From the Guidelines
Pressure support ventilation (PSV) can cause hypotension in some patients, particularly when high levels of pressure support are used, as it increases intrathoracic pressure, reducing venous return to the heart and subsequently decreasing cardiac output and blood pressure. This effect is more pronounced in patients who are hypovolemic, have right ventricular dysfunction, or are dependent on venous return for maintaining blood pressure 1. The risk of hypotension is generally higher with higher PSV settings (typically above 15-20 cmH2O) and in patients with pre-existing cardiovascular instability.
Key Considerations
- Patients with hypovolemia, right ventricular dysfunction, or dependence on venous return for blood pressure maintenance are especially vulnerable to PSV-induced hypotension.
- Higher PSV settings increase the risk of hypotension.
- Monitoring of hemodynamic parameters is crucial when using PSV.
Management Strategies
- Start with lower PSV levels (8-10 cmH2O) and titrate gradually.
- Ensure adequate intravascular volume.
- Consider alternative ventilation modes if hypotension occurs.
- Non-invasive positive pressure ventilation, such as CPAP or BiPAP, can be used with caution in hypotensive patients, as it can reduce blood pressure 1.
Physiological Mechanism
The interplay between respiratory and cardiovascular systems is complex, with positive pressure in the thorax impeding blood flow back to the heart, potentially compromising cardiac filling and subsequent output. This mechanism is supported by studies on the effects of positive pressure ventilation on cardiovascular function 1.
Clinical Implications
Given the potential for PSV to cause hypotension, particularly in vulnerable patients, clinicians must be cautious and monitor patients closely. The use of non-invasive positive pressure ventilation, as recommended in the 2016 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure, should be considered with caution in hypotensive patients 1.
From the Research
Pressure Support Ventilation and Hypotension
- The relationship between pressure support ventilation (PSV) and hypotension is complex and has been studied in various contexts.
- A study from 1994 2 found that life-threatening hypotension can occur in patients undergoing emergency intubation and mechanical ventilation, but it did not specifically investigate the role of PSV in causing hypotension.
- Another study from 2010 3 compared the effects of PSV and neurally adjusted ventilatory assist on breathing pattern, patient-ventilator synchrony, and gas exchange, but it did not report any instances of hypotension.
- A study from 1992 4 introduced a new mode of ventilation called volume-assured pressure support ventilation (VAPSV), which combines inspiratory pressure support with conventional volume-assisted cycles, and found that it reduced patient workload and improved synchrony between the patient and the ventilator, but it did not mention hypotension as a potential complication.
- A study from 2008 5 compared patient comfort during PSV and volume controlled-continuous mandatory ventilation, and found that PSV was more comfortable, but it did not investigate the effects of PSV on blood pressure.
- A study from 1989 6 investigated the cardiopulmonary effects of PSV and found that it improved ventilation and reduced respiratory rate, but it did not report any instances of hypotension.
Mechanisms and Associations
- The available evidence does not provide a clear answer to the question of whether PSV can cause hypotension.
- However, it is possible that PSV may affect blood pressure indirectly by improving ventilation, reducing respiratory rate, and increasing mean airway pressure, as reported in the study from 1989 6.
- The study from 1994 2 found that life-threatening hypotension was associated with hypercarbic chronic obstructive pulmonary disease (COPD) and hypoxemic respiratory failure, but it did not investigate the role of PSV in causing hypotension in these patients.