Factors affecting tidal volume

Maintenance of eucapnia is sometimes only possible with strategies that increase the risk of ventilator-induced lung injury, including the use of a tidal volume that causes alveolar overdistension. In these situations (e.g. acute lung injury), the risk can be reduced by decreasing tidal volume and therefore peak alveolar pressure. If the respiratory rate, physiological dead-space, and CO 2 production remain constant, Paco2 will rise. This may be appropriate if there is no significant...

CPAP and intracranial pressure regulation

Some concern may arise when CPAP is delivered to patients with increased intracranial pressure. Positive intrathoracic pressure may indeed decrease venous return and act as a resistive component to venous return from the head, thus increasing intracranial venous pressure and eventually parenchymal intracranial pressure. Decreased systemic venous return may also decrease cardiac output and blood pressure which will decrease oxygen delivery and perfusion to the already jeopardized cerebral...

Indications for chest physiotherapy techniques

Intermittant lateral turning is indicated for sedated patients and those presenting a neuromuscular disease, or hypoxemia in certain positions, when patients present risk factors for atelectasis or proven sputum retention, or when patients are intubated or tracheostomized. Postural drainage is indicated to eliminate secretions in patients who have excessive production, ineffective cough, cystic fibrosis, or bronchiectasis, in patients who are intubated, and as treatment for atelectasis and...

Physiological changes during sleep

Although sleep results in changes to most physiological systems, attention will be directed to those affecting the respiratory and cardiovascular systems. Respiratory system Although respiratory rate tends to increase during NREM sleep and becomes irregular during REM sleep , minute ventilation falls by 0.5 to 1.5 l min mainly as a result of a decrease in tidal volume. This decrease is most pronounced during REM sleep. The resultant alveolar hypoventilation produces a mean fall of 3 to 10 mmHg...