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Perianesthetic Pharmacology Drug Apps 2 Epocrates http://www.epocrates.com Medscape http://www.medscape.com/public/mobileapp Drugs.com http://www.drugs.com/mobile.html Anesthetic Agents 3 Inhalation agents (IAs) CNS is the target system. Depresses the reticular activating system, which causes unconsciousness. Alters neuronal excitability throughout the CNS. General Effects of IAs 4 CNS Cause unconsciousness through depression of excitable tissue at all levels. Decrease ICP through vasodilatation. Hyperventilation counteracts this by causing hypocarbia and vasoconstriction. General Effects of IAs 5 Cardiovascular Depressant effect on the myocardium and vasculature. cardiac output, PVR, and SVR. Variable effect on the heart rate. General Effects of IAs 6 Respiratory Bronchodilatation. Affects the ventilatory control. Dulls the response to a rising CO2. This effects continues into the postop period. General Effects of IAs 7 GI – decreased motility. Mild to moderate relaxation of skeletal muscle. Temperature regulation Hypothalamic regulation is diminished. Body’s effector mechanisms (shivering, vascular control, behavior choices) are inactivated. Fluothane – halothane 8 Introduced in 1956. Sweet, non-irritating odor. Rapid onset. Slow arousal. High incidence of postop shivering. Sensitizes the myocardium to adrenergic agents ventricular ectopy, VT and V fib. Fluothane – halothane 9 60-80% excreted unchanged by the lungs. Rest is metabolized by hepatic microsomal enzymes. Halothane hepatitis – caused by a metabolite that attaches to the liver and causes the body to not recognize the liver as “self”. Is a trigger for malignant hyperthermia. Forane - isoflurane 10 Has a pungent odor. Not used for induction, but for maintenance of anesthesia after induction with IV agents. Excellent skeletal muscle relaxation. Eliminated almost exclusively by the lungs. Higher incidence of PONV. Postop shivering may be increased due to intraop vasodilation. Suprane - desflurane 11 Newest inhalation anesthetic. Used for maintenance of anesthesia. Rapid onset and offset. Rapid offset leaves no lingering analgesia; must be supplemented. Is an airway irritant. High incidence of breath-holding, apnea, coughing, and increase in oral secretions. Not used in children, as it has a high incidence of laryngospasm. Ultane - sevoflurane 12 Is non-irritating to the respiratory tract, and has a pleasant smell. Can be used for induction and maintenance of anesthesia. Fast onset and offset, but not as fast as desflurane. Rapid offset leaves no lingering analgesia; must be supplemented. Does not sensitize the myocardium to adrenergic agents. Fluoride metabolites – use with caution in renal dysfunction. 13 SevoFlo 14 Unlike many other inhalation anesthetics, which have a pungent or irritating odor, SevoFlo smells sweet, similar to fruit-flavored chewing gum. Your pet . . . will fall asleep quickly and with minimal stress. When the medical procedure is complete, your pet will usually begin waking up within a few minutes. 15 Waste Anesthetic Gases in PACU Most inhalation agents and nitrous oxide are excreted unchanged by the lungs. Prolonged exposure reproductive and neurologic problems, liver and kidney disease. Diprivan - propofol 16 Is a sedative-hypnotic in a class by itself. Is a milky emulsion composed of eggs and soy. Effects: Rapid induction with frequent apnea. No analgesia. Rapid offset, with minimal PONV. Not a triggering agent for MH. Diprivan - propofol 17 Less hangover Pts are responsive earlier Less PONV Pts more alert and can eat and drink earlier Less psychomotor impairment – earlier ambulation Ketamine - Ketalar 18 Produces dissociative anesthesia. Feeling of dissociation from environment. Used for induction and maintenance of anesthesia. Intense analgesic properties. Almost half of pts over 30 yo exhibit delirium or excitement on emergence. Can induce hallucinations. Stages of Anesthesia 19 Stage IV: Medullary depression Overdose of anesthetic. Stage III: Surgical anesthesia Cessation of spontaneous respirations No reflexes. Stages of Anesthesia 20 Classic reference points. Stage II: Stage of delirium Hallmark is involuntary activity. High risk of aspiration, laryngospasm, bronchospasm. Dysphoria, restlessness, muscle rigidity, urinary and fecal incontinence, BP and HR. Stage I: Stage of analgesia Can follow simple commands. Protective reflexes are intact. Reflexes as a guide to depth of anesthesia 21 Reflexes come back in this order: lid or corneal reflex swallow cough pupillary Neuromuscular Junction 22 Neuromuscular Junction 23 Nerve impulse causes release of acetylcholine (ACh) into the synaptic cleft. ACh diffuses across the synaptic cleft, and binds on the post-synaptic fibers of a muscle fiber. Results in a membrane depolarization, and a muscle contraction. Neuromuscular Junction 24 ACh is rapidly broken down by acetylcholinesterase (AChE), which is stored on the muscle fiber. In addition, ACh is no longer released. The muscle contraction is terminated. Depolarizing Muscle Relaxant 25 succinylcholine – Anectine – Quelicin - Sucostrin Is the only DMR in use in the US. Works in 1-1.5 min., and wears off in 4-8 min. A molecule of sux is 2 linked molecules of ACh. Works as an agonist; occupies the receptor and stimulates it is exhausted. Succinylcholine 26 Effects: Paralysis and apnea. No effect on CNS. No analgesia. Fasiculations. Myalgias. Succinylcholine 27 Effects: Hyperkalemia in susceptible pts. Can cause cardiac standstill due to hyperkalemia. Is a triggering agent for MH. Avoid in children for this reason. Succinylcholine 28 Is broken down by pseudocholinesterase, also called plasma cholinesterase (PC). This enzyme can be under produced or absent; this deficit is genetic, and runs in families. PC and serum albumin tend to be directly related. Sux in the absence of PC will result in paralysis that lasts for several hrs to a day. Non-Depolarizing Muscle Relaxants 29 NDMR occupy the cholinergic receptor on the muscle fiber, resulting in paralysis. ACh is still released, and competes for the binding site. Non-Depolarizing Muscle Relaxants 30 Paralysis occurs from fine to gross movement. As the pt recovers from the paralysis, it progresses from gross to fine movement. Sequence of return: Diaphragm intercostal muscles limbs & neck hands jaw eyes Non-Depolarizing Muscle Relaxants 31 Effects of NDMR Paralysis with apnea. No effect on CNS. None of the effects seen with sux, i.e., fasciculations, myalgia, hyperkalemia. No analgesia. Onset is variable, but averages several minutes. Offset depends on the agent; can be 20-30 minutes to 4-5 hours. Curare 32 Comes from an arrow poison used in the Amazon. First discovered by the Europeans in the 16th century. First used in the US in the 1940s. Causes histamine release. Is cumulative, and can cause reparalysis, or recurarization. Not commonly used. NonDepolarizing Muscle Relaxants 33 Tracrium – atracurium Intermediate acting Hoffman degradation Nimbex – cisatracurium Intermediate acting 80% by Hoffman degradation Pavulon – pancuronium Long acting Histamine release NonDepolarizing Muscle Relaxants 34 Zemuron – rocuronium Short acting Onset 1 min; offset 15-20 min No histamine release Norcuron – vecuronium Intermediate acting No histamine release No CV effects – useful in cardiac surgery Awareness During Anesthesia 35 Incidence of 0.1-0.2%. Very frightening experience. One-half are reported in PACU. 70% experience post traumatic stress syndrome: sleep disturbances, nightmares, panic attacks, flashbacks, avoidance of medical care. Awareness During Anesthesia 36 Higher incidence during C-sections, cardiac surgery and trauma. Lighter anesthesia is used due to limited cardiac reserve, hypovolemia, hypotension, or fear of decreasing the uterine tone and increasing blood loss. Higher incidence with total IV anesthesia. Lower incidence with inhalation anesthetics. BIS Monitor 37 Bispectral Index Monitor. Is an EEG-based monitor of anesthetic effect. Is used as an indicator of the level of sedation. Can greatly eliminate intra-operative recall. Used as an indicator to the depth of anesthesia. Items for Further Review 38 Specific muscle relaxants How they are metabolized How long they last Specific uses Neuromuscular Junction 39 NDMR Reversal Agents 40 Are anticholinesterase agents. Block the enzyme AChE, resulting in more Ach in the neuromuscular junction. Results in reversal of the paralysis, and normal muscle contraction. NDMR Reversal Agents 41 Also cause: Bradycardia, CO. Bronchoconstriction. GI peristalsis: urination, defecation. To counteract these effects, must co-administer an antimuscarinic agent. Atropine Robinul - glycopyrrolate Effects of Antimuscarinics 42 HR. Inhibit peristalsis and micturation. Cause mydriasis. Atropine crosses the blood brain barrier, and can cause a central anticholinergic syndrome. Robinul does not cross the BBB. Anticholinergics 43 Neostigmine - prostigmine Enlon - edrophonium Enlon Plus – edrophonium and atropine Regonol - pyridostigmine To reverse a block, must have some recovery of muscle function. Inadequate Muscle Strength 44 Pt can be brought to PACU not fully reversed. Pt can be WNL on admission to PACU, and reparalyze. It is rare, but could happen in OPS. Ask the pt to hold head up x 5 sec. Very frightening experience. Malignant Hyperthermia 45 Rare, potentially fatal disorder of skeletal muscle triggered by certain anesthetic agents. Before 1970, mortality was 70%. Dantrolene was introduced in 1979; now the mortality is 6-7%. Malignant Hyperthermia 46 MH is an autosomal dominant genetic trait, and runs in families. Ask this question in anesthesia questionnaires. Incidence is 1:20000 to 1:50,000 in adults, and 1:15,000 in children. Many cases undetected Never anesthetized Short anesthetic period Triggering Agents 47 All inhalational anesthetics halothane isoflurane desflurane sevoflurane Succinylcholine NOT triggering agents: All muscle relaxants EXCEPT sux Propofol Nitrous oxide Diagnosis 48 No lab test for MH. Must obtain a thumb-sized skeletal muscle biopsy from the thigh that can only be done at 4 hospitals in the US, and 1 in Canada. Cost is $6000 to $10,000. Muscle contracture testing. Genetic testing can be done at 2 hospitals in US. Clinical Presentation 49 Triggering agent release of abnormal amounts of calcium from skeletal muscle. Results in sustained skeletal muscle contraction. Subsequently causes hypermetabolism, muscle injury and muscle rigidity. Increased O2 consumption and CO2 production precede hyperthermia. Initial Signs and Symptoms 50 Increasing ETCO2 Tachypnea and tachycardia Hypoxemia Muscle rigidity Trismus – masseter muscle rigidity Later Signs and Symptoms 51 Acidosis Oliguria Myoglobinuria; cola-colored urine Caused by rhabdomyolysis Ventricular irritability – V tach Hyperthermia Hypertension followed by hypotension Flushing, mottling of skin Lab Values 52 CK Severe respiratory and metabolic acidosis. Altered coagulation indices. magnesium, calcium, potassium. Prognosis 53 The combination of high temperature, acidosis, hypoxemia and rhabdomyolysis can result in death. Recrudescence (reoccurrence) can occur in 25% of cases. Treatment 54 Follow the instructions on the MHAUS poster. www.mhaus.org. 1.800.MH.HYPER. Dantrolene is the drug of choice. It is a muscle relaxant that decreases the calcium release from the skeletal muscle. All facilities that use IAs should have 36 vials of dantrolene. Dantrolene 55 Initial dose is 2.5 mg/kg. More than 10 mg/kg can be needed for treatment. Should be fully effective in 5-10 min. after administration. Is not very soluble in water. Mix with sterile water without bacteriostatic agents. Revonto 56 Is a new preparation of Dantrolene. Enhanced reconstitution time of 20 seconds or until the solution is clear. Use sterile water without a bacteriostatic agent. Other Treatments 57 Hyperventilation with 100% O2 Treat acidosis with bicarb. Avoid LR, as it can worsen the acidosis. Treat hyperkalemia with insulin and glucose. Use lidocaine to treat ventricular ectopy. Other Treatments 58 Do not use calcium channel blockers. Can cause severe hyperkalemia and myocardial depression. Active cooling of core, using several modalities. Elective surgery for MH-susceptible pts 59 Avoid triggering agents. Can give propofol, opioids, NDMRs, local anesthetics. Will use TIVA. Do not need to be pretreated with oral dantrolene; can worsen pre-existing muscle disease. MH Pts in an OPS 60 May be done in an out-patient setting. A minimum of 1 hr in PACU and 1.5 hrs in Phase II are recommended. Discharge after MH Symptoms 61 Masseter spasm Severe spasm requires overnight observation. Milder spasm requires 12 hrs observation; any additional symptoms will require admission. Symptoms include: cola-colored urine, temp, pulse, abnormal acid-base Moderate Sedation 62 Midazolam approved in 1986. From 1986-88, there were over 80 midazolam- related deaths. In 1991, a position statement on The Role of the RN in the Management of Patients Receiving Conscious Sedation was published. Continuum of Sedation 63 Minimal sedation (anxiolysis): pt responds appropriately to verbal commands. Moderate sedation Depressed LOC. Pt responds to verbal commands; may be accompanied with light tactile stimuli. Can maintain own airway. Protective reflexes are intact. Continuum of Sedation 64 Deep sedation Pt may need assistance maintaining the airway. Spontaneous ventilation may be inadequate. Cannot easily be aroused. Respond purposefully after repeated or painful stimuli. Anesthesia Criteria 65 Pre-sedation evaluation. Medications must be ordered by a qualified physician who is credentialed to perform conscious sedation at your facility. A qualified RN must administer the meds and monitor the pt. Must have no other duties that would leave the pt unattended, or compromise the continuous monitoring of the pt. Criteria 66 Need emergency equipment available. Need protocols for potential complications. Monitoring must include: BP, HR, ECG, SpO2, resp. rate, and level of sedation. Vital signs must be taken every 5 minutes. Pt is discharged according to specific criteria. Benzodiazepines 67 Bind to specific receptor sites in the CNS, and inhibit excitatory impulses. Effects: Anxiolysis Sedation Hypnosis Anticonvulsant properties Skeletal muscle relaxation Valium - diazepam 68 Introduced in 1961. Is the ‘gold standard’ against which all other benzos are compared. Duration is 3-4 hrs; active metabolite has a duration of action of 21-37 hrs. Has a high incidence of venous irritation. Diazemuls. Versed - midazolam 69 Is 3-4 times stronger than Valium. Duration of action is 60-90 minutes; has no active metabolites. Does not burn on injection. Causes antegrade amnesia, but not retrograde amnesia. Dose is 0.5 – 2.5 mg to 5 mg. Titrate to effect: somnolence, slurring of speech, nystagmus. Romazicon - flumaxenil 70 Is a competitive benzodiazepine antagonist. Rapidly and effectively antagonizes the sedation. Is partially effective in reversing the respiratory depression. Side effects: tachydysrhythmias, hypertension, convulsions. Romazicon - flumaxenil 71 Dose: 0.2 mg IV over 15 sec. May repeat in 1 minute intervals up to a maximum of 1.0 mg. Onset: 1-2 minutes. Duration: 45-90 minutes. Monitor the pt for resedation. Diprivan 72 Is used in many settings, such as endoscopy or cardiac cath labs. Routinely causes deep sedation. In Oklahoma, RNs may not administer anesthetic agents. Diprivan is an anesthetic agent. Analgesia 73 Pain is what the pt says it is. Need to use an objective pain tool or tools. Anticipate pain in almost all postsurgical pts. Chronic Pain Pts 74 May be on many kinds of meds. Opioids. Tri-cyclic antidepressants are used for neuropathic pain in the absence of depression. Anticonvulsants, such as Neurontin, Dilantin, Tegretol, Depakote or Klonopin, are used to treat peripheral nerve syndromes such as posttraumatic neuralgia. Tolerance vs. Addiction 75 Tolerance Larger dose of opioid is needed to maintain the original effect. Physical dependence develops. Addiction Pattern of compulsive drug use. Continuing craving for an opioid. For effects other than pain relief. Abstinence Syndrome 76 Anxiety, irritability. Chills alternating with hot flashes. Salivation, lacrimation, rhinorrhea. Diaphoresis, piloerection. Nausea/vomiting, abdominal cramps. Insomnia. Morphine 77 Is the ‘gold standard’ against which all other opioids are measured. Made from opium or poppy straw. Affects the (mu) receptors. Expected effects are analgesia and constipation. Onset: 1-5 minutes. Peak: 20 minutes. Duration: 4 hrs. Morphine 78 Other effects: Drowsiness Mental clouding Respiratory depression which is enhanced by general anesthetics, sedatives GI motility and nausea/vomiting Urinary retention Miosis Histamine release that causes hypotension. Altered thermoregulation slightly lower body temperature Sublimaze - fentanyl 79 Is 80-100 times stronger than morphine. Is a synthetic meperidine derivative. Most commonly abused drug in the perioperative arena. Onset is 30-60 seconds; duration of action is 3060 minutes. Respiratory depression can outlast analgesia. Can cause muscle rigidity with high doses. No histamine release. Demerol - meperidine 80 Produces a metabolite called normeperidine. Is a CNS excitotoxin that causes anxiety, tremors, muscle twitches, and seizures. These effects are not seen for 2-3 days; will not occur immediately after surgery. Should not be used for more than 48 hrs for acute pain, and should not be used for chronic pain. Demerol - meperidine 81 Is metabolized in the liver. In pts with cirrhosis, the half-lives of both meperidine and normeperidine are prolonged by up to 80%. Demerol 75-100 mg is equivalent to MS 10 mg. Usual dose of Demerol is 50 mg. Demerol is frequently under dosed. Demerol 82 Is useful for postoperative shivering, esp. in the absence of hypothermia. Dose is 12.5-25 mg. Is thought to act through a K receptor mechanism. Dilaudid - hydromorphone 83 5-10 times more potent than morphine. Less sedating than morphine. No histamine release. Less nausea and vomiting. More potent analgesia. Dilaudid - hydromorphone 84 Dose is 0.2mg (equianalgesic to 1 mg of morphine). Onset 1 min. Peak 5-20 minutes. Duration of action 2-4 hrs. Intramuscular Injections 85 Not recommended. Pain from injection itself. Erratic analgesia due to varied absorption. Useful occasionally in outpatient settings. Narcan - naloxone 86 Is an opioid antagonist that works at the mu receptor. Reversal of respiratory depression is seen in 1-2 minutes, and lasts for 60 minutes. Dose: mix 0.4 mg of Narcan in 9 ml NSS. Results in a concentration of 0.04 mg/ml. Give 1 ml or 0.04mg at a time until desired results are achieved. Negative Pressure Pulmonary Edema 87 Is caused by generating negative intrapleural pressures against an obstructed airway. Creates an elevated hydrostatic pressure that forces fluid out of the vasculature and into the lungs. Accompanying hypoxia causes vasoconstriction and an increased venous return. Negative intrathoracic pressures decrease the ejection fraction of the heart. All result in pulmonary edema. Negative Pressure Pulmonary Edema 88 Also seen after laryngospasm or croup. There is no intrinsic defect in the myocardium. Signs and symptoms: Frothy sputum Hypoxemia Tachypnea SOB Rales CXR that shows diffuse infiltrates. Negative Pressure Pulmonary Edema 89 Treat with: Diuretics. Supplemental oxygen. Intubation and PEEP if necessary. Morphine, Versed. Usually resolves quickly – within 24 hours. Oral Analgesics 90 Mainstay of outpatient pain management. Useful for longer pain control. Oral Analgesics 91 Hydrocodone Mod. to severe pain 1-2 tabs q4-6 hrs Max 8 tabs/day Oxycodone Mod. to severe pain 1-2 tabs q4-6 hrs Max 8 tabs/day Better analgesia than hydrocodone Hydrocodone 92 Lortab –500 mg acetaminophen. Lorcet 10/650 – 10 mg hydrocodone and 650 mg acetaminophen. Vicodin – 5 mg hydrocodone and 500 mg acetaminophen. Vicodin ES – 7.5 mg hydrocodone and 750 mg acetaminophen. Oxycodone 93 Percocet 5/325 - 5 mg oxyocodone and 325 mg acetaminophen. Percocet 7.5/500 – 7.5 mg oxyocodone and 500 mg acetaminophen. Percocet 10/650 - 10 mg oxyocodone and 650 mg acetaminophen. Percodan – 5 mg oxyocodone and 325 mg aspirin. Acetaminophen 94 3 gms a day is max dose. This maximum is new as of July 2011. Can cause liver damage, especially with impaired liver function. Is the leading cause of liver failure. 8 Lortabs a day are max. Percocet 10/650 – 6 pills a day are max. Analgesia Prior to Discharge 95 Give pt oral analgesic. IV meds will wear off before the pt gets the prescription filled. Pt will frequently be unable to get pain under control without this sequence. Chronic Pain Control 96 Meds don’t contain acetaminophen due to potential for liver toxicity. Have an immediate release med and a time-release med, i.e. OxyIR and Oxycontin, MSIR and MsContin. Have pt take their time-release med the morning of surgery. Items for Further Review 97 Theories of pain – transmission, receptors, modalities of pain control. Onset, duration of action, and specific side effects of analgesics. NSAIDs 98 Can be given preoperatively as well as postoperatively. Their anti-inflammatory effects are a logical choice for the inflammation that accompanies surgery. Diminish or prevent central as well as peripheral sensitization. No sedation; no impairment of GI motility. Toradol - ketorolac 99 Can be given parenterally. Effective in relieving moderately severe pain, esp. when given in conjunction with opioids. Can only be given for 5 days, due to increased risk of GI bleeding. Lower dose with renal impairment. Contraindicated in pts with prior hx of allergic reactions to ASA or other NSAIDS, GI bleeding or peptic ulcer disease. Ofirmev - acetaminophen 100 Can be given IV Approved in pts 2 y/o and older Indicated for: Mild to moderate pain. Moderate to severe pain in conjunction with opioids Reduction of fever Do not exceed maximum recommended daily dose of acetaminophen. Cost: $10.75/vial. Lidocaine 101 Medium-acting, quick, potent. High incidence of sleepiness and dizziness. Duration 30-120 minutes. Depresses laryngeal and tracheal reflexes. Also available in Lidoderm patches. Bupivicaine 102 Trade names: Marcaine, Sensorcaine. High potency, long duration of action of 3-10 hrs. Prolonged anesthetic and analgesic action. Ropivicaine 103 Trade name: Naropin. High potency, similar to bupivicaine. Produces less motor blockade than bupivicaine. Local Anesthetics 104 Does help with postop pain. Can result in systemic absorption. Infusion pumps of local anesthetic into incision. Systemic Absorption of Local Anesthetics 105 CS stimulation followed by CNS depression. Restlessness, muscle twitching, tremor, lightheadedness, tinnitus, circumoral tingling progressing to seizures. CNS stimulation phase may be skipped entirely and progress straight to CNS depression. Lethargy may be the only symptom. CV: Decreased myocardial electrical activity, conductivity, and force of conduction. Treatment of Systemic Absorption 106 Administer oxygen. Be prepared to administer a benzodiazepine for seizure activity. Monitor HR and ECG carefully. Scalene Block 107 Infiltration of a local anesthetic into the brachial plexus using a nerve stimulator to ascertain correct placement. Provides analgesia after shoulder surgery for 12-36 hours. Should be done preop not postop. Scalene Block 108 Side effects: Droopy or reddened eye or eyelid. Dysphagia. Raspy cough. Hoarse voice. Diaphragmatic hemi paralysis resulting in hypoventilation, hypoxia, and dyspnea. Contraindicated in pts with impaired pulmonary status. Scalene Block 109 Adverse effects: Pneumothorax. Permanent nerve injury. Paresthesia lasting more than 1 week. Systemic toxic reactions to the local anesthetic. Femoral Block 110 Infiltration of a local anesthetic into the sciatic and femoral nerve plexus using a nerve stimulator to correctly place the needle. Provides analgesia for 12-36 hours after knee surgery – ACLs, lateral release. Side effects: Inability bear weight on affected leg. Urinary retention. Delayed diagnosis of compartment syndrome. Bier Block 111 Exsanguination of the surgical arm with an Esmarch bandage. Application of a tourniquet, then infusion of a local anesthetic through a previously placed saline lock. Provides regional anesthesia during the surgery. Pt will require additional analgesia postoperatively. Monitor for systemic effects of the local anesthetic. Epidural and Intrathecal Analgesia 112 Epidural: drug in injected outside the dura mater, and must cross the blood brain barrier. Intrathecal: drug is injected through the dura mater into the CNS. Smaller doses of drugs are used. Provides potent analgesia without the systemic side effects of parenteral opioids. Must use preservative-free meds. Epidural and Intrathecal Analgesia 113 Intrathecal: dose is 0.2 – 1.0 mg MS. Duration of analgesia is 8-16 hrs. Epidural: Morphine – onset of action is 45-60 minutes. Duration of action is 12-24 hrs. Rostral spread of morphine can be a problem. Fentanyl – onset of action is 5-10 minutes. Duration of action is 5-6 hrs. Less chance of rostral spread due to chemical structure o the drug. Pain Control 114 Be cautious with parenteral opioids. In PACU, will probably need to give opioids until epidural begins working. Parenteral opioids will augment the potential for respiratory depression caused by epidural. Side Effects 115 Delayed respiratory depression – due to rostral spread of morphine; not really a factor with fentanyl. Pruritis - treat with antihistamines, low-dose Narcan. Nausea/vomiting – treat with anti-emetics. Side Effects 116 Urinary retention – assess frequently for bladder distention. May require a catheter. Hypotension – due to sympathetic blockade. Treat with fluids. Systemic local anesthetic toxicity (if local anesthetic is used). Epidural hematoma. Spinal Anesthesia 117 Injection of local anesthetic through the dura mater, into the CNS. Provides anesthesia to the lower half of the body. Local anesthetic can spread upward from the injection site; is controlled by pt position and addition of dextrose. Spinal Anesthesia 118 Spinal Anesthesia 119 Ventilatory inadequacy: Pt may feel dyspneic due to inability to feel intercostals. Numbness of hands. Hypotension. Apnea. Sympathetic blockade is 3-6 dermatomes higher than the sensory block. Spinal Anesthesia 120 Sympathetic blockade results in hypotension due to vasodilatation. Treat with: Hydration. Put the foot of the bed up to increase venous return. Ephedrine 5-10 mg IV. Side Effects 121 Bradycardia progressing to asystole. Urinary retention. Loss of temperature regulation below level of spinal. Postdural headache. Spinal Anesthesia 122 Reappearance of neurologic functions: Deep pressure motor function proprioception cold and warmth pain autonomic functions. Autonomic functions include: Vasomotor. Bladder control. Discharge Criteria after Spinal Anesthesia 123 Normal perianal pinprick sensation. Plantar flexion of the foot; normal proprioception of the big toe. No residual motor block. Absence of orthostatic hypotension. BP in sitting and supine positions. Less than 10% drop between BPs. PCA Pumps 124 Need a basal infusion as well as the intermittent infusion. Initiate prior to leaving PACU. Need additional analgesia to obtain adequate pain control in PACU. Postoperative Nausea and Vomiting 125 Implications of PONV: Is often feared by pts more than surgical pain. Incidence of the literature ranges from 20-30%. The incidence among high risk pts can be as high as 70-80%. Raises institutional costs due to the cost of the antiemetics and increased nursing time. Each incidence of vomiting delays discharge from PACU by an average of 20 minutes. Can lead to an increased LOS. Factors That Increase the Risk of PONV 126 Age. Children Decreases after 70 y/o. Female gender. History of previous PONV. History of motion sickness. Delayed gastric emptying. Pregnancy Obesity Diabetes Factors That Increase the Risk of PONV 127 Type of surgery: ENT ophthalmic Plastic and reconstructive Gynecologic and breast Laparoscopy and abdominal Increasing duration of surgery increases the risk of PONV. Use of opioids, nitrous oxide, reversal agents. Factors That Decrease the Risk of PONV 128 Smokers have a lower incidence of PONV. Propofol, TIVA. Regional anesthesia. Physiology of PONV 129 NV is a complex process regulated by the emetic center in the medulla. This center receives input from: Chemoreceptor trigger zone. From the brainstem, cortex, and certain organs, such as the heart, testes, gastrointestinal tract. Chemoreceptor Trigger Zone 130 Serotonin; sometimes called 5-HT3 receptors. Dopamine. Histamine. Cholinergic. Antiemetic Drugs 131 Serotonin antagonists – appear to be the most efficacious of the antiemetics. Zofran – ondansetron Kytril - granisetron Anzemet – dolasetron Zofran Appears to have better antivomiting effect than antinausea effect. No value of additional dose if maximum dose of 4 mg has been given within 24 hours. Dopamine Blockers 132 Reglan – metaclopramide. Enhance gastric emptying. Most common dose of 10 mg IV not effective for prophylaxis. Can cause extrapyramidal reactions. Phenothiazines: Compazine – chlorpromazine. Phenergan – promethazine. Extravasation risk. Can cause extrapyramidal reactions. Dopamine Blockers 133 Inapsine – droperidol. FDA black box warning in 2001. ECG monitoring for 2-3 hrs after dose. Can cause extrapyramidal reactions. Scopolamine Transdermal patch should be applied 4 hrs before the end of surgery, of preop for short surgeries. Dose is delivered for 3 days if left on. Side effects: dry mouth, dizziness, dilated pupils, urinary retention, drowsiness. Prophylaxis of Pts at High Risk for PONV 134 Several kinds of antiemetics are given. Dexamethasone 4-8 mg; give at least 2 hours before the end of surgery. Serotonin antagonist – Zofran, Anzemet. An phenothiazine – Phenergan. An anticholinergic – Scop patch. Hydrate the pt. Prophylaxis of Pts at High Risk for PONV 135 Use propofol; avoid nitrous oxide and IAs. Minimize use of postop opioids by using regional anesthesia. Relief Band – provides acustimulation. Treatment of PONV 136 Give a 5HT3 blocker if not already given. Don’t give if one was already given. Treat with a drug from a different class. Hydrate. Propofol 20 mg – sub hypnotic dose. Ginger ale. Items for Further Review 137 Nitrous oxide. Acid-base and interpretation of ABGs. Induction agents.