From the Guidelines
A falsely elevated respiratory rate on a ventilator is typically caused by auto-triggering, which occurs when the ventilator incorrectly detects a patient breath, and should be addressed by checking for water in the ventilator circuit, adjusting sensitivity settings, and examining for leaks in the circuit or around the endotracheal tube cuff. To address this issue, first check for water in the ventilator circuit and drain it if present, as this can cause auto-triggering 1. Next, adjust the sensitivity settings on the ventilator by decreasing flow or pressure trigger sensitivity, as this can help reduce the likelihood of auto-triggering. Examine for leaks in the circuit or around the endotracheal tube cuff and repair them, as leaks can also cause auto-triggering. If the patient has significant air trapping or auto-PEEP, consider increasing expiratory time or decreasing respiratory rate settings, as this can help reduce the risk of auto-triggering 1. Cardiac oscillations can also cause auto-triggering, especially in small patients; in these cases, try changing the ventilator mode or adjusting trigger settings. Double-checking that the ventilator settings match the patient's needs is essential, as inappropriate settings can lead to patient-ventilator asynchrony. These false readings are concerning because they can lead to inappropriate ventilator adjustments and potentially harmful respiratory support. Always verify the actual respiratory rate by clinical observation of chest movements and auscultation when the ventilator reading seems questionable.
Possible Causes of Auto-Triggering
- Water in the ventilator circuit
- Leaks in the circuit or around the endotracheal tube cuff
- Significant air trapping or auto-PEEP
- Cardiac oscillations
- Inappropriate ventilator settings
Steps to Address Auto-Triggering
- Check for water in the ventilator circuit and drain it if present
- Adjust the sensitivity settings on the ventilator by decreasing flow or pressure trigger sensitivity
- Examine for leaks in the circuit or around the endotracheal tube cuff and repair them
- Consider increasing expiratory time or decreasing respiratory rate settings if the patient has significant air trapping or auto-PEEP
- Change the ventilator mode or adjust trigger settings if cardiac oscillations are suspected
- Double-check that the ventilator settings match the patient's needs to prevent patient-ventilator asynchrony.
From the Research
Ventilator Giving Falsely Elevated Respiratory Rate
- The issue of a ventilator giving a falsely elevated respiratory rate can be related to various factors, including the patient's condition, the ventilator settings, and the monitoring equipment used 2, 3.
- Studies have shown that respiratory rate can be affected by factors such as midazolam administration, which can cause respiratory depression, leading to changes in respiratory rate and other respiratory parameters 3, 4, 5.
- In one study, midazolam administration was found to increase respiratory rate by an average of 10.3% ± 4.7% within 15 minutes of administration, while also decreasing minute ventilation and tidal volume 3.
- Another study found that midazolam attenuated the increases in oxygen consumption, heart rate, and systemic blood pressure observed during chest physical therapy, and also reduced minute ventilation and respiratory rate 4.
- The accuracy of respiratory rate assessment by emergency nurses has also been studied, with results showing that formal assessments may be more accurate than spot assessments, particularly for bradypnea 6.
- Capnography monitoring during intravenous sedation with midazolam has also been assessed, with results showing alterations in end-tidal carbon dioxide (ETCO2) values and respiratory rate 5.
Possible Causes of Falsely Elevated Respiratory Rate
- Midazolam administration 3, 4, 5
- Ventilator settings 2
- Monitoring equipment issues 2, 5
- Patient's condition, such as respiratory depression or distress 3, 6, 5