COPD
Though the [clinical] diagnosis is admittedly uncertain it is commonly made with serene confidence – CM Fletcher; Pneumoconiosis Research unit at Llandough Hospital in Wales [1].
1) Quiz Link
The diagnosis of Chronic Obstructive Pulmonary Disease (COPD) is established with spirometry (FEV1/FVC < 0.70 post-bronchodilator) [2]. However, many patients present acutely, with COPD suspected but never formally diagnosed. Additionally, only a minority with smoking history or noxious chemical exposure develop COPD. Therefore, some historical and physical exam elements would be helpful to increase suspicion for COPD and to aid (target) referral for spirometry.
In 1952, CM Fletcher reported the results of his clinical experiment in physical signs for “emphysema” (emphysema is a pathological not clinical diagnosis). It led him to conclude:
[The] clinical diagnosis of emphysema… cannot be made with any confidence (at least by a single observer) except perhaps in the most advanced cases, so that there is little hope of the clinician being able to diagnose the early stages [1].
Fletcher only studied 20 patients, but it remains true that only a few historical or physical exam findings have been found to be useful in identifying likely COPD. We will highlight those here.
History
Though noxious chemicals can lead to COPD, smoking is the number one risk factor in the developed world.
Schematic for Chronic Cough
History for COPD
In one study of 309 patients, of which 190 had known or suspected obstructive airway disease (OAD), neither a <20 and 20-40 pack year history of smoking predicted (OAD), only a >40 pack year smoking history predicted OAD [3] Otherwise there were really no other historical elements that were useful, other than self-reported prior diagnosis of OAD.
Physical Exam for COPD
If history is not that helpful, how about exam? Classically, COPD is associated with barrel chest (an increase in the anterior-posterior diameter of the chest relative the the lateral diameter, normal is ~0.7, COPD associated with >0.9). Pursed lips has also been described. But neither is very sensitive, 65% and 58%, respectively) and only pursed lips are moderately specific (78%, while barrel chest is 58% specific) [4].
In OAD the lung hyperinflates. This leads to a number of other changes that are quite specific of OAD.
As the thoracic cavity moves ‘upward’, the laryngeal height, or the distance between the thyroid cartilage and suprasternal notch becomes shorter. When this distance is ≤4 cm it has a pooled specificity of 90% for a LR+ of 3.6 [4].
The hyperinflation has impacts on the heart. Cardiac sounds and the chest becomes hyperresonant (specificity 94-98%, LR+ of 7.3). This increased resonance is particularly notable at the lower left sternal border (~5th intercostal space), which should normally be dull the percussion (specificity 99%, LR+ of 11.8). Similarly the PMI will be displaced inferiorly below the xyphoid process (specificity 99-97%, LR+ of 7.4) [4].
Hoover sign of the lung, or costal paradox, has been described in two different ways. In one, the examiner places his hands on the lower costal margins on each side, and instead of separating during inspiration, the hands (or the costal margins) come together [4]. Alternatively. Hoover sign has been attributed to the finding of paradoxical inspiratory retraction of the intercostal spaces [5]. Of the findings discussed, all specific for COPD, Hoover sign had the highest reproducibility of kappa = 0.74 [4].
The following table summarizes the exam findings for COPD.
Table 1. Physical Exam Operating Characteristics
| Sensitivity | Specificity | LR+ | LR- | kappa | |
|---|---|---|---|---|---|
| Barrel chest | 65 | 58 | 1.5 | 0.6 | 0.62 |
| Pursed lip breathing | 58 | 78 | 2.7 | 0.5 | 0.45 |
| Maximum laryngeal height ≤4 cm | 36 | 90 | 3.6 | 0.7 | 0.59 |
| Hoover sign | 58 | 86 | 4.2 | 0.5 | 0.74 |
| Subxyphoid cardiac impulse | 4-27 | 97-99 | 7.4 | NS | 0.3 |
| Absent cardiac dullness at LLSB | 15 | 99 | 11.8 | NS | 0.49 |
| Hyperresonance, chest | 21-33 | 94-98 | 7.3 | 0.8 | 0.25-0.5 |
There are correlates to point of care ultrasound. Though these have been formally studied to diagnose COPD, the hyperexpanded lung makes parasternal views difficult to obtain (similar to increased resonance at the LLSB). And the subcostal / subxyphoid view of the heart is often improved, analogous to the displaced cardiac impulse.
- CM Fletcher. The clinical diagnosis of pulmonary emphysema; an experimental study. Proc R Soc Med. 1952 Sep;45(9):577-84.
- Global Initiative for Chronic Obstructive Lung Disease. Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease. 2019.
- Straus SE1, McAlister FA, Sackett DL, Deeks JJ. The accuracy of patient history, wheezing, and laryngeal measurements in diagnosing obstructive airway disease. CARE-COAD1 Group. Clinical Assessment of the Reliability of the Examination-Chronic Obstructive Airways Disease. JAMA. 2000 Apr 12;283(14):1853-7.
- Steven McGee, Evidence-Based Physical Diagnosis. 4th Edition, Elsevier, 2018.
- Johnston CR 3rd, Krishnaswamy N, Krishnaswamy G. The Hoover’s Sign of Pulmonary Disease: Molecular Basis and Clinical Relevance. Clin Mol Allergy. 2008 Sep 5;6:8.
