Mrcs part a essential revision notes book 1 pdf


 

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Mrcs Part A Essential Revision Notes Book 1 Pdf

'In a nutshell' sections highlight important lists and vital points, and the text is clearly laid out with illustrations to aid understanding. Vital for. MRCS Part A Essential Revision Notes Book 1. MRCS Part A Book 1. 12 MB PDF I'd like to thank you for clicking like and G+1 buttons. MRCS PART A ESSENTIAL. REVISION NOTES. BOOK 1. Edited by. Claire Ritchie Chalmers. BA PhD FRCS. Catherine Parchment Smith. BSc MBChB FRCS.

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The Lee Index is a predictor of individual cardiac risk and contains six independent clinical determinants of major perioperative cardiac events: A history of ischaemic heart disease IHD A history of cerebrovascular disease Heart failure Type 1 diabetes mellitus Impaired renal function High-risk surgery The presence of each factor scores 1 point. FBC Correction of anaemia is essential because it compromises cardiac and respiratory function and is not well tolerated in patients with ischaemic disease May require iron supplements or even staged transfusion.

CT detection of coronary vessel calcium and MR angiography can also be performed. Look for previous infarct. Dobutamine stress testing or cardiac perfusion scanning may also be used for specialist investigation.

Acts as a baseline for comparison in the future. Exercise testing: Assessing myocardial ischaemia ECG: Assessing LV function Echocardiography: It assesses peak oxygen consumption and anaerobic threshold and provides an objective measurement of functional capacity. Always bear in mind that a patient may need his or her cardiac condition optimised by a cardiologist.

It may be necessary to arrange angioplasty.

Intraoperative considerations for patients with cardiac disease Cardiac effects of general anaesthesia GA include: Vasodilatation blocks sympathetic outflow May be combined with GA for pain control Ischaemic heart disease Preoperative considerations Known risk factors must be identified in the history eg smoking. Remember that ischaemia may be silent. Combined cardiopulmonary testing CPET: Obviously the risk must be balanced against any potential benefit of a surgical procedure.

A careful examination of the heart and lungs must be performed. Clinically look for mitral facies. Symptomatic aortic stenosis AS produces syncope. Must be given prophylactic antibiotics for invasive procedures. Poorly controlled hypertension in the immediate pre-op period predisposes the patient to perioperative cardiac morbidity and must be avoided. Newly diagnosed hypertension must be assessed for possible reversible aetiological factors eg renal disease. Minimise fluid overload and changes in cardiac rate.

On examination there may be an ejection systolic murmur radiates to the carotids. After appropriate pain relief take three separate BP readings.

Prophylactic antibiotics are important. Chronic long-standing hypertension puts the patient at increased risk of cardiovascular disease. These patients are also at higher risk of hypertensive crises. LVH whether clinically. Mitral stenosis May predispose to pulmonary hypertension and right cardiac failure. These conditions need to be excluded or optimised. They may also be on long-term anticoagulation. Valvular disease Patients with valvular disease are susceptible to endocarditis if they become septic.

Indication of the need for and the speed of intervention. Continuous or demand model? If continuous. Due to short-circuiting of the electrical impulses of the atria resulting in disorganised muscle contraction.

Arrhythmias Atrial fibrillation Common arrhythmia giving an irregularly irregular beat. Causes reduced efficiency of the atria to pumpprime the ventricles. AF predisposes to thrombotic events blood in the auricles of the atria moves sluggishly and forms clots which are then expelled into the systemic circulation — commonly causing a cerebrovascular accident [CVA] Pacemakers and implanted ventricular defibrillators Problems during the surgical period include: Interactions with diathermy current: Respiratory disease commonly includes chronic pulmonary obstructive disease COPD.

Unipolar diathermy current may pass down pacing wires. Chronic obstructive pulmonary disease and asthma COPD is pathologically distinct. Always use bipolar diathermy if possible and check for deleterious effects. Cardiac failure Due to acute or chronic ischaemic or valvular disease Exercise tolerance is a good indictor of cardiac reserve. Patients should have the pacemaker evaluated by cardiology before and after surgery because they will be able to assess and advise on any changes required to the settings.

It may be difficult to determine the importance of each condition in an individual. Generalised airflow obstruction is the dominant feature of both diseases.. Input from respiratory physicians is advisable. Postoperative physiotherapy at least three times per day is essential. Bronchiectasis and cystic fibrosis Preoperative sputum culture and ABG are needed to act as baseline information. They may require preoperative chest radiography.

Smoking Short-term effects of smoking Nicotine increases myocardial oxygen demand. This is not usually a problem. Active TB should be considered in recent immigrants from areas where TB is endemic.

Tuberculosis Many patients have evidence of old TB disease or previous anti-TB surgery on chest radiography. Active physiotherapy. Analgesia Optimise analgesia using a combination of local and regional techniques to allow deep breaths and coughing as required. In patients with known respiratory disease.

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Remember local infiltration intraoperatively. Diabetes mellitus Thyroid problems Parathyroid problems Preoperative management of diabetes mellitus.. Infiltration of local anaesthesia LA. Anaesthetic agents Anaesthetic agents have the following effects: Reduce muscle tone and thus functional residual capacity Increase airway resistance and reduce lung compliance Cause atelectasis in dependent zones of the lung.

Postoperatively monitor BM regularly and institute a sliding scale of intravenous insulin if the patient is unable to tolerate an oral diet immediately. Restart regular insulin once the patient is eating and drinking normally and observe closely for sepsis. This is a syndrome of excessive and uncontrolled thyroxine release which may result in hyperthermia.

Preoperative management of thyroid problems For more details of thyroid physiology. Myocardial ischaemia Hypotension Hypothermia Hypoventilation. Problems associated with thyroid disease include: Local effects: Restart patients back on their normal oral hypoglycaemic regimen as soon as an enteral diet is recommenced.

Only discharge the patient once his or her control is within recognised limits because the insulin requirements may well increase transiently after a stressful stimulus such as surgery. Management of type 1 diabetes mellitus Achieve good pre-op control and admit the patient the night before surgery.

Book 2. Hypoglycaemia Hyponatraemia Acidosis Preoperative management of parathyroid problems For more details of parathyroid physiology. Endocrine surgery. Increased risks of: Renal impairment needs careful rehydration and fluid balance. Typical symptoms include tremor. Perioperative issues include: Compromised respiratory function Urinary retention Confusion. Consider individual special needs when arranging analgesia eg may not cope with patient-controlled analgesia..

They are at risk of drug interactions. Preoperative management of epilepsy Aim to avoid seizures in the perioperative period by minimising disruption to the maintenance regimen of medication: Patients with cirrhosis and liver disease do badly and have a high mortality rate with elective surgery. Problems to anticipate include: Domperidone is a good antiemetic because it does not have significant antipyramidal effects.

Hypoalbuminaemia impairs drug binding and metabolism and may lead to elevated serum levels. Bleeding due to coagulopathy Encephalopathy Increased risk of infection Increased risk of renal failure Hypoglycaemia Acid—base and electrolyte imbalances Underlying cause eg malignancy.

Hepatorenal syndrome has a very poor prognosis. Drug metabolism Many drugs. IX and X. Clotting Due to a decrease in vitamin K absorption in cholestatic jaundice. There may be sodium retention and hypokalaemia due to secondary hyperaldosteronism. This will cause the oxygen dissociation curve to shift to the left and decrease oxygen delivery to the tissues.

Acid—base balance A combined metabolic and respiratory alkalosis may occur. Hepatorenal syndrome Renal failure may be precipitated by hypovolaemia. Details of the causes.

Patients in established renal failure pose specific problems in perioperative care. Fluid and electrolyte. Severe uraemia can directly affect the cardiovascular. Orthopaedic Surgery. Veins on the hands can be used. Rheumatoid arthritis RA is a common relapsing and remitting autoimmune condition resulting in progressive joint swelling and deformity see Chapter 9.

Fluid overload. Peripheral neuropathy: Respiratory disease: Renal impairment: Avoid nephrotoxic drugs in those with borderline or impaired renal function. Increased risks at time of surgery for RA patients Cardiac: Classification of renal failure Prerenal.

Nutritional depletion pre- and post-surgery increases morbidity and mortality. Subluxation can result in: Malnutrition may be due to: Decreased intake Increasingly catabolic states Impaired digestion or absorption of nutrients Nutritional support improves outcome and follows a hierarchy: Therefore it is not an absolute marker for nutritional status. Nutritional requirements Daily nutritional requirements are shown in the table. B series. The postoperative catabolic state and the stress inhibition of the normal ketotic response can cause muscle metabolism and weaken the patient.

K Trace minerals: Many patients especially those with chronic disorders. Malnutrition in hospital patients is common: Poor wound healing and dehiscence Immunocompromise leading to infection chest and wound Organ failure Causes of malnutrition in the surgical patient Decreased intake Symptoms such as loss of appetite.

Surgery may induce anorexia and temporary intestinal failure. Hypercatabolic states Figure 1. Increasingly catabolic state Due to disease process. Obesity Obese patients are at increased risk of surgical complications for many reasons. Surgical risks of obesity. Respiratory Decreased chest wall compliance. Aspiration Increased gastric volume and high intra-abdominal pressure predispose to gastric aspiration.

Nutritional support Tailored to the protein. Enteral tube options include: Hyperglycaemia insulin resistance Hypertension and ischaemic heart disease Gallstones Osteoarthritis For elective surgery in obese patients. It follows a hierarchy. If the patient cannot take enough nutrients in orally. Oral supplementation Can be used between or instead of meals Variety available milk- or fruit-juice-based High in protein and calories Not all contain micronutrients Examples include Complan Enteral tube feeding Enteral feeding is the best route because it preserves GI mucosal integrity.

This may be useful in patients who. Polymeric whole protein. Catheter complications Risks of insertion Thrombosis Infection. Feeding may be cyclical or continuous. Feeding is via venous access. Peripheral vein long line.

Postoperative Management and Critical Care Complications of enteral feeding tubes Feeding tube displaced or blocked Metabolic hyperglycaemia. Metabolic complications Hyperglycaemia Electrolyte and fluid imbalance Hepatic dysfunction Immunocompromise Metabolic bone disease Nutritional planning in surgical patients Preoperative considerations Dietitian pre-op assessment of high-risk patients Encourage increased oral intake Oral supplementation high-protein and high-calorie drinks.

Colorectal surgery Traditionally the postoperative feeding regimen for bowel surgery was a stepwise progression guided by improving clinical signs eg passing of flatus thus: This has changed in recent years. This has lead to a number of different models for predicting risk: There have been some reports of overprediction of mortality risks which has led to specialty-specific modifications: Online gives an estimate of reduction in the risk of death from breast cancer in patients undergoing chemotherapy.

Many surgeons will then do a water contrast swallow on day 10 of high-risk anastomoses before allowing oral feeding. The POSSUM score uses 12 physiological and 6 surgical variables for its calculation and can be used pre- and postoperatively to give an initial estimate and calculation of individual risk. Increasingly risk assessment has been tailored to combine underlying comorbidity with the type of surgery proposed. Upper GI surgery Oesophageal and gastric resections are typically combined with a feeding jejunostomy placed intraoperatively.

SECTION 3 Principles of anaesthesia Anaesthesia is the rendering of part local anaesthesia or all general anaesthesia of the body insensitive to pain or noxious stimuli.. Adrenaline may be used with LAs to slow systemic absorption and prolong duration of action.

Dosage of local anaesthetic agents: Local toxicity Inflammatory response Nerve damage from needle or intraneural injection Systemic toxicity Allergy May occur from overdosage.

Topical local anaesthetic This is in the form of a cream or a spray and is used for routine procedures where only superficial anaesthesia is required. Procedure box: Give IV fluids and consider inotropic support. EMLA cream before cannulation in children Lidocaine gel before urethral catheterisation Xylocaine spray before gastroscopy Infiltration of local anaesthesia This is used typically for removal of small skin lesions.

Remember that even lidocaine takes 10—20 minutes to take full effect Use leftover local to infiltrate if the patient reports sensation. Drug toxicity can be local or systemic. This may involve blocking a nerve that supplies the area. An entire finger or toe can be made completely numb by injecting a millilitre or two of LA just to either side of the proximal phalanx at the level of the web space.

Brachial plexus blocks may be performed at different levels: These blocks are good for postop pain relief because they last for several hours.

A ring block is a type of field block where the area to be blocked is a digit or the penis. Brachial plexus block The brachial plexus is formed from the nerve roots C5—T1 which unite to form the main trunks upper. These subdivide into cords as they enter the axilla. Figure 1. A ring block can be used for manipulation of dislocated fingers. The cords subdivide as the plexus passes through the axilla. The nerve runs here with the digital artery and vein.

Deep infiltration of LA at this point will produce a femoral block note: The femoral nerve then divides in the femoral triangle and supplies the muscles of the anterior thigh. It lies on the iliopsoas as it passes under the inguinal ligament to enter the thigh. It undergoes early organisation into common peroneal and tibial portions.

The femoral nerve lies at a point that is 1 cm lateral to the pulsation of the femoral artery as it exits from under the inguinal ligament and 2 cm distal to the ligament.

They usually divide in the distal third of the thigh. Sciatic block The sciatic nerve arises from the lumbosacral nerve roots L4—S3 and exits under the biceps femoris muscle. This is suitable for analgesia covering the anterior thigh. Sciatic nerve blocks may be of slow onset up to 60 minutes so be patient with your anaesthetist. The intercostal nerve runs with the vascular bundle under the overhanging edge of the rib.

The sciatic nerve block can be performed by a lateral. Inject local anaesthetic note: Exsanguinate limb eg Eschmark bandage Apply double-cuff tourniquet with padding Inflate upper cuff to approximately mmHg Inject approximately 40 ml 0.

It is contraindicated in patients who are anticoagulated or septic. Spinal anaesthesia Useful for lower abdominal. The sciatic nerve lies 2 cm lateral to the ischial tuberosity at the level of the greater trochanter. Level is controlled by: Initial level of placement Patient positioning eg head-down tilt Volume and concentration of anaesthetic Level is described by the dermatome affected: Nipples T5 Umbilicus T Situated at level of nerve roots supplying surgical site lumbar for pelvic surgery.

Inguinal ligament T12 High block may cause respiratory depression. Allows for rapid recovery and avoids GA. Supplemental oxygen mask or nasal cannulae Cardiovascular: ECG leads and monitor Respiratory: Sedation is the administration of drug s to alleviate discomfort and distress during diagnostic and therapeutic interventions..

Be prepared for adverse reactions by ensuring the following: Sedation can be used: ASA grading estimation of risk for anaesthesia and surgery Class 1 Normal healthy individual Class 2 Patient with mild systemic disease Class 3 Patient with severe systemic disease that limits activity but is not incapacitating Class 4 Patient with incapacitating disease that is a constant threat to life Class 5 Moribund patient not expected to survive.

General anaesthesia induces Narcosis unconsciousness Analgesia Muscle relaxation It does this in a controlled and reversible manner. Stages of general anaesthesia Pre-op assessment and preparation Induction and muscle relaxation Maintenance and monitoring Recovery Postop monitoring and transfer Preoperative anaesthetic assessment The anaesthetist will assess the patient fully preoperatively.

ECG monitoring and resuscitation facilities available. It may be intravenous or inhalational. It is a negative inotrope and can result in a drop in BP. There is often associated respiratory depression. Steroids Prophylactic antibiotics Anticoagulants Immunosuppressants eg if undergoing transplantation Induction of general anaesthesia This is the administration of drug s to render the patient unconscious before commencing surgery.

Thiopental sodium is a commonly used induction agent. It is a phenol derivative that appears as a white aqueous emulsion. IV induction agents are also used for maintenance of anaesthesia. It causes a smooth and rapid induction but has a narrow therapeutic window and overdose may cause cardiorespiratory depression.

It sensitises the pharynx and cannot be used with laryngeal airways Propofol is more expensive than thiopental but has the advantage of a slight antiemetic effect. It is given in an alkaline solution pH It causes vasodilatation and is a negative inotrope.

IV induction agents are liquid-soluble. The IV route is quicker. It is a barbiturate that appears as a pale-yellow powder with a bitter taste and a faint smell of garlic. Inhalational anaesthetics may also be used for induction and are discussed later in this chapter. It is the most rapid-acting of all the muscle relaxants and is therefore useful when rapid tracheal intubation is required crash induction.

For a discussion of intubation see Chapter 3. The main example is suxamethonium. As it acts on the acetylcholine receptor there is an initial period of muscle fasciculation that may be painful and distressing to the patient.

It has a duration of 2—6 minutes in normal individuals. Its action cannot therefore be reversed. Complications of induction agents Complications include: Hypotension Respiratory depression Laryngeal spasm Allergic reactions Tissue necrosis from perivenous injection The effects are especially pronounced in hypovolaemic patients. This has a structure similar to two acetylcholine molecules and acts in the same way as acetylcholine at the neuromuscular junction. Muscle relaxants Depolarising muscle relaxants Depolarising muscle relaxants work by maintaining muscle in a depolarised or relaxed state.

Contraindications include previous allergy and porphyria. The rate of hydrolysis by plasma cholinesterase is. Complications of depolarising muscle relaxants Muscle pain Hyperkalaemia Myoglobinaemia Bradycardia Hyper- or hypotension Malignant hyperpyrexia. Other benzylisoquinoliniums include cisatracurium and gallamine Vecuronium is an aminosteroid of intermediate duration. It does. Maintenance of general anaesthesia Inhalational anaesthetics are usually used for maintenance of anaesthesia.

Atracurium undergoes non-enzymatic metabolism independent of hepatic or renal function and thus has a safety-net advantage for critically ill patients. Contraindications of depolarising muscle relaxants Patients prone to hyperkalaemia.

Atracurium or benzylisoquinolinium provides intermediate duration. Similar to all inhalational anaesthetics. Airway management and intubation may be difficult because of: Abnormal anatomy eg small mouth.

This usually settles spontaneously but a search for other causes eg Candida spp. Trauma to structures in the mouth. Failed intubation with inability to ventilate necessitates an alternative airway eg surgical or needle cricothyroidotomy. Apnoea common Patient monitoring during anaesthesia Patient monitoring during anaesthesia These are the recommendations for standards of monitoring of the Association of Anaesthetists of Great Britain and Ireland.

Optimal head position Pressure on the larynx Bougie Fibreoptic intubation may be performed awake Alternatives such as laryngeal mask Failed intubation may require the procedure to be abandoned.

Dislodged teeth may be aspirated.

Minor complications include: Death 1 in Gastric content aspiration Hypoxic brain injury MI Respiratory infection Problems with anaesthetic drugs Anaphylaxis This is a severe allergic reaction to an epitope which is characterised by massive release of histamine and serotonin. Commonly occurs as a reaction to muscle relaxants.. IV administration of chlorpheniramine 10—20 mg. Signs include hyperthermia. Pathology of malignant hyperpyrexia This condition may be triggered by all inhalational anaesthetics.

MRCS Part A Essential Revision Notes Book 2

It is a rare life-threatening condition 1 in which requires recognition and treatment. There is an increase in oxygen demand and CO2 production leading to a metabolic acidosis. Hyperventilation will help reduce PaCO2. The patient will need to be nursed on ITU and carefully monitored for signs of renal failure. Surface cooling and cool IV fluids may be administered. The patient and family must be counselled as to further risks and the possibility of genetic inheritance.

Even patients undergoing a regional block should be starved preoperatively in case there are complications and the anaesthetic has to be converted to a full GA. Respiratory complications Airway obstruction May be due to: Postoperative Management and Critical Care.

Surgical Technique and Technology. The three Ps of patient care in theatre are: Muscle injuries Pressure-area injury Risk factors: Pressure injuries on the sphere itself which can result in blindness are more likely if the patient is placed prone and measures should be taken to ensure that all pressure is transmitted through the bony prominences of the orbit Nerve injury Risk factor: Try to imagine that the patient is your relative and deal with him or her in a way that you feel is acceptable.

Place tape over rings or body piercings to protect site and ensure that there is no patient contact with metal parts of the operating table.

MRCS Part A: Essential Revision Notes Book 1 PDF Free Download

In particular: The epidermis is supported and nourished by a thick underlying layer of dense. These natural tension lines lie at right angles to the direction of contraction of underlying muscle fibres. All skin has the same basic structure. The external surface of the skin consists of a keratinised squamous epithelium called the epidermis.

Hair follicles. The dermis is attached to underlying tissues by a layer of loose connective tissue called the hypodermis or subcutaneous layer.

The skin is an enormously complex organ. A core knowledge of skin anatomy and physiology is essential to understand fully the processes involved in wound healing. It is constantly regenerating. See Figure 2. The four main functions of the skin Protection: Figure 2. On the limbs and trunk they tend to run circumferentially. Near flexures these lines are parallel to the skin crease. Wounds can be classified in terms of: Surgical procedures and accidental injuries may be classified according to the risk of wound contamination: Epithelial cells including those from any residual skin appendages such as sweat or sebaceous glands and hair follicles proliferate and migrate across the remaining dermal collagen.

Examples of superficial wounds: Superficial burn Graze Split-skin graft donor site Deep wounds Deep wounds involve layers deep to the dermis and heal with the migration of fibroblasts from perivascular tissue and formation of granulation tissue and subsequent true scar formation. Wounds are categorised as follows: Incised wounds: Although the skin may be intact.

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This occurs when. If a deep wound is not closed with good tissue approximation. Depth of wound Superficial wounds Superficial wounds involve only the epidermis and dermis and heal without formation of granulation tissue and true scar formation. It is usually associated with adjacent soft-tissue damage. Mechanism of wounding The mechanism of wounding often results in characteristic damage to the skin and deeper tissues.

Negative pressure dressings eg Vac can facilitate secondary intention healing when large wound defects are present Wounds that may be left to heal by secondary intention: Extensive loss of epithelium Extensive contamination Extensive tissue damage Extensive oedema leading to inability to close Wound reopened eg infection. The wound usually heals by rapid epithelialisation and formation of minimal granulation tissue and subsequent scar tissue.

This inevitably takes longer. Scar quality and cosmetic results are poor. The principles of wound management are concerned with providing an optimum environment to facilitate wound healing.

The wound is left open and allowed to heal from the deep aspects of the wound by a combination of granulation. There are three ways in which wound healing can take place: First primary intention Second secondary intention Third tertiary intention First primary intention This typically occurs in uncontaminated wounds with minimal tissue loss and when the wound edges can easily be approximated with sutures.

This may well follow a period of healing by secondary intention. Wound healing consists of three phases: Acute inflammatory phase see Chapter 4. The inflammatory phase Tissue damage starts a typical acute inflammatory reaction by damage to cells and blood vessels. All surgeons deal with wounds and it is essential to understand fully the exact pathophysiological mechanisms involved in wound healing.

Epithelial cells: The aims of wound healing are a rapid restoration of tissue continuity and a rapid return to normal function. The inflammatory phase of wound healing involves: The cross-linkage of collagen fibrils by formation of covalent bonds aided by the action of vitamin C increases the tensile strength of the scar.

It has a characteristic pinkish.

Multiple molecules orient to form a fibril. It consists of a rich network of capillary vessels and a heterogeneous population of cells fibroblasts. Endothelial cells Figure 2. In addition the wound contracts due to the action of myofibroblasts. Superficial skin wounds require minimal support and so can be closed with a quickly absorbable suture material or by interrupted sutures or staples that can be removed within days.

Nervous tissue possesses very limited regenerative capacity — partial function may be regained through slow neuronal growth in peripheral nerve injuries. Closure is therefore performed with either loop nylon that will persist in the wound. Inflammatory cells. Surgery performed on the fetus in utero leaves no scarring at all because it occurs by regeneration.

Choice of wound closure materials should reflect this. Blood lost into the wound clots into a fibrin meshwork the scab. Bowel and muscle regain near-full strength within 1 month and skin takes up to 6 months. After injury to the skin. Healing rates are quickest early in life. Skin Skin consists of two layers — the keratinised stratified epidermis and the connective tissue of the dermis. The tissue types and thickness involved in the scar will determine the length of time needed to regain strength.

Abdominal incisions through muscle layers will take many weeks to regain their strength. Neutrophils release cytokines.

Strength tends to increase very quickly over the first 7—10 days. Some tissues possess the ability to regenerate their specialised cells after injury. A new stratified epidermis with underlying basal lamina is then re-established. Recovery occurs through regeneration of the axons which grow along the existing preserved framework of the nerve.

The epithelial layer heals within 48 hours if the edges of the wound are accurately apposed. Regeneration requires time and may take weeks or months. In order of increasing degree of injury: Neuropraxia I: Accurate apposition of nerve ends Healthy surrounding tissue No tension Minimal dissection There are many variations of nerve injury. There is a reduction or block in conduction of the impulse down a segment of the nerve fibre.

A common classification was described by Seddon. It ranges in severity.. Neuropraxia I This is the mildest form of nerve injury. It is a more serious injury than neuropraxia.. Most neurotmetic injuries do not produce gross loss of continuity of the nerve but rather internal disruption of the architecture of the nerve sufficient.

Motor function often suffers greater impairment than sensory function. This may be caused by local biochemical abnormalities. ECM and basal lamina. There is a temporary loss of function that is reversible within hours to months of the injury average 6—8 weeks.

Wallerian degeneration occurs and there is a degree of retrograde proximal degeneration of the remaining axon. Axonotmesis II This is the loss of the relative continuity of the axon and its covering of myelin with preservation of the connective tissue framework of the nerve epineurium and perineurium.

IV and V This is the loss of continuity of both axons and nerve structural connective tissue. Protease secretion by the keratinocytes allows them to migrate through the fibrin mesh of the clot and the cut epidermal edges to move forward to cover the denuded wound surface. Neurotmesis III. Epidermal appendages eg sweat glands and hair follicles do not regenerate. Nerve injury and repair In a nutshell.

The other muscular layers of the bowel undergo the general phases of inflammation. After uncomplicated surgery to the gastrointestinal GI tract. Minor disruption to the mucosa is thought to be repaired by a process separate from proliferation. The intestinal mucosa is a sheet of epithelial cells that undergoes rapid turnover and proliferation.

Bowel The layers of the bowel involved in the anastomosis heal at different rates. Scarring may eventually contract. This causes intraneural scarring and regenerating axons may re-enter the sheaths incorrectly. It may sustain injury as a result of trauma from luminal contents or surgery. This may be associated with perineural haematoma or displacement of the nerve ends.

In grade V injuries the endoneurium. In organs in which the cells are terminally differentiated. In grade III injuries. Optimal healing requires good surgical technique and apposition of the layers. Anastomotic healing results in the formation of collagenous scar tissue. Solid organs Solid organs either heal by regeneration through a process of cell proliferation or by hypertrophy of existing cells. In grade IV injuries. There is a complete loss of motor.

Injury to the mucosa resulting in breaches of the epithelial layer is thought to render patients susceptible to bacterial translocation and systemic sepsis syndromes.

If the nerve has been completely divided. Some organs heal by a combination of the two processes. Within this scar tissue there is a degree of regeneration of myocytes and blood vessels. This is obviously accompanied by complete loss of function. Heart and lung Cardiac tissue is commonly damaged by ischaemia and occasionally by trauma. Healing in the kidney predominantly occurs by scarring and fibrosis. The stimulation for regeneration is reduction in the liver mass to body mass ratio eg surgical resection or the loss of liver functional capacity eg hepatocyte necrosis by toxins or viruses.

The cytokine response lasts about a week and the infarcted myocardium is gradually replaced by scar tissue. Increases in size and weight of the residual splenic tissue have been recognised after partial splenectomy eg for trauma. The inflammatory response is particularly important in the healing of cardiac tissue and is instigated by release of cytokines such as TNF- or IL-6 from the damaged myocardium.

The stimulus for hepatocyte proliferation is thought to be tumour necrosis factor TNF and the interleukin 6 IL-6 family of cytokines. About 24 hours after the hepatocytes start to proliferate.

Spleen Splenic regeneration is controversial. These cytokines have been implicated in the regulation of myocyte survival or apoptosis. This occurs initially in the areas surrounding the portal triads and then extends to the pericentral areas after 48 hours. Non-regenerative tissues Non-regenerative tissues.

Regeneration is achieved by proliferation of all the components of the mature organ — hepatocytes. Kidney The cells of the kidney are highly specialised. Liver The liver has remarkable regenerative capacity. Eventually the cell types restructure into functional lobules over 7—10 days. Wound healing is affected by: Heavily contaminated wounds or the abdominal cavity should be washed with copious amounts of warmed saline until clean. The same risk factors predispose to: Failure of wound healing Wound dehiscence Incisional herniation Wound dehiscence is the partial or total disruption of any or all layers of the surgical wound.

Ensure good delivery of blood and oxygen to the wound and be aware of the importance of good hydration and respiratory function. Sutures that are tied very tightly will cause tissue hypoxia. Patient nutrition is also very important and critically ill patients may require support via either nasogastric NG feeding or parenteral nutrition. Careful aseptic technique should be used. Avoid tension on the wound.

Management involves resuscitation. Under these circumstances. On occasions the patient may be in such a poor condition eg be elderly. Debride devitalised tissues and handle other tissues with care to prevent tissue necrosis. Without hydroxyproline. Minimisation of scarring Use lines of skin tension or hide the scar in naturally occurring lines including: Symptoms include visible protrusion of the hernia during episodes of raised intra-abdominal pressure and discomfort.

If too little fibrous tissue is laid down. It is usually many months. The final appearance of a scar depends on: As fibrous tissue is laid down. They occur at sites of partial wound failure or dehiscence. Further details on incisional hernias and methods of repair are covered in the Abdominal Surgery chapter of Book 2.

Incisional hernias usually correspond to a wide defect in the abdominal wall and so often do not incarcerate. Risk factors for incisional hernia are therefore the same as those for dehiscence. Scars Hypertrophic scars Most wounds become red and hard for a while but after several months spontaneous maturation leads to a pale soft scar.

Contractures can be both prevented and treated by using a Z-plasty to break up the scar. Due to fibroblast overactivity in the proliferative phase. Occasionally this excessive scar tissue remains. They may lead to distortion of adjacent structures eg near the eye or limited flexibility in joints. They may also be caused by extravasation injuries. Failure to remove dirt or surgical marker pen may result in permanent tattooing of a scar. A scar may become tethered to underlying structures and puckered.

Other scars Other kinds of scarring may also occur. Scars can be revised by means of Z-plasty or by direct revision after about 18 months. Any unusual ulceration or appearance in a scar should be biopsied. Scars may be widened and stretched if there is movement in that region that puts tension on the suture line.

Scrubbing Skin preparation and draping Theatre design Skin preparation The choice of surgical scrub is to use either chlorhexidine gluconate-containing or povidone iodinecontaining solutions and for these to either be alcohol based or aqueous. Alcohol-based solutions were thought to be quicker acting. This flammability can be minimised by allowing the skin time to dry and also avoiding preparation of areas that have excessive body hair.

Current National Institute for Health and Clinical Excellence NICE guidelines show little difference in cover between chlorhexidine and iodine solutions and find alcoholic and aqueous solutions acceptable. There is no evidence that removing hair before surgery reduces the risk of SSIs. Minimise risk to patient Asepsis Theatre briefing Surgical checklist Minimise risk to staff Standard and specialist precautions Minimising risk to patient Standard aseptic techniques are used universally to minimise risk of surgical site infections SSIs.

Using scrub solution. Preoperative checklists should be performed before the induction of anaesthesia.

Theatre design Position Theatres ideally should be close to the surgical wards. These may vary from hospital to hospital but should incorporate several key elements based on the WHO Surgical Safety Checklist see Figure 2. All patients should have consent forms and the correct site marked where appropriate before being in the theatre complex.

Minimising risk to theatre staff Wear correct gloves of correct size. A correct site form may also be used. This provides an opportunity for potential problems to be addressed.

The World Health Organisation Surgical Safety Checklist The WHO Surgical Safety Checklist has been introduced internationally because evidence has shown that the use of a standardised checklist before surgery both reduces surgical errors such as wrong site surgery and improves morbidity and mortality by promoting communication among the surgical team.

This may be because the organ is difficult to access gastro-oesophageal junction. Plan your closure at the same time as the incision — if the incision is complicated it is valuable to mark lines perpendicular to the incision in ink before you begin. Remember when planning that you may wish to extend your incision if access proves difficult!

If it is considered that different incisions may give identical access. As a general rule. These lines then show how the edges should be brought together accurately for closure. The most common reason for a difficult operation is inadequate access. Needlestick injury is discussed further in Microbiology. The surgeon can affect only the last of these. Limited access in adults to pelvic or subdiaphragmatic structure.

Narrow linea alba below umbilicus. External oblique aponeurosis is cut in the line of the fibres. Upper flap is raised and rectus sheath incised 1 cm cephalic to the skin incision not extending lateral to the rectus.

Takes longer to make and close. For further discussion of thoracic incisions and closures see the Cardiothoracic Surgery chapter of Book 2. Can lead to infection in rectus sheath. Some vessels cross the midline. Internal oblique and transversus abdominis are split transversely in the line of the fibres.

Gives access to: Heart including aortic and mitral valves. Quick to make and close. The sternum is divided using a pneumatic reciprocating saw or a jiggly saw. Poor cosmetic result. This was the only effective vertical incision in the days when catgut was the only suture material available. Not extended easily. If wound is extended laterally too many intercostal nerves are severed.

Heals securely and cosmetically. Useful for intrahepatic surgery. Used rarely for oesophageal. Median sternotomy This common incision is used in a number of surgical disciplines and is the most frequently used approach to the heart. Cannot be extended caudally. Takes longer to make than midline incision. Less pain and fewer respiratory problems than with longitudinal midline incision but division of red muscle involves more blood loss than longitudinal incision.

Tends to divide iliohypogastric and ilioinguinal nerves. Used rarely for liver and biliary surgery on the right. More painful than transverse incisions. The patient is placed supine with the neck extended.

Excellent access to female genitalia for caesarean section and for bladder and prostate operations. Rectus is then divided longitudinally in the midline. It is a midline incision extending from 2 cm below the sternal notch to the xiphoid. Thoracic incisions A summary of the important features of these incisions is presented below. Beware of intercostal nerves. Relatively avascular. May be modified into a skin-crease horizontal cut. Can be extended easily. Good incision for cholecystectomy on the right and splenectomy on the left — but beware superior epigastric vessels.

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