Pediatric Quick Guide

This is a brief guide that is by no means a comprehensive review of pediatric anesthesiology. It should merely be used as a starting point if you are new to pediatric anesthesia or need a quick refresher if it has been some time since your last pediatric cases. Let’s get started.

Patient Weight

A good number of things in pediatrics are weight based. It is important to find out the patient’s weight as soon as possible, as it will greatly help you in setting up for the case. It can clue you in to what size airway device you will use, doses of drugs to draw up, how to set the ventilator, and how to properly manage the patient’s fluids. You may not always have access to the patient’s weight prior to setting up the room, but if you know his or her age, you can usually make a pretty close estimate using the following equation:

Weight (kg) = ((age in years)x2)+9

What if your patient is under 1 year of age? This is a valid question and the equation doesn’t really work in these situations. Below is a list of correlating ages in months and their associated weight. There really isn’t a good way to remember these, you just have to memorize them. As with the equation above, it may not always be entirely accurate, but it provides a good starting point for your room set up.

New Born = 3.5kg

3 months = 6kg

6 months = 8kg

9 months = 9.5kg

12 months = 10kg

Airway Devices

Now that we have a good idea about how much our patient weighs, we can choose a proper airway device. As with adults, this will vary depending on what type of case you are doing. There are a wide variety of ETT and choosing the correct size is very important. The following equations will help determine what we need to use. In addition to this, sometimes the package will be labeled with the appropriate age or weight.

Cuffed ETT size = ((Age/4) +4) – 0.5

Uncuffed ETT size = (Age/4) +4

Most of the time at Memorial Hermann, you will be using a cuffed tube. At Hermann, the staff will expect that you have ready a half size above and below the predicted size, just in case. Do not open the ETT until you get instructor approval, unless you feel confident in your size choice.

Again, you’ll notice that this equation doesn’t really work for ages under 2 years old. Below are the correlating ages and weights for children under 2.

Premie = 2.0

Term New Born = 2.5

1-6 months = 3.0

6-18 months = 3.5 -4.0

18-24 months = 4.0-4.5

Whichever ETT size you decide on, secure at a depth of 3 x (ETT internal diameter)

Choosing a properly sized blade can be just as important as choosing the correct size ETT. Different attendings sometimes will have different preferences, and there isn’t always a correct choice. This will give you a starting point until you decide which blades you are most comfortable with.

Up to 3 months = Miller 0

3-18 months = Miller 1

18 months – 3 years = Mac 1 or Wisc 1.5 or Miller 1.5

3-5 years = Mac 2 or Wisc 1.5 or Miller 1.5

>5 years = Miller 2 or Mac 2-3

Most of the time with LMA’s, the proper weight range is listed on the package. With different manufacturers, I’m sure this isn’t always the case. Below is a table showing how to properly choose an LMA size.

LMA Size	1	1.5	2	2.5	3	4	5
Weight (kg)	0-5	5--10	10--20	20-30	30-50	50-70	70-100

Common Medication Doses

In most instances, at least for outpatient surgery, pediatric patients will present to the OR without an IV. Unlike adult patients, it is not something that they can tolerate in the pre-op holding area. Before starting an IV, you have a few options for mask induction. Adding different smell flavors to the mask can be very helpful (cherry, grape, strawberry, etc.)

• 70% O2 and 30% N20 – Have the patient breathe this while you start the IV. They will not be completely asleep, but will be sedated/more relaxed. Usually works best for slightly older children that tolerate the mask well and can tolerate some pain from the IV.
• 70% O2 and 30% N20, slowly work up on Sevo up to 8% on dial – Will eventually put patient completely asleep before starting the IV. BMV support may be needed when asleep. Again works well in children that don’t fight the mask being placed on his or her face.
• 70% O2 and 30% N20, Sevo set at 8% on dial – Will quickly get patient completely off to sleep. Works well for patient that are combative when mask is placed on face.
• 100% O2 with Sevo turned to 8% on dial – also quickly works to put patient to sleep. Sevo doesn’t have sweet smell, like N20, so patient often fights mask away.

Premedication – These drugs can be very helpful in making for a smooth transition into the OR and performing a mask induction. Many are taken by mouth since no IV is often available.

• Midazolam – 0.5mg/kg PO, 0.1mg/kg IV
• Ketamine – 2-3mg/kg IM

Commonly used IV meds in the OR –

• Propofol – 2-3mg/kg
• Lidocaine – 1mg/kg (Many people do not give lidocaine upon induction)
• Fentanyl – 1-2mcg/kg
• Rocuronium – 0.5-1mg/kg

• Decadron – 0.1mg/kg = antiemetic; 0.5mg/kg – airway edema
• Zofran – 0.15mg/kg
• Toradol – 0.5mg/kg
• Ofirmev – 10-15mg/kg
• Morphine – 0.05-0.1mg/kg   

               

• Neostigmine – 0.03-0.07mg/kg
• Glycopyrolate – 0.01mg/kg   

   

• Ancef = 30mg/kg q6
• Vancomycin = 15mg/kg q12

Emergency Drugs – In some institutions, it is common practice to have these drugs drawn up in their proper amounts for each case. Others just prefer that they are available. Regardless, I suggest that when starting out that you have the doses calculated out and know exactly how much volume of each to give in an emergency situation. Being in an emergency situation in pediatrics can be stressful enough as it is without having to do math in your head on the fly.

• Succinylcholine – 1-2mg/kg IV, 4mg/kg
• Generally we try to avoid sux in pediatrics because it can cause associated bradycardia and can trigger hyperkalemic cardiac arrest in patients with undiagnosed muscular dystrophy.
• Atropine  - 0.01-0.02mg/kg IV, 0.02-0.03mg/kg IM
• Epinephrine - .01mg/kg = vasopressor, .03-.3mg/kg = Cardiac arrest  

Vent Settings

At Memorial Hermann when manually ventilating the patient, you will most commonly use Pressure Control Mode. You will adjust the pressure accordingly to deliver tidal volumes in the range of 6-10ml/kg for the patient. This is generally safer than using Volume Control Mode, in which it you may accidentally deliver a larger than intended tidal volume and pressure, causing damage to the lungs. Pressure Support mode can also be very helpful.

Fluid Management

Being that some pediatric patients have such small circulating blood volumes, close attention must be paid to managing fluids. Just as in adults, similar equations can be used to estimate circulating blood volumes and allowable blood loss.

Circulating Blood volume:

                Preemie: 100ml.kg

                Term New Born: 90ml/kg

                6 months: 80ml/kg

                1 year: 75ml/kg

                Teens = 65-70ml/kg

Allowable blood loss = CBVx(((Hct-pre)-(Hct-post))/(Hct-pre))

At Memorial Hermann, all fluids are managed using an Alaris pump. This is an extra safety precaution to ensure that you don’t accidentally give your patients too much fluid. Once the IV is started and connected, a 10ml/kg bolus is usually given to combat the hypotension associated with beginning a general anesthetic. Throughout the case, you may give more of these boluses to help treat hypotension.  

Following initial blood loss, fluid is maintained using the 4-2-1  hourly rule in addition to closely following blood loss and urine output.

4-2-1 hourly maintenance:

                4ml/kg for first 10kg

                2ml/kg for second 10kg

                1ml/kg thereafter

For PRBC’s, 10ml/kg will raise the hematocrit by about 3%.


Table Setup at Memorial Hermann

PEDIATRIC GETA SETUP

Drug cart setup for pedi GETA

Alright so now things get a little more tricky. Some of you will do pedi cases pretty early on and the setup is quite different. In most instances you will be asked to prepare syringes and get drugs out but to not draw anything up. The main difference in pedi is that you use a syringe that gives an appropriate single dose for the patient and you always make an epinephrine bag/syringes. Here are the contents of a GETA pedi drug setup.

1. Atropine - comes in this box from the cassette. Just have it out and on the table.
2. Epinephrine in a 100 cc NS bag. Epi comes 1 mg/ml and is diluted to 10 mcg/ml. Then you will draw it up in a 1 cc syringe and a 3 cc syringe (unless you have a small, small child in which case 1 cc syringe only, will do).
3. Epi - 1 cc syringe.
4. Propofol - 10 cc syringe. Again, it can be done in any syringe and the choice is based on the size of the patient and the dose of the drug. Don't worry, you will learn this.
5. Fentanyl - 3 cc syringe. Same "rule" as propofol
6. Rocuronium - 3 cc syringe. Repeat?

Your first days in pedi will be a little overwhelming and the setup and drugs are a big part of that. The idea is to draw up only the amount you would need for a single dose for the patient as to avoid overdosing them. For now this is slightly above and beyond for you all, don't stress.