Generic Investigations

All patients in respiratory distress require:

  • Pulse oximetry
  • Chest radiography
  • ECG
  • ABG
  • Consideration of ancillary investigations

Indications listed below.

Generic investigations are outlined as follows:

Test Comment
Pulse oximetry Essential in all patients presenting with dyspnoea

Determine degree of hypoxia

Determine need for, and response to, oxygen supplementation

Arterial blood gases Essential in all patients with respiratory distress

Essential in all patients with suspected metabolic disturbance

Accurate determination of acid/base status

Accurate determination of O2/CO2 status

Determination of metabolic or respiratory/acidosis or alkalosis

Determination of Alveolar-arterial (A-a) gradient

Determines the need for supplemental oxygen or ventilatory support

Determines response to supplemental oxygen or ventilatory support

CXR Essential in all patients with respiratory distress of possible cardiorespiratory aetiology

To support clinical diagnosis (e.g. pneumonia)

To quantify severity of pathology (e.g. pulmonary oedema, effusion)

To exclude certain pathologies (e.g. pneumothorax)

Generically if diagnosis uncertain (e.g. COPD vs LVF)

ECG Essential in all patients with respiratory distress associated with ischaemic pain acute coronary syndrome (ACS) or other possible cardiac pathology

To determine presence of right ventricular strain in patients with possible pulmonary embolism or pulmonary hypertension

Each test is discussed on the next four pages.