LOCAL ANAESTHESIA FOR CATARACT SURGERY

110 was 24% and by Coustan 22%. This increase is likely to be of pathological significance, and whilst neither group claimed any significant benefit from dietary therapy, Coustan’s non-randoftiised

(4) If No, can we settle for treatment of only those women whose postprandial blood glucose exceeds 9 mmol/1 or fasting levels exceed 7 mmol/l. These are Persson’s criteria, which identify 1 in 6 of

studies and the randomised trial of O’SullivanS revealed a significant reduction associated with prophylactic insulin. On the other hand, the randomised trial of Persson et al6 found no advantage of diet and insulin over diet alone in respect of birthweight or neonatal morbidity. 14% of the diet-treated group in their study were given insulin when the postprandial blood glucose deteriorated significantly. Weiss’ found a rate of 16% fetal hyperinsulinaemia detected by amniocentesis among 359 gestational diabetic patients. This finding raises the possibility that a subgroup of women with IGT (around 15%) have a hyperglycaemic response with advancing pregnancy and that target-oriented therapy in this group will prevent fetal hyperinsulinaemia. Treatment of the remaining 85% may be unnecessary-and if it takes the form of insulin, treatment is inconvenient and possibly hazardous. The figure shows birthweight for gestational age in IGT in a recent consecutive series of 40 women at this hospital. Our treatment regimens, like others’, tend to be ad hoc, diet and/or diet and insulin being used depending on profile plasma glucose levels. We are unable to use either the diagnostic 2 h glucose in glucose tolerance testing or the mean pre-delivery glucose to predict macrosomia (figure). As in those studies reviewed by Kalkhoff$we found an absence of macrosomia in our insulin-treated group, with no correlation with diurnal plasma glucose.

women

with IGT.6

Department of Obstetrics and Gynaecology, University of Sheffield, Clinical Sciences Centre, Northern General

Hospital,

Sheffield S5 7AU

ROBERT B. FRASER FIONA A. FORD CHRISTINE BRUCE

K, Kjellmer I. The outcome of diabetic pregnancies in relation to the mother’s blood sugar level. Am J Obstet Gynecol 1972; 112: 213-20. 2. WHO Study Group. Diabetes mellitus. Tech Rep Ser WHO 1985; no 727. 3. Li DFH, Wong VCW, O’Hoy KMKY, Yeung CY, Ma HK. Is treatment needed for mild impairment of glucose tolerance in pregnancy? A randomised controlled trial Br J Obstet Gynaecol 1987, 94: 851-54. 4. Coustan DR. Management of gestational diabetes. In: Reece EA, Coustan DR, eds Diabetes mellitus in pregnancy. Edinburgh- Churchill Livingstone, 1988: 441-52 5. O’Sullivan JB. Prospective study of gestational diabetes and its treatment. In Sutherland HW, Stowers JM, eds. Carbohydrate metabolism in pregnancy and the newborn. Edinburgh Churchill Livingstone, 1975; 195-204. 6. Persson B, Stangenberg M, Hansson U, Nordlander E. Gestational diabetes mellitus (GDM). Comparative evaluation of two treatment regimes: diet versus insulin and diet. Diabetes 1985; 34 (suppl 2): 101-05. 7 Weiss PAM. Prophylactic insulin in gestational diabetes. Obstet Gynecol 1988, 71: 951. 8. Kalkhoff RK Therapeutic results of insulin therapy in gestational diabetes mellitus Diabetes 1985; 34 (suppl 2) 97-100. 1. Karlsson

SiR,—Your editorial Glucose Tolerance in Pregnancy: the Who and How of Testing covers the controversial areas but does not resolve them. You criticise American diagnostic strategies as "very complex, time-consuming, and expensive". We disagree. The Second International Workshop-Conference on Gestational Diabetes Mellitus1 greatly influenced American thought and practice. The American Diabetes Association statement endorsed the recommendations of that conference.2 All pregnant women should be screened at 24-28 weeks with a 50 g glucose drink and 1 h blood glucose measurement, the O’Sullivan and Mahan criteria being used for diagnosis. These practical, cost-effective principles are embraced in guidelines from the Centers for Disease Control, the American College of Obstetricians and Gynecologistsand here in Michigan by the Department of Public Health. The protocol you recommend is too vague to provide the average clinician with sufficient guidance. For instance, what is the best time to test for gestational diabetes? What is an abnormal screening blood or urine value? What risk factors are suitable to prompt a provocative screening test? You rightly stress the need to avoid missing overt diabetes present early in pregnancy. However, urine tests for glucose are history; blood tests are required. Rather carping at a diagnostic protocol that is widely accepted in the United States your editorial would have served patients better by endorsing it. Division of Metabolic Diseases, Henry Ford Hospital, Detroit, Michigan 48202, USA

1.

J. DAVID FACHNIE FRED W. WHITEHOUSE

Summary and recommendations of the Second International Workshop-Conference on Gestational Diabetes Mellitus. Diabetes 1985, 34 (suppl 2): 123-26.

2 American Diabetes Association Gestational diabetes mellitus Ann Intern Med

1986;

105: 461.

40 consecutive

cases

of IGT by WHO criteria.

Upper: birthweight for gestational age and diagnostic 2 h blood or plasma glucose levels. Lower: birthweight for gestational age and mean profile plasma glucose. .

=

diet-treated and A

=

insulin-treated and diet-treated.

There are questions about minor abnormalities of carbohydrate metabolism in pregnancy to be answered before the case for elaborate screening can be accepted: (1) Is IGT without diurnal hyperglycaemia a biochemical abnormality of genuine pathological significance-ie, an independent predictor of fetal hyperinsulinaemia? (2) If Yes, can its pathological effects be identified and successfully treated or prevented? (3) If Yes, is a suitably sensitive and specific screening test available which is capable of widespread application?

LOCAL ANAESTHESIA FOR CATARACT SURGERY

SIR,-Most cataract surgery in the United Kingdom is done under general anaesthesia. The majority of patients are elderly and this age group is at higher risk of complications from general anaesthesia. In the United States and Scandinavia local anaesthesia for cataract surgery is more widely used. In a waiting-list initiative called "Operation Cataract" in Canterbury and Thanet Health District, 100 patients (72 women, mean age 73years: 28 men, mean age 69-9 years) had their operations under local anaesthesia. Since many doctors, nurses, and administrators expressed reservations at the thought of eye surgery with the patient conscious, we asked all patients to complete a short questionnaire

postoperatively. The operations were done by a team of five ophthalmic surgeons who themselves administered retrobulbar and facial blocks

to

their

111

patients.

There

were no

complications associated with the local

anaesthesia. All patients were offered a mild sedative preoperatively

temazepam) and 10 accepted. The injection of local anaesthesia caused varying levels of discomfort: 31 reported "no pain", 49 "slight pain", 8 "painful", and 12 "very painful". When asked about awareness during the operation, 29 patients reported visual sensations, most commonly lights, rainbow colours, and image of an eye (presumably their eye reflecting in the operating microscope); "fmgers and instruments" were mentioned by 3 patients. 87 patients reported hearing talking during the operation, but only 3 found this distressing. During the operation, apart from when the patient was obviously asleep, the nurses and surgeons talked to the patient to provide reassurance. The operation lasted from 20 to 50 minutes. Overall 69 patients reported that they were not nervous during the operation, 24 stated they were nervous, and 7 said that they were very nervous. These levels of anxiety were not related to pain experienced with the local anaesthesia or visual/ auditory sensations during the operation. Although we had no general anaesthesia controls with which to compare our findings, there were 24 patients who had had cataract (10

mg

surgery done on their other eye under general anaesthesia. 20 (83%)

preferred local anaesthesia, 3 (13%) preferred general anaesthesia, and 1 expressed no preference. All the operation cataract patients made a good postoperative recovery. 57 had a cup of tea within 15 minutes of the operation and 77 had taken refreshment within an hour. Within 6 hours patients were taken by minibus with a nurse escort to a hotel 18 miles away, where they stayed for 3 days under medical and nursing supervision. stated that they

This favourable response to the use of local anaesthesia for is encouraging. With the advantages of lower cost, less preoperative patient preparation, and a shorter postoperative recovery period in hospital, there is a case for extending the use of local anaesthesia for cataract surgery in the National Health Service. cataract surgery

St Thomas’ Hospital, London

SAL RASSAM

Canterbury and Thanet Health Authority, 3 Royal Crescent, Ramsgate, Kent CT11 9PF

HUGH F. THOMAS

Medicine and the Law as of July 1, 1989, resident hours other than in the emergency department will be limited to 24 continuous hours within the hospital, with a maximum of 80 a week averaged over four weeks. Clinical tours of duty must be separated by at least 8 non-working hours and senior physicians will be required to be on duty in hospital 2-4 hours per day so that they can supervise house staff. There are also provisions for reviewing residents’ qualifications and experience to decide what procedures they are capable of undertaking with and without supervision. On occasion, defensive

that

Monitoring Equipment and Anaesthetic Failures STRICTER practice standards observed by anaesthetists in Massachusetts have reduced the risk of hypoxic injury-and these anaesthetists have been rewarded by a 20% reduction ($5000 a year on average) in insurance premiums.’ In the USA insurance premiums are loaded according to specialty, unlike in the UK. However, the Medical Protection Society plans to introduce differential premiums in mid-1989. Strict practice standards for anaesthesia developed at Harvard2 were broadly accepted by the American Society of Anesthesiologists (ASA) in 1986, and in July, 1987, these standards

adopted by the Massachusetts Medical Malpractice Joint Underwriting Association (JUA). The ASA standards require rigorous monitoring, including the continued presence of were

an

anaesthetist

or

nurse

anaesthetist

and

the

use

of

electrocardiographic (ECG) monitors, pulse oximeters, and capnographs. Since the JUA standards programme came into effect four claims for hypoxic injury have been filed, all in the last six months of 1987 and before many anaesthetists had agreed to comply with the scheme. In the first eleven months of 1988 not one claim relating to hypoxia has been filed. The 3 anaesthetists who have refused (as a matter of principle) to abide by JUA standards will pay the full class V premium of$24 268, equivalent to that paid by general surgeons. The 317 who have complied are on course for further savings since from July 1, 1989, they will as a group be reduced to class IV (alongside urologists, paying$16 987 for$1-3 million cover) and will still receive a 20% discount. By July, 1990, anaesthesia may be regarded as low risk (class III), as are general practitioners who do limited surgery (now$12 134 per annum). The lesson from the Massachusetts experience is that stricter practice standards can improve safety for patients. This lesson has been learned elsewhere in the USA. In New York State, regulations have been proposed which will require specific monitoring devices to be used during anaesthesia. They have been endorsed by the State Hospital Review and Planning Department and only await the approval of the Department of Health. The revised code is not restricted to anaesthetic monitoring but is a response to the Libby Zion case,3where a patient died after treatment in hospital by exhausted junior doctors. The revised NYS Hospital Code states

medicine may mean better medicine. In three fatal anaesthetic incidents recorded by English coroners4 adoption of these standards might have led to a different outcome. In one the anaesthetist had left the operating-theatre; in the other two cyanosis might have been detected had a pulse oximeter been used. Many deaths and injuries might be avoided if Britain’s hospitals were better equipped with monitoring devices-indeed in the UK some authorities urge that ECG monitoring be used in every anaesthetic.’ However, there is no mechanism for enforcing standards such as the Recommendations for Standards of Monitoring during Anaesthesia and Recovery published by the Association of Anaesthetists of Great Britain and Ireland (1988). A step in this direction was taken on Nov 9, 1988, by a sheriffs inquiry into the death of a girl who had a cardiac arrest while having teeth extracted under halothane anaesthesia. The sheriff said that her death might have been avoided if an ECG has been used, if a nurse trained in resuscitation techniques had been present, and if 100% oxygen had been given by endotracheal tube immediately. The sheriff said that urgent consideration should be given by the authorities to the adoption of these practices whenever a general anaesthetic is administered in a dental clinic or surgery. On Sept 22, 1987, four lower molars were extracted from an 11-year-old girl at the Stewart Laidlaw Dental Clinic in Glasgow. The anaesthetic was nitrous oxide, oxygen, and halothane, via a standard inhalation technique. After the third tooth had been extracted the halothane was stopped and when the fourth tooth had been removed the mask was taken off. The child was then breathing easily but when her breathing became shallow and intermittent the anaesthetist tipped the chair back to maintain blood pressure, gave oxygen via a face mask, and rubbed her sternum. This caused an intake of breath but no movement. Her pulse weakened, and he tipped the chair so that her head was below her feet. There was still some slight respiration. The child was placed on the floor; her

1 McGinn PR. Practice standards leading to premium reductions Am Med News Dec 2,

1988

Eichhorn JH, et al. Anesthesia practice standards at Harvard J Clin Anesth 1988; 1: 55. 3 Brahams D Excessive hours of work. Lancet 1988, ii: 56.

2.

4 Brahams D Three anaesthetic deaths. Lancet

1988, ii: 581 5. Lunn JN, Mushm WW. Mortality associated with anaesthesia London Nuffield Provincial Hospitals Trust, 1982: 48.