Download Diabetes: perioperative management

Management of
Diabetes in Surgery
Diabetes
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Diabetes is a metabolic disorder resulting
from insulin deficiency or intolerance
Associated with acute and long term systemic
problems
Diagnosed by a random plasma glucose
>11.1mmol/l and a fasting glucose>7.0mmol/l
(WHO criteria)
The two most common forms of diabetes are
Insulin Dependant Diabetes Mellitus (Type 1)
and Non Insulin Dependant Diabetes Mellitus
(Type 2)
Type 1 Diabetes Mellitus
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Polygenic disorder thought to be of auto immune
aetiology
Results in destruction of β cells in the Islets of
Langerhans in the Pancreas, with subsequent insulin
deficiency
Young onset
0.4% prevalence
Endogenous insulin is required to maintain plasma
glucose levels to within physiological levels
Type 2 Diabetes Mellitus
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Hypoglycaemia resulting from reduced insulin
secretion and peripheral insulin resistance
Some genetic concordance
Older onset, associated with central obesity
Depending on severity, may be controlled
with:
– diet and exercise to lose weight
– oral hypoglycaemics
– insulin
Diabetes and Surgery
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Surgery is a form of physical trauma
It results in catabolism, increased metabolic rate,
increased fat and protein breakdown, glucose intolerance
and starvation.
In a diabetic patient, the pre existing metabolic
disturbances are exacerbated by surgery
The type of diabetes, amount of insulin dose, diet or oral
hypoglycaemic agents must be considered as this will
change the overall management plan
The risk of significant end-organ damage increases with
the duration of diabetes, although the quality of glucose
control is more important than the absolute time
Factors Adversely Affecting
Diabetic Control Perioperatively
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Anxiety
Starvation
Anaesthetic drugs
Infection
Metabolic response to trauma
Diseases underlying need for surgery
Other drugs e.g. steroids
Metabolic Responses to Surgery
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Hormonal
– Secretion of stress
hormones
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Cortisol
Catecholamines
Glucagon
Growth Hormone
Cytokines
– Relative decrease in
insulin secretion
– Peripheral insulin
resistance
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Metabolic
– Increased
gluconeogenesis
and glycogenolysis
– Hyperglycaemia
– Lipolysis
– Protein breakdown
Metabolic Response to Surgery
and Diabetes
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Hypoglycaemia
– May develop perioperatively due to the residual effects of
preoperative long acting oral hypoglycaemic agents or
insulin.
– Exacerbated by preoperative fast or insufficient glucose
administration
– Counter-regulatory mechanisms may be defective because
of autonomic dysfunction
– Can lead to irreversible neurological deficits
– Dangerous in anaesthetised or neuropathic patient as the
warning signs may be absent
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Management
– Give i.v dextrose and monitor glucose levels
Metabolic Response to Surgery
and Diabetes
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Hyperglycaemia
– Glucagon, cortisol and adrenaline secretion as part of the
neuroendocrine response to trauma, combined with
iatrogenic insulin deficiency or glucose overadministration
may result in hyperglycaemia
– Causes osmotic diuresis, making volume status difficult to
determine and risking profound dehydration and organ
hypoperfusion, and increased risk of UTI
– osmotic diuresis, delayed wound healing, exacerbation of
brain, spinal cord and renal damage by ischaemia
– Results in hyperosmolality with hyperviscocity,
thrombogenesis and cerebral oedema
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Management
– Frequently measure blood glucose and administer insulin
Metabolic Response to Surgery
and Diabetes
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Ketoacidosis
– Any patient who is in a severe catabolic state and has an
insulin deficiency (absolute or relative) can decompensate
into keto-acidosis
– Most common in type 1 patients
– Increased risk postoperatively, often precipitated by the
stress response, infection, MI, failure to continue insulin
therapy.
– characterised by hyperglycaemia, hyperosmolarity,
dehydration (may lead to shock and hypotension) and
excess ketone body production resulting in an anion gap
metabolic acidosis.
Metabolic Response to Surgery
and Diabetes
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Management
– restore intravascular volume
– eliminate ketonaemia
– control blood glucose
– replace electrolytes
– monitor glucose and ketone levels
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Mortality from DKA –5-10%
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Electrolyte abnormalities
– Anticipate imbalances in potassium, magnesium and
phosphate
Underlying Cardiac Complications
of Diabetes and Surgery
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Cardiovascular problems frequently present in long standing
diabetics
– Ischaemic Heart Disease - Often silent ischaemia
– Coronary artery disease
– Hypertension
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Diabetic patients must be considered as being at high risk of MI
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Silent MI in autonomic neuropathy as Cardiac Autonomic
Neuropathy may abolish the hearts response to stress
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Induction of anaesthesia and tracheal intubation can lead to a
reduction in cardiac output
Underlying Cardiac Complications
of Diabetes and Surgery
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Management
– Most cardiac and antihypertensive drugs should
be continued throughout the perioperative period
except, aspirin, diuretics and anticoagulants
– History to determine effort tolerance, clinical
examination for cardiac failure and an
electrocardiogram in all patients.
– Echocardiography can help in assessing an
ejection fraction in borderline cases
Underlying Renal Complications of
Diabetes and Surgery
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Renal
– Renal dysfunction
• Intrinsic renal disease including glomerulosclerosis and renal
papillary necrosis enhance the risk of acute renal failure
perioperatively
• Proteinuria is an early manifestation
• Dialysis should optimally be done the day before surgery.
– Urinary infection
– Management
• Urea and electrolyte determination.
• Dipstix urinalysis for proteinuria
Underlying Nervous System
Complications of Diabetes and
Surgery
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Nervous System
– Counter-regulatory response to hypoglycaemia
– Peripheral glove and stocking neuropathy with an
increased susceptibility to iatrogenic nerve injuries
– Cardiac Autonomic Neuropathy
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Management
– History of postural dizziness, post gustatory
sweating, nocturnal diarrhoea and impotence.
– Careful documentation of peripheral sensation
Underlying Orthopaedic
Complications of Diabetes and
Surgery
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Small Joint Disease
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Non-enzymatic glycosylation causing abnormal cross-linking of
collagen may lead to joint rigidity
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At the atlanto-occipital joint, it may result in difficult intubation
The small joints of the fingers and hands are also affected
– failure to approximate the palmar surfaces of the
interphalangeal joints are indicators of a difficult
laryngoscopy (positive prayer sign)
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Management
– Clinical assessment of neck extension, examination of the
small joints of the hand and a good evaluation of the ease of
intubation
Underlying Immune Complications
of Diabetes and Surgery
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Immune and infectious risk
– Diabetics are susceptible to infection and have delayed wound
healing
– Hyperglycaemia
• facilitates proliferation of bacteria and fungi
• depresses the immune system management
– Proteolysis and decreased amino acid transport retards wound
healing.
– Loss of phagocytic function increases the risks of post-operative
infection
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Management
– Need very strict sterile techniques and need to assess risk/benefit
ratio for procedures e.g catheterisation
Underlying Gastrointestinal and
Opthamological Complications of
Diabetes and Surgery
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Gastrointestinal
– Gastroparesis
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Management
– History of early satiety and reflux
– H2 blocker and metoclopramide
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Ophthalmology
– Cataracts, glaucoma and retinopathy decrease visual acuity
and increase the unpleasantness of the perioperative period
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Management
– Increase the amount of explanation and reassurance to the
patient.
Principles of Managing Diabetics
During Surgery
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Management of preoperative insulin therapy depends
on baseline blood glucose, level of diabetic control,
severity of illness and the proposed surgical
procedure
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However, aims for all diabetic patients are:
– No excess mortality
– No increase in post-op complications
– Normal wound healing
– No increase in duration of hospitalisation
– No hypoglycaemia, hyperglycaemia or
ketoacidosis
Pre-operative Assessment
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This is the most important step in the management of
the diabetic patient
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Involves a thorough history and physical examination
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Review prior anaesthetic records to determine
whether there were any difficulties with intubation or
anaesthetics
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Lab investigations
– blood glucose
- K+
– BUN
- creatinine
– ketones
- proteinuria
– HbA1c (to assess how well controlled diabetes is)
Pre-Operative Management
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Admit as early as possible prior to surgery
Avoid long-acting glucose lowering agents
– chlorpropamide
–glibenclamide
– ultralente insulins
Avoid metformin
Closely monitor blood glucose levels
– 2 hourly for Type 1
– 4 hourly for type 2
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Test urine every 8 hours for ketones
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Place first on morning operating list if possible
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Aim for a blood glucose of 5-10mmol/L
Surgical Management of Insulin
Dependant Diabetes Mellitus
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Aim to keep blood glucose 5 to10mmol/L
Pre operative
– NBM for 6 hrs prior to surgery (4 hrs for clear fluids)
– Anti aspiration prophylaxis
– Initiate glucose/ potassium/ insulin regime after commencing
NBM (check K+ as well)
• 500ml 10% glucose solution with 20mmol K+ at 1ml.kg1.hr-1 connected to Y piece with insulin syringe
• Make up insulin syringe as 50 units insulin in 50 ml saline
in a 50 ml syringe pump and run through Y piece with
10% glucose at between 1 to 5 u hr-1 (1 – 5 ml).
• Base on existing insulin regime
• Use sliding scale e.g. 1 u hr-1 if BG between 5 to 10
– Hourly capillary glucose is measured until operation
Surgical Management of Insulin
Dependant Diabetes Mellitus
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Intra-operative
– Hourly glucose monitoring
• keep between 5-10 mmol/L
– Two hourly potassium monitoring
• keep between 3.5-4.5 mmol/L
– Anaesthesia determined by patient
physiology and surgical requirements
– Set up additional IV for resuscitation fluids
Surgical Management of Insulin
Dependant Diabetes Mellitus
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Post-operative
– Continue Glucose/Potassium/Insulin
regime until patient can take orally
– Oral medication with first meal
– Allow for pain resulting in increased insulin
requirements
Surgical Management of Non Insulin
Dependant Diabetes Mellitus
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Treat as insulin dependant if:
– poorly controlled (blood glucose >10 mmo/L)
– major surgery
Pre-operative
– Biguanides must be stopped 48 hours before hand for fear of
lactic acidosis
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NBM for 12 hours prior to operation
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Start i.v maintenance fluid
– 0.18% NaCl with glucose 4%
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Hourly capillary glucose is measured until operation
Surgical Management of Non Insulin
Dependant Diabetes Mellitus
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Hourly glucose monitoring
– Aim to keep within 5-10mmol/L
– if blood glucose >10 mmol/L, switch to
treating as insulin dependant
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Post-operative
– Restart oral hypoglycaemics with first meal
Other Considerations with
Anaesthesia in Diabetic Patients
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Usual intra-operative monitoring
– record BP and pulse every 5 minutes
– watch skin colour and temp
• suspect hypoglycaemia if patient is cold and sweaty
– give IV glucose
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No contraindications to standard anaesthetic induction or
inhalational agents
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If the patient is dehydrated then hypotension will occur and i.v.
fluids will be needed
Conclusion
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The diabetic patient presents numerous
challenges to management during surgery
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Awareness of the complications should
enable tight metabolic control
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Correct management of the diabetic
patient during surgery reduces morbidity
and length of admission, as well as
resulting in better wound healing