**8. Complications of COPD**

### **8.1 Pneumothorax**

Pneumothorax can precipitate severe dyspnea and acute respiratory failure and may be life threatening since they have only a marginal pulmonary reserve. Presence of giant bullae as part of disease predisposes to this complication. It can be difficult to treat if accompanied by a persistent air leak between the involved lung and the pleural space (bronchopleural fistula).

Current Overview of COPD with Special Reference to Emphysema 135

asthma and could exclude COPD. Because of variability in the FVC (or FEV6) measure, the FEV1/FVC ratio can establish a diagnosis of obstruction but is not useful to monitor disease progression(GOLD,2006). FEV1/FVC ratio is the basis for GOLD staging of COPD(see Table 2).

Stage FEV1\*/FVC\*\*(in %) FEV1\*(in % of predicted)

IV: Very Severe COPD <70 % <30% or <50% with chronic

Other spirometric findings include decreased inspiratory capacity and vital capacity, accompanied by increased total lung capacity, functional residual capacity, and residual volume are indicative of hyperinflation. The single breath carbon monoxide diffusing capacity (DLCO) decreases in proportion to the severity of emphysema because of the

Arterial blood gases reveal mild or moderate hypoxemia without hypercapnia in the early stages of COPD. In the later stages of the disease, hypoxemia tends to become more severe and may be accompanied by hypercapnia with increased serum bicarbonate levels(Bates,1989). The changes in ABG represent ventilation perfusion mismatch, which

Of the approximately 75 different alleles for alpha1-antitrypsin (AAT) deficiency variants, 10-15 are associated with serum levels below the protective threshold of 11 µmol/dL. The most common severe variant is the Z allele, which accounts for 95% of the clinically recognized cases of severe AAT deficiency. The diagnosis of severe AAT deficiency is confirmed when the serum level falls below the protective threshold value (ie, 3-7 µmol/dL). Specific phenotyping is reserved for patients in whom serum levels are 7-11

In patients with stable chronic bronchitis, the sputum is mucoid and the predominant cells are macrophages(Miravitlles,2002;Sethi et al.,2002 as cited in Shapiro SD,2010). With an exacerbation, the sputum becomes purulent, with excessive neutrophils and a mixture of organisms visualized through Gram staining. *Streptococcus pneumoniae* and *Haemophilus* 

\*FEV1: forced expiratory volume in one second; \*\*FVC: forced vital capacity; \*\*\*Chronic respiratory failure: arterial partial pressure of oxygen (PaO2) less than 60 mm Hg (8.0 kPa) with or without arterial partial pressure of CO2 (PaCO2) greater than 50 mm Hg (6.7 kPa) while breathing air at sea level.

respiratory failure\*\*\*

I: Mild COPD <70 % ≥80 % II: Moderate COPD <70 % 50 % to <80% III: Severe COPD <70 % 30% to <50%

destruction of the alveoli and the loss of alveolar capillary bed.(Bates,1989)

may be worsened during exercise, sleep and episodes of exacerbation.

µmol/dL or when genetic counseling or family analysis is needed.

*influenzae* are pathogens frequently cultured during exacerbations.

Table 2. Staging of severity of COPD (GOLD,2006)

**9.2 Arterial blood gas** 

**9.3 Alpha1-antitrypsin level** 

**9.4 Sputum evaluation** 
