Latest posts by the anesthesia consultant (see all)
You are anesthetizing a 7-year-old male for middle ear surgery. At hour two of the case, the heart rate rises to 130 beats per minute, the respiratory rate is 36 breaths per minute, and the nasal temperature is 38.5 degrees Centigrade. What do you do?
Discussion: Because you are a brilliant anesthesiologist, you make a diagnosis of hyperthermia. The patient’s anesthetic drugs include sevoflurane, but not succinylcholine. The circulating nurse is looking over your shoulder, and says, “My God, it’s malignant hyperthermia! I just read about that in a nursing journal last week. Should I start mixing up the dantrolene? Should I get the orderlies to bring a tub of ice in here?”
Because you are a brilliant doctor, you reach over and turn off the Bair hugger, you turn off the warming blanket in the mattress, and you remove all the blankets covering the child. You examine the patient, and confirm that he is warm and sweaty. His pulse is rapid and otherwise feels normal. The cardiac and pulmonary exams are normal.
You turn your attention to the other monitors. The oximeter reads 100%, and the blood pressure is 100/60. The end-tidal gas monitor shows the measured end-tidal CO2 concentration is 28 mm Hg.
Your nursing colleague tells the surgeon that the patient is hyperthermic, and the surgeon says to you, “What the hell is going on? Should I stop operating? Should they bring the malignant hyperthermia cart in here?”
Before panic sets in, you reassure them. You tell them that malignant hyperthermia (MH) is a disorder of hypermetabolic state, which creates increased CO2 production and heat from skeletal muscle. In MH, if ventilation is controlled at a constant rate, the end-tidal CO2 will increase. In this patient, the spontaneous respiratory rate has increased, and your spirometer reading indicates that the minute ventilation is 200 ml X 36 breaths per minute = 7.2 liters per minute. This patient is hyperventilating, and has a low end-tidal CO2.
In MH you expect a combined metabolic and respiratory acidosis, due to massive CO2 production. You do not have an arterial blood gas on this patient, but the end-tidal CO2 of 28 argues against respiratory acidosis. You are aware that measured end-tidal CO2 may be much lower than the arterial pCO2 when there is high dead space or high pulmonary shunting, but you have no reason to expect either in this healthy young patient. The low end-tidal CO2 does not fit with fulminant MH.
You tell the surgeon and nurse that you could confirm the patient’s acid-base status by measuring an arterial blood gas, but your first move is to discontinue all the heating devices and blankets and see if the temperature and pulse rate decrease. You inform the surgeon that your diagnosis is passive hyperthermia due to excessive patient heating, and ask him to continue operating.
In the next thirty minutes, the heart rate drifts down to 110, and the temperature decreases to 37.2. The respiratory rate is 24 breaths per minute, and the end-tidal CO2 is 35. The surgery finishes, the patient is awakened and the tracheal is extubated. In the recovery room, the patient is reunited with his mother, and he has a normal temperature.
How common is malignant hyperthermia? Miller’s Anesthesia (2010, p 1181) quotes an incidence of 1:62,000 anesthetics. It is important that we are knowledgeable about the disease, and how to recognize and treat it, but it is the ultimate “low frequency, high impact” disease for an anesthesiologist. Patients can die if dantrolene and the other MH protocol therapies are not utilized when MH is diagnosed. According to Miller, even treated MH has a mortality which approaches five percent.
On the other hand, passive hyperthermia is more common, and does occur in circumstances such as those described in our patient above (Miller’s Anesthesia, 2010, p 1548). There is very little published about the incidence of passive hyperthermia, but be aware that it exists. Make the right diagnosis, and don’t feed dantrolene or other zebra food to hyperthermic horses.
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: