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Forced vital capacity (FVC), a spirometric measure of pulmonary function, reflects lung volume and is used to diagnose and monitor lung diseases. We performed genome-wide association study meta-analysis of FVC in 52,253 individuals from 26 studies and followed up the top associations in 32,917 additional individuals of European ancestry. We found six new regions associated at genome-wide significance (P

Chronic obstructive pulmonary disease (COPD) is linked to cardiovascular disease; however, there are few studies on the associations of cardiovascular genes with COPD. We assessed the association of lung function with 2,100 genes selected for cardiovascular diseases among 20,077 European-Americans and 6,900 African-Americans. We performed replication of significant loci in the other racial group and an independent consortium of Europeans, tested the associations of significant loci with percent emphysema, and examined gene expression in an independent sample. We then tested the association of a related lipid biomarker with FEV1/FVC and percent emphysema. We identified one new polymorphism for FEV1/FVC (rs805301) in European-Americans (p=1.3×10−6) and a second (rs707974) in the combined European-American and African-American analysis (p=1.38×10−7). Both SNPs flank the gene for apolipoprotein M (apoM), a component of HDL. Both replicated in an independent cohort. SNPs in a second gene related to apoM and HDL, PCSK9 , were associated with FEV1/FVC among African-Americans. rs707974 was associated with percent emphysema among European-Americans and African-Americans, and APOM expression was related to FEV1/FVC and percent emphysema. Higher HDL levels were associated with lower FEV1/FVC and greater percent emphysema. These findings suggest a novel role for the APOM/HDL pathway in the pathogenesis of COPD and emphysema.

Background: Impaired lung function has been linked to obesity and systemic infl ammation. Pericardial fat has been shown to be associated with anomalies in cardiac structure, function, and atherosclerosis. We hypothesized that pericardial fat may have a similar role in the impairment of lung function. Methods: Cross-sectional associations of pericardial fat volumes, quantifi ed by multidetector CT scan, with FEV 1 and FVC assessed by spirometry, were investigated in 1,293 participants (54.5 10.8 years; 66.4% women) in the Jackson Heart Study. We also examined whether these associations were independent of visceral adipose tissue (VAT). Results: Pericardial fat was associated with impaired lung function after multivariable adjustment, but these associations generally did not remain after adjustment for VAT. An exception was the FEV 1 /FVC ratio. Higher pericardial fat volumes were associated with higher odds of a restrictive lung pattern and lower odds of airway obstruction. Participants in the highest quartile had the highest odds of a restrictive lung pattern (OR, 1.85; 95% CI, 1.22-2.79, compared with quartile 1), even after adjustment for VAT. The odds of obstruction decreased across increasing quartiles of pericardial fat. These relationships were generally graded, suggesting dose-response trends. Conclusions: Pericardial fat is generally associated with lower lung function and independently associated with a restrictive lung pattern in middle-aged and elderly adults. Further research is needed to fully understand the mechanisms through which pericardial fat contributes to pulmonary anomalies.

Purpose: Impaired pulmonary function has been associated with increased cardiovascular disease incidence and mortality. The objective of this study was to investigate associations between pulmonary function and left ventricular (LV) mass. Methods: Participants were African American women (n = 1,069) and men (n = 555) aged 49–73 years, from the Atherosclerosis Risk in Communities study. Mean pulmonary function values at the first (1987–1989) and second (1990–1992) examinations were used. Echocardiograms were performed at the third and early in the fourth examinations (1993–1996). Analysis of covariance and linear regression were used to assess associations. Results: Mean levels of LV mass decreased with increasing quintiles of forced expiratory volume in one second (FEV1) among female never smokers (P = 0.039). Forced vital capacity (FVC) showed stronger associations than FEV1 with LV mass. Among men, LV mass was positively associated with FEV1 among current and never smokers, and with FVC among never smokers. Additional analyses among never smokers revealed significant inverse associations between LV mass and FVC among women with waist-to-hip ratios of >0.85 and those with no history of diabetes. In contrast, significant positive associations between LV mass and FVC were seen among male never smokers with body mass index (BMI) of ≤24.9 kg/m2, waist-to-hip ratios of ≤0.95, no history of hypertension or diabetes, and ≤60 years old. BMI and waist-to-hip ratio significantly modified associations among men. Conclusions: Among never smokers, LV mass and pulmonary function were inversely associated among women and positively associated among men. Further studies are warranted. (Echocardiography 2012;29:131-139)

Background Pleural tuberculosis (TB) should be considered in any patient with a lymphocytic pleural effusion. The diagnostic approach is under debate. Knowledge of pleural TB epidemiology would be beneficial. To help clarify pleural TB epidemiology, we analyzed US national TB surveillance data for 1993 to 2003. Methods We compared pleural TB to pulmonary TB (where each was reported as the major site of TB disease, and no additional sites of disease were reported). Applicable statistical tests were performed; p Results From 1993 through 2003, 7,549 cases of pleural TB and 156,779 cases of pulmonary TB were reported (in 2003: pleural TB, 536 cases; pulmonary TB, 10,551 cases). The annual proportion of pleural TB was relatively stable (median rate, 3.6%; range, 3.3 to 4.0%) compared to that for pulmonary TB, which steadily decreased (average annual decrease, 0.9%; p Conclusions Knowledge of pleural TB demographic, clinical, and drug-resistance patterns may assist clinicians in making diagnostic and therapeutic decisions.

Asthma originates from genetic and environmental factors with about half the risk of disease attributable to heritable causes. Genome-wide association studies, mostly in populations of European ancestry, have identified numerous asthma-associated single nucleotide polymorphisms (SNPs). Studies in populations with diverse ancestries allow both for identification of robust associations that replicate across ethnic groups and for improved resolution of associated loci due to different patterns of linkage disequilibrium between ethnic groups. Here we report on an analysis of 745 African-American subjects with asthma and 3,238 African-American control subjects from the Candidate Gene Association Resource (CARe) Consortium, including analysis of SNPs imputed using 1,000 Genomes reference panels and adjustment for local ancestry. We show strong evidence that variation near RAD50/IL13, implicated in studies of European ancestry individuals, replicates in individuals largely of African ancestry. Fine mapping in African ancestry populations also refined the variants of interest for this association. We also provide strong or nominal evidence of replication at loci near ORMDL3/GSDMB, IL1RL1/IL18R1, and 10p14, all previously associated with asthma in European or Japanese populations, but not at the PYHIN1 locus previously reported in studies of African-American samples. These results improve the understanding of asthma genetics and further demonstrate the utility of genetic studies in populations other than those of largely European ancestry.

Context: Endothelial function is abnormal in chronic obstructive pulmonary disease (COPD); whether endothelial dysfunction causes COPD is unknown.Objective: Test associations of endothelial biomarkers with FEV1 using instrumental variables.Methods: Among 26 907 participants with spirometry, ICAM-1, P-selectin, E-selectin and endothelin-1 were measured in subsets.Results: ICAM-1 and P-selectin were inversely associated with FEV1 among European-Americans (−29 mL and −34 mL per standard deviation of log-transformed biomarker, p

Increased intracellular calcium concentration ([Ca(2+)](i)) is required for smooth muscle contraction. In tracheal and other tonic smooth muscles, contraction and elevated [Ca(2+)](i) are maintained as long as an agonist is present. To evaluate the physiological role of steady-state increases in Ca(2+) on tension maintenance, [Ca(2+)](i) was elevated using ionomycin, a Ca(2+) ionophore or charybdotoxin, a large-conductance calcium-activated potassium channel (K(Ca)) blocker prior to or during exposure of tracheal smooth muscle strips to ACh (10(-9) to 10(-4) M). Ionomycin (5mgr;M) in resting muscles induced increases in [Ca(2+)](i) to 500 +/- 230 nM and small increases in force of 2.6 +/- 2.3 N/cm(2). This tension is only 10% of the maximal tension induced by ACh. Charybdotoxin had no effect on [Ca(2+)](i) or tension in resting muscle. After pretreatment of muscle with ionomycin, the concentration-response relationship for ACh-induced changes in tension shifted to the left (EC(50) = 0.07 +/- 0.05mgr;M ionomycin; 0.17 +/- 0.07mgr;M, control, p0.05). When applied to the muscles during steady-state responses to submaximal concentrations of ACh, both ionomycin and charybdotoxin induced further increases in tension. The same magnitude increase in tension occurs after ionomycin and charybdotoxin treatment, even though the increase in [Ca(2+)](i) induced by charybdotoxin is much smaller than that induced by ionomycin. We conclude that the resting muscle is much less sensitive to elevation of [Ca(2+)](i) when compared to muscles stimulated with ACh. Steady-state [Ca(2+)](i) limits tension development induced by submaximal concentrations of ACh. The activity of K(Ca) moderates the response of the muscle to ACh at concentrations less than 1mgr;M. Copyright 1996 S. Karger AG, Basel

The roles of Ca(2+) mobilization in development of tension induced by acetylcholine (ACh, 0.1-100mgr;M) in swine tracheal smooth muscle strips were studied. Under control conditions, ACh induced a transient increase in free cytosolic calcium concentration ([Ca(2+)](i)) that declined to a steady-state level. The peak increase in [Ca(2+)](i) correlated with the magnitude of tension at each [ACh] after a single exposure to ACh, while the steady-state [Ca(2+)](i) did not. Removal of extracellular Ca(2+) had little effect on peak [Ca(2+)](i) but greatly reduced steady-state increases in [Ca(2+)](i) and tension. Verapamil inhibited steady-state [Ca(2+)](i) only at [ACh]1mgr;M. After depletion of internal Ca(2+) stores by 10 min exposure to ACh in Ca(2+)-free solution and then washout of ACh for 5 min in Ca(2+)-free solution, simultaneous re-exposure to ACh in the presence of 2.5 mM Ca(2+) increased [Ca(2+)](i) to the control steady-state level without overshoot. The tension attained was the same as control for each [ACh] used. Continuous exposure to successively increasing [ACh] (0.1-100mgr;M) also reduced the overshoot of [Ca(2+)](i) at 10 and 100mgr;M ACh, yet tension reached control levels at each [ACh] used. We conclude that the steady-state increase in [Ca(2+)](i) is necessary for tension maintenance and is dependent on Ca(2+) influx through voltage-gated calcium channels at 0.1mgr;M ACh and through a verapamil-intensitive pathway at 10 and 100mgr;M. The initial transient increase in calcium arises from intracellular stores and is correlated with the magnitude of tension only in muscles that have completely recovered from previous exposure to agonists. Copyright 2001 S. Karger AG, Basel

To study platelet cell calcium in dogs, we measured the fura-2-determined calcium concentration (Cai) in platelets derived from blood drawn through indwelling arterial catheters in four dogs. Platelet samples were obtained 3 days a week for 39 days. Canine platelet Cai averages 40.5 +/- 1.7 nmol/L when corrected for extracellular fura-2 dye (n = 46); this mean is significantly smaller than the value obtained without such a correction (50.2 +/- 2.0 nmol/L, P < .05). The amplitude of thrombin-induced Ca2+ transients is proportional to basal Cai, increasing 4.9 +/- 0.9 nmol/L peak Ca2+ per nmol/L increase in baseline Ca2+.

Impaired pulmonary function has been associated with increased cardiovascular disease incidence and mortality. The objective of this study was to investigate associations between pulmonary function and left ventricular (LV) mass.Participants were African American women (n = 1,069) and men (n = 555) aged 49-73 years, from the Atherosclerosis Risk in Communities study. Mean pulmonary function values at the first (1987-1989) and second (1990-1992) examinations were used. Echocardiograms were performed at the third and early in the fourth examinations (1993-1996). Analysis of covariance and linear regression were used to assess associations.Mean levels of LV mass decreased with increasing quintiles of forced expiratory volume in one second (FEV(1) ) among female never smokers (P = 0.039). Forced vital capacity (FVC) showed stronger associations than FEV(1) with LV mass. Among men, LV mass was positively associated with FEV(1) among current and never smokers, and with FVC among never smokers. Additional analyses among never smokers revealed significant inverse associations between LV mass and FVC among women with waist-to-hip ratios of0.85 and those with no history of diabetes. In contrast, significant positive associations between LV mass and FVC were seen among male never smokers with body mass index (BMI) of ≤24.9 kg/m(2) , waist-to-hip ratios of ≤0.95, no history of hypertension or diabetes, and ≤60 years old. BMI and waist-to-hip ratio significantly modified associations among men.Among never smokers, LV mass and pulmonary function were inversely associated among women and positively associated among men. Further studies are warranted.

Impaired lung function has been linked to obesity and systemic inflammation. Pericardial fat has been shown to be associated with anomalies in cardiac structure, function, and atherosclerosis. We hypothesized that pericardial fat may have a similar role in the impairment of lung function.Cross-sectional associations of pericardial fat volumes, quantified by multidetector CT scan, with FEV(1) and FVC assessed by spirometry, were investigated in 1,293 participants (54.5 ± 10.8 years; 66.4% women) in the Jackson Heart Study. We also examined whether these associations were independent of visceral adipose tissue (VAT).Pericardial fat was associated with impaired lung function after multivariable adjustment, but these associations generally did not remain after adjustment for VAT. An exception was the FEV(1)/FVC ratio. Higher pericardial fat volumes were associated with higher odds of a restrictive lung pattern and lower odds of airway obstruction. Participants in the highest quartile had the highest odds of a restrictive lung pattern (OR, 1.85; 95% CI, 1.22-2.79, compared with quartile 1), even after adjustment for VAT. The odds of obstruction decreased across increasing quartiles of pericardial fat. These relationships were generally graded, suggesting dose-response trends.Pericardial fat is generally associated with lower lung function and independently associated with a restrictive lung pattern in middle-aged and elderly adults. Further research is needed to fully understand the mechanisms through which pericardial fat contributes to pulmonary anomalies.

Leptin, a 16-kDa protein, has proinflammatory properties and has been linked to respiratory physiological responses in majority white populations. Little is known, however, about the relationship of leptin with lung function in nonwhites. Cross-sectional associations of circulating serum leptin concentrations with forced expiratory volume in 1 s (FEV(1)), FEV in 6 s (FEV(6)), and vital capacity (FVC), assessed by spirometry, were examined in 4,679 African-American men and women participants (54.3 ± 12.4 years; 62.7% women) in the Jackson Heart Study (JHS). The independent association of leptin was examined in relation to FEV(1), FEV(6), and FVC% predicted after adjustment for age, education, smoking status, pack-years of cigarette smoking, respiratory medication use, and menopausal status in women; additional adjustment included total body weight, waist circumference, and BMI. Serum leptin was inversely related to FEV(1), FEV(6), and FVC% predicted values in men. A dose-response relationship was observed with men in the highest leptin quartile having a significantly lower lung function compared to men in the lower leptin quartile. BMI significantly modified this relationship in women: leptin was most consistently associated with lung function in obese women, less consistent in overweight women, and absent in normal-weight women. Serum leptin concentration was strongly, inversely, and independently associated with lung function in African Americans, especially African-American men and obese women.

The aims of this study were to investigate the baseline prevalence of and risk factors associated with asthma, classify asthma severity, and describe medication use in a population-based sample of African American men and women 21 to 84 years of age from the Jackson Heart Study (JHS). Participants provided responses to respiratory and medical history questions and a medication inventory and underwent spirometry and other clinical examinations. These data were used to examine the extent to which novel and traditional risk factors were associated with asthma. Of the 4,098 participants included in this analysis, 9.4% reported lifetime asthma (5.7% current, 3.7% former), and current asthma was higher in women (6.8%) than in men (3.8%). An additional 9.8% reported an attack of wheeze with shortness of breath or non-doctor confirmed asthma (i.e., "probable" asthma). The mean forced expiratory volume in 1 second (FEV(1))% predicted was lower in those reporting current asthma (women: 83.7 +/- 18.0; men: 75.2 +/- 16.8) compared to those not reporting asthma (women: 95.6 +/- 16.7; men: 91.7 +/- 16.0). Current and probable asthma was associated with lower serum cortisol levels and hypertension medication use, along with traditional risk factors (i.e., lower socio-economic status, higher global stress scores, obesity, and fair to poor perceived general health). Severe asthma was low among participants reporting current (9.8%), former (3.3%), and probable (4.9%) asthma. Asthma medication use was reported by nearly 60% of the participants reporting current asthma. Asthma in African American adults is associated with decreased serum cortisol, hypertension medication use, and considerable lung function impairment compared to those who did not report asthma. The prevalence of asthma in the JHS is lower than state and national estimates, although the estimates are not directly comparable. Furthermore, asthma is drastically underdiagnosed in this population.

Background Smoking is the single most important risk factor for COPD, yet there is still disagreement about the differences in the effect of smoking between white and African-American people. We hypothesized that the results of spirometry between smokers of the two races are equivalent if reference equations and lower limits of normal appropriate for each race are used. Methods We retrospectively analyzed all spirometry results in smokers over a 1-year period from the G.V. (Sonny) Montgomery VA Medical Center and excluded those that did not meet American Thoracic Society standards, or those from patients with additional medical problems. The remaining patients were classified by race and then matched for age and smoking history; 108 patients in each group were included, which met the power analysis goal of 98. The two groups were similar in age (57.5 years vs 57.0 years), smoking history (46.1 pack-years vs 46.0 pack-years), and body mass index (27.0 kg/m2 vs 28.3 kg/m2) for African Americans and whites, respectively. Data were analyzed using the unpaired t test, and p values were adjusted for multiple comparisons using the Bonferroni factor. Results There were statistically significant differences between African American and white smokers in FVC (3.67 ± 0.07 L vs 4.26 ± 0.08 L, p = 0.001) and FEV1 (2.33 ± 0.07 L vs 2.72 ± 0.08 L, p = 0.002), as expected from the normal populations; however, there were no differences in FVC as percentage of predicted (89.1 ± 1.3% vs 86.7 ± 1.5%, p = 0.71) and FEV1 as percentage of predicted (71.9 ± 2.1% vs 72.2 ± 1.8%, p = 1.00) when the reference equations appropriate for race were used (third National Health and Nutrition Examination Survey). There were also no differences between the number of subject with abnormal FEV1/FVC results (56 African Americans vs 58 whites, p = 1.00) when the appropriate lower limits of normal were used. Conclusions There are no differences in spirometry findings between African Americans and whites when abnormality is defined appropriately using reference equations and lower limits of normal for each race. By using either percentage cutoffs for abnormality, or by adjusting for African-American equations only appropriate for whites, we were able to mimic with our data conflicting results in the literature.

purpose: Acute respiratory failure necessitating intubation and mechanical ventilation in patients with acute severer asthma is relatively uncommon, and there are few data available regarding positive pressure ventilation in critically ill patients with asthma. We therefore decided to evaluate our experience with the use of mechanical ventilation for acute asthma and to critically review previous reports on this subject. patietns and methods: A retrospective analysis of all medical records of patients who required mechanical ventilation for acute severe asthma was performed for the period of 1980 to 1988. Various clinical parameters were reviewed and examined via Fisher's exact test for association with survival. results: Twenty-seven patients who underwent ventilation for a total of 32 episodes of mechanical ventilation comprised our study group. The overall mortality was 22%. A total of 76 complications were documented, including six episodes of baro-trauma. The mean duration of artificial ventilation was 114 hours for nonsurvivors and 77 hours for survivors (p conclusion: Although there appears to be a trend toward increased survival after mechanical ventilation for acute asthma, ventilation of critically ill asthmatic patients continues to be a potentially perilous ventures associated with significant morbidity and mortality.

Train-of-four (TOF) monitoring is often recommended during the continuous use of neuromuscular blockade (NMB) [paralysis] in the ICU. Prior study results are conflicting regarding the benefits of TOF monitoring.Thirty patients in the medical ICU were randomized to TOF monitoring (n = 16) or to clinical assessment (n = 14) during continuous cisatracurium infusion. TOF monitoring was done at least every 4 h, with the goal being maintenance of one to two twitches. Statistical analysis was performed by two-tailed, unpaired t test (with Bonferroni correction for multiple comparisons), chi(2), and Fisher exact test, with p0.05 considered significant. Given a power of 80%, and the variance seen in the two groups, we estimate that the sample size used is sufficient to detect a change ofor = 60 min between groups for recovery time.The mean recovery time after cessation of paralytics was no different between TOF and clinical assessment (45 +/- 7 min vs 38 +/- 10 min, respectively [mean +/- SEM]). No differences were noted for mean APACHE (acute physiology and chronic health evaluation) II entry scores, glomerular filtration rates, or use of corticosteroids. No significant differences were noted between TOF monitoring and clinical assessment in mean total paralysis time (4,118 +/- 1,012 min vs 3,188 +/- 705 min, respectively), mean total cisatracurium dose (920 +/- 325 mg vs 715 +/- 167 mg), or dosage (2.3 +/- 0.2 microg/kg/min vs 2.9 +/- 0.2 microg/kg/min).TOF monitoring does not lead to improved recovery time or lower cisatracurium dosing compared with monitoring by clinical assessment. We conclude that TOF monitoring is unnecessary, and careful titration of the neuromuscular blocking agent by clinical assessment alone is sufficient in patients undergoing continuous cisatracurium NMB.

Purpose Flow rates and pressures generated by commercially available pleural drainage units (PDUs) and flow rates through available pleural drainage catheters (PDCs) are not known. This information may be important clinically depending on the volume of air leak associated with a bronchopleural fistula. Design Eight PDUs were assessed for flow rates at various suction levels and for the percent accuracy of suction pressures generated at various settings. Eleven commonly used PDCs were assessed for flow rates at various suction control levels. All devices were donated by their manufacturer. Flow rates and pressures were measured by a RT 200 Calibration Analyzer (Timeter Instrument Corporation; St. Louis, MO) at body temperature, ambient pressure, saturated with water vapor. Five devices of each type were tested. Analysis of variance was performed with p Results Multiple significant differences between PDUs were noted at a pressure of − 20 cm H 2 O. The Argyle Sentinel Seal (Sherwood Medical; Tillamore, Ireland) had significantly lower flow rates (mean ± SD, 10.8 ± 0.6 L/min) compared with all other models. The Argyle Aqua-Seal (Sherwood Medical) had the highest PDU flow rate of devices tested (42.1 ± 1.0 L/min). The accuracy of PDUs at manufacturer-suggested settings varied from a mean percentage error of 0.0 to 15.5% from expected pressures; significant differences were noted in accuracy among multiple interdevice pressure comparisons. Similarly, multiple significant flow rate differences between PDCs were noted at − 20 cm H 2 O. Lowest flow rates were noted with thoracentesis catheters (used as PDCs) containing side ports. Arrow drainage catheters (14F, pigtail and straight) [Arrow International; Reading, PA] both had significantly greater flow rates (both, 16.8 ± 0.1 L/min), compared with the 14F (12.8 ± 0.3) and 16F (14.8 ± 0.6) Cook devices (Cook; Bloomington, IN). Conclusions These differences in flow rates for PDUs and PDCs may be clinically important, particularly in patients with large pneumothorax-related air leaks. Observed differences in PDU-generated pressures are likely not clinically important.

Our objective was to compare respiratory muscle performance, pulmonary mechanics, and gas exchange between the BiPAP S/T-D ventilation system (Respironics Inc; Murrysville, PA) and the Servo Ventilator 900C (Siemens-Elma AB; Sweden) with similar inspiratory and expiratory airway pressure in patients who are recovering from acute respiratory failure.A prospective, randomized, clinical trial.Medical ICU.We studied 27 medical patients on mechanical ventilators following gradual pressure support weaning. Each patient breathed while in the following equivalent modes: (a) an inspiratory pressure preset (pressure support mode) of 5 cm H2O with an external positive end-expiratory pressure (PEEP) of 5 cm H2O on the Servo Ventilator 900C and (b) an inspiratory pressure preset of 10 cm H2O with an expiratory pressure preset of 5 cm H2O on the BiPAP S/T-D. Using the CP-100 pulmonary monitor, we compared the total work of breathing (WOB), the pressure-time index (PTP), and other pulmonary mechanics and gas exchange parameters between the two modes.The WOB injoules per liter (mean +/- SE) (0.76+/-0.08 vs 0.73+/-0.08, p = 0.70), the WOB in joules per minute (8.62+/-1.06 vs 8.11+/-0.96, p = 0.60), and the PTP in cm H2O/s/min (187+/-18 vs 167+/-18, p = 0.21) between the BiPAP S/T-D and the Servo Ventilator 900C were not statistically different. There were statistically significant differences between the two ventilators in auto-PEEP (1.34+/-0.37 vs 0.88+/-0.30 cm H2O, p = 0.03), duty cycle (0.44+/-0.01 vs 0.37+/-0.01, p0.001), and expiratory airway resistance (11.81+/-1.53 vs 8.75+/-1.22 cm H2O/L/s, p0.001), but not in respiratory rate (27.48+/-1.54 vs 28.06+/-1.61 breaths/min, p = 0.40) or in minute ventilation (10.43+/-0.59 vs 10.27+/-0.37 L/min, p = 0.66). There was a statistically significant difference in the ratio of Pa(O2) to the fraction of inspired oxygen (F(IO2)) (333+/-21 vs 300+/-22, p0.03) but not in Pa(CO2) (48+/-2 vs 47+/-2 mm Hg, p = 0.59) between the BiPAP S/T-D and the Servo Ventilator 900C.Despite differences in initiating and maintaining the inspiratory and expiratory phases, in breathing circuits, and in ventilator circuits between the two ventilators, the performance of the BiPAP S/T-D is equally efficacious to that of a conventional mechanical ventilator in supporting respiratory muscles. Thus, the BiPAP S/T-D is safe and effective when used in mechanically ventilated patients recovering from acute respiratory failure who do not require total ventilatory support.

In this paper we describe communications between a personal computer and any instrument with a serial port for the purpose of collecting data or controlling equipment and a program for performing this task. From a user-defined file, the software reads the communication parameters: baud rate, data bits, stop bits and parity. The communication protocol is also read: echo, acknowledge and end-of-transmission characters. The software can be used to determine the protocol, to check the integrity of the communications, and can form the basis of a program for more specific applications.

Comprehensive description of irritable bowel syndrome by subtypes in African-Americans versus Caucasians

To determine if alveolar hypoxia causes subclinical noncardiogenic pulmonary edema, we measured in 8 dogs the rebreathing pulmonary tissue volume (Vt) and the pulmonary extravascular water volume using the single-pass double-indicator dilution method. After baseline measurements, the dogs were ventilated with the lowest concentration of oxygen that would not cause left ventricular failure (9 to 13% O2). One to 6 h of hypoxia had no effect on Vt, but caused a reversible 38% fall in pulmonary extravascular lung water volume by the indicator method (p less than 0.01). The ratio of the extravascular to vascular volumes estimated from the relative peak heights of the 2 indicator dilution curves did not change with hypoxia, which implies that hypoxia caused a derecruitment of pulmonary blood vessels rather than a real decrease in extra-vascular lung water volume. This conclusion is supported by our rebreathing measurement of the airway exchangeable tissue volume, which is virtually independent of tissue perfusion, and which did not fall during hypoxia. To determine if this alteration in the pulmonary circulation can cause pulmonary edema when the cardiac output is increased, we opened a femoral artery to femoral vein shunt in 9 additional dogs during ventilation with 9 to 13% oxygen. Cardiac output increased over 50% but pulmonary edema developed in only 1 dog, the dog that also had the highest mean pulmonary artery pressure of the group (35 mmHg versus group mean of 26 mmHg during hypoxia). We conclude that 1 to 6 h of alveolar hypoxia in dogs consistently decreases the volume of perfused lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

A program to perform a nonlinear best fit for separable and nonseparable equations is described. This software is written in Turbo-Pascal so that it can be run both on CP/M systems or PC-DOS systems; in the latter, graphics can be performed using the Turbo Graphix Toolbox. From initial estimates the regression coefficients as well as the statistics are calculated. Two examples are shown: one of a separable equation describing receptor binding; the second of a nonseparable equation, describing the displacement of labeled agonist by an inhibitor. The only difference in the fit between a separable and a nonseparable equation is that the latter requires iterations for an estimate of the dependent variable every time that new regression coefficients are calculated.

Models can be used as teaching tools to study complex phenomena. This model uses simplifications of blood gas subroutines to provide fast execution of the effect of the distribution of ventilation and blood flow in the lung on arterial blood gases. Assumptions are made that introduce only small errors but that avoid the use of iterations which would slow down execution. The use of Turbo-Pascal as the programming language allows for not only speed in development and execution but also portability to a variety of computers including CP M systems and IBM-PCs.

We measured pulmonary tissue volume (Vt) and capillary blood flow\(\dot Q_c \) by rebreathing acetylene as the soluble gas in 94 male and 82 female patients with normal healthy lungs. We found that the standard deviation of Vt was a function of Vt and that the standard deviation of\(\dot Q_c \) was a function of\(\dot Q_c \) logarithm transforms were used to prevent this. A significant correlation exists between log Vt and body surface area (BSA) and log Vt and vital capacity (VC). For both sets of regressions older subjects (≥40 years of age) exhibited greater variability about the regression line than younger subjects; therefore the 2 age groups of subjects were analyzed separately for tissue volume. We describe regression equations of log Vt vs. BSA or VC for younger male, younger female, older male, and older female patients. The normal limits by sex and age groups are also included. A significant correlation was found between log\(\dot Q_c \), BSA, and age. Thus 2 equations, for male and female patients, are used to predict log\(\dot Q_c \) based on these 2 covariates.

The process of formal decision analysis is illustrated by using the case of the hepatitis B vaccine in a computer program designed to teach both subjects to medical students. The software presents the medical facts, determines personal risks, allows input of personal values and calculates utilities for the various branches of the decision tree. There are three possible choices: vaccinate; screen first for antibodies against the hepatitis B virus and vaccinate only if negative; and wait (do not vaccinate). The decision with the utility of the highest numerical value is assumed to be the best under the given set of circumstances. Unlike commercial packages, this software contains the information internally and does not require that the user be familiar with either medical decision analysis or with the medical aspects of hepatitis. The program is available for PC's.

Pulmonary Function Laboratories with manual equipment can expedite calculations and make them more accurate by using a programmable calculator that will compute functions and predictive equations. However, a custom-made set of programs is better than calculator libraries available from the manufacturer. With custom-made programs, calculations remain as the staff is used to receiving them, programs can be stored in the memory and called independently and only those tests used routinely need to be available.

Measurements of pulmonary tissue volume (Vt) and pulmonary capillary blood flow\(\dot Q\)c by noninvasive rebreathing techniques have been introduced during the last decade. Despite the good agreement between Vt and\(\dot Q\)c and other invasive methods to measure lung water and blood flow, few studies have taken advantage of rebreathing. One possible reason is that surprisingly little is known about the reproducibility of the technique in individuals during the course of time. We measured Vt and\(\dot Q\)c by rebreathing acetylene in 8 normal young non-smokers and found that both the parameters and their coefficients of variation did not change when the measurements were made in each person in three different ways: 1) consecutively, 2) daily during a period of up to 6 weeks, and 3) hourly during a 24 hour period. The coefficients of variation for Vt ranged from 6% to 17%, with an average of 9.7% and for\(\dot Q\)c from 5% to 17% with an average of 8.9%. In 8 older subjects, the variation was similar to younger subjects. Thus we believe that rebreathing can be used experimentally and clinically but measurements should be made in triplicate.