Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise in arterial carbon dioxide levels is called hypercapnia. Respiratory failure is classified as either Type 1 or Type 2, based on whether there is a high carbon dioxide level, and can be acute or chronic. In clinical trials, the definition of respiratory failure usually includes increased respiratory rate, abnormal blood gases (hypoxemia, hypercapnia, or both), and evidence of increased work of breathing. Respiratory failure causes an altered state of consciousness due to ischemia in the brain.

The typical partial pressure reference values are oxygen Pa Oxygen| more than 80 mmHg (11 kPa) and carbon dioxide Pa Carbon dioxide| less than 45 mmHg (6.0 kPa). The etiologies of each type of respiratory failure (see below) may differ, as well. Different types of conditions may cause respiratory failure:

  • Conditions that reduce the flow of air into and out of the lungs, including physical obstruction by foreign bodies or masses and reduced breathing due to drugs or changes to the chest. motor neuron disease)
  • Deformed (kyphoscoliosis), rigid (ankylosing spondylitis), or flail chest.

The pathophysiology of type 3 respiratory failure often includes lung atelectasis, which is a term used to describe a collapsing of the functional units of the lung that allow for gas exchange. Because atelectasis occurs so commonly in the perioperative period, this form is also called perioperative respiratory failure. After general anesthesia, decreases in functional residual capacity leads to collapse of dependent lung units.

Physical exam

Physical exam findings often found in patients with respiratory failure include findings indicative of impaired oxygenation (low blood oxygen level). These include, but are not limited to, the following:

  • Accessory muscle use in breathing or other signs of respiratory distress
  • Altered mental status (eg. confusion, lethargy) The treatment of acute respiratory failure may involve medication such as bronchodilators (for airways disease), antibiotics (for infections), glucocorticoids (for numerous causes), diuretics (for pulmonary oedema), amongst others. Respiratory failure resulting from an overdose of opioids may be treated with the antidote naloxone. In contrast, most benzodiazepine overdose does not benefit from its antidote, flumazenil. Respiratory therapy/respiratory physiotherapy may be beneficial in some cases of respiratory failure.

Type 1 respiratory failure may require oxygen therapy to achieve adequate oxygen saturation. Lack of oxygen response may indicate other modalities such as heated humidified high-flow therapy, continuous positive airway pressure or (if severe) endotracheal intubation and mechanical ventilation. .

Type 2 respiratory failure often requires non-invasive ventilation (NIV) unless medical therapy can improve the situation. Mechanical ventilation is sometimes indicated immediately or otherwise if NIV fails.

There is tentative evidence that in those with respiratory failure identified before arrival in hospital, continuous positive airway pressure can be helpful when started before conveying to hospital.

Prognosis

Prognosis is highly variable and dependent on etiology and availability of appropriate treatment and management. One of three hospitalized cases of acute respiratory failure is fatal.