Ординатура / Офтальмология / Английские материалы / Small Incision Cataract Surgery (Manual Phaco)_Singh_2002

16.MC Leod, James CR: Viscodelamination at the vitreoretinal juncture in severe diabetic eye disease. Br J Ophthalmol 72: 413, 1988.

17.Mital RN, Tiwari R: Suprachoroidal injection of sodium hyaluronate as an “internal” buckling procedure. Ophthalmic Res 19: 255, 1987.

18.Momose a and Kasahara A: Methylcellulose: A better visco surgical alaternative for intraocular lens implantation. Ind J Ophthalmol 37: 64-66, 1989.

19.Nuyts RMMA, Boot N, V Best JA et al: Long-term 351-9 changes in corneal endothelium following toxic endothelial cell destriction. A specular microscopic and fluorometic study.

Br J Ophthalmol 80: 15, 1996.

20.Passo MS, Emest JT, Goldstick TK: Hyaluronate increases intraocular pressure when used in cataract extraction. Br J Ophthalmol 69: 572-75, 1985.

21.Pocker AJ, Mc Cuess BW II, Autton WL et al: Procoagulant effect of intraocular sodium hyaluronate after phakic diabetic vitrectomy. A prospective randomized study. Ophthalmology 96: 1491, 1989.

22.Probst LE, Nichols BD: Corneal endothelial and intraocular pressure changes after phacoemulsification with Amvisc Plus and Viscoat. J Cataract Refract Surg 19: 725-30 (Medline), 1993.

23.Pruett RC, Schepens CL, Swan DA: Hyaluronic acid vitreous substitute a six year clinical application. Arch Ophthalmol 97: 2325, 1979.

24.Rainer G, Menapace R, Findl O et al: Intraocular pressure rise after small incision cataract surgery; a randomised intraindividual comparison of two dispersive viscoelastic agents. Br J Ophthalmol 85: 139-42, 2001.

25.Rainer G, Menapace R, Schmetterer K et al: Effect of dorzolamide and latanoprost on intraocular pressure following small incision cataract surger. J Cataract Refract Surg 25: 1624-29 (Medline), 1999.

26.Salvo Eugene C Jr, Luntz MH, Medow Norman B: Use of viscoelastics posttrabeculectomy: A survey of members of American Glaucoma Society. Ophthalmic Surg Lasers 30: 271-75, 1999.

27.Sand BB, Marnerk, Norn MS: Sodium hyaluronate in the treatment of keratoconjunctivitis sicca. a double masked clinical trial. Acta Ophthalmol 67: 181, 1987.

28.Searl SS, Metz HS, Lindahl KJ: The use of sodium hyaluronate as a biologic sleeve in strabismus surgery. Ann Ophth 19: 215, 1987.

29.Seiff Sr, Ahn JC: Locating cut medial canaliculi by direct injection of sodium hyaluronate into the lacrimal soc.

Ophthalmic Surgery 20: 176, 1989.

30.Tan AKK and Humphry RC: The dilated fixed pupil after cataract surgery: Is it related to intraocular use of hypromellose. Br J Ophthalmol 77: 639-64, 1993.

31.Vitacoro AA, Vita: Coro AA hyaluronate facilitates passage of lacrimal probes for repair of lacerated canaliculi. Arch Ophthalmol 106: 579, 1988.

Comparison of Various 5

ECCE Techniques

Kamaljeet Singh

Vipin Bihari

Extracapsular cataract extraction (ECCE) can be done by three techniques: • Conventional,

• Manual Phaco, • Phacoemulsification (Table

5.1).

Although in all the three techniques the goal remains the same, i.e. you have to leave behind the posterior capsule and a part of anterior capsule. But since the methods differ the procedure and used gadgets also vary. Following differences can be enumerated in the three methods.

Conjunctival Flap

The conjunctival flap is usually large in ECCE extending from almost 2-3 O’clock to 8-9 O’clock. The conjunctival flap is smaller in manual phaco extending from 10.30 to 1.30 O’clock, if one is very liberal in making flaps. As one gains experience in this surgery the conjunctival flap becomes even smaller. In conventional ECCE one can make corneal incision only and may not need any flap. But this flap is a must in manual phaco, because one needs longer tunnel. In contrast to this in phacoemulsification present trend is to make a corneal tunnel therefore, conjunctival flap is not required. Beginners still prefer to do this surgery through scleral tunnel. Hence they make a flap. Disadvantage of making a big flap is it gives more astigmatism.

Cautery

Its use depends on whether surgeon has made a flap or not. The cautery causes increase in the amount of astigmatism, which goes against the philosophy of giving least possible astigmatism. The larger the conjunctival flap more is the need of cautery. So, the use of cautery is maximum in ECCE, less in manual phaco and minimum in phaco. Cautery is not needed if corneal incision is made as in phacoemulsification.

Incision

This is the most important step in cataract surgery since this gives the ultimate result of surgery. Longer the incision more is the astigmatism; and nearer it is to limbus more is the astigmatism. Therefore, for achieving least astigmatism surgeon should make smallest possible incision in which, he can deliver the nucleus easily, and should remain far from the limbus. Conventional ECCE is done close to limbus and is the longest (10-12 mm) incision; phacoemulsification has the minimum possible wound (3.2 mm) if foldable lenses are used. If non-foldable lenses are implanted the length increases to 5.5 mm taking away the advantage of smallest incision. The incision length in non-phaco SICS is 6 to 6.5 mm. In this regard, both manual phaco and phacoemulsification with nonfoldable IOL are equally comparable.

Viscoelastics

It has been shown in various studies that methyl cellulose is as good as any other viscoelastics. Methyl cellulose is cheap and can be easily removed from anterior chamber. This can be used both in conventional ECCE and manual phaco; though the quantity used is more in manual phaco and less in conventional ECCE. In phacoemulsification many Indian surgeons have repeatedly shown that methyl cellulose is as good as sodium hyaluronate, but still the preferred viscoelastic world over is sodium hyaluronate (healon). Its use increases the cost of surgery immensely.

Capsulotomy

Any type of capsulotomy—can-opener, envelope or capsulorhexis can be made in conventional ECCE and manual phaco. Whereas capsulorhexis is a must in phacoemulsification. This is difficult to learn and makes the learning curve longer, although trypan blue has made life easier for surgeons.

Nucleus Prolapse

This is very important step in manual phaco. Surgeon cannot proceed further if he has not mastered this step. It is not needed both in ECCE and phaco. If nucleus prolapses into anterior chamber in ECCE there is no problem as nucleus delivery becomes easier. But if it happens in phacoemulsification most of the surgeons advocate conversion to ECCE, though some authorities have advocated supracapsular phaco.

Nucleus Delivery

Nucleus delivery is easiest in ECCE since the incision is long and single plane. It is difficult in manual phaco, because one has to deliver the nucleus through tunnel. Moreover, the nucleus has to be divided into smaller pieces by some technique before delivering out. In phacoemulsification, in contrast, the nucleus delivery is through phaco hand piece and is most difficult. The surgery is done mostly in the bag, which depends largely on the quality of the machine, its fluidics, holding power and ultrasonic cutting power.

Cortical Clean-up

Cortical clean-up is easiest in ECCE because nucleus and perinucleus both are delivered out in one go. Remaining portion is cortex only, which can be easily washed manually with the help of Simcoe cannula. Cleaning is slightly difficult in manual phaco because perinucleus and cortex both remain inside AC and only nucleus is delivered, through a small incision. Perinucleus is hydro-extracted by keeping the Simcoe cannula at 6 O’clock and at the same time depressing the tunnel with the same cannula, or is hydroexpressed with the help of AC maintainer. In phacoemulsification the perinucleus and cortical matter are aspirated by automated probe or manually by Simcoe cannula.

Lens Implantation

Non-foldable lenses are used in ECCE and manual phaco. The preferred optic size is 6-6.5 mm in both these techniques, which have several advantages over small optic lenses (used in phaco). These large size lenses do not cause edge glare, do not decentre and do not obstruct in retinal treatment. When foldable lenses are used in phaco the optic size is large 6-6.5 mm. Inserting, a foldable lens is difficult to master as newer techniques keep on coming. Whereas, implanting a non-foldable lens is quite easy.

Sutures

Sutures are usually not needed in phaco as corneal valve is made which automatically closes. But in case the corneal incision has been made and there is need to extend it for implanting even a 5.25 mm optics, suture may be required. For scleral incision, even if the incision is extended to 7.5 mm, sutures are not needed as the tunnel is self-sealing. So both in phaco and manual phaco even if the incision is large there is no need for applying the sutures,. In contrast, ECCE needs 5 to 7 interrupted sutures. When the sutures are applied patient has complaints of foreign body sensation for quite long even if 10.0 suture are used and knots are buried.

Astigmatism

There are several factors responsible for astigmatism. The incision, suture, lens decentration, etc. but, amongst three techniques astigmatism is maximum in ECCE. Usually we get an astigmatism of 1.5 to 3.0 D, but surprise astigmatism up to 7.0 D has been noted. This astigmatism is much less (0.5–1.5 D) in manual phaco and negligible (0 to 1.0 D) in phacoemulsification.

Recovery

Although patient is mobile from the day one in all types of ECCE surgeries, yet visual outcome is not that fast. Because of the time taken for wound healing we give glasses after 6 weeks in ECCE, whereas in manual phaco 15 days is a good period of wait for prescribing glasses. In phaco visual recovery is almost immediate although the glasses are prescribed after 2 weeks.

Complications

There are several complications associated with cataract surgery. We would like to discuss the common and dreaded complications. Corneal decompensation is rarely seen nowadays with ECCE. When we compare, the endothelial cell loss is slightly more in manual phaco than in phacoemulsification, although with the use of good amount of viscoelastics it can be reduced. Posterior capsule rupture occurs in all the three types of surgery but is most common in phaco, especially in the hands of beginners. Chances of posterior dislocation of fragments of lens and even loss in toto are much greater in phaco than the other two techniques. Thus, when we compare manual phaco and phacoemulsification cornea is at greater risk in manual phaco and vitreous and retina in phaco.

Type of Cataract

If the lens is hard perhaps the easiest technique is ECCE, for soft lenses manual phaco gives excellent results and in between these two varieties phaco is quite good.

Age of Patient

In young patients the cataract is very soft hence they are better candidates for both manual phaco and phacoemulsification. As the age advances the lens becomes harder. Beyond 70 years as the cornea is already compromised, ECCE is the choice. There is no hard and fast rule for this. Master surgeons can easily alter the decision.

Surgical Skill

For any surgery surgical skill is very important but perhaps for phaco it is most demanding. The surgeon has to use both the hands, both feet, both ears, other than eyes. Therefore, phaco is highly skilled job along with lot many

things to learn. Whereas, any average surgeon can easily learn ECCE both and manual phaco because no costly gadgets but only skilled hands are required and the surgery is not machine dependent.

Microscope

ECCE and manual phaco can be done with any average microscope. But for phaco the surgeon should have the best possible microscope, as the stereopsis should be excellent. Focussing and zoom both should ideally be foot controlled. These two things increase the cost of microscope immensely. In addition, the cost of phaco machine is exorbitant, which an average surgeon from the developing country cannot afford. Foldable lenses and viscoelastics are also costly for phaco. Therefore, in case the cost factor is not involved phaco would be the choice. Otherwise, manual phaco without addition of costly equipment is the best and safest for majority of Indian patients and surgeons.

FURTHER READING

1.Amar Agarwal, Mahipal S Sachdev et al: Phacoemulsification laser cataract surgery and foldable IOLs. Jaypee Brothers: India. 2000.

2.Blumenthal M et al: Small incision manual extracapsular cataract extraction using selective hydrodissection.

Ophthalmic Surg 23: 699-701, 1992.

3.Dada VK, Sandhu N: Management of cataract a revolutionary change that occurred during last two decades. J Ind Med Assoce. 97(8): 313-17, 1999.

4.Mathew Manual nucleo fragmentation and endothelial cell loss. J Cat Refr Surg 23(7): 995-99, 1997.

5.Schein OD, Bass EB et al: Cataract surgical techniques: Preferences and underlying beliefs. Arch Ophthalmol 113: 1108-12, 1995.

6.Vajpayee RB, Sabharwal S, Sharma N et al: Phaco fracture verses phacoemulsification in eyes with age related cataract.

J Cataract Ref Surg 24: 1252-55, 1998.

7.Wright M, Chawla H, Adams A: Results of small incision extracapsular cataract surgery using anterior chamber maintainer without viscoelastic. BJO 83: 71-75, 1999.

The morbidity and mortality rates during the perioperative period are greater in the diabetic compared with the nondiabetic of comparable age, for a number of reasons. Macrovascular disease is

extremely common in both type 1 and type 2 patients. Cardiovascular complications are the major causes of surgical mortality in diabetics (30%). In addition a high percentage (especially in the over 50 age category) have impaired renal function and are prone to fluid and electrolyte imbalance, dehydration, and obtundation. During the postoperative period, the diabetic has a higher incidence of infection at the operative site as well as a greater potential for urinary tract infection, pneumonia, and other systemic infections. Wound healing may be impaired in the setting of persistent hyperglycemia (>240 mg/dl) as a result of modified fibroblast function. This defect, combined with infection, frequently leads to a difficult and protracted hospitalisation and frequent readmission. Consequently, the diabetic patient spends 30 to 50 per cent more time in the hospital than the nondiabetic following surgery, even if the surgery proceeds without incident.

Safety and simplicity are the watchwords of the surgical management of diabetic patients. Safety should be ensured if the following protocols are observed. Simplicity is essential, as surgery is frequently required in diabetic patients and its bedside management is usually undertaken by junior doctors who may have little or no specialized knowledge of diabetes. Treatment regimens should not aim for near normoglycaemia; it has been shown that this does not improve outcome, and the risks of hypoglycaemia are considerably increased. Sensible and practical glycaemic targets are discussed below. Hypoglycaemia is a major hazard of surgery, which is particularly important to avoid, as the surgical or

postsurgical patient may be unaware of this or unable to communicate.

With the use of the modern management protocols, the major outcome measures of surgery (duration of hospital stay, morbidity and mortality) are now comparable in diabetic and non-diabetic patients. It follows that the skill, care and motivation with which diabetic patients are managed—ideally supervised by a diabetic team (where available) are important to the success of surgery.

PRINCIPLES OF MANAGEMENT

Management of the individual patient is determined by the severity and nature of surgical trauma and the duration of perioperative fasting.

Determinants of the management plan and preoperative evaluation:

1.Type of diabetes—type 1 diabetes is associated with absolute need for insulin therapy whereas type 2 diabetes is associated with increased insulin needs.

2.Treatment—diet, oral hypoglycaemic agents (OHA) or insulin. Subjects who are usually managed successfully without insulin need insulin only for major surgery; otherwise, simple observation is generally sufficient.

3.Metabolic status—review blood glucose records and glycosylated hemoglobin (HbA1c) values.

4.Cardiac, renal and cerebral vascular status should be assessed.

5.Surgical details:

a.Minor or major— for purposes of clarity, it is useful to define major surgery as any procedure requiring a general anaesthetic.

b.Type of anaesthesia.

c.Type of surgery—emergency or elective.

d.Postoperative oral intake.

The preoperative evaluation should be done in the office before an elective operation or, less preferably, on the day of admission. History of previous glycaemic control should be reviewed and control should be improved in symptomatic and asymptomatic patients with sustained hyperglycaemia, reflected by a fasting blood glucose (FBG) level higher than 200 mg/dl, high HbA1c values (>10%), or both. Improved control during the perioperative period (blood glucose values between 120 mg/dl and 180 mg/dl) reduces the morbidity from fluid and electrolyte imbalance, decreases the risk of infection, and increases the wound-healing rate. Prior day admission is still indicated for all poorly controlled diabetics (FBG >240mg/dl).

MINOR SURGERY

For patients posted for minor surgery, the OHA and insulin are stopped on the day of the surgery. Once the surgery is over and the patient permitted to resume oral feeds the OHA is started with half the dose which the patient was originally taking. On the second postoperative day full dose of the OHA and/or insulin is started.

SURGERY IN PATIENTS

NOT TREATED WITH INSULIN

A small subset of type 2 patients with acceptable control (FBG < 140 mg/dl, other blood glucose values < 200 mg/dl and HbA1c of 8 to 10%) on diet or OHA may not require insulin. Long-acting sulfonylureas (e.g. chlorpropamide) should be stopped, substituting a shorteracting sulfonylurea, if necessary.

Glycaemic control should be monitored carefully during the period before admission. These patients generally require only close observation. The operation should be scheduled for the morning, if possible. Breakfast and any morning dose of OHA are omitted. Throughout the perioperative period, frequent glycaemic monitoring is required and glucose-containing infusion fluids must be avoided. Sulfonylurea drugs, if used, should be omitted until the first postoperative meal.

This approach is acceptable for a relatively simple and short-lasting (less than 2 hours) surgical procedure. Poorly controlled type 2 patients undergoing major surgery who do not achieve the above glycaemic targets are best managed using continuous glucose and insulin delivery as for type 1 patients, after initial stabilization with insulin, either in hospital or at home.

SURGERY IN INSULIN-TREATED PATIENTS

Indications for Insulin

All patients taking insulin, whether persons with type 1 or type 2 diabetes should receive insulin therapy during the surgical procedure (Table 6.1). It is preferable to take diabetic patients for surgery in the morning as first case.

Table 6.1: Indications for insulin therapy during surgery

Insulin Regimen

The kinetics of subcutaneous insulin absorption is unpredictable and hence not advocated. Normally, the requirement of insulin is 0.3U to metabolize 1 gm of glucose.

Continuous insulin infusion (intravenous) is the most rational and physiologic method for perioperative management. This approach has been shown to be safe, effective, and flexible. Insulin infusion should be started the night before for early morning procedures and for patients needing improved glycaemic control. Otherwise, the patient takes the usual evening dose of insulin or OHA.

In all patients requiring insulin, the insulin infusion must be started at least 2 to 3 hours before the operation in order to titrate to the desired level of control.

There are two basic regimens for administering insulin and glucose. The preferred method uses a separate infusion of insulin and glucose to allow for independent adjustments of each infusion rate. In the ‘separate-line’ system one infusion line is used to deliver 10 per cent glucose solution at 100 ml/h, preferably using an electronic drip-counter, while a syringe-driver pump administers insulin through the other, usually at 2-4 U/h. The insulin infusion can either be given into a separate vein, or ‘piggy-backed’ into the glucose line. This approach provides flexibility and can be rapidly adjusted depending on the hourly variation in blood glucose values.

The alternate method is to combine insulin and glucose as a mixture at a pre-estimated individualized

Table 6.3: Postoperative management of patients with diabetes

•Continue perioperative insulin infusion until food is tolerated, then plan new regimen

•Overlap (30 minutes) the initial subcutaneous dose of regular insulin before stopping infusion

•Type 2 diabetics previously treated with diet and/or OHA: prescribe usual medication if BG <180 mg/dl. Higher BG may require transient regular insulin every 6 hours (premeals) as per blood glucose (bedside monitoring) sliding scale

•Insulin-treated diabetics: Prescribe usual regimen or use prior 24 to 48 hours insulin dosage to develop a new basic dose regimen. The dose selected should be 80 to 100% of the previous day’s total dose. Needs may be higher during persistent stress, infection, pain and steroids

The selected basic dose may be given premeal (breakfast [25%], lunch [25%], and dinner [25%]), as regular insulin and NPH given at bedtime (25%). Aim to keep BG in safe range (120-180 mg/dl).

•Modify the basic dose regularly according to the sliding scale needs. Additional doses of regular insulin may be needed at other times (e.g. 10 PM to 2 AM)

•Establish the most suitable insulin regimen or the patient’s previous regimen before patient discharge

glycaemic control is satisfactory. As soon as the patient is able to eat normally again, the usual treatment regimen can be restarted. Frequent glycaemic monitoring is essential because of the variable effects of surgical trauma and other factors such as inactivity, postoperative infection and changes in medication.

PRACTICALITIES OF MANAGEMENT

1.In some diabetics it may not be possible to control the FBG with a predinner bolus of soluble insulin; resulting in a perpetually high FBG. This cannot be controlled by increasing the soluble insulin predinner as it may result in nocturnal hypoglycaemia. Such a situation requires the addition of a small dose of intermediate-acting insulin at bedtime. For example if the FBG is 200 mg per cent with a dose of predinner soluble insulin of 10 IU, one may attempt to reduce the FBG by increasing the dose to 15 U. However, this may result in nocturnal hypoglycaemia, whereas combining soluble insulin with intermediate-acting insulin in the ration of 2:3 (6U of soluble insulin and

9U of intermediate acting insulin) would lower the FBG.

2.In some type 2 patients because of insulin resistance the blood glucose cannot be controlled with insulin alone. Addition of small doses of OHA is recommended to overcome the resistance (half of the previous daily dose should suffice). On the day of the surgery the OHA is stopped.

3.Type 2 diabetics can be safely switched over to oral drugs after a week.

4.Purified insulins are ideal for short-term use in type 2 diabetics to prevent antigenicity and insulin antibody production.

INTRAVENOUS FLUIDS

1.Dextrose saline/normal saline is used if blood pressure is low or normal. In patients with hypertension and the potential for congestive cardiac failure it is safe to use half normal saline, with central venous pressure monitoring.

2.For normal metabolism about 50 gms glucose is required every 8 hours for energy and to avoid ketosis. To meet this demand at least 1000 ml of 5 per cent glucose every 8 hours will be required.

3.In situations requiring fluid restriction 10 per cent dextrose may be infused instead of 5 per cent dextrose with double dose of insulin. This will take care of the energy requirement and avoid overloading the circulation.

4.To avoid hypokalemia, infusion of Isolyte-M or Pharmalyte-M is alternated with dextrose/dextrose saline particularly when insulin is added to the drip. Electrolytes other than potassium (35 mEq/l) are replenished by this fluid.

MONITORING DURING SURGERY

A vital aspect of care is adequate blood glucose monitoring. This is generally done by nursing staff at the bedside, using glucose-oxidase reagent strips, read either visually or by meter. During intraoperative period the blood glucose should be monitored every hour and less frequently as necessary thereafter. The accuracy of these monitoring methods may be poor, and validation with occasional laboratory measurements may be advisable. All hospitals that use reagent strips for diabetic monitoring should have some form of quality-control system to ensure reasonable accuracy, and all staff involved should be carefully trained in their use. The other alternative is

to estimate the blood sugar in the laboratory by conventional methods. A word of caution is that the blood should not be drawn from the arm that is connected to the infusion line, which may show a falsely high value.

Urine glucose monitoring during surgery is not safe particularly when the patient is on intravenous glucose. The results of urine glucose may be strongly positive when the blood glucose may not be high. A large dose of insulin given based on the strongly positive urine test for glucose may produce deleterious hypoglycaemia.

Emergency Surgery

Emergency surgery is as likely if not more likely in the diabetic than in the nondiabetic subject. Management will depend to a large extent on the metabolic condition of the patient. Surgical emergencies, particularly if there is underlying infection, can cause rapid metabolic decompensation with dehydration, hyperglycaemia, and ketoacidosis. Uncontrolled diabetes may also be precipitated in patients not previously known to have diabetes. The problem necessitating surgery may have led to metabolic decompensation; this should first be corrected if possible, unless the operation cannot be delayed.

Diabetic patients require close attention when admitted for an emergency operation. The first priority is to assess glucose control, level of hydration, and acid-base status. Preoperative management will require an aggressive approach to correct fluid and electrolyte imbalances, reverse acid-base disorders, and optimise blood glucose levels. Separate insulin and fluid infusion systems are excellent for such intercurrent management. The insulin dose (rate per hour) and fluid needs should be tailored to each patient according to the severity of the metabolic decompensation and the patient response. The management of ketoacidosis involves higher insulin infusion rate (0.1 U per kilogram of body weight per

hour). The infusion is generally preceded by an intravenous injection of regular insulin (10 U). Adjustments are then made according to hourly blood glucose levels. Once blood glucose values return to 240 mg/dl, 5 per cent dextrose should be included in the rehydration fluids. Adequate potassium replacement is critical, as is close monitoring of fluid balance, acid-base status, electrolytes, and renal function. Once the patient’s condition is stable for 4 to 6 hours, the operation can generally be performed safely. It is important to note that following reversal of the acute stressful condition lower insulin infusion rates will be required for a given blood glucose level.

Our aim is to make patients safe for surgery. For this we need an understanding teamwork between the surgeon, anaesthetist, and the diabetologist. When the patient is under anaesthesia, “The ideal is to have diabetic therapy supervised by a diabetic team where available” (KGMM Alberti).

FURTHER READING

1.Alberti KGMM: Diabetes and surgery. Anaesthesiology 74: 209-11, 1991.

2.Gavin LA: Perioperative management of the diabetic patient.

Endo Met Clin N Am 21: 457-75, 1992.

3.Gill GV: Surgery in patients with diabetes mellitus. In: Pickup J and williams G (Eds): Textbook of diabetes. London: Blackwell Science Ltd. 12.1-12.7, 1997.

4.Hirsch IB, McGill JB, Cryer PE et al: Perioperative management of surgical patients with diabetes mellitus.

Anaesthesiology 74: 346-59, 1991.

5.Hughes TAT, Borsey DQ: The management of diabetic patients undergoing surgery. Pract Diabetes 1: 7-10, 1994.

6.Alberti KGMM, Gill GV, Elliott MJ: Insulin delivery during surgery in the diabetic patient. Diabetic Care S1: 65-77, 1982.

7.Hutchison AS, Shenkir A: BM strips: how accurate are they in general words? Diabet Med 1: 225-26, 1984.