Visual experiences during cataract surgery: what anaesthesia providers should know

Recently published literature shows that most patients experience a variety of visual sensations during cataract surgery under local anaesthesia. Most patients (80-100%) retain at least some light perception in the operated eye and many also experience a variety of other visual sensations during cataract surgery under regional ophthalmic anaesthesia (retrobulbar, peribulbar and sub-Tenon's blocks) or topical anaesthesia. The visual sensations experienced include perception of movements, flashes, colours, changes in brightness, or the sight of surgical instruments, the surgeon's hands or fingers, or even the surgeon. These findings are clinically significant because 3-16.2% of patients who had cataract surgery under either regional or topical anaesthesia were frightened by their intraoperative visual experience. Fear and anxiety may cause some patients to become uncooperative during the surgery and may also induce a sympathetic stress response that might cause hypertension, tachycardia with myocardial ischaemia, hyperventilation or an acute panic attack. These effects are especially undesirable as the majority of cataract patients are elderly and have concurrent medical problems. Besides increasing the risk of intraoperative complications, a frightening visual experience may decrease patient satisfaction. Appropriate preoperative counselling has been shown to be effective in reducing the patients' fear. As most patients retain some visual function during cataract surgery under local anaesthesia, anaesthesia providers should be mindful of this phenomenon and offer appropriate preoperative information and counselling to their patients.     

Fasting regimens for regional ophthalmic anaesthesia

Members of the British Ophthalmic Anaesthesia Society were surveyed using a postal questionnaire. The response rate was 72.3%. Respondents were asked about starvation before regional anaesthesia for cataract surgery, the use of sedation in these patients, monitoring and if oxygen supplementation was given. The results show that most patients are not starved before this type of regional anaesthesia, and that the majority of patients receive no supplementary sedation or intravenous analgesia. Over 70% of patients received oxygen supplementation.     

Randomized double-blind clinical trial comparing topical and sub-Tenon's anaesthesia in routine cataract surgery

Background. Several local anaesthetic techniques are availablefor cataract surgery. Recently, topical anaesthesia has gainedin popularity. A randomized trial was designed to compare patientdiscomfort and intraoperative complications following routinecataract surgery under topical or sub-Tenon's anaesthesia. Methods. A randomized double-blinded placebo-controlled clinicaltrial of 210 patients assigned to either a sub-Tenon's group(sub-Tenon's anaesthesia with placebo topical balanced saltsolution, n=140) or a topical anaesthesia group (topical anaesthesiawith placebo sub-Tenon's injection of balanced salt solution,n=70) was carried out. All patients underwent phacoemulsificationwith intraocular lens implantation. Patients in the sub-Tenon'sgroup received a single injection (3 ml) of a combination oflidocaine 2% (2 ml) and bupivacaine 0.75% (1 ml), and four dosesof topical placebo (balanced salt solution). Patients in thetopical anaesthesia group received four doses of topical proxymethocaine0.5% and a placebo sub-Tenon's injection (3 ml) of balancedsalt solution. No intracameral injection of local anaestheticwas given. A 10-point visual analogue pain scale was used preoperativelyand for postoperative pain assessment immediately after theoperation and 30 min postoperatively. The intraoperative complicationsin the two groups were recorded. Results. The mean pain score immediately after surgery was 2.42(SD 2.2) in the sub-Tenon's group and 3.44 (2.3) in the topicalanaesthesia group (P=0.0043). The mean pain score 30 min aftersurgery was 1.24 (1.7) in the sub-Tenon's group and 2.25 (2.2)in the topical anaesthesia group (P=0.0009). Conclusions. Patients undergoing cataract surgery under topicalanaesthesia experience more postoperative discomfort than patientsreceiving sub-Tenon's anaesthesia. Surgery-related complicationswere similar in both groups.      

Anaesthesia in the United Nations Military Hospital, Dili, East Timor.

An analysis of the anaesthesia caseload of the United Nations Military Hospital and its predecessors over the first 12 months of operation from September 1999 has been performed. Most patients were East Timorese civilians or Australian Military personnel. General anaesthesia using the ULCO Portable Field Anaesthesia Machine was most commonly administered.     

Ambulatory cataract surgery: the patients' perceptions

There has been a slower uptake of ambulatory cataract surgery in the UK than the USA. We believe the primary aim of ambulatory cataract surgery is improved patient care. This prospective study assessed the perceptions and individual characteristics of patients undergoing ambulatory cataract surgery. This study demonstrates that 97.7% of patients undergoing ambulatory cataract surgery recommend this procedure as the treatment of choice. We conclude that ambulatory cataract surgery has many benefits, has a high level of patient satisfaction, and is suitable for the majority of patients.     

Anaesthesia-related diplopia after cataract surgery

Background. We studied the incidence and clinical characteristicsof persistent diplopia related to anaesthesia for cataract surgeryin a general hospital. Methods. This was a retrospective review of anaesthesia for3587 cataract surgeries. Of all the cases of diplopia referredto the ocular motility clinic after cataract surgery, thoseinvolving anaesthesia-related diplopia lasting longer than 1month were studied. Results. During the study period, 3450 cataract surgeries wereperformed by phacoemulsification and 137 by extracapsular extraction.Retrobulbar block was used in 2024 cases, peribulbar block in98, topical anaesthesia in 1420 and general anaesthesia in 43.Twenty-six cases of persistent diplopia were found (0.72% incidence),nine of which (0.25%) were considered to be related to anaestheticfactors; five of the latter involved the left eye. Five werecaused by paresis of the inferior rectus muscle and three byfibrosis. In one patient, the inferior oblique muscle was affected.Anaesthesia was by retrobulbar block in eight cases (0.39%)and by peribulbar block in one. No diplopia was found in patientswho had topical or general anaesthesia. Treatment was with surgeryin two patients and with prisms in six. One patient continuesto be studied. Conclusions. Persistent diplopia can occur after cataract surgeryusing retrobulbar block predominantly through direct damageto the inferior rectus muscle. The overall incidence of anaesthesia-relateddiplopia in this series was 0.25%. Br J Anaesth 2003; 90: 189–92     

Anaesthesia for magnetoencephalography in children with intractable seizures

BACKGROUND: Magnetoencephalography (MEG), a noninvasive technique for evaluation of epileptic patients, records magnetic fields during neuronal electrical activity within the brain. Anaesthesia experience for MEG has not yet been reported. METHODS: We retrospectively reviewed records of 48 paediatric patients undergoing MEG under anaesthesia. Thirty-one patients (nonprotocol group) were managed according to the anaesthesiologist's discretion. Premedication included oral midazolam, chloral hydrate or fentanyl oralet, intravenous midazolam or inhalational anaesthesia with sevoflurane. Anaesthesia was maintained with propofol, midazolam, fentanyl, alone or in combination. A subsequent protocol group (17 patients) received chloral hydrate as premedication and propofol for maintenance of anaesthesia. RESULTS: There was an overall 25% failure of interictal activity and localization on the MEG scan. In the nonprotocol group, 11 scans failed (35.5%). Of these, eight (72.7%) received midazolam orally. Only one failure (5.8%) was recorded in the protocol group in a patient who received chloral hydrate as sedation supplemented by sevoflurane. CONCLUSIONS: In our experience, midazolam premedication resulted in a high MEG failure rate (73%). Chloral hydrate premedication and propofol maintenance resulted in a lower incidence of MEG failure (5.8%). General anaesthesia with a continuous infusion of propofol or sevoflurane appears acceptable, although, lighter levels of anaesthesia might be required to avoid interference with interictal activity of the brain.     

Regional anaesthesia for ophthalmic surgery

Ophthalmic surgery can be conducted under local anaesthesia (LA), with techniques ranging from topical anaesthetic drops to sharp needle regional blocks. The sub-Tenon's block is the most common regional technique in current practice superseding sharp needle techniques (e.g. retrobulbar block). A sub-Tenon's block is a safe and effective means of providing analgesia, anaesthesia and good operating conditions.     

Plasma catecholamine response to cataract surgery: a comparison between general and local anaesthesia

We studied the plasma catecholamine, plasma glucose and cardiovascular responses to cataract surgery in 20 elderly patients allocated randomly to receive either general anaesthesia or local anaesthesia by retrobulbar block. Local anaesthesia prevented the increase in plasma noradrenaline, adrenaline and glucose concentrations found in those patients who received general anaesthesia and also improved cardiovascular stability. The results show the beneficial effects of local anaesthesia in preventing the hormonal, metabolic and cardiovascular changes found when cataract surgery is conducted under general anaesthesia.     

An investigation of factors affecting postoperative rewarming of adult patients

Aural canal temperature was measured for one hour after arrival in the recovery room in 200 adult patients who underwent one of the following types of major surgery: abdominal, pelvic, vascular, orthopaedic or prostatic. One group of 100 patients was studied in the recovery room of Hammersmith Hospital which was not equipped with a controlled system for constant ventilation and humidification, while the other 100 patients were studied in the recovery room of Edgware General Hospital, which had a constant ambient temperature and controlled relative humidity with 20 air changes/hour. The rate of rewarming was found to be similar in both groups. Within the range of ambient temperatures and relative humidities measured, patients over 60 years of age rewarmed more slowly than did patients under 60 years (p less than 0.05). General anaesthesia was associated with significantly faster rewarming than was local anaesthesia (p less than 0.01).     

Induction agents for day-case anaesthesia A double-blind comparison of propofol and midazolam antagonised by flumazenil

Early postoperative recovery was studied using sedation scoring, measurement of flicker fusion frequency and completion of Trieger test figures in 60 male patients who presented for vasectomy under general anaesthesia as day patients. Anaesthesia was induced in groups 1 and 2 (20 patients each) with mean (SD) doses of 0.16 (0.04) mg/kg or 0.16 (0.03) mg/kg midazolam respectively; group 2 received flumazenil 0.55 (0.19) mg after completion of surgery. The remaining 20 patients (group 3) received propofol 1.50 (0.24) mg/kg. Anaesthesia was maintained with isoflurane vaporized in 33% oxygen and nitrous oxide in all patients. Flumazenil tended to improve tests of recovery after midazolam anaesthesia, but early recovery after propofol anaesthesia was associated with better psychomotor test results and less impairment of mental state as judged by sedation and amnesia scoring.     

Metabolic control of non-insulin-dependent diabetic patients undergoing cataract surgery: comparison of local and general anaesthesia

We studied 40 elderly patients undergoing cataract surgery.Ten non-insulin-dependent diabetes mellitus (NIDDM) patientsreceived standardized general anaesthesia, 10 NIDDM patientsreceived local anaesthesia using retrobulbar block, 10 nondiabeticcontrol patients received general anaesthesia and 10 non-diabeticcontrols received retrobulbar block. We measured sequentialchanges in blood glucose, lactate and ß-hydroxybutyrate,serum cortisol and insulin, and plasma non-esterified fattyacid concentrations until 4 h after operation. The results showedthat in both general anaesthesia groups, NIDDM and control,blood glucose and serum cortisol concentrations increased significantlyduring surgery, before returning to normal by 4 h after operation;in both local anaesthesia groups, glucose and cortisol concentrationschanged little during surgery. Serum insulin concentrationsincreased 30 mm after operation to coincide with the peak ofthe glucose increase in the non-diabetic patients who receivedgeneral anaesthesia, but no insulin response was seen in thediabetic general anaesthesia patients. Blood glucose and insulinconcentrations increased in patients who received local anaesthesia(NIDDM and controls) when they ate after operation. The resultsshow that cataract surgery under local anaesthesia providesimproved metabolic control for the diabetic patient. Its usemaintains glucose homeostasis, prevents the increases in cortisoland glucose which are seen under general anaesthesia and obviatesthe need for postoperative starvation. (Br. J. Anaesth. 1995;74: 500–505)     

The use of epidural analgesia in a New Zealand tertiary hospital before and after publication of the MASTER study

We audited the total number of perioperative epidural techniques performed at Christchurch Hospital, New Zealand, for three years, before and after The Lancet published the MASTER Anaesthesia Trial in 2002. We also looked specifically at the number of epidural anaesthetic and analgesic techniques performed in combination with general anaesthesia for colonic surgery over the same period. In both cases we found a statistically significant fall in epidural rate in the years after the publication (P < 0.001). A subsequent survey of local specialist anaesthetists, who have worked throughout this period, revealed the majority (75%) were knowingly performing fewer epidural techniques and that the findings of the MASTER Anaesthesia Trial had influenced their decisions.     

Recurrence of focal seizure activity in an infant during induction of anaesthesia with sevoflurane

A three-month-old male infant, previously diagnosed with seizures with a focal origin induced by hypocalcaemia secondary to hypoparathyroidism, presented for right cataract surgery. The hypocalcaemia and seizure activity had resolved with medical therapy, with normal calcium levels and no seizures for a month. Anaesthesia with halothane and isoflurane for left cataract surgery two days previously had been uneventful. During induction of anaesthesia with sevoflurane for the right cataract surgery, the patient had a focal seizure similar to those previously occurring when the patient was hypocalcaemic. The patient had normal calcium levels at the time of surgery. It appears likely that sevoflurane had triggered seizure activity in the apparently controlled focus. The potential for sevoflurane to induce epileptogenic activity in patients with reduced seizure threshold is discussed.     

Outcome of high-volume cataract surgery at an academic hospital.

OBJECTIVE: This study aimed to review the results of high-volume cataract surgery performed at Umtata General Hospital, an academic hospital, during an 'eye surgery camp' held over a weekend. SUBJECTS AND DESIGN: Ninety-eight cataract operations were performed over 3 days at Umtata Hospital during an eye camp to reduce backlog of cataract surgery in the Eastern Cape. After media announcement, patients were selected for cataract surgery and comprehensive pre-operative evaluation was done. Three qualified surgeons operated on the patients. OUTCOME MEASURES: Patients were reviewed at day 1 and at 3- and 6-week intervals in order to study the outcome of such operations. RESULTS: A total of 92.4% of patients achieved visual acuity of 6/60 or better at 6 weeks postoperatively. The surgical complication rate was minimal and overall satisfactory surgical outcome was observed in these cases. CONCLUSION: Teaching hospitals with dedicated ophthalmic operating facilities can be utilised for high-volume cataract surgery over designated short-term periods and can provide a good alternative to mobile eye camp surgery. Until primary and secondary care facilities are optimal for cataract screening and surgery, such camps are recommended to reduce backlog of cataract surgery in the country.     

A prospective observational study of the subjective experience of caesarean section under regional anaesthesia

The aim of our study was to determine the subjective sensation of caesarean section under regional anaesthesia. We performed a prospective, observational study of 205 patients undergoing caesarean section under regional anaesthesia in a UK district general hospital. Patients were asked open and closed questions relating to their physical and emotional experience during the operation. Seventy-three percent of patients chose the phrase "pulling and pushing" to describe the physical sensation of the operation, 75% described the experience as pleasant, and only 4% described it as unpleasant, the rest saying it was neither pleasant nor unpleasant. Ninety-six percent said they would by choice have any future caesarean section under regional anaesthesia, 3% were undecided and 1% said they would prefer a general anaesthetic next time. This study provides important precise information that may be given to patients before caesarean section under regional anaesthesia. We believe it will help minimise preoperative fears and increase patients' ability to make informed decisions about their care.     

Anaesthesia related mortality data at a Tertiary Pediatric Hospital in Western Australia

Background

Anaesthesia related mortality in paediatrics is rare. There are limited data describing paediatric anaesthesia related mortality. This study determined the anaesthesia related mortality at a Tertiary Paediatric Hospital in Western Australia.

Methods

A retrospective cohort study of children under-18 years of age, that died within 30-days of undergoing anaesthesia at Princess Margaret Hospital (PMH), between 01 January 2001 and 31 March 2015. A senior panel of clinicians reviewed each death to determine whether the death was (i) due wholly to the provision of anaesthesia (ii) due partly to the provision of anaesthesia or (iii) if death was related to the underlying pathology of the patient and anaesthesia was not contributory. Anaesthesia related mortality, 24-h and 30-day mortality as well as predictors of mortality were determined.

Results

A total of 154,538 anaesthetic events were recorded. There were 198 deaths within 30-days of anaesthesia. Anaesthesia attributable mortality was 0.19/10,000 with all anaesthesia deaths occuring in patients undergoing cardiothoracic surgery. The 24-h and 30-day all-cause mortality rate was 3.43/10,000 (95% CI 2.57–4.49) and 9.38/10,000 (95% CI 7.92–11.04), respectively. Overall mortality was 12.34/10,000 (95% CI 11.09–14.73) Age less than 1-year, cardiac surgery, emergency surgery and higher ASA score were all significant predictors of mortality.

Conclusion

Paediatric anaesthesia related mortality as reflected in this retrospective cohort study is uncommon. Significant risk factors were determined as predictors of mortality.     

Can the Iowa Satisfaction with Anesthesia Scale be used to measure patient satisfaction with cataract care under topical local anesthesia and monitored sedation at a community hospital?

Patient satisfaction ratings provide a means to evaluate and monitor quality of health care. We tested the ability of the Iowa Satisfaction with Anesthesia Scale (ISAS) to measure satisfaction with cataract care under topical local anesthesia and monitored sedation given by an anesthesiologist at a community hospital. Three hundred six patients were administered the ISAS along with alternate ratings of quality of care and patient satisfaction. There were no incomplete questionnaires. The ISAS demonstrated reasonable reliability (Cronbach's alpha = 0.68; test-retest = 0.48-0.67). The ISAS had excellent construct validity; ISAS scores were lower in patients who gave lower ratings of quality (4.98 versus 5.64), who had lower satisfaction visual analog scale scores (5.12 versus 5.65), who wanted changes in their care (4.76 versus 5.67), who had suggestions to improve care (5.08 versus 5.63), or who preferred more sedation (4.85 versus 5.66) (P < 0.0001). Our results indicate that the ISAS questionnaire is a feasible, reliable, and valid tool to measure patient satisfaction in patients undergoing cataract surgery under topical anesthesia and monitored sedation.     

Safe sedation practice for surgeons

Sedation may facilitate the acceptance of surgery under local anaesthesia, and improve the patient's experience. However, surgeons should be aware that there is good evidence that sedation has the potential to harm patients. Some authorities believe that patients' protective reflexes are impaired at any level of sedation. Sedation merges into anaesthesia in a continuum of loss of consciousness. All surgeons should understand the definition of ‘conscious sedation’, and be aware of the concepts of ‘deep sedation’ and ‘monitored anaesthesia care’, which are prevalent in the USA. This paper discusses current sedation guidelines in the particular speciality areas where surgeons may be involved, the evidence for patient complications with sedation, and safe sedation practice.     

Levobupivacaine 0.75% vs. lidocaine 4% for topical anaesthesia: a clinical comparison in cataract surgery

BACKGROUND: The aim of this study was to compare the efficacy of topical levobupivacaine drops 0.75% vs. lidocaine drops 4% in cataract surgery. METHODS: We examined 203 patients undergoing cataract surgery by phacoemulsification. They were randomized into two groups: one received four drops of lidocaine 4% and the other received four drops of levobupivacaine 0.75%. The onset and offset times of sensory block were evaluated. Application, intraoperative and postoperative subjective pain was quantified by the patients using a verbal pain score. Complications, rates of supplemental anaesthesia, and the satisfaction of surgeon and patients were also recorded. RESULTS: The mean sensory onset and offset times were significantly higher for the levobupivacaine group (P < 0.01). Pain score was lower in the levobupivacaine group than in the lidocaine one and the difference was statistically significant at all stages (P < 0.01). The mean satisfaction scores of patients and surgeon were also statistically higher for levobupivacaine (P < 0.01). No significant differences for complications and rates of supplemental anaesthesia were found. CONCLUSIONS: Topical levobupivacaine 0.75% shows the same efficacy and safety as lidocaine 4% in cataract surgery by phacoemulsification. There was an adequate block with a good level of satisfaction of surgeon and patients. Levobupivacaine 0.75% offers a new and acceptable choice for topical anaesthesia in cataract surgery.