Exam 2 RX- Pre, Intra, and Postoperative Medication Management

In cases in which prophylaxis is warranted (Abdominal surgery, orthopedic surgery, urologic, gynecologic, rectal surgery, and surgery for malignancy), the following drug is best to prevent DVT?

*Enoxaparin (Lovenox) is administered at 20 mg subcutaneously 1-2 hours before surgery and once daily postoperatively for moderate-risk patients. A dose of 40 mg with the same schedule is administered to high-risk patients.*

Deep Vein Thrombosis Prophylaxis and Treatment

*Enoxaparin sodium (Lovenox) is administered at 1 mg/kg q12h subcutaneously or at 1.5 mg/kg/d subcutaneously. The single daily dose should not exceed 150 mg. ● Tinzaparin sodium is administered at 175 anti-Xa IU/kg/d subcutaneously daily.*

● Hold aspirin and platelet active-nonaspirin NSAIDs before surgery why?

Because the inhibitory effect of aspirin on platelet aggregation may persist for 7-10 days, discontinuing aspirin at least 1 week before surgery is prudent. ● Their effect on mucosal wound healing has not been studied in humans. ● In those patients with inflammatory arthritis who are dependent on their NSAID therapy for control of their symptoms, withholding therapy in the perioperative period may result in increased pain and stiffness. This effect should be anticipated, and alternative therapy, such as analgesics or low-dose corticosteroids, should be considered to prevent pain, which may result in delayed postoperative rehabilitation.

Pt's with CAD undergoing surgery should be monitored with an EKG for evidence of MI and provided therapy to prevent and treat ischemia perioperatively. What medication is routinely given?

Beta blockers (Atenolol) provide the best prevention of ischemia

What is done for control of a-fib and SVT prior to surgery?

Continue digoxin

IV lidocaine and beta blockers can be used intraoperatively as needed. However what is done for amiodarone?

D/C amiodarone day before surgery and restart after pt begins eating again (has long ½ life 30-60 days)

Why is the limit on liquids being given to a patient given a time limit?

Liquids are cleared from the stomach within 2 hours of ingestion. Therefore patient can be given their routine medications with sips of water up to 2 hours before anesthesia.

Routinely used medications have many potential interactions with drugs used during surgery. Meaning what?

The ½ life and adjustment of the dose according to the perioperative schedule must be considered.

T/F Anticholinergics are ineffective and increase risk of aspiration risk in surgery?

True

When do diabetics go back to their regular medication pattern?

● Restart regular regimen when patient is eating.

Laboratory monitoring of LMWH is only needed in those receiving prolonged treatment or in high-risk patients with a propensity for bleeding or recurrent thrombosis. Its effect can be monitored by heparin assay (antifactor Xa heparin assay, reference range 0.35-0.7 U/mL). When the diagnosis of DVT is made postoperatively, begin full-dose of what?

heparinization (bolus of 5000-10,000 IU, followed by continuous infusion of 1000-1500 IU/h) if surgical hemostasis is achieved. If a risk is still present, an inferior vena cava filter must be placed. Once on therapeutic heparin (aPTT of 1.5-2), warfarin should be initiated and the dose adjusted to maintain an appropriate INR (ie, 2-3). Heparin and a therapeutic level of warfarin should overlap for at least 48 hours before discontinuing heparin. The patient should remain on bed rest for 2-3 days to allow fixation of the clot to the vessel wall. Administer 3-6 months of therapy for proximal DVT, assuming that surgery was the only predisposing risk factor. LMWH may also be used in conjunction with warfarin for therapy of DVT.

What should be done for patients on quinidine and procainamide for arrhythmias?

should receive their dose on the night before surgery and restarted immediately post op.

What should the patient who is taking replacement thyroxine do before surgery?

take the medication in the perioperative period. Start the drug once patient is on oral liquids. This medication can be held 7 days due to long half life. ● Do not delay urgent surgery in a newly diagnosed hypothyroid patient.

● Patients with diabetes are at higher risk for perioperative complications. What should be their BG the morning of surgery?

● The blood glucose on morning of surgery ideally shoud be lower than 200mg.

What should be done for those with an ambulatory surgery who are on steroids perioperatively?

○ Administer hydrocortisone (100 mg IV/IM) at discharge, along with a prescription for a rapid taper of prednisone or resumption of the previous steroid dose. ○ A patient taking a high dose of steroids for immunosuppression should be maintained during the perioperative period. ○ Remember that when calculating the hydrocortisone dose, prednisone is 4 times stronger.

Patients treated with psychotropic drugs may have altered responses to other medications. With proper precautions, psychotropic drugs can be managed safely in surgical patients. Such *as with benzodiazepines. How so?*

○ Benzodiazepines (BZs) are the most commonly prescribed class of anxiolytic drugs and play a major role in anesthesia. They can be used throughout the perioperative period to treat anxiety and agitation. They can also be used with opiates for premedication or analgesia. ○ Patients who have been on BZs for a long time develop tolerance and have an increased risk of serious withdrawal symptoms. Maintaining these patients on BZs in adequate doses and appropriate formulations at timely intervals is indicated to avert withdrawal in the perioperative period. ○ The use of phenothiazines, butyrophenones, and BZs can lead to problems with hypotension and myocardial depression in the perioperative period in patients with heart disease. The recommendation is to discontinue tranquilizing agents several days before surgery and resume as needed on the second or third postoperative day.

A risk score for predicting postoperative nausea and vomiting after inhalation anesthesia identified 4 risk factors:

○ Female sex, ○ Nonsmoking ○ Prior history of motion sickness or postoperative nausea ○ Use of postoperative opioids.

A patient receiving corticosteroids within 3 months of surgery will have some degree of hypothalamic-pituitary-adrenal axis suppression and should receive perioperative supplementation. How does this affect minor and major surgery?

○ Minor surgery, in a patient on more than 10 mg/d of prednisone, 25-100 mg of hydrocortisone at induction is sufficient. Postoperatively, patients resume the usual dose of corticosteroid the next day. ○ Major operation: 100 mg of hydrocortisone every 8 hours for 24 hours should be used, on the day of surgery, then the dose of prednisone should be decreased rapidly (ie, 50% per day, down to the usual steroid dose). Oral corticosteroid therapy should be resumed when GI function returns.

Patients treated with psychotropic drugs may have altered responses to other medications. With proper precautions, psychotropic drugs can be managed safely in surgical patients. Such *as with antidepressants. How so?*

○ No drug interactions between selective serotonin reuptake inhibitors and anesthetics are known. ○ Tricyclic antidepressants (TCAs) manifest a number of important drug interactions. TCAs should be administered until just before surgery and resumed when the patient is able to take oral fluids. In cases in which the drug is to be discontinued, tapering should occur over 1-2 weeks to minimize sleep disturbances.

Patients treated with psychotropic drugs may have altered responses to other medications. With proper precautions, psychotropic drugs can be managed safely in surgical patients. Such *as with Lithium. How so?*

○ Treats bipolar affective disorders. It may potentiate the effect of depolarizing and competitive neuromuscular blocking agents. The clearance of lithium can be reduced and its toxicity increased by factors that cause negative fluid balance, negative sodium balance, and decreased glomerular filtration rate. ○ Lithium should be discontinued 2-3 days before major surgery and resumed when renal function and electrolyte levels are stable. If serum levels are not in a toxic range, renal function is normal, and fluid electrolyte status is stable, lithium can be continued before minor surgery.

Patients treated with psychotropic drugs may have altered responses to other medications. With proper precautions, psychotropic drugs can be managed safely in surgical patients. Such *as with Neuroleptic drugs. How so?*

○ Treats psychotic symptoms (phenothiazines, butyrophenones, thioxanthenes, indolones, and dibenzoxazepines.) ○ Most adverse effects of these drugs are easily managed. Given the complications associated with untreated psychosis in the perioperative period, continued treatment with antipsychotic drugs is warranted throughout the perioperative period.

What is key to in treating a pt with a heart valve prostheses and is on warfarin (Coumadin)?

● Anticoagulation is key ● For major surgeries substituting heparin for warfarin to maintain anticoagulation until the time of surgery. The short half life of heparin allows the patient to safely undergo surgery within in 6 hours after stopping heparin and then restarted 12-24 hours after surgery (when postoperative hemorrhage is no longer a threat. ● Monitor heparin by maintaining partial thromboplastin time (aPTT) of 1.5 - 2 times normal. ● For patients on warfarin check PTT 1 day before operative and administer vitamin K (1-3 mg) if necessary. ● Therapeutic anticoagulation is not typically reached for several days after starting warfarin again therefore a patient should received heparin until INR reaches desired levels ● For minor surgeries (cataract removal or dental procedures) coumadin does not need to be stopped.

How do you prevent hypertension perioperatively and manage it after surgery?

● Appropriate perioperative management of pain, anxiety, hypoxia, and hypothermia is key to maintaining normotension. ● If hypertensive postoperative restart patient's oral medications and minimize oral and IV sodium when possible. ● For patients with postoperative hypertension but unable to take oral meds treat with IV beta blockers (Propranolol, atenolol, or metoprolol. ● For serious hypertension vasodilators such as nitroglycerin and nitroprusside are appropriate

Other drugs for prophylaxis in the prevention of DVT?

● Dalteparin (Fragmin) is administered at 2500 U subcutaneously 1-2 hours before surgery and once daily postoperatively for moderate-risk patients. A dose of 5000 U with the same schedule is administered to high-risk patients. ● Tinzaparin is administered at 3500 U subcutaneously 2 hours before surgery and once daily postoperatively for moderate-risk patients. ● Fondaparinux sodium (Arixtra) is administered at 2.5 mg subcutaneously starting 6 hours postoperatively and once daily thereafter for moderate- and high-risk patients.

Administer all antihypertensive medications except diuretics and ACE inhibitors until when?

● Diuretics should NOT be administered day of surgery due to volume depletion and alterations in potassium ● The Renin angiotensin-aldosterone system is involved in maintaining normal blood pressure during anesthesia. Hemodynamic instability and refractory hypotension have been described with ACE inhibitor use. Stop ACE inhibitors the day before surgery.

● Beta-agonists and bronchodilators should not be discontinued in patients with asthma ● Beta agonists and atropine analogs should not be discontinued in patients with chronic obstructive pulmonary disease. What adjustments should be made?

● During surgery while the patient is under anesthesia these medications are not normally needed. ● Following surgery if they still have an ET tube inhaled medications can be continued. ● Some patients require increases in their steroid dose 1-2 weeks postoperatively. ● Postoperative analgesia can cause respiratory depression. Instruct pt to breathe deeply and cough to avoid atelectasis ● At time of discharge counseling counsel patient on the effects of smoking and urge them to stop ● Patients should be urged to stop smoking 1-2 months to receive benefit. When a person who smokes stops for a short time before surgery the use of transdermal nicotine replacement is helpful to alleviate withdrawal symptoms. ● For patients on long-term steroid therapy, increase the dose on the day of surgery (hydrocortisone 100mg q8h x 24 hours, then decrease dose by 50% every day until back to usual dose.)

Drugs in Rheumatic Disease like Methotrexate may increases the risk of postoperative complications (eg, infections, poor wound healing) and it is renally excreted. Thus how is it managed?

● Hold the drug 48 hours before surgery or any other procedure (eg, contrast dye study) that may be associated with even transient renal insufficiency is prudent. ● Some surgeons also prefer to withhold the drug for 2 weeks postoperatively to ensure appropriate wound healing. ● Depending on the severity of the rheumatologic condition, methotrexate should be started as soon as possible after surgery to avoid a rebound flare in arthritis. Discuss restarting all antirheumatic medications with the patient's rheumatologist.

When should you postpone an elective surgery in a diabetic patient?

● If glucose is >300mg.

What should be done for an emergency surgery for a diabetic?

● In emergency surgery, achieve optimal control rapidly and direct attention toward optimization of volume status. ● Intraoperatively maintain glucose levels of 100-200mg/dL.

● An intravenous dose of gastrokinetic agents are given at 5-10 mg usually 15-30 minutes before induction over 3-5 minutes to prevent abdominal cramping. ● An oral dose of 10 mg achieves onset within 30-60 minutes. ● Use is contraindicated in patients with bowel obstruction. Why is this done?

● It has no effect on gastric acid secretion. ● Gastrokinetic agents are used to reduce gastric fluid volume. ● Metoclopramide is a dopamine antagonist that stimulates upper gastrointestinal motility, increases gastroesophageal sphincter tone, and relaxes the pyloric sphincter.

What effects do Perioperative Nonsteroidal Anti-inflammatory Drugs have on the blood?

● NSAIDs inhibit platelet cyclooxygenase-1 (COX-1) blocking the formation of thromboxane A2, which impairs thromboxane-dependent platelet aggregation and variably prolongs the bleeding time. ● The inhibition persists for the circulating lifetime of the platelet.

● Give prophylactic antiemetic therapy when 2 or more of the risk factors are present when using volatile anesthetics. What meds are these?

● Ondansetron (4 mg IV), dexamethasone (4 mg IV), droperidol (0.625 mg IV), diphenhydramine (Benadryl) (25 mg IV), and scopolamine transdermal patch (1.5 mg) singly or in combination, are agents in common usage.[17] ● Antiemetics should be administered 30 minutes prior to the end of the case (except dexamethasone on induction and scopolamine patch preoperatively). ● Reduction risks, including avoidance /minimization of nitrous oxide, volatile anesthetics, high-dose neostigmine, and postoperative opioids.

What medication that women take is known to increased risk of postoperative venous thromboembolism because combined effects of hormones and the hypercoagulable state?

● Oral contraceptives ● Studies vary with recommendation. Discuss options of stopping medication 4-6 weeks before surgery or planning on thromboprophylaxis with LMWH. ● Always get a pregnancy test before surgery ● Women on hormone replacement will need thromboprophylaxis preoperatively

Patient populations at risk for postoperative nausea and vomiting include who?

● Patient populations at risk for postoperative nausea and vomiting include those scheduled for ophthalmologic surgery, patients with a prior history of nausea and vomiting or motion sickness, patients scheduled for laparoscopic surgery or gynecologic procedures, and patients who are obese.

● Grand mal seizures can increase the risk of surgery. If epilepsy has been controlled for 1 year blood levels of antiepileptic meds and EEG is not necessary. However, for those on Phenytoin and phenobarbital it should be continued in the perioperative period and managed how?

● Patients taking these drugs must be loaded with phenytoin at 18 mg/kg and maintained on 4-8 mg/kg in 3 divided doses until they resume eating. Those who are intolerant of or allergic to phenytoin may be loaded with phenobarbital in a dose of 6 mg/kg. ● Maintaining the serum levels in the upper half of the therapeutic range (ie, 15-20 mcg/mL for phenytoin, 30-40 mcg/mL for phenobarbital) minimizes the risk of intraoperative seizures. ● Phenytoin and phenobarbital are usually effective for all types of seizures except true absences, which require ethosuximide or valproic acid (not available in parenteral form). However, pure absence seizures pose little threat, and their treatment can be safely interrupted until after surgery.

What is required of people with type 1 diabetes in surgery?

● Persons with type 1 diabetes always require insulin perioperatively even if glucose is needed to prevent hypoglycemia. ● Monitor serum glucose every 1-2 hours during surgery and every 2-4 hours while NPO then administer short acting insulin as dictated by the sugar level.

What is required of people with type 2 diabetes in surgery?

● Persons with type 2 diabetes require insulin intraoperatively administered SQ at 50% the patients usual dose. If needed dextrose can be given along with insulin when patient is not eating (NPO). ● Monitor serum glucose every 1-2 hours during surgery and every 2-4 hours while NPO then administer short acting insulin as dictated by the sugar level.

Hypotension can occur at any time during surgery due to blood and fluid loss, effects of vasoactive anesthetic drugs. What drug can counter this?

● Phenylephrine is a selective alpha-1 adrenergic agent that causes peripheral vasoconstriction and can be used to treat hypotension associated with spinal anesthesia ● It also helps patients with CAD and aortic stenosis to increase coronary perfusion. ● Dobutamine is a B-adrenergic agent with minimal alpha-adrenergic agonist activity it is used to treat cardiogenic shock. It increases cardiac output and increases total peripheral resistance.

Patients with large gastric fluid volumes, nonfasting patients, obese patients, patients with trauma, and patients with hiatal hernia or history of gastroesophageal reflux are at risk for aspiration pneumonitis. Thus what is used to avoid aspiration and pneumonitis?

● The histamine receptor antagonists (H2 Blocker) cimetidine, ranitidine, famotidine, and nizatidine reduce gastric acid secretion via competitive antagonism of the histamine receptor, thereby increasing gastric fluid pH. These agents may be used for the allergic patient or in preparing a patient for exposure to an allergenic trigger, such as radiologic dye. ● Antacids are used 20-30 minutes before induction to increase gastric fluid pH higher than 2.5. The nonparticulate antacid, 0.3 M sodium citrate, is used because aspiration of gastric contents containing these antacids will not cause damage to lungs. In contrast, aspiration of gastric fluid containing particulate antacids may lead to pulmonary damage, despite the increase in gastric fluid pH. ● Proton-pump inhibitors suppress gastric acid secretion in a dose-dependent manner by binding to the proton pump of the parietal cell. Intravenous doses of 40 mg 30 minutes before induction are commonly used. Unfortunately, investigators have found increases in gastric pH and inconsistent effects on gastric volume with administration of omeprazole and ranitidine.

● The CDC define SSI as an infection that occurs at or near the surgical incision within 30 days postop. What is done to prevent this?

● Timing of prophylactic antibiotic administration and the choice of appropriate perioperative antibiotics are key to preventing SSI ● Time of drug administration is crucial. The first dose is always given before incision. The intraoperative dose is given ideally within 30 minutes and definitely within 2 hours of incision. ● Redosing of antibiotics during surgery based on ½ life, fluid administration, and blood loss is more important than continuation of the antibiotic after the wound is closed. ● Prophylaxis implies discontinuation of antibiotic within 24 hours for non cardiac surgery and 48 hours with cardiac surgery ● This will also prevent side effects and drug resistance

What are risks that come along with surgery on a hypothyroid patient?

● Watch for hypothermia, hypoventilation, hyponatremia, and hypoglycemia ● In patients with severe hypothyroidism can be given IV L-thyroxine. Elective surgery should be delayed in this patient.