Learn — Perioperative nursing

11 notes · 46 questions on the topic

Surgical safety checklist (WHO)

The WHO Surgical Safety Checklist is a 19-item verbal checklist run in three phases around every operation: Sign In before the induction of anaesthesia, Time Out before the skin incision, and Sign Out before the patient leaves the operating room. It matters because it is the cheapest life-saving intervention in surgery — in the original eight-country study it cut inpatient death from 1.5% to 0.8% and major complications from 11% to 7% — and it works by forcing the whole team to speak aloud, not by adding another form to the file.

Sign In is done before the induction of anaesthesia with at least the anaesthetist and the nurse present, and confirms identity, site, procedure and signed consent, that the site is marked, that the anaesthesia machine and drug check is complete, that the pulse oximeter is on and working, any known allergy, any difficult airway or aspiration risk, and whether more than 500 mL of blood loss (7 mL/kg in a child) is expected so that access and fluids are ready.
Time Out is called immediately before the skin incision with every member of the team stopped and listening: all introduce themselves by name and role, the surgeon, anaesthetist and nurse confirm the patient, site and procedure out loud, the surgeon states the critical steps, expected duration and anticipated blood loss, the anaesthetist states patient-specific concerns, the scrub nurse confirms sterility and the indicator result, and the team confirms that prophylactic antibiotic was given in the last 60 minutes and that essential imaging is displayed.
Sign Out is completed before the patient leaves the operating room, read aloud by the circulating nurse: the name of the procedure actually performed, that the instrument, sponge and needle counts are correct, that any specimen is labelled with the patient name read back from the container, whether there were equipment problems, and the key concerns of the surgeon, anaesthetist and nurse for recovery.
Antibiotic prophylaxis is a single intravenous dose timed so that the incision is made within 60 minutes of the infusion — cefazolin 2 g is the usual agent (3 g above 120 kg), vancomycin and fluoroquinolones are begun within 120 minutes because they must run slowly, and a repeat dose follows about 4 hours of operating or a blood loss over 1500 mL.
The operating surgeon marks the site with an unambiguous mark at or next to the planned incision, with the patient awake and involved, whenever there is laterality, multiple structures such as fingers and toes, or multiple levels as in spine surgery; the mark must still be visible after prepping and draping.
Sponge, instrument and needle counts are performed by the scrub and circulating nurse together at four points — before the operation begins, when a cavity is closed, when closure of the wound begins, and at skin closure; a count that does not reconcile means the wound is not closed until the field, drapes, floor and bins have been searched and, if needed, an intraoperative radiograph taken.
Wrong-site, wrong-procedure and wrong-patient surgery and a retained foreign object are never events, and almost always follow a failure to speak up; NABH accreditation standards require a documented safe-surgery checklist for every operation performed in an accredited Indian hospital.
The checklist is a team conversation and not paperwork: one nominated person (usually the circulating nurse) reads each item aloud and waits for a spoken answer from the named person, and the phase is not signed until every item has been answered.

Patient positions — surgical

Surgical positioning is the placement and support of the anaesthetised patient on the operating table so that the surgeon has access while the airway, circulation, nerves, joints and skin are protected. It matters because anaesthesia abolishes pain, muscle tone and the protective reflexes that normally make a person shift, so an injury that would take seconds to notice while awake goes unnoticed for hours — positioning nerve injury and pressure injury are among the commonest avoidable intraoperative harms, and the position is the nurse's responsibility shared with the anaesthetist.

Supine (dorsal recumbent) is used for most abdominal, thoracic, vascular and breast surgery; the arms are kept abducted no more than 90 degrees on padded boards with the palms up to protect the brachial plexus, a pillow goes under the knees to relieve the lumbar spine, and the heels and occiput are offloaded.
Trendelenburg tilts the head down about 15 to 30 degrees for pelvic, lower abdominal and laparoscopic surgery; it moves the viscera cephalad and splints the diaphragm, raises intracranial, intraocular and airway pressures, and causes facial and laryngeal oedema and aspiration — shoulder braces used to stop the patient sliding are the classic cause of brachial plexus injury.
Reverse Trendelenburg tilts the head up for upper abdominal, laparoscopic cholecystectomy, thyroid and head and neck surgery, with a padded footboard taking the weight; venous pooling in the legs drops the blood pressure and the operative site above the heart raises the risk of venous air embolism.
Lithotomy is used for perineal, vaginal, anorectal and urological work: hips flexed 80 to 100 degrees, thighs abducted less than 90 degrees, and both legs raised and lowered together by two people, because raising or lowering one at a time twists the lumbar spine and dropping both at once causes a sudden fall in venous return. The common peroneal nerve at the neck of the fibula (foot drop), the saphenous nerve at the medial condyle and well-leg compartment syndrome are the specific hazards.
Prone and jackknife (Kraske) positions are used for spinal and perianal surgery: chest rolls run from the clavicle to the iliac crest so the abdomen hangs free (a compressed abdomen raises intra-abdominal pressure, engorges the epidural veins and increases bleeding), the eyes must be checked and free of any pressure because of post-operative visual loss, and the breasts, genitalia, knees and toes are padded.
Lateral (kidney or Sims) position is used for nephrectomy, thoracotomy and hip surgery: an axillary roll is placed under the dependent chest wall just caudal to the axilla — never in the axilla itself — to protect the brachial plexus and axillary vessels, a pillow goes between the legs with the dependent leg flexed and the upper leg straight, and ventilation and perfusion mismatch because the dependent lung is perfused while the upper lung is ventilated.
The sitting or beach-chair (Fowler) position is used for posterior fossa and shoulder surgery; because the operative site is above the right atrium there is a real risk of venous air embolism, and the anaesthetist monitors with capnography and a precordial Doppler, so a sudden fall in end-tidal carbon dioxide is a positioning emergency, not a machine fault.
General rules for every position: pad the occiput, scapulae, elbows (ulnar nerve at the medial epicondyle), sacrum and heels; place the safety strap about 5 cm above the knees, loose enough for two fingers; keep the fingers clear of the table break; make sure no part of the patient touches a metal part of the table, because that becomes an exit point for diathermy current; move the anaesthetised patient slowly and recheck the blood pressure after every change of position.

OT positions

The positions of the operating team are the fixed places each member takes around the table so that the surgeon has an unobstructed line of work, the sterile field is never crossed and the anaesthetist keeps control of the airway. They are learned as a layout, but they are really a set of rules about where the sterile zone begins and ends and who may move where — most intraoperative contamination is a traffic and positioning failure rather than a scrubbing failure.

The surgeon stands on the patient's right for most open abdominal operations when right-handed, with the first assistant directly opposite; in laparoscopic cholecystectomy the American position places the surgeon on the patient's left with the assistant on the right, while the French position places the surgeon between the patient's abducted legs.
The scrub nurse stands opposite or just downstream of the surgeon with the Mayo table drawn across the patient and the back table behind her, keeps her hands between the level of the nipples and the waist and above table height, and never turns her back to the sterile field.
The anaesthetist and the anaesthesia machine occupy the head end; the drape screen at the neck divides the non-sterile anaesthetic zone from the sterile field, and nothing sterile is passed over or reached across the screen.
The circulating nurse works entirely outside the sterile field: she checks and opens sterile packs onto the field without touching the contents, positions the patient, connects suction, diathermy and the light, performs the counts with the scrub nurse, documents, and is the team's only link to the world outside the theatre.
Movement rules: sterile persons pass one another back to back or front to front keeping the field between them, face the sterile field at all times, and never lower their hands below waist level; unsterile persons face the sterile field when passing it and keep at least 30 cm away from it.
Only the front of the gown from chest to the level of the sterile field, and the sleeves from 5 cm above the elbow to the cuff, are considered sterile; the back, the area below the waist, the axilla and the cuff of the glove once the gown is removed are not, and the edge of any wrapper or the top 2.5 cm of a drape below table level is unsterile.
The table is set at the operating surgeon's elbow height, the overhead lights are focused from two directions so the surgeon's head casts no shadow, and the light is repositioned only by the sterile handle; theatre doors stay closed and traffic is kept to a minimum because each door opening disturbs the laminar airflow.

Cautery — mono vs bi-polar

Surgical diathermy (electrosurgery) passes a high-frequency alternating current, usually between about 300 kHz and 3 MHz, through tissue so that the heat generated at the point of highest current density cuts, coagulates or fulgurates it. Frequencies this high do not depolarise nerve and muscle, which is why the patient is not electrocuted; true cautery, by contrast, is a passively heated element with no current entering the patient at all, and the two words are not interchangeable.

In monopolar diathermy the current leaves a small active electrode, travels through the whole patient and returns to the generator through a large patient return (dispersive) plate; the heat is produced where the current density is high, so the fine tip cuts while the wide plate stays cool.
The return plate must sit on clean, dry, shaved-free, well-perfused muscle bulk close to the operative site (thigh, buttock, back), avoiding bony prominences, scar, hair, tattoos, metal implants and prostheses; partial contact or a peeling edge concentrates the current and produces a full-thickness skin burn under the plate.
In bipolar diathermy the current passes only between the two limbs of the forceps, so no plate is needed, far less power is used and there is little collateral spread; it is the choice on a digit, the penis, near the ureter or a nerve, and in the patient with a pacemaker or implantable defibrillator, but it coagulates rather than cuts.
Cutting current is a continuous low-voltage waveform that vaporises cells; coagulating current is an interrupted high-voltage waveform with a duty cycle of only a few per cent that desiccates and fulgurates; blend settings lie between the two, and using a higher power than needed is the commonest cause of collateral injury.
Fire is the hazard the nurse controls: alcohol-based skin preparation must be fully dry with no pooling under the drapes or in the umbilicus or groin before the diathermy is armed, the active electrode is holstered when not in use, and unprepared bowel containing methane and hydrogen can explode if diathermy is used to enter it.
In laparoscopy the extra hazards are insulation failure of the shaft outside the field of view, direct coupling to a metal instrument or the telescope, and capacitive coupling; the answer is to inspect the insulation, keep the whole active tip in view before activating, and use the lowest effective power in short bursts.
With a cardiac implantable device, use bipolar where possible; if monopolar is unavoidable, use short bursts at the lowest power, place the return plate so that the current path from the operative site to the plate does not cross the device or its leads, arrange preoperative interrogation and reprogramming with cardiology, and keep an external defibrillator and pacing available.
Surgical smoke is a biohazard carrying viable virus, bacteria and carcinogens; a smoke evacuator and high-filtration masks are used, and the plume is not simply vented into the room.

Sutures and knots

A suture is the material used to hold divided tissue in apposition until the wound has regained enough strength to hold itself, and it is classified as absorbable or non-absorbable, natural or synthetic, and monofilament or braided. The choice is not a matter of preference: it is a calculation of how long that particular tissue takes to regain strength against how much the material invites infection and reaction, which is why fascia gets a slowly absorbable or permanent suture and skin gets a fine monofilament that comes out.

Absorbable materials and how long they hold: plain catgut keeps useful strength for about 7 to 10 days and is absorbed in about 70 days; chromic catgut holds about 21 days; polyglactin 910 (Vicryl) retains about 75% of its strength at 2 weeks and 50% at 3 weeks and is absorbed by hydrolysis in 56 to 70 days; poliglecaprone (Monocryl) has lost most of its strength by 3 weeks and is absorbed in 91 to 119 days; polydioxanone (PDS) still holds about 50% at 4 weeks and is absorbed over 180 to 210 days.
Non-absorbable materials: silk is braided, handles and knots best of all but excites the most tissue reaction and wicks bacteria along its interstices; nylon (polyamide) is a springy monofilament used for skin; polypropylene (Prolene) is inert, never degrades and is the suture for vascular anastomosis and mesh fixation; stainless steel is used for the sternum and for the abdominal wall in the difficult closure.
Sizing runs 5, 4, 3, 2, 1, 0, then 2-0, 3-0 and onward to 11-0: the more zeroes, the finer the thread, so 5-0 is finer than 3-0 while a plain 1 is thicker than 0. Use the finest suture that will hold the tissue, because thicker material means more foreign body in the wound.
Needles: round-bodied (atraumatic) needles are used for bowel, vessel, fat and muscle because they separate fibres rather than cut them; cutting and reverse-cutting needles are used for skin, fascia and other tough tissue, and the reverse-cutting needle carries its cutting edge on the convex outer surface so that the pull is away from the wound edge; blunt needles are used on the liver and increasingly for fascia to reduce needlestick injury.
Knots: the square (reef) knot is the standard and the granny knot slips; the surgeon's knot adds a double throw to the first turn so it holds while the second is laid; springy monofilaments such as nylon, polypropylene and PDS need five or six throws to be safe, while braided silk and Vicryl hold with three; the throws must be laid flat and the tension must not strangle the tissue, because a suture that blanches the skin will cut through it.
Skin sutures are removed by site: face 3 to 5 days, neck 5 to 7, scalp, upper limb and trunk 7 to 10, and lower limb, back and any wound over a joint 10 to 14 days; add several days in diabetes, jaundice, malnutrition, steroid use and after radiotherapy, and use alternate removal with adhesive strip support if the edges look at all uncertain.
Abdominal fascial closure follows Jenkins rule — a continuous mass closure with a suture length at least four times the wound length, using a slowly absorbable or non-absorbable material; classic teaching takes bites 1 cm from the edge and 1 cm apart, while current evidence favours small bites of 5 mm at 5 mm intervals with a fine slowly absorbable suture to reduce incisional hernia.
In a contaminated or infected wound choose a monofilament over a braided suture, because bacteria hide in the interstices of a braid where phagocytes cannot follow; and remember that skin can also be closed with staples (fast, more expensive), adhesive strips or tissue glue for a clean linear wound under no tension.

Surgical site infection and prevention

A surgical site infection is an infection of the incision, the deep tissues or the organ and space that were opened or manipulated at operation, occurring within 30 days of surgery, or within 90 days for the implant procedures listed in the current CDC and NHSN surveillance definitions. It is the commonest healthcare-associated infection in surgical patients and roughly doubles the length of stay and the cost of an admission, and most of what prevents it is nursing work done in the hours before and during the operation rather than antibiotics given afterwards.

Three depths are defined: superficial incisional involves only skin and subcutaneous tissue, deep incisional involves fascia and muscle, and organ or space infection involves any part opened or manipulated at operation, such as an intra-abdominal collection after a colectomy. Each needs purulent drainage, an organism grown from an aseptically taken specimen, or a wound deliberately opened by the surgeon with signs of infection.
Risk tracks the wound class: about 1 to 2% for a clean wound, 5 to 10% clean-contaminated, 15 to 20% contaminated and 25 to 40% or more for a dirty wound; the NNIS risk index adds an ASA grade of 3 or more and an operating time longer than the 75th percentile for that procedure.
Prophylactic antibiotic is a single intravenous dose given so that the incision falls within 60 minutes of the infusion (120 minutes for vancomycin and fluoroquinolones), cefazolin 2 g being the usual agent, repeated after about two half-lives of operating (roughly 4 hours for cefazolin) or a blood loss above 1500 mL, and stopped at the end of the operation — continuing it for 24 hours does not lower infection and does select resistance.
Skin and hair: the patient bathes with soap or an antiseptic the night before, and hair is not removed at all unless it interferes with the incision; when it must go, clip it with electric clippers immediately before surgery, because razor shaving raises the infection rate by creating micro-abrasions that colonise overnight. Prepare the skin with 2% chlorhexidine in 70% alcohol applied in expanding circles and allowed to dry fully.
Intraoperative measures that matter: keep the core temperature above 36 degrees Celsius with a forced-air warmer and warmed fluids, keep the blood glucose below 200 mg/dL in diabetics and non-diabetics alike, give supplemental oxygen (WHO advises 80% inspired oxygen intraoperatively and for a few hours afterwards in the intubated patient), maintain perfusion and volume, and keep theatre door openings and staff traffic to a minimum.
Staphylococcus aureus is the commonest organism overall, and MRSA where there are risk factors; clean-contaminated abdominal and colorectal work adds Escherichia coli, Klebsiella, Enterococcus and Bacteroides fragilis. Nasal decolonisation with mupirocin plus a chlorhexidine wash is used for Staphylococcus aureus carriers before cardiac and orthopaedic implant surgery.
Treatment is drainage, not antibiotics: open the incision, release the pus, send pus or deep tissue rather than a superficial swab for culture, pack or dress the open wound and let it heal by secondary or delayed primary closure. Systemic antibiotics are added only when there is cellulitis extending more than 5 cm from the wound, systemic upset, or an immunocompromised patient.
Timing gives the diagnosis in the post-operative fever, remembered as the five Ws — Wind (atelectasis and pneumonia, day 1 to 2), Water (urinary infection, day 3 to 5), Wound (day 4 to 7), Walking (deep vein thrombosis, day 5 to 7) and Wonder drugs or What we did (drug fever, line infection and collections from day 7 onward); an anastomotic leak typically declares itself on day 5 to 7 with tachycardia and ileus before any fever.

Types of wound

A wound is any break in the continuity of tissue, and surgery classifies it in two ways that decide management: by the degree of contamination present at the time of the operation, using the four Altemeier classes adopted by the CDC, and by the way it is allowed to close, as primary, secondary or tertiary intention. The class is assigned at the end of the operation and recorded, because it predicts the infection rate, sets how long antibiotics run, and decides whether the skin is closed at all.

Class I, clean: an elective, atraumatic, uninfected wound with no inflammation, no break in sterile technique and no entry into the respiratory, alimentary or genitourinary tract — thyroidectomy, hernia repair, mastectomy, most vascular and joint surgery; the expected infection rate is about 1 to 2%.
Class II, clean-contaminated: the respiratory, alimentary, genital or urinary tract is entered under controlled conditions without unusual spillage — elective cholecystectomy, prepared bowel resection, non-perforated appendicectomy, hysterectomy; the expected rate is about 5 to 10%.
Class III, contaminated: fresh accidental wounds less than about 6 hours old, a major break in sterile technique such as open cardiac massage, gross spillage from the gastrointestinal tract, or an incision into acutely inflamed tissue without pus; the expected rate is about 15 to 20%.
Class IV, dirty or infected: old traumatic wounds with retained devitalised tissue, faecal contamination, an existing clinical infection, or a perforated viscus with pus already present — the organism that will cause the post-operative infection is already in the wound before the knife touches it, and the rate is 25 to 40% and above.
By closure: primary intention is a clean wound with apposed edges healing with minimal granulation and a fine scar; secondary intention is an open wound left to fill with granulation tissue, contract and epithelialise, used for large, contaminated, infected or cavity wounds and giving more scar and contracture; tertiary or delayed primary closure leaves the wound open for 3 to 5 days, and sutures it once it is clean — the standard answer for the skin of a contaminated laparotomy or a dirty traumatic wound.
By mechanism, wounds are incised, lacerated, abraded, punctured or penetrating, contused, avulsed, degloved, crushed or bites; a human or cat bite, a deep puncture and any wound more than 6 hours old with devitalised tissue is treated as contaminated and is never closed primarily.
Every contaminated and dirty wound needs formal wound toilet before anything else — copious irrigation with normal saline, removal of foreign material and excision of dead tissue, because debridement decides the outcome far more than the choice of antibiotic.
Tetanus prophylaxis follows the wound class and the immunisation history: for a clean minor wound give a tetanus toxoid-containing vaccine if fewer than three doses or unknown, or if the last dose was over 10 years ago; for all other wounds give the vaccine if fewer than three doses, unknown, or the last dose was over 5 years ago, and add human tetanus immunoglobulin 250 IU (500 IU if the wound is heavily contaminated or more than 24 hours old) when the primary course is incomplete or unknown.

Plastic surgery — skin graft, Humbys knife

A skin graft is skin completely detached from its donor site and laid on a recipient bed, where it survives for the first 48 hours by soaking up plasma (imbibition), then by the linking of cut vessel ends (inosculation) and finally by ingrowth of new vessels; a flap, by contrast, brings its own blood supply with it. Grafting matters because a wound too large to close directly would otherwise granulate and contract for months, and early cover reduces fluid and protein loss, pain, infection and contracture — which is why the burns patient is grafted rather than dressed indefinitely.

A split-thickness (Thiersch) graft takes the epidermis and part of the dermis. The thinner the graft the more reliably it takes and the more it contracts afterwards; the thicker the graft the better its colour, texture and resistance to contraction but the less certain the take — that trade-off is the whole of graft selection.
A full-thickness (Wolfe) graft takes the epidermis and the whole dermis, is harvested from post-auricular skin, the upper eyelid, the supraclavicular fossa, the groin or the flexor crease of the elbow, and the donor site must be closed directly, so the graft is necessarily small; it is used on the face, the eyelid and the flexor surfaces of the hand because it contracts least.
A Humby knife is a hand-held guarded knife with an adjustable roller that sets the thickness of a split-thickness graft; the skin is lubricated and stretched flat between two boards and the knife is used with a steady sawing motion, while a powered dermatome gives a more uniform graft. Meshing the graft at 1 to 1.5 or 1 to 3 expands the area covered, allows exudate to escape and lets the graft conform to an irregular bed, at the price of a permanent mesh pattern.
The split-thickness donor site — usually the anterolateral thigh, buttock or back — heals by re-epithelialisation from the retained hair follicles and sweat glands in about 10 to 14 days and can be re-harvested afterwards; it is dressed with a single occlusive or paraffin dressing left undisturbed, and it is more painful than the grafted area itself, which patients should be warned about.
Graft take is assessed at about day 5, when a graft that is pink and adherent has taken. The commonest cause of failure is a haematoma or seroma lifting the graft off its bed, followed by shear and movement, infection and a poor bed; beta-haemolytic Streptococcus in the wound is an absolute contraindication to grafting because its streptokinase digests the fibrin that holds the graft down.
Some beds will not take a graft at all and need a flap: bare cortical bone without periosteum, bare tendon without paratenon, bare cartilage without perichondrium, exposed metalwork or joint, and heavily irradiated tissue.
Nursing care: immobilise and elevate the grafted part, use a tie-over bolster dressing where the surface is irregular, leave the first dressing undisturbed until about day 5 unless there is pain, fever or smell, handle the limb without shear, and once healed start moisturising, massage, sun protection and pressure garments to control hypertrophic scarring for up to a year.

Wound healing stages

Wound healing is the ordered overlapping sequence of haemostasis, inflammation, proliferation and remodelling by which injured tissue is repaired, usually with a scar rather than with identical tissue. It matters because every surgical instruction is really a statement about which phase the wound is in — when the dressing can come off, when the sutures come out, when the patient may lift, and why a wound that has stopped progressing needs a reason found.

Haemostasis, in the first minutes to hours: vasoconstriction, platelet adhesion and aggregation on exposed collagen and the coagulation cascade produce a fibrin plug that both stops the bleeding and forms the scaffold for the cells that follow; the platelets release platelet-derived growth factor and transforming growth factor beta, which call in the next wave.
Inflammatory phase, day 0 to about day 3 to 5: vasodilatation and increased capillary permeability give the classic redness, heat, swelling, pain and loss of function. Neutrophils arrive within 24 to 48 hours to kill bacteria and clear debris, and macrophages from about day 2 to 3 take over — the macrophage is the key cell of healing, because a wound can heal without neutrophils but not without macrophages.
Proliferative phase, about day 3 to day 21: fibroblasts lay down type III collagen, angiogenesis produces the red capillary loops of granulation tissue, and epithelial cells migrate in from the wound margins and from surviving hair follicles. In a sutured wound the epithelial bridge is complete within 24 to 48 hours, which is why the original dressing can come off at 48 hours; myofibroblasts begin to contract an open wound from about day 5.
Remodelling or maturation, from about 3 weeks to 1 or 2 years: type III collagen is replaced by stronger type I until the normal dermal ratio of roughly 4 to 1 is restored, the fibres are cross-linked and realigned along the lines of stress, the capillaries regress and the scar becomes pale, flat and soft.
Wound strength is the number the exam wants: about 5% of final strength at 1 week, 20% at 3 weeks, 50% at about 3 months, and a plateau at 70 to 80% of the original tissue strength — a scar never regains full strength, which is why abdominal patients avoid heavy lifting for 6 weeks and why fascia needs a suture that holds for at least a month.
Three modes of healing: primary intention where clean apposed edges heal with minimal granulation and a fine scar; secondary intention where an open wound fills with granulation tissue, contracts and epithelialises, giving more scar and more contracture; and tertiary or delayed primary closure where a contaminated wound is left open for 3 to 5 days and then sutured once it is clean.
Local factors that delay healing are infection above about 100,000 organisms per gram of tissue, ischaemia and hypoxia, a foreign body, haematoma, movement or tension across the wound, previous radiotherapy and repeated trauma from dressings. Systemic factors are age, protein-energy malnutrition and deficiency of vitamin C (needed for hydroxylation of collagen), zinc and vitamin A, diabetes, uraemia, jaundice, anaemia, smoking, obesity, corticosteroids, chemotherapy and immunosuppression; the healing-inhibiting effect of steroids is partly reversed by vitamin A.
Abnormal scars: a hypertrophic scar stays within the boundary of the original wound, appears within 4 to 8 weeks, and usually regresses over months; a keloid grows beyond the original wound margin, appears later, does not regress, recurs after simple excision, and is commoner in darker-skinned patients and over the sternum, shoulder, earlobe and upper back. Treatment is silicone sheeting, pressure therapy and intralesional triamcinolone, with excision only when combined with an adjuvant.
The timing of wound complications is examinable in itself: haematoma in the first 24 to 48 hours, seroma at days 3 to 7, wound infection at days 4 to 7, and wound dehiscence or burst abdomen at about days 5 to 10, heralded by a pink serosanguinous discharge before anything appears to be wrong.

Local anaesthesia

Local anaesthesia is the reversible blockade of impulse conduction in a nerve by a drug that closes voltage-gated sodium channels from inside the axon, so sensation is lost over a defined area while the patient remains fully awake. It matters because the same drug that makes a suture line painless will, if the maximum dose is exceeded or a vessel is entered, cause convulsions and cardiac arrest — so the nurse who draws it up must be able to convert the maximum dose from milligrams into millilitres of the ampoule in front of her.

Amides are metabolised in the liver and have two letter 'i's in their names — lignocaine (lidocaine), bupivacaine, ropivacaine, prilocaine; esters are hydrolysed by plasma cholinesterase to para-aminobenzoic acid and cause almost all true allergic reactions — procaine, chloroprocaine, tetracaine, cocaine and benzocaine.
Maximum safe doses: lignocaine 4.5 mg/kg plain (about 300 mg in an adult) and 7 mg/kg with adrenaline (about 500 mg); bupivacaine 2 mg/kg plain (about 150 mg) and up to 3 mg/kg with adrenaline. Some texts quote a more conservative 3 mg/kg for plain lignocaine, so follow the institution's figure and never exceed 7 mg/kg with adrenaline.
Concentration arithmetic is examinable: a 1% solution contains 10 mg/mL, so 2% is 20 mg/mL and 0.5% is 5 mg/mL, and adrenaline 1:200,000 is 5 micrograms per mL. A 70 kg adult may therefore receive about 31 mL of plain 1% lignocaine (315 mg) or about 49 mL of 1% with adrenaline (490 mg).
Adrenaline 1:200,000 vasoconstricts, so it slows systemic absorption, prolongs the block, raises the permissible dose and reduces bleeding in the field; it is avoided in uncontrolled hypertension, ischaemic heart disease and thyrotoxicosis, and traditionally avoided in end-artery territories — fingers, toes, penis, ear lobe and tip of the nose.
Onset and duration: lignocaine acts within 2 to 5 minutes and lasts 1 to 2 hours (up to 3 to 4 with adrenaline), while bupivacaine takes 10 to 15 minutes and lasts 4 to 8 hours; bupivacaine is the most cardiotoxic of the common agents, must never be injected intravenously and is never used for intravenous regional anaesthesia (Bier's block).
Local anaesthetic systemic toxicity is dose- and rate-dependent and progresses through perioral tingling, a metallic taste, tinnitus, light-headedness and blurred vision, then muscle twitching and convulsions, then coma, respiratory arrest, arrhythmias and cardiovascular collapse.
Treating toxicity: stop injecting, call for help, secure the airway and give 100% oxygen, control seizures with a benzodiazepine, start CPR with reduced-dose adrenaline (boluses of 1 microgram/kg or less) if arrest occurs, avoid lignocaine and vasopressin as antiarrhythmics, and give 20% lipid emulsion — 1.5 mL/kg as a bolus over 2 to 3 minutes followed by an infusion of 0.25 mL/kg/min — which is why a lipid rescue kit is stocked wherever these drugs are used.
Safe practice at the bedside: use the lowest effective concentration, aspirate before every injection and inject slowly in divided doses, keep talking to the patient so early symptoms are heard, have resuscitation equipment and monitoring to hand for large-volume blocks, and record on the chart the total dose already given before any top-up is drawn.
Other routes and their own warnings: topical EMLA cream needs 45 to 60 minutes under an occlusive dressing before venepuncture; prilocaine and benzocaine in large doses cause methaemoglobinaemia, treated with methylene blue; and spinal or epidural blocks cause hypotension, bradycardia and urinary retention rather than systemic toxicity.

Bariatric surgery

Bariatric or metabolic surgery is the group of operations that reduce gastric capacity and, in some procedures, bypass a length of small intestine, so that weight is lost and obesity-related disease — above all type 2 diabetes — improves through restriction, altered absorption and changed gut hormone signalling. It matters to nursing because the long-term result depends far more on dietary discipline, lifelong supplementation and follow-up than on the operation itself, and because the leak that kills in the first week announces itself only as a tachycardia.

Traditional NIH selection is a BMI of 40 kg/m2 or more, or 35 or more with an obesity-related comorbidity such as type 2 diabetes, obstructive sleep apnoea, hypertension or arthropathy, after supervised weight-loss attempts have failed; the 2022 ASMBS/IFSO statement widens this to a BMI of 35 regardless of comorbidity and 30 to 34.9 with metabolic disease, and recommends offering surgery to Asian patients from a BMI above 27.5, because metabolic disease appears at a lower BMI in Asian populations.
The operations: sleeve gastrectomy, in which about 80% of the greater curve is removed (restrictive, now the commonest worldwide); Roux-en-Y gastric bypass, with a 30 mL pouch and a Roux limb (restrictive and malabsorptive, the best choice where reflux or diabetes dominates); one-anastomosis or mini gastric bypass; adjustable gastric banding, now largely abandoned; and biliopancreatic diversion with duodenal switch, the most malabsorptive and the most nutritionally demanding.
Expected results: 25 to 30% of total body weight lost by 12 to 18 months, remission or major improvement of type 2 diabetes in a majority of patients — often before much weight has been lost, because of the incretin effect — and improvement in sleep apnoea, dyslipidaemia, hypertension and fertility.
Early complications: anastomotic or staple-line leak, typically on days 2 to 7, where a sustained tachycardia above 120 a minute, tachypnoea, left shoulder-tip pain or a sense of impending doom comes before fever and peritonism, because an obese abdomen localises poorly; also bleeding, venous thromboembolism (the leading cause of death, so early mobilisation and extended prophylaxis are routine) and rhabdomyolysis after long operations.
Late complications: internal hernia with small bowel obstruction after a bypass — any bypass patient with abdominal pain needs a CT — marginal ulcer (smoking and NSAIDs are forbidden for life), stomal stricture, gallstones from rapid weight loss, and dumping syndrome, which is early at 10 to 30 minutes with cramps, diarrhoea, flushing and palpitations from a hyperosmolar load, and late at 1 to 3 hours with sweating, tremor and hunger from reactive hypoglycaemia.
Lifelong nutrition: 60 to 80 g of protein a day taken first at every meal, small volumes chewed thoroughly, drinks separated from meals by about 30 minutes, and lifelong supplements — a complete multivitamin, vitamin B12 (high-dose oral or 1000 micrograms intramuscularly on a monthly to three-monthly schedule after bypass, because intrinsic factor and acid are bypassed), iron with vitamin C in menstruating women, calcium citrate 1200 to 1500 mg in divided doses with vitamin D, folate and thiamine.
Persistent vomiting after bariatric surgery is a thiamine emergency: Wernicke's encephalopathy can develop within weeks, so intravenous thiamine is given before any glucose-containing fluid, never after it.
Pregnancy is deferred for 12 to 18 months while weight is falling and contraception is advised, because fertility improves quickly; medicines may need to be liquid or crushed, and extended-release preparations are avoided because absorption is unpredictable.

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