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Management of the patient with diabetes in the perioperative period.

The worldwide prevalence of diabetes mellitus was recorded at 171 million in 2000 and is expected to more than double by 2030 (WHO 2010), therefore knowledge and awareness of aspects related to patients with diabetes, both medically and surgically, is essential. Complications of diabetes mellitus and the causes of surgically related morbidities are best understood by appreciating the mechanisms of the disease as described below.

What is diabetes mellitus?

Diabetes mellitus is a condition that causes derangement of glucose metabolism, resulting in hyperglycaemia and carbohydrate intolerance.

In the healthy individual, the blood glucose levels are tightly controlled to prevent states of hypo-or hyperglycaemia and the associated complications (Gale & Anderson 2002). This regulation of blood glucose levels occurs in response to insulin, glucagon, adrenaline, cortisol and growth hormone release, and major organs involved include the liver, pancreas and peripheral tissue (Gale & Anderson 2002). Insulin is synthesised in the pancreas and is responsible for the uptake of glucose by the liver, fat and muscles for storage as glycogen. In addition, insulin suppresses glucose production in the liver by means of glycogenolysis (conversion of glycogen to glucose) and gluconeogenesis (production of glucose from glycerol, lactate and amino acids), thus reducing blood glucose levels (Marks 2003).

Many types of diabetes exist, with the most common being types 1 and 2. Type 1 (or insulin-dependent) diabetes mellitus is immune mediated and leads to insulin deficiency through a loss of (3-cells within the pancreas. As a result, insulin administration is necessary as part of its management. Although type 1 diabetes classically presents in children, it does not do so exclusively. Type 2 (or non-insulin-independent) diabetes mellitus in contrast tends to present within the adult population. The pathophysiology involved includes deranged insulin secretion and the development of insulin resistance (Gale & Anderson 2002).

Complications of diabetes mellitus

Poor blood glucose control, particularly over a prolonged time period, is responsible for the complications often associated with diabetes. High blood sugar encourages glycosylation (the binding of glucose to proteins), which impairs function and is irreversible. Osmotic swelling ensues, causing cell damage (Underwood 2002). By means of these mechanisms, macro-and microvascular damage occur alongside nephropathies, neuropathies and retinopathies. Macrovascular damage describes a range of conditions including atherosclerotic vascular disease, myocardial infarction, cerebrovascular events and peripheral vascular disease (Hirsch et al 1991). Complications directly relevant to the perioperative patient with diabetes include the following.

Infection and wound complications

It is widely documented that patients with diabetes have infections, with surgical site infection rates being two to three times higher in patients with diabetes than their non-diabetic counterparts (WHO 2008). Patients with diabetes and poorly controlled blood glucose levels are also more likely to develop infection. This predisposition to infections, in addition to poor peripheral vascularity and neuropathies, all come together to promote sites of infection that often progress to severe stages of ulceration before being addressed (Marhoffer et al 1992, Underwood 2002). Wound healing is suboptimal, with an impaired immune response, delayed fibroblast action and tissue hypoxia, contributed to by atherosclerosis, all factors in the process (Falanga 2005).

Nephropathy and neuropathy

Nephropathies ultimately result in renal impairment or failure: a serious condition that greatly impacts not only on the everyday life of the patient, but also on the surgical procedures and drug treatment options. Decreased renal function places restrictions on the choice of drugs available for use in these patients, which may impact on the optimisation of treatment with regard to other complications. Neuropathic complications include peripheral neuropathy (such as increased incidence of ulceration of the lower extremities) and autonomic neuropathy (Hirsch et al 1991).

Diabetic ketoacidosis

Acute diabetic emergencies include diabetic ketoacidosis which is associated with acidosis, hyperventilation, vomiting and abdominal pain as well as acute confusion. Predominantly patients with type 1 diabetes are affected, often as a result of prolonged disturbance of insulin therapy or due to the stress response evoked during surgery (Walker et al 1989). Management is with fluid resuscitation, initiation of insulin administration and electrolyte replacement as required. Fluid resuscitation must be accurately monitored to prevent fluid overload, pulmonary oedema or cerebral oedema. In contrast, hyperosmolar nonketotic states are seen in patients with type 2 diabetes, commonly presenting with reduced levels of consciousness and dehydration as a result of hyperosmolarity and osmotic diuresis (Marks & Skyler 1996).

Management of diabetes mellitus

The basis of diabetes management is to improve control of blood glucose levels, thus also preventing complications. Advice should be given to patients about the need for regular monitoring of blood glucose levels, reducing body weight if obese and advice on smoking cessation if a smoker. It is important that a tailored diet be advised for the patient, taking into account personal choices, cultural preferences and the caloric requirement for the individual as well as the correct portion of the constituents of carbohydrate, fat and protein (National Collaborating Centre for Chronic Conditions 2008).

Type 1 diabetes mellitus

Alongside a controlled dietary intake, it is important to maintain an appropriate level of physical activity which can reduce the risk of arterial disease in the long term. For those patients who lack insulin production, artificial replacement is essential by means of a soluble biosynthetic human insulin product.

A major concern with the subcutaneous administration of soluble insulin as opposed to intravenous administration is the prolonged time taken for the hormone to reach the circulation and the subsequent longer-lasting effect (Gale & Anderson 2002). Multiple insulin injections are self-administered on a daily basis, with rapid-acting analogues playing a role in glucose control before meals and long-acting analogues for night time (National Collaborating Centre for Chronic Conditions 2010). Rapid-acting insulin analogues have the advantage of reaching the circulation quicker than soluble insulin after administration, and consequently act for a shorter period of time (Cameron & Bennett 2009).

Type 2 diabetes mellitus

Lifestyle measures including diet control and exercise remain a part of the foundation of diabetes management. Oral drugs are then indicated, with first-line treatment as biguanide, followed secondarily by a sulphonylurea. Of the biguanides, metformin is the most commonly used, and is considered to work by inhibiting gluconeogenesis and increasing insulin sensitivity. Unfortunately, metformin use has been associated with the development of lactic acidosis (Gale & Anderson 2002). The use of a sulphonylurea (e.g. gliclazide or tolbutamide) depends on adequate numbers of functioning [beta]-cells in the individual's pancreas, because it works primarily to increase secretion of insulin.

Where sufficient control of glucose still fails to be achieved, insulin is added to the oral regimen, either as a long-acting preparation or as multiple smaller doses (National Collaborating Centre for Chronic Conditions 2008).

Perioperative management of diabetes mellitus

With approximately 25% of all hospital inpatients having diabetes, rates of those subject to surgery are also inevitably rising. A proportion of these surgical procedures is as a direct result of diabetic complications (Patel 2008). Any surgical procedure will elicit a stress response in the patient to increase the circulating blood glucose levels by the mechanisms previously described. This glucose is a necessary energy source for tissues. However, in patients with diabetes mellitus, this response is not as effective due to insulin resistance or deficiency, and increased glycogenolysis and gluconeogenesis lead to hyperglycaemia. Insulin administration may be required to counteract this rise in blood glucose levels in order to achieve a normoglycaemic state (Dagogo-Jack & Alberti 2002).

The management of patients with diabetes in the surgical setting requires a customised, personalised approach for each individual, taking into account his or her blood glucose control, history and examination findings, as well as expected insulin requirement pre-and perioperatively. In the elective setting, the first step in perioperative management of diabetes mellitus is a thorough preoperative assessment. Not only are blood glucose levels or glycated haemoglobin (Hb1Ac) assessed here, but a complete history and examination are carried out. Appropriate investigations for cardiac, renal and peripheral nerve function should be carried out to give an accurate assessment of the patient's preoperative diabetic state (Marks 2003). If a patient is newly diagnosed as having diabetes mellitus preoperatively or his or her current blood glucose control is poor, surgery should be delayed where possible until appropriate control has been attained.

When planning for theatre lists, it is preferable to have patients with diabetes placed in the earliest available slots to reduce the patient fasting time (Hoogwerf 2006). The WHO Surgical Safety Checklist, which has been rolled out nationwide, provides a basic framework of surgical safety standards that can be applied globally to try to decrease the number of surgical deaths and complications. This is particularly relevant in the context of elevated risk of surgical site infections in patients with diabetes. Control of hyperglycaemia and administration of prophylactic antibiotics where appropriate, will minimise the favourability of bacterial colonisation at the surgical site (WHO 2008). Both intra-and postoperatively, particularly in patients with reduced mobility and peripheral sensation loss due to diabetes, heel protectors may be applied to prevent ulcerations secondary to pressure (Hoogwerf 2006).

Perioperative management of patients on oral medication for diabetes mellitus

Patients on oral medication for the control of diabetes mellitus are advised to stop their medication on the day of surgery, due to the risk of hypoglycaemia as well as the associated risk of lactic acidosis with metformin use (Dagogo-Jack & Alberti 2002).

If the blood glucose levels are poorly controlled, or if the patient is undergoing major surgical procedures, insulin intravenous infusion should be commenced with regular monitoring of blood glucose levels (Marks 2003). Any oral medication, apart from metformin, should be recommenced with the patient's first meal postoperatively. In the case of metformin, it can be restarted once renal impairment has been ruled out in the patient, due to the risk of associated lactic acidosis. If it is not safe to recommence metformin use and the blood glucose levels are rising, it is appropriate to discuss alternative management with an endocrinologist (Dagogo-Jack & Alberti 2002).

Perioperative management of patients on insulin for diabetes mellitus

In patients who use subcutaneous insulin to manage their diabetes mellitus, the insulin should be stopped on the day of surgery and an intravenous insulin infusion administered preoperatively with regular blood glucose monitoring (Table 1). The sliding scale illustrated in Table 1 is only an example and the choice of insulin infusion utilised perioperatively will depend on local NHS trust protocols, developed in collaboration with endocrinologists and anaesthetists. Potassium monitoring is important, because insulin stimulates cellular uptake of potassium, whereas hyperosmolarity can cause loss of potassium into the extracellular space and acidosis can cause hyperkalaemia. In a typical protocol, patients with normal renal function are given 20 mmol potassium/litre dextrose (Eldridge & Sear 1996). It is essential to ensure that no long-acting or subcutaneous insulin is given on the day of surgery, and if some is administered the surgeon and anaesthetist should be informed.

The key to good perioperative glycaemic control is to keep the patient's blood glucose level within a predetermined range to avoid sudden hyperglycaemia and hypoglycaemia. The American Diabetes Association suggests a target range of 90-126 mg/dl (4.95-6.93 mmol/l) in general surgical patients who are fasting. However, a target range of 120-180 mg/dl (6.6-9.9 mmol/l) has been suggested by Marks (2003) and Dagogo-Jack & Alberti (2002). There has been no determined standard target range in the literature, and as mentioned earlier the range depends on individual NHS trust protocols. For patients with type 1 diabetes, the infusion rate can be started at 0.5-1.0 unit/h, whereas

Insulin sliding scale infusion patients with type 2 diabetes taking an insulin infusion can be started at a rate of 1-2 units/h (Dagogo-Jack & Alberti 2002).

After surgery it is important to resume glucose maintenance via oral medication or insulin administration to prevent diabetic emergencies such as diabetic ketoacidosis or hyperosmolar non-ketotic coma. Early warning signs such as drowsiness, abdominal pain and breathlessness should be noted by any of the staff involved in the patient's care. Prompt recognition of these emergencies means that effective management can be started, potentially saving lives. Airway and accurate fluid resuscitation along with insulin and electrolyte administration play key roles in managing this situation without provoking fluid overload, or pulmonary or cerebral oedema (DH 2007). Close monitoring of patients with diabetes immediately after surgery, with complete observations and blood glucose levels every 1-2 hours, should also help to detect any worsening patient states (Rehman & Mohammed 2003).

Conclusion

With the worldwide prevalence of diabetes mellitus increasing and more people falling victim to its associated complications, it is likely that surgery on patients with diabetes will increase in the future. Good blood glucose control remains the key to optimisation of the patient's health and prevention of complications, but must be monitored together with all the other perioperative measures discussed. In taking this collective approach and addressing all issues simultaneously, one hopes that the management of diabetes can become associated with fewer complications.

Task 1

Project

Identify the Insulin Sliding Scale protocol used in your department and identify its similarities and differences compared with the protocol highlighted in Figure 1.

National Learning Hours

1 hour

Knowledge and Skills Dimension

Core 3: Health, Safety and Security

HWB7: Interventions and treatment

G1: Learning and development

Task 2

Discuss

What steps are taken during the preoperative, intraoperative and postoperative period to ensure optimal management of the patients' diabetes?

Notional Learning Hours

1 hour

Knowledge and Skills Dimension

Core 3: Health, Safety and Security

Core 4: Service improvement

Core 5: Quality

HWB2: Assessment and care planning to meet people's health and well-being needs

HWB7: Interventions and treatment

Task 3

Case study

A forty-year-old non-insulin-dependent diabetic patient undergoes an elective knee arthroscopy under general anaesthetic. He omits his hypoglycaemic medication on the morning of surgery as instructed. Following the procedure he starts experiencing anxiety, sweating, tremors, palpitations, nausea and weakness in recovery. What could have happened and what will you do?

Notional Learning Hours

30 mins

Knowledge and Skills Dimension

Core 2: Personal and people development

Core 3: Health, Safety and Security

HWB6: Assessment and treatment planning

HWB7: Interventions and treatment

Provenance and Peer review: Commissioned by the Editor; Peer reviewed; Accepted for publication June 2010.

References

Cameron CG, Bennett HA 2009 Cost-effectiveness of insulin analogues for diabetes mellitus Canadian Medical Association Journal 180(4) 400-7

Dagogo-Jack S, Alberti KGMM 2002 Management of Diabetes Mellitus in Surgical Patients Diabetes Spectrum 15 44-48

Department of Health 2007 National Service Framework for Diabetes: Standards Modern Standards and Service Models London: DH

Eldridge AJ, Sear JW 1996 Perioperative management of diabetic patients: any changes for the better since 1985? Anaesthesia 51(1) 45-51

Falanga V 2005 Wound healing and its impairment in the diabetic foot Lancet 366 1736-43

Gale EAM and Anderson JV 2002 Diabetes mellitus and other disorders of metabolism. In: Kumar P and Clark M, ed. Clinical Medicine. 5th ed. 10691104. WB Saunders, London, UK

Hirsch IB, McGill JB, Cryer PE et al. 1991 Perioperative management of surgical patients with diabetes mellitus Anaesthesiology 74(2) 346-359

Hoogwerf BJ 2006 Perioperative Management of diabetes mellitus: how should we act on the limited evidence? Cleveland Clinic Journal of Medicine 73 95-99

Marhoffer W, Stein M, Maeser E et al. 1992 Impairment of polymorphonuclear leukocyte function and metabolic control of diabetes Diabetes Care 15 256-260

Marks JB 2003 Perioperative Management of Diabetes American Family Physician 67 93-100

Marks JB, Skyler JS. 1996 Complications of diabetics: diabetic ketoacidosis and hyperosmolar hyperglycaemic nonketotic coma. In: Hurst JW, ed. Medicine for the practicing physician 4th ed. 639-643 Appleton and Lange, Connecticut, USA

National Collaborating Centre for Chronic Conditions 2008 Type 2 Diabetes London: Royal College of Physicians

National Collaborating Centre for Chronic Conditions 2010 Type 1 diabetes: diagnosis and management of type 1 diabetes in children, young people and adults London: NICE

Patel KL 2008 Impact of tight glucose control on postoperative infection rates and wound healing in cardiac surgery patients Journal Wound Ostomy Continence Nursing 35(4) 397-404

Rehman H, Mohammed K 2003 Perioperative management of Diabetic Patients Current Surgery 60(6) 607-611

Underwood JCE 2002 Diabetes Mellitus In: General and Systematic Pathology Churchill Livingstone, Sheffield, UK

Walker M, Marshall SM, Alberti KGMM 1989 Clinical aspects of diabetic ketoacidosis Diabetes / Metabolism Reviews 5 651-663

World Health Organization 2008 Guidelines for Safe Surgery Geneva, WHO

World Health Organization 2010 Diabetes Programme Available from http://www.who.int/diabetes/facts/world_figures/en/ [Accessed: 22 April 2010]

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About the authors

Baljinder S Dhinsa

MBBS

University College London Institute of Orthopaedic and Musculoskeletal Sciences, Royal National Orthopaedic Hospital, Stanmore, Middlesex

Wasim S Khan

MB ChB, MSc, MRCS, PhD

University College London Institute of Orthopaedic and Musculoskeletal Sciences, Royal National Orthopaedic Hospital, Stanmore, Middlesex

Ansuya Puri

BSc

University College London Medical School, London

No competing interests declared

Correspondence address: Mr WS Khan, Academic Clinical Fellow, University College London Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic

Hospital, Stanmore, Middlesex, HA7 4LP. Email wasimkhan@doctors.org.uk
Table 1

Insulin sliding scale infusion

50 units of Actrapid insulin in 50 ml of 0.9% saline
should be infused at a rate adjusted according to
the infusion table below.

Blood glucose (mmol/l)     Insulin infusion rate (ml/h)

0-4                             0.5 (call doctor)
4.1-7.0                                 1
7.1-11.0                                2
11.1-15.0                               3
15.1-20.0                               4
>20                              6 (call doctor)
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Article Details
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Title Annotation:OPEN LEARNING ZONE
Author:Dhinsa, Baljinder S.; Khan, Wasim S.; Puri, Ansuya
Publication:Journal of Perioperative Practice
Article Type:Report
Geographic Code:4EUUK
Date:Oct 1, 2010
Words:2909
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