Differences In Lung Volume Research Articles

Long-term post-pneumonectomy pulmonary adaptation following all-trans-retinoic acid supplementation

In adult dogs following right pneumonectomy (PNX) and receiving all-trans-retinoic acid (RA) supplementation for 4 mo, we found modestly enhanced alveolar-capillary growth in the remaining lung without enhanced resting lung function (J Appl Physiol 96: 1080-1089 and 96: 1090-1096, 2004). Since alveolar remodeling progresses beyond this period and the lipid-soluble RA continues to be released from tissue stores, we hypothesized that RA supplementation may exert additional long-term effects. To examine this issue, adult male litter-matched foxhounds underwent right PNX followed by RA supplementation (2 mg/kg po 4 days/wk, n = 6) or placebo (n = 4) for 4 mo. Cardiopulmonary function was measured at rest and during exercise at 4 and 20 mo post-PNX. The remaining lung was fixed under a constant airway pressure for morphometric analysis. Comparing RA treatment to placebo controls, there were no differences in aerobic capacity, cardiopulmonary function, or lung volume at rest or exercise. Alveolar-capillary basal lamina thickness and mean harmonic thickness of air-blood diffusion barrier were 23-29% higher. The prevalence of double-capillary profiles remained 82% higher. Absolute volumes of septal interstitium, collagen fibers, cells, and matrix were 32% higher; the relative volumes of other septal components and alveolar-capillary surface areas expressed as ratios to control values were up to 24% higher. Thus RA supplementation following right PNX modestly and persistently enhanced long-term alveolar-capillary structural dimensions, especially the deposition of interstitial and connective tissue elements, in such a way that caused a net increase in barrier resistance to diffusion without improving lung mechanics or gas exchange.

Emphysema Quantification in Inflation-Fixed Lungs Using Low-Dose Computed Tomography and 3He Magnetic Resonance Imaging

To evaluate the use of inflation-fixed lung tissue for emphysema quantification with computed tomography (CT) and He magnetic resonance (MR) diffusion imaging. Fourteen subjects representing a range of chronic obstructive pulmonary disease severity who underwent complete or lobar lung resection were studied. Computed tomographic measurements of lung attenuation and MR measurements of the hyperpolarized 3He apparent diffusion coefficient (ADC) in resected specimens fixed in inflation with heated formalin vapor were compared with measurements obtained before fixation. The mean (SD) CT emphysema indices were 56% (17%) before and 58% (19%) after fixation (P = 0.77; R = 0.76). Index differences correlated with differences in lung volume (R = 0.47). The mean (SD) 3He ADCs were 0.40 (0.15) cm/s before and 0.39 (0.14) cm/s after fixation (P = 0.03, R = 0.98). The CT emphysema index and the 3He ADC were correlated before (R = 0.89) and after fixation (R = 0.79). Concordance of CT and 3He MR imaging measurements in unfixed and inflation-fixed lungs supports the use of inflation-fixed lungs for quantitative imaging studies in emphysema.

Lung volume and pharyngeal stability in sleeping humans: the knee bone is connected to the thigh bone

in 1988 the Journal of Applied Physiology published a seminal article by William Van de Graaff ([13][1]) demonstrating that inflation of the thorax in anesthetized dogs decreased upper airway resistance independently of upper airway muscle activity. The mechanism underlying this effect was shown to

Automatic 3-D Breath-Hold Related Motion Correction of Dynamic Multislice MRI

Magnetic resonance (MR) cine images are often used to clinically assess left ventricular cardiac function. In a typical study, multiple 2-D long axis (LA) and short axis (SA) cine images are acquired, each in a different breath-hold. Differences in lung volume during breath-hold and overall patient motion distort spatial alignment of the images thus complicating spatial integration of all image data in three dimensions. We present a fully automatic postprocessing approach to correct these slice misalignments. The approach is based on the constrained optimization of the intensity similarity of intersecting image lines after the automatic definition of a region of interest. It uses all views and all time frames simultaneously. Our method models both in-plane and out-of-plane translations and full 3-D rotations, can be applied retrospectively and does not require a cardiac wall segmentation. The method was validated on both healthy volunteer and patient data with simulated misalignments, as well as on clinical multibreath-hold patient data. For the simulated data, subpixel accuracy could be obtained using translational correction. The possibilities and limitations of rotational correction were investigated and discussed. For the clinical multibreath-hold patient data sets, the median discrepancy between manual SA and LA contours was reduced from 2.83 to 1.33 mm using the proposed correction method. We have also shown the usefulness of the correction method for functional analysis on clinical image data. The same clinical multibreath-hold data sets were resegmented after positional correction, taking newly available complementary information of intersecting slices into account, further reducing the median discrepancy to 0.43 mm. This is due to the integration of the 2-D slice information into 3-D space.

Speech breathing in speakers who use an electrolarynx

Speakers who use an electrolarynx following a total laryngectomy no longer require pulmonary support for speech. Subsequently, chest wall movements may be affected; however, chest wall movements in these speakers are not well defined. The purpose of this investigation was to evaluate speech breathing in speakers who use an electrolarynx during speech and reading tasks. Six speakers who use an electrolarynx underwent an evaluation of chest wall kinematics (e.g., chest wall movements, temporal characteristics of chest wall movement), lung volumes, temporal measures of speech, and the interaction of linguistic influences on ventilation. Results of the present study were compared to previous reports in speakers who use an electrolarynx, as well as to previous reports in typical speakers. There were no significant differences in lung volumes used and the general movement of the chest wall by task; however, there were differences of note in the temporal aspects of chest wall configuration when compared to previous reports in both typical speakers and speakers who use an electrolarynx. These differences were related to timing and posturing of the chest wall. The lack of differences in lung volumes and chest wall movements by task indicates that neither reading nor spontaneous speech exerts a greater influence on speech breathing; however, the temporal and posturing results suggest the possibility of a decoupling of the respiratory system from speech following a total laryngectomy and subsequent alaryngeal speech rehabilitation. Learning outcomes The reader will be able to understand and describe: (1) The primary differences in speech breathing across alaryngeal speech options; (2) how speech breathing specifically differs (i.e., lung volumes and chest wall movements) in speakers who use an electrolarynx; (3) How the coupling of speech and respiration is altered when pulmonary air is no longer used for speech.

Assessment of air space size characteristics by intercept (chord) measurement: an accurate and efficient stereological approach

The mean linear intercept (chord) length (L(m)) is a useful parameter of peripheral lung structure as it describes the mean free distance in the air spaces. It is often misinterpreted as a measure of "alveolar size," and its estimation is fraught with a number of pitfalls. We present two methods for the accurate estimation of L(m): 1) the indirect method, which derives L(m) from the volume-to-surface ratio of air spaces estimated by point counting methods, and 2) the direct method, which uses a set of random intercepts and calculates L(m) from their frequency distribution, for which we introduce a new and accurate method. Both methods are efficient and, with proper precautions, unbiased. The meaning of L(m) is assessed in two different examples. In a physiological study, the effect of different inflation levels is studied, showing that L(m) critically depends on lung inflation. In an experimental study on emphysema-like changes in a genetic mouse model, the effect of heterogeneity of air space size is assessed; these results are obtained partly because of differences in lung volume due to altered recoil in the emphysematous lungs. In conclusion, although L(m) is not a robust parameter of internal lung structure because it crucially depends on lung volume, it is still a valid measure for which accurate and efficient methods are available that yield additional parameters such as size distribution or alveolar surface area.

Effects of Obesity on Perceptual and Mechanical Responses to Bronchoconstriction in Asthma

The influence of obesity on the perception of respiratory discomfort during acute bronchoconstriction in asthma is unknown. We hypothesized that the respiratory impairment associated with an increased body mass index (BMI) would predispose to greater perceived symptom intensity during acute airway narrowing. We therefore compared relationships between induced changes in dyspnea intensity and lung function during methacholine (MCh) bronchoprovocation in obese (OBA) and normal-weight (NWA) individuals with asthma of mild to moderate severity. High-dose MCh challenge tests to a maximum 50% decrease in FEV(1) were conducted in 51 NWA (BMI, 18.5-24.9 kg/m(2); 29% male) and 45 OBA (BMI, 30.1-51.4 kg/m(2); 33% male) between 20 and 60 years of age. Serial spirometry, inspiratory capacity (IC), plethysmographic end-expiratory lung volume (EELV) and dyspnea intensity using the Borg scale were measured throughout bronchoprovocation. Spirometry and airway sensitivity were similar in both groups; baseline EELV was lower (P < 0.0005) and IC was higher (P = 0.007) in OBA compared with NWA. From baseline to PC(20), EELV increased more in OBA (20% predicted) than NWA (13% predicted) (P = 0.008) with concomitant greater reductions in IC (P < 0.0005). Dyspnea ratings were not different for a given FEV(1) or IC across groups. By mixed effects regression analysis, relationships between induced dyspnea and changes in lung function parameters were not influenced by BMI, sex, or their interaction. Perceptual responses to MCh-induced bronchoconstriction and lung hyperinflation were similar in obese and normal-weight individuals with asthma despite significant group differences in baseline lung volumes.

Assessment of lung development in isolated congenital diaphragmatic hernia using signal intensity ratios on fetal MR imaging

To investigate developmental changes in the apparently unaffected contralateral lung by using signal intensity ratios (SIR) and lung volumes (LV), and to search for correlation with clinical outcome. Twenty-five fetuses (22-37 weeks' gestation) were examined. Lung/liver signal intensity ratios (LLSIR) were assessed on T1-weighted and T2-weighted sequences for both lungs, then together with LV compared with age-matched controls of 91 fetuses by using the U test. Differences in LLSIRs and lung volumes were correlated with neonatal outcomes. LLSIRs in fetuses with congenital diaphragmatic hernia (CDH) were significantly higher in both lungs on T1-weighted images and significantly lower on T2-weighted images, compared with normals (p < 0.05), increasing on T2-weighted imaging and decreasing on T1-weighted imaging during gestation. Total LV were significantly smaller in the CDH group than in controls (p < 0.05). No significant differences in LLSIR of the two lungs were found. Outcomes correlated significantly with total LV, but not with LLSIR. Changes in LLSIR seem to reflect developmental impairment in CDH; however, they provide no additional information in predicting outcome. LV remains the best indicator on fetal MR imaging of neonatal survival in isolated, left-sided CDH.

Continued artificial selection for running endurance in rats is associated with improved lung function

Previous studies found that selection for endurance running in untrained rats produced distinct high (HCR) and low (LCR) capacity runners. Furthermore, despite weighing 14% less, 7th generation HCR rats achieved the same absolute maximal oxygen consumption (Vo(2max)) as LCR due to muscle adaptations that improved oxygen extraction and use. However, there were no differences in cardiopulmonary function after seven generations of selection. If selection for increased endurance capacity continued, we hypothesized that due to the serial nature of oxygen delivery enhanced cardiopulmonary function would be required. In the present study, generation 15 rats selected for high and low endurance running capacity showed differences in pulmonary function. HCR, now 25% lighter than LCR, reached a 12% higher absolute Vo(2max) than LCR, P < 0.05 (49% higher Vo(2max)/kg). Despite the 25% difference in body size, both lung volume (at 20 cmH(2)O airway pressure) and exercise diffusing capacity were similar in HCR and LCR. Lung volume of LCR lay on published mammalian allometrical relationships while that of HCR lay above that line. Alveolar ventilation at Vo(2max) was 30% higher, P < 0.05 (78% higher, per kg), arterial Pco(2) was 4.5 mmHg (17%) lower, P < 0.05, while total pulmonary vascular resistance was (insignificantly) 5% lower (30% lower, per kg) in HCR. The smaller mass of HCR animals was due mostly to a smaller body frame rather than to a lower fat mass. These findings show that by generation 15, lung size in smaller HCR rats is not reduced in concert with their smaller body size, but has remained similar to that of LCR, supporting the hypothesis that continued selection for increased endurance capacity requires relatively larger lungs, supporting greater ventilation, gas exchange, and pulmonary vascular conductance.

CT Quantification of Emphysema in Young Subjects with No Recognizable Chest Disease

The purpose of this prospective study was to evaluate volumetric CT emphysema quantification (CT densitovolumetry) in a young population with no recognizable lung disease. A cohort of 30 nonsmoking patients with no recognizable lung disease (16 men, 14 women; age range, 19-41 years) underwent inspiratory and expiratory CT, after which the data were postprocessed for volumetric quantification of emphysema (threshold, -950 HU). Correlation was tested for age, weight, height, sex, body surface area (BSA), and physical activity. Normal limits were established by mean +/- 1.96 SD. No correlation was found between the measured volumes and age or physical activity. Correlation was found between BSA and normal lung volume in inspiration (r = 0.69, p = 0.000), shrink volume (i.e., difference in total lung volume in inspiration and in expiration) (r = 0.66, p = 0.000), and percentage of shrink volume (r = 0.35, p = 0.05). For an alpha error of 5%, the limits of normality based on this sample are percentage of emphysema in inspiration, 0.35%; percentage of emphysema in expiration, 0.12%; and maximum lung volume in expiration, 3.6 L. The maximum predicted percentage of shrink volume can be calculated as %SV = 29.43% + 16.97% x BSA (+/- 1.96 x 7.61%). Young healthy nonsmokers with no recognizable lung disease can also show a small proportion of emphysematous-like changes on CT densitovolumetry when a threshold of -950 HU is used. Reference values should be considered when applying the technique for early detection or grading of emphysema and when studying aging lungs.

Regional and overall ventilation inhomogeneities in preterm and term-born infants

We compared ventilation inhomogeneity assessed by electrical impedance tomography (EIT) and multiple breath washout (MBW) in preterm and term-born infants. We hypothesised that EIT measurements in spontaneously breathing infants are repeatable and that differences in regional ventilation distribution measured by EIT can distinguish between preterm and term-born infants. Cross-sectional group comparison study. Lung function laboratory at a University Children's Hospital. Seventeen healthy term-born and 15 preterm infants at a matched postmenstrual age of 44 weeks. We concurrently measured ventilation inhomogeneity by EIT, ventilation inhomogeneity (LCI) and functional residual capacity (FRC) by MBW and tidal breathing variables during unsedated quiet sleep. EIT measurements were highly repeatable (coefficient of variation 3.6%). Preterm infants showed significantly more ventilation of the independent parts of the lungs compared to healthy term-born infants assessed by EIT (mean difference 5.0, 95 CI 1.3-8%). Whereas the two groups showed no differences in lung volumes or ventilation inhomogeneities assessed by MBW, EIT discriminated better between term and preterm infants. (FRC/kg: mean difference 1.1 mL, 95% CI -1.4-3.8 mL; LCI: mean difference 0.03, 95% CI -0.32-0.25). EIT shows distinct differences in ventilation distribution between preterm and term-born infants, which cannot be detected by MBW. Although preterm infants are capable of dynamically maintaining overall functional residual volume and ventilation distribution, they show some spatial differences from fullterm infants.

Lung Volume During Swallowing: Single Bolus Swallows in Healthy Young Adults

This study examined the relationship between swallowing and lung volume initiation in healthy adults during single swallows of boluses differing in volume and consistency. Differences in lung volume according to respiratory phase surrounding the swallow were also assessed. Nine men and 11 women between the ages of 19 and 28 years served as study participants. Lung volume and respiratory phase data were recorded as each participant completed 5 trials each of 10-mL and 20-mL water boluses by cup, and thin and thick paste boluses by spoon, presented in randomized order. Significant differences in lung volume at swallow initiation were found based on bolus consistency but not on bolus volume. No differences were found for lung volume initiation based on the respiratory phase surrounding the swallow or for the respiratory pattern based on bolus volume or consistency. Findings of this study extend the existing knowledge base regarding the interaction of the swallow and respiratory systems by identifying targeted lung volumes at swallow initiation. In addition to other swallow-related biomechanical events and respiratory phase relationships surrounding a swallow, the lung volume at swallow initiation may be an important consideration when investigating swallow physiology and physiopathy.

Hering–Breuer reflex, lung volume and position in prematurely born infants

To investigate the effect of position on the strength of the Hering-Breuer reflex in prematurely born infants and determine whether any differences seen were related to differences in lung or tidal volume between positions. Position related differences in the strength of the Hering-Breuer reflex relate to differences in lung or tidal volume. Prospective observational study. PATIENT/SUBJECT SELECTION: Eighteen infants, median gestational age 30 (range 25-32) weeks were studied. Infants were examined in the supine and prone position, each position was maintained for 2 hr. At the end of each 2-hr period, the strength of the Hering-Breuer reflex was assessed by determining the prolongation of expiration following an end inspiratory occlusion. In addition, tidal volume and functional residual capacity (FRC) were assessed in each position. The strength of the Hering-Breuer reflex was greater (P = 0.01) and the mean FRC was higher (P < 0.0001) in the prone compared to the supine position. The position related differences in the strength of the reflex correlated significantly with position related differences in FRC (P = 0.05). The Hering-Breuer reflex is stronger in the prone compared to the supine position. Our results suggest this is explained by position related differences in lung volume.

MR Relative Fetal Lung Volume in Congenital Diaphragmatic Hernia: Survival and Need for Extracorporeal Membrane Oxygenation

To retrospectively evaluate the accuracy of the absolute fetal lung volume (FLV) measured at magnetic resonance (MR) imaging and seven formulas for calculating relative FLV to predict neonatal survival and the need for extracorporeal membrane oxygenation (ECMO) in fetuses with congenital diaphragmatic hernia (CDH). This retrospective study was approved by the research ethics committee, and informed consent was received from all mothers for previous prospective studies. In total, 68 fetuses with CDH were assessed by using MR image FLV measurement within 23-39 weeks gestation. The relative FLV was expressed as a percentage of the predicted lung volume calculated with biometric parameters according to seven formulas previously described in the literature. Applying the area under the curve (AUC), the various relative FLVs and the absolute FLV were investigated for their prognostic accuracy to predict neonatal survival and the need for ECMO therapy. All relative FLVs and the absolute FLV revealed a significant difference in mean lung volume between neonates who survived and neonates who did not survive (P = .001 to P < .001) and measurement accuracy was excellent for each method (AUC, 0.800-0.900). For predicting neonatal ECMO requirement, differences in FLVs were smaller but still significant (P = .05 to <.009) and measurement accuracy was acceptable throughout (AUC, 0.653-0.739). The various relative FLVs and the absolute FLV measured at MR planimetry are each highly valuable in predicting survival in fetuses with CDH. For predicting whether neonatal ECMO therapy is required, the accuracy of the absolute FLV (AUC, 0.68) and that of the relative FLVs (AUC, 0.653-0.739) was acceptable.

Reliability, repeatability and reproducibility: analysis of measurement errors in continuous variables

Reliability, repeatability and reproducibility: analysis of measurement errors in continuous variables

Differences between Finnish and European reference values for pulmonary diffusing capacity

Objectives. To compare European (ECSC) and Finnish reference values for single-breath diffusing capacity for carbon monoxide (DL(CO)).Study Design. Finnish reference values for DL(CO), specific diffusing capacity (DL(CO)/VA) and total lung capacity (TLC) were compared with ECSC reference values calculated for different age, height and weight groups. In addition, 10 healthy subjects performed the test with both the Finnish method (inhaled volume 90% of vital capacity, VC) and the ECSC method (inhaled volume 100% of VC).Methods. Percentual differences between the ECSC and Finnish reference values for DL(CO), TLC and DL(CO)/VA were calculated. The results of measurements of DL(CO) and TLC by using inhaled volume of 100% of VC and 90% of VC in 10 healthy subjects were compared.Results. The Finnish DL(CO) reference value for men was 3–12% and for women 8-20% smaller than the ECSC reference value. TLC calculated according to Finnish equations was 2-14% greater than that based on ECSC equations. The ECSC reference value for DL(CO)/VA was about 20% greater than the Finnish reference value in men and 30% greater than that in women. The 10 healthy subjects had significantly higher DL(CO) when measured according to the ECSC method as compared with the Finnish one (p & 0.004).Conclusions. The Finnish reference values for DL(CO) were about 10% smaller, but TLC 10% and DL(CO)/VA 20–30% greater than ECSC reference values in subjects of the same age, height, weight and gender. The difference in DL(CO) is explained by the different inhaled lung volumes used in the two methods, the difference in lung volumes probably arising from ethnic differences in thoracic cavity.

Monitoring of Smoking-induced Emphysema with CT in a Lung Cancer Screening Setting: Detection of Real Increase in Extent of Emphysema

To retrospectively establish the minimum increase in emphysema score (ES) required for detection of real increased extent of emphysema with 95% confidence by using multi-detector row computed tomography (CT) in a lung cancer screening setting. The study was a substudy of the NELSON project that was approved by the Dutch Ministry of Health and the ethics committee of each participating hospital, with patient informed consent. For this substudy, original approval and informed consent allowed use of data for future research. Among 1684 men screened with low-dose multi-detector row CT (30 mAs, 16 detector rows, 0.75-mm section thickness) between April 2004 and March 2005, only participants who underwent repeat multi-detector row CT with the same scanner after 3 months because of an indeterminate pulmonary nodule were included. Extent of emphysema was considered to remain stable in this short period. Extent of low-attenuation areas representing emphysema was computed for repeat and baseline scans as percentage of lung volume below three attenuation threshold values (-910 HU, -930 HU, -950 HU). Limits of agreement were determined with Bland-Altman approach; upper limits were used to deduce the minimum increase in ES required for detecting increased extent of emphysema with 95% probability. Factors influencing the limits of agreement were determined. In total, 157 men (mean age, 60 years) were included in the study. Limits of agreement for differences in total lung volume between repeat and baseline scans were -13.4% to +12.6% at -910 HU, -4.7% to +4.2% at -930 HU, and -1.3% to +1.1% at -950 HU. Differences in ES showed weak to moderate correlation with variation in level of inspiration (r=0.20-0.49, P<.05). Scanner calibration could be excluded as a factor contributing to variation in ES. Increase in ES required to detect increased extent of smoking-related emphysema with 95% probability varies between 1.1% of total lung volume at -950 HU and 12.6% at -910 HU for low-dose multi-detector row CT. Clinical trial registration no. ISRCTN63545820.

Computed Tomographic-Based Volumetric Reconstruction of the Pulmonary System in Scoliosis

Scoliosis has been associated with reduced pulmonary capacity; however, the source of the reduction in capacity (left, right, or both lungs) is not clear. The objective of this study was to investigate trends in left, right, and total lung volume and left/right lung volume asymmetry with spinal curve severity in scoliosis. Three-dimensional volumetric reconstruction of the pulmonary system was performed on existing preoperative computed tomographic (CT) scans for 28 idiopathic scoliosis patients. Left, right, and total lung volumes, and left/right lung volume ratios were calculated and correlated with the following spinal curve parameters: major Cobb angle, rib hump, number of vertebrae in the major curve, most cephalad vertebra in the major curve, and thoracic kyphosis. Left/right lung volume ratio increases significantly with increasing rib hump. Left, right, and total lung volumes were significantly correlated with rib hump and number of vertebrae in the major curve (P < 0.05), and near-significantly correlated with most cephalad vertebra in the major curve (P < 0.10). Shorter, higher, more rotated thoracic curves therefore restrict lung volume more than longer, lower, less rotated curves. The mean lung volume ratio for scoliosis patients was lower than for age-matched controls (P < 0.10). CT-based volumetric reconstruction of the pulmonary system in scoliosis patients shows differences in both lung volumes and lung volume ratios compared with normal controls.

Regional lung volume changes in children with acute respiratory distress syndrome during a derecruitment maneuver*

Regional differences in lung volume have been described in adults with acute respiratory distress syndrome, but it remains unclear to what extent they occur in children. To quantify regional alveolar collapse that occurred during mechanical ventilation during a standardized suctioning maneuver, we evaluated regional and global relative impedance changes (relative DeltaZ) in children with acute respiratory distress syndrome using electrical impedance tomography. Prospective observational trial. A 30-bed pediatric intensive care unit. Six children with acute respiratory distress syndrome. Standardized suctioning maneuver. By comparing layers from nondependent (layers 1 and 2) to dependent lung areas (layers 3 and 4), it was demonstrated that the middle layers (2 and 3) had the greatest ventilation-induced change in relative DeltaZ; layer 4 showed the least ventilation-induced change in relative DeltaZ. During suctioning, layers 1, 2, and 3 showed a negative change in relative DeltaZ, whereas layer 4 showed no significant change in relative DeltaZ. The derecruitment-induced change in relative DeltaZ representing the lung-volume loss was -9.8 (-3.0 mL/kg) during the first suctioning maneuver, -16.1 (-5.4 mL/kg) during the second, and -21.7 (-7.4 mL/kg) during the third. The ventilation-induced change in relative DeltaZ during mechanical ventilation remained unchanged after suctioning (mean change in relative DeltaZ before vs. after suctioning, 40.1 +/- 9.1 vs. 41.4 +/- 10.8; p = .30). Dynamic compliance was 11.8 +/- 6.1 mL.cm H2O before and 11.8 +/- 6.9 mL.cm H2O after the suctioning sequence (p = .90). Considerable regional heterogeneity was present during ventilation and a derecruitment maneuver. Significantly lower change in relative DeltaZ in the most dependent lung regions suggests alveolar collapse during ventilation before suctioning.

TNF-a and IL-10 levels in tracheobronchial lavage of ventilated preterm infants and subsequent lung function

The role of airway inflammation in ventilated preterm newborns and the risk factors associated with the development of chronic lung disease are not well understood. Our objective was to analyze the association of the airway inflammatory response in ventilated preterm infants by serial measurements of TNF-alpha and IL-10 in tracheobronchial lavage (TBL) with perinatal factors and lung function measured early in life. A series of TBL samples were collected from ventilated preterm infants (less than 32 weeks of gestational age) and concentrations of TNF-alpha and IL-10 were measured by ELISA. Pulmonary function tests were performed after discharge by the raised volume rapid compression technique. Twenty-five subjects were recruited and 70 TBL samples were obtained. There was a significant positive association between TNF-alpha and IL-10 levels and length of time between the rupture of the amniotic membranes and delivery (r = 0.65, P = 0.002, and r = 0.57, P < 0.001, respectively). Lung function was measured between 1 and 22 weeks of corrected age in 10 patients. Multivariable analysis with adjustment for differences in lung volume showed a significant negative association between TNF-alpha levels and forced expiratory flow (FEF(50); r = -0.6; P = 0.04), FEF(75) (r = -0.76; P = 0.02), FEF(85) (r = -0.75; P = 0.03), FEF(25-75) (-0.71; P = 0.02), and FEV(0.5) (r = -0.39; P = 0.03). These data suggest that TNF-alpha levels in the airways during the first days of life were associated with subsequent lung function abnormalities measured weeks or months later.