Respiratory Care

Handheld spirometers have several advantages over desktop spirometers, but worries persist regarding reproducibility and validity of data from handheld spirometers. We undertook an independent examination of the EasyOne handheld spirometer.

The laboratory testing included reproducibility and validity testing with a waveform generator. We used standard American Thoracic Society waveforms for in-line testing, calibration adaptor testing, and testing during compression of the mouthpiece. The clinical testing involved repeated tests with 24 spirometry-naïve volunteers and comparison to spirometry results from laboratory (volume-sensing dry rolling seal) spirometer.

The EasyOne exceeded standard thresholds for acceptability with the American Thoracic Society waveforms. In-line testing yielded valid results from the EasyOne. Between the EasyOne and the reference spirometer readings the mean ± SD difference was 0.03 ± 0.23 L for forced vital capacity (FVC) and −0.06 ± 0.09 L for forced expiratory volume in the first second (FEV₁). The calibration adaptor showed no appreciable problems. Extreme compression of the mouthpiece reduced the measured values. In clinical testing the coefficients of variation and limits of agreement were, respectively, 3.3% and 0.24 L for FVC, 2.6% and 0.18 L for FEV₁, and 1.9% and 0.05 for the FEV₁/FVC ratio. The EasyOne readings were lower than those from the reference spirometer; the differences were: −0.12 L for FVC, −0.17 L for FEV₁, and −0.02 for FEV₁/FVC. The limits of agreement were within criteria for FVC but not for the FEV₁, possibly due to a training effect.

The EasyOne spirometer yielded generally reproducible results that were generally valid, compared to the values from the laboratory spirometer. The use of the EasyOne in clinical, occupational, and research settings seems justified.

Malnutrition might be expected to result in reduced maximum respiratory pressure and pulmonary function in cystic fibrosis (CF).

To assess the relationship between nutritional status and maximum respiratory pressures in patients with CF.

We performed a prospective cross-sectional study of patients ≥ 16 y old attending the Adult CF Program at Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil. Maximum inspiratory and expiratory pressures (MIP and MEP) were measured as indexes of respiratory muscle strength. Nutritional status was assessed via body mass index (BMI), triceps-skin-fold thickness and mid-upper-arm-muscle circumference. The patients were classified into 2 groups according to BMI: normal and nutritional depletion. Spirometry was performed by all subjects.

The study included 39 patients (23 female/16 male) with a mean age of 23.7 ± 6.4 y. The mean ± SD percent-of-predicted MIP was 88.0 ± 28.5% in the normal group and 83.2 ± 27.3% in the nutritional-depletion group (p = 0.605). The mean ± SD percent-of-predicted MEP was 84.7 ± 24.2% in the normal group and 86.1 ± 26.3% in the nutritional-depletion group (p = 0.874). The mean ± SD percent-of-predicted forced expiratory volume in the first second (FEV₁) was 55.2 ± 27.5% in the normal group and 50.0 ± 25.6% in the nutritional-depletion group (p = 0.568). MEP and MIP had no significant correlation to BMI or FEV₁.

MEP and MIP had no significant relationship to nutritional status, clinical score, chest radiograph score, and pulmonary function.

Respiratory infections with sputum production are a major reason for physician visits, diagnostic testing, and antibiotic prescription in the United States. We sought to determine whether the simple characteristic of sputum color provides information that impacts resource utilization such as laboratory testing and prescription of antibiotics.

Out-patient sputum samples submitted to the microbiology laboratory for routine analysis were assigned to one of 8 color categories (green, yellow-green, rust, yellow, red, cream, white, and clear), based on a key made from paint chip color samples. Subsequent Gram stain and culture results were compared to sputum color.

Of 289 consecutive samples, 144 (50%) met standard Gram-stain criteria for being acceptable lower-respiratory-tract specimens. In the acceptable Gram-stain group, 60 samples had a predominant organism on Gram stain, and the culture yielded a consistent result in 42 samples (15% of the 289 total specimens). Yield at each level of analysis differed greatly by color. The yield from sputum colors green, yellow-green, yellow, and rust was much higher than the yield from cream, white, or clear.

If out-patient sputum is cream, white, or clear, the yield from bacteriologic analysis is extremely low. This information can reduce laboratory processing costs and help minimize unnecessary antibiotic prescription.

Physicians often fail to use lung-protective ventilation (LPV) in patients with acute lung injury.

To use physician documentation to identify why physicians did not initiate or continue LPV in patients with acute lung injury.

This was a retrospective cohort study in a university hospital. The study period was September 2000 through November 2002. In our primary analysis, LPV was defined as use of a tidal volume ≤ 7.5 mL/kg predicted body weight (PBW). We also conducted a sensitivity analysis in which we defined LPV as use of a tidal volume ≤ 6.0 mL/kg PBW.

In our primary analysis, in 42 (56%) of 75 cases, physicians used or intended to use LPV. Of these 42 subjects, 12 received LPV transiently, and 6 never received LPV, despite the fact that the physician ordered or documented LPV use. In 21 of the 33 remaining cases the physicians documented concerns or clinical criteria that may explain why LPV was not used: relative contraindications to LPV (n = 2), change of care goal to comfort care only (n = 1), rapid resolution of hypoxemia (n = 4), and consideration of alternative diagnoses for which LPV was not indicated (n = 14). Of the 12 cases where LPV was used transiently, diagnostic uncertainty (n = 6) was a common finding. The sensitivity analysis yielded explanations in similar proportions.

LPV, once initiated, is often discontinued. Uncertainty in the diagnosis of acute lung injury appears to be an important barrier to initiating and continuing LPV, whereas concerns regarding metabolic acidosis and clinical changes (hypoxemia improved) may prevent the initiation of LPV. Even when physicians believe they are using LPV, they may not be, which suggests that protocol-implementation failure is an important barrier to use of LPV.