The validity and reliability of the clinical assessment of increased work of breathing in acutely ill patients.

BACKGROUND: Mechanical ventilation is frequently indicated to reduce the work of breathing. Because it cannot be measured easily at the bedside, physicians rely on surrogate measurements such as patient appearance of distress and increased breathing effort. OBJECTIVE: We determined the validity and reliability of subjectively rating the appearance of respiratory distress and the reliability of 11 signs of increased breathing effort. SUBJECTS: The study included consecutive, acutely ill patients requiring various levels of respiratory support. METHODS: Blinded to each other's observations, a fellow and a critical care consultant rated the severity of distress (absent, slight, moderate, severe) after observing subjects for 10 seconds and then determined the presence of the signs of increased breathing effort. RESULTS: A total of 149 paired examinations occurred 6±6 minutes apart. The rating of respiratory distress correlated with oxygenation, respiratory rate, and 9 signs of increased work of breathing. It had the highest intraclass correlation coefficient (0.69; 95% confidence interval, 0.59-0.78). Rating distress as moderate to severe had a sensitivity of 70%, specificity of 92%, and positive likelihood ratio of 8 for the presence of 3 or more of hypoxia, tachypnea, and any sign of increased breathing effort. Agreement was moderate (κ = 0.53-0.47) for rating of distress, nasal flaring, scalene contraction, gasping, and abdominal muscle contraction, and fair (κ = 0.36-0.23) for sternomastoid contraction, tracheal tug, and thoracoabdominal paradox. CONCLUSION: Assessing the increased work of breathing by rating the severity of respiratory distress based on subject appearance is a valid and moderately reliable sign that predicts the presence of serious respiratory dysfunction. The reliability of the individual signs of increased breathing effort is moderate at best.

Is the content of textbooks on the evaluation of a patient in respiratory distress adequate?

BACKGROUND: The ability to rapidly and precisely evaluate patients in respiratory distress is essential. Due to limited opportunities for formal instruction during training, textbooks are the main educational source to teach junior physicians how to interpret the signs of respiratory distress. The quality of the textbook content relevant to respiratory distress is unknown. OBJECTIVE: To examine the content on the evaluation of a patient in respiratory distress in a representative sample of textbooks and Internet resources. METHODS: Two physicians individually reviewed the most recent edition of 21 standard textbooks from a variety of specialties. Smartphone applications, UptoDate, and MD Consult were examined. Each physician reviewed the source for 14 different signs. For each sign, the reviewers determined 3 parameters: a mention of the sign, its pathophysiology, and its detection. The reviews were compared for discrepancies, and a third reviewer resolved them. RESULTS: The normal respiratory rate was mentioned in 10 (48%) of textbooks, and ranged between 10 and 22 breaths/min. Each sign was mentioned by a mean of 45 ± 26% of the textbooks. The pathophysiology of the signs was described by a mean of 33 ± 30% of the textbooks. The most and least commonly mentioned inspection signs were cyanosis and retraction of suprasternal notch, respectively. They were mentioned in 20 (95%) and 4 (19%) textbooks, respectively. The most and least commonly mentioned palpation signs were thoracoabdominal asynchrony or paradox and tracheal tug, respectively. They were mentioned in 17 (81%) and 4 (19%) textbooks, and their pathophysiology was described in 15 (71%) and 4 (19%) textbooks, respectively. The reviewers also found inconsistency in the descriptions of the meaning of scalene muscle contraction and thoracoabdominal asynchrony and paradox. CONCLUSIONS: The content of the reviewed textbooks on the evaluation of respiratory distress is inconsistent and deficient.

Lung disease caused by exposure to coal mine and silica dust.

Susceptible workers exposed to coal mine and silica dust may develop a variety of pulmonary diseases. The prime example is classical pneumoconiosis, a nodular interstitial lung disease that, in severe cases, may lead to progressive massive fibrosis (PMF) . Exposure to silica and coal mine dusts may also result in pulmonary scarring in a pattern that mimics idiopathic pulmonary fibrosis, and in chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis, that appears indistinguishable from obstructive lung disease caused by exposure to tobacco smoke. Coal mine and silica dust may therefore result in restrictive, obstructive, or mixed patterns of impairment on pulmonary function testing. Most physicians are aware of the nodular fibrosing pulmonary tissue reactions in response to retained dust, but they may not realize that these other reactions of the pulmonary parenchyma and airways to dust exist and can result in significant respiratory dysfunction in sensitive individuals. This article discusses current data on exposure to coal mine and silica dust in the United States, the epidemiology of the diseases caused by these exposures, and new concepts of causation and pathogenesis. We also review the patterns of pulmonary disease and impairment that may result.