Commonly Used Drug Infusions

Before even arriving at CWRU-MSA Houston, everyone is assigned a drug card with doses and concentrations of drugs you commonly encounter in the OR. This card is very helpful for an extended period during your training, however, it is just a starting place. One thing that is not featured on the card that you commonly encounter in the OR are drug infusions. This is a basic tutorial that goes over some commonly used infusions, mostly pertaining to Memorial Hermann. It will also cover the concentrations and dilutions that are used for these infusions and how to do a basic setup with an Alaris pump. You may not encounter all of these early on in your training, but this can be a helpful tool to refer back to.

Pay close attention to the units. Most infusions will be run on a mcg/kg/min dose range with a few exceptions.  

Sedatives:

• Propofol: Sedative-hypnotic agent that works through positive modulation of the GABA neurotransmitter.
• TIVA: 100-200mcg/kg/min 
• In these cases, for one reason or another, you are not running any volatile anesthetic. Propofol will generally be the main hypnotic agent making up for the lack of volatile. Dosing range varies on a number of factors including age and what other IV sedative/analgesic agents you are running.
• Mild sedation: 25-75mcg/kg/min.
• This dose range is seen in certain cases such as colonoscopies and EGD’s. At Hermann and the DDC, however, pumps are not used and the drug is titrated by hand.
• Neuro cases: 25-75mcg/kg/min
• In many neuro cases, propofol is run in addition to half a MAC of gas and a narcotic infusion. Necessary for intracranial surgery with necessary management of ICP and spine cases in which the surgeon is using neuro monitoring (SSEP’s & MEP’s).
• Dilution: You can get 50ml or 100ml vials of propofol from the Pixis or pharmacy that come in 10mg/ml concentrations. No need to dilute. Just spike bottle and set to pump.

• Precedex: Alpha-2 agaonist. Used in numerous settings. You will most commonly see it in the OR used for awake fiberoptic intubations, smoothing out the patient emergence, and running as an infusion along with a narcotic and half a MAC of gas during neuro cases (often in cases treating epilepsy where propofol is contraindicated because it hinders surgeon analysis of epileptic foci in the brain).
• Initial Bolus: 1mcg/kg over 10 minutes.
• Infusion: 0.2-0.7 mcg/kg/hr
• Dilution: Precedex usually comes in one of two concentrations: The first is a 50ml bottle from the pharmacy @ 4mcg/ml. No need to dilute this bottle. Just spike bottle as is and hook to the pump. The second is in a 2ml vial @ a concentration of 100mcg/ml (a total of 200mcg per vial). Take these 2 mls and dilute into a 50ml bag of NS to get a final concentration of 4mcg/ml.  

 Pain Control:

• Ketamine: Works really well for pain control, particularly in patients that take chronic pain medications or abuse narcotics. At pain level doses, I have never run into any issues with hallucinogenic side effects. Also works well to bolus the agent at around these same doses.  
• Infusion: 0.2-0.5mg/kg/hr
• Concentration: Can find in the pharmacy in either 10mg/ml, 50mg/ml or 100mg/ml concentrations. For bolus dosing, I generally like a 10mg/ml concentration. For infusions, I recommend diluting down to 1mg/ml in a 50ml or 100ml bag of NS. 

• Remifentanil: Narcotic with a potency approximately 2X that of fentanyl. Virtually no context sensitive half-life. Will NOT provide analgesia following case, in fact, patients may experience hyperalgesia. Good for cases when surgeon needs to perform post-op neuro analysis of patient. Usually run in addition to propofol and half MAC of volatile.
• Infusion: 0.1-0.3 mcg/kg/min
• Dilution: Comes in a powder 1mg/vial. Mix either 1 or 2 mg in a 100ml bag to make a concentration of 10mcg/ml or 20 mcg/ml 

• Sufentanil: Narcotic with a potency 10X that of fentanyl. Has a longer context sensitive half-life than that of remifentanyl and shorter than that of fentanyl. Probably the most commonly used at Hermann because it provides some post-op analgesia. Usually run in addition to propofol and  half MAC of volatile.
• Infusion: 0.1-0.3 mcg/kg/hr
• Dilution:  Comes in a 2ml glass vial at a concentration of 50mcg/ml (a total of 100mcg per vial) Dilute into a 100ml bag of NS to a concentration of 1mcg/ml. Other institutions will have to dilute to a 5mcg/ml concentration so that a 1ml bolus will be the same as a 1ml bolus of fentanyl.

Vasopressors:

In most situations when using vasopressors and anti-hypertensives, you will generally start on the lower end of the dosing range and titrate up as needed.

• Phenylephrine: Primarily alpha agonist activity.
• Infusion: 0.15-0.75mcg/kg/min
• Many institutions are fine with you making a 250ml bag @ 40mcg/ml and hooking up to a 60 dropper IV tubing and titrating with the roller clamp by hand. Don’t try this at Hermann, however, you’ll likely get in trouble.
• Dilution: 10mg into 100ml or 250 ml bag to make either 100mcg/ml or 40mcg/ml concentrations.

• NorEpinephrine: Alpha and beta agonist activity, but more alpha than beta.
• Infusion: 0.05 – 0.5 mcg/kg/min or 2mcg/min – 10mcg/min (this dosing seen more at other institutions).
• Dilution: 1 mg into 100ml bag = 10mcg/ml or 4mg into 250ml bag = 16mcg/ml

• Epinephrine: Alpha and beta agonist activity
• Infusion: 0.05 – 0.5 mcg/kg/min or 2mcg/min – 10mcg/min (this dosing seen more at other institutions). 
• Dilution: 1 mg into 100ml bag = 10mcg/ml or 4mg into 250ml bag = 16mcg/ml

• Vasopressin: Vasopressin is one of the few drugs that regardless of which institution you are in will not be dosed on a per kg basis. Works well in the setting of sepsis, when patients have taken ARB’s or ACE inhibitors on the morning of surgery, and in patients with pulmonary HTN (causes limited pulmonary vasoconstriction in comparison to peripheral vasoconstriction).  
• Infusion -  1 Unit/hr – 4 Units/hr
• Dilution – In many hospitals, you can get a 50ml bag @ 1 Unit/ml concentration from the pharmacy. If not, it will come in a 1cc vial @ 20U/ml. Take 5 ml (a total of 100U) and put into a 100ml bag to make a 1U/ml concentration.

• Dopamine: The function of dopamine is very dose dependent. Below, different infusion rates are labeled with their associated functions.
• Infusion:
• Improved renal function(??): 0.5-2.5mcg/kg/min
• Beta activity: 2.5-10 mcg/kg/min
• Alpha & Beta: 10-20mcg/kg/min
• Dilution: 400mg/250ml, 800mg/250ml, 800mg/500ml – All pre-made bags from pharmacy.

Anti- hypertensives:  

• Nicardipine: Calcium channel blocker. Primarily a vasodilator. Does not depress HR, cardiac contractility or suppress electrical activity in the nodes of the heart. Longer acting than NTG.
• Infusion: 1-4mcg/kg/min
• Dilution: 25 mg into a 250ml bag = 100mcg/ml. Usually pre-made by the pharmacy.  

• Nitroglycerine: Primarily causes venous vasodilation.
• Infusion: 0.5 – 2mcg/kg/min
• Dilution: 50mg in a 250ml bag = 200mcg/ml. Generally in pre-made bottle or bag by pharmacy.

Setting up the Pump:

Reading the pump set up on its own really isn't all that helpful. Take some time to play around with the pump when you are actually in the OR. They are not difficult to use, however, it may take a little time and experience getting used to it. If you can pull this up on your phone, it can be a helpful guide in walking you through the step-by-step process. Not every  institution uses the Alaris but many do and it's a good place to start in learning on how to operate pumps in general.

A Alaris pump that is turned off is pictured below. To power it on, simply hold down the "System On" button that is located near the bottom right hand corner of the screen. You may need to hold it for a few seconds until the screen comes on. This would be a good time to make sure that the pump is plugged in as well. Sometimes it will alarm at you if it is not and the battery reaches a low level.

As the machine powers on, the first screen will ask you if it is a new patient. Press the arrow button located next to the "Yes" icon. After this, it will ask if this is critical care. Again, press the arrow key next to the "Yes" button again. The next screen will prompt you to enter a patient ID. This isn't an important step, so without entering anything press the arrow key at the bottom of the screen that points to the "confirm" button.

At this step, the pump is technically ready for you to start hooking up drugs and programming infusion rates, but first I want to show you a few things that will make life easier before we move on. To start, we are going to switch the pump into anesthesia mode. This mode allows us to access more drug profiles and will not alarm at you if a channel is paused for an extended period. To switch into anesthesia mode, press the "Options" button near the bottom left hand side of the screen. Next, press the arrow button that points to the "Anesthesia Mode" icon. From here, press the arrow key next to the "Enable" icon, followed by the arrow pointing to the "Confirm" icon. This will take you back to the home screen.

One more step until we get to the infusion programming. We are going to want to turn down the alarms volumes. The default setting is quite loud and can be annoying to both you and the surgical team. In turning down the volume, you can still hear it, but it won't be as much of a bother. From the home screen, press the arrow at the bottom of the screen next to the "Audio Adjust" icon. At the next screen, press the arrow button next to the "softer" icon until the volume appears to be at its lowest setting. Once you have done this, press the arrow near the "Main Screen" icon to return to the home screen.

Finally, we are ready to start programming our infusion. There are a number of drugs already programmed in the pump. We will use propofol as our example since it is one commonly used infusion. Programming for other drugs/infusions will essentially be the same with a few subtle differences, so you should be able to use this example in other scenarios.

Begin by pressing the one of the "channel select" buttons on one of the physical pump channels. Either A or B will work, depending on which one you want to start with. Press the arrow key next to "Guardrail Drugs". This will access the drug library already programmed in the pump. You can see a number of drugs in here. To find Propofol, press the arrow key next to the "P-T" icon. The drugs will be organized in alphabetical order. If you don't initially see your drug of choice, you may need to use the "Page up" or "Page down" icons at the bottom of the screen to scroll through your options. Next, press the arrow key next to "propofol." Since this is a commonly used drug at a certain concentration, it is already programmed in the pump and can be seen on the next screen. Some drugs may have multiple options or you may need to manually enter in the concentration. Confirm by pressing the arrow next to the "yes" key.

The pump will then prompt you for the patient weight. Enter is in kg using the number keypad and then press the "next" arrow. The next screen will ask for a VTBI = volume to be infused and the rate at which you want to run the infusion. Use the arrow keys next to each choice to highlight your selection and enter the associated values. For this example, I have entered 100ml VTBI, a common size of propofol vial, at a rate of 50 mcg/kg/min. When ready, hit the "Start" key followed by the "pause" button on the pump channel.

Now the pump will be ready for use as soon as we hook up the IV tubing. An example can be seen below of how to hook up the tubing properly to the pump. Once latched in place, if you press the "Restart" button on the pump channel, the infusion will begin to run at the settings you programmed earlier. Now you're ready to roll.

Note: you can program the pump before or after putting in the IV tubing, the order doesn't really matter. I just chose to program it before placing the tubing in this example.