Alarms in Mechanical Ventilation - Low and High Pressure

Understanding Alarms in Mechanical Ventilation

Low Pressure Alarm

  • Definition: This is recognized as a low tidal volume alarm in mechanical ventilation.
  • Key Characteristics:
    • Remember the double l's in "low" which signify a loss of connection.
    • This results in an air leak within the ventilation system.
  • Typical Causes:
    • Cuff Leak: Often due to an improperly inflated cuff that does not create an adequate seal.
    • Endotracheal (ET) Tube Displacement: A situation that can be particularly concerning as it can lead to insufficient ventilation or oxygenation.
    • Disconnection of Tubes: This can occur at various points in the ventilatory circuit, resulting in compromised functionality.

High Pressure Alarm

  • Definition: This alarm is also referred to as the high peaked pressure alarm.
  • Key Characteristics:
    • The letter "h" can be recalled which stands for high blockage, indicating a situation where airflow is obstructed.
    • This obstruction results in increased airway pressure readings.
  • Common Causes of High Pressure:
    • Biting of the ET Tube: Patients may inadvertently occlude the tube with their teeth.
    • Kinks in the Tubing: Physical obstructions can prevent air from passing freely through.
    • Excessive Airway Secretions: Such as mucus plugs that can obstruct airflow.
    • Coughing: A very common action that temporarily increases pressures within the system.
    • Client Fighting the Ventilator: This often appears when patients are waking up from sedation, leading to increased resistance.
  • Serious Causes:
    • Pulmonary Edema: The accumulation of fluid in the lungs which can severely obstruct air exchange.
    • Pneumothorax: A critical condition where air collects in the pleural space, which can exert pressure and collapse lung function.
  • General Implications: High airflow blockage causes more pressure within the system, requiring prompt assessment and intervention.

Case Example

  • Reference from Kaplan:
    • A patient with emphysema undergoing mechanical ventilation presents as restless and agitated.
    • Priority Action:
    • Instruct the patient to allow the ventilator to breathe for them, adapting to the patient’s needs during episodes of agitation and respiratory distress.
  • Common NCLEX Question: Understanding patient responses and priorities related to high pressure alarms in patients with underlying respiratory conditions like emphysema is a focus area for examination.