Hypertension &

DiabetesIn surgery.

Presented by: Dr. Saifuddin Ahmed.

Dr. Sammya Das Gupta.

Surgery with Hypertension

What is HYPERTENSION Hypertension is defined as a rise in blood pressure over and above the normal range for the age of a patient for three consecutive setting.

Types: According to cause

ESSENTIAL

SECONDARY

NE release (stress)Thickened arterial wall Altered vasomotor Endocrine,

Renal, ICP, coarctation

, contracep-

tives, pregnancy,

etc.

Category Systolic mmHg Diastolic mmHg

Optimal < 120 and < 75Normal < 130 and < 85Mild HTN 140-159 or 90-

99Moderate 160-179 or 100-109Severe > 180 or > 110Isolated SBP HTN > 140 and < 90Pulse Pressure > 65mmHg

Orthostatic changes Hyper response > 20 mmHg Hypo response < 20

mmHG

Classification

0

10

20

30

20 30 40 50 60 70 80 90Age

Prev

alen

ce %

Women

Men

Circulation 2006;114:2780-7

Risk increases with age; Prevalence is more in women

Hypertension in surgical patient

High blood pressure is discovered during routine physical examination for a surgical disorder.

Patient on medical treatment for essential hypertension may develop a surgical condition that requires treatment.

Surgical treatment is required for a disorder causing secondary hypertension.

Importance of hypertension in surgical patient:

Higher risk of coronary artery disease.

High fluctuations in blood pressure during surgery, often associated with myocardial ischemia.

These blood pressure fluctuations correlates with post operative cardiac morbidity.

Therefore, control of blood pressure preoperatively should help to reduce blood pressure fluctuations during surgery and perioperative myocardial ischemia.

This is the rationale behind ensuring that the resting BP is controlled prior to surgery.

Systolic Blood Pressure

Adverse events are higher with isolated systolic blood pressure HTN, than with diastolic blood pressure HTN

Kannel, Framingham Heart Study

Perioperative risks and their management

In hypertensive patients, induction of anaesthesia is often associated with large reductions in arterial pressure. This may precipitate myocardial ischaemia as the diastolic pressure falls thus reducing both the coronary and the cerebral perfusion pressures. In these circumstances vasopressors may be indicated.

Laryngoscopy and intubation often cause large increases in blood pressure. As hypertension associated with tachycardia can cause myocardial ischaemia, prevention of the hypertensive response to laryngoscopy, intubation, and extubation is advisable.

Consequences of pressure surges include bleeding from vascular suture lines, cerebrovascular haemorrhage, and myocardial ischaemia/infarction.

The mortality rate of such events may be as high as 50%.

Perioperative hypertensive crises are generally caused by a sympathetically mediated increase in peripheral vascular resistance. The choice of the most appropriate antihypertensive therapy depends upon the clinical scenario, i.e. whether there is tachycardia, myocardial ischaemia, cardiac failure, or renal functional impairment.

Clinical assessment of preoperative hypertension:

It is desirable that the hypertensive patient undergoes full cl inical assessment prior to surgery. This should focus on three issues.

First, careful review of whether existing medications, if they are controll ing the blood pressure and when necessary, additional therapy is instituted.

Second, target organ (Heart, Kidney) damage. Any target organ damage increases the operative risks.

Third, to exclude rare secondary causes of hypertension, e.g. PhaeochromocytomaAbdominal bruit [Renal artery stenosis]Hypokalaemia [Conn’s syndrome]Radiofemoral delay [Coarctation of Aorta]

Preoperative Management of hypertension

Anti hypertensive medication should be continued throughout the perioperative period in order to maintain control of blood pressure and prevent rebound hypertension.

If blood pressure needs to be controlled more before surgery, then, some manipulation of the patient’s oral therapy can normally be undertaken with a successful result in a few days and hence, surgery does not need to be delayed unduly.

If surgery is required more urgently, rapidly acting agents specially beta blockers can be used to control blood pressure in a few minutes or hours.

Untreated & sub optimally treated hypertension do not appear to significantly increase risk when the pressure is below 160/ 105 mmHg since it is relatively easy to reduce it with anaesthesia and parenteral agents. When the pressure exceeds 180/ 110 mmHg, the incidence of perioperative HTN increases along with the need for prolonged parenteral treatment & observation as well as the risk of complication.

List of anti hypertensive drugs:

The five classes of drugs commonly used are:

Thiazide diuretics, Beta blockers, Ca Antagonists, ACE inhibitors. Angiotensin-II receptor antagonists.

If a new anti hypertensive is introduced, a stabilization period of at least 2 weeks should be allowed.

Bailey & Love 26th ed. ch 16, page 232.

Causes of postoperative hypertension Post operative acute retention of

urine Pain Hypothermia Peri operative Volume overload Hypercarbia & hypoxia Post operative Hyper adrenergic

state

Surgery with Diabetes

Normal Diabetic

DiabetesDiabetes 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).

Diabetes and Surgery 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 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

Metabolic Responses to SurgeryHormonal

◦Secretion of stress hormones Cortisol Catecholamines Glucagon Growth Hormone Cytokines

◦Relative decrease in insulin secretion

◦Peripheral insulin resistance

Metabolic◦Increased

gluconeogenesis and glycogenolysis

◦Hyperglycaemia◦Lipolysis◦Protein

breakdown

Metabolic Response to Surgery with DiabetesHypoglycaemia Hyperglycaemia Ketoacidosis Electrolyte imbalance

Underlying Systemic Complications of Diabetes

and SurgeryCardiac:◦Ischaemic Heart Disease - Often silent

ischaemia ◦Coronary artery disease ◦HypertensionRenal: ◦Renal dysfunction◦Urinary infection

Underlying Systemic Complications of Diabetes

and SurgeryImmune 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

Determinents of the management plan1. Type of DM2. Treatment, diet, oral ant diabetic drugs,

insulin3. Previous H/O hypoglycemic or hyperglycemic

attack and hospital admissions. 4. Metabolic status5. Vascular status: cardiac, renal, cerebral6. Surgery: Type: emergency or elective Minor or major procedure Type of anesthesia Post operative oral intake 29

Pre-operative AssessmentThis is the most important step in the

management of the diabetic patient Involves a thorough history and physical

examination Review prior anaesthetic records to determine

whether there were any difficulties with intubation or anaesthetics

Lab investigations◦ blood glucose - K+◦ BUN - creatinine◦ ketones - proteinuria◦ HbA1c (to assess how well controlled diabetes

is)

Principle of Pre-operative management

Metabolic stress of surgery and anesthesia cause increased elaboration of catecholamins, glucocorticoids, glucagon, and growth hormone, all producing their metabolic effects resulting in hyperglycemia in the pre-operative period.

The glycemic control is aimed to achieve a fasting plasma glucose of < 140 mg % and post prandial plasma glucose of < 200 mg %.

Insulin dependent diabetic patients can be admitted 2-3 days prior to surgery to achieve satisfactory control.

31

Principle of Pre-operative management

In NIDDM patients if the control is good with oral antidiabetic drugs , these drugs are stopped on the day of the surgery and intravenous fluids and insulin are given , if not are advised to stop drugs one week before surgery and admitted for insulin therapy.

On the day of surgery, It is preferable to take diabetic patients for surgery in the morning as first case.

32

Surgical Management of Insulin Dependant Diabetes Mellitus

Aim to keep blood glucose 5 to10mmol/LPre operative

◦NBM for 6 hrs prior to surgery (4 hrs for clear fluids)

◦ Initiate glucose/ potassium/ insulin regime after commencing NBM (check K+ as well) 500ml 10% glucose solution with 20mmol

K+ 15 unit short acting insulin at 1ml.kg-1.hr.

◦Hourly capillary glucose is measured until operation

Surgical Management of Insulin Dependant Diabetes Mellitus

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

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

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 NBM for 12 hours prior to operationStart i.v maintenance fluid

◦ 0.18% NaCl with glucose 4%Hourly capillary glucose is measured until

operation

Surgical Management of Non Insulin Dependant Diabetes Mellitus

Hourly glucose monitoring◦Aim to keep within 5-10mmol/L◦if blood glucose >10 mmol/L, switch to

treating as insulin dependantPost-operative

◦Continue Glucose/Potassium/Insulin regime until patient can take orally.

◦Restart oral anti diabetic with first meal.

Summary: The hypertensive patient requires careful

pre operative assessment to make sure that blood pressure is controlled and to exclude secondary causes. These may require surgery to be delayed somewhat, but hypertension itself seldom causes anything more than a slight delay to surgery. If blood pressure needs to be controlled more before surgery, then, some manipulation of the patient’s oral therapy can normally be undertaken with a successful result in a few days and hence, surgery does not need to be delayed unduly.

Summary: Management of preoperative insulin

therapy depends on baseline blood glucose, level of diabetic control, severity of illness and the proposed surgical procedure

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

Refference: Essential Surgical Practice – A. Cuschieri. Short practice of Surgery - Bailey & Love. Current Surgical Diagnosis & Treatment – Gerard M.

Doherty. The surgical hypertensive patient - P Foëx, DPhil FRCA

FMedSci, Emeritus Nuffield Professor of Anaesthetics, Nuffield Department of Anaesthetics, The John Radcliffe Hospital, Headley Way, Oxford, PhD FRCA.

Perioperative management of hypertension - Norman M Kaplan, MD

Perioperative hypertension management - Joseph Varon and Paul E Marik.

T H A N K Y O U