INTRAOPERATIVE COMPLICATIONS1 9 The use of perioperative beta-blockade may circumvent this problem. Immediate management sh ould involve a systematic search for the under- lying cause. If hypertension persists, the alternative options include increasing the depth of anesthesia and/or analgesia and adminis tration of alpha-blockers, beta-blockers or vasodilators. Bradycardia may be defined as a heart rate of <60bpm. It is commonly seen during anesthesia , particularly in young healthy adults or where opioids are used as part of the anesthetic. Surgical procedures which increase vagal tone may also produce bradycardia, for example, c ervical dilatation, anal stretch, traction on extraocular muscles, and peritoneal traction. Treatment is reserved for clinically significant bradycardias where there is a reduction in cardiac output or where escape beats are seen on the ECG. Treatment options include antich olinergics such as glycopyrrolate and atropine. For refractory bradycardia with haemodynami c compro- mise, it may be necessary to use either an isoprenaline infusion or a temporary t ransvenous cardiac pacing wire. Causes of intraoperative hypotension Decreased preload (cid:142)(cid:3) Hypovolaemia Dehydration/inadequate replacement Hemorrhage Gastrointestinal losses Insensible or third space losses Embolism (t hrombus, gas, fat, air) Aorto \200\223caval compression Pericardial tamponade (cid:142)(cid:3) Obstructed venous return (cid:142)(cid:3) Increased intra-thoracic pressure Positive pressure ventilation Pneumothorax Decreased afterload (cid:142)(cid:3) Drugs Induction agents Volatile agents Antihypertensives Histamine release Anaphylaxis/hypersensi tivity reactions (cid:142)(cid:3) Anesthetic technique Spinal anesthesia Epidural anesthesia (cid:142)(cid:3) Sepsis Decreased contractility (cid:142)(cid:3) Drugs Anesthetic agents Beta-blockers Calcium antagonists (cid:142)(cid:3) Myocardial ischaemia (cid:142)(cid:3) Acidosis (cid:142)(cid:3) Arrhythmia s CHAPTER 1 Perioperative anesthetic care 10 Causes of intraoperative hypertension Patient factors (cid:142)(cid:3) Pre-existing hyperte nsion (cid:142)(cid:3) Raised intracranial pressure (cid:142)(cid:3) Pre-eclampsia (cid:142 )(cid:3) Rebound hypertension (cessation of therapy) (cid:142)(cid:3) Phaeochromocytoma (ci d:142)(cid:3) Thyroid storm Surgical factors (cid:142)(cid:3) Prolonged tourniquet time (ci d:142)(cid:3) Aortic-cross clamping (cid:142)(cid:3) Post-myocardial revascularisation (cid :142)(cid:3) Bladder distension Anesthetic factors (cid:142)(cid:3) Inadequate depth of ane sthesia (cid:142)(cid:3) Inadequate analgesia (cid:142)(cid:3) Hypoxaemia (cid:142)(cid:3) Hypercapnia (cid:142)(cid:3) Instrumentation of airway (cid:142)(cid:3) Hypothermia (cid:14 2)(cid:3) Malignant hyperthermia (cid:142)(cid:3) Hypervolaemia Tachycardia may be defined as a heart rate of >100bpm. It can occur as a normal physiologic al response to sympathetic stimulation or as part of a pathological process such as sepsis, burns, hyperthyroidism or malig- nant hyperthermia. Increased sympathetic tone can be exac erbated by hypoxaemia, hypercapnia, hypotension, hypovolaemia and inadequate anesthesia/ana lgesia. Treatment involves correction of the underlying cause. Pharmacological intervention may be required if persistent tachy- cardia produces myocardial ischaemia. Arrhythmias occur frequently in the intraoperative period. They can be precipitated by the following: (cid:142)(cid:3) Hypoxaemia (cid:142)(cid:3) Hypercapnia (cid:142)(cid:3) Hypo/h yperkalaemia (cid:142)(cid:3) Myocardial ischaemia (cid:142)(cid:3) Surgical stimulation an d light anesthesia (cid:142)(cid:3) Deep inhalational anesthesia, particularly halothane (c id:142)(cid:3) Central venous cannulation (cid:142)(cid:3) Mediastinal manipulation (cid:14 2)(cid:3) Chronotropic drugs, particularly epinephrine. INTRAOPERATIVE COMPLICATIONS1 11 General management (cid:142)(cid:3) Correct the cause (hypoxia, hypercarbia, electrolyte im balance, and acidosis). (cid:142)(cid:3) Inform the surgeon to stop the surgery as reflex bradycardia can occur dur ing various procedures such as eye surgery, mesenteric traction, anal stretch, and laparosc opic procedures. (cid:142)(cid:3) Correct the hypotension. Specific management Aggressive management is requ ired in the presence of haemodynamic instability. Specific treatment of various arrhythmias is described below. Supraventricular arrhythmias Atrial fibrillation. ECG shows loss of P waves with complete i rregularity of the QRS complex. Because atrial contraction contributes up to 30% of the nor mal ventricular filling, the onset of AF often produces a marked fall in cardiac output. Treatment (cid:142)(cid:3) Amiodarone to slow down the ventricular rate and chemically cardiovert. (cid:142)(cid:3) Digoxin to slow ventricular rate. (cid:142)(cid:3) Flecainide to restore s inus rhythm (but caution with LV dysfunction). (cid:142)(cid:3) Synchronized DC cardioversi on in event of haemodynamic compromise. Atrial flutter is seen in the intraoperative period as a paroxysmal ar- rhythmia precipitat ed by anesthesia and surgery in a susceptible individual. ECG shows the classical \200\230 saw-tooth \200\231 pattern of flutter waves. Treatment (cid:142)(cid:3) Synchronized DC shock in an anesthetized patient with any degree of cardiovascular compromise is the first-line treatment. (cid:142)(cid:3) Digoxin or amiodaro ne infusion would be an alternative. Junctional/AV nodal tachycardias. ECG shows a narrow c omplex tachy- cardia with ventricular rate of 150 \200\223200/minute. A broad complex patte rn may be seen if there is antegrade conduction down an accessory pathway. Treatment (cid:142)(cid:3) Synchronized DC shock in a haemodynamically compromised patient. (cid:142)(cid:3) Carotid sinus massage or vagal maneuvers may slow the rate to reveal the underlying rhythm. (cid:142)(cid:3) Adenosine slows atrioventricular conduction and is particularly useful for terminating the re-entry tachycardia of Wolff \200\223Parkinson \200\223White syndrome. (cid:142)(cid:3) Verapamil, beta-blockers or amiodarone may improve rate control or convert to sinus rhythm. Ventricular arrhythmias Ventricular tachycardia. The ECG shows a broad complex tachycardia with capture and fusion beats. CHAPTER 1 Perioperative anesthetic care 12 Treatment (cid:142)(cid:3) Synchronized DC shock is the first-line treatment of VT with cardiovascular compromise. Synchronization is not required if the VT is very rapid or the p atient is pulseless. (cid:142)(cid:3) Amiodarone is the first line pharmacological agent. Ventricular fibrillation There is chaotic ventricular contraction with no identifiable QRS complexes on ECG. Treatment This should be promptly managed with DC cardioversion according to the European R esuscitation Council guidelines. Myocardial ischaemia occurs when myocardial oxygen demand exceeds supply. Oxygen supply to the myocardium is determined by coronary blood flow and oxygen content. Demand is determine d by heart rate, contractility and wall tension. Tachycardia is the most important deter- m inant of the supply/demand ratio because it causes a reduction in diastolic coronary fillin g, with a simultanous increase in myocardial work. Patients most at risk perioperatively ar e those with a recent MI, poorly controlled angina, decompensated heart failure or severe v alvular disease. Monitoring susceptible patients with a V5 ECG electrode and with continuou s ST segment analysis will improve ischaemia detection rates. Intraoperative management sho uld be geared towards ensuring adequate arterial oxygenation, maintaining normocapnia, norm otension, and avoidance of tachycardia whilst ensuring adequate depth of anaesthe- sia and effective analgesia. The use of glyceryl trinitrate as a coronary vasodilator may be necess ary if ischaemic changes persist. Respiratory complications Hypoxaemia can be defined as an arterial oxygen tension of <8kPa and causes specific to the intraoperative period are: Equipment problems (cid:142)(cid:3) Oxygen supply failure (cid:142)(cid:3) Delivery of a hy poxic mixture (cid:142)(cid:3) Obstruction or leak in anesthetic circuit (cid:142)(cid:3) D isconnection (cid:142)(cid:3) Ventilator failure (cid:142)(cid:3) Misplaced or obstructed e ndotracheal tube. Patient factors (cid:142)(cid:3) Hypoventilation in a spontaneously breat hing patient (cid:142)(cid:3) Increased airway resistance (bronchospasm, laryngospasm, anap hylaxis) (cid:142)(cid:3) Aspiration of gastric contents (cid:142)(cid:3) Atelectasis (cid: 142)(cid:3) Pneumothorax (cid:142)(cid:3) Pulmonary oedema (cid:142)(cid:3) Embolus (cid:14 2)(cid:3) Low cardiac output state (cid:142)(cid:3) Increased oxygen demand (sepsis, malign ant hyperthermia). INTRAOPERATIVE COMPLICATIONS1 13 If hypoxaemia is detected, a systematic ABC approach should be adopted. Delivery of 100% ox ygen (confirmed by oxygen analysis) is the first priority. Integrity of the breathing syste m should be confirmed by manual inflation of the lungs and checking for bilateral breath so unds and chest movement. The position and patency of the endotracheal tube should be confir med. A search for clinical causes should then ensue with early exclusion of pneumothorax. S ubsequent treatment is that of the underlying pathology. Laryngospasm is a reflex, prolonged closure of the glottis by adduction of the vocal cords. It usually occurs in response to airway manipulation in the context of light anesthesia. H owever, it may also occur in response to intense surgical stimulation such as incision and drainage of an abscess, peritoneal retraction, anal stretch or cervical dilatation. It occu rs more commonly in smokers and those with recent upper respiratory tract infec- tions beca use of increased airway reactivity. It may lead to complete or partial airway obstruction w ith resulting hypoxaemia and hypoventilation. Management should include assessment of ABC followed by: (cid:142)(cid:3) Cessation of the provoking stimulus (cid:142)(cid:3) Administration of 100% oxygen (cid:142)(cid:3) Increase in depth of anesthesia by intravenous route if necessary (cid:142)(cid:3) Laryngeal muscle relaxation with suxemethonium followed by ventilation with 100% and tracheal intubation if required. Bronchospasm is an acute bronchoconstriction causing increased airway resistance, wheeze, a nd a prolonged expiratory phase of respiration. Susceptibility to bronchospasm during the i ntraoperative period is increased in smokers, asthmatics, and those with chronic obstructiv e pulmonary disease, a recent respiratory tract infection, or an atopic tendency. Precipitating factors include: (cid:142)(cid:3) Surgical stimulation or airway manipulation during light anesthesia (cid:142)(cid:3) Stimulation of the carina or bronchi by the trach eal tube (cid:142)(cid:3) Pharyngeal, laryngeal, or bronchial secretions or blood (cid:142) (cid:3) Aspiration of gastric contents (cid:142)(cid:3) Anaphylactic reactions (cid:142)(ci d:3) Release of histamine (cid:142)(cid:3) Administration of beta-blockers. Management aims are to maintain oxygenation, treat the underlying cause and reduce bronchoconstriction. 10 0% oxygen should be administered and the inspired concentration of volatile anesthetic agen t increased. The position and patency of the endotracheal tube should be checked. Bronchodi latation can be achieved by intravenous or nebulised salbuta- mol or by an intravenous infu sion of aminophylline. Epinephrine is reserved for life-threatening emergencies. Pneumothorax during the intraoperative period is rare but potentially life threatening. Pat ients with recent chest trauma, rib fractures, asthma, and chronic lung disease with bullae are most at risk. Iatrogenic causes include central venous cannulation, brachial plexus bl ock, intercostal nerve block, tracheostomy, thoracic surgery, and barotrauma. Clinical CHAPTER 1 Perioperative anesthetic care 14 signs include tachycardia, hypotension, hypoxaemia and high airway pres- sures. During anes thesia, nitrous oxide can diffuse into air-filled spaces causing a pneumothorax to expand. Positive pressure ventilation also contributes to a rapid increase in size. If the pneumoth orax is under tension, impaired venous return and cardiac output can precipitate cardiac ar rest. Immediate management involves the ABC approach, ces- sation of nitrous oxide, deliver y of 100% oxygen, and insertion of an intercostal drain. If the pneumothorax is under tensi on needle thora- cocentesis should be performed prior to sitting an intercostal drain. Embolism describes the entry of air/gas/thrombus/fat/amniotic fluid into the circulation us ually via the venous route. This causes an obstruction to right ventricular outflow, reduci ng cardiac output and arterial blood pressure. Risk factors for emboli include: Anesthetic factors (cid:142)(cid:3) Hypovolaemia (cid:142) (cid:3) Open central vascular access (cid:142)(cid:3) Pressurized infusions (cid:142)(cid:3 ) Prolonged use of a tourniquet (cid:142)(cid:3) Operation site higher than heart. Surgical factors (cid:142)(cid:3) Multiple trauma (cid:142)(cid:3) Long bone surgery especially int ramedullary nailing (cid:142)(cid:3) Hip and spinal surgery (cid:142)(cid:3) Laparoscopic p rocedures (cid:142)(cid:3) Neck surgery (cid:142)(cid:3) Vascular surgery (cid:142)(cid:3) Middle ear procedures. Diagnosis is often difficult in the anesthetized patient and relies upon a high degree of clinical suspicion in the context of tachycardia, hypoxae- mia, and a fall in end-tidal carbon dioxide concentration. In the case of a large embolism, pulseless ness and altered cardiac electrical activity may occur. Management (cid:142)(cid:3) Follow the ABC approach. (cid:142)(cid:3) Maintain the airway, with 100% oxygen. (cid:142)(cid:3) Support the circulation with volume expansion and inotro pes, to maintain the mean arterial pressure. (cid:142)(cid:3) In the event of gas/air embolism, subsequent management is aimed specifica lly at preventing further entry into the circulation. This may involve flooding the operati ve site with saline and covering it with wet gauze, compressing the major drainage vessels, lowering the operation site below the level of the heart or decompressing any gas-pressuri zed cavity. (cid:142)(cid:3) Gas can be aspirated from the right heart if a central venous catheter is in situ. Siting a central line for aspiration of gas is usually impractical, time consuming and not recommended. INTRAOPERATIVE COMPLICATIONS1 15 Aspiration of gastric contents is a potential problem in all anesthetized or unconscious pa tients as upper airway reflexes are depressed and lower oesophageal sphincter tone decrease d. Factors predisposing to aspiration include: (cid:142)(cid:3) Full stomach (cid:142)(cid:3) Known gastro-oesophageal reflux or hiatus hernia (cid:142)(cid:3) Raised intragastric press ure (gastrointestinal obstruction, pregnancy, laparoscopic surgery) (cid:142)(cid:3) Recent trauma (cid:142)(cid:3) Pain (cid:142)(cid:3) Opioid analgesia (cid :142)(cid:3) Diabetes mellitus (cid:142)(cid:3) Topically anesthetized airway Management of intraoperative aspiration should be aimed at minimizing further regurgitation with clearan ce of gastric aspirate and subsequent airway protection. The patient should be placed in a left lateral head-down position, cricoid pressure applied and the trachea intubated. Gastri c aspirate should be cleared by suctioning prior to initiation of positive pressure ventila tion. Bronchoscopy bronchial lavage may be necessary to clear any remaining debris. If h ypoxaemia ensues, ventilation with application of PEEP and delivery of high inspired oxygen concen- trations may be required. Chest X-ray and blood gas analysis are mandatory. Respir atory support may need to be continued in ICU. Adverse drug reactions Anaphylaxis is an IgE mediated hypersensitivity reaction to an antig en which results in mast cell and basophil degranulation with release of histamine and sero tonin. The incidence of anaphylaxis in anesthetic practice is in the order of 1:10 000. It is more common in females and in patients with a history of allergy. 90% of reactions occur immediately after induction of anesthesia. Precipitating drugs include: (cid:142)(cid:3) Muscle relaxants, particularly suxemethonium (cid:142)(cid:3) Intravenous induction agents, most commonly thiopentone (cid:142)(cid:3) O pioid analgesics (cid:142)(cid:3) Local anesthetics (cid:142)(cid:3) Colloid solutions (cid :142)(cid:3) Antibiotics especially penicillins (cid:142)(cid:3) Radio contrast media (cid: 142)(cid:3) Latex. Clinical features may vary from mild cutaneous manifestations such as ur ticaria and erythema to cardiovascular collapse and cardiac arrest. Management (cid:142)(cid:3) Stop administration of offending drug. (cid:142)(cid:3) Maintai n the airway and administer 100% oxygen. CHAPTER 1 Perioperative anesthetic care 16 (cid:142)(cid:3) Administer intravenous epinephrine (0.5 \200\2231.0 ml 1:10 000) if the pa tient is haemodynamically compromised. If the intramuscular route is used, 0.5 \200\2231.0 ml of 1:1000 epinephrine should be given initially and repeated every 10 minutes until impr ovement is established. Epinephrine produces peripheral vasoconstriction, increased cardiac output, bronchodilatation and stabilization of mast cells. (cid:142)(cid:3) Expand the intravascular volume with colloids or crystalloids. (cid:142)(c id:3) Administration of corticosteroids, antihistamines and bronchodilators (if required) is the second line treatment. (cid:142)(cid:3) Correct severe acidosis with sodium bicarbonate and continue epinephrine by infusion. (cid:142)(cid:3) Take a blood sample 1 hour after the start of the reaction and a further sample at 24 hours for tryptase estimation. (cid:142)(cid:3) Refer the patient for intradermal skin prick tests to identify the causative agent. (cid:142)(cid:3) Advise the patient to carry some form of hazard alert and a yellow card sh ould be submitted to the Committee on Safety of Medicines. Malignant hyperthermia is a rare genetic disorder with autosomal domi- nant inheritance characterized by a marked increase in skeletal muscle metabolism. Contact with a trigger agent can precipitate abnormal cal- c ium release from the sarcoplasmic reticulum which leads to sustained muscle contraction. Th is produces a hypermetabolic state with increased carbon dioxide production, hyperthermia, metabolic acidosis, muscle breakdown, and hyperkalaemia. All inhalational anesthetic agents and suxemethonium can trigger this response in a susceptible individual. Management involves: (cid:142)(cid:3) Discontinuation of potential trigger agents (cid:142) (cid:3) Use of a vapor-free anesthetic machine and circuit (cid:142)(cid:3) Administration of dantrolene 1mg/kg (cid:142)(cid:3) Supportive treatment (cid:142)(cid:3) Hyperventilation with 100% oxygen (cid:142)(cid:3) Correction of acidosis and hyperkalaemia (cid:142)(cid:3) Active cooling (cid:142)(cid:3) Treatment of any arrhyth mias (cid:142)(cid:3) Diuretic therapy to prevent renal damage by myoglobin (cid:142)(cid:3 ) Invasive monitoring on ICU. Mortality is in the order of 5%. All suspected cases and their first degree relatives should be referred to a specialist cen ter for screening. This usually involves subjecting them to a muscle biopsy specimen for co ntracture testing. This page intentionally left blank CHAPTER 1 Perioperative anesthetic care 18 Postoperative complications Various complications can occur in the postoperative period bec ause of the dysfunction of different systems, including respiratory, cardiac, central nerv- ous, gastrointestinal, hepatic, and renal. The patient should be nursed on a tipping troll ey, with 1:1 monitoring by trained recovery personnel until the patient is fully conscious. This section describes the diagnosis and manage- ment of common problems encountered in th e postoperative period. Hypoxia Fall in the arterial oxygen tension results in tissue hypox ia and can be diag- nosed by pulse oximetry. Immediate steps should be taken to improve the oxygenation before clinical signs of hypoxia (peripheral or central cyanosis) appear. Caus es include airway obstruction due to decreased pharyngeal muscle tone and falling back of t he tongue, residual effects of opioids, anesthetic agents or muscle relaxants, ventilation perfusion mismatch, basal atelectasis, lung collapse and pneumothorax. Pulse oximetry is un reli- able in the states of hypoperfusion, shock, and extreme vasoconstriction. Management (cid:142)(cid:3) Ensure that the airway is patent. (cid:142)(cid:3) Correct airw ay obstruction by simple maneuvers, such as head tilt, chin lift, or jaw thrust. (cid:142)(cid:3) Rule out the presence of foreign body (secretions, blood, or a fallen tooth) causing the airway obstruction. (cid:142)(cid:3) Administer 10 litres/minute of oxygen with a facemask. (cid:142)(cid:3) In troduce the Guedal \200\231s pharyngeal airway if the patient can tolerate and if the norma l maneuvers fail to remove the airway obstruction. (cid:142)(cid:3) Patients who are not breathing or are hypoventilating should be ventilated with bag and mask. Nausea and vomiting Predisposing factors (cid:142)(cid:3) Patient factors \200\224female pa tients, past history of PONV, presence of blood in stomach, presence of nasogastric tube. (cid:142)(cid:3) Surgical factors \200\224laparoscopic, middle ear, and abdominal surgery. (cid:142)(cid:3) Pharmacological factors \200\224opioids, nitrous oxide, inhalational agent s. (cid:142)(cid:3) Physiological factors \200\224hypotension, hypoxia. Management (cid:142 )(cid:3) Prophylactic administration of antiemetic is indicated in high risk patients with one or more predisposing factors. Cyclizine 50mg or ondansetron 4mg can be in jected intravenously. (cid:142)(cid:3) In case of PONV treat hypotension as it can cause PONV. (cid:142)(cid:3) C yclizine should be used as the first line of treatment, failing which ondansetron can be given intravenously. Hypotension Causes (cid:142)(cid:3) Hypovolaemia (cid:142)(cid:3) Spinal or epidural anesth esia POSTOPERATIVE COMPLICATIONS1 19 (cid:142)(cid:3) Dysrhythmias (cid:142)(cid:3) Sepsis (cid:142)(cid:3) Myocardial infarctio n and left ventricular failure. Management (cid:142)(cid:3) Administer oxygen 10 litres/min ute by face mask. (cid:142)(cid:3) Ensure that blood volume status is optimized. (cid:142)( cid:3) Administer ephedrine 3 \200\2236mg intravenously. (cid:142)(cid:3) Treat the dysrhyt hmia. (cid:142)(cid:3) Restrict fluid administration in patients with LVF and MI. Start appropriate medical management. (cid:142)(cid:3) Transfer the patients with sepsis or cardiogenic problems to HDU or CCU for subsequent management. Hypertension Inadequate analgesia is the commonest cause of hypertension in the postoperati ve period. Antihypertensive medication should only be administered once adequate pain relie f is provided to the patient. Sore throat Use of laryngeal mask airway, laryngoscopy, and intubation are all associated w ith high incidence if sore throat. Patients recover from this complication within 24 \200 \22348 hours. Practical procedures Various practical procedures are required in patients requiring critic al care and anesthesia for various surgical operations. Universal precau- tions should be t aken against cross-infection, while performing these procedures, where contact with blood o r body fluids is likely. Vascular access (cid:142)(cid:3) Peripheral venous Airway access (cid:142)(cid:3) Oropharyngeal and cannulation nasopharyngeal airway insertion (cid:142)(cid:3) Laryngeal mask airway insertion (cid:142)( cid:3) Orotracheal intubation (cid:142)(cid:3) Cricothyroidotomy (cid:142)(cid:3) Percutane ous tracheostomy (cid:142)(cid:3) Arterial cannulation (cid:142)(cid:3) Central venous cannulation (cid:142) (cid:3) Pulmonary artery catheterisation Peripheral venous cannulation Choose appropriate size of cannula depending upon the age of the patient: 24 gauge cannula in neonates, 22 gauge in small children, and 18 and 14 gauge in adults. The size of the cannula also depends on the rate of administration of the fluid. In small children topical anesthesia with EMLA or Ametop cream should be applied, whereas in adult patients a small bleb can be raised by an intradermal injection of 1% lignocaine t o alleviate the pain of venepunc- ture. Peripheral venous cannulation assembly consists of a cannula, mounted on the needle, an injection port, and a flash chamber (Fig. 1.1). CHAPTER 1 Perioperative anesthetic care 20 Injection port Flash chamber Needle and cannula Fig. 1.1 Cannula for peripheral venous cannulation Flow switch Flash chamber Fig. 1.2 Cannula with flow switch (cid:142)(cid:3) Clean the skin with an alcoholic antiseptic solution or swab. (cid:142)(ci d:3) Insert the cannula after stretching the skin in the non-dominant arm. (cid:142)(cid:3) Puncture the skin at 15 angle and advance until blood is seen in the flash chamber. (cid:142)(cid:3) Make the cannula nearly parallel to the skin. (cid:142)(cid:3) Advance a l ittle bit further so that both the tip of the needle and the cannula are in the lumen of the vein. (cid:142)(cid:3) Hold the needle and thread the cannula into the vein. (cid:142)(cid:3) Pre ss the skin above tip of the cannula while withdrawing the needle, so that there is no spill over of blood and occlude the proximal end of the cannula with a bung. (cid:142)(cid:3) Discard the sharp in a disposable bin-box. Arterial cannulation Arterial cannulation is undertaken to monitor continuous blood pressur e in critically ill patients and those requiring major surgery. A cannula can also be used where the repeated blood sample is required for arterial blood gas analysis. The most frequ ent site of arterial cannulation is the radial artery, although the femoral, brachial, and dorsalis pedis artery can also be cannulated. Allen \200\231s test should be performed to a ssess the adequacy of collateral circulation. The patient is asked to clench the fist very tightly POSTOPERATIVE COMPLICATIONS1 21 while the radial and the ulnar arteries are compressed tightly to exsan- guinate the palm. The patient is asked to open the fist and pressure on the ulnar artery is released. Collate ral flow via the radial artery is ade- quate if the blanched palm of the hand becomes pink in less than six seconds. Technique The arm should be rested on a side support and a small, rolled sheet placed under neath the back of the wrist and the hand dorsiflexed. Clean the site with antiseptic soluti on. The site of puncture should be infiltrated with 1% lignocaine, using a 24 gauge needle. Usually a 20 gauge Teflon or polyethylene cannula with a flow switch (Fig. 1.2) is inserte d at an angle of 30 to the skin, while palpating the radial artery, proximal to the point of insertion. As soon as the blood is seen in the flash chamber, the angle should be lower ed to 15 and the assembly is pushed a little further so that both the needle and cannula are in the lumen of the artery. At this stage, the needle should be held firmly between the thumb and the index finger, while pushing the cannula into the artery. Withdraw the needle while pressing the tip of the cannula to avoid spilling of the blood and press the flow sw itch on after the needle is completely out. Complica- tions include infection, thrombosis, and ischaemia. Central venous cannulation Central venous pressure (CVP) can be monitored by placing the ti p of the cannula in intrathoracic portion of the superior or inferior vena cava. CVP reflec ts the filling pressure of the right side of the heart. CVP monitoring is done commonly to monitor the volume status and to enable accurate fluid therapy in hypovolaemic patients, wi thout causing overload. Routes of central venous cannulation (cid:142)(cid:3) Antecubital vein in cubital fossa (ci d:142)(cid:3) External jugular vein (cid:142)(cid:3) Internal jugular vein (cid:142)(cid:3) Subclavian vein (cid:142)(cid:3) Femoral vein. The right internal jugular vein is cannulat ed most commonly because of its straight course, ease of insertion and reduced incidence of certain compli- cations, such as pneumothorax, as compared with the subclavian route. (cid :142)(cid:3) The patient should be positioned in Trendelenberg position with the head turned to the opposite side. (cid:142)(cid:3) A multiple lumen catheter is inserted into the internal jugular vein using Seldinger \200\231s technique. The catheter kit (Fig. 1.3) consists of a needle, J wire, d ilator sheath, and multilumen catheter. (cid:142)(cid:3) A needle connected with a saline filled syringe is inserted at 30 to the skin at the apex of the triangle formed by the sternal and clavicular heads of sternocleid omastoid and clavicle, using aseptic technique. (cid:142)(cid:3) Advance the needle caudal and laterally towards the ipsilateral nipple until venous blood is aspirated. Never advance the needle more than 2.5cm. (cid:142)(cid:3) The syringe is disconnected and J tipped wire inserted through the needle. CHAPTER 1 Perioperative anesthetic care 22 Fig. 1.3 Central venous catheter kit (cid:142)(cid:3) A CVP catheter is passed over the wire, after dilatation of puncture site, and wire is removed. (cid:142)(cid:3) A chest X-ray should be done to check the placement and to rule out pneumothorax. (cid:142)(cid:3) Central venous pressure can be measured by connecting the catheter to a pr essure transducer or a saline filled manometer calibrated to midaxillary line as the refere nce point. Complications Immediate (cid:142)(cid:3) Carotid artery puncture (cid:142)(cid:3) Dysrhythm ias (cid:142)(cid:3) Pneumothorax (cid:142)(cid:3) Air embolism (cid:142)(cid:3) Malpositio ning. Delayed (cid:142)(cid:3) Thrombosis (cid:142)(cid:3) Sepsis. Pulmonary artery catheterisation (PAC) This procedure is performed to measure pulmonary cap illary wedge pressure which approximates the left atrial pressure in the presence of normal pulmonary vascular resistance. PAC can be used to monitor cardiac output, mixed venous oxy gen saturation, systemic and pulmonary vascular resistance. The balloon tipped, 110cm long catheter (Fig. 1.4) is introduced through the introducer sheath placed in the internal jugu lar vein using Seldinger \200\231s technique (refer to CVP cannulation). The distal lumen i s connected to a pressure transducer through a saline filled column. The balloon is inflate d with 1.5ml of air after tip of catheter is in POSTOPERATIVE COMPLICATIONS1 23 Fig. 1.4 Balloon tipped catheter right atrium. The catheter is advanced and location of the tip of the catheter is guided by the pressure waveforms (Fig. 1.5). The catheter should not be advanced once the wedge trac e is obtained. Deflation of the balloon should result in a pulmonary arterial trace. Complications Immediate (cid:142)(cid:3) Arterial puncture (cid:142)(cid:3) Haematoma (cid: 142)(cid:3) Pneumothorax (cid:142)(cid:3) Dysrhythmias (cid:142)(cid:3) Air embolism (cid:1 42)(cid:3) Knotting (cid:142)(cid:3) Malpositioning Delayed (cid:142)(cid:3) Infection (cid :142)(cid:3) Thrombosis (cid:142)(cid:3) Pulmonary hemorrhage, infarction. Indications (cid :142)(cid:3) ARDS (cid:142)(cid:3) Severe sepsis (cid:142)(cid:3) Titration of inotropes in patients with poor cardiac function (cid:142)(cid:3) Major trauma and operations associate d with major fluid shifts. Oropharyngeal airway insertion Guedal \200\231s airway should be inserted in patients with airway obstruction if simple maneuvers like chin lift and jaw thrust fail. A conscious pati ent will not tolerate this airway. CHAPTER 1 Perioperative anesthetic care 24 Pulmonary arterial pressure Pulmonary wedge pressure 30 20 10 0 30 20 10 0 30 20 10 0 Central venous pressure Pressure waveforms encountered during insertion of pulmonary artery catheter (from Kalia an d Webster, 2001) 30 20 10 0 Right ventricular pressure Fig. 1.5 Placement of pulmonary artery catheter showing related pressure valves Technique (cid:142)(cid:3) Choose the appropriate size airway (Fig. 1.6) by placing the air way between tip of tragus and angle of mouth. A large airway can itself cause the obstructi on whereas a smaller than ideal airway will not be able to remove the obstruction. (cid:142)(cid:3) Open the mouth, depress the tongue, and slide the airway posteriorly betwe en tongue and hard palate, with concavity facing the front, until the flange is positioned and rests between lips and the teeth. (cid:142)(cid:3) In case of difficulty the airway can be inserted with concavity facing the hard palate. At the first point of resistance the airway should be rotated by 180 and pus hed downwards gently till the flange rests between lips and teeth. Avoid this technique in small children as it can cause trauma to soft palate. Nasopharyngeal airway insertion Patients with intact pharyngeal reflexes tolerate nasophary ngeal airways better than oropharyngeal airways. Technique (cid:142)(cid:3) Check the paten cy of nostrils and choose the nostril with greater patency. (cid:142)(cid:3) Lubricate the nasopharyngeal airway with jelly and insert in downward and posterior direction till the flange rests in front of the nostril. POSTOPERATIVE COMPLICATIONS1 25 Fig. 1.6 Guedal \200\231s airways Laryngeal mask airway (LMA) It is introduced through the oral cavity after induction of ane sthesia. The laryngeal mask (Fig. 1.7) rests in front of the laryngeal inlet. It provides h ands-free clear airway and obviates the need for tracheal intubation, thereby avoiding all the complications of intubation. It offers no protec- tion from aspiration of gastric conte nts. Indications (cid:142)(cid:3) Provision of a clear airway overcoming the need to hold a facemask. (cid:142)(cid:3) Avoidance of tracheal intubation in a spontaneously breathing p atient. (cid:142)(cid:3) Airway maintenance in known or suspected cases of difficult intuba tion. (cid:142)(cid:3) Emergency management of failed intubation. (cid:142)(cid:3) Provisio n of a temporary airway during cardiopulmonary resuscitation. The LMA does not protect agai nst aspiration of gastric contents. In pa- tients with a full stomach, delayed gastric empt ying, gastro-oesophageal reflux, or a hiatus hernia, the use of a LMA is contraindicated. T echnique (cid:142)(cid:3) Adequate depth of anesthesia/suppression of airway reflexes shoul d be established. (cid:142)(cid:3) Extend the patient \200\231s head and open mouth. It may be necessary to hold down the lower jaw. (cid:142)(cid:3) Introduce the LMA into the oro-pharynx using a gloved finger. It is gently advanced along the hard palate until the tip of the cuff reaches the posterior phary ngeal wall. Advance it distally into the laryngo- pharynx until the cuff sits posterior to the larynx. (cid:142)(cid:3) When correctly positioned, inflate the cuff and the LMA is connected to a breathing system and secured. (cid:142)(cid:3) Confirm correct placement by manual inflation of the lungs or by observation of movement of a reservoir bag in spontaneously breath- ing patients. CHAPTER 1 Perioperative anesthetic care 26 Fig. 1.7 Laryngeal mask airway Orotracheal intubation A definitive airway requires placement of a cuffed tube in the trach ea. The tracheal tube (Fig. 1.8) is made of PVC and is radio-opaque. Most male patients req uire size 9 whereas female patients need size 8 tracheal tubes. Tracheal tube has a low pre ssure cuff designed to provide an airtight seal after inflation with air. Appropriate size and length of orotra- cheal tube in the children can be calculated by the formulas. Age Age Size = + 4.5mm Length = + 12cm 4 2 Technique (cid:142)(cid:3) Check the laryngoscope and ensure that cuff of the tracheal tube is not leaking. (cid:142)(cid:3) Induce the conscious patient with an appropriate induction agent and muscle relaxant should be used to facilitate intubation. (cid:142)(cid:3) Position the patient in \200\230sniffing the morning air position \200 \231 (flexion of neck by placing a 4 inch thick pillow under the occiput and extension at atlanto-occipital joint). Avoid manipulation of the neck in the patients with suspected cervical spine injury . (cid:142)(cid:3) Introduce the blade of the laryngoscope from right side of the mouth. Displace the tongue to the left by the flange of laryngoscope. (cid:142)(cid:3) Keep sliding the spatula of the blade on the tongue until the epiglottis is visualized. (cid:142)(cid:3) Tip of the blade should rest in the vallecula (junction of epiglottis and the base of tongue). Lift the laryngoscope in the direction of the handle. (cid:142)(cid:3) Identify the laryngeal inlet by the vocal cords and insert the tracheal tube gently into the trachea. Inflate the cuff of the tube with air, enough to prevent the audible leak of gasses on positive pressure ventilation. (cid:142)(cid:3) Confirm the place ment of the tube by auscultation and capnography. POSTOPERATIVE COMPLICATIONS1 27 Fig. 1.8 Endotracheal tube Indications for intubation (cid:142)(cid:3) Unconscious patient (cid:142)(cid:3) Risk of as piration (patient with full stomach) (cid:142)(cid:3) Mechanical ventilation (apnoea, intra thoracic surgery) (cid:142)(cid:3) Operations with difficult airway access (ENT, prone posi tion). Complications of intubation (cid:142)(cid:3) Trauma to face, lips, tongue, and teeth (cid:142)(cid:3) Hypertensive response (cid:142)(cid:3) Arrhythmias. Cricothyroidotomy Thi s procedure requires an opening in the cricothyroid membrane and the airway can be secured by placing the tube in the trachea through this opening. Cricothyroidotomy is a life-saving procedure in a patient with airway obstruction where airway access is impossible through t he oro- pharyngeal or nasopharyngeal route. Cricothyroidotomy can be per- formed with the h elp of a needle or a proper tube can be introduced through the membrane using Seldinger \200\231s technique. Technique (cid:142)(cid:3) Stabilize the cricothyroid membrane (extend s between thyroid and cricoid cartilage) between thumb and index finger and puncture with a 12 or 14 needle conne cted with a saline filled syringe. (cid:142)(cid:3) Advance the needle at 45 angle until air is aspirated freely. (cid:142)(cid:3) Connect the needle to an oxygen source. (cid:142) (cid:3) Occlusion of the hole in the connecting tubing causes inflation of the chest and oxygenation of the patient. Inflate for one second and deflate for four seconds. Elimination of carbon dioxide is inadequate with this CHAPTER 1 Perioperative anesthetic care 28 technique and formal tracheostomy should be done within 45 minutes of this procedure to est ablish normal ventilation otherwise the patient will become hypercapnic. (cid:142)(cid:3) Seldinger \200\231s technique consists of the introduction of a J tipped w ire through the needle once the tip of the needle is in the trachea. The needle is withdraw n and the dilator and cricothyroidotomy tube as- sembly is railroaded over the J wire. The dilator and J wire is with- drawn leaving the tube in the trachea. (cid:142)(cid:3) Confirm the placement of the tube by auscultation and capnography. Complic ations (cid:142)(cid:3) Haematoma (cid:142)(cid:3) Aspiration (cid:142)(cid:3) Perforation of posterior wall of trachea (cid:142)(cid:3) Hoarseness (cid:142)(cid:3) Hemorrhage (cid:1 42)(cid:3) Subglottic stenosis (cid:142)(cid:3) Surgical emphysema (cid:142)(cid:3) False p assage. Tracheostomy (see Chapter 15) Chapter 2 29 2 Theater procedures and prophylaxis