Glycemic control in infected diabetic foot

1. Glycemic control in infected diabetic foot Dr Mala Dharmalingam MD, DM Endocrinologist and Diabetologist

2. It has been forced upon me that the diabetic gangrene is not heaven sent but earth born Elliot P Joslin

3. The Problem • Estimated life time risk of diabetic foot - 15% • Risk to undergo some degree of foot ulcerations 5-10% • Diabetics undergone amputation 1% • Major cause of amputation -50%

4. The Problem • 12.3% of patients given a foot examination • Average length of stay in hospital 26 days • $16,614 per admission excluding surgical charges • survival rates post amputation • 5yr 41% • 3yr 65%

5. Socioeconomic costs Direct & Indirect costs • Cost of surgery • lost employment opportunities & income • psychosocial impact

6. Mortality & Morbidity • Mortality • Myocardial infarction • Morbidity • septicemia • hypoglycemia • ketoacidosis

7. Aims of treatment • Avoid hypoglycemia, hyperglycemia, • Avoid lipolysis, ketogenesis, protein catabolism • Avoid electrolyte imbalance • carefully managed diabetes does not increase risk of complications

8. Factors involved in impairment of wound healing in a diabetic • Vascular insufficiency • Altered inflammatory responses • Fibrosis • Abnormalities in release of growth Factors • over expression of the proteases and oxygen free radicals • hypoxia • Delayed keratinocyte migration

9. Foot & Infection • Primary • Secondary • Presence of vasculopathy/neuropathy • abnormalities in defense mechanism of chemotaxis phagocytosis, intracellular bactericidal activity & sr opsonization

10. Causes of infection in diabetes • Alteration in leukocyte function • Decreased chemotaxis • impaired phagocytic activity of granulocytes • reduce intracellular killing of pneomococci and staphylococci • BG and ketones a good permissive milieu for development of infection • BG < 200-250 mg% restores all leukocyte dysfunction to normal

11. Metabolic effects of infection • Worsen glucose tolerance • gluconeogenesis is stimulated by increase in counter regulatory hormones • insulin resistance-particularly in the skeletal muscle, lesser extent in liver • increase in cytokines released by immune cells in response to infection • TNF, IL impair insulin action by inhibiting tyrosine kinase activity of the insulin receptor • require more insulin

12. Metabolic effects of infection • Elevation of glucagon levels • stimulates ketogenesis and the associated ketoacidosis and infection

13. Metabolic responses to surgery and effects of diabetes Surgery Trauma Wound infection Haemorrhage stress Increased counter regulatory activity Inc Symp. activity Insulin secretion inhibited Insulin sensitivity reduced Periop starvation Increased catabolic flux DM  Glycogenolysis  Proteolysis  Lipolysis gluconeogenesis  ketogenesis hyperglycemia protein loss ketosis

14. Why surgery in a diabetic is different • Lack of endogenous insulin • Elevated levels of counter regulatory hormones- (GH, glucagon, corticosteroids, catecholamines)- lead to protein breakdown

15. Is wound healing different in a diabetic • Abnormal cellular/inflammatory pathways • abn. in fibroblasts and neutrophils • Hyperglycemia toxic to cellular elements • greater susceptibility to infection • AGE accumulate and may adversely affect extracellular matrix production, cell function, and cytokine production- prevent wound healing • peripheral neuropathy

16. Is wound healing different in a diabetic • vascular disease/tissue hypoxia • gradient of oxygen tissue pressure is required for fibroblast growth and initiation of angiogenesis, chronic hypoxia impairs wound healing • defective hyperemic responses and endothelial dysfunction may also be important in pathogenesis of foot ulcers

17. Diabetic foot wound • Diabetic foot-ulcers, infections of the foot cellulitis, osteomyelitis • wound- acute/ chronic • wound unhealed for 4 weeks -bad prognosis- including amputation

18. Value of treating a diabetic foot wound • To control infection • infected wounds are minimally symptomatic displaying only drainage, odour and mild discomfort • progress to involve deeper soft tissues or bone • problem- limb/life threatening

19. Value of treating a diabetic foot wound • to improve function • improves appearance of foot • return to ambulation in appropriate footwear • to improve quality of life • relieves burden of changing dressing and applying medications • better able to negotiate activities of daily living • less of a burden to family/society

20. For whom will antibiotic therapy be beneficial • Patients with clinically uninfected lesion- non inflamed neuropathic ulcer • non limb threatening infections • limb threatening infections • Osteomyelitis

21. Management of infection • Diagnosis of infection of a chronic wound is based on clinical rather than microbiological criteria. • Presence of pus or presence of two or more signs of inflammation- (erythema, warmth, tenderness, heat, induration)

22. Non inflamed neuropathic ulcer • Foot infections may be associated with few or no local or systemic signs or symptoms • Frequent follow up and communication • ?? antibiotic

23. Non Limb Threatening infections • Antibiotic -initiated promptly • mild-moderate- oral agent except in pts with GI absorption problems/allergic/resistant to oral drugs • oral antibiotics - cephelexin, clindamycin,amoxicillin/clavularate. Newer fluoroquinones-trovafloxacin-polymicrobial infections

24. Non Limb Threatening infections • Outpatient basis • urgent surgical intervention, multiple diagnostic tests, immunocompromised -admit • outpatient should be seen every 72 hours • review after culture report is available

25. Limb threatening infections • Hospitalised • deep wound and blood cultures • broad spectrum antibiotic therapy • imipenam/cilastin, vincamycin+aztreonam+MNZ • Fluid and electrolyte balance

26. Osteomyelitis • Prolonged antibiotic therapy > 6 weeks-week or two of parenteral therapy • Infected bone which can easily resected should be without compromise to long term foot function

27. Why good BG control is essential • There is insulin deficiency, unopposed catabolism and hyperglycemia • increased perioperative mortality • ketosis and acidemia • osmotic diuresis leading to electrolyte imbalance and volume depletion • hyperglycemia exacerbates ischemic brain damage through increased glycolysis intracellularly

28. Why good BG control is essential • Impaired wound healing • hyperglycemia interferes with leukocyte chemotaxis, opsonisation and phagocytosis leading to a high risk for bacterial and fungal infection

29. Goals of treatment • To maintain health status • foot infections can impose an increased metabolic demand on the patient by worsening glycemic control, renal and cardiac functions • impairing nutritional balance or other metabolic parameters • impairing mobility- general deconditioning and psychosocial dysfunction

30. Goals of treatment • Goal - prevent wounds from becoming infected • treating infections- bacterial resistance • burdens patient with antibiotics- allergic reactions, trouble some side effects.

31. Goals of treatment • Prevent amputations • physical and emotional toll on the patient • one amputation perpetuates the need for another • To reduce costs • Treating an ulcer less expensive than amputation

32. Preoperative recommendations • Patients on OHA - Well controlled • Continue • Patients on OHA requiring insulin • infection • non healing ulcer • hyperglycemia • inability to take oral medications

33. Preoperative recommendations • Pts on chlorpropamide stop at least 5 days before surgery • long acting SU avoid • Metformin discontinued at least 48 hr prior to and 48 hr subsequent to procedure- reinstitute only after renal function reevaluated

34. Preoperative recommendations • Metformin- hyperlactemia & renal function may deteriorate during anesthesia. • increases risk of potential hypotension and anaerobic metabolism. • All SU stopped in the morning of the surgery and withheld till patient resumes eating.

35. Why insulin • Insulin resistance • electrolyte homeostasis • which insulin ??

36. Type 2 diabetics on insulin • If patient is well controlled continue same insulin regimen • Newly diagnosed-purified insulins to prevent antibody formation

37. Type 2 diabetics on insulin • If patient is well controlled continue same insulin regimen • Newly diagnosed-purified insulins to prevent antibody formation

38. Type 2 diabetics on insulin • If patient is well controlled continue same insulin regimen • Newly diagnosed-purified insulins to prevent antibody formation

39. GIK regimen • GIK 1-10% glucose 10 mmol KCl +10 units of insulin • GIK 2-10% glucose 10 mmol KCl +15 units of insulin • GIK3-10% glucose 10 mmol KCl +20 units of insulin

40. 2 separate lines if fluid overload • Insulin infusion pump- • Portable insulin infusion pumps • advantages of portable pump- wide range & flexibility of dose • even used in the postoperative period & cut short hospital stay • Disadvantage- high cost, lack of trained personnel, technician for repair and servicing of pump • Bigger injection insulin infusion pumps

41. Moderate control • Prevent ketoacidosis, hypoglycemia • Nil by mouth after midnight • on day of surgery- 1/2 morning dose s/c and start 5% dextrose at 125ml/hr/70kg • monitor plasma glucose every 1-2 hr • Blood Glucose to be maintained around 150-200mg/dl

42. Disadvantages with Subcutaneous insulin • Insulin is poorly absorbed from the peripheral sites in the presence of hypotension due either to anaesthesia or to complications of surgery itself • Insulin absorption is not constant, it rises to a flattened peak in serum and declines over many hours • Absorption is erratic, changes with temperature and drops with fall of cardiac output

43. Disadvantages with IV bolus • Unphysiologic • Depending on initial plasma glucose levels, patients given IV insulin injection may manifest very high insulin concentrations which may cause hypoglycemia • This results in greater lipolysis and ketogenesis resulting in electrolyte imbalance and predisposing to cardiac arrhythmia

44. Advantages of continuous IV infusion • Induces near physiological metabolic state better than with other routes • Any variation in the rate of flow of the infusion, insulin and glucose can be modified • More flexible

45. Adjunctive therapy • Glycemic control • adequate insulin • Trt. of co morbid conditions • medical nutrition therapy

46. Adequate diabetic control • Adequate glycemic control can prevent late complications • Good long term control - SHBGM • HbA1C • Inadequate control- tissue damage • Sorbitol accumulation • changes in myoinositol metabolism- alteration in polyphosphoinositide signalling pathway

47. Medical Nutrition Therapy in the perioperative period • Energy requirement - basal energy (women) expenditure =65.1+(9.5 x wt)+(1.85x ht)- (4.68 x age) • BEE (men)+ 66.47+(13.75xwt)+(5xht)-(6.76 x age) • Total energy requirement (TER) =BEE x Stress Factor(SF) • SF for surgery=1.5

48. MNT in the perioperative • Protein requirement 1.5-2.5 g/kg body weight • Fat allowance- 30g- 75g/day

49. Conclusion in MNT • A balanced diet that ensures a good intake of minerals and vitamins. • Small frequent nutritious feeds .

50. Conclusion • Prevention of macroangiopathic complications of diabetes assumes importance in India in the face of the growing numbers • Good glycemic control & adequate foot care can go a long way in preventing foot ulcers