To the Editor:—
I enjoyed reading the Special Article in the July 2003 issue of Anesthesiology, “Succinylcholine and the Open Globe,” by Vachon et al. 1My concern is with their comment, “To follow the dictum ‘primum non nocere,’ we thus avoid succinylcholine.”
Their review is thorough, starting with the 1952 introduction of succinylcholine. They mention the anecdotal comments by ophthalmologists, relating loss of vitreous after succinylcholine, reminding us that there are no actual case reports of this problem. The authors mention the Libonati retrospective study, in which they reviewed 73 open globe surgeries, all induced using succinylcholine, and there were no incidents of vitreous extrusion. Libonati et al. 2then extrapolated this to 10 yr at Wills Eye Hospital (Philadelphia, Pennsylvania), saying that there had been no vitreous loss in that time, with an average of 250 cases per year. The authors then remind us of the letter from Massachusetts Eye and Ear Infirmary in Boston, Massachusetts, where again, with a 10-yr history of using succinylcholine during open eye surgeries, they had no loss of vitreous. 3
In general, I agree with Vachon et al. 1that succinylcholine should be avoided in the induction of patients with open globes. However, at the Kresge Eye Institute in Detroit, Michigan, it is believed that there are situations in which succinylcholine should be used.
After institutional review board approval, I reviewed all open globe surgeries performed at my institution in a 24-month period. There were 59 cases. Of those, 1 was a planned fiberoptic intubation because of facial injuries; 8 received succinylcholine; and 5 were difficult intubations, requiring more than one attempt. In all 59 cases, comparing ophthalmologists’ comments in the preoperative assessment and after induction, similar to the process used by Libonati et al. , 2there were no increases in vitreous loss, no lens or uvea extrusion, and no excessive intraocular bleeding causing further extrusion.
I propose that two questions should be asked before the decision about the use or the avoidance of succinylcholine in open globe surgeries:
Is this an easy airway? In that setting, regardless of the patient’s aspiration risk and regardless of the viability of the eye, I believe that succinylcholine can be avoided and replaced with the currently available short- or intermediate-acting nondepolarizing muscle relaxants.
If the airway assessment, using whatever tools the anesthesiologist prefers, shows that this could be a difficult intubation, regardless of the patient’s aspiration risk, a second question becomes important:Is the eye viable? In that setting, the anesthetic induction plan may need to be changed.
If, during the preoperative ophthalmologic examination, it is believed that the eye is not salvageable and if the surgery is to assess the damage and create a cosmetic closure, I prefer to use fiberoptic laryngoscopy. This, I realize, may increase intraocular pressure (gagging from local anesthetic spray, retching from local anesthetic nebulized breathing treatments, bucking from transtracheal injection, hypercarbia from sedation, and other problems), but this increase should be similar to that from blinking, crying, or rubbing the eye.
If the ophthalmologist believes that the eye is viable, I prefer using succinylcholine over any other modality. In this setting, the nondepolarizing drugs may have a prolonged effect, with increases in intraocular pressure from mask application, hypercapnia with multiple attempts, and a longer time with an unprotected airway. Awake fiberoptic laryngoscopy may cause the intraocular pressure problems mentioned above and is best avoided if the eye is viable. In this setting, when a decision is made that succinylcholine is the safest choice, I start with other drugs that attenuate the intraocular pressure effect of succinylcholine, such as thiopental, 4propofol, 5narcotics, 6,7nifedipine, 8or lidocaine. 9
In summary, this algorithm involves two questions: Is this an easy airway? Is the eye viable? It results in three decision limbs: If the airway is easy, the recommendation is to avoid succinylcholine. If the airway is difficult and the eye is not viable, the recommendation is fiberoptic laryngoscopy. If the airway is difficult and the eye is viable, the recommendation is to use succinylcholine. With this algorithm, as mentioned in the review, 8 patients (out of 59) received succhinylcholine over a 2 year period, and none of the 59 patients had adverse outcomes.
In closing, I would like to compliment Vachon et al. on their review and on giving the issue a historical perspective. However, although I agree that primum non nocere is a good dictum, I am afraid that the fact that the Mayo Clinic avoids succinylcholine in open eye injuries may go against the process used at Wills Eye Hospital and Massachusetts Eye and Ear Infirmary. Granted, there are newer, shorter-acting nondepolarizing muscle relaxants that were not available to Libonati et al. 2or to Donlon 3in the mid-1980s, but those drugs have yet to replace the fast-onset and short-duration profile of succinylchioline. 10Therefore, I believe that some situations may present themselves in which it is more harmful to avoid succinylcholine.