Treating Diabetes on a Coronary

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Care Unit Patricia Lamb SRN Clinical Nurse Specialist General Hospital, Birmingham, B4 6NH

The Cardiac Care Unit (CCU) of the General Hospital, Birmingham, was established in 1966, moving to its present purpose-built site in 1975. It is a six- bedded open-plan unit with emergency pacing facilities available and adjoins the Intensive Care Unit. The departments are staffed separately but expertise may be shared.

All patients suspected of myocardial infarction, regardless of sex, age or general condition, are admitted under the care of their consultant physician. Advice and assistance on management may be obtained from the cardiac team of the hospital. A member of this team is available a t all times and visits the Unit each day. Staffing of the CCU consists of a Clinical Specialist, three sisters and eight other trained nurses - registered general or enrolled. Student nurses, up to a maximum of four at any one time, gain experience in the spe’ciality.

453 diabetic patients with proven myocardial infarction have been admitted to CCU since its inception 18 years ago. Patients spend at least 48 hours there before transfer to a general medical ward. Patients with serious disrhythmias, heart block or cardiac failure remain for longer periods of time.

Each patient’s electrocardiograph is displayed at the bedside and on a central monitor, which has freeze and write-out facilities. Diamorphine hydrochloride 5- lOmgs intravenously or intramuscularly is given for pain relief in the initial management. Early mobilisation is encouraged; this promotes well-being and reduces the risk of thromboem- bolism. The patient in left ventricular failure may find resting in a chair more beneficial even on the day of admission.

An early rapport is essential between staff, patient and relatives. The initial explanation must be repeated the next day as little is remembered in those early emotional moments.

Treatment of diabetes Myocardial infarction in diabetes is

often accompanied by poor diabetic control. The Figure shows midday blood glucose following myocardial infarction in ten consecutive patients. Until 1981, the policy had been to administer insulin in divided doses to cover the period of x u t e admission, unless diabetic control

40

was satisfactory on carbohydrate restriction only. A number of different regimens were used, reflecting fashions in diabetic management and enthusiasms of particular medical staff. Such an approach had disadvantages for the nursing staff of the Unit when it was necessary to establish who was the patient’s physician, in order to follow a specific treatment regimen.

In order to develop a more uniform approach to the management of diabetes after myocardial infarction, in 1981 we introduced the use of a low-dose insulin infusion regimen, initially developed in the management of diabetic ketoacidosis and subsequently extended to control of blood glucose in labour and surgery. All diabetic patients who experience an episode of ischaemic pain, of at least thirty minutes duration, are treated

similarly. Both the medical and nursing staff explain to the patient the possible need and reasons for a change in manage- ment of h idher diabetes. Obviously, it may be very alarming for a patient, previously treated by diet o r taking tablets, if he believes insulin may be required on a permanent basis.

Procedure An indwelling cannula is inserted and

connected to a three-way tap. Venous blood is withdrawn and blood glucose estimated by the nursing staff, using a Hypocount machine. If the blood glucose is greater than Smmol/l, an insulin infusion is commenced via a second cannula, using a Braun infusion pump. Solution for infusion is made up of 48ml aliquots of 45ml normal saline, 2.5ml 10% human albumin and 16 units

0 0

DAYS AFTER INFARCTION 1 2 3 4 5 6 7

Figure. Midday blood glucose after myocardial infarction

Practical DIABETES November 1984 VoS 1 No

ReuiQus- Treating Diabetes on a Coronary Care Unit

TABLE. Insulin Infusion Rates for Blood Glucose Ranges

Glucose Insulin Flow Rate mrnol/l u/hr rnls/hr

0-8 1 3 8-1 2 2 6

12-24 4 12

Actrapid insulin. We prefer to use albumin as a “carrier” in solution, to minimise the problem of absorption of insulin by the administration set. The rate of infusion is determined by the blood glucose concentration according to a pre-determined protocol (Table).

Management of blood glucose greater than 24mrnoVl is discussed on an individual basis and infusions may be increased to eight units/hour, but usually most respond to a regimen of insulin infused at four units/hour.

Blood is withdrawn for analysis by the nursing staff at the following times: hourly for the first four hours, and thereafter Chourly for 24 hours after admission. On the second, third and fourth days blood samples are taken at 0800, 1200, 1600 and 2200 hours. Blood glucose measurements are repeated between 0200 hours and 0300 hours in those patients still requiring four units/hour of insulin after the initial twenty-four hours.

It is important to train staff correctly and assess their ability in blood glucose measurement. The accuracy of the Hypocount meter and of the nurses is checked weekly by analysing duplicate samples of blood, one assayed by our own method and the other by a glucose assay by the Department of Clinical Chemistry. Results are displayed in the Unit. Nurses are trained in the skills of taking blood from cannulae and estimating blood glucose, in line with the extended-role-of-the-nurse policy of this District. Venous blood samples may be replaced by thumb pricks, using an Autolet for estimating blood glucose after the initial forty-eight hours.

At the end of at least forty-eight hours the first dose of subcutaneous insulin is given and the infusion is discontinued th i r ty minutes before breakfas t . Subcutaneous insulin is continued twice daily. Subsequently diabetic manage- ment is decided individually but the majority of patients remain on insulin until at least a month after discharge.

During the acute phase of his illness, the diabetic patient may be unable to maintain his normal carbohydrate intake. He may experience nausea, orjust be unwilling to eat. Control of diabetes by constant insulin infusion allows him freedom to choose when he may eat and is not determined by the amount of insulin given previously that day. Those patients eating normally have their

normal diet reduced by 20 grams of carbohydrate to compensate for their reduced energy requirement. The management of diabetes in this way has proved safe and effective, to the extent that it has been incorporated into routine clinical practice on the Unit.

Results The results of an initial pilot study of

26 patients have been published (Ref 1). The mean age of the 26 patients was 63 years (range 44-80): 22 were men, 5 were insulin-dependent, 18 took oral hypo- glycaemic agents and three were treated by diet alone. 20 of these patients sustained myocardial infarction and 6 had angina. The median time from the onset of infarction to the beginning of the infusion was 5 hours (range 1-48 hours).

Six of the 26 patients died as a result of severe heart failure due t o large myocardial infarction. The median date of death was four days after infarction (range 2-50 days).

T h e a v e r a g e b l o o d g l u c o s e concentration on admission to the Unit was 15mmol/l, although a number of patients had blood glucose concent- rations greater than 30mmol/l. Over the first 12 hours of infusion, blood glucose fell to 7.6mmoV1, with considerably less variation between patients (an advantage of the infusion protocol, which has graduated insulin infusion rates for different blood glucose levels, is that high blood glucose concentrat ions are brought down quicker than those which’ start lower. In nearly all patients, a smooth fall in blood glucose is obtained). The necessary infusion rate averaged 3.4 units/h on admission and 2.1 units/h at 12 hours.

In the 10 patients who had glucose values greater than 15mmol/l on admission, this fell steadily from a mean of 24.6mmoVl to a mean value of 9.4rnmoVl at 12 hours. In all 10 patients, the glucose fell readily, although in 3 patients we elected to use higher infusion rates (8-10u/h) for the first three hours.

16 patients had blood glucose concent- rations below 15mmol/l on admission. Except for one patient, all subsequent blood values remained below 15mmol/l over the first 24 hours. The one exception showe rl a transient rise in blood glucose value before falling to below the admission value at four hours.

We maintained the infusion for the following three days and blood glucose

values were maintained between 5 and lOmmoV1, using insulin infusion rates from 1.8 to 2.5 u/h.

Symptomatic hypoglycaemia occurred on single occasions in four patients. In each case svmptoms were mild and were not acco npanied by angina, arrhy- thmias, or I,CG changes. During the first four days, a total of 423 glucose estimations were made, of which 20 (4.7%) were below 3.0mmoVI.

General advice Patient a n d relatives must be

supported with advice and teaching regarding management whilst in hospital and on transfer to the ward and eventual discharge. A refusal to accept the situation, aggression, resentment and depression are all common reactions experienced by patients and relatives alike. The diabetic, who already feels penalised, sees it as yet another complication of his condition and needs to be convinced he has a future both in his family and in society.

The need to stop smoking must be emphasised. Any change in diet pattern or diabetic management is explained and practised. Response to exercise may be determined by brisk walking around the ward, and climbing at least one flight of stairs.

Going home can be very emotionally stressful, particularly to those who have relied heavily on hospital staff because of rhythm disorders or heart failure. The first day at home should be planned to be quiet and visitors kept to a minimum. Activities should be spaced out during the day, avoiding exercise before and immediately after meals and allowing time to rest and relax. Regular sleep p a t t e r n s s h o u l d be es tab l i shed . V e n t u r i n g o u r in e x t r e m e s of t e m p e r a t u r e s h o u l d be a v o i d e d , particularly on cold windy days.

The importance to the patient of the need to take drugs regularly must be emphasised, with reminders of the problems that can occur if this is ignored. Some patients may worry that extra medication could have adverse effects on their diabetes. At a later stage in recovery, it is important to assess the need to continue drugs prescribed in the acute phase of the illness. Too often, patients are left on diuretic therapy or digoxin long after they ceased to be needed. At this stage, blood pressure should be measured, since in hyper- tensive patients this may fall during the acute phase of the myocardial infarction and a rise may only now be apparent. Finally, this may be an ideal opportunity to discuss patients’ worries and fears. Resumption of sexual activity will vary, depending on age, previous habits, and complications of his illness. It is generally believed that in the absence of fztigue or emotional stress, the cardiovascular

41 Practical DIABETES November 1984 Vol 1 No 2

response to intercourse with a regular partner is relatively similar to climbing one or two flights of stairs.

Physiotherapy The great fear that any activity may

result in further pain is a very real problem. Exercise needs to be assessed individually, whenever possible, and the advent of post-coronary exercise classes has helped considerably to this end. Classes need not be sophisticated and can be simple and inexpensive to organise. In this hospital, exercises are supervised by two physiotherapists and two nurses, one of whom is trained in the use of the defibrillator. The dietitian frequently visits to give advice. Patients aged less than sixty years who have sustained myocardial infarction or severe angina are encouraged, whilst in the ward, to attend a programme of graded exercises.

Af te r the i r ini t ia l ou t -pa t ien t appointment at one month, patients attend the gymnasium twice-weekly from 1515-1600 hours. Spouses are welcome. A copy of the exercises are taken home and the patient is encouraged to continue the exercises daily and advised to ring the nurses on the CCU if any problems occur. To date, we have not encountered particular problems in diabetic patients attending the exercise class, although our

Treating Diabetes on a Coronary Care Unit

numbers are small. The experience of other groups suggest that diabetics attending post-infarction exercise classes may encounter difficulties. Until more experience is gained, diabetic patients should be supervise,’ by someone with specialist knowledge and CCU facilities should be readily available.

There seems little doubt that patients benefit psychologically from this form of group teaching and often surpass their previous level of physical activity. General improvement often results from meeting others similarly afflicted and from comparing progress. Nurses can help considerably by just being prepared to listen and recognise simple fears, social needs and early signs that changes in medical treatment might be beneficial. Extra carbohydrate is on hand in the gymnasium for the diabetic patient but hypoglycaemia has not been a problem.

Unnecessary delay in return to work may frequently be due t o well- intentioned but over-cautious and misguided advice from doctors, friends and relatives. Patients with uncomp- licated myocardial infarctions should have returned to work by eight weeks. After careful assessment, a return to accustomed work should be encouraged whenever possible, even in the case of occupations which involve physical

exertion, as this signifies a return to good health for the individual.

Conclusion The management of the diabetic

patient after myocardial infarction is a challenge. In the short-term, the metabolic response to infarction has profound implications for the diabetic patient, not least of which is the resultant hyperglycaemia. This must be controlled and the low-dose insulin infusion regimen achieves this in a simple, safe and effective way. In the longer-term, the mortality in diabetic patients remains 1.5-2.0 times that of non-diabetic patients. Sadly, we have not observed a fall in this with our change in manage- ment (Ref 2). The reasons why this should be so are discussed elsewhere in this issue. A reduction in mortality remains our ultimate goal.

References (1) Gwilt D J, Nattrass M, Pentecost B L.

Use of low-dose insulin infusions in diabetics after myocardial infarction. Br Med J , 1982; 285: 1402-4.

(2) Gwilt D J, Petri M, Lamb P, Nattrass M, Pentecost B L. Effect of intravenous insulin infusion on mortality among diabetic patients after myocardial infarction. Br Heart J , 1984; 51: 626-30.

I with-G I ucoc he k II - the diabetic’s best friend Records are important. That’s why we supply every GIucochekJIwith the special wallet incorporating the personal logbook and pencil. The diabetic can thus directly document his test result history for periodic discussion with his physician.

Incidentally, that’s not why he chose Glucochek II. It also happens to be the most advanced, easy to use, accurate and complete, instantly usable pocket meter ever developed for blood glucose level monitoring, anywhere.

And at underf8O no diabetic orphysician needs to settle for anything less, at any price. Medistron Ltd 6 Lawson-Hunt Industrial Park Broadbridge Heath HORSHAM W. Sussex RH12 3JR

42 Practical DIABETES November 1984 Vol 1 No 2