English (United States)
Learn more about Clinical Skills today! Standardize education and management competency among nurses, therapists and other health professionals to ensure knowledge and skills are current and reflect best practices and the latest clinical guidelines.
To increase the patient’s cooperation and decreased his or her anxiety, explain that he or she will be undergoing a test involving changing the ventilator settings (breath hold).
Don appropriate personal protective equipment (PPE) based on the patient’s signs and symptoms and indications for isolation precautions.
A patient’s pulmonary system can be monitored for early signs of pathophysiologic changes using the measurements of respiratory mechanics. In mechanically ventilated patients, changes in respiratory mechanics may occur abruptly, or they may reveal slow trends in respiratory function.2 Detection of alterations in pulmonary physiology and lung mechanics can help guide the respiratory therapist (RT) in the clinical management of the mechanically ventilated patient.
Normal compliance in a nonmechanically ventilated patient is 60 to 100 ml/cm H2O. Low compliance of 25 to 30 ml/cm H2O is common with pulmonary edema, interstitial lung disease, lung hyperinflation, pleural disease, obesity, bronchial intubation and ascites.2
Dynamic compliance (CD) measures both lung compliance and airway resistance (Raw). CD is not an accurate assessment of how compliant the lungs are because it measures airflow through the airway as well as the ventilator circuit.1 The patient’s lung and chest wall elastic recoil, Raw, endotracheal (ET) tube, and the patient-ventilator circuit all influence the CD.1
Static compliance (CS) is a more precise indicator of lung compliance because it is measured when no airflow is in the airway or the patient-ventilator circuit. Obtaining an accurate assessment of CS requires patient-ventilator synchrony and the absence of patient effort.1 The normal CS for intubated, mechanically ventilated patients is 70 to 100 ml/cm H2O.1 Decreasing CS may be caused by pneumonia, atelectasis, consolidation, pneumothorax, pleural effusion, pulmonary edema, and ascites.1
The normal Raw in a nonmechanically ventilated patient is 0.6 to 2.4 cm H2O/L/sec.1 The normal Raw in an intubated, mechanically ventilated patient is 5 to 10 cm H2O/L/sec.2 Secretions, bronchospasm, cuff herniation, airway compression, and kinking, biting, or plugging of the ET tube produce increased Raw.
Lung problems can be identified easily by monitoring the changes in peak inspiratory pressure (PIP), plateau pressure (Pplat), and the difference between the PIP and Pplat. If PIP and Pplat are both increasing with no change in the delivered tidal volume (VT) and the difference between them is constant, then the CS is decreasing. If the PIP increases along with the difference in CD and CS, then Raw is increasing. The CD decreases when CS decreases or Raw increases.1
A ventilator with the capability to display PIP, positive end-expiratory pressure (PEEP), flow rate, and VT is used to calculate compliance and resistance. Some ventilators can display the values graphically.
Click here for a list of supplies.
Rationale: Activation of the inspiratory pause (hold) on most ventilators automatically closes the inspiratory and expiratory valves at end inspiration. The pressure falls from PIP to a lower Pplat.
Keep Pplat below 30 cm H2O to avoid ventilator-induced lung injury.1
Rationale: Gas trapped in alveoli at end expiration may cause auto-PEEP.
Cookies are used by this site. To decline or learn more, visit our cookies page.