The Post anesthesia care unit [PACU] ppt

The Post anesthesia care unit [PACU] is designed and staffed to monitor and care for patients who are recovering from the immediate physiologic effects of anaesthesia and surgery.
PACU is well equipped to resuscitate patients who are unstable while providing a tranquil environment for the “recovery” and comfort of patients who are stable.

1. POST ANAESTHESIA CARE UNIT BY Dr. SHARATH KUMAR M.P MODERATOR- Dr PRASHANTH ASSOCIATE PROFESSOR DEPT OF ANAESTHESIOLOGY

2. INTRODUCTION The Post anaesthesia care unit [PACU] is designed and staffed to monitor and care for patients who are recovering from the immediate physiologic effects of anaesthesia and surgery. PACU is well equipped to resuscitate patients who are unstable while providing a tranquil environment for the “recovery” and comfort of patients who are stable.

3. ADMISSION TO THE PACU On arrival of a patient to the PACU, the anaesthesiologist provides the PACU nurse with patient’s details , medical condition, anaesthesia and surgery.

4. STANDARDS FOR POST ANAESTHESIA CARE All patients who have received General anaesthesia , regional anaesthesia or monitored anaesthesia care shall receive appropriate post anaesthesia management. A Patient transported to the PACU shall be accompanied by a member of the anaesthesia care team who is knowledgable about the patient’s condition.

5. 3. The patient shall be continually evaluated and treated during transport with monitoring and support appropriate to the patient’s condition. 4. The patient’s condition shall be evaluated continually in the PACU. Particular attention is given to monitoring oxygenation , ventilation , circulation and level of consciousness.

6. POST-OPERATIVE PHYSIOLOGIC CHANGES . Loss of Pharyngeal muscle tone – Causes can be from effects of A] Inhaled and i.v anaesthetics . B] Neuromuscular blocking drugs and opioids all contribute to the loss of pharyngeal tone in the patient In the PACU. Pharyngeal muscle activity is depressed during sleep and the resulting decrease in tone can further promote Airway obstruction.

7. Measures to overcome pharyngeal muscle tone. Opening the airway with the Jaw thrust Maneuvre or continuous positive airway pressure (CPAP) applied via a facemask can relieve the airway obstruction secondary to the loss of Pharyngeal tone. Support of the airway is needed until the patient has adequately recovered from the effects of drugs administered during anaesthesia and in some cases placement of oral or Nasal airway , Laryngeal mask airway , or ETT is required .

8. RESIDUAL NEUROMUSCULAR BLOCKADE . Residual neuromuscular blockade may not be evident on arrival in the PACU because the diaphragm recovers from neuromuscular blockade before the pharyngeal muscles do. A decline in train of four ratio TOF may not be appreciated until it reaches a value less than 0.4to 0.5 A Prospective study of over 18,000 patients who received intermediate-acting neuromuscular drugs and their matched cohorts showed that paralysis with inter-mediate acting neuromuscular blockade is associated with increased risk of postoperative complications.

9. FACTORS CONTRIBUTING TO PROLONGED NON-DEPOLARZING NEUROMUSCULAR BLOCKADE Drugs 1. Inhaled anaesthetic drugs 2.Local anaesthetics ( lidocaine) 3.Cardiac antiarrhythmics ( procainamide) 4. Antibiotics (polymyxins ,aminoglycosides, lincosamines,clindamycin ) Metronidazole.

10. Corticosteroids and Calcium channel blockers. Dantrolene METABOLIC AND PHYSIOLOGIC STATES Hypermagnesia Hypocalcemia Hypothermia Respiratory acidosis Hepatic or renal failure

11. In an awake patient clinical assessment of reversal of neuromuscular blockade is done by checking the :- Grip strength Tongue protrusion Ability to lift the legs off the bed , and ability to lift the head off the bed for a full 5 seconds. Of all these manuevers , the 5-second sustained head lift has been considered the standard, reflecting not only the motor strength, but more importantly , the patient’s ability to maintain and protect the airway.

12. Reversal can be achieved by : Warming the patient airway support , and correction of electrolyte abnormalities. Use of sugammadex resulted in return of TOF ratio of greater than 0.9 within 5 minutes in 85% of patients with no twitches on TOF stimulation.

13. LARYNGOSPASM Sudden spasm of vocal cords that completely occludes the laryngeal opening. It typically occurs in the transitional period when the patient is extubated. Although laryngospasm most likely occurs in the operating room at the time of tracheal extubation , but can also occur in patients in PACU who are asleep after General anaesthesia. Management – Jaw thrust manueuver with CPAP (up to 40 cm of water) If jaw thrust manuever fails, then skeletal muscle relaxation can be achieved with Succinylcholine 0.1 to 1.0 mg/kg intravenously Or 4mg /kg Succinylcholine intramuscularly can be given.

14. EDEMA OR HEMATOMA A irway edema is caused by surgical procedures of tongue, pharynx, neck , thyroidectomy , carotid endarterectomy and cervical spine procedures. So in these conditions there is extensive edema . Mask ventilation may not be possible in a patient with severe upper airway obstruction resulting from edema or hematoma. So in such conditions hematoma must be evacuated and clips or sutures released to decompress the airway. Emergency tracheostomy will be performed when there is too much fluid or blood that has infiltrated the tissues of pharyngeal wall.

15. OBSTRUCTIVE SLEEP APNEA Patients with Obstructive sleep apnea are particularly prone to airway obstruction and hence should not be extubated until they are fully awake and obey the commands. Patients with OSA are sensitive to benzodiazepines and opioids and it can result in airway obstruction in PACU. Hence opioids must be avoided.

16. POST-OPERATIVE HYPOXEMIA Atelectasis and alveolar hypoventilation are the most important causes of transient postoperative arterial hypoxemia in immediate post operative ward. Arterial hypoxemia secondary to hypercapnia can be reversed by the administration of supplemental oxygen or by normalizing the patient’s Paco2 by external stimulation of the patient to wakefulness.

17. PULMONARY EDEMA Post obstructive Pulmonary edema is a transudative edema produced by the exaggerated negative intra-thoracic pressure generated by an inspiratory effort against closed glottis. Treatment includes supportive and includes supplemental oxygen, diuresis and in severe cases post-pressure ventilation of the patient’s lungs.

18. Transfusion –related lung injury. It typically occurs within 1-2 hours after the transfusion of plasma-containing blood products including packed red blood cell , whole blood ,fresh frozen plasma or platelets. Treatment for this is supportive care , supplemental oxygen and drug induced diuresis.

19. POST OPERATIVE NAUSEA AND VOMITING A study conducted by Grief and colleagues randomized 231 patients undergoing elective colon resection to receive 30%or 80% oxygen. In the study , administration of 80% supplemental intraoperatively and postoperatively reduced the incidence of post operative nausea to two fold. Kober and colleagues found that hyperoxia reduced the incidence of nausea and vomiting fourfold compared with patients breathing air. Aprepitant (EMEND) , a substance P antagonist blocks the neurokinin 1 (nk1 receptor) is found to be effective in high- risk patients and refractory cases of POST-operative Nausea and vomiting.

20. Wound infections – Supplemental oxygen appears to reduce the incidence of surgical wound infections in patients undergoing colorectal surgery. Recently a randomized controlled study of 300 patients in 14 Hospitals found that patients who received supplemental oxygen had 30% reduction in surgical site infection. Patients who are stable after head and neck surgery may not be candidates for face mask oxygen because of the risk of pressure necrosis on incision sites and microvascular muscle flaps.

21. Hemodynamic instability SYSTEMIC HYPERTENSION- patients with a history of essential hypertension are at a greater risk for significant systemic hypertension in the PACU Surgical procedures most commonly associated with postoperative hypertension are carotid endarterectomy and intracranial procedures. Factors leading to postoperative hypertension are Preoperative hypertension , arterial hypoxemia , hypervolemia , emergence excitement, shivering , Drug rebound , increased intracranial pressure.

22. HYPOVOLEMIA Systemic hypotension in the Post anaesthesia care unit is often due to decreased intravascular fluid volume and preload. Common causes of decreased intravascular fluid volume in the immediate postoperative period include ongoing third space loss of fluid. Inadequate intra-operative fluid replacement especially in patients who undergo major intra-abdominal surgeries. Loss of sympathetic nervous system as a result of neuraxial blockade. Ongoing bleeding should be ruled out in patients with hypotension who have undergone surgical procedure in which significant blood loss is possible.

23. DISTRIBUTIVE ( DECREASED AFTERLOAD) Reasons for distributive shock in post-operative room are Iatrogenic sympathectomy secondary to regional anaesthetic techniques. Critical illness and sepsis. A high sympathetic block to T4 decreases vascular tone and block the cardioaccelerator fibres, if not treated promptly , then the resulting bradycardia with hypotension leads to cardiac arrest. Vasopressors – phenylephrine and ephedrine are used in hypotension caused by residual sympathetic block. Ephedrine 5-10mg i.v

24. Allergic anaphylactic reaction may be the cause of hypotension secondary to allergic reaction. Epinephrine is the drug of choice to treat hypotension secondary to allergic reaction. If sepsis is the cause of hypotension in the PACU, then blood should be collected for culture and empirical antibiotic therapy should be initiated before shifting the patient. Vasopressin ( 0.01 – 0.05unit/min) improves mean arterial blood pressure.

25. CARDIOGENIC MYOCARDIAL ISCHEMIA- interpretation of changes in the ECG in the PACU is influenced by patient’s cardiac history and risk index. In patients at low risk younger than 45 years of age with no cardiac history and the only risk factor ie Post-operative ST segment changes on the ECG , do not usually indicate myocardial infarction. Causes of ST changes in patients at low risk include anxiety , esophageal reflux , hyperventilation and hypokalemia. Whereas in high risk patients with known cardiac disease any ST or T wave changes , Serum troponin levels be checked and further managed.

26. CARDIAC DYSRHYTMIAS. TACHYCARDIA- causes of perioperative sinus tachycardia are :- Pain. Agitation ,hypoventilation with associated hypercapnia, hypotension , hypoglycemia fever or infection ,hypovolemia and shivering. Hyperthyroidism , pericarditis , pericardial tamponade , malignant hyperthermia. Treatment includes -correction of underlying cause and treatment with i.v beta blockers.

27. RENAL DYSFUNCTION OLIGURIA Intravascular volume depletion – the most common cause of oliguria in the immediate post-operative period is the depletion of intravascular fluid volume, in this regard, a fluid challenge (500 to 1000ml) of crystalloid is usually effective. volume resuscitation to maximise renal perfusion is particularly important to prevent on going ischemic injury and development of acute tubular necrosis.

28. Post operative oliguria PRE-renal causes Hypovolemia can happen when there is bleeding,sepsis , third space loss , inadequate volume resuscitation Hepatorenal syndrome Low cardiac output Renal vascular obstruction Intraabdominal hypertension. RENAL Ischemia ( acute tubular necrosis) Radiographic test dyes Rhabdomylosis Tumor lysis Hemolysis post- renal causes are – surgical injury to the ureters Obstruction of the urters with clots or stones. Urinary catheter obstruction

29. Post operative urinary retention Post operative urinary retention can cause bladder overdistension and permanent detrusor damage. USG can measure bladder volume and identify urinary retention in the PACU Urinary retention is defined as bladder volume greater than 600 ml in conjunction with an inability to void within 30 minutes.

30. Alkalization of the urine with sodium bicarbonate has shown to provide additional protection. 154 meq /l should be infused at a rate of 3ml/kg/ hr for 1hr before injection of contrast agent followed by 1ml/kg/ hr for 6hrs. INTRAABDOMINAL HYPERTENSION Elevated intrabdominal hypertension can impede renal perfusion and leadto renal ischemia and post-operative renal dysfunction Abdominal compartment syndrome is defined as IAP greater than 20 mmhg with / without abdominal perfusion pressure less than 50 mmhg

31. BODY TEMPERATURE AND SHIVERING Brain and spinal cord do not recover simultaneously from general anaesthesia . The more rapid recovery of spinal cord function is thought to result in uninhibited spinal reflexes exhibited as clonic activity. Ondansetron and clonidine have shown to be effective in abolishing shivering. Meperdine 0.35 to 0.4 mg/kg is most commonly used.

32. DELIRIUM Approximately 10% patients older than 50 yrs of age who undergo elective surgery will expreince some degree of post operative delirium within the first 5 postoperative days. The incidence is significantly higher in hip fracture, bilateral knee replacement The American psychiatric association defines delirium as acute change in cognition or disturbance of consciousness that cannot be attributed to a pre-existing medical condition , substance intoxication or medication.

33. Persistent postop delirium is generally seen in older adult patients more than 70 yrs Other risk factors are alcohol abuse , history of delirium Management – Patients who are severely agitated may require restraints to control their behaviour and to avoid self inflicted injuries. Sedatives are used.

34. Delayed awakening Residual sedation from drugs used during anaesthesia is the most important frequent cause of delayed awakening in the PACU Naloxone 20-40 microgram Is used to antagonize the opiod induced analgesia Physiostigmine is used to reverse the central nervous system sedative effects of anticholinergic drugs especially scopolamine. Flumazenil 0.2mg is a specific antagonist for the residual depressant effects of benzodiazepines.

35. DISCHARGE CRITERIA In 1970 Aldrete and kroulik developed post anaesthetic scoring system to monitor recovery A score 9 out of 10 is considered adequate for discharge from the PACU

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