This document summarizes the bedside test that are used in the chest medicine

1. Bedside tests in Chest/Pulmonary Medicine :
1.Sputum examination
Collect a good sample; if necessary ask a physiotherapist to
help. Note the appearance: clear and colourless (chronic
bronchitis), yellowgreen (pulmonary infection), red
(haemoptysis), black (smoke, coal dust), or frothy white-pink
(pulmonary oedema). Send the sample to the laboratory for
microscopy (Gram stain and auramine/ZN stain, if indicated),
culture, and cytology.
2.Peak expiratory flow (PEF)
Is measured by a maximal forced expiration through a peak
flow meter. It correlates well with the forced expiratory
volume in 1 second (FEV1) and is used as an estimate of
airway calibre, but is more effort-dependent.
3.Pulse oximetry :
Allows non-invasive assessment of peripheral O2 saturation
(SpO2). It provides a useful tool for monitoring those who are
acutely ill or at risk of deterioration. An oxygen saturation of
≤80% is clearly abnormal and action is usually required,
unless this is usual for the patient, eg in COPD. If a previously
healthy person has pneumonia, a saturation of <92% is a
serious sign. Here, check arterial blood gases (ABG) as PaCO2
may be rising despite a normal PaO2. Causes of erroneous
readings: poor perfusion, motion, excess light, skin

2. pigmentation, nail varnish, dyshaemoglobinaemias, and
carbon monoxide poisoning. As with any bedside test, be
sceptical, and check ABG, whenever indicated.
4. Arterial blood gas (ABG) :
Heparinized blood is usually taken from the radial or femoral
artery, and pH, PaO2, and PaCO2 are measured using an
automated analyser. Remember to note FiO2 (fraction or
percentage of inspired O2).
• Normal pH is 7.35–7.45. A pH <7.35 indicates acidosis and a
pH >7.45 indicates alkalosis. For interpretation of
abnormalities, see p684.
• Normal PaO2 is 10.5–13.5kPa. Hypoxia is caused by one or
more of the following
Reasons: ventilation/perfusion (V/Q) mismatch,
hypoventilation, abnormal diffusion, right to left cardiac
shunts. Of these, V/Q mismatch is the commonest cause.
Severe hypoxia is defined as a PaO2 <8kPa .
• Normal PaCO2 is 4.5–6.0kPa. PaCO2 is directly related to
alveolar ventilation. A PaCO2 <4.5kPa indicates
hyperventilation and a PaCO2 >6.0kPa indicates
hypoventilation.
Type 1 respiratory failure is defined as PaO2 <8kPa and
PaCO2 <6.0kPa.

3. Type 2 respiratory failure is defined as PaO2 <8kPa and
PaCO2 >6.0kPa.
5.Spirometry :
Measures functional lung volumes. Forced expiratory volume
in 1s (FEV1) and forced vital capacity (FVC) are measured
from a full forced expiration into a spirometer (Vitalograph);
exhalation continues until no more breath can be exhaled.
FEV1 is less effort-dependent than PEF. The FEV1/FVC ratio
gives a good estimate of the severity of airflow obstruction;
normal ratio is 75–80%.
Obstructive defect (eg asthma, COPD) FEV1 is reduced more
than the FVC, and the FEV1/FVC ratio is <75%.
Restrictive defect (eg lung fibrosis) FVC is decreased and the
FEV1/FVC ratio is increased or normal .
Other causes: sarcoidosis; pneumoconiosis, interstitial
pneumonias; connective tissue diseases; pleural effusion;
obesity; kyphoscoliosis; neuromuscular problems.