Useful Pediatric Anesthesia Equations
You are driving to the hospital, en route to doing a pediatric anesthetic on a 2-year-old that will require an endotracheal tube. You are thinking through the case in advance. What can you do to plan your anesthetic?
During my anesthesia training at Stanford, Dr. Stanley Samuels, the co-author of Anesthesiologist’s Manual of Surgical Procedures, by Jaffe and Samuels, (Fourth Edition, 2009, Lippincott Williams and Wilkins), taught me a series of equations regarding pediatric anesthetics. These equations are listed below, and provide time-tested guidelines to help the anesthesiologist select the correct endotracheal tube size, the correct intravenous infusion rate, and to estimate a child’s weight and dosing requirements of intravenous drugs.
As Dr. Samuels told me, “You can be driving in toward the hospital, knowing that your patient is 2 years old, and plan details of your anesthetic in advance.” The equations are as follows:
- The endotracheal tube size = age/4 + 4
- Estimating a child’s weight:
Newborn = 3 kg
1-year-old = 10 kg
Add 2 kg per year up until the age of 6 years.
- The IV rate per hour = 40 ml/hr (first 10 kg) + 20 ml/hr (second 10 kg) plus 10 ml/hr for every extra 10 kg
- Dosing of IV medications:
A 7-year-old takes ½ of adult dose
A 1-year-old takes ¼ of adult dose
A newborn takes 1/10 of adult dose
For your 2-year-old patient, you will prepare a 4.5 ID endotracheal tube, expect the patient to weigh about 12 kilograms, plan a maintenance IV rate of 45 ml/hour, and expect that all drug doses (including emergency resuscitation drug doses) will be in a range of slightly more than ¼ of typical adult doses.
Published in September 2017: The second edition of THE DOCTOR AND MR. DYLAN, Dr. Novak’s debut novel, a medical-legal mystery which blends the science and practice of anesthesiology with unforgettable characters, a page-turning plot, and the legacy of Nobel Prize winner Bob Dylan.
In this debut thriller, tragedies strike an anesthesiologist as he tries to start a new life with his son.
Dr. Nico Antone, an anesthesiologist at Stanford University, is married to Alexandra, a high-powered real estate agent obsessed with money. Their son, Johnny, an 11th-grader with immense potential, struggles to get the grades he’ll need to attend an Ivy League college. After a screaming match with Alexandra, Nico moves himself and Johnny from Palo Alto, California, to his frozen childhood home of Hibbing, Minnesota. The move should help Johnny improve his grades and thus seem more attractive to universities, but Nico loves the freedom from his wife, too. Hibbing also happens to be the hometown of music icon Bob Dylan. Joining the hospital staff, Nico runs afoul of a grouchy nurse anesthetist calling himself Bobby Dylan, who plays Dylan songs twice a week in a bar called Heaven’s Door. As Nico and Johnny settle in, their lives turn around; they even start dating the gorgeous mother/daughter pair of Lena and Echo Johnson. However, when Johnny accidentally impregnates Echo, the lives of the Hibbing transplants start to implode. In true page-turner fashion, first-time novelist Novak gets started by killing soulless Alexandra, which accelerates the downfall of his underdog protagonist now accused of murder. Dialogue is pitch-perfect, and the insults hurled between Nico and his wife are as hilarious as they are hurtful: “Are you my husband, Nico? Or my dependent?” The author’s medical expertise proves central to the plot, and there are a few grisly moments, as when “dark blood percolated” from a patient’s nostrils “like coffee grounds.” Bob Dylan details add quirkiness to what might otherwise be a chilly revenge tale; we’re told, for instance, that Dylan taught “every singer with a less-than-perfect voice…how to sneer and twist off syllables.” Courtroom scenes toward the end crackle with energy, though one scene involving a snowmobile ties up a certain plot thread too neatly. By the end, Nico has rolled with a great many punches.
Nuanced characterization and crafty details help this debut soar.
Click on the image below to reach the Amazon link to The Doctor and Mr. Dylan:
Learn more about Rick Novak’s fiction writing at ricknovak.com by clicking on the picture below: