Noninvasive Assessment of Impaired Gas Exchange with the Alveolar Gas Monitor Predicts Clinical Deterioration in COVID-19 Patients

BACKGROUND AND OBJECTIVE

The COVID-19 pandemic magnified the importance of gas exchange abnormalities in early respiratory failure. Pulse oximetry (SpO2) has not been universally effective for clinical decision-making, possibly because of limitations. The alveolar gas monitor (AGM100) adds exhaled gas tensions to SpO2 to calculate the oxygen deficit (OD). The OD parallels the alveolar-to-arterial oxygen difference (AaDO2) in outpatients with cardiopulmonary disease. We hypothesized that the OD would discriminate between COVID-19 patients who require hospital admission and those who are discharged home, as well as predict need for supplemental oxygen during the index hospitalization.

METHODS

Patients presenting with dyspnea and COVID-19 were enrolled with informed consent and had OD measured using the AGM100. The OD was then compared between admitted and discharged patients and between patients who required supplemental oxygen and those who did not. The OD was also compared to SpO2 for each of these outcomes using receiver operating characteristic (ROC) curves.

RESULTS

Thirty patients were COVID-19 positive and had complete AGM100 data. The mean OD was significantly (p = 0.025) higher among those admitted 50.0 ± 20.6 (mean ± SD) vs. discharged 27.0 ± 14.3 (mean ± SD). The OD was also significantly (p < 0.0001) higher among those requiring supplemental oxygen 60.1 ± 12.9 (mean ± SD) vs. those remaining on room air 25.2 ± 11.9 (mean ± SD). ROC curves for the OD demonstrated very good and excellent sensitivity for predicting hospital admission and supplemental oxygen administration, respectively. The OD performed better than an SpO2 threshold of <94%.

CONCLUSIONS

The AGM100 is a novel, noninvasive way of measuring impaired gas exchange for clinically important endpoints in COVID-19.

Development and Validation of an ICU Delirium Playbook for Provider Education

Although delirium detection and prevention practices are recommended in critical care guidelines, there remains a persistent lack of effective delirium education for ICU providers. To address this knowledge-practice gap, we developed an "ICU Delirium Playbook" to educate providers on delirium detection (using the Confusion Assessment Method for the ICU) and prevention.

DESIGN

Building on our previous ICU Delirium Video Series, our interdisciplinary team developed a corresponding quiz to form a digital "ICU Delirium Playbook." Playbook content validity was evaluated by delirium experts, and face validity by an ICU nurse focus group. Additionally, focus group participants completed the quiz before and after video viewing. Remaining focus group concerns were evaluated in semi-structured follow-up interviews.

SETTING

Online validation survey, virtual focus group, and virtual interviews.

SUBJECTS

The validation group included six delirium experts in the fields of critical care, geriatrics, nursing, and ICU education. The face validation group included nine ICU nurses, three of whom participated in the semi-structured feedback interviews.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The 44-question quiz had excellent content validity (average scale-level content validity index [S-CVI] of individual items = 0.99, universal agreement S-CVI = 0.93, agreement κ ≥ 0.75, and clarity p ≥ 0.8). The focus group participants completed the Playbook in an average (sd) time of 53 (14) minutes, demonstrating significant improvements in pre-post quiz scores (74% vs 86%; p = 0.0009). Verbal feedback highlighted the conciseness, utility, and relevance of the Playbook, with all participants agreeing to deploy the digital education module in their ICUs.

CONCLUSIONS

The ICU Delirium Playbook is a novel, first-of-its-kind asynchronous digital education tool aimed to standardize delirium detection and prevention practices. After a rigorous content and face validation process, the Playbook is now available for widespread use.

Nitrogen-based lung clearance index: a valid physiological biomarker for the clinic

Multiple breath washout (MBW) testing is increasingly used as a physiological measurement in the clinic, due in part to the availability of commercial equipment and reference values for MBW indices. Commercial N₂ washout devices are usually based on indirect measurement of N₂ concentration (C_N2), by directly measuring either molar mass and O₂ and CO₂, or molar mass and CO₂. We aim to elucidate the role of two potential pitfalls associated with N₂-MBW testing that could override its physiological content: indirect N₂ measurement and blood-solubility of N₂. We performed MBW in 12 healthy adult subjects using a commercial device (MBW_indirect) with simultaneous direct gas concentration measurements by mass spectrometry (MBW_direct) and compared C_N2 between MBW_direct and MBW_indirect. We also measured argon concentration during the same washouts to verify the maximal effect gas solubility can have on N₂-based functional residual capacity (FRC) and lung clearance index (LCI). Continuous N₂ concentration traces were very similar for MBW_indirect and MBW_direct, resulting in comparable breath-by-breath washout plots of expired concentration and in no significant differences in FRC_N2, LCI_N2, S_cond, and S_acin between the two methods. Argon washouts were slightly slower than N₂ washouts, as expected for a less diffusive and more soluble gas. Finally, comparison between LCI_N2 and LCI_Ar indicates that the maximum impact from blood-tissue represents less than half a LCI unit in normal subjects. In conclusion, we have demonstrated by direct measurement of N₂ and twice as soluble argon, that indirect N₂ measurement can be safely used as a meaningful physiological measurement.NEW & NOTEWORTHY The physiological content of N₂ multibreath washout testing has been questioned due to N₂ indirect measurement accuracy and N₂ blood solubility. With direct measurement of N₂ and twice as soluble argon, we show that these effects are largely outweighed by ease of use.

Noninvasive measurement of pulmonary gas exchange: comparison with data from arterial blood gases

A new noninvasive method was used to measure the impairment of pulmonary gas exchange in 34 patients with lung disease, and the results were compared with the traditional ideal alveolar-arterial Po₂ difference (AaDO₂) calculated from arterial blood gases. The end-tidal Po₂ was measured from the expired gas during steady-state breathing, the arterial Po₂ was derived from a pulse oximeter if the SpO2 was 95% or less, which was the case for 23 patients. The difference between the end-tidal and the calculated Po₂ was defined as the oxygen deficit. Oxygen deficit was 42.7 mmHg (SE 4.0) in this group of patients, much higher than the means previously found in 20 young normal subjects measured under hypoxic conditions (2.0 mmHg, SE 0.8) and 11 older normal subjects (7.5 mmHg, SE 1.6) and emphasizes the sensitivity of the new method for detecting the presence of abnormal gas exchange. The oxygen deficit was correlated with AaDO₂ ( R² 0.72). The arterial Po₂ that was calculated from the noninvasive technique was correlated with the results from the arterial blood gases ( R² 0.76) and with a mean bias of +2.7 mmHg. The Pco₂ was correlated with the results from the arterial blood gases (R² 0.67) with a mean bias of -3.6 mmHg. We conclude that the oxygen deficit as obtained from the noninvasive method is a very sensitive indicator of impaired pulmonary gas exchange. It has the advantage that it can be obtained within a few minutes by having the patient simply breathe through a tube.

Carbon Dioxide Exposure Resulting From Hood Protective Equipment Used in Joint Arthroplasty Surgery

BACKGROUND

To protect both the surgeon and patient during procedures, hooded protection shields are used during joint arthroplasty procedures. Headache, malaise, and dizziness, consistent with increased carbon dioxide (CO₂) exposure, have been anecdotally reported by surgeons using hoods. We hypothesized that increased CO₂ concentrations were causing reported symptoms.

METHODS

Six healthy subjects (4 men) donned hooded protection, fan at the highest setting. Arm cycle ergometry at workloads of 12 and 25 watts (W) simulated workloads encountered during arthroplasty. Inspired O₂ and CO₂ concentrations at the nares were continuously measured at rest, 12 W, and 25 W. At each activity level, the fan was deactivated and the times for CO₂ to reach 0.5% and 1.0% were measured.

RESULTS

At rest, inspired CO₂ was 0.14% ± 0.04%. Exercise had significant effect on CO₂ compared with rest (0.26% ± 0.08% at 12 W, P = .04; 0.31% ± 0.05% at 25 W, P = .003). Inspired CO₂ concentration increased rapidly with fan deactivation, with the time for CO₂ to increase to 0.5% and 1.0% after fan deactivation being rapid but variable (0.5%, 12 ± 9 seconds; 1%, 26 ± 15 seconds). Time for CO₂ to return below 0.5% after fan reactivation was 20 ± 37 seconds.

CONCLUSION

During simulated joint arthroplasty, CO₂ remained within Occupational Safety and Health Administration (OSHA) standards with the fan at the highest setting. With fan deactivation, CO₂ concentration rapidly exceeds OSHA standards.

Total and regional deposition of inhaled aerosols in supine healthy subjects and subjects with mild-to-moderate COPD

Despite substantial development of sophisticated subject-specific computational models of aerosol transport and deposition in human lungs, experimental validation of predictions from these new models is sparse. We collected aerosol retention and exhalation profiles in seven healthy volunteers and six subjects with mild-to-moderate COPD (FEV1 = 50-80%predicted) in the supine posture. Total deposition was measured during continuous breathing of 1 and 2.9 μm-diameter particles (tidal volume of 1 L, flow rate of 0.3 L/s and 0.75 L/s). Bolus inhalations of 1 μm particles were performed to penetration volumes of 200, 500 and 800 mL (flow rate of 0.5 L/s). Aerosol bolus dispersion (H), deposition, and mode shift (MS) were calculated from these data. There was no significant difference in total deposition between healthy subjects and those with COPD. Total deposition increased with increasing particle size and also with increasing flow rate. Similarly, there was no significant difference in aerosol bolus deposition between subject groups. Yet, the rate of increase in dispersion and of decrease in MS with increasing penetration volume was higher in subjects with COPD than in healthy volunteers (H: 0.798 ± 0.205 vs. 0.527 ± 0.122 mL/mL, p=0.01; MS: -0.271±0.129 vs. -0.145 ± 0.076 mL/mL, p=0.05) indicating larger ventilation inhomogeneities (based on H) and increased flow sequencing (based on MS) in the COPD than in the healthy group. In conclusion, in the supine posture, deposition appears to lack sensitivity for assessing the effect of lung morphology and/or ventilation distribution alteration induced by mild-to-moderate lung disease on the fate of inhaled aerosols. However, other parameters such as aerosol bolus dispersion and mode shift may be more sensitive parameters for evaluating models of lungs with moderate disease.

Increased blood-oxygen binding affinity in Tibetan and Han Chinese residents at 4200 m

High-altitude natives are challenged by hypoxia, and a potential compensatory mechanism could be reduced blood oxygen-binding affinity (P50), as seen in several high-altitude mammalian species. In 21 Qinghai Tibetan and nine Han Chinese men, all resident at 4200 m, standard P50 was calculated from measurements of arterial PO2 and forehead oximeter oxygen saturation, which was validated in a separate examination of 13 healthy subjects residing at sea level. In both Tibetans and Han Chinese, standard P50 was 24.5 ± 1.4 and 24.5 ± 2.0 mmHg, respectively, and was lower than in the sea-level subjects (26.2 ± 0.6 mmHg, P < 0.01). There was no relationship between P50 and haemoglobin concentration (the latter ranging from 15.2 to 22.9 g dl(-1) in Tibetans). During peak exercise, P50 was not associated with alveolar-arterial PO2 difference or peak O2 uptake per kilogram. There appears to be no apparent benefit of a lower P50 in this adult high-altitude Tibetan population.

Removal of sedimentation decreases relative deposition of coarse particles in the lung periphery

Lung deposition of >0.5-μm particles is strongly influenced by gravitational sedimentation, with deposition being reduced in microgravity (μG) compared with normal gravity (1G). Gravity not only affects total deposition, but may also alter regional deposition. Using gamma scintigraphy, we measured the distribution of regional deposition and retention of radiolabeled particles ((99m)Tc-labeled sulfur colloid, 5-μm diameter) in five healthy volunteers. Particles were inhaled in a controlled fashion (0.5 l/s, 15 breaths/min) during multiple periods of μG aboard the National Aeronautics and Space Administration Microgravity Research Aircraft and in 1G. In both cases, deposition scans were obtained immediately postinhalation and at 1 h 30 min, 4 h, and 22 h postinhalation. Regional deposition was characterized by the central-to-peripheral ratio and by the skew of the distribution of deposited particles on scans acquired directly postinhalation. Relative distribution of deposition between the airways and the alveolar region was derived from data acquired at the various time points. Compared with inhalation in 1G, subjects show an increase in central-to-peripheral ratio (P = 0.043), skew (P = 0.043), and tracheobronchial deposition (P < 0.001) when particles were inhaled in μG. The absence of gravity caused fewer particles to deposit in the lung periphery than in the central region where deposition occurred mainly in the airways in μG. Furthermore, the increased skew observed in μG likely illustrates the presence of localized areas of deposition, i.e., "hot spots", resulting from inertial impaction. In conclusion, gravity has a significant effect on deposition patterns of coarse particles, with most of deposition occurring in the alveolar region in 1G but in the large airways in μG.

Production and fate of the sea lamprey migratory pheromone

Biochemical studies demonstrate that three steroids postulated to function as the sea lamprey migratory pheromone are released in sufficient quantities, and possess adequate stability and binding characteristics, to function as a multi-component pheromone in natural river waters. Mass spectrometric (MS) analyses of the holding water of recently fed larval lamprey demonstrated that each of these compounds is released at rates of 5-25 ng larva(-1) h(-1), adequate to produce picomolar (biologically relevant) concentrations in river waters. Petromyzonamine disulfate (PSDS) was released at about twice the rate of the other two components, petromyzonamine disulfate (PADS) and petromyzonol sulfate (PS). Unfed larvae also released all three steroids but only at about two-thirds the rate of fed larvae and in a different ratio. However, a behavioral test of fed and unfed larval holding waters suggested this change in pheromone ratio does not diminish pheromonal signal function in the winter when larvae are not feeding. A study of steroid degradation found that PADS and PSDS had half-lives of about 3 days, similar to values previously described for PS and sufficiently slow for the entire pheromone to persist in river mouths. Finally, both MS and electro-olfactogram recording found that contrary to previous suggestions, natural levels of natural organic matter found in streams do not bind to these steroids in ways that diminish their natural biological potency. In conclusion, it appears highly likely that a mixture of PADS, PSDS and PS is present at biologically relevant concentrations and ratios in many Great Lakes streams where it functions as a pheromonal attractant.

Simultaneous occurrence of clinical manifestations of myeloma and Waldenström's macroglobulinemia with monoclonal IgG Lambda and IgM Kappa in a single patient

This paper reports a rare case of a patient with biclonal gammopathy IGM kappa and IgG lambda corresponding to the simultaneous occurrence of the clinical manifestations of Waldenström's macroglobulinemia and multiple myeloma. Two cellular populations derived from the B lymphocyte cell line can be observed in this patient. Bone marrow aspiration revealed abnormal plasma cells with inclusions and lymph node aspiration showed immature lymphoid cells containing mu heavy chains.

Waldenström's macroglobulinemia in monozygotic twins

This paper reports a unique familial occurrence of Waldenström's macroglobulinemia (WM) in monozygotic twins. The determination of twin monozygosity has been performed by electrophoretic and immunological typing of genetic systems (erythrocyte blood groups, leucocyte antigens and serum protein polymorphism). The two monoclonal IgM differ one from the other by their light chain type and their idiotypic determinants. Although a genetic predisposition to WM exists in these twins, the gene recombination leading to idiotypic specificity and light chain assortment occurs independently of the monoclonal malignant involvement.

Vital capacity, respiratory muscle strength, and pulmonary gas exchange during long-duration exposure to microgravity

Extended exposure to microgravity (μG) is known to reduce strength in weight-bearing muscles and was also reported to reduce respiratory muscle strength. Short- duration exposure to μG reduces vital capacity (VC), a surrogate measure for respiratory muscle strength, for the first few days, with little change in O2 uptake, ventilation, or end-tidal partial pressures. Accordingly we measured VC, maximum inspiratory and expiratory pressures, and indexes of pulmonary gas exchange in 10 normal subjects (9 men, 1 woman, 39–52 yr) who lived on the International Space Station for 130–196 days in a normoxic, normobaric atmosphere. Subjects were studied four times in the standing and supine postures preflight at sea level at 1 G, approximately monthly in μG, and multiple times postflight. VC in μG was essentially unchanged compared with preflight standing [5.28 ± 0.08 liters (mean ± SE), n = 187; 5.24 ± 0.09, n = 117, respectively; P = 0.03] and considerably greater than that measured supine in 1G (4.96 ± 0.10, n = 114, P < 0.001). There was a trend for VC to decrease after the first 2 mo of μG, but there were no changes postflight. Maximum respiratory pressures in μG were generally intermediate to those standing and supine in 1G, and importantly they showed no decrease with time spent in μG. O2 uptake and CO2 production were reduced (∼12%) in extended μG, but inhomogeneity in the lung was not different compared with short-duration exposure to μG. The results show that VC is essentially unchanged and respiratory muscle strength is maintained during extended exposure to μG, and metabolic rate is reduced.

Pulmonary gas exchange is not impaired 24 h after extravehicular activity

Extravehicular activity (EVA) during spaceflight involves a significant decompression stress. Previous studies have shown an increase in the inhomogeneity of ventilation-perfusion ratio (VA/Q) after some underwater dives, presumably through the embolic effects of venous gas microemboli in the lung. Ground-based chamber studies simulating EVA have shown that venous gas microemboli occur in a large percentage of the subjects undergoing decompression, despite the use of prebreathe protocols to reduce dissolved N(2) in the tissues. We studied eight crewmembers (7 male, 1 female) of the International Space Station who performed 15 EVAs (initial cabin pressure 748 mmHg, final suit pressure either approximately 295 or approximately 220 mmHg depending on the suit used) and who followed the denitrogenation procedures approved for EVA from the International Space Station. The intrabreath VA/Q slope was calculated from the alveolar Po(2) and Pco(2) in a prolonged exhalation maneuver on the day after EVA and compared with measurements made in microgravity on days well separated from the EVA. There were no significant changes in intrabreath VA/Q slope as a result of EVA, although there was a slight increase in metabolic rate and ventilation (approximately 9%) on the day after EVA. Vital capacity and other measures of pulmonary function were largely unaltered by EVA. Because measurements could only be performed on the day after EVA because of logistical constraints, we were unable to determine an acute effect of EVA on VA/Q inequality. The results suggest that current denitrogenation protocols do not result in any major lasting alteration to gas exchange in the lung.

Effect of 6 degrees head-down tilt on cardiopulmonary function: comparison with microgravity

BACKGROUND

Head-down tilt (HDT) of 6 degrees is a commonly used model of weightlessness, but there are few comparisons with actual microgravity.

HYPOTHESIS

Our study was designed to prove that the changes in cardiopulmonary function seen in HDT would be similar to those seen in microgravity.

METHODS

We compared measurements of cardiovascular and pulmonary function from three separate spaceflights of 14 to 17 d duration, with data collected during a 17-d period of HDT.

RESULTS

HDT proved a good model of the cardiovascular response to microgravity, resulting in increases in cardiac output and stroke volume of a similar magnitude to those seen in microgravity, with a concomitant reduction in heart rate. By contrast, HDT was a poor model of the effects of microgravity on pulmonary ventilation and gas exchange.

CONCLUSION

Pulmonary function in HDT approximated the changes seen in the 1-G supine posture, while in microgravity this was much closer to that seen in the 1-G upright position. The differences probably reflect the fact that changes in cardiovascular function result primarily from fluid shifts within the entire body, whereas changes in pulmonary ventilation are primarily a result of mechanical influences on the lung and chest and abdominal wall.

A statewide initiative to improve the care of hospitalized pneumonia patients: The Connecticut Pneumonia Pathway Project

PURPOSE

A statewide quality improvement initiative was conducted in Connecticut to improve process-of-care performance and to decrease length of stay for patients hospitalized with community-acquired pneumonia.

SETTING AND METHODS

Data were collected on 1,242 elderly (> or =65 years) pneumonia patients hospitalized at 31 of 32 acute care hospitals between January 16, 1995, and March 15, 1996, and on 1,146 patients hospitalized between January 1, 1997, and June 30, 1997. Interventions included feedback of performance data (Qualidigm, the Connecticut Peer Review Organization), dissemination of an evidence-based pneumonia critical pathway (Connecticut Thoracic Society), and sharing of pathway implementation experiences (hospitals). Process and outcome measures included early antibiotic administration, blood culture collection, oxygenation assessment, length of stay, 30-day mortality, and 30-day readmission rates. Analyses were adjusted for severity of illness and hospital-specific practice patterns.

RESULTS

After the statewide initiative, improvements were noted in antibiotic administration within 8 hours of hospital arrival (improvement from 83.4% to 88.8%, relative risk [RR] = 1.21; 95% confidence interval [CI]: 1.10 to 1.32), oxygenation assessment within 24 hours of hospital arrival (93.6% to 95.4%; RR = 1.23, 95% CI: 1.11 to 1.38), and length of stay (7 days to 5 days, P <0.001). There were no significant changes in blood culture collection within 24 hours of hospital arrival, blood culture collection before antibiotic administration, 30-day mortality, or 30-day readmission rates.

CONCLUSIONS

Statewide improvements were demonstrated in the care of hospitalized pneumonia patients concurrent with a multifaceted quality improvement intervention. Further research is needed to separate the effects of the quality improvement interventions from secular trends.

Characterization of clinical tolerance to inhaled zinc oxide in naive subjects and sheet metal workers

Clinical tolerance to the acute effects of zinc oxide inhalation develops in workers during periods of repeated exposure. The aims of this study were to determine whether clinical tolerance is accompanied by a reduction in the acute pulmonary inflammatory and cytokine responses to zinc oxide exposure and whether tolerance can be demonstrated in sheet metal workers who chronically inhale low levels of zinc oxide. Naive (never-exposed) subjects inhaled 5 mg/m3 zinc oxide on 1 or 3 days and underwent bronchoalveolar lavage 20 hours after the final exposure. Sheet metal workers inhaled zinc oxide on 1 day and control furnace gas on another day. Among naive subjects in whom tolerance was induced, bronchoalveolar lavage fluid percent neutrophils and interleukin-6 (IL-6) levels were significantly decreased compared with subjects who underwent only a single exposure. Sheet metal workers were much less symptomatic, but they still experienced a significant increase in plasma IL-6. The results indicate that clinical tolerance to zinc oxide is accompanied by reduced pulmonary inflammation and that chronically exposed sheet metal workers are not clinically affected by exposure to zinc oxide fume at the Occupational Safety and Health Administration Permissible Exposure Limit. The increase in IL-6 levels observed in the clinically responsive, and to a lesser extent, tolerant, states following zinc oxide inhalation is consistent with the dual role of IL-6 as a pyrogen and anti-inflammatory agent.

Associations between initial antimicrobial therapy and medical outcomes for hospitalized elderly patients with pneumonia

BACKGROUND

Although medical practice guidelines exist, there have been no large-scale studies assessing the relationship between initial antimicrobial therapy and medical outcomes for patients hospitalized with pneumonia.

OBJECTIVE

To determine the associations between initial antimicrobial therapy and 30-day mortality for these patients.

METHODS

Hospital records for 12945 Medicare inpatients (> or = 65 years of age) with pneumonia were reviewed. Associations between initial antimicrobial regimens and 30-day mortality were assessed with Cox proportional hazards models, adjusting for baseline differences in patient characteristics, illness severity, and processes of care. Comparisons were made with patients treated with a non-pseudomonal third-generation cephalosporin alone (the reference group).

RESULTS

Initial treatment with a second-generation cephalosporin plus macrolide (hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.52-0.96), a non-pseudomonal third-generation cephalosporin plus macrolide (HR, 0.74; 95% CI, 0.60-0.92), or a fluoroquinolone alone (HR, 0.64; 95% CI, 0.43-0.94) was independently associated with lower 30-day mortality. Adjusted mortality among patients initially treated with these 3 regimens became significantly lower than that in the reference group beginning 2, 3, and 7 days, respectively, after hospital admission. Use of a beta-lactam/beta-lactamase inhibitor plus macrolide (HR, 1.77; 95% CI, 1.28-2.46) and an aminoglycoside plus another agent (HR, 1.21; 95% CI, 1.02-1.43) were associated with an increased 30-day mortality.

CONCLUSIONS

In this study of primarily community-dwelling elderly patients hospitalized with pneumonia, 3 initial empiric antimicrobial regimens were independently associated with a lower 30-day mortality. The more widespread use of these antimicrobial regimens is likely to improve the medical outcomes for elderly patients with pneumonia.

Factors inhibiting use of the pneumococcal polysaccharide vaccine: a survey of Connecticut physicians

BACKGROUND

The pneumococcal polysaccharide vaccine (PPV) is effective in preventing invasive pneumococcal disease, but remains underutilized. Prior surveys of physicians revealed concern regarding the safety and efficacy of the vaccine, but there has been little information published in the last 10 years that sheds light on why the vaccine remains underutilized. Although there is currently emphasis on providing PPV to hospitalized patients, there is even less known about what factors prevent PPV use in the hospital setting and chronic care setting. We performed a survey of physicians in Connecticut to determine what factors prevent utilization of the vaccine in three patient care settings.

METHODS

A survey of internists and family practitioners in Connecticut that ascertained their frequency of utilization of PPV and what factors inhibited utilization of PPV.

RESULTS

Three hundred ninety-seven responses are included in the analysis. Forgetting to administer the vaccine (59% of respondents) and patient refusal (55% of respondents) were the factors most frequently noted as being important in preventing vaccination in the outpatient setting. In the inpatient and chronic care settings, difficulty in determining the patient's vaccine status was also noted. Concerns regarding the efficacy or safety of the vaccine did not seem to be important. The factor that correlated most closely with the respondents' reported frequency of vaccine use was forgetting to vaccinate.

CONCLUSIONS

Physicians, although accepting the efficacy of PPV, are inhibited from its more frequent use by several factors.

Quality of care, process, and outcomes in elderly patients with pneumonia

CONTEXT

Pneumonia is a frequent cause of hospitalization and death among elderly patients, but the relationships between processes of care for pneumonia and outcomes are uncertain, making quality improvement a challenge.

OBJECTIVES

To assess quality of care for Medicare patients hospitalized with pneumonia and to determine whether process of care performance is associated with lower 30-day mortality.

DESIGN

Multicenter retrospective cohort study with medical record review.

SETTING

A total of 3555 acute care hospitals throughout the United States.

PATIENTS

A total of 14069 patients at least 65 years old hospitalized with pneumonia.

MAIN OUTCOME MEASURES

Four processes of care: time from hospital arrival to initial antibiotic administration; blood culture collection before initial hospital antibiotics; blood culture collection within 24 hours of hospital arrival; and oxygenation assessment within 24 hours of hospital arrival. Associations between processes of care and 30-day mortality were determined with logistic regression analysis.

RESULTS

National estimates of process-of-care performance were antibiotic administration within 8 hours of hospital arrival, 75.5% (95% confidence interval [CI], 73.1-77.9); blood cultures before antibiotics, 57.3% (95% CI, 54.5-60.1); initial blood culture collection, 68.7% (95% CI, 66.2-71.2); and initial oxygenation assessment, 89.3% (95% CI, 87.5-90.9). Lower 30-day mortality was associated with antibiotic administration within 8 hours of hospital arrival (odds ratio [OR], 0.85; 95% CI, 0.75-0.96) and blood culture collection within 24 hours of arrival (OR, 0.90; 95% CI, 0.81-1.00). State and territory performance estimates varied from 49.0% to 89.7% for antibiotics given within 8 hours and from 45.6% to 82.6% for blood cultures drawn within 24 hours.

CONCLUSIONS

Administering antibiotics within 8 hours of hospital arrival and collecting blood cultures within 24 hours were associated with improved survival. The fact that states varied widely in the performance of these measures suggests that opportunities exist to improve hospital care of elderly patients with pneumonia.

Metal fume fever: characterization of clinical and plasma IL-6 responses in controlled human exposures to zinc oxide fume at and below the threshold limit value

Results from animal and preliminary human exposure studies have called into question whether the 5 mg/m3 8-hour time-weighted average threshold limit value (TLV) for zinc oxide fume is sufficient to protect workers against metal fume fever. The objectives of this study were to determine the clinical effects of exposures to low concentrations of zinc oxide and to ascertain whether these exposures elevated circulating levels of specific cytokines, which could account for the symptoms of the metal fume fever syndrome. Thirteen resting naive subjects inhaled, on separate days, air and 2.5 and 5 mg/m3 of furnace-generated zinc oxide fume for 2 hours. Subjects recorded symptoms and temperature and had blood drawn before and after each exposure. The mean (+/- SE) maximum rise in oral temperature at 6 to 12 hours after exposure was 1.4 +/- 0.3 degrees F after 5 mg/m3, compared with 0.6 +/- 0.5 degrees F after air exposure (P < 0.05). Mean temperature was also elevated after exposure to 2.5 mg/m3 zinc oxide (1.2 +/- 0.3 degrees F). In a parallel fashion, plasma levels of interleukin 6 (IL-6), a pyrogen, were significantly elevated after exposure to 5 mg/m3 zinc oxide. Mean IL-6 values (pg/mL) at pre-exposure and at 3 and 6 hours post-exposure were 1.9 (+/- 0.6), 2.8 (+/- 0.7), and 2.9 (+/- 0.6), respectively, on the air day and 1.6 (+/- 0.6), 4.4 (+/- 1.2), and 6.4 (+/- 1.1) on the 5 mg/m3 zinc oxide day. Zinc oxide exposure did not significantly affect plasma levels of tumor necrosis factor. Total symptom scores peaked 9 hours after the 5 mg/m3 zinc oxide exposure. Myalgias, cough, and fatigue were the predominant symptoms reported. Inhalation of zinc oxide for 2 hours at the current TLV of 5 mg/m3 produces fever and symptoms along with elevation in plasma IL-6 levels.

Summertime haze air pollution and children with asthma

In order to investigate associations between summertime haze air pollution and asthma at an individual level, 52, 58, and 56 children (ages 7 to 13) attending a summer "asthma camp" were followed during the last week of June in 1991, 1992, and 1993, respectively. Most of the subjects had moderate to severe asthma. Daily records were kept of the environmental conditions, as well as of subject medication use, lung function, and medical symptoms. Air pollution was found to be significantly and consistently correlated with acute asthma exacerbations, chest symptoms, and lung function decrements. The pollutant most consistently associated with adverse health consequences was ozone (O3), although associations with sulfates and hydrogen ion suggest a possible role by fine particles as well. Effects were found to be roughly monotonic as a function of O3 concentration. Regression of morning (8:00 A.M.) to afternoon (5:00 P.M.) peak flow change on O3 indicated pulmonary function reductions similar to those previously reported for more active children without asthma. Moreover, analyses also indicated an increased risk of an asthma exacerbation and of experiencing chest symptoms of approximately 40% on the highest pollution day, relative to the mean. Based on these relative risk estimates, a rise in the 1-h daily maximal O3 from 84 ppb to 160 ppb was associated in this group with an increase from 20 to 28 (+/- 2) in the expected number of unscheduled medications administered/day, and from 29 to 41 (+/- 3) in the expected total number of chest symptoms/day. Thus, air pollution can be a major contributor to the respiratory problems experienced by children with asthma during the summer months.

Recombinant human DNase in management of lobar atelectasis due to retained secretions

Recombinant human deoxyribonuclease (rhDNase) is an agent which reduces the viscoelasticity of purulent sputum. Two cases are reported in which rhDNase was utilised for the management of lobar atelectasis due to retained purulent secretions.

Sodium depletion prevents albuminuria in hypertensive rats

The effect of short term (8 weeks) sodium (Na+) depletion and its repletion on glomerular synthesis of heparan sulfate and urinary excretions of albumin, total protein, heparan sulfate, Na+ and potassium (K+) was studied in spontaneous hypertensive rats (SHR) and their control normotensive Wistar-Kyoto rats (WKY). Na+ depletion in SHRs significantly increased the synthesis of glomerular heparan sulfate and decreased urinary excretions of albumin, Na+ and heparan sulfate when compared with the Na+ repleted group. In WKY rats, Na+ depletion did not cause any of the above changes. These data suggest that Na+ depletion prevents the urinary loss of protein through preservation of glomerular heparan sulfate only in SHRs.

Alteration of pulmonary macrophage intracellular pH regulation by sulfuric acid aerosol exposures

In vivo exposure to sulfuric acid aerosols produces profound effects on pulmonary macrophage (PM phi) phagocytic function and cytokine release and perturbs intracellular pH (pHi) homeostasis. Because pHi influences a multitude of cellular processes, we sought to investigate the mechanism by which acid aerosol exposure affects its regulation. Guinea pigs underwent a single or 5 repeated 3-hr exposures to sulfuric acid aerosol (969 and 974 micrograms/m3 for single and repeated exposures, respectively). PM phi harvested immediately after exposure were incubated in HCO3-free media and their pHi recovery from an intracellular acid load was examined. The overall pHi recovery was depressed after single and multiple exposures to sulfuric acid aerosol. delta pHi (the difference between initial pHi and the one measured at 150 sec) decreased by 15.6 and 23.3% (p < 0.05) for single and repeated exposures, respectively. Initial dpHi/dt (maximum pHi recovery rate) after cytoplasmic acidification diminished by 20.3 and 32.2%, which were not statistically significant (p = 0.08 for repeated exposure). To determine whether the activity of the H(+)-ATPase pump the Na(+)-H+ exchanger was specifically altered by the acid exposures, PM phi were first incubated in Na+ and HCO3-free media with NBD-Cl (7-chloro-4-nitrobenz-2-oxa-1,3-diazol, blocking H(+)-ATPase and leaving only the Na(+)-H+ exchanger in effect) and then challenged with 30 mM NaCl. The pHi recovery of PM phi after Na challenge was significantly reduced in acid aerosol exposed guinea pigs (p < 0.05) compared to controls (for delta pHi, 18.2% lower in single exposure and 22.7% in multiple exposure groups; for initial dpHi/dt, 26.9% lower in single exposure and 22.4% in multiple exposure groups). In contrast, the H(+)-ATPase pump was inconsistently affected as indicated by delta pHi and initial dpHi/dt measured in the presence of MIA (amiloride-5-N-methylisobutyl, inhibiting the Na(+)-H+ exchanger and leaving only the H(+)-ATPase pump in effect). These results suggest that in vivo exposure to sulfuric acid aerosols induces alterations in pHi regulation in guinea pig PM phi attributable to changes in Na(+)-H+ exchanger activity.

Metal fume fever

Metal fume fever is an acute self-limited illness induced most commonly by inhalation of zinc oxide fumes. The affected individual characteristically experiences the rapid onset of intense shaking chills, fever, and body aches a few hours after exposure, and symptoms dissipate spontaneously. While the occurrence of metal fume fever appears to be widespread and the current TLV/PEL of 5 mg/m3 and STEL of 10 mg/m3 may not be fully protective, no chronic health sequelae have been documented to date. Nonetheless, as any worker who has experienced a full-blown case will likely testify, metal fume fever remains one of the more noxious short-term illnesses contracted in the workplace, and its prevention deserves serious attention.

A novel system for the in vitro exposure of pulmonary cells to acid sulfate aerosols

While ambient acid aerosols are considered a potential respiratory health hazard, the mechanism by which they induce responses in the lungs is not known. Attempts to ascertain these mechanisms using inhalation exposures are complicated by a number of technical difficulties, chief among which are neutralization of inhaled acids by endogenous ammonia and variations in deposition with inhaled particle size. To control for these variables, a novel in vitro exposure system allowing experimental evaluation of factors which influence biologic responses to acid sulfate particles was developed. The system consists of two subunits, a generation/delivery component and a cell exposure component. Sulfuric acid aerosols are generated by nebulizing dilute acid solutions. Particles larger than a specified size of interest (based upon the specific exposure conditions desired) are removed, and particles at the desired size and mass concentration are uniformly delivered onto a target cell monolayer. The system is capable of delivering acid particles larger than 0.7 micron (mass median diameter), yet at constant particle mass concentrations. This paper describes the design of the exposure system and its performance characteristics and presents initial results of some biological responses obtained using it. In conjunction with inhalation studies, this exposure system may provide additional insights into mechanisms by which acid aerosols adversely affect the respiratory tract and into the physical characteristics of acid particles which modulate toxicity.

Interspecies differences in the phagocytic activity of pulmonary macrophages subjected to acidic challenge

Examining interspecies differences in response to ambient pollutants is an essential component of risk assessment. The potential hazard to public health from the inhalation of acid sulfate aerosols is of current concern. A significant biological target is the pulmonary macrophage, which provides a primary defense of the respiratory region of the lungs. One essential function of these cells is phagocytosis of particles. This study assessed the effects of acidic environments on the phagocytic activity of pulmonary macrophages obtained by lavage from humans and three species of laboratory animals commonly used in acid aerosol toxicology studies, namely, rats, rabbits, and guinea pigs. Cells were incubated with polystyrene latex particles in media acidified by addition of sulfuric acid. The percentage of cells which were phagocytic, as well as the relative number of particles ingested by these cells, was found to decrease with increasing acidity for all species. The ranking of response in order of decreasing sensitivity to acidic challenge was as follows: guinea pig > rat > rabbit > human.

Pulmonary effects of inhaled zinc oxide in human subjects, guinea pigs, rats, and rabbits

Occupational exposure to freshly formed zinc oxide (ZnO) particles (less than 1.0 micron aerodynamic diameter) produces a well-characterized response known as metal fume fever. An 8-hr threshold limit value (TLV) of 5 mg/m3 has been established to prevent adverse health effects because of exposure to ZnO fumes. Because animal toxicity studies have demonstrated pulmonary effects near the current TLV, the present study examined the time course and dose-response of the pulmonary injury produced by inhaled ZnO in guinea pigs, rats, rabbits, and human volunteers. The test animals were exposed to 0, 2.5, or 5.0 mg/m3 ZnO for up to 3 hr and their lungs lavaged. Both the lavage fluid and recovered cells were examined for evidence of inflammation or altered cell function. The lavage fluid from guinea pigs and rats exposed to 5 mg/m3 had significant increases in total cells, lactate dehydrogenase, beta-glucuronidase, and protein content. These changes were greatest 24 hr after exposure. Guinea pig alveolar macrophage function was depressed as evidenced by in vitro phagocytosis of opsonized latex beads. Significant changes in lavage fluid parameters were also observed in guinea pigs and rats exposed to 2.5 mg/m3 ZnO. In contrast, rabbits showed no increase in biochemical or cellular parameters following a 2-hr exposure to 5 mg/m3 ZnO. Differences in total lung burden of ZnO, as determined in additional animals by atomic absorption spectroscopy, appeared to account for the observed differences in species responses. Although the lungs of guinea pigs and rats retained approximately 20% and 12% of the inhaled dose, respectively, rabbits retained only 5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of fine and ultrafine sulfuric acid aerosols in guinea pigs: alterations in alveolar macrophage function and intracellular pH

Acidic sulfate is the most toxicologically important sulfur oxide which exists in the ambient air. To determine if particle size influences toxic effects of sulfuric acid, we investigated the effects of sulfuric acid aerosols of two different sizes on biochemical and cellular parameters of bronchoalveolar lavage fluid from exposed guinea pigs. Guinea pigs were exposed to fine (mass median diameter, 0.3 micron), and ultrafine (mass median diameter, 0.04 micron) sulfuric acid aerosols at 300 micrograms/m3 for 3 hr/day. The animals were euthanized immediately and 24 hr after 1 and 4 days of exposure and lungs were lavaged. Elevated beta-glucuronidase, lactate dehydrogenase activities, and total protein concentration as well as decreased cell viability were observed in the lavage after a single exposure to sulfuric acid aerosols of both sizes. These alterations were small, though statistically significant, and transient. No alteration in these parameters was observed after 4 days of exposure to acid aerosols. In contrast, sulfuric acid-induced alterations in alveolar macrophage function were more pronounced and longer lasting. Immediately after a single exposure to fine acid, there was a 2.7-fold increase in the spontaneous tumor necrosis factor (TNF) release over that in the control group while endotoxin-stimulated TNF release was increased by 2.2-fold. In addition, acid aerosols of both sizes increased the TNF release from macrophages after 4 days of exposure, although there was no clear temporal pattern of induction or recovery. Furthermore, immediately after 4 days of exposure to either fine or ultrafine acid, the amount of H2O2 that could be induced from baseline production by alveolar macrophages was 2.2-fold higher than that of the controls. The phagocytic function of macrophages was also altered by exposure to sulfuric acid aerosols. Twenty-four hours after single or multiple exposure, fine acid enhanced (as high as 78% above control) the in vitro phagocytic activity of alveolar macrophages while ultrafine acid depressed the phagocytic capacity (as much as 50% below that in the control). In addition to these biochemical parameters and cellular functions, we also measured the intracellular pH (pHi) of macrophages harvested after exposures to these acid aerosols using a pH-sensitive fluorescent dye. The resting pHi was depressed after a single exposure to both acid aerosols. The depression in pHi persisted 24 hr after ultrafine acid exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Albumin Paris 2: a new genetic variant distinguished by isoelectric focusing

Until recently, the characterization of genetic variants of human serum albumin was performed by electrophoretic typing prior to the determination of their amino acid substitutions. We describe a procedure using isoelectric focusing in the presence of urea for the analysis of the genetic variation of albumin. This procedure allowed a clear distinction of a new variant, previously found to be identical with albumin Sondrio according to its relative electrophoretic mobilities at 3 pHs. This new variant, the third rare albumin allotype identified in the Ile-de-France region, was called albumin Paris 2.

Sarcoidosis complicated by HIV infection: three case reports and a review of the literature

We report three cases of sarcoidosis complicated by human immunodeficiency virus (HIV) infection and review four other isolated case reports in the literature. There is clinical overlap of both diseases, including symptoms, pulmonary function abnormalities, and lymphocyte function. Bronchoalveolar lavage (BAL) in these patients showed a lymphocytic alveolitis without pathogens. BAL lymphocyte subset analysis showed markedly depressed CD4+/CD8+ ratios in three patients. These data were clinically useful for distinguishing the CD8+ alveolitis associated with HIV infection from the CD4+ alveolitis associated with sarcoidosis. Three patients improved with corticosteroid therapy. Two patients with BAL-documented CD8+ alveolitis tolerated discontinuation of steroids. One patient's sarcoidosis improved without therapy concurrent with the diagnosis of Kaposi's sarcoma. Another patient developed sarcoidosis 1 yr after manifesting HIV positive serology. BAL can be used to distinguish the lymphocytic alveolitis of sarcoidosis from that associated with HIV infection. Patients with active sarcoidosis complicated by HIV infection can be effectively treated with corticosteroid therapy.

ABO-blood-group-related idiotypic network: mimicry of oligosaccharide epitope by rabbit antiidiotypic antibodies to murine monoclonal anti-A antibody

The idiotypy of antibodies (Ab) specific for oligosaccharide determinants of blood groups of the human ABO system was studied through a cascade. Xenogenic antiidiotypic Ab (Ab2) raised in rabbits to the murine monoclonal anti-A61 (Ab1) were screened for reactivity with various anti-ABH Ab. Three anti-A and three anti-A,B monoclonal antibodies (mAb) which were developed in the same mouse strain as that producing Ab1, as well as a human polyclonal anti-A, were found to share cross-reactive idiotopes (CRI) with Ab1. CRI on murine mAb could be due to a Biozzi recurrent Id on anti-A Ab reacting with anti-Id "à la Oudin", while CRI on human anti-A Ab suggested the presence of paratope-induced anti-Id. Inhibition by Ab2 of haemagglutination of A, B or O human red blood cells by many murine anti-ABH mAb, and by polyclonal or monoclonal human anti-A, strongly supported the occurrence of anti-Id mimicking ABH epitopes belonging to type 2 determinants carried by human erythrocytes. Furthermore, a rabbit immunized with Ab2 produced a potent Ab3 response characterized by anti-H-type-2 specificity. Altogether, these results are consistent with the first successful production of anti-Id Ab that mimics the tridimensional shape of a well defined and strictly carbohydrate epitope, eliciting a haemagglutinating Ab3.

[Detection and quantification of weak concentrations of antigens using a sensitive and direct method of demonstrating immunoprecipitation reactions]

Using agarose gel coated on GelBond film sheets, and using Coomassie blue stain followed by silver stain, a sensitive microassay has been developed for detecting small amounts of antigen-antibody precipitates, and for quantitating low concentrations of antigen. In order to obtain a high sensitivity, antigen-antibody ratios were adjusted imperatively close to the equivalence in double-diffusion, and for quantitative estimation, single radial immunodiffusion was performed, according to Mancini, by measuring circles at the end point. The use of a double staining procedure allows to detect as little as 8 micrograms/ml antigen by Ouchterlony and 200 ng/ml by Mancini technique. The sensitivity of the method is 100 times greater than classical techniques and other advantages such as the need for minimal amounts of unconcentrated samples, the absence of radioactive labelling, and the absence of interference due to a second or a third antibody coat, make this assay useful for analyzing and quantitating monoclonal antibodies obtained by hybridoma or B-cell immortalization.

A sensitive double-diffusion microassay suitable for the detection of idiotype-antiidiotype precipitates

Using agarose gel coated on GelBond film sheets and using Coomassie blue stain followed by silver stain, a sensitive double-diffusion microassay has been developed for detecting small amounts of precipitate forming during idiotype-antiidiotype reactions. The sensitivity of the method is 10-100 times greater than classical immunodiffusion tests. Other advantages include the need for minimal amounts of unconcentrated sample, the absence of radioactive or toxic substrates, no interference due to a second or third antibody coat such as are used in immunoenzymatic techniques, and the possibility of a direct evaluation of qualitative data such as identity, cross-reactivity or non-identity. As little as 40 ng antibody could be detected, corresponding to an antibody concentration of 8 micrograms/ml, making the microassay useful for rapid screening of idiotype-antiidiotype precipitates during routine analysis of hybridoma supernatants.

Potential bronchoconstrictor stimuli in acid fog

Acid fog is complex and contains multiple stimuli that may be capable of inducing bronchoconstriction. These stimuli include sulfuric and niric acids, the principal inorganic acids present; sulfites, formed in the atmosphere as a reaction product of sulfur dioxide and water droplets; fog water itself, a hypoosmolar aerosol; the organic acid hydroxymethanesulfonate, the bisulfite adduct of formaldehyde; and gaseous pollutants, e.g., sulfur dioxide, oxides of nitrogen, ozone. Given this complexity, evaluation of the respiratory health effects of naturally occurring acid fog requires assessment of the bronchoconstrictor potency of each component stimulus and possible interactions among these stimuli. We summarize the results of three studies that involve characterization of the bronchoconstrictor potency of acid fog stimuli and/or their interaction in subjects with asthma. The results of the first study indicate that titratable acidity appears to be a more important stimulus to bronchoconstriction than is pH. The results of the second study demonstrate that sulfite species are capable of inducing bronchoconstriction, especially when inhaled at acid pH. The results of the third study suggest that acidity can potentiate hypoosmolar fog-induced bronchoconstriction.

Epithelium removal alters responsiveness of guinea pig trachea to substance P

Removal of epithelium from mammalian tracheae has been shown to enhance responsiveness to a variety of contractile and relaxant agents. One of the most dramatic shifts reported has been for guinea pig tracheal tissue denuded of epithelium and treated with substance P. We investigated whether this shift in responsiveness was because of 1) removal of an epithelium-associated enzyme, neutral endopeptidase, which degrades substance P and 2) loss of an epithelium-derived noncyclooxygenase relaxant factor. Using a muscle bath preparation we performed concentration-response curves with substance P and acetylcholine on indomethacin-treated tissues with and without intact epithelium and with and without pretreatment with the neutral endopeptidase inhibitor, phosphoramidon. Epithelium removal potentiated the mean agonist concentration calculated to causes 30% of the maximal contractile response by 148-fold for substance P and by 7-fold for acetylcholine. Phosphoramidon potentiated the contractile response to substance P, but not to acetylcholine, by both the epithelium-intact and denuded tissues (P less than 0.05). However, the degree of enhancement by phosphoramidon was much greater in the intact tissues. With phosphoramidon treatment, therefore, the difference in responsiveness to substance P between the intact and denuded tissues was reduced from 148-fold to 18-fold. This effect of phosphoramidon suggests that the hyperresponsiveness to substance P of epithelium-denuded airway tissue is largely because of removal of neutral endopeptidase. Because all tissues were treated with indomethacin, the leftward shifts in substance P and in acetylcholine responsiveness induced by epithelium removal further suggest that an epithelium-derived noncyclooxygenase factor other than neutral endopeptidase also modulates the contractile response to substance P and to acetylcholine.

Airway inflammation and occupational asthma

Airway inflammation due to exposure to a wide variety of agents encountered in the workplace is a major cause of occupational asthma. This article reviews major examples of occupational asthma linked to airway inflammation, including their epidemiology, pathophysiology, and clinical course.

[Genetic variants of human albumin: structural characterization of allotypes used as references for electrophoretic classification]

Eight different types of genetic variants of albumin are observed in the French population. The analysis of electrophoretic patterns of sera containing these variants, performed a three different pHs (8.6, 5.0 and 6.9) after addition of a reference protein (transferrin), allows the identification each variant by a quantitative estimation of its relative mobilities. The accuracy and reproducibility of the technique make it a useful reference method, commonly employed for studying European variants. The samples used as references for five genetic variant types, proalbumins Christchurch and Lille, albumins Vanves, B and Reading, were subjected to sequence analysis to determine the nature and localization of their structural change. Together with the mutations of albumins Gent and Roma previously described, the data presented here make available seven reference specimens for which the structural changes are characterized out of the eight variants known to exist in France.

Acidity potentiates bronchoconstriction induced by hypoosmolar aerosols

Naturally occurring fogs are usually hypoosmolar with respect to body fluids and can be quite acidic. Because both hypoosmolarity and acidity can cause bronchoconstriction, we studied whether there was a positive interaction between these stimuli in 12 subjects with asthma. We administered the following aerosols: hypoosmolar saline (30 mOsm) at pH 5.5, 3 hypoosmolar acids (0.005 M H2SO4, 0.01 M HNO3 and a 1:1 mixture of 0.005 M H2SO4 and 0.01 M HNO3, all 30 mOsm) at pH 2, and isoosmolar 0.005 M H2SO4 (300 mOsm) at pH 2. Each aerosol was administered on a separate day and was inhaled through a mouthpiece during tidal breathing. Specific airway resistance (SRaw) was measured before and after the subjects inhaled aerosols delivered at as much as 5 doubling nebulizer outputs. For each aerosol challenge, an output-response curve was generated, and the nebulizer output required to increase SRaw by 100% above baseline (PO100) was calculated. Mean values of PO100 were significantly lower for each of the hypoosmolar acids than for hypoosmolar saline (1.65 + 0.43 g/min [mean + SEM] for saline compared with 0.95 + 0.11, 1.05 + 0.20, and 0.90 + 0.14 for H2SO4, HNO3, and a 1:1 mixture of the two; all p values less than 0.025). Mean values of PO100 did not differ among the 3 acids studied. For 7 of 12 subjects, all 3 acids caused a leftward shift in the output-response curve from the curve generated for hypoosmolar saline aerosol. Isoosmolar H2SO4 did not increase SRaw by 100% in any subjects, even at the maximal nebulizer output that delivered a concentration of H2SO4 in excess of 40 mg/m3.(ABSTRACT TRUNCATED AT 250 WORDS)