a higher level than amylase or lipase in patients with CRI and ESRD. HD treatment did not result in a lowering of mean circulating pancreatic enzyme levels. We propose that decreased peripheral clearance, pancreatic overproduction, increased release from the pancreas, or a combination of these mechanisms is responsible, at least in part, for the increased plasma concentration of trypsinogen in patients with CRI, rather than simply a decrease in renal clearance.

Positive end expiratory pressure reduces bronchial blood flow after aspiration injury

We hypothesized that since added airway pressure compresses bronchial vessels, the airway hyperemia found following airway injury would be reduced by positive end-expiratory pressure (PEEP). Accordingly, we measured the effect of 15 cm H2O PEEP on bronchial and pulmonary blood flows by the radioactive microsphere reference flow technique in closed chested goats (n = 7) before and after aspiration injury to the left lung with 0.1 N HCl. Thirty minutes after aspiration, the pulmonary blood flow to the injured left lung was reduced by one third, whereas the total bronchial blood flow to the left lung (normalized to mean systemic pressure of 100 torr) doubled (11.3 +/- 2.2 to 20.6 +/- 1.0 ml/min 100 torr; p < 0.01). Increasing PEEP from 5 to 15 cm H2O decreased total bronchial blood flow by about half both before (11.3 +/- 2.2 falling to 5.7 +/- 1.4 ml/min/100 torr) and after injury (20.6 +/- 1.0 falling to 10.3 +/- 2.7 ml/min/100 torr). The airway portion (down to 2-3 mm airways) of the total bronchial blood flow of the injured lung increased more than three-fold (1.4 +/- 0.5 rising to 5.5 +/- 1.3 ml/min/100 torr; p < 0.01). This increased flow after aspiration was less affected by PEEP of 15 cm H2O (5.5 +/- 1.3 to 2.8 +/- 0.7 ml/min/100 torr, p = 0.09) than before injury (1.4 +/- 0.5 falling to 0.5 +/- 0.1 ml/min/100 torr; p < 0.05). The increase of the parenchymal portion of the bronchial blood flow after injury, although apparent (9.9 +/- 1.8 increasing to 15.1 +/- 1.2 ml/min/100 torr), was not significant (p = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of low-dose endotoxin on pulmonary vascular permeability following acute hemorrhagic shock

The purpose of the current study was to determine the effect of low-dose Escherichia coli lipopolysaccharide (LPS) on pulmonary vascular permeability when administered after hemorrhagic shock (40% of baseline cardiac output) followed by resuscitation. Animals were monitored for 3-4 h after LPS infusion. Thirty minutes prior to termination of the experiment, 3 mCi of 125I-human serum albumin was injected intravenously to calculate a permeability index from the left lung lavage and plasma 125I ratios. The two control groups were (1) shock only (no LPS, n = 4), and (2) LPS only (no shock, n = 8). The permeability index for the shock-only group was 0.0015 +/- 0.0007 (mean +/- SE) and that for the LPS-only group was 0.0035 +/- 0.0014. The permeability index for the experimental group (shock followed by LPS, n = 10) was 0.0071 +/- 0.0030 (p > 0.05). Similarly, there was no difference in the wet-to-dry ratios between the three groups. The shock+LPS group required more intravenous fluids to maintain mean arterial blood pressure at control values than the LPS-only group (p < 0.003). We conclude that hemorrhagic shock and resuscitation do not lead to an acute increased permeability of the lung when it is subsequently challenged by a low dose of bacterial LPS.

Acute inhalation injury

Toxic inhalants cause injury through a variety of different mechanisms, including direct irritation of the respiratory tract mucosa, asphyxiation, and systemic absorption of the toxin. The nature and extent of the acute injury depends on the inhalant's water solubility, aerodynamic features, pH, and concentration. In addition, a patient's underlying respiratory function may affect the clinical response. Smoke inhalation is a particularly challenging clinical problem because patients often are exposed to a large number of inhaled toxins and may suffer thermal injury to the respiratory tract as well. Several chronic respiratory problems have been identified following acute inhalation injuries. Chronic airflow obstruction has been reported in patients exposed to ammonia, chlorine, nitrogen dioxide, and sulfur dioxide; bronchiolitis obliterans may follow exposure to nitrogen dioxide and sulfur dioxide. Inhalation injuries can be difficult to manage because exposures occur infrequently, and the exact toxic agents involved often are not known immediately. Prevention of occupational exposures remains a cornerstone in the overall management of inhalation injuries.

Fifteen micrometer microspheres reflux up the pulmonary veins during pulmonary artery occlusion

The systemic arterial blood supply to the lung (bronchial blood flow, Qbr) is commonly measured using the reference flow technique by injecting radiolabeled microspheres into the left atrium (LA) and simultaneously collecting a reference blood sample from a large artery such as the aorta. These measurements are often done with the pulmonary artery occluded prior to the time of injection. We have reported previously that left atrial blood refluxes up the pulmonary veins following pulmonary artery (PA) occlusion. We designed this experiment to determine if 15 mu microspheres reflux from the LA into the left lung (i) when the left PA is occluded prior to microsphere injection and (ii) when the left PA is open during the injection. We calculated Qbr to the left lung after simultaneous left ventricular (LV) and LA injections of different radiolabeled microspheres in anesthetized, closed-chest, prone goats. When the PA was open (but occluded 5 sec after the microsphere injection), Qbr calculated from an LA injection differed little from that calculated from an LV injection of microspheres. However, when the PA was occluded prior to injection of the microspheres, Qbr calculated from an LA injection was significantly higher than that calculated from an LV injection suggesting that microspheres reflux from the LA to the lung.

Influence of lung volume and alveolar pressure on reverse pulmonary venous blood flow

We have reported that left atrial blood refluxes through the pulmonary veins to gas-exchanging tissue after pulmonary artery ligation. This reverse pulmonary venous flow (Qrpv) was observed only when lung volume was changed by ventilation. This was believed to drive Qrpv by alternately distending and compressing the alveolar and extra-alveolar vessels. Because lung and pulmonary vascular compliances change with lung volume, we studied the effect of positive end-expiratory pressure (PEEP) on the magnitude of Qrpv during constant-volume ventilation. In prone anesthetized goats (n = 8), using the right lung to maintain normal blood gases, we ligated the pulmonary and bronchial arterial inflow to the left lung and ventilated each lung separately. A solution of SF6, an inert gas, was infused into the left atrium. SF6 clearance from the left lung was determined by the Fick principle at 0, 5, 10, and 15 and again at 0 cmH2O PEEP and was used to measure Qrpv. Left atrial pressure remained nearly constant at 20 cmH2O because the increasing levels of PEEP were applied to the left lung only. Qrpv was three- to fourfold greater at 10 and 15 than at 0 cmH2O PEEP. At these higher levels of PEEP, there were greater excursions in alveolar pressure for the same ventilatory volume. We believe that larger excursions in transpulmonary pressure during tidal ventilation at higher levels of PEEP, which compressed alveolar vessels, resulted in the reflux of greater volumes of left atrial blood, through relatively noncompliant extra-alveolar veins into alveolar corner vessels, and more compliant extra-alveolar arteries.

Improvement in mood, physical symptoms, and function with nortriptyline for depression in patients with chronic obstructive pulmonary disease

Although recent epidemiologic studies have established that patients with chronic medical illness and depressed mood are more disabled than euthymic patients, detailed data on the benefits and risks of antidepressant treatment in medically high-risk patients have been slow to accumulate. The authors have examined multiple outcome indicators in patients with disabling chronic obstructive pulmonary disease and comorbid depression. Thirty patients completed a 12-week, randomized controlled trial of nortriptyline. Nortriptyline was clearly superior to placebo for treatment of depression. Nortriptyline treatment was accompanied by marked improvements in anxiety, certain respiratory symptoms, overall physical comfort, and day-to-day function; placebo effects were negligible. Physiological measures reflecting pulmonary insufficiency were generally unaffected by treatment. These data provide impetus for renewed efforts to improve recognition and treatment of mood disorders in even severely disabled medical patients.

Comparison of estimates of cardiac output by indicator dilution and freon 22 uptake during gas mixing in dogs

STUDY OBJECTIVE

The aim was to measure cardiac output while rebreathing tidal volumes, by correction of soluble gas uptake for gaseous mixing.

DESIGN

Simultaneous measurements of cardiac output by indocyanin green and freon 22 uptake during rebreathing were made. Mixing for a hypothetical gas of identical gaseous diffusivity to freon 22 was calculated by interpolation between concentrations of two insoluble gases, helium and sulphur hexafluoride. Mixing efficiency was estimated by the number of breaths for helium to become 99% equilibrated with lung gas (n99-He).

EXPERIMENTAL MATERIAL

Five anaesthetised dogs rebreathed at intervals with 300 ml of test gas.

MEASUREMENTS AND MAIN RESULTS

63 comparisons of cardiac output using indocyanin green and freon 22 uptake (over breaths 7-13 using the mean mixed volume of distribution), gave a mean (95% confidence interval) underestimation of 0.345 (0.093-0.597) litre.min-1 (14%). Exclusion of 12 points in which n99-He was greater than 15 resulted in a mean underestimation of 0.052(-0.163-0.267) litre.min-1 (2%). Without correction for gaseous mixing, freon 22 uptake for these data overestimated blood flow by a mean of 1.31 litre.min-1 (overestimation = 2.7 over breaths 5-11). Use of the equilibrium volume of distribution resulted in an overestimation of blood flow relative to green dye of 1.2 litre.min-1 (breaths 5-11) and 0.76 litre.min-1 (breaths 7-13).

CONCLUSIONS

Estimates of cardiac output by soluble gas uptake are optimal when correction is made for mixing of gas of identical diffusivity. The mean mixed gas volume gives the best correlation with the reference method, implying a selective distribution of blood flow to the better ventilated areas.

Influence of lung volume and left atrial pressure on reverse pulmonary venous blood flow

Infarction of the lung is uncommon even when both the pulmonary and the bronchial blood supplies are interrupted. We studied the possibility that a tidal reverse pulmonary venous flow is driven by the alternating distension and compression of alveolar and extra-alveolar vessels with the lung volume changes of breathing and also that a pulsatile reverse flow is caused by left atrial pressure transients. We infused SF6, a relatively insoluble inert gas, into the left atrium of anesthetized goats in which we had interrupted the left pulmonary artery and the bronchial circulation. SF6 was measured in the left lung exhalate as a reflection of the reverse pulmonary venous flow. No SF6 was exhaled when the pulmonary veins were occluded. SF6 was exhaled in increasing amounts as left atrial pressure, tidal volume, and ventilatory rates rose during mechanical ventilation. SF6 was not excreted when we increased left atrial pressure transients by causing mitral insufficiency in the absence of lung volume changes (continuous flow ventilation). Markers injected into the left atrial blood reached the alveolar capillaries. We conclude that reverse pulmonary venous flow is driven by tidal ventilation but not by left atrial pressure transients. It reaches the alveoli and could nourish the alveolar tissues when there is no inflow of arterial blood.

The effect of bronchial venous pressure on pulmonary edema in the dog

We examined the effect of elevating systemic venous pressure on the rate of edema formation in the left lower lobes (LLL) of anesthetized, open-chested dogs. The pulmonary circulation of the LLL was isolated using cannulae in the artery and vein which were attached to blood-filled reservoirs. The LLL was distended to an alveolar pressure of 25 cm H2O with 5% CO2 and air, and suspended from a strain gauge which allowed continuous weight recording. The pulmonary vascular pressures were raised so all of the LLL was in zone III. The rate of weight change occurring over the last 4 minutes of a 6 minute period of this pulmonary vascular pressure rise was taken to represent the control transvascular fluid flux. The rate of weight gain of the LLL was then determined with the same pulmonary vascular pressure elevation only when downstream bronchial venous pressure alone, downstream lymphatic pressure alone, or when both downstream lymphatic and bronchial venous pressures were elevated. The transvascular fluid flux was increased when downstream bronchial venous pressure was elevated. When only downstream lymphatic pressure was elevated there was no augmentation of transvascular fluid flux. These findings suggest that when a lung is already subjected to raised pulmonary vascular pressure sufficient to cause edema, acute elevation of bronchial systemic venous pressure augments the net rate of outward fluid flux, while downstream lymphatic pressure elevation does not.

The drainage routes of the bronchial blood flow in anesthetized dogs

It is generally accepted that the bronchial blood flow from extrapulmonary airways drains to the systemic veins through the bronchial veins, while that from the intrapulmonary airways drains into the pulmonary vasculature and eventually the left heart. This concept has not been confirmed by physiologic studies in live animals. We measured the routes taken by radionuclide-labeled Diethylenetriamine pentaacetate (DTPA) deposited in the extrapulmonary and the intrapulmonary airways in dogs. In living, anesthetized open chest animals, the pulmonary circulation of the left lower lobe was isolated and perfused with autologous heparinized blood. 99mTc DTPA was deposited on the mucosa of the extrapulmonary left mainstem bronchus just beyond the main carina (extrapulmonary deposition) and 111In DTPA on that of an intrapulmonary left lower lobe segmental bronchus (intrapulmonary deposition). Sequential blood samples from the right heart and from the isolated left lower lobe pulmonary circuit were counted for radioactivity, corrected for the volume in which they were distributed and for the bronchial blood that flowed into the isolated left lower lobe circuit, and expressed as the ratio of systemic to pulmonary drainage from each deposition site. The extrapulmonary tracer drained mostly to the systemic veins (84% of total) but also into the pulmonary circulation (16% of total). The intrapulmonary tracer drained mostly into the pulmonary circulation (70% of total) but also into the right heart (30% of total). Since tracers from both deposition sites drained to both circulations, the bronchial vasculature is continuous between the systemic (right heart) and the pulmonary circulation. Thus, it may provide a pathway for blood flow between the right and left heart.

The pulmonary sequelae associated with accidental inhalation of chlorine gas

Twenty previously healthy individuals were accidentally exposed to high concentrations of chlorine gas in 1975. Pulmonary function tests were performed on these individuals on several occasions over the next 12 years. On average, each subject was followed up for 8.5 years and 13 of the 20 exposed persons were tested 12 years following the exposure. Pulmonary function tests obtained one day following the accident were most notable for the high prevalence of airflow obstruction and air trapping. Over the ensuing years, the airflow obstruction persisted; however, the high prevalence of air trapping resolved. Of note, the prevalence of a low residual volume consistently increased during the follow-up period (p less than 0.001) and at year 12, 67 percent of those tested had residual volumes below 80 percent of their predicted value. We also found that five of 13 subjects tested at year 12 had an increase in airway reactivity (greater than 15 percent decline in FEV1) to inhaled methacholine. Those individuals with reactive airways were older (p = 0.004) and had more marked airflow obstruction (p = 0.03) and air trapping (p = 0.03) immediately following the exposure. These data suggest that exposure to high concentrations of chlorine gas may result in long-term pulmonary complications that are characterized by a reduced residual volume. Unfortunately, these data preclude us from determining whether the chlorine exposure led to the development of airway reactivity or the presence of reactive airways accounted for the air trapping that was observed following the exposure to chlorine gas.

Vagal cooling and positive end-expiratory pressure reduce systemic to pulmonary bronchial blood flow in dogs

Positive end-expiratory pressure (PEEP) reduces systemic to pulmonary bronchial blood flow [Qbr(s-p)] presumably because it increases bronchial vascular resistance. Since PEEP increases lung volume and thus could stimulate pulmonary stretch receptors, we investigated the hypothesis that the PEEP-related decrease in bronchial blood flow was due to a reflex mediated by the vagus. In open-chest dogs the left lower lobe (LLL) was isolated, independently ventilated, perfused in situ with a closed pulmonary vascular circuit and weighed continuously. Qbr(s-p) was measured as LLL vascular circuit overflow and changes in LLL weight. When LLL PEEP was increased from 5 to 15 cm H2O in a group of 11 dogs Qbr(s-p) was reduced by half from 60.8 +/- 10.5 to 31.6 +/- 6.1 ml/min/100 g dry lobe weight. In another group of 7 dogs Qbr(s-p) was 46.5 +/- 6.9 with PEEP = 5 cm H2O; it decreased to 28.3 +/- 6.8 with bilateral cervical vagal cooling (0-1.5 degrees C) and did not decrease further after increasing PEEP to 15 cm H2O. We conclude that the effect of resting vagal tone is to increase Qbr(s-p) and that the effect of PEEP on Qbr(s-p) may be mediated at least partially by vagal influences.

The effect of diet or exercise on plasma norepinephrine kinetics in moderately obese young men

An increase in sympathetic nervous system (SNS) activity in the obese has been described by some but not all investigators. It is possible that an increase in SNS tone may play a role in the predisposition to atherosclerotic cardiovascular disease noted in the obese. The effect of dietary weight loss or exercise training on resting SNS activity in moderately obese subjects has not been extensively studied and the results of previous studies are conflicting. Therefore, we prospectively evaluated resting SNS activity in healthy moderately obese subjects randomized to either a three month dietary weight loss (n = 13) or endurance exercise training (n = 18). All subjects were weight stabilized on a constant composition diet for 10 days prior to study both before and after the interventions. Although both groups lost weight, weight loss was greater in the diet group (-13.6 +/- 6.7 vs -2.3 +/- 3.4 kg, P less than 0.001). The composition of weight loss was also different with 32 percent of total weight loss as fat free mass (FFM) in the dieters compared to no significant change in FFM in the exercisers. The caloric requirement for weight stabilization declined after the diet but increased following exercise training (-247 vs + 202 kcal/day, P less than 0.001). No significant changes in blood pressure occurred in either group, and neither group had a significant change in resting plasma norepinephrine concentration. Plasma epinephrine concentrations were also unchanged. However, SNS activity as reflected by arterialized plasma NE kinetics revealed that NE appearance rate declined by 17 percent after dietary weight loss (P less than 0.01), but was not significantly changed after exercise training. These results suggest that dietary weight loss is more effective than exercise training in reducing overall resting SNS activity in normotensive subjects. Since exercise training is known to reduce the SNS response to a given submaximal workload, a combination of diet plus exercise might be the most effective way to reduce overall SNS activity and its possible role in the premature atherosclerosis associated with obesity.

Pulmonary artery infusion of prostacyclin increases lobar bronchial blood flow

Intrapulmonary systemic to pulmonary bronchial blood flow [Qbr (s-p)] decreases with administration of cyclooxygenase inhibitors. This effect may be due to a decrease in the production of vasodilating prostaglandins and reflect either a decrease in the total intrapulmonary bronchial blood flow (Qbr), or a redistribution of the intrapulmonary systemic venous return. In nine open chested dogs the left lower lobe (LLL) was isolated and perfused in situ. Blood flow to the extrapulmonary airways (Qep), and Qbr were measured by the reference flow technique. Qbr (s-p) was measured as the overflow from the closed LLL perfusion circuit. After ibuprofen, PG-I2 was infused into the LLL PA and the Qbr (s-p) was continuously monitored. Qbr, and Qep were measured before and after ibuprofen, and during and after the PG-I2 infusion. The upstream pressure for Qbr (s-p) was estimated with and without PG-I2 infusion. After ibuprofen the Qep, Qbr, and Qbr (s-p) fell to 45, 22, and 17%, respectively, of the pre-ibuprofen values (P less than 0.05). PG-I2 increased the Qbr (s-p) and Qbr (P less than 0.05), while Qep was unchanged. During all experimental conditions the simultaneous measurements of Qbr and Qbr (s-p) were not different from each other (P less than 0.001). The upstream pressure for Qbr (s-p) increased from 30 to 50 cm H2O (P less than 0.05). Intralobar bronchial blood flow is drained almost entirely through the pulmonary circulation, and PG-I2 in the LLL pulmonary circulation increases systemic blood flow to the LLL, probably acting at the level of a systemic arteriole.

Bronchial circulation and cyclooxygenase products in acute lung injury

The role of cyclooxygenase products in the response of the bronchial circulation to acute lung injury was examined in 30 dogs. By use of an open-chest preparation the left lower lobe (LLL) pulmonary circulation was isolated, continuously weighed, and perfused in situ. The anastomotic bronchial blood flow [Qbr(s-p)] was measured as the rate of increase in the volume of the LLL-perfusion circuit. Four groups of dogs were studied. In group A, six dogs received cyclooxygenase inhibition (COI) with either indomethacin (2 mg/kg) or ibuprofen (10 mg/kg). In group B (n = 10) lung injury caused by airway instillation of glucose (15 mg) with glucose oxidase (500 micrograms/kg) (G/GO) or LLL pulmonary arterial infusion of alpha-napthyl thiourea (ANTU, 2 mg/kg). Group C (n = 10) received COI, and 30 min later injury was induced as above with either ANTU or G/GO. Group D (n = 4) received COI immediately after anesthesia; then, 30 min after completion of the surgical preparation, injury was induced with ANTU or G/GO. After COI, Qbr(s-p) decreased to 35 +/- 9% of the basal values (P less than 0.05). After administration of ANTU or G/GO, Qbr(s-p) increased irrespective of whether COI was present. 6-Ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TxB2) were measured by radioimmunoassay in the LLL pulmonary artery and systemic venous blood, demonstrating an increase in 6-keto-PGF1 alpha due to surgical preparation and confirming complete COI in those animals receiving COI immediately after anesthesia. These findings demonstrate that 1) the bronchial circulation is capable of a sevenfold increase in flow in response to acute lung injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Upstream pressure for systemic to pulmonary flow from bronchial circulation in dogs

Systemic to pulmonary flow from bronchial circulation, important in perfusing potentially ischemic regions distal to pulmonary vascular obstructions, depends on driving pressure between an upstream site in intrathoracic systemic arterial network and pulmonary vascular bed. The reported increase of pulmonary infarctions in heart failure may be due to a reduction of this driving pressure. We measured upstream element for driving pressure for systemic to pulmonary flow from bronchial circulation by raising pulmonary venous pressure (Ppv) until the systemic to pulmonary flow from bronchial circulation ceased. We assumed that this was the same as upstream pressure when there was flow. Systemic to pulmonary flow from bronchial circulation was measured in left lower lobes (LLL) of 21 anesthetized open-chest dogs from volume of blood that overflowed from pump-perfused (90-110 ml/min) pulmonary vascular circuit of LLL and was corrected by any changes of LLL fluid volume (wt). Systemic to pulmonary flow from bronchial circulation upstream pressure was linearly related to systemic arterial pressure (slope = 0.24, R = 0.845). Increasing Ppv caused a progressive reduction of systemic to pulmonary flow from bronchial circulation, which stopped when Ppv was 44 +/- 6 cmH2O and pulmonary arterial pressure was 46 +/- 7 cmH2O. A further increase in Ppv reversed systemic to pulmonary flow from bronchial circulation with blood flowing back into the dog. When net systemic to pulmonary flow from bronchial circulation by the overflow and weight change technique was zero a small bidirectional flow (3.7 +/- 2.9 ml.min-1 X 100 g dry lobe wt-1) was detected by dispersion of tagged red blood cells that had been injected.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute increases in anastomotic bronchial systemic to pulmonary blood flow due to generalized lung injury

Since pulmonary blood flow to regions involved in adult respiratory disease syndrome (ARDS) is reduced by hypoxic vasoconstriction, compression by cuffs of edema, and local thromboses, we postulated that the bronchial circulation must enlarge to provide for the inflammatory response. We measured anastomotic bronchial systemic to pulmonary blood flow [QBr(s-p)] serially in a lung lobe in 31 open-chest dogs following a generalized lobar injury simulating ARDS. The pulmonary circulation of the weighed left lower lobe (LLL) was isolated and perfused (zone 2) with autologous blood in anesthetized dogs. QBr(s-p) was measured from the amount of blood which overflowed from this closed vascular circuit corrected by any changes in the lobe weight. The LLL was ventilated with 5% CO2 in air. The systemic blood pressure (volume infusion), gases, and acid-base status (right lung ventilation) were kept constant. We injured the LLL via the airway by instilling either 0.1 N HCl or a mixture of glucose and glucose oxidase or via the pulmonary vessels by injecting either alpha-naphthylthiourea or oleic acid into the LLL pulmonary artery. In both types of injury, there was a prompt rise in QBr(s-p) (mean rise = 247% compared with control), which was sustained for the 2 h of observation. The cause of this increase in flow was studied. Control instillation of normal saline into the airways or into the pulmonary vessels did not change QBr(s-p) nor did a similar increase in lobar fluid (weight) due to hydrostatic edema. Neither cardiac output nor systemic blood pressure increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of inhaled albuterol powder and aerosol in asthma

In this multicenter, randomized, double-blind study comparing the efficacy and safety of aerosolized albuterol with the dry powder formulation, 231 patients with chronic reversible obstructive airway disease were randomly allocated to receive either placebo albuterol aerosol followed immediately by active albuterol powder (200 micrograms) or active albuterol aerosol (two puffs, 180 micrograms) followed immediately by placebo lactose powder four times a day for a period of 12 weeks. No statistically significant differences were found between the powder and aerosol formulations with respect to pulmonary function, length of time mean FEV1 remained greater than or equal to 15% above baseline, physicians' assessments of patients' clinical response, or patients' subjective symptom scores. There were also no significant differences between treatment groups in cardiovascular effects, laboratory values, or adverse events. Among patients who expressed a preference for one of the delivery systems, half preferred using the powder. Results of this study demonstrate that 200 micrograms of albuterol powder is as safe and effective as 180 micrograms of albuterol aerosol.

Ipratropium bromide in chronic bronchitis/emphysema. A review of the literature

Many studies have evaluated the efficacy of ipratropium bromide in chronic obstructive pulmonary disease (COPD). Single-agent studies have shown ipratropium to be both safe and effective in COPD. Several studies have compared ipratropium with sympathomimetic agents or methylxanthines in patients with chronic bronchitis or emphysema; all of these studies have shown at least an equal, and in most instances a superior, bronchodilator action with ipratropium in terms of duration of action as well as peak bronchodilator effect in patients with COPD. In some patients with COPD, beta agonists, theophylline, or corticosteroids may have some additive, but not synergistic, bronchodilator effects when given with ipratropium.

Hypoxia and hypercarbia increase bronchial blood flow through bronchopulmonary anastomoses in anesthetized dogs

We studied the effect of systemic hypoxemia and hypercarbia on the bronchial blood flow in open-chested, anesthetized dogs. The pulmonary artery and vein of the left lower lobe (LLL) were isolated with cannulas and connected to reservoirs set at atmospheric pressure relative to the base of the LLL. That fraction of the bronchial arterial flow (Qbr) to the LLL, which flowed through the bronchopulmonary anastomoses into these reservoirs, was continuously measured. The LLL was inflated continuously with 6% CO2 and air at a constant alveolar pressure of 10 cm H2O. Systemic arterial O2 tension (PaO2) and arterial CO2 tension (PaCO2) were varied by separately ventilating the right lung through a bifurcated endotracheal tube. A 10-min period was allowed for stabilization after each change in experimental condition. Anastomotic Qbr was measured for 5 min during each experiment. In separate animals, similar studies were performed before and 30 min after intravenously administered indomethacin (6 mg/kg body weight). During normoxic conditions when PaO2 was 79 +/- 8 torr (mean +/- SEM), the mean anastomotic Qbr was 5.7 +/- 2.0 ml/min (n = 9). This flow increased to 8.3 +/- 2.5 ml/min (p less than 0.05) during hypoxemic conditions (PaO2, 38 +/- 3). The anastomotic Qbr increased from 5.8 +/- 1 to 9.0 +/- 2 ml/min (p less than 0.005) when PaCO2 was increased from 23 +/- 1 to 47 +/- 2 torr (n = 11). Pretreatment with intravenously administered indomethacin blocked both the hypoxemia-induced (n = 4) and hypercarbia-induced (n = 4) increases in anastomotic Qbr. We conclude that both hypoxemia and hypercarbia increased the anastomotic Qbr through a mechanism involving cyclooxygenase products of arachidonic acid.

Factors affecting bronchial blood flow through bronchopulmonary anastomoses in dogs

Most of the bronchial arterial blood flow (Qbr) drains through bronchopulmonary anastomoses into the pulmonary circulation, and the remainder goes into the systemic venous system via the bronchial veins. We studied the relationship between blood flow through bronchopulmonary anastomoses, and alveolar pressure and pulmonary vascular pressures as well as hydrostatic pressure in the bronchial veins in 10 adult dogs. The pulmonary artery and vein of the experimental left lower lobes (LLL) of open-chested, anesthetized dogs were isolated and connected to reservoirs. That part of the Qbr that flowed through bronchopulmonary anastomoses into the reservoirs was continuously measured at constant pulmonary vascular pressures of 0 cm H2O relative to the lung base. Any bronchial blood volume that retained within the LLL was estimated from changes in lobe weight. The lobe was distended with 5% CO2 and air, at alveolar pressures of 5, 10, or 20 cm H2O in a random sequence. Because bronchial veins drain into the azygos vein, the bronchial venous pressure was elevated by snaring the azygos vein. The mean anastomotic Qbr was 4.4 +/- 1.1 (mean +/- SEM) ml/min and it decreased by 23 and 39% when alveolar pressure was raised from 5 cm H2O to 10 and 20 cm H2O respectively (p less than 0.05). Approximately 75% of the total anastomotic Qbr was collected from the pulmonary venous reservoir at all alveolar pressures. When both pulmonary artery and venous pressures were increased higher than the alveolar pressure (zone III), azygos snaring increased the anastomotic Qbr by 13 and 31% at alveolar pressures of 10 and 20 cm H2O, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Nifedipine dilates the pulmonary vasculature without producing symptomatic systemic hypotension in upright resting and exercising patients with pulmonary hypertension secondary to chronic obstructive pulmonary disease

Vasodilator therapy may lower pulmonary vascular resistance in patients with chronic air-flow limitation. However, the effects of these agents on left ventricular afterload, cardiac output, and bronchial smooth muscle could lower the calculated pulmonary vascular resistance without specifically affecting pulmonary vascular tone. In addition, systemic hypotension in the upright position and worsening ventilation/perfusion heterogeneity could limit their use. We determined the pulmonary driving pressure (pulmonary arterial-pulmonary arterial wedge pressure) to flow relationship, as well as the transmural pulmonary arterial pressure in 9 patients with severe chronic air-flow limitation with pulmonary hypertension while in a clinically stable condition. Measurements were made at rest and during 3 stages of progressively increasing upright exercise on a bicycle before and after a single 20-mg dose of nifedipine. Nifedipine displaced both the driving pressure to flow and the pulmonary arterial transmural pressure to flow relationships towards higher flows in every subject, suggesting an active vasodilation. In the upright position, PaO2 did not change, and the systemic arterial pressure was only mildly reduced. In patients with pulmonary hypertension from chronic air-flow limitation, acute administration of nifedipine to upright patients causes pulmonary, as well as systemic vasodilation without causing symptomatic hypotension or reducing arterial oxygenation.

Effects of accidental chlorine inhalation on pulmonary function

In an industrial accident, 19 previously healthy workers were briefly exposed to high concentrations of chlorine gas. Pulmonary function tests were done at intervals for about two years but complete follow-up data were available in only 11 subjects. Immediately following the exposure, airway obstruction was detected in 10 of 19 patients; 700 days later this was found in only 3 of 11 patients. Two of these three patients had a history of smoking, however. The mean residual volume was 141% +/- 97 (mean +/- standard error of the mean) on day 1. In subsequent follow-up studies, the residual volume progressively fell in all patients, and 700 days later the mean residual volume was 90% +/- 5. In 5 of the 19 subjects, all pulmonary function test results were within normal limits on day 1. Apparently in some subjects acute exposure to chlorine gas may cause immediate changes in the lung functions, but these changes gradually resolve. Because of the small number of patients in our series, however, the long-term effects of chlorine are less apparent.

Efficiency of air compressor-driven nebulizers

Five different volumes of test solutions (1 to 3 ml) containing 15 mg of metaproterenol were placed in each of five different nebulizers. The time to complete nebulization and the amount of drug delivered varied considerably, depending upon the initial volume of solution placed in the nebulizer. Small volumes (1 ml) were almost totally retained in the nebulizer, whereas larger volumes (3 ml) took an unacceptably long time for nebulization. With vigorous agitation, a maximum of 53 to 72 percent of the dose left the nebulizer, but even less (34 to 59 percent) was delivered under simulated clinical conditions. When nebulization was synchronized with breathing, only 0.33 to 0.54 ml of solution (2 to 3.2 mg of metaproterenol) was delivered with 90 deep inhalations. If nebulization was continuous instead of intermittent during the time to take 90 breaths, the majority of the drug was nebulized to the atmosphere.

Acute increase in anastomotic bronchial blood flow after pulmonary arterial obstruction

We examined the acute changes in anastomotic bronchial blood flow (Qbr) serially for the 1st h after pulmonary arterial obstruction and subsequent reperfusion. We isolated and perfused the pulmonary circulation of the otherwise intact left lower lobe (LLL) with autologous blood in the widely opened chest of anesthetized dogs. Qbr was measured from the amount of blood overflowing from the closed pulmonary vascular circuit and the changes in the lobe weight. The right lung and the test lobe (LLL) were ventilated independently. The LLL, which was in zone 2 (mean pulmonary arterial pressure = 14.8 cm H2O, pulmonary venous pressure = 0, alveolar pressure = 5-15 cmH2O), was weighed continuously. The systemic blood pressure, gases, and acid-base status were kept constant. In control dogs without pulmonary arterial obstruction, the Qbr did not change for 2 h. Five minutes after pulmonary arterial obstruction, there was already a marked increase in Qbr, which then continued to increase for 1 h. After reperfusion, Qbr decreased. The increase in Qbr was greater after complete lobar than sublobar pulmonary arterial obstruction. It was unaltered when the downstream pulmonary venous pressure was increased to match the preobstruction pulmonary microvascular pressure. Thus, in zone 2, reduction in downstream pressure was not responsible for the increase in Qbr; neither was the decrease in alveolar PCO2, since ventilating the lobe with 10% CO2 instead of air did not change the Qbr. These findings suggest that there is an acute increase in Qbr after pulmonary arterial obstruction and that is not due to downstream pressure or local PCO2 changes.

Extra-alveolar vessel contribution to hydrostatic pulmonary edema in in situ dog lungs

We determined the relative contribution of larger extra-alveolar arteries and veins to hydrostatic edema in in situ dog lungs. Left lower lobe alveolar and vascular pressures were controlled in 24 open-chest, anesthetized, heparinized dogs. Zero pressure was at the lobe base. Normal blood gases were maintained by ventilating the right lung. The left lower lobe was inflated with 5% CO2 and air to an alveolar pressure of 10 or 25 cmH2O and suspended from a strain gauge, which allowed continual weight recording. Vascular pressures were raised to alveolar pressure plus lung height (zone III) before and after pulmonary arterial or venous embolization with 37- to 74-microns polystyrene beads, which isolated the larger extra-alveolar arteries or veins from alveolar vessels. The weight change occurring during the last 3 min of the 5-min hydrostatic stress was taken to represent transvascular fluid flux. At an alveolar pressure of 25 cmH2O (estimated transmural pressure 40 cmH2O), leakage from the larger extra-alveolar arteries and veins accounted for 41 and 32%, respectively, of the total transvascular fluid flux occurring after embolization. At an alveolar pressure of 10 cmH2O (estimated transmural pressure 22 cmH2O), no extra-alveolar vessel leakage occurred. However, when vascular pressures were raised to provide a transmural pressure similar to that present at the higher alveolar pressure, the same contribution from larger extra-alveolar vessels was observed.

Factorial rating system for comparative efficacy of antiasthmatic medication: a multicentric study report

Faced with 1-year daily medication diaries from over 300 patients, each documenting the use of from one to five medications a day, we found it was necessary to devise a system which would reduce this data into a form which would allow a meaningful interpretation of changes of medications in a single patient or group of patients. Since the medications were principally steroids, beta agonists, or xanthines, representative agents were chosen as the standard for each class and the other medications were rated against them. A conversion factor was then determined to allow comparison between classes. Each medication taken by a patient could now be expressed as a single number and the sum of all the medications would be the individual's Asthma Medication Index. The AMI allowed (i) evaluation of a single patient over time, (ii) comparison of different patients at any single point or over a period of time, and (iii) evaluation of entire groups of patients over time as was the case in our evaluation of Zaditen. Application of the system allowed the differentiation of two therapeutic agents versus placebo during a 1-year study, revealing excellent correlation with the physician's global assessment of the patient's improvement. With proper modification of the basic drug groups and intergroup factor relationship, the Index can be adapted to any disease state where a change in concomitant medication is an indicator of therapeutic effect.

Venous air embolism

Venous air embolism causes injury primarily by obstruction of blood flow from the right side of the heart to the left. This is due to mechanical obstruction of the right ventricular pulmonary outflow tract and pulmonary vasculature and to poorly understood pulmonary vasoconstrictive mechanisms. Venous air embolism can result in considerable hypoxemia from ventilation-perfusion maldistribution and shunt. With large emboli, systemic hypotension, myocardial ischemia, and arrhythmias can occur and result in death. One should be familiar with the clinical setting where embolism occurs, as prevention is the best treatment. When air embolism is suspected, placement of the patient in the left lateral decubitus position, initiating closed chest massage or, if possible, aspiration of air through a right atrial or Swan-Ganz catheter are all acceptable forms of treatment. The patient should also be given 100% oxygen.

Inhaled atropine sulfate: dose-response characteristics in adult patients with chronic airflow obstruction

Dose-response characteristics of inhaled atropine sulfate were examined in ten patients with chronic airflow obstruction using spirometric and plethysmographic measurements. Inhaled atropine in doses of 0.005, 0.01, 0.25, and 0.05 mg2kg of body weight and placebo were delivered by means of a precision metering device. All pulmonary function tests (FEV1, V50, and SGaw) improved progressively with increasing dose. There was a high degree of linear correlation between the peak response of each test and the logarithm of dose (r greater than or equal to 0.98). The highest dose studied (0.05 mg/kg) was found to have marginal benefit over 0.025 mg/kg, and had the highest incidence of adverse reactions. Duration of effect was dependent on dose. These results suggest that for adult patients with chronic airflow obstruction, 0.025 mg/kg delivered by a dosimeter approximates the optimally effective dose of inhaled atropine sulfate that can be given without unacceptable side effects.

Atropine and terbutaline aerosols in chronic bronchitis: efficacy and sites of action

To examine the additive properties and the sites of action of inhaled atropine sulfate (0.05 mg/kg of body weight) and terbutaline sulfate (0.005 mg/kg) in patients with chronic airflow obstruction, we tested these aerosols separately and together in a double-blind random sequence. Twelve patients with chronic bronchitis and perennial obstruction of airflow were studied by measuring three indices of efficacy (specific airway conductance [Gaw/VL], the forced expiratory volume in one second [FEV1] and the forced vital capacity [FVC]) and three indices of the site of action within the airway (delta [(Gaw/VL)/FEV1], the difference between the change in forced expiratory flow at 75 percent of vital capacity and the change in forced expiratory flow at 25 percent of vital capacity, and the change in density dependence of maximal airflow at 50 percent of vital capacity). Both atropine and the combination of atropine and terbutaline improved all indices of efficacy significantly more than did terbutaline. With individual exceptions, the addition of terbutaline to atropine improved Gaw/VL but not forced airflow. All measures of site of action suggested an advantage for atropine in relatively proximal airways. These results indicate that combined therapy with beta-adrenergic and anticholinergic bronchodilator drugs is marginally more effective than therapy with atropine alone in these patients and suggest that anticholinergic aerosols dilate larger airways more effectively than the beta-agonists.