Category: Critical Care Nursing The first action to increase PaO2 is to increase the FiO2. If the response is unsatisfactory, one can consider increasing the flow rate of supplemental oxygen or using a mask with an oxygen reservoir (i.e., nonrebreather mask).
Category: Critical Care Nursing A decrease in the oxygen saturation of mixed venous blood (SvO2) can contribute to the severity of hypoxemia. This is usually because of inadequate cardiac output, anemia or increased oxygen consumption by body tissues.
Category: Critical Care Nursing Ventilation/perfusion (V/Q) mismatch is the most common cause of hypoxemia and arises when perfusion is maintained in regions that are no longer participating effectively in gas exchange: for example, atelectasis, pneumonia or lung edema.
Category: Critical Care Nursing One issue with pulse oximetry, notably in critically ill patients, is that it takes many seconds for the SpO2 to reflect acute changes in PaO2, including those occurring due to alterations of oxygen administration and/or positive end-expiratory pressure.
Category: Critical Care Nursing Although PaO2 reflects pulmonary function, it must be related to FiO2 when judging oxygenating efficiency. The PaO2/FiO2 ratio is one indicator commonly employed for that purpose and is used to assess lung function.
Category: Critical Care Nursing Moderate hypoxemia must be compensated for by an increase in cardiac output. When that compensatory mechanism is exhausted or when there is concurrent anemia, hypoxia can develop and result in multiple organ failure and cardiac arrest.
Category: Critical Care Nursing Hypoxemia is almost always the result of respiratory failure, but it can also be the result of cardiac abnormalities. A low cardiac output can aggravate hypoxemia via a reduction in oxygen saturation of the mixed venous blood (SvO2).
Category: Critical Care Nursing Tissue hypoxia is a hallmark of shock and is associated with altered cellular metabolism that results in increased blood lactate levels. To avoid confusion, the word hypoxia should not be used to characterize a low PaO2.
Category: Critical Care Nursing Hypoxemia is defined by a significantly low partial pressure of oxygen (PaO2; less than about 75 mm Hg), regardless of the inspiratory oxygen fraction (FiO2). Hypoxemia can be compensated for by an increase in cardiac output.
Category: Critical Care Nursing Oxygen delivery (DO2) to the tissues is determined by cardiac output and the arterial oxygen content, which in turn is determined by the hemoglobin concentration and its oxygen saturation.
Category: Critical Care Nursing Sinus node dysfunction can manifest with sinus bradycardia, sinus pauses or tachycardia-bradycardia syndrome. Asymptomatic sinus bradycardia has not been associated with adverse outcomes and treatment is not recommended.
Category: Critical Care Nursing Abnormalities of the sinus node, atrial tissue, AV nodal tissue or conduction system can cause bradyarrhythmias. Bradyarrhythmias are more common in older patients because of age-related degeneration and fibrosis of the conduction system.
Category: Critical Care Nursing Treatment of torsades de pointes includes discontinuing QT-prolonging agents, correcting electrolyte derangements, administering magnesium and increasing the ventricular rate with isoproterenol or temporary pacing.
Category: Critical Care Nursing Polymorphic ventricular tachycardia can occur in the setting of a normal (< 460 ms) or prolonged (> 460 ms) QT interval. Unstable patients with normal QT interval-associated polymorphic VT require immediate defibrillation.
Category: Critical Care Nursing In addition to antiarrhythmic administration for the treatment of ventricular tachycardia, correction of electrolyte abnormalities and discontinuation of offending agents should be performed concurrently.
