Regional anaesthesia for intraocular surgery

The role of anaesthetists in providing local anaesthesia for intraocular surgery has changed over the past decade. No longer confined to the interested few, more and more anaesthetists are involved in monitored care and/or are performing eye block anaesthesia. This reiew summarizes the information related to eye block anaesthesia. The salient features of the orbital anatomy important for safe conduct of eye block anaesthesia are described. The techniques for retrobulbar and peribulbar anaesthesia, including facial nerve blocks, anaesthetic mixture, types of needles, and softening the eye are presented. Complications such as retrobulbar haemorrhage, globe penetration / perforation, visual impairment, brainstem anaesthesia, muscle injury, and oculocardiac reflex are explored. The implications of anticoagulant therapy are examined. The choice between retrobulbar and peribulbar blocks and the role of anaesthetists are discussed.     

Regional anaesthesia for intraocular surgery

The first recorded use of local anaesthesia for surgery wasthe instillation of cocaine into the conjunctival sac in 1884by an Austrian ophthalmologist, Karl Koller (1858–1944),at the suggestion of Sigmund Freud. In the UK, during the past10 yr, a major change in anaesthetic practice has taken placeand the majority of ophthalmic surgical patients now undergoregional rather than general anaesthesia. This change has beendriven in part by the pressure to undertake surgical proceduresas day cases. It is important to remember, however, that thereare specific risks associated with local anaesthesia for intraocularsurgery and that serious complications of general anaesthesiahave always been uncommon in ophthalmology, despite the advancedage and poor state of health of many patients in this group.     

Peribulbar anesthesia for primary vitreoretinal surgery.

We prospectively studied the efficacy of peribulbar anesthesia in 76 consecutive patients who underwent vitreoretinal surgery. The mean duration of anesthesia was 124.74 +/- 50.17 minutes, and the mean duration of akinesia, 151.5 +/- 54.45 minutes. Adequate anesthesia and akinesia, independent of the duration of surgery, was obtained in 26 of 33 (78.8%) patients who underwent vitrectomy; 9 of 32 (28.1%) who underwent scleral buckling; and 2 of 11 (18.2%) who underwent vitrectomy combined with scleral buckling. In all, topical and systemic supplementation of drugs for inadequate anesthesia or akinesia allowed 32 of the 33 (97%) vitrectomies, 30 of the 32 (94%) scleral buckling procedures, and all 11 of the combined surgeries to be completed as planned. Three (4%) patients vomited, moved, or were restless, resulting in an operative complication or postponement of surgery. Fifty-eight (76%) said they would desire similar anesthesia if subsequent surgery was needed in the same or fellow eye. We conclude that peribulbar anesthesia should be considered primarily for patients requiring vitreous surgery alone, and as an alternative for patients requiring scleral buckling or combined surgery for whom general anesthesia is contraindicated.     

Normocapnic anaesthesia with trichloroethylene for intraocular surgery

Measurements of intraocular pressure (IOP) by applanation tonometry in twelve patients undergoing lens extraction showed that a normocapnic anaesthetic technique using 0.4% trichloroethylene with controlled ventilation of the lungs (IPPV) with large tidal volumes (14 ml/kg) reduced IOP by 13--20%. There was only a small reduction in arterial pressure. Normocapnia was easy to achieve by use of the single-limb co-axial Penlon (Bain type) anaesthetic breathing circuit in conjunction with an electrically-driven, small and inexpensive lung ventilator. The anaesthetic technique described using trichloroethylene is suitable for lens extraction surgery when it is desired to avoid a halothane anaesthetic for any reason.     

Peribulbar anesthesia in retinal reattachment surgery.

We prospectively evaluated the effectiveness of peribulbar anesthesia in retinal reattachment surgery. Of the 24 patients studied, 2 required retrobulbar supplementation during the latter part of the surgery. Our results show that peribulbar anesthesia can be effectively used for retinal reattachment surgery and probably should be the preferred form of local anesthesia for this surgery, since the eyes involved have a relatively high incidence of axial myopia and posterior staphyloma.     

Peribulbar anaesthesia using a mixture of local anaesthetic and vecuronium

The aim of this double-blind, randomised study was to assess the effects of the addition of 0.5 mg of vecuronium bromide to a standard local anaesthetic mixture used for peribulbar anaesthesia. We studied 60 patients undergoing regional anaesthesia for intra-ocular surgery and were primarily interested in the quality of globe and lid akinesia. All received a mixture of 5 ml 2% lignocaine with 1:200 000 adrenaline, 5 ml 0.75% bupivacaine and 150 IU hyaluronidase with either 0.9% saline 0.25 ml (group A, n  = 30) or vecuronium bromide 0.25 ml (0.5 mg) (group B, n  = 30). Eye movements assessed at both 5 and 10 min were significantly reduced in the vecuronium group (group B) (p < 0.05). We conclude that the addition of vecuronium at a dose of 0.5 mg to the standard local anaesthetic mixture improves the quality of globe and lid akinesia.     

Total intravenous anaesthesia versus inhalational anaesthesia for dental day surgery.

Fifty young healthy and unpremedicated patients scheduled for removal of impacted teeth were randomly allocated to receive either total intravenous anaesthesia with propofol or conventional thiopentone/isoflurane/nitrous oxide anaesthesia. A double-blind postoperative assessment showed the former group to have a shorter reversal time and faster recovery of faculties, i.e. speech, memory as well as ability to sit up and walk without assistance (P < 0.01). There was no incidence of hypotension and of awareness in either group. The incidence of headache, nausea and vomiting was higher in the thiopentone/isoflurane/nitrous oxide group.     

Epidural anaesthesia for day care surgery.

The records of 682 patients who received epidural anaesthesia for day care surgery were reviewed. The advantages and disadvantages of this form of anaesthesia is discussed. No major complications were recorded.     

Spinal anaesthesia for day case surgery.

Postoperative morbidity in fifty day care patients undergoing spinal anaesthesia was evaluated by means of a postoperative questionnaire. Despite the use of a 26G spinal needle in all patients, there was an overall incidence of spinal headache of 18%, which rose to 39% when considering patients under 40 years of age. Several spinal headaches of three to five days' duration were reported. Patients receiving spinal anaesthesia were compared with a smaller group of patients receiving general anaesthesia for similar procedures, and this group showed no evidence of post-operative morbidity after 48 h. In agreement with a previous study, it is concluded that spinal anaesthesia is not a suitable technique for the young day care patient.     

Peribulbar anaesthesia: a double-blind comparison of three local anaesthetic solutions

A prospective, randomised, double-blinded study comparing three agents for peribulbar anaesthesia is reported. Sixty patients undergoing extracapsular cataract extraction under local anaesthesia were randomly allocated to receive peribulbar anaesthesia with lignocaine 2% with adrenaline; prilocaine 3% with felypressin 0.03 IU.ml-1 or 2% lignocaine and 0.5% bupivacaine in a ratio of 1:1, using a standardised two-injection technique. The pain of injection, time of onset of the block and the operating conditions at the start and finish of surgery were assessed. Peribulbar anaesthesia using lignocaine 2% was significantly more painful than the other solutions. The onset of anaesthesia adequate for surgery was similar in all three groups. Prilocaine 3% with felypressin was associated with the greatest number of blocks providing total akinesia of the eye. Inadequate duration of anaesthesia was seen in only one case; the solution used for this block was 2% lignocaine.