A surgically placed epidural catheter in a patient with spinal trauma.

PURPOSE: To report the successful perioperative anaesthetic and analgesic management of a spinal trauma patient with a surgically placed epidural catheter. CLINICAL FEATURES: A 15-yr-old adolescent woman sustained an unstable spinal column injury with an incomplete neurological deficit following a high speed motor vehicle accident. She was scheduled for spinal decompression and stabilisation through a left thoracoabdominal approach. Balanced general anaesthesia was undertaken. Prior to closure, a multi-orifice epidural catheter was surgically placed under direct vision 5 cm into the anterior epidural space. The catheter was then tunnelled out through the psoas muscle and secured in place. Combined epidural-general anaesthesia was then initiated for the duration of the case using 5 ml bupivacaine 0.25% after an initial test dose of 3 ml lidocaine 1.5% with epinephrine. An infusion of bupivacaine 0.10% and fentanyl 5 micrograms.ml-1 at 8 ml.hr-1 using patient controlled epidural analgesia (PCEA) provided excellent postoperative pain control for four days. She had an uncomplicated postoperative course. CONCLUSION: A surgically placed epidural catheter provided excellent, safe, perioperative anaesthesia and analgesia in this patient with unstable spinal trauma.

Laryngeal mask airway with mouth opening less than 20 mm.

We describe the use of a laryngeal mask airway in three adult patients whose mouth opening varied from 12 mm to 18 mm. The first patient's incisal opening was 12 mm. His airway was otherwise normal and the standard laryngeal mask was used as the definitive airway for the 90 min revision of facial scars and bone graft to mandible. The second patient, who had an incisal opening of 18 mm, was scheduled for posterior fossa craniotomy. She adamantly refused awake fibreoptic tracheal intubation. Following induction of general anaesthesia, a standard laryngeal mask was inserted and, through this, fibreoptic intubation was performed. The third patient, in addition to a mouth opening of only 18 mm, had limited neck movement from previous flap reconstruction following mandibulectomy, hemiglossectomy and radical neck dissection. For three more reconstructive head and neck procedures that ranged from 90 min to nine hours, the flexible reinforced laryngeal mask was inserted under topical anaesthesia and its correct position confirmed by fibreoptic laryngoscopy before induction of general anaesthesia. Maintenance of anaesthesia in all cases was uneventful and there were no postoperative complications.

The electroretinogram during orbital compression following intraorbital regional block for cataract surgery.

The electroretinogram (ERG) is a transient biopotential that reflects the electrical response of the distal retina to photostimulation. Disturbances in retinal circulation produce characteristic abnormalities in the ERG wave form. The objective of this study was to investigate the changes in the ERG produced by combined retrobulbar and peribulbar injections of a large volume (8 ml) of local anaesthetic, followed by ocular compression. Electroretinogram recordings were obtained from skin electrodes placed on the infero orbital ridge in response to stroboscopic flash stimulation in 34 adult patients undergoing cataract surgery: (a) prior to regional anaesthesia (baseline condition); (b) within one minute after regional anaesthesia of the orbit (block condition); (c) after ten minutes of orbital compression with a Honan's device at 30 mmHg. (compression condition); (d) and five minutes after removal of orbital compression (recovery condition). The ERG implicit times of both a- and b-wave increased (P < 0.001) after anaesthetic block. The amplitude of the a- and b-waves also decreased (P < 0.001) immediately following anaesthetic block and continued to decrease following application of the compression device (P < 0.01). Following removal of ocular compression the amplitude of the b-wave increased (P < 0.01). Only the a-wave implicit time (P < 0.005) decreased with release of ocular compression. These findings are compatible with the ERG changes of transient retinal ischaemia produced by ocular compression.

Periocular local anesthesia: medial orbital as an alternative to superior nasal injection.

We developed a new technique, the medial orbital pericone local anesthetic block, that surgeons can use a secondary block when inferotemporal retrobulbar or peribulbar/periocular injection of local anesthetics results in incomplete anesthesia. Unlike secondary local injections placed in the superonasal quadrant of the orbit, our technique injects the anesthetic into the fat compartment of the nasal side of the globe, a site that is relatively avascular and lacks vital anatomic structures. In more than 15,000 patients, this method proved an effective, safe means of secondary block and promoted orbicularis oculi muscle akinesia.

Effect of combined peribulbar and retrobulbar injection of large volumes of anesthetic agents on the intraocular pressure.

A prospective randomized study was done in 79 patients undergoing elective routine cataract surgery in which the Kelman phacoemulsification technique was used with placement of an intraocular lens. In all the patients anesthesia was induced with both a peribulbar and a retrobulbar injection of a large volume (total 10.5 mL) of local anesthetic. The patients were randomly assigned to receive either the peribulbar (39 patients) (group 1) or the retrobulbar (40 patients) (group 2) injection first. The intraocular pressure (IOP) was measured five times during anesthesia. The mean elevation in IOP immediately after the first injection was 0.4 mm Hg in group 1, compared with 2.0 mm Hg in group 2. Twenty minutes after both injections had been given and a Super Pinky pressure device had been placed on the eye, the mean decrease in IOP from the preoperative value was 3.1 mm Hg in group 1 and 4.8 mm Hg in group 2. We conclude that a combined peribulbar and retrobulbar approach is a safe and effective alternative method of regional anesthesia for cataract surgery.

Comparison of plain with pH-adjusted bupivacaine with hyaluronidase for peribulbar block.

Fifty patients scheduled for cataract surgery under peribulbar block were randomised to receive either plain (pH 5.4) or pH-adjusted (pH 6.8 range 6.7-6.9) 0.75% bupivacaine. Hyaluronidase was added to both solutions prior to peribulbar block. The time of onset of akinesia of the globe and the need for supplementary injections were recorded by an independent observer. Patients who returned for surgery to the second eye received the alternative local anaesthetic solution for the second peribulbar block. The relative efficacy of the different anaesthetic solutions was compared in patients who underwent unilateral surgery (Group A, n = 50). In 12 patients (Group B) who underwent bilateral surgery, direct comparisons between eyes in the same patient were possible. In both groups of patients, eyes receiving peribulbar block with the pH-adjusted solution showed a shorter time to partial akinesia of the globe (P less than 0.05). However, there was no difference between the solutions in the time to complete akinesia of the globe, but the number of supplementary injections required for an effective block with the pH-adjusted solution was increased. Onset time to akinesia of the lateral and superior rectus muscles was shortened in patients receiving the pH-adjusted solution but there were minimal effects on the medial and inferior recti.

Transforaminal escape of a lumbar epidural catheter.

A patient is presented whose lumbar epidural catheter was found to lie in the paravertebral tissues during a right radical nephrectomy. The catheter had been placed with the patient awake and the procedure performed in a routine fashion without difficulty or indication of catheter malposition. Four ml of 2% CO2 lidocaine were initially injected as a test dose without any demonstrable effect. After the induction of general anaesthesia, fentanyl 100 mu and 0.25% bupivacaine 10 ml were injected slowly into the catheter. Previous studies suggest that transforaminal escape of an epidural catheter occurs after 1-6% of insertions. It may occur without nerve root symptoms during catheter placement. The authors recommend that epidural catheters be introduced whilst the patients are awake and an effective block demonstrated before induction of general anaesthesia.

The laryngeal mask airway: clinical appraisal in 250 patients.

The laryngeal mask airway consists of a tubular oropharyngeal airway to the distal end of which is sealed a silicone laryngeal mask with an inflatable rim which provides an airtight seal around the larynx. It provided a clear airway in 238 of 250 elective and emergency non-obstetrical patients for a wide variety of surgical procedures, ranging from minor gynaecological and urological procedures to major abdominal and orthopaedic surgery with either spontaneous respiration or intermittent positive pressure ventilation. Anaesthetic techniques and drugs were similar to those which would have been used for the same procedures if face-mask or tracheal intubation had been employed. Blind insertion of the laryngeal mask airway was successful at the first attempt in 187 patients, some manipulation was required in 61 patients, and insertion was impossible in two patients, each of whom had a small mouth. In ten patients tracheal intubation was required because of airway obstruction or a large gas leak. The LM airway does not require laryngoscopy for its insertion, it relieves the anaesthetist's hands from holding a face-mask, it cannot be misplaced in the oesophagus, and it is well tolerated during emergence from anaesthesia.