Value based interpretation of pulmonary function tests

Two contrasting errors in spirometric interpretation are the inappropriate conclusion of "normality" (type I) and of "abnormality" (type II). A survey of 67 health professionals showed major interpersonal and intersituational differences in opinion about the optimal relative proportions of type I and type II errors. This suggests the need for caution in the commonly employed practice of interpretation based on a 5 percent false positive rate.     

Pulmonary function tests in preoperative pulmonary evaluation

Pulmonary function testing (PFT) has been used to evaluate the risk for postoperative complications since the 1950s. PFT including spirometry, lung volumes, diffusing capacity, oximetry, and arterial blood gases has been used to assess the postoperative risk of lung resection. In selected cases, additional evaluation may include radionuclide lung scanning, exercise testing, invasive pulmonary hemodynamic measurements, and risk stratification analysis. A new index, predicted postoperative product (PPP), was found to have strong predictive ability for mortality. We defined a new useful index, measured product (MP), to predict postoperative complications; MP had similar advantages of PPP. Since diffusing capacity at rest has been shown to be a good predictor of postoperative complications following lung resection, and since exercise testing has been also useful in preoperative evaluation prior to lung resection, we reasoned that evaluation of the effect of exercise on diffusing capacity would be helpful to evaluate the ability of the pulmonary capillary bed to expand and increase its capacity to transfer gas during exercise.     

Amiodarone pulmonary toxicity: Prospective evaluation of serial pulmonary function tests

Pulmonary toxicity developed in 15 (17%) of 89 patients treated with amiodarone during a follow-up period of 2 weeks to 54 (mean 20 ± 15) months. Prospective evaluation of serial pulmonary function tests in 67 patients demonstrated both a significant decrease from baseline in three of six variables in patients with toxicity at the time of diagnosis and a significant difference compared with the same variables in patients without toxicity. The most significant of these was the diffusing capacity for carbon monoxide (D_LCO). An individual decrease in D_LCO ≥ 15% gave an optimal sensitivity of 100% and a specificity of 89% for the diagnosis of pulmonary toxicity. However, a decrease in D_LCO ≥ 15% did not alone warrant a change in therapy in asymptomatic patients. Although higher maintenance doses of amiodarone appeared to be related to the development of this complication, an abnormal baseline D_LCO (< 60% of predicted) with or without an initial abnormal chest roentgenogram did not predispose to pulmonary toxicity.     

Pulmonary function tests in preoperative pulmonary evaluation.

Pulmonary function testing (PFT) is used extensively by pulmonary specialists to address two common clinical questions: (1) What is the risk of a postoperative pulmonary complication in an individual with lung disease? and (2) Will the patient be able to tolerate lung resection surgery? Today, there are numerous tests available to measure pulmonary function; making judicious use of these tests essential. In this article, the authors describe significant postoperative pulmonary complications, and discuss the surgical and patient factors contributing to the risk of these complications. They provide an evidence-based approach using pulmonary function data to determine an individual patient's risk for pulmonary complications associated with three types of surgical procedures-upper abdominal, cardiac, and lung resection-and discuss recommendations for risk education.     

Variability of pulmonary function tests in cystic fibrosis

The aim of this study was to define the within-subject variability for tests of respiratory function in patients with cystic fibrosis (CF) within the day, from day to day and from week to week. Twenty-eight patients with CF (aged 9-19 years) and 23 healthy height matched controls (aged 9-18 years) had measurements made of spirometry, lung volumes, maximal flows at three lung volumes and maximal inspiratory and expiratory pressures at the mouth. Testings were done on nine occasions, three times within a day, on consecutive days at one week intervals. Each individual's variability was summarized both as the within-subject coefficient of variation (WCV) and within-subject standard deviation (WSD). Means of WSD and median WCV are reported for both the patients with CF and normal subjects. The within-subject variability of VC, FEV1, TLC, RV, and RV/TLC was more appropriately assessed by the use of WSD rather than WCV. The WSDs in the CF group were significantly more variable (P less than 0.005) than in the normals for VC and FEV1. WCV best summarized within-subject variation for FEF25-75, FRC, V25, V50max and V75max for which the CF subjects were significantly more variable (P less than 0.005). Individuals' variability was very consistent, therefore assessment of significant change could be made more accurately by predetermining the variability of that individual, rather than using group data. We stress the importance to consider increased variability from day to day and week to week in the interpretation of change in lung function in patients with CF, and provide reference values for accurate interpretation of serial pulmonary function test results.     

Assessment of pulmonary function tests in cardiac patients

This study was aimed to assess the pulmonary function tests (PFTs) in cardiac patients; with ischemic or rheumatic heart diseases as well as in patients who underwent coronary artery bypass graft (CABG) or valvular procedures. For the forty eligible participants, the pulmonary function was measured using the spirometry test before and after the cardiac surgery. Data collection sheet was used for the patient’s demographic and intra-operative information. Cardiac diseases and surgeries had restrictive negative impact on PFTs. Before surgery, vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), ratio between FEV1 and FVC, and maximum voluntary ventilation (MVV) recorded lower values for rheumatic patients than ischemic patients (P values were 0.01, 0.005, 0.0001, 0.031, and 0.035, respectively). Moreover, patients who underwent valvular surgery had lower PFTs than patients who underwent CABG with significant differences for VC, FVC, FEV1, and MVV tests (P values were 0.043, 0.011, 0.040, and 0.020, respectively). No definite causative factor appeared to be responsible for those results although mechanical deficiency and incisional chest pain caused by cardiac surgery are doubtful. More comprehensive investigation is required to resolve the case.     

Clinical significance of pulmonary function tests. Alterations in pulmonary function following respiratory viral infection.

Respiratory viral illness is a major cause of morbidity in both adults and children. This report focuses on both the acute and chronic effects on respiratory function of these ubiquitous infections. Infant airways are particularly vulnerable due to the relatively low conductance in immature peripheral airways. Bronchiolitis, caused predominantly by respiratory syncytial virus, is the most important of these viral illnesses and is emerging as a major risk factor for the subsequent development of obstructive airway diseases in adults, possibly by interference with normal alveolar proliferation. The basic pathogenic mechanism involved in adult respiratory viral infection is bronchial hyperreactivity, presumably secondary to epithelial damage and resultant sensitization of rapidly adapting airway receptors. In addition, there may be virus-related alterations in the autonomic and humoral regulation of airway tone. Viral infections may alter the effects of common air pollutants on respiratory function.     

Adult-type pulmonary function tests in infants without respiratory disease

A new method that permits the measurement of adult-type maximal expiratory flow-volume curves and fractional lung volumes in sedated infants was recently described. The purpose of this study was to define the normal range for these new measures of pulmonary function in infants and young children. Measurements of forced expiratory flows and fractional lung volume were made on 35 occasions in 22 children (ages 3-120 weeks) without respiratory disease. Maximal expiratory flow-volume curves were measured by the raised lung volume, thoracoabdominal compression technique. Functional residual capacity (FRC) was measured plethysmographically. Measurements of total lung capacity (TLC), residual volume (RV), FRC, forced vital capacity (FVC), and forced expiratory flows at 25, 50, 75, 85, and between 25% and 75% of expired FVC (FEF(25), FEF(50), FEF(75), FEF(85), and FEF(25-75), respectively) all increased in relation to infant length (P<0.001). RV/TLC, FRC/TLC, and FEF(25-75)/FVC declined in relation to increasing length (P<0.001). The forced expiratory flow and fractional lung volume measurements using this method were similar to previously reported estimates using other methods. These estimates represent a reasonable reference standard for infants and young children with respiratory problems.