Pulmonary air trapping during two-lung and one-lung ventilation

OBJECTIVE

Evaluation of the magnitude of pulmonary air trapping during routine thoracic surgery and single-lung transplantation.

DESIGN

Prospective study on consecutive patients.

SETTING

Single institution, university hospital.

PARTICIPANTS

Sixteen patients with no or moderate obstructive lung disease undergoing routine thoracic surgery (group 1), six patients with severe emphysema (group 2), and six patients with severe fibrosis (group 3) undergoing single-lung transplantation.

INTERVENTIONS

Occlusion maneuver timed at the end of expiration to measure auto-positive end-expiratory pressure (auto-PEEP) and trapped volume (delta FRC). The maneuver was performed during two-lung ventilation in supine (2LV supine) and lateral decubitus (2LV lateral) positions and during one-lung ventilation (OLV) in lateral decubitus position. At the same time, airway pressures and PaO2 measurements were performed.

MEASUREMENTS AND MAIN RESULTS

In group 1, consistent values of auto-PEEP and delta FRC occurred only during OLV: 4.8 +/- 2.5 cm H2O and 109 +/- 61 mL (mean +/- standard deviation). In group 2, auto-PEEP and delta FRC values were 11.7 +/- 6.9 cm H2O and 355 +/- 125 mL during 2LV supine, 8.8 +/- 5.7 cm H2O and 320 +/- 122 mL during 2LV lateral, and 15.9 +/- 3.9 cm H2O and 284 +/- 45 mL during OLV. In group 3, pulmonary air trapping was low. For the three groups together, auto-PEEP and delta FRC (p < 0.0001) related inversely to the ratio of forced expired volume in 1 second (FEV1) to forced vital capacity (FVC) expressed in percent (FEV1/FVC%) during OLV. In contrast, there was no correlation between PaO2 and auto-PEEP or delta FRC.

CONCLUSION

Pulmonary air trapping must be suspected in patients with no or moderate obstructive lung disease during OLV and in those with severe obstructive disease as soon as 2LV is initiated.

Sleep quality, carbon dioxide responsiveness and hypoxaemic patterns in nocturnal hypoxaemia due to chronic obstructive pulmonary disease (COPD) without daytime hypoxaemia

In order to clarify whether nocturnal hypoxaemia (arterial oxygen saturation, SaO2 < 90%) may exist in the long-term before daytime hypoxaemia (PaO2 < 8.0 kPa) occurs in chronic obstructive pulmonary disease (COPD), 21 patients with stable severe COPD without daytime hypoxaemia (PaO2 > or = 8.0 kPa) were studied prospectively. Subjects were monitored twice by polysomnography (PSG) 12 months apart. Spirometry was performed, and diffusion capacity (DLCO) and hypercapnic respiratory drive response delta PI0.1 delta PCO2(-1)) were measured during the daytime in conjunction with polysomnography. At the start of the study our subjects had FEV1 %P (FEV1 as a percentage of predicted value) of 26.1 +/- 7.2%, a mean nocturnal nadir SaO2 of 83 +/- 5%, and a mean SaO2 during nocturnal hypoxaemic episodes of 88.0 +/- 0.7%. The patients' delta PI0.1 delta PCO2(-1) was 1.8 +/- 1.4 cm H2O kPa-1 (within the normal range). For the entire study group, no significant change in any lung function or blood gas parameter was noted during the year of observation, and nocturnal SaO2 remained unaltered. Stage I sleep decreased (P < 0.05) after 12 months. Prolonged stage I sleep was associated with nocturnal hypoxaemia at the second PSG. Five subjects developed daytime hypoxaemia and they showed poorer lung function but similar nocturnal hypoxaemia and delta PI0.1 delta PCO2(-1) level compared to the rest of the patients. Patients with sudden SaO2 dips had more pronounced nocturnal hypoxaemia and prolonged wakefulness than 'non-dippers'. In conclusion, the mean level of nocturnal hypoxaemia may persist unaltered for at least 1 yr. COPD patients with exclusively nocturnal hypoxaemia have a hypercapnic drive response within the normal range. Prolonged nocturnal hypoxaemia and reduced whole night oxygenation are associated with increased superficial sleep. Sleep fragmentation and high carbon dioxide sensitivity may be important defence mechanisms against sleep-related hypoxaemia. The appearance of daytime hypoxaemia is preceded by a substantial deterioration in lung function, but by only a minor deterioration of nocturnal hypoxaemia.

[The effects of inhaled bronchodilators on central inspiratory drive in patients with COPD]

OBJECTIVE

To evaluate the effects of inhaled bronchodilators on the central inspiratory drive in patients with COPD.

METHODS

91 patients with COPD were divided into three groups (A, B, C) randomly. Lung functions and P(0.1) were measured at baseline and 20 min and 60 min after inhalation (A: albuterol; B: iprotropium; C: albuterol + iprotropium).

RESULTS

P(0.1) decreased after inhalation in all three groups (P < 0.05 approximately 0.001). A positive correlation between DeltaP(0.1) and DeltaFRC was found in the three groups (r = 0.4325 - 0.5230, P < 0.05 approximately 0.01). V(E)/P(0.1) increased in the three groups after inhalation (P < 0.05 approximately 0.005). There was significant improvement of V(E)/P(0.1) in group B and C as compared with that of group A (P < 0.05, P < 0.001); There was a different correlative factor with V(E)/P(0.1) in group B and C.

CONCLUSIONS

(1) P(0.1) decreased after inhalation, It may be caused by decreased FRC. (2) V(E)/P(0.1) became appropriate after inhalation in all groups; The improvement in group B and C was superior to that of group A. There may be different mechanisms to improve V(E)/P(0.1) by different inhalators.

Expiratory and inspiratory chest computed tomography and pulmonary function tests in cigarette smokers

This study evaluated small airway dysfunction and emphysematous destruction of lung parenchyma in cigarette smokers, using chest expiratory high-resolution computed tomography (HRCT) and pulmonary function tests (PFT). The degree of emphysematous destruction was classified by visual scoring (VS) and the average HRCT number at full expiration/full inspiration (E/I ratio) calculated in 63 male smokers and 10 male nonsmokers (group A). The Brinkman smoking index (BI), defined as cigarettes x day(-1) x yrs, was estimated. Sixty-three smokers were divided into three groups by PFT: group B1 (n=7), with normal PFT; group B2 (n=21), with diffusing capacity of the lung for carbon monoxide (DL,CO) > or = 80% predicted, forced expiratory volume in one second (FEV1) < 80% pred and/or residual volume (RV) > 120% pred; and group B3 (n=35), with DL,CO < 80% pred, FEV1 < 80% pred and/or RV > 120% pred. Heavy smokers (BI > or = 600) (n=48) showed a significant increase in emphysema by both VS and E/I. E/I was significantly elevated in both group B2 (mean+/-SD 0.95+/-0.05) and B3 (0.96+/-0.06) compared with group B1 (0.89+/-0.03). VS could not differentiate group B2 (3.9+/-5.0) from B1 (1.1+/-1.6). These findings suggest that the expiration/inspiration ratio reflects hyperinflation and airway obstruction, regardless of the functional characteristics of emphysema, in cigarette smokers.

Comparability of albuterol delivered by a piezoelectric device versus metered dose inhaler in patients with chronic obstructive airways disease

In recent years, there has been increased interest in developing propellant-free inhalers for the treatment of patients with chronic obstructive airways disease. Various powder inhalators have been developed. A recent alternative to the dose-metered aerosols has been produced using the piezoelectric effect. This double-blind, double-dummy, randomized, dual-dose, four-period crossover study was designed to compare the effect of albuterol inhaled from the piezoelectric device (PED) and albuterol inhaled from the metered dose inhaler (MDI). The primary efficacy variables were forced expiratory volume in one second (FEV1) and area under the curve (AUC). Although we found a statistically significant device effect for the primary efficacy variables, the two treatments (PED [test] and MDI [reference]) are comparable. The only variable for which comparability was not found was time of onset. We found no dose differences. In conclusion, we found a similar effect of albuterol inhaled by a PED versus an MDI in patients with chronic obstructive airways disease.

Both intravenous and inhaled lidocaine attenuate reflex bronchoconstriction but at different plasma concentrations

Intravenous lidocaine can attenuate bronchial hyperreactivity. However, lidocaine inhalation might yield the same or better results at higher airway and lower lidocaine plasma concentrations. Therefore, we tested in awake volunteers with bronchial hyperreactivity the effect of lidocaine on histamine-induced bronchoconstriction administered either intravenously or as an aerosol. After approval of the local ethics committee, 15 volunteers were enrolled in this placebo-controlled, double-blinded, randomized study. Volunteers were selected by showing a decrease in FEV1 greater than 20% of baseline (PC20) in response to histamine inhalation. On three different days the challenge was repeated after pretreatment with either intravenous lidocaine, inhaled lidocaine, or placebo. Blood samples for determination of lidocaine plasma concentration were drawn. Comparisons were made using the Friedman and Wilcoxon signed-rank tests. Baseline PC20 was 6.4 +/- 1.1 mg. ml-1. Both inhalation of lidocaine and intravenous administration significantly increased PC20 to 14.8 +/- 3.5 mg. ml-1 and 14.2 +/- 2. 5 mg. ml-1, respectively (p = 0.0007). Peak plasma lidocaine concentrations at the end of challenges were 0.7 +/- 0.1 microg. ml-1 (inhaled) and 2.2 +/- 0.1 microg. ml-1 (i.v.). However, 7 of 15 subjects showed an initial decrease of FEV1 greater than 5% following lidocaine inhalation. While both intravenous as well as inhaled lidocaine attenuate reflex bronchoconstriction significantly, lidocaine plasma concentrations are significantly lower after inhalation. However, the high incidence of initial bronchoconstriction to lidocaine inhalation may limit its use in patients with asthma and thus offers therapeutic advantages for intravenous lidocaine.

A pilot study of low-dose erythromycin in bronchiectasis

Patients with bronchiectasis suffer from sputum production, recurrent exacerbations, and progressive airway destruction. Erythromycin is effective in diffuse panbronchiolitis, another suppurative airway disorder, although its efficacy is unknown in idiopathic bronchiectasis. A double-blind placebo-controlled study was therefore conducted to evaluate the effects of 8-week administration of low dose erythromycin (500 mg b.i.d.) in steady-state idiopathic bronchiectasis. Patients in the erythromycin group (n=11, 8 female, mean age 50+/-15 yrs), but not the placebo group (n=10, 8 female, mean age 59+/-16 yrs) had significantly improved forced expiratory volume in one second, forced vital capacity and 24-h sputum volume after 8 weeks (p<0.05). There was no parallel improvement in sputum pathogens, leukocytes, interleukin (IL)-1alpha and IL-8, tumour necrosis factor-alpha, or leukotriene B4. The results of this pilot study show that low-dose erythromycin improves lung function and sputum volume in bronchiectasis. Further studies are indicated to evaluate the efficacy of long-term erythromycin therapy in bronchiectasis.

Decline in FEV1 related to smoking status in individuals with severe alpha1-antitrypsin deficiency (PiZZ)

Severe alpha1-antitrypsin (AAT) deficiency predisposes to emphysema development. Highly variable rates of decline in lung function are reported in PiZZ individuals. The annual decline in forced expiratory volume in one second (FEV1; delta FEV1) was analysed in relation to smoking status in a cohort of 608 adult PiZZ individuals included in the Swedish national AAT deficiency register. Delta FEV1 was analysed in 211 never-smokers, in 351 exsmokers, and in 46 current smokers after performing at least two spirometries during a follow-up time of 1 yr or longer (median 5.5 yrs, range 1-31). The adjusted mean delta FEV1 in never-smokers was 47 mL x yr(-1) (95% confidence interval (CI) 41-53 mL x yr(-1)), 41 mL x yr(-1) (95% CI 36-48 mL x yr(-1)) in exsmokers, and 70 mL x yr(-1) (95% CI 58-82 mL x yr(-1)) in current smokers. A dose-response relationship was found between cigarette consumption and delta FEV1 in current smokers and exsmokers. In never-smokers, a greater delta FEV1 was found after 50 yrs of age than before. No sex differences were found in delta FEV1. In conclusion, among PiZZ individuals, the change in forced expiratory volume in one second is essentially the same in never-smokers and exsmokers. Smoking is associated with a dose-dependent increase in the change in forced expiratory volume in one second.

Orally exhaled nitric oxide levels are related to the degree of blood eosinophilia in atopic children with mild-intermittent asthma

Increased levels of nitric oxide have been found in expired air of patients with asthma, and these are thought to be related to the airway inflammatory events that characterize this disorder. Since, in adults, bronchial inflammatory changes are present even in mild disease, the present study was designed to evaluate whether a significant proportion of children with mild-intermittent asthma could have increased exhaled air NO concentrations. Twenty-two atopic children (aged 11.1+/-0.8 yrs) with mild-intermittent asthma, treated only with inhaled beta2-adrenoreceptor agonists on demand and 22 age-matched controls were studied. NO concentrations in orally exhaled air, measured by chemiluminescence, were significantly higher in asthmatics, as compared to controls (19.4+/-3.3 parts per billion (ppb) and 4.0+/-0.5 ppb, respectively; p<0.01). Interestingly, 14 out of 22 asthmatic children had NO levels >8.8 ppb (i.e. >2 standard deviations of the mean in controls). In asthmatic patients, but not in control subjects, statistically significant correlations were found between exhaled NO levels and absolute number or percentage of blood eosinophils (r=0.63 and 0.56, respectively; p<0.01, each comparison). In contrast, exhaled NO levels were not correlated with forced expiratory volume in one second (FEV1) or forced expiratory flows at 25-75% of vital capacity (FEF25-75%) or forced vital capacity (FVC), either in control subjects, or in asthmatic patients (p>0.1, each correlation). These results suggest that a significant proportion of children with mild-intermittent asthma may have airway inflammation, as shown by the presence of elevated levels of nitric oxide in the exhaled air. The clinical relevance of this observation remains to be established.

Subcellular adaptation of the human diaphragm in chronic obstructive pulmonary disease

Pulmonary hyperinflation impairs the function of the diaphragm in patients with chronic obstructive pulmonary disease (COPD). However, it has been recently demonstrated that the muscle can counterbalance this deleterious effect, remodelling its structure (i.e. changing the proportion of different types of fibres). The aim of this study was to investigate whether the functional impairment present in COPD patients can be associated with structural subcellular changes of the diaphragm. Twenty individuals (60+/-9 yrs, 11 COPD patients and 9 subjects with normal spirometry) undergoing thoracotomy were included. Nutritional status and respiratory function were evaluated prior to surgery. Then, small samples of the costal diaphragm were obtained and processed for electron microscopy analysis. COPD patients showed a mean forced expiratory volume in one second (FEV1) of 60+/-9% predicted, a higher concentration of mitochondria (n(mit)) in their diaphragm than controls (0.62+/-0.16 versus 0.46+/-0.16 mitochondrial transections (mt) x microm(-2), p<0.05). On the other hand, subjects with air trapping (residual volume (RV)/total lung capacity (TLC) >37%) disclosed not only a higher n(mit) (0.63+/-0.17 versus 0.43+/-0.07 mt x microm(-2), p<0.05) but shorter sarcomeres (L(sar)) than subjects without this functional abnormality (2.08+/-0.16 to 2.27+/-0.15 microm, p<0.05). Glycogen stores were similar in COPD and controls. The severity of airways obstruction (i.e. FEV1) was associated with n(mit) (r=-0.555, p=0.01), while the amount of air trapping (i.e. RV/TLC) was found to correlate with both n(mit) (r=0.631, p=0.005) and L(sar) (r=-0.526, p<0.05). Finally, maximal inspiratory pressure (PI,max) inversely correlated with n(mit) (r=-0.547, p=0.01). In conclusion, impairment in lung function occurring in patients with chronic obstructive pulmonary disease is associated with subcellular changes in their diaphragm, namely a shortening in the length of sarcomeres and an increase in the concentration of mitochondria. These changes form a part of muscle remodelling, probably contributing to a better functional muscle behaviour.

Development of pulmonary hypertension after lung volume reduction surgery

This prospective, longitudinal study was designed to assess the hemodynamic changes occurring in patients who undergo lung volume reduction surgery (LVRS). Patients with emphysema treated with LVRS underwent hemodynamic evaluation before and after surgery. The study group consisted of nine patients with an average age of 64.4 yr. FEV1 rose significantly from 0.64 preoperatively to 0.99 L postoperatively. After surgery, pulmonary artery (PA) systolic pressure rose to 47.9 +/- 12.4 mm Hg, meeting criteria for development of pulmonary hypertension. In six patients, the elevation in PA pressure was attributed to an increase in the pulmonary vascular resistance, but for all nine patients the change was not statistically significant. The pulmonary artery occulsion pressure (PAOP) did not change postoperatively. There was no correlation of PAOP with global left ventricular ejection fraction. While preoperatively there was a negative correlation between symptoms (Mahler dyspnea index) and PA pressure, after surgery the change in PA pressures did not correlate with the change in symptoms (Mahler transitional dyspnea index). We concluded that development of pulmonary hypertension may occur after LVRS in patients whose symptomatic status improves and in whom this condition was not present preoperatively.

Growth failure in cystic fibrosis

OBJECTIVE

The aim of this study was to describe and compare the nutritional status of children aged 0-18 years attending the cystic fibrosis (CF) clinic at the Royal Children's Hospital, Brisbane, Australia, as outpatients in 1986 and 1996.

METHODOLOGY

The heights, weights and pulmonary function of children attending the CF clinic as outpatients in 1986 (n = 97) and 1996 (n = 227) were retrospectively analysed using a computerized database maintained by the CF clinic. The heights and weights were analysed in terms of z scores for height for age (HAZ), weight for age (WAZ) and weight for height (WHZ). Pulmonary function data is not available for all children. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and forced mid expiratory flows (FEF) were expressed as a percentage of predicted and are presented here.

RESULTS

The 1986 sample consisted of 41 males (age range 0.18-14.59 years, mean age 6.52 (4.33)) and 56 females (age range 0.15-14.97 years, mean age 7.75 (3.70)). The 1996 sample consisted of 111 males (age range 0.09-17.97 years, mean age 8.80 (5.49)) and 114 females (age range 0.12-17.98 years, mean age 8.49 (5.26)). In 1986, males were shorter than females (P = 0.0096) and females had a lower mean FVC than males (P = 0.0438). In 1996, males were shorter, lighter and more wasted than females (P = 0.0357, P = 0.0034 and P = 0.0273, respectively) and females had a lower mean FEV1 and mean FVC than males (P = 0.0176 and P = 0.0079, respectively). Males in 1996 were lighter and more wasted than males in 1986 (P = 0.0023 and P = 0.0139, respectively) and had a lower mean FEV1, mean FVC and mean FEF (P < 0.0001, P = 0.0012 and P = 0.0069, respectively). Females in 1996 were shorter and lighter than females in 1986 (P = 0.0273 and P = 0.0405, respectively) and had a lower mean FEV1, mean FVC and mean FEF (P < 0.0001, P < 0.0001 and P < 0.0001, respectively). When subjects were classified according to FEV1 (FEV1 > or = 75% or FEV1 < 75%), there were no significant differences in z scores between the 1986 group and 1996 group. Similarly, when the 1986 group were matched for gender and FEV1 with the 1996 group, there were no significant differences in z scores for males or females.

CONCLUSIONS

It is suggested that the apparent worsening of nutritional status among the 1996 group of CF patients is in fact due to an effect of increased survival of patients with more severe clinical symptoms. The findings from this study highlight the continuing, and in fact, worsening problem of growth failure in children with CF.

Acute effects of nebulised epoprostenol in pulmonary hypertension due to systemic sclerosis

Pulmonary hypertension often has a lethal outcome in systemic sclerosis and the treatment is challenging. Epoprostenol is a potent pulmonary vasodilator and its efficacy has been demonstrated when delivered by the intravenous and aerosolized routes. We report the haemodynamic and functional benefits of epoprostenol administered by inhalation to a spontaneously breathing patient with partially reversible pulmonary hypertension due to systemic sclerosis. Aerosolized epoprostenol, equivalent to the maximum tolerated intravenous dose (31.2 micrograms), produced a 58% fall in pulmonary vascular resistance, increased the cardiac output by 42% and improved functional performance by one MET (3.5 ml kg-1 min-1 of oxygen uptake) without any significant side-effects. Selective distribution of epoprostenol by the inhaled route may offer a new strategy for treatment of pulmonary hypertension.

Exhaled and nasal NO levels in allergic rhinitis: relation to sensitization, pollen season and bronchial hyperresponsiveness

Exhaled nitric oxide is a potential marker of lower airway inflammation. Allergic rhinitis is associated with asthma and bronchial hyperresponsiveness. To determine whether or not nasal and exhaled NO concentrations are increased in allergic rhinitis and to assess the relation between hyperresponsiveness and exhaled NO, 46 rhinitic and 12 control subjects, all nonasthmatic nonsmokers without upper respiratory tract infection, were randomly selected from a large-scale epidemiological survey in Central Norway. All were investigated with flow-volume spirometry, methacholine provocation test, allergy testing and measurement of nasal and exhaled NO concentration in the nonpollen season. Eighteen rhinitic subjects completed an identical follow-up investigation during the following pollen season. Exhaled NO was significantly elevated in allergic rhinitis in the nonpollen season, especially in perennially sensitized subjects, as compared with controls (p=0.01), and increased further in the pollen season (p=0.04), mainly due to a two-fold increase in those with seasonal sensitization. Nasal NO was not significantly different from controls in the nonpollen season and did not increase significantly in the pollen season. Exhaled NO was increased in hyperresponsive subjects, and decreased significantly after methacholine-induced bronchoconstriction, suggesting that NO production occurs in the peripheral airways. In allergic rhinitis, an increase in exhaled nitric oxide on allergen exposure, particularly in hyperresponsive subjects, may be suggestive of airway inflammation and an increased risk for developing asthma.

[House dust mite allergens and mite allergy in Copenhagen dwellings. A cross-sectional study]

The aim of the study was to investigate the influence of various environmental factors on occurrence of house dust mite allergens and the influence of allergen exposure on mite allergy. Ninety-two persons from a population study filled in a questionnaire, were skin prick and lung function tested and dust samples were collected from their mattresses for analyses. Two out of five patients with asthma had a positive skin reaction to house dust mite allergen in contrast to five out of 87 non-asthmatics. Fifty-nine per cent of the dust samples contained (group 1) mite allergen > 2 micrograms/g dust. Such mattresses were older (median 7 years, range 1-22) than mattresses with less allergen (median 4 years, range 1-20). In the six bedrooms reported to be humid or mouldy, mattresses contained high concentration of mite allergens. No other parameter investigated could predict the allergen contents. In almost all cases dust analyses are crucial to be able to advise patients with house dust mite allergy.

Functional status in pulmonary rehabilitation participants

PURPOSE

This study examined functional status abnormalities in pulmonary rehabilitation patients, its responsiveness to pulmonary rehabilitation intervention, and its relationship to patient characteristics and traditional measures of disease severity.

METHODS

One hundred sixty-four men and women age 69 years (SD +/- 8), who participated in 1 of 10 pulmonary rehabilitation programs in Connecticut, were studied pre- and postrehabilitation with the following outcome measures: (1) the 6-minute walk distance, (2) the Pulmonary Functional Status Scale (PFSS), and (3) in a subset of 60 subjects, health-related quality of life was measured using the Chronic Respiratory Disease Questionnaire (CRDQ). Patient characteristics were compared to baseline values of these measures using Spearman correlations and Wilcoxon Rank Sum tests, whereas pre- to post-changes in outcome measures were evaluated using Wilcoxon signed-ranks tests. Effect size, representing a standardized measure of change, was calculated for the PFSS.

RESULTS

The mean FEV1 was 0.95 +/- 0.50 liters (38 +/- 18% predicted). Rehabilitation resulted in significant increases in the 6-minute walk distance (24%, P < 0.001, the total PFSS scores [13%, P < 0.001, effect size 1.0]) and the total CRDQ (18% P < 0.001). The prerehabilitation function subscore and total PFSS score correlated strongly with the 6-minute walk distance (r = 0.76, 0.73; P < 0.001) and to a lesser degree with the FEV1 (r = 0.31, 0.33; P < 0.001). Males scored higher baseline scores in several PFSS subscales, the total PFSS score, and the 6-minute walk distance; females showed more improvement in some of the PFSS scores.

CONCLUSION

The 6-minute walk distance, the PFSS, and CRDQ all improved significantly with rehabilitation. Functional status, as measured by the PFSS is very strongly correlated with the 6-minute walk. Gender differences in the timed walk distance and functional status highlight the need to study this variable more thoroughly.

Spirometric indices and the risk of pulmonary barotrauma in submarine escape training

Between 1975 and 1997, a total of 115,090 ascents, from depths of between 9 and 28 m, have been made by trainees at the submarine escape training tank HMS Dolphin. During this 22-yr period, 53 incidents have occurred in which, after an ascent, the trainee required hospital or recompression therapy or both. Scrutiny of the incident records revealed unequivocal evidence of pulmonary barotrauma in six incidents with an additional four in which, despite a negligible gas burden, a confident diagnosis of acute neurologic decompression illness with short latency could be made. No causative mechanism other than arterial gas embolism following pulmonary barotrauma can be implicated in these four cases despite the absence of clinical or radiographic evidence of lung injury. In all 10 cases the forced vital capacity (FVC) of the trainees was less than the predicted value for their age and height, revealing a statistically significant (P< 0.01) association between values of FVC below predicted and pulmonary barotrauma. The median FEV1 for the 10 cases was also significantly (P < 0.05) less than the predicted value after allowing for age and height. No such association was found for the FEV1:FVC ratio. FVC would thus seem to be the measure of lung function most closely associated with increased risk of pulmonary barotrauma. Possible reasons for this finding are discussed. It is concluded that although the association between low FVC and pulmonary barotrauma is statistically significant, it is insufficiently specific for low FVC to serve as an exclusion criterion for submarine escape training.

Hyperbaric oxygen treatment and pulmonary function

Hyperbaric oxygen (HBO2) treatment exposes the lungs to the potentially toxic effect of free oxygen radicals and may lead to impairment of pulmonary function. HBO2 significantly improves wound healing in patients with osteoradionecrosis of the mandible following radiation therapy for intraoral cancer. In 18 consecutive patients with osteoradionecrosis of the mandible, pulmonary function was assessed during 6 wk of HBO2 treatment, applied daily in a monoplace chamber for 90 min and at a partial oxygen pressure of 2.4 atm abs. Pretreatment forced vital capacity (FVC) was 104 +/- 14% (mean +/- SD) of a reference population, the 1 s forced expiratory volume (FEV1) 95 +/- 20%, total lung capacity (TLC) 100 +/- 13%, and the carbon monoxide diffusing capacity (DL(CO)) 81 +/- 17% (P < 0.05, compared to reference population). These parameters remained unchanged throughout the treatment period (after 6 wk and expressed relative to the percentage of the expected value at baseline): deltaFVC: +4 +/- 8%; deltaFEV1: -2 +/- 4%; deltaTLC: +2 +/- 5%; deltaDL(CO): 0 +/- 9%; deltaRV 0 +/- 11%. It is concluded that intermittent HBO2 treatment in a monoplace chamber has no persistent effect on pulmonary function and can be offered even to patients with a reduced diffusing capacity.

Particulate matter, sulfur dioxide, and pulmonary function in never-smoking adults in Chongqing, China

Chongquing is one of the most polluted cities in China. To study the respiratory health effects of air pollution for this city, the authors monitored the ambient levels of particulate matter (PM2.5) and sulfur dioxide (SO2) in urban and suburban areas and performed pulmonary function testing on 1,075 adults 35 to 60 years of age who had never smoked and did not use coal stoves for cooking or heating. The mean concentration of SO2 in the urban areas (213 micrograms/m3) was twice as high as that in suburban areas (103 micrograms/m3). Mean PM2.5 levels were high in both urban (143 micrograms/m3) and suburban (139 micrograms/m3) areas. A generalized additive model was used to estimate the differences between the two areas in FEV1, FVC, and FEV1/FVC%, with adjustment for potential confounding factors, including sex, age, height, education, passive smoking, and occupational exposures to dust, gas, or fumes. Estimated differences in FEV1 between the urban and suburban areas were 199 mL (SE = 50 mL) for men and 87 mL (SE = 30 mL) for women, both statistically significant. When the men and women were pooled, the estimated difference in FEV1 was 126 mL (SE = 27 mL). Similar trends were observed for FVC and FEV1/FVC%. After exclusion of 104 subjects with histories of occupational exposures to dust, gas, or fumes, the estimated difference was some-what smaller than that of the total samples. However, the effects on FEV1 and FEV1/FVC% remained significant for both men and women.

Clinical outcomes of newborn screening for cystic fibrosis

AIM

To determine how early diagnosis of cystic fibrosis, using neonatal screening, affects long term clinical outcome.

METHODS

Fifty seven children with cystic fibrosis born before neonatal screening was introduced (1978 to mid 1981) and a further 60 children born during the first three years of the programme (mid 1981 to 1984), were followed up to the age of 10. The cohorts were compared on measures of clinical outcome, including height, weight, lung function tests, chest x-ray picture and Shwachman score.

RESULTS

Age and sex adjusted standard deviation scores (SDS) for height and weight were consistently higher in children screened for cystic fibrosis than in those born before screening. At 10 years of age, average differences in SDS between groups were 0.4 (95% CI -0.1, 0.8) for weight and 0.3 (95% CI -0.1, 0.7) for height. This translates to an average difference of about 2.7 cm in height and 1.7 kg in weight. Mean FEV1 and FVC (as percentage predicted) were significantly higher in the screened cohort at 5 and 10 years of age, with an average difference of 9.4% FEV1 (95% CI 0.8, 17.9) and 8.4% FVC (95% CI 1.8, 15.0) at 10 years. Chest x-ray scores were not different between the groups at any age, but by 10 years screened patients scored an average 5.3 (95% CI 1.2, 9.4) points higher on the Shwachman score.

CONCLUSION

Although not a randomised trial, this long term observational study indicates that early treatment made possible by neonatal screening may be important in determining subsequent clinical outcomes for children with cystic fibrosis. For countries contemplating the introduction of neonatal screening for cystic fibrosis, its introduction to some areas in a cluster randomised design will permit validation of studies performed to date.

Eosinophilic alveolitis in BAL after lung transplantation

Lung transplantation has become a therapeutic option for patients with end stage lung disease. However, outcome after transplantation is complicated by episodes of rejection and infections. Bronchoalveolar lavage is a valuable tool in monitoring patients after transplantation, since it allows the detection of pathogens. A marker specifically indicating rejection from changes in BAL fluid has not been found yet. Especially changes in differential cell count, like lymphocytosis or an increase in polymorphnuclear granulocytes, are unspecific. The role of high eosinophil levels in BAL has not been elucidated yet. We analyzed 25 BAL samples and clinical data of 4 patients who underwent lung transplantation and presented with recurrent episodes of eosinophilic alveolitis in BAL. All patients demonstrated a deterioration of clinical condition, lung function, and blood gas analysis during times of eosinophilia in BAL, compared to previous examinations. In all cases, eosinophilia in BAL was accompanied by rejection. All patients were finally treated with high doses of steroids, resulting in improvement of all parameters. Eosinophilia was not associated with significant changes in the IL-5 concentration in BAL or the pattern of IL-5 expression in BAL cells. In conclusion, eosinophilic alveolitis may indicate acute rejection in patients after lung transplantation, if other causes of eosinophilia are excluded.

Fasting blood glucose: an underestimated risk factor for cardiovascular death. Results from a 22-year follow-up of healthy nondiabetic men

OBJECTIVE

Because of the available conflicting epidemiological data, we investigated the possible impact of fasting blood glucose as a risk factor for cardiovascular death in nondiabetic men. This study reports the results from a 22-year prospective study on fasting blood glucose as a predictor of cardiovascular death.

RESEARCH DESIGN AND METHODS

Of the 1,998 apparently healthy nondiabetic men (aged 40-59 years), a total of 1,973 with fasting blood glucose < 110 mg/dl were included in the study in which also a number of conventional risk factors were measured at baseline.

RESULTS

After 22 years of follow-up, 483 men had died, 53% from cardiovascular diseases. After dividing men into quartiles of fasting blood glucose level, it was found that men in the highest glucose quartile (fasting blood glucose > 85 mg/dl) had a significantly higher mortality rate from cardiovascular diseases compared with those in the three lowest quartiles. Even after adjusting for age, smoking habits, serum lipids, blood pressure, forced expiratory volume in 1 s, and physical fitness (Cox model), the relative risk of cardiovascular death for men with fasting blood glucose > 85 mg/dl remained 1.4 (95% CI 1.04-1.8). Noncardiovascular deaths were unrelated to fasting blood glucose level.

CONCLUSIONS

Fasting blood glucose values in the upper normal range appears to be an important independent predictor of cardiovascular death in nondiabetic apparently healthy middle-aged men.

Variable extrathoracic airflow obstruction and chronic laryngotracheitis in Gulf War veterans

STUDY OBJECTIVES

To study the flow-volume loop for evidence of variable extrathoracic airflow obstruction in Persian Gulf War veterans.

DESIGN

Retrospective case-control, single-center study.

SETTING

The pulmonary division of an academic health-care center.

SUBJECTS

A convenience sample of the Persian Gulf Registry.

MEASUREMENTS AND INTERVENTIONS

(1) Midvital capacity ratio (ratio of maximum forced midexpiratory to maximum forced midinspiratory flow). This ratio is the criterion standard for the diagnosis of variable extrathoracic airflow obstruction. (2) Evaluation of the anatomy and function of the extrathoracic airway by fiberoptic bronchoscopy. (3) Further investigation into the airway abnormality by histologic evaluation of tracheal biopsy samples in Gulf War veterans only.

RESULTS

Midvital capacity was > 1.0 in 32 of 37 Gulf War veterans compared with only 11 of 38 control subjects. The mean (+/-SD) value was 1.37+/-0.4 among Gulf War veterans and 0.88+/-0.3 among control subjects (p=0.0000005). FVC and its ratio to FEV1 were normal in all these subjects. Bronchoscopy showed inflamed larynx and trachea in all (n=17) Gulf War veterans. Histologic study showed chronic inflammation of the trachea in everyone (n=12) who had an adequate biopsy sample.

CONCLUSION

Physicians should be made aware of the presence of chronic inflammation of the upper airways and inspiratory airflow limitation in a number of Gulf War veterans.