Describe Anaesthesia in Common Coexisting Diseases in detail.

Principle

Patients frequently have co-existing medical disease that increases anaesthetic risk. The principle is to assess control, optimise before elective surgery, continue key medication, and plan an anaesthetic that minimises the stress on the affected system. A selection of common conditions illustrates the approach.

Cardiovascular Disease

Hypertension should be reasonably controlled before elective surgery to avoid exaggerated swings in blood pressure; most agents are continued. In ischaemic heart disease, elective surgery is deferred after a recent myocardial infarction, anti-anginal therapy is continued, and anaesthesia is conducted to maintain the balance of myocardial oxygen supply and demand (avoiding tachycardia, hypotension and hypertension).

Diabetes & Respiratory Disease

Diabetes: assess control (HbA1c) and end-organ disease; adjust insulin/oral hypoglycaemics for the fasting period, place the patient first on the operating list, and monitor blood glucose closely (a glucose–insulin–potassium or variable-rate insulin regimen for major surgery). Asthma/COPD: optimise and continue inhalers/steroids, avoid triggers of bronchospasm, and favour regional techniques where suitable.

A General Framework for Any Coexisting Disease

Faced with any chronic condition, the same framework applies: assess how severe and how well controlled the disease is and whether it has caused end-organ damage; optimise what can reasonably be improved before elective surgery; decide which medications to continue, adjust or withhold; anticipate how the disease and its drugs will interact with anaesthesia; and plan monitoring and postoperative care accordingly, involving relevant specialists and critical care where needed. This structured approach matters because the perioperative period imposes major physiological stress, and it is the interaction between that stress, the disease and the anaesthetic that determines outcome.

Steroids & Other Special Cases

A few specific situations recur in exams: patients on long-term corticosteroids may have a suppressed hypothalamic–pituitary–adrenal axis and need perioperative steroid supplementation to cover the stress of surgery and avoid an Addisonian crisis; patients with thyroid disease should be rendered euthyroid before elective surgery; and those on anticoagulants and antiplatelet agents require a careful plan that weighs the thrombotic reason for the drug against the bleeding risk of surgery and any planned regional technique. Recognising these special cases and planning for them in advance prevents avoidable perioperative crises.

Elective surgery is deferred until comorbidity is optimised.

• Assess control, optimise before elective surgery, continue key drugs, plan to protect the affected system.
• Hypertension: control BP, continue agents, avoid swings; IHD: defer after recent MI, balance O₂ supply/demand.
• Diabetes: adjust insulin/OHAs, first on list, monitor glucose.
• Asthma/COPD: continue inhalers/steroids, avoid triggers, favour regional.
• Weigh risk–benefit for elective surgery; don’t delay emergencies for optimisation that can run concurrently.