Demonstrate knowledge of basic pre-operative and post-operative care.

Basic Pre-Op and Post-Op Care

Clinical Overview

Start with one idea and build everything from it: a surgical operation is a controlled injury, and the body responds to a controlled injury exactly as it responds to any injury. A scalpel divides tissue, vessels bleed, cells die, bacteria are introduced, and the patient is frightened, fasted and immobile. The body answers with a stereotyped programme — inflammation, a neuroendocrine stress response, a shift toward clotting, and a slow repair of the wound. Good perioperative care is simply knowing that programme well enough to keep its useful parts and blunt its dangerous parts.

From that single principle the whole chapter follows. If surgery is a controlled injury, then before theatre we ask whether the patient has the reserve to survive an injury of this size, fix what we can while there is time, and obtain genuine consent for the injury we are about to do. During theatre we keep the injury as small as possible and stop predictable harm before it happens. After theatre we watch for the injury's complications — bleeding, infection, clot, the metabolic and gut consequences of stress, and the failure of the wound itself — and we catch them early because the body warns before it crashes.

So the foundation is mechanism: what can surgery do to physiology, what can physiology do to surgery, and what recurring checks make a patient safer? The operation is only the middle event; the reserve estimate beforehand and the structured surveillance afterwards do most of the work of keeping a patient alive.

High-yield chains:

Tissue injury + anxiety + fasting + pain -> sympathetic/HPA activation -> insulin resistance, catabolism, sodium retention and hypercoagulability -> ERAS aims to blunt this stress response.

Pelvic surgery + immobility + malignancy/pregnancy -> stasis, endothelial injury and hypercoagulability -> VTE risk -> mechanical and pharmacological prophylaxis chosen by risk and bleeding balance.

Skin incision + bacterial inoculum + tissue injury -> surgical-site infection risk -> antibiotic tissue levels must be adequate at incision.

Fasting + blood loss + third-space shifts + vasodilatation -> changing effective circulating volume -> fluid therapy must target perfusion without overload.

Opioids + gut handling + electrolyte disturbance + immobility -> ileus, nausea, retention and delayed mobilisation -> multimodal analgesia and early recovery principles matter.

Core Knowledge

The Body's Response to Surgical Injury

Before any of the clinical decisions make sense, anchor on the biology they are built around. Cutting tissue triggers three overlapping programmes: a local inflammatory response at the wound, a whole-body neuroendocrine stress response, and the repair process that eventually heals the wound. Each is normal and protective. Each can also become a complication.

Local inflammation is the immediate, stereotyped tissue reaction to injury, and it produces the five features the reader already knows from any infected or injured area: redness, heat, swelling, pain and loss of function. The mechanism behind them is worth holding onto because it explains both healing and the warning signs the team watches for afterwards. Injured cells and mast cells release mediators — histamine, prostaglandins, leukotrienes, bradykinin, complement fragments and cytokines such as the interleukins and tumour necrosis factor. These cause local vasodilatation (giving redness and heat from increased blood flow) and increased capillary permeability (letting protein-rich fluid leak into the tissue, giving swelling), while other mediators recruit white cells and sensitise nerve endings (giving pain and loss of function). The first responder cell is the neutrophil, which dominates the early hours; the macrophage arrives later to clear debris and orchestrate repair. This is useful at a clean wound. The same physiology, amplified and spread by infection, is the early language of sepsis — which is why a postoperative patient who becomes warm, tachycardic and tender is showing inflammation that may have escaped local control.

Wound healing is how the injury is repaired, and the route depends on how the edges sit. When the edges are clean and closely apposed — a sutured laparotomy or a port site — healing is by first (primary) intention: a thin clot bridges the gap, epidermis migrates across it within days, and new vessels and fibroblasts lay down a small amount of granulation tissue that is later remodelled into a fine scar. When tissue is lost or the wound is left open — a dehisced or infected wound packed to heal from the base — healing is by second (secondary) intention: far more granulation tissue forms, myofibroblasts contract the wound inward, and the defect is filled and re-epithelialised slowly with a larger scar. Three messenger molecules drive much of this repair, and they are worth naming because they explain why healing fails in sick patients: transforming growth factor beta and epidermal growth factor stimulate fibroblast and epithelial proliferation, and adequate oxygen and protein delivery are required for collagen to be laid down and cross-linked.

That last point is the bridge to the whole chapter. Wound healing is only as good as its substrate. Anything that starves the wound of oxygen, building blocks or clean conditions impairs it:

When healing fails, it fails in two directions: inadequate union (wound breakdown, or dehiscence, where layers separate) or excessive scarring (hypertrophic scar and keloid, where repair overshoots). Fetal tissue, by contrast, heals rapidly and almost without scar — a reminder that the scarring response is a property of the tissue and its environment, not an inevitable law.

The neuroendocrine stress response is the whole-body half of the injury programme, and it is built on later in this chapter under ERAS. In one line now: pain, tissue damage, fasting and fear drive catecholamines and cortisol up, which makes the patient insulin-resistant and catabolic — blood glucose rises, protein and fat are broken down for fuel, and sodium and water are retained. A starved, stressed patient mobilises fat to ketones for energy, which is why prolonged perioperative fasting is not harmless. This response evolved to keep an injured animal alive; in a planned operation much of it is unnecessary cost, which is exactly what enhanced-recovery care tries to minimise.