Hypoxaemia
Original Editor - Adam Vallely Farrell
Top Contributors - Adam Vallely Farrell, Lucinda hampton, Abbey Wright, Kim Jackson, Rishika Babburu and Chelsea Mclene
Respiratory Failure[edit | edit source]
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)[edit | edit source]
Hypoxaemia is defined as the inability to maintain the PaO2 above 8kPa
Classification and Causes of Hypoxaemia[edit | edit source]
Classification | Cause | |
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Hypoxic hypoxaemia |
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Ischaemic hypoxaemia |
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Anaemic hypoxaemia |
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Toxic hypoxaemia |
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E.g. carbon monoxide poisoning, cyanide poisoning |
Clinical Signs[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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.
Controlled Oxygen Therapy[edit | edit source]
- Oxygen is a drug which should be prescribed for the required percentage and/or flow rate
- Usually 24-60% can be given by an oxygen mask
- 2-4L/min via nasal cannulae; however, a mask may be preferable if hypoxic and/or mouth breather
- Over 60% oxygen with persistently low sats (<90%) use a non-rebreather mask to administer constant flow of high concentration oxygen
- CPAP is useful with profound hypoxaemia once pneumothorax excluded
Humidification[edit | edit source]
- Consider cold or heated humidification
- Heated is better for tenacious secretions or severe bronchospasm
Treat the cause, e.g. bronchospasm, sputum retention, volume loss[edit | edit source]
- If primary respiratory problem, treat this
- If primary problem is cardiac or renal, discuss this with the medical team
Increased work of breathing[edit | edit source]
- Use airway clearance techniques if needed
- Positioning is essential to reduce breathlessness and improve ventilation perfusion matching
- IPPB may be useful (with a high flow rate) to rest the muscles and improve efficacy of other treatments
Common Issues in Hypoxaemia[edit | edit source]
Bronchopneumonia[edit | edit source]
- Ensure medication is optimised (oxygen, analgesia, bronchodilators, antibiotics, etc.)
- Positioning to decrease work of breathing
- Airway clearance techniques
- Humidification
Acute lobar pneumonia[edit | edit source]
- During the unproductive phase advice on positioning may reduce WOB
- CPAP is useful for hypoxaemia
- Sputum clearance s only indicated if the patient becomes productive
Pulmonary embolus[edit | edit source]
- physiotherapy is not indicated. CPAP may help with severe hypoxaemia
Pulmonary fibrosis[edit | edit source]
- Present with profound hypoxaemia. Humidified CPAP is effective
- Ensure sufficient oxygen is available when CPAP removed
Pulmonary oedema[edit | edit source]
- CPAP is effective in the treatment of pulmonary oedema
- If hypotensive, check that BP does not drop with increased intrathoracic pressure.
- NIV (pressure support with EPAP) may be useful in the patient tiring on CPAP
CO2 retention[edit | edit source]
- Acute CO2 retention is not a reason to reduce FiO2 unless patients have evidence of acute-on-chronic CO2 retention secondary to chronic respiratory disease
- This can be diagnosed by interpretation of recent blood gas results, assessing pH, in relation to PaCO2, standard bicarbonate and base excess. Only this group of patients require judicious oxygen administration )24-28%), which should be prescribed accordingly
Fatigue[edit | edit source]
- Hypoxaemic patients may start to fatigue. This is seen by a rising PaCO2 - type II failure. An important clinical sign requiring immediate attention
Chronic chest patients[edit | edit source]
- Patients who have longstanding chest diseases may have a regular chest clearing routine they adhere to e.g. Bronchiectatic, CF patient
- It is important to discuss this and mould your treatment plan so that it fits within their existing regimen and their current physiotherapy problems
Renal failure[edit | edit source]
- Patient in renal failure may present with an increased work of breathing
- ABGs will show metabolic acidosis, generally with some form of respiratory ompensation e.g. Decreased CO2
- Pulmonary oedema and pleural effusion may also be present
Distended abdomen, e.g. pancreatitis, ascites[edit | edit source]
- Positioning in alternate side-lying or well supported high side-lying is useful
- Standing where possible
Oesophageal varices[edit | edit source]
- Dilated blood vessels in the oesophagus can rupture with increased pressure
- Care should be taken when coughing, suctioning is contraindicated
- Prevent chest infection by positioning, teaching huff, mobilize if tolerated