Of what significance is the early history of prematurity? Why? Do you still anticipate problems? Should this patient have a retinal exam preoperatively for retinopathy of prematurity (ROP)? Why/why not? Is the concentration of inspired oxygen a concern in your anesthetic plan? Should this patient receive narcotics?

Is this patient at greater risk for the development of malignant hyperthermia? Why/why not? How can you further determine this? Should the patient have a muscle biopsy? Would you use a clean technique? Why/why not?

She is quite small for her age, so the first thing to be concerned about is failure to thrive; an average 2-year-old should weigh about 12 kg. If she is simply small for her age and has been consistently at the lower end of the growth curve, then reassurance from the pediatrician along with an adequate nutritional history would probably suffice, but it is very possible that with poor intake, she may be anemic and immunodeficient and have other issues that require further medical consultation. She may have retinopathy of prematurity, which has been associated with a history of supplemental oxygen therapy in prematures and many other neonatal factors as well; however, the index of suspicion for severe retinopathy is probably low, because the treatment was of short duration. Nevertheless, it would be reasonable for the ophthalmologist to do a quick exam just to answer the question about the appearance of the fundus so that it can be documented, and it is likely that with this history, an exam would have been done anyway. It would not dissuade me from delivering a routine anesthetic consisting of an F_iO₂ of 0.3–0.4 following 100 % oxygen prior to intubation. Likewise, I would not be concerned about a significant risk of respiratory depression with judicious amounts of opioids, with this history of 2 years of age in an otherwise asymptomatic ex-34 weeker.

Malignant hyperthermia has been associated in the past with strabismus, principally through case reports in the ophthalmology literature, although a higher than background rate (fourfold higher) association with masseter muscle spasm has been described in strabismus patients who underwent anesthetic induction with halothane and succinylcholine. The association between masseter muscle spasm and the subsequent development of malignant hyperthermia remains unclear. I would proceed, therefore, with a routine inhalation induction but nevertheless try to avoid succinylcholine for the more typical reason of its higher incidence of masseter muscle spasm and other possible adverse effects such as rhabdomyolysis or hyperkalemia in children. In addition, many ophthalmologists prefer not to have the sustained extraocular muscle contracture, produced as a side effect of succinylcholine, influence their measurements for the procedure.

What are your considerations for anesthetic induction? Why? Your colleague stops by and suggests pretreating with an anticholinergic? What do you think? Should this patient have been premedicated with an anticholinergic an hour earlier? Is intravenous administration during induction more or less effective for prevention of the oculocardiac reflex? Why/why not?

Is a muscle relaxant necessary for this case? Why? What is your choice of muscle relaxant? Why? Will you use nitrous oxide? Why/why not? Should this patient routinely receive antiemetics? What’s your choice? Why? What are the disadvantages of metoclopramide in a child compared with an adult? Is total intravenous anesthesia with propofol an advantage? Would ondansetron be of any greater benefit? Is dexmedetomidine part of your anesthetic plan? Advantages? Disadvantages?

During surgery, the patient suddenly develops a drop in heart rate from 110 to 54 beats per minute. What is your differential diagnosis? How can you go about treating? What would you do? Why? Why does this happen? What is the specific pathway of this reflex? Does greater anesthetic depth block this reflex? What is a traction test? What is a duction test?

My principal consideration for this child, who is certainly small for her age but in reasonable health according to her vital signs and hematocrit, is her separation/preoperative anxiety. This can be dealt with by anxiolytic premedication with or without a parent-present induction. The premedication is more likely to be anxiolytic than the presence of the parent, although there is much variation. Moreover, many parents wish to be present for a variety of reasons beyond “reassurance,” such as curiosity and education, and these may be very reasonable because ultimately satisfying these needs will inform future decisions and may be helpful for siblings as well. However, parents should not feel compelled to go into the operating room or participate in the parent-present induction if they do not wish to do so. Many in the past have felt that an anticholinergic premedication in the setting of strabismus surgery is required to decrease the incidence of the oculocardiac reflex. When working with experienced surgeons, the bradycardia of the oculocardiac reflex is most rapidly treated by asking the surgeon to stop the traction on the extraocular muscle. If an anticholinergic is needed to treat the bradycardia, it can be administered intravenously at that time. Most patients, however, do not experience the bradycardia of the oculocardiac reflex in the hands of a skilled surgeon, so their routine exposure to an anticholinergic is not necessary.

A muscle relaxant is not necessary for this case, as long as the patient is well anesthetized and motionless. Movement under the microscope will be magnified, and there is the possibility of significant compromise of the surgical procedure and injury to the patient. Surgeons often have a preference for operating with or without the administration of a neuromuscular blocking agent and will often make that part of their preoperative discussion with the anesthesiologist. The most important thing, however, is consistency of anesthetic technique with regard to the surgeons’ caliper measurements for muscle resection and recession. The choice of muscle relaxant will depend on the anticipated length of the surgery (i.e., the number of muscles). Pancuronium, with its associated tachycardia, may be a very reasonable choice for this particular procedure. Neuromuscular blockade should be monitored carefully because of the echothiophate treatment. I would use nitrous oxide as part of the anesthetic technique, with only a minor concern about its possible contribution to perioperative nausea and vomiting (PONV), which is likely to occur in any event with this patient because of the association of PONV with strabismus surgery. Prophylactic antiemetic administration is very reasonable given the high association of strabismus surgery with PONV. For years, droperidol was routinely administered to strabismus surgery patients, but now there is concern about its effect on cardiac conduction and its possible contribution to Torsades, an extremely rare event which nevertheless resulted in a “Black Box” warning from the FDA which effectively stopped the use of droperidol as an antiemetic. Other antiemetics include ondansetron, a selective 5-HT3-receptor antagonist which blocks serotonin, both peripherally on vagus nerve terminals and centrally in the chemoreceptor trigger zone. Metoclopramide can also be used, but is associated with a higher incidence of tardive dyskinesia in children than in adults, although these are typically in larger dose ranges than those administered by anesthesiologists. Propofol-based TIVA may have some advantages in that it has an antiemetic effect and would also allow avoidance of the use of potent inhalation anesthetic agents. Its antiemetic effect, however, may be of questionable duration into the postoperative period, so a more sustainable strategy might involve the use of ondansetron, dexamethasone, and possibly metoclopramide.