Ice sterile slush reduces the incidence of oculocephalic reflex during pediatric strabismus surgery
Myron Yaster MD
A gentle giant in the pantheon of the Johns Hopkins Department of Anesthesiology and Critical Care Medicine (ACCM), Dr. Tommy Toung, died about 2 weeks ago. He was an extraordinary physician, neuro-anesthesiologist, clinician scientist, who continued to work in the labs well into his official retirement. He shaped the culture of ACCM and will be sorely missed. I was thinking about him as I read today’s article about taming the oculocardiac response during pediatric strabismus surgery. Many, many years ago Tommy did an interesting experiment that, is one of the few, I think he never published. In that experiment he placed ECG electrodes on patients and on the attending anesthesiologist and monitored both during induction of anesthesia. Interestingly, it was the attending who developed tachyarrhythmias with occasional, as I remember it, ST depressions during induction! I think that’s when I started taking a daily baby aspirin! For those who had the good fortune of knowing him, we will miss you Tommy. Myron Yaster MD
Original article
Xin Qi, Fei Zou, Xin Wei, Ying Wu, Lijun Cao, Junmei Xu, Yulong Cui. Effect of Ice Slush on Reducing the Oculocardiac Reflex During Strabismus Surgery. Anesth Analg. 2023 Jan 1;136(1):79-85. PMID: 36322461
Beep, beep, beap, beep…beep………beep……..beep……………beep…………….. We’ve all experienced a patient who developed significant bradycardia during strabismus surgery. As you simultaneously tell the surgeon to release traction on the eyeball and its muscles, you open your Pedi Crisis app, find the Bradycardia event tab and treat. Is there a better way? Can this reflex arc be prevented prophylactically?
Strabismus surgery is amongst the most common pediatric surgical procedures. Surgical traction of the extraocular muscle during surgery occasionally causes abrupt bradycardia and other dysrhythmias by triggering the oculocardiac reflex (OCR).(1,2) In today’s PAAD, we review a paper by Qi et al.(1) who wondered if this reflex arc can be prophylactically interrupted by using an ice slush to the eye after the induction of anesthesia and BEFORE surgery.
“Ice slush was made from sterile normal saline, which is usually used in cardiopulmonary bypass heart surgery as a cardioprotective agent. The sterilized packaged saline was stored at −20°C until it was frozen into ice. Then, the package was opened, and the iced saline was placed on a sterile operating table. It was crushed with a sterile hammer and gradually became slush as the temperature increased. The complete process was performed under sterile condition. After induction and stabilization of vital signs, the assistant placed the icey slush solution in both the superior and inferior fornical conjunctiva of patients for 5 minutes and covered the cornea with wet cotton pads for protection”.(1) The control group had simple sterile saline applied in the same fashion. The authors found a dramatic decrease in the oculocardiac reflex and its severity in the ice saline slush group. 7 of 29 patients (24.1% [95% CI, 10.3–43.5]) in the icey saline slush group developed a fall in heart rate compared to 17 of 29 patients (58.6% [95% CI, 38.9–76.5]) in the control group.
How does the oculocephalic reflex arc work? “The fifth cranial nerve, the trigeminal nerve is responsible for transmitting sensations from the head and face. The afferent reflex starts from the ciliary nerve to the ciliary ganglion, then to the ophthalmic division of the trigeminal nerve, and ends with the trigeminal sensory nuclei near the fourth ventricle. Meanwhile, the efferent reflex is by the vagus nerve to the heart.”(1,2) The authors speculate that the ice saline slush “rapidly decreases the temperature of the ciliary nerve, rendering it partially paralyzed and inhibiting subsequent sensation transmission”.(1)
Because this is a novel technique, when any of you try it in your practice please let me know your experiences and I will publish in a future PAAD.
References
1.Qi X, Zou F, Wei X, Wu Y, Cao L, Xu J, Cui Y. Effect of Ice Slush on Reducing the Oculocardiac Reflex During Strabismus Surgery. Anesth Analg 2023;136:79-85.
2.Ha SG, Huh J, Lee BR, Kim SH. Surgical factors affecting oculocardiac reflex during strabismus surgery. BMC Ophthalmol 2018;18:103.