Oculocardiac reflex in sedated patients having laser in situ keratomileusis

The Oculocardiac Reflex: A Review

BACKGROUND

A typical oculocardiac reflex (OCR) is a moderate trigemino-vagal bradycardia elicited by tension on an extraocular muscle (EOM) during strabismus surgery; however, many other orbital stimuli can elicit cardiac slowing including retinopathy of prematurity examination.

METHODS

World literature related to trigeminovagal and oculocardiac reflex covering over 15,000 patients including 51 randomized clinical trials and case reports are analyzed and reviewed. Under an ongoing observational trial in Alaska, anesthetic, patient and surgical influences on routine strabismus surgery using prospective, uniform EOM tension are compared seeking sufficient sample size to characterize this individually widely variable cardiac response.

RESULTS

With adequate sample size, and emphasizing clinical studies controlling type of EOM, muscle tension amount and duration, anticholinergic and opioid medications, the following augment OCR; rapid-acting opioids and dexmedetomidine while OCR is reduced in older patients, the right eye, less EOM tension, deeper inhaled agents, hypocarbia, anticholinergic medications and orbital block. In re-operations, the former are relatively poor predictors of subsequent OCR.

CONCLUSION

Profound bradycardia can occur in almost 10% of strabismus surgery cases without anticholinergic preventive measures, but reliable prediction of OCR remains elusive. With foreknowledge and careful anesthetic monitoring of the patient before EOM manipulation, residual adverse sequelae from OCR are fortunately very rare. Despite well over a century of experience, the teleology for this occasionally dramatic cardiac response to eye surgery is still not known.

Suction stability management in small incision lenticule extraction: incidence and outcomes of suction loss in 4000 consecutive procedures

PURPOSE

To report the incidence and outcomes of suction loss during small incision lenticule extraction (SMILE).

METHODS

The incidence of suction loss was measured over 4000 consecutive SMILE procedures and categorized by cause, the interface in which suction was lost and management (restart/continue SMILE, re-SMILE thinner cap, convert to laser in-situ keratomileusis [LASIK]). One-year outcomes were compared to the fellow eye where no suction loss occurred.

RESULTS

There were 20 cases of suction loss (0.50%): during the lenticule interface in seven eyes, lenticule side cut in one eye, cap interface in nine eyes and small incision for three eyes. Small incision lenticule extraction (SMILE) was continued in seven eyes, thinner cap SMILE in four eyes, LASIK in eight eyes, and the small incision was manually completed in one eye. Suction loss was caused by a Bell's reflex in 10 eyes, fixation light tracking in six eyes, patient anxiety in two eyes, a nociceptive reflex in one eye and false suction in one eye. There was no difference in results for suction loss and fellow eyes, respectively: uncorrected distance visual acuity was 20/20 or better in 100% in both groups, spherical equivalent was within ±0.50 D in 85% and 79%, one line loss of corrected distance visual acuity in 5% and 0%, and no eyes lost two lines.

CONCLUSION

Suction loss can be managed depending on the interface during which suction is lost. Treatment was completed on the same day in all instances. Visual and refractive outcomes were unaffected compared to the fellow eye in this series.

Downbeat nystagmus induced by sedation in LASIK

Nystagmus was elicited during lasik under sedation in two patients that were treated for depression. Nystagmus was not present before or after surgery. Nystagmus can be pharmacologically induced and can be a hazard to refractive surgery.

Strabismus surgery under augmented topical anesthesia

PURPOSE

Recently, topical lidocaine 2% jelly had been used in phacoemulsification and trabeculectomy surgeries. The purpose of this study is to evaluate the efficacy and stability of one-stage adjustable suture using topical lidocaine jelly 2% in combination with intravenous nalbuphine (Nubain).

METHODS

Forty adult patients aged 16 to 46 years (median, 24 years) underwent adjustable rectus muscle surgery under topical lidocaine jelly 2% and intravenous 10 mg nalbuphine given 10 minutes before surgery. Adjustment was performed on the operating table before conjunctival closure. The stability of adjustment was studied by comparing the postadjustment deviation to that at 1 day, 1 week, and 3 weeks postoperatively. Success was defined as alignment within 10 prism diopters on distant fixation. Analgesia was assessed using Verbal Description Scale. Changes in vital signs were recorded during surgery to evaluate the oculocardiac reflex.

RESULTS

Forty rectus muscles were recessed, 22 muscles were resected, 3 muscles were tucked, and 2 muscles were retrieved. During the operation, 35 patients expressed no pain, 3 patients complained of discomfort, and 2 patients complained of distressing pain and required an additional 10 mg of intravenous nalbuphine. Thirty-eight patients (95%) were successfully aligned during the first postoperative day, 37 patients (92.5%) after 1 week, and 36 patients (90%) after 3 weeks. Intraoperative cardiac monitoring did not record positive oculocardiac reflex in any patient.

CONCLUSION

Lidocaine jelly in combination with intravenous nalbuphine is an effective topical anesthesia strategy that provides for the patient's comfort and the surgeon's ability to fine-tune ocular alignment on the operating table.

Oculocardiac reflex in a nonsedated laser in situ keratomileusis patient

A healthy 21-year-old man had laser in situ keratomileusis (LASIK) in the right eye for a refractive error of -7.0 diopters. The electrocardiogram findings and heart rate were recorded before LASIK; during eye lid speculum insertion, vacuum application, corneal flap preparation, and excimer laser keratectomy; and after the procedure. The pre-LASIK heart rate was 90 pulses/min. Severe bradycardia of 40 beats/min developed during vacuum application, and the procedure was terminated. Severe bradycardia caused by an oculocardiac reflex may occur during LASIK, and patients should be closely monitored during the procedure.

Electrocardiographic changes during subconjunctival injections

Electrocardiographic changes were investigated in 53 patients during subconjunctival drug injections. Decrease in heart-rate of more than 10% or arrhythmia was observed in 25 (47.2%) of the patients, who were considered to have a positive oculocardiac reflex. In the control group of 35 patients, only 3 (8.6%) were found to have a significant decrease in heart rate during blood sampling from antecubital vein (p = 0.000). Young age was a significant risk factor for oculocardiac reflex during injections (p = 0.01). Patient gender, verbal pain score, satiety, experience of periocular injections, injected drug type were not found to be risk factors. All patients with oculocardiac reflex were asymptomatic; however, it is still wise to have emergency supplies ready for any circulatory derangement during subconjunctival injections.