Indications of Mechanical Ventilation
Indications of Mechanical Ventilation
Dr. Abdelsadek Al-Aarag ,MD,MERS,FCCP.
Professor of Pulmonology,
Former Head of Chest Department,
Faculty of Medicine-Benha Univeresity.
Indications for intubation
Indications for intubation :
1-Need to secure airway.
2-Depressed sensorium.
3-Depressed airway reflexes.
4-Upper airway stability after trauma.
5-Decreased airway patency.
6-Need for sedation in the setting of poor airway control.
7- Imaging and transportation of an unstable patient
Indications for ventilation
1-Hypoxia with acute hypoxemic respiratory failure.
2-Hypoventilation.
3-Unacceeptably high work of breathing.
4-Hemodynamic compromise.
5-Cardiorespiratory arrest.
6-Refractory shock.
7-Raised intracranial pressure;
8-Flail chest.
Mechanical ventilation is indicated when spontaneous ventilation is inadequate for the sustenance of life. Mechanical ventilation is not a cure for the disease for which it is instituted , it is at best a form of support , offering time and rest to the patient until the underlying disease processes are resolved. Results with mechanical ventilation are better when mechanical ventilator support is initiated early and electively.
The indications for mechanical ventilation may be viewed as falling under several broad categories.
1- Hypoxia:
Mechanical ventilation is often electively instituted when it is not possible to maintain an adequate oxygen saturation of hemoglobin (Sa2). Increasing the fraction of inspired oxygen (FIO2) indiscriminately in an attempt to improve oxygenation may subject the patient to the danger of oxygen toxicity. Mechanical ventilation enables better control of hypoxemia with relatively low inspired O2 concentration thereby diminishing the risk of oxygen toxicity.
2- Hypoventilation:
A major indication for mechanical ventilation is when the alveolar ventilation falls . Conditions that depress the respiratory center produce a decline in alveolar ventilation with a rise in arterial CO2 tension. A rising PaCO2 can also result from the hypoventilation that results from respiratory muscle fatigue so become unable to sustain ventilation , as in a patient who is doing excessive effort in moving air into obstructed airways or stiffened lungs . Under such conditions , mechanical ventilation may be used to support gas exchange until the patient”s respiratory drive has been retained , or tired respiratory muscles improved, and the inciting pathology significantly resolved.
Causes of Hypoventilation:
Hypoventilation results from decreased bulk flow in and out of the lungs. Inspiration results in the bulk flow of air into the lungs up to the level of the smallest bronchioles. Further progress of the gas molecules is by the mechanism of diffusion peripherally.
Disorders in which bulk flow to the lungs is compromised include:
- Sedative agents
- Cerebrovascular accidents
- Central sleep apnea
- Metabolic alkalosis
- Myxedema
- Hypoxia
- Hyperoxic hypoventilation
2- Spinal cord or peripheral nerve disorders:
- Spinal trauma - Amyotrophic lateral sclerosis
- Poliomyelitis - Multiple sclerosis
- Guillian-Baree syndrome
- Botulism
3- Neuro-muscular disorders:
- Myasthenia gravis - Muscular dystrophies - Dyselectrolytemias
-Respiratory muscle fatigue -Steroid myopathy
- Aminoglycosides
- Paralysing agents
4- Disorders affecting the thoracic cage:
- Kyphoscoliosis
- Flail chest
- Ankylosing spondylitis
5- Proximal airway (extrapulmonary airway obstruction):
-Tracheal obstruction by stenosis, tumour------etc.
- Obstructive sleep apnea
3- Increased work of breathing:
Another major category where assisted ventilation is used is in those situations in which excessive work of breathing results in hemodynamic compromise. Here , even gas exchange may not be actually impaired, the increased work of breathing (due to high airway resistance or poor lung compliance) may impose an increased burden on a compromised myocardium.
When oxygen delivery to the tissues is compromised secondary to impaired myocardial function, mechanical ventilation by resting the respiratory muscles can reduce the work of breathing. This reduces the oxygen consumption of the respiratory muscles and results in better perfusion of the myocardium itself
(+2) 05 / 54334283 - 54334282 - 54334285
info@utopiapharma.com
4 Hassan Maamoun St.,Al Maamoun TowerNasr City, Cairo, Egypt.