From the Guidelines
Chest wiggling during mechanical ventilation is typically a sign of patient-ventilator asynchrony, which should be addressed promptly to improve patient comfort, reduce work of breathing, and optimize ventilation and oxygenation. This asynchrony can be caused by various factors, including auto-PEEP, inadequate flow rates, or inappropriate trigger sensitivity, as noted in studies such as 1 and 1. To address this issue, it is essential to assess the patient's respiratory needs by evaluating the respiratory rate, tidal volume, and flow rate, and adjust the ventilator settings accordingly.
Some key considerations include:
- Adjusting the ventilator sensitivity to better detect the patient's breathing efforts
- Evaluating for possible causes of asynchrony, such as auto-PEEP or inadequate flow rates
- Considering temporary increases in sedation using medications like propofol or dexmedetomidine if the asynchrony is causing patient distress, as suggested by general medical knowledge
- Assessing for pain, anxiety, or respiratory distress if the patient is fighting the ventilator
- Potentially changing the ventilation mode from volume-controlled to pressure support to help synchronize the patient's breathing pattern, as noted in 1
The most recent and highest quality study, 1, published in 2016, provides guidance on the ventilatory management of acute hypercapnic respiratory failure in adults, emphasizing the importance of addressing patient-ventilator asynchrony. By following these steps and considering the patient's individual needs, healthcare providers can help resolve asynchrony and improve patient outcomes.
From the Research
Patient-Ventilator Asynchrony
- Patient-ventilator asynchrony occurs when the ventilator output does not match the efforts of the patient, contributing to excess work of breathing, lung injury, and mortality 2.
- Asynchronies are categorized as trigger (breath initiation), flow (delivery of the breath), and cycle (transition from inspiration to expiration) 2.
- Causes for patient-ventilator dyssynchrony include both patient factors (abnormalities of respiratory drive and abnormal respiratory mechanics) and ventilator factors (triggering, flow delivery, breath termination criteria, the level and mode of ventilator support, and imposed work of breathing) 3.
Detection and Monitoring
- Clinicians should be skilled at ventilator waveform analysis to detect patient-ventilator asynchronies and make informed ventilator adjustments 2.
- Careful analysis of ventilator waveforms (pressure-time, flow-time) allows for more precise definition of the underlying cause of patient-ventilator dyssynchrony 3.
- Monitoring patient-ventilator interaction is mandatory in spontaneously breathing patients to understand the type of asynchrony and improve the adaptation of the ventilator to the patient's needs 4.
Clinical Implications
- Patient-ventilator asynchrony may be associated with longer duration of mechanical ventilation, higher ICU mortality, and higher hospital mortality 5.
- Asynchronies are relatively frequent during mechanical ventilation in critically ill patients and are associated with poor outcomes 4.
- Reducing tidal volume during pressure-support ventilation can improve patient-ventilator synchrony by reducing ineffective triggering events without decreasing tolerance 6.
Interventions
- Interventions involving MV mode, tidal volume, and pressure-support level can reduce patient-ventilator asynchrony 5.
- Sedation protocol, sedation depth, and sedation with dexmedetomidine rather than propofol may also be associated with reduced patient-ventilator asynchrony 5.
- Reducing pressure support or inspiratory duration to reach a tidal volume of about 6 ml/kg predicted body weight can eliminate ineffective triggering in two-thirds of patients with weaning difficulties and a high percentage of ineffective efforts 6.