The pressure inside the chest (intrathoracic cavity) is -8 cm/H2O, which is lower than atmospheric pressure (negative pressure).
In natural breathing, the membrane (diaphragm) that separates the lungs and the stomach (diaphragm) pulls the deflated balloon (lungs) toward the legs and expands it. (negative pressure breathing).
However, when breathing with an artificial respirator (respirator), air is pushed (pressurized) into the deflated balloon (lungs) with a device to inhale, and a certain amount of air enters the balloon (lungs). Stop pushing at the top and breathe out through your mouth (positive pressure breathing).
When you breathe on a ventilator, the machine pushes air into the lungs (positive pressure ventilation), so high pressure air enters the lungs and alveoli, causing the lungs to overinflate or rupture the alveoli (barotrauma). This causes air to leak around the lungs and pressurize the lungs (pneumothorax), making it difficult to breathe. Rarely, the blood pumped out becomes lower, resulting in lower blood pressure (hypertension) or less urine (low urine volume).As a countermeasure for these, reduce the amount of air to push (1 ventilation volume).
When the lungs are ventilated with a high concentration of oxygen (positive pressure breathing), oxygen in the blood increases and carbon dioxide decreases, causing the blood to become alkaline (alkalosis). There may be less blood being pumped out (decreased cardiac output) and seizures may occur.
Since a tube is inserted into the trachea (tracheal intubation) to attach a respirator, there is a risk of infection from there and pneumonia (ventilator-associated pneumonia: VAP).In order not to cause complications due to these artificial respiration management, it is necessary to nurse so that the time to put on the respirator is not prolonged.
In addition, even if the lungs with severe respiratory failure are inflated with air using an artificial respirator, there is a limit that the lungs themselves cannot take in enough oxygen and exhaust carbon dioxide (gas exchange).
A ventilator is mainly used to take in oxygen (oxygenation), maintain and improve ventilation, and reduce the burden on breathing (work of breathing).Take preventive care to avoid complications.
Faculty of Health Sciences Department of Nursing Emiko Takamizawa
