A medical ventilator is a biomedical device which provide a mechanical ventilation for the lungs allowing the air to get in and get out cyclically being a ventilatory support to the respiratory system. The respiratory system can fail due to many causes being pulmonary or extrapulmonary and It works as a mechanical support to the physiological “ventilatory pump” which is created by the diaphragm and accessory muscles of respiration. The haematosis is the gas exchange between carbon dioxide and oxygen a made in the lungs which is not replaced by the ventilator. The medical ventilator allowed to increase the number of Intensive Care Units allowing the treatment of patients with severe conditions.
The use of biomedical ventilators in asthmatic crisis can decrease the respiratory work created by increase airway resistance and levels of hyperinflation. Also, can avoid the barotrauma and maintaining the patient stable while drug treatment with bronchodilators and corticosteroids reduces airway resistance, reversing the asthma attack and allowing the patient to resume spontaneous breathing.
Currently, the biomedical ventilator is classified into two major groups: Invasive mechanical ventilation and Non-invasive ventilation. In both situations, artificial ventilation is achieved by applying positive airway pressure. The difference between them is the way that pressure is released, while in invasive ventilation a prosthesis is introduced into the airway, a nasotracheal tube (less common) can be introduced or a tracheostomy cannula can be made to perform the ventilation. On the other hand, the non-invasive ventilation a mask is provided as the interface between the patient and the artificial ventilator.
Adjusting the mechanical ventilation promptly in asthmatic patients is a challenge for the physicians because they are patients with hemodynamic and respiratory changes. The asthma creates a hyperinflation of the lungs which causes hemodynamic and ventilatory muscles effects such as diaphragm damages which makes positive pressure ventilation hardier. The mechanical ventilation strategy has the goal to correct the hyperinflation repairing the bronchospasm.
The asthmatic patient is not a kind of patient which should stay with the respirator for a long period then, it is necessary to optimize treatment to remove them from the respirator as soon as possible mainly when they are using the invasive technique. Another reason to avoid leaving these patients long periods in respirator is that the asthmatic patients are more susceptible to air trapping, which is the trapping of air during mechanical ventilation. To prevent that it is necessary to ventilate at a very low respiratory rate.
A high peak pressure inside the ventilator is expected while used in asthmatics, mainly due to increased ventilatory resistance. The increased airway resistance is not homogeneous and non-affected areas may receive large volumes of air generating high trans-alveolar pressures generating barotrauma. Also, the hyperinflation can generate a higher respiratory work including an intense muscle contraction. Finally, hyperinflation changes the curvature of the diaphragm which may become less efficiency.
All these deleterious effects can justify the importance of the correctly adjustment of the biomedical ventilator parameters in order to reduce these effects. The biomedical ventilator is a very import device which can support asthmatic patients during their crises.