A significant number of our critical care patients are dependent on vasoactive drugs, so it is worth reviewing the process for managing these infusions during inter-hospital transfers.
The priming volume of the distal lumen of a central line is 0.44mls. Therefore an infusion running at 10mls / hour could take approximately 3 minutes to reach the patient if started de novo. The half-life of inotropes such as adrenaline and noradrenaline is short, approximately 1 minute. This leaves the patient vulnerable to a period of hypotension. Corrective bolusing of vasoactive drugs is not recommended as it can lead to large, and potentially detrimental, swings in blood pressure. Therefore a smooth transition between syringe pumps is recommended to maintain haemodynamic stability.
There are a number of different methods for double pumping but one suggested protocol is as follows:
- Leave infusion number 1 running at its current rate (100%)
- Commence infusion number 2 at 50% of the rate of infusion number 1
- Wait for a small kick in blood pressure to indicate that the second infusion is reaching the patient. This can be up to but should not exceed SBP 20mmHg
- Immediately increase infusion number 2 to 100% (the current rate of infusion 1) and reduce infusion number 1 back to 50%.
- Reduce infusion 1 back to zero incrementally over a few minutes ensuring that BP doesn’t drop.
Tips and tricks
- Avoid the use of a 3-way tap if you have enough ports to manage without. Three-way taps increase the complexity of the process and the likelihood of an error. No matter how intelligent you think you are, 3-way taps have a habit of embarrassing you. If you really must use a 3-way tap make sure both taps are “on” to the patient during the process and then make sure the correct tap is left “on” at the end.
- Dedicate a member of the HEMS team to the double pumping process and avoid being interrupted during it.
- Use a dedicated line for vasoactive drugs to prevent inadvertent bolusing
- Label the line and the syringe driver clearly to prevent confusing the vasoactive drug with sedation (which can be, and often is, bolused)
- If you are about to embark on a long transfer you may want to replace a single strength vasoactive drug with double strength. Take this into account when double pumping. If infusion 2 is double strength it will need to be started at 25% of infusion 1 and then increased to 50% once the BP kick is seen.
- Be patient. Depending on the infusion rate and the dead space in the catheter lumen, the process can take several minutes. It is worth taking the time to do it smoothly rather than trying to speed it up by increasing infusion rates or bolusing.
Management of the changeover of inotrope infusions in childrenIntensive and Critical Care Nursing 2004 ArinoChangeovers of vasoactive drug infusion pumps impact of a quality improvement programCritical Care 2007 Argaud