Regional anaesthesia for surgical repair in selected open globe injuries in adults

Abstract

Purpose

To determine whether the combination of topical, intracameral and facial nerve blocks would produce adequate analgesia for repair of open globe injuries without increasing intraocular tension.

Methods

A comparison of combined O’Brien’s block (facial nerve block), topical ropivacaine and intracameral lignocaine versus peribulbar block in 100 randomly selected cases of traumatic corneal rupture. Patients were randomly divided in two groups of 50 each based on those receiving the combined approach (Group T) and those undergoing peribulbar block (Group P). Patients were excluded if there was rupture with significant scleral extension, the interval between trauma and presentation greater than 2 h, presence of hypopyon, rupture with significant corneal oedema, expulsion of intraocular contents with a collapsed globe and monocular cases.

The effect of the anaesthetic was compared by patient comfort and surgeon comfort, the incidence of vitreous prolapse and the requirement of incremental sedation. The Student’s “t” test, the “Z” test, and Chi Square tests were used where appropriate. P < 0.05 was considered statistically significant.

Results

The average patient comfort in Group P was 5.67% greater than Group T (P > 0.05). The average surgeon comfort and patient comfort between groups were similar (P > 0.05, both comparisons). Incremental sedation was required in 16% of patients in Group T compared to 8% in Group P (P = 0.218363). The total sedation dosage required for each group was similar. The incidence of vitreous prolapse was statistically significantly higher by 14% in Group P compared to Group T (P = 0.03731).

Conclusions

Our combined technique proved as efficacious as peribulbar block in providing adequate local anaesthesia and reducing the incidence of vitreous prolapse. We recommend greater use of this technique for repair of open globe injuries especially in locations where full time anaesthesia services are not available.

Introduction

Open globe injury (OGI) is an ocular emergency and surgical repair should be performed as early as possible in order to restore the structural and functional integrity of the eye. Although regional orbital anaesthesia such as retrobulbar or peribulbar blocks are most commonly used for ocular surgeries, they are relatively contraindicated in OGI because any retro/peri-orbital infiltration of local anaesthetic exerts pressure on the open globe, risking prolapse of the ocular contents. To avoid the risk of prolapse, general endotracheal anaesthesia (GETA) is commonly employed in cases of OGI.^1–3 However GETA also poses some challenges. Firstly, most eye hospitals (particularly in developing countries) do not have twenty-four hours anaesthesia services. Secondly, patients with a full stomach can regurgitate and aspirate gastric contents.

To address these problems corneal ruptures that are less severe are often repaired under regional anaesthesia and intravenous sedation,⁴ with peribulbar block^4,5 being the most common technique. However, peribulbar block transiently increases intraocular pressure (IOP)⁶ which may increase complications in a comprised globe. To eliminate the risk of increased IOP completely, we have devised a technique of regional anaesthesia for adult sclero-corneal rupture repair surgery that will not increase IOP yet still provide adequate patient comfort. The technique consists of topical instillation of 0.75% ropivacaine combined with facial nerve block with O’Brien’s approach with 2% lignocaine with adrenaline and intracameral injection of 1% lignocaine (preservative free) along with intravenous sedation.

Materials and methods

After submitting the study design and obtaining approval from Institutional Review Board the study was conducted at a tertiary eye hospital between 1st August 2010 and 31st March 2011. One hundred consecutive patients with traumatic corneal rupture presented to the institutional Emergency Room (ER) between 01/08/2010 to 31/03/2011 were recruited for the study. A thorough history was taken with special reference to time and the nature of trauma. Subsequently a complete ocular examination was performed including slit lamp examination to document the following:

• 1.Presenting vision.
• 2.Extent of the corneal rupture in millimeters.
• 3.Edge of the rupture with special importance to adjacent corneal oedema and infiltrate.
• 4.Status of intraocular contents such as uvea (hypopyon, hyphaema), status of the lens (dislocated, subluxated or cataractous).
• 5.Status of adnexa including any associated lid injury, subconjunctival haemorrhage or oedema, conjunctival tears, etc.

Selection criteria: Patients were selected according to the following criteria:

• 1.Age: 18–40 years.
• 2.Sex: Both sexes.
• 3.No associated systemic illness. ASA grade-I–II.
• 4.No history of allergy to the drugs used in the study.
• 5.No psychological problem/claustrophobia/mental retardation.
• 6.Airway: No apparent airway difficulty; Mallampatti grade: 1–2.
• 7.Ophthalmic assessment: Only patients with sclero-corneal ruptures of lesser severity, without significant corneal loss or uveal prolapse were selected. A senior ophthalmologist screened the probable candidates and selected the suitable subjects for enrolment in the study.

Exclusion criteria: Patients were excluded based on the following criteria:

• 1.Rupture with significant scleral extension.
• 2.Interval between the time of trauma and the time of presentation more than two hours.
• 3.Rupture associated with hypopyon.
• 4.Rupture with significant corneal oedema (corneal oedema extending more than 2 mm from the edge).
• 5.Extensive corneal rupture with auto expulsion of intraocular contents with collapsed globe.
• 6.One eyed patient.

The patients were informed about the nature of the study and informed consent was obtained. The patients were randomly divided into two groups of 50 each based on:

• 1.Group P: To receive peribulbar block along with intravenous sedation.
• 2.Group T: To receive the topical–intracameral–facial nerve block combination along with intravenous sedation.

Randomization: A register was maintained for all patients and each patient was assigned a serial number. Patients were assigned to either of the two groups with the help of a computer generated random number table (MS Excel).

Anaesthesia protocol: All patients were premedicated with Syr. Midazolam (0.5 mgkg⁻¹). In the operating room prior to surgery, an intravenous (i.v) access was secured with an 18 G i.v cannula. Patients in Group P underwent a peribulbar block with a combination of equal volumes of 2% lignocaine with adrenaline and 0.5% bupivacaine. Patients in Group “T” received unpreserved topical ropivacaine 0.75%, and an injection of ondansetron 4 mg and an injection of glycopyrrolate 0.2 mg intravenously. Subsequently, an injection of midazolam 0.04 mgkg⁻¹ intravenously, and an injection of intravenous fentanyl 0.5 mcgkg⁻¹ were slowly administered. Oxygen at the rate of 2–3 l/min was administered via nasal cannula. The patient’s neck was extended, to keep the airway open under sedation. If required, a 4 inch foam pillow was placed under the shoulder to facilitate neck extension. Guedel’s airway was kept ready for use in case of any upper airway obstruction. Patients in Group T received a facial nerve block using O’Brien’s approach. The corneal reflex was checked by a sterile cotton wisp after which the surgery commenced. Patients in Group T received an intracameral injection of 1% lignocaine if any iris or uveal manipulation was required during surgery. Incremental sedation of intravenous 1 mg midazolam was administered as necessary. The pulse rate, blood pressure, peripheral oxygen saturation (SpO2) and ECG were monitored during surgery.

The requirement for incremental sedation and any incidence of vitreous prolapse intraoperatively were noted.

As there is no standardized scoring system, we prepared a subjective scoring system. Postoperatively, the operating surgeon was asked to rate the anaesthesia on a scale of 1–5, 1 being the worst and 5 being the best possible condition to operate. A score of 1–2 was considered poor anaesthesia, 3-fair, 4-good and 5-excellent anaesthesia. The patients were asked to rate their experience on a scale of 1–5. A score of 1–2 was considered bad anaesthesia, 3-fair, 4-good, and 5-excellent.

Statistical analysis was performed. The age distribution of the study population, duration of surgery, the surgeon’s grading of comfort, the patients’ grading of comfort and total sedation dosage were analysed with Student’s “t” test; the sex distribution by the “Z” test, and the requirement of incremental sedation and incidence of vitreous prolapse by the Chi Square test. All statistical calculations were performed with Microsoft Excel (Microsoft Corp., Redmond, WA, USA). P values for “Z” test and Chi Square tests were calculated with an online web based calculator. P < 0.05 was considered statistically significant.

Results

Age and sex distribution were similar between groups. The average duration of surgery was 7.42% longer in Group P (51.71 min) compared to Group T (47.87 min). This difference was not statistically significant (P = 0.06275). The average patient comfort level in Group P was 5.67% greater than Group T. This difference was not statistically significant (P > 0.05). The average surgeon comfort between groups was similar (P > 0.05). Incremental sedation was required in 16% of patients in Group T compared to 8% in Group P. There was no statistical difference in incremental sedation between groups (P = 0.218363). The total sedation dosage required for each group was similar. The incidence of vitreous prolapse was statistically significantly higher by 14% in Group P compared to Group T (P = 0.03731) (Fig. 1). There were no anaesthetic related complications in any of the patients. Complete akinesia of the eyeball was achieved in most of the patients receiving peribulbar block (86%) while some movement persisted in all of the patients receiving the topical–intracameral anaesthesia.

Figure 1.

Incidence of vitreous prolapse intraoperatively in patients with corneal rupture. Group P denotes patients who underwent anaesthesia with a peribulbar block. Group T denotes patients who underwent topical and intracameral anaesthesia with a facial nerve block.

Discussion

Topical anaesthesia has recently become popular in the ophthalmic surgery. It has been successfully employed for phacoemulsification during cataract surgery. Unpreserved 4% lignocaine, unpreserved 1% ropivacaine, 0.5% tetracaine and 0.4% oxybuprocaine hydrochloride have been used topically for cataract surgery.^7–9 Topical anaesthesia has also been successfully used for penetrating keratoplasty.¹⁰ Riddle et al.¹⁰ found that patients experienced mild discomfort when a penetrating keratoplasty was performed under topical anaesthesia only. It was further noted that discomfort arose when the lens was manipulated causing pain in the cilliary body and iris root areas.¹⁰ The combination of topical anaesthesia and intracameral injection of 1% lignocaine has been reported to produce acceptable levels of patient comfort.^8,9,11 When intracameral injection was used in addition to topical anaesthesia, mean satisfaction levels of patients were found to be higher than retrobulbar anaesthesia.⁸ We found topical–intracameral anaesthesia to be adequate for the surgical repair of OGI, which concurs with the findings of Scott et al.^13,14 and Boscia et al.¹⁵

An O’Brien’s facial nerve block was added to avoid squeezing of the eyelids which may increase intraocular tension and damage an already compromised eye.

O’Brien block – brief description: (Fig. 2)

Figure 2.

Techniques of facial nerve block.

The O’Brien block is used to block the facial nerve at the proximal trunk. The condyloid process of the mandible is palpated just in front of the tragus of the ear by asking the patient to open and close his or her mouth. The process is felt to slip forward under the finger during this movement. At the site of injection, the skin is partially anaesthetized by raising an intradermal wheal with the local anaesthetic. A 5 ml syringe with a 24 G needle 1 inch in length is used. The needle should pass straight down to the periosteum; 2–3 ml local anaesthetic solution is injected, and after withdrawing the needle, firm pressure and local massage are applied. Paralysis of the orbicularis usually occurs within 7 min.

We chose O’Brien technique because it is easy to administer, produces reliable effect and causes minimal local oedema or haemorrhage compared to the other techniques of facial block.¹² In our study the average patient comfort as well as surgeon comfort levels were satisfactory in both Groups. Alternately, Scott et al.^13,14 used peribulbar block and the patients were comfortable, Boscia et al.¹⁵ used only topical anaesthesia for repairing OGI and all of the patients complained of mild to moderate pain and the operating surgeons complained of discomfort. In our study incorporation of an intracameral injection of lignocaine eliminated pain arising from uveal tissue manipulation, providing a greater patient comfort. Additionally by preventing eyelid squeezing, (by application of facial nerve block) surgeons comfort increased. While akinesia was achieved in most of the patients receiving peribulbar block, some ocular movement persisted in all patients receiving the topical–intracameral anaesthesia.

Peribulbar blocks have many disadvantages including the risk of globe perforation and haemorrhage. Peribulbar block can cause transient rise in IOP.⁶ Although a transient increase in IOP (lasting one minute) maybe insignificant in an intact globe, it may increase complications in an open globe. For example, we found a higher percentage of vitreous prolapse in Group P (20%) compared to Group T (6%). Since our technique does not involve any injection of lignocaine into the orbit, the risk of an IOP spike is negated.

No anaesthetic related complications of i.v sedation occurred in the duration of the study.

Thus our technique not only provided safe and adequate anaesthesia for the repair of OGI, but also reduced the need for administration of GETA. In eye hospitals, where twenty-four hours anaesthesiologist support is not available, adoption of this method may reduce the waiting time for patients with OGI, leading to earlier intervention and better visual outcomes. Therefore we recommend that this method should be widely adopted in areas where anaesthesiology services are not always available or scarce.

Conclusion

The combination of topical and intracameral anaesthesia with a facial nerve block provides acceptable surgical conditions for the repair of limited anterior globe injuries.