Hypoxaemia

Original Editor - Adam Vallely Farrell

Top Contributors - Adam Vallely Farrell, Lucinda hampton, Abbey Wright, Kim Jackson, Rishika Babburu and Chelsea Mclene  

Respiratory Failure

Respiratory failure is demonstrated in arterial blood gas (ABG) tensions. Type I respiratory failure is defined as PaO2 <8.0kPa with a normal or lowered PaCO2. Type II respiratory failure (ventilatory failure) is defined as PaO2 <8.0kPa and a PaCO2 >6.0kPa. Acute respiratory failure is related to respiratory distress, with increased work of breathing and deranged gas exchange. It may occur with or without the presence of excessive pulmonary secretions and/or sputum retention., and is not necessarily related to a primary respiratory problem, e.g. neurological problems may be related to respiratory depression, hypoventilation, reduced level of consciousness and inability to protect the airway. Cough depression and risk of aspiration are a serious concern. Unrecognised respiratory failure leads to;

• respiratory muscle fatigue
• hypoventilation
• sputum retention
• Decreased O2 (hypoxaemia)

Acute assessment to establish the underlying cause is imperative as, if left untreated, it may progress to any or all of the following;

• cardiac arrhytmia
• cerebral hypoxaemia
• respiratory acidosis
• coma
• cardiorespiratory arrest

Thus, timely recognition and treatment of respiratory failure is of the utmost importance and a serious part of a patients care.

Hypoxaemia (Type 1 Respiratory Failure)

Hypoxaemia is defined as the inability to maintain the PaO2 above 8kPa

Classification and Causes of Hypoxaemia

Hypoxic hypoxaemia

Ischaemic hypoxaemia

Anaemic hypoxaemia

Toxic hypoxaemia

Clinical Signs

A patient with hypoxaemia will display some/all of the following symptoms;

• central cyanosis (blue lips, tongue)
• peripheral shut-down (cool to touch, 'cold and clammy')
• tachypnoea - increased respiratory rate (>20 beats per minute)
• low oxygen saturation (<90%)
• confusion or agitation if profound hypoxaemia, may be non compliant with treatment

Aim of Physiotherapy

To identify and treat, if appropriate, the cause of the hypoxaemia, thus aiming to increase PaO2 >8kPa while administering appropriate oxygen therapy

Treatment of Hypoxaemia

The primary treatment of hypoxaemia is controlled oxygen therapy, plus identification and treatment of the underlying cause. Patients who are unable to maintain SaO2 >90% on face mask oxygen may require additional respiratory support, either continuous positive airway pressure (CPAP) or intubation and mechanical ventilation. Patients with unilateral lung disease can be positioned in side-lying, with the unaffected lung down, to try to improve V/Q matching.