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Postoperative evaluation: Clinical practice

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Postoperative evaluation: Clinical practice

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A 22 year old male patient presents to the emergency room with 12 hours of severe hematemesis and hematochezia. The patient is stabilized in the ICU overnight and undergoes an upper endoscopy the following morning. Anesthesia is induced and maintained with midazolam and propofol. The patient is at aspiration risk, so he is intubated with succinylcholine used for neuromuscular blockade. 45 minutes later the procedure is complete, and anesthesia is stopped, but 5 minutes later the patient is not making any respiratory effort. Train of four monitoring reveals 0 out of 4 twitches. What is your next best step in the management of this patient?

Transcript

Content Reviewers:

Rishi Desai, MD, MPH

The goal of a postoperative evaluation is to recognize and manage issues that arise in the immediate postoperative period.

Generally, right after any procedure requiring anesthesia, individuals are monitored in a post-anesthesia care unit or PACU for things like respiratory distress or cardiac complications.

Signs of respiratory distress include tachypnea - with a respiratory rate over 30 breaths per minute, or bradypnea - with a respiratory rate below 8 breaths per minute; SpO2 lower than 93 percent; or in severe cases cyanosis and use of accessory respiratory muscles. If there’s a concern, an arterial blood gas and a chest X-ray can be obtained.

Also cardiac monitoring is done to assess their heart rate and blood pressure, because postoperatively, individuals are at increased risk of cardiovascular complications like hypo- or hypertension, cardiac arrhythmias, myocardial ischemia, and even heart failure.

Individuals are also assessed for their mental status, temperature, pain level, neuromuscular function, ability to pass gas and stool, and presence of nausea or vomiting.

Last but not least, a person’s hydration status along with intake and output - like fluid administration, urine output, bleeding, and wound drainage - are all carefully tracked. Now, the most common postoperative complication is nausea and vomiting.

Risk factors include preoperative nausea and vomiting, female gender, having a history of postoperative nausea and vomiting or motion sickness, use of volatile anesthetics, longer duration of anesthesia, and the type of surgery, with cholecystectomy, gynecologic, and laparoscopic procedures showing slightly higher risk compared with other general surgical procedures.

To help minimize this, inhalation agents which more commonly cause those symptoms, can be avoided.

Instead, total intravenous anesthesia or TIVA can be used along with propofol, which helps with induction and maintenance of anesthesia.

In addition, preventive measures include giving antiemetics like a scopolamine patch at least two hours prior to the induction of anesthesia and removing the patch within 24 hours.

Also dexamethasone - 4 to 8 milligrams can be given intravenously after induction, and this is thought to have a direct antiemetic effect, and help with postoperative pain. Finally ondansetron - 4 milligrams intravenously, can be given at the end of surgery.

After the surgical procedure, there is likely to be a lot of pain which can also worsen feelings of nausea and vomiting. Pain control that minimizes or avoids opioids is particularly important.

One option is 1 gram of IV acetaminophen or 15 to 30 milligrams of IV ketorolac, as well as local and regional anesthesia.

If there is nausea and vomiting postoperatively, individuals should get a rescue antiemetic that’s from a different drug class from ones used for prophylaxis, unless the first drug has worn off and the person is due for another dose.

Some options are 5 to 10 milligrams of IV prochlorperazine or 0.625 milligrams of IV droperidol.

Atelectasis is a common pulmonary postoperative complication in which there’s the collapse or closure of a lung, resulting in reduced or absent gas exchange, and it presents with shallow breathing, weak cough, and hypoxemia.

It is most common on days 2 to 3 following abdominal or thoracoabdominal surgery, and it’s usually caused by decreased compliance of lung tissue, impaired regional ventilation, retained airway secretions, or postoperative pain that interferes with spontaneous deep breathing and coughing.

For treatment, individuals without abundant secretions can get continuous positive airway pressure or CPAP, which delivers pressurized air or oxygen through a nose or face mask to help ensure that the alveoli do not collapse.

On the other hand, individuals with abundant secretions are treated with chest physiotherapy, focusing on deep breathing exercises and encouraging coughing, as well as oral suctioning for those who are unable to expectorate their secretions.

Prophylaxis for postoperative atelectasis includes smoking cessation at least 8 weeks prior to surgery, and preoperative exercise and pulmonary rehabilitation with aerobic exercises, deep breathing exercises, and inspiratory muscle training, as well as incentive spirometry, which is a medical device that measures how deeply an individual can inhale, and helps take slow, deep breaths to better expand the lungs.

Venous thromboembolism is an important and relatively common postoperative complication, since individuals are hypercoagulable and immobile.

This is particularly true in oncologic, pelvic, orthopedic, and neurosurgeries. Venous thromboembolism includes deep vein thrombosis and pulmonary embolism.

Symptoms can include leg swelling, pain discoloration, dyspnea, respiratory distress, hypoxia, syncope, and fever.

Diagnosis is usually done with duplex ultrasound, which identifies the presence, location, and extent of venous thromboembolism.

Usually when there’s venous thromboembolism, a d-dimer level is checked as part of a long-term treatment monitoring strategy as the levels tend to normalize with resolution of the clot.

Initial management of uncomplicated thrombosis is supportive, and consists of extremity elevation, warm or cool compresses, and NSAIDs.

In addition to supportive care, anticoagulation is given to most individuals without contraindications.

Initial anticoagulation therapy includes unfractionated heparin or low-molecular-weight heparin, subcutaneous fondaparinux, or novel oral anticoagulants like rivaroxaban or apixaban; and then bridging to long-term anticoagulation therapy with oral anticoagulants like warfarin or novel oral anticoagulants.

Prophylaxis of venous thromboembolism can be pharmacologic, or mechanical for individuals at high risk of bleeding or in whom anticoagulation is contraindicated.

Pharmacologic prophylaxis can be done with subcutaneous low molecular weight heparin, unfractionated heparin, or fondaparinux.

On the other hand, mechanical methods include intermittent pneumatic compression, graduated compression stockings, and venous foot pumps.

Moving on, there’s postoperative urinary retention,which is when the individual cannot fully empty their bladder, and may be characterized by a drop in urine output or an inability to void, and a feeling of discomfort or distension in the bladder.

Common causes are bladder dysfunction, urethral obstruction, or failure of pelvic floor relaxation.

It’s especially common in women after cesarean delivery done with epidural anesthesia, or individuals undergoing anorectal surgery, as well as individuals over 50 years, those with underlying neurologic disease, surgery lasting longer than two hours, use of more than 750ml of intraoperative fluid, and when anticholinergic medications like atropine, opioids, and spinal or epidural anesthesia have been used.

Now, in individuals who can’t void urine within four hours after surgery, the bladder volume has to be measured either with ultrasound or by draining the bladder with catheterization.

If more than 300 to 600 milliLiters is measured on ultrasound, or if there’s suspected inaccuracy of the ultrasound measurement - due to body habitus, tissue edema, or prior surgery with scarring, then a one-time bladder catheterization is done.

If the urine volume that’s drained in the first 10 to 15 minutes after bladder catheterization exceeds 400 milliLiters, the catheter can be left in place.

These individuals require bladder drainage and decompression with an indwelling catheter or clean intermittent catheterization to prevent overdistention injury, which occurs when the bladder is filled to greater than 120 percent of its regular capacity - which is about 400 to 600 milliLiters.

Bladder catheterization is typically done through the urethra however, in individuals who have had recent urologic surgery or trauma, or severe strictures, prostate enlargement or malignancy, urethral catheterization is contraindicated, so they should have suprapubic catheterization.

Clean intermittent catheterization is another option for bladder decompression, especially for outpatients who are comfortable with managing the catheter and individuals with acute-on-chronic urinary retention who are expected to require long-term catheterization.

Another postoperative issue is a paralytic ileus. That’s when the intestinal muscles fail to regain their motility after surgery, delaying or preventing the passage of gas or stool.

Other signs and symptoms may include abdominal pain, distention, bloating, nausea or vomiting, and a loss of appetite. A prolonged postoperative ileus is when it persists for more than four to six days.

Risk factors for a prolonged postoperative ileus include prolonged abdominal or pelvic surgery, open surgery, having surgery for Crohn’s disease or volvulus, and individuals with sepsis, ascites, advanced age, male gender, history of smoking and an increased body mass index.

Evaluation of a prolonged postoperative ileus includes plain x-rays or CT scan of the abdomen to ensure that there isn’t a small bowel obstruction or bowel perforation.

Supine and upright plain abdominal radiographs may show dilated loops of bowel in individuals with postoperative ileus, but should demonstrate air in the colon and rectum without a transition point between the dilated and non dilated bowel, which would indicate a bowel obstruction, and no evidence of free air to suggest perforation.

Treatment is supportive care, including pain control that minimizes opioids, IV fluid and electrolyte therapy, early enteral nutrition, and potentially treatment with coffee, chewing gum, prokinetic agents, and laxatives, to stimulate intestinal motility.

Placement of a nasogastric tube for gastrointestinal decompression is indicated for those with persistent nausea or vomiting.

Individuals should be closely monitored, with additional imaging if they don’t improve over 48 to 72 hours.

Another postoperative issue involving the gastrointestinal tract is acute colonic pseudo-obstruction, also known as Ogilvie’s syndrome, in which there’s massive acute dilation of the colon in the absence of any mechanical bowel obstruction.

The precise mechanism by which this occurs is unknown, but the association with trauma from surgery, spinal anesthesia, and pharmacologic agents suggests an impairment of the autonomic nervous system.

The main clinical feature is abdominal distension that usually occurs gradually over three to seven days. Individuals may also have abdominal pain, nausea, vomiting, constipation, or diarrhea.

Physical examination reveals a distended and tympanitic abdomen, and the diagnosis can be confirmed by abdominal imaging like x rays or CT scan showing a dilated colon and excluding a mechanical obstruction.

Individuals with Ogilvie’s syndrome are at risk of colonic ischemia and perforation, so they should be carefully monitored with serial physical examinations and x rays every 12 to 24 hours to evaluate the colonic diameter.

Treatment depends on the presentation, so conservative therapy with IV fluids and decompression with a nasogastric tube can be given to individuals without significant abdominal pain or extreme colonic dilatation - defined as dilation of more than 12 centimeters, which puts them at high risk of colonic perforation.

On the other hand, pharmacologic therapy with IV neostigmine is given to individuals with extreme colonic dilatation, or failure of conservative therapy after 24 to 48 hours.

Those who have contraindications to neostigmine or fail to respond may get colonoscopic decompression.

Finally, surgical decompression is the last resort for individuals who fail every other therapy option, as well as for management of those with colonic perforation.

Finally, both hypothermia and hyperthermia can occur in the immediate postoperative period.

Hypothermia occurs in nearly all individuals intraoperatively, and there are various perioperative warming strategies to help deal with this.

There are prewarming strategies - so before induction of anesthesia with an active forced-air warming blanket that uses convection to heat the individual and can be continued intraoperatively, conduction blankets that have been warmed or have warming elements in them, passive insulation with standard hospital cotton blankets; and intraoperative ways to actively warm the body like warmed IV fluids, warm inspired gases, use of circulating-water warming mattresses or garments, and maintaining the temperature of the operating room.

Postoperative temperature should be monitored, and individuals whose temperature hasn’t returned to normal should be actively rewarmed with a forced-air convection blanket, radiant heaters or warmed conduction blankets.

Now, it takes much longer to reheat an individual postoperatively, so it is ideal to use intraoperative thermoregulation strategies.

Perioperative hyperthermia is far less common than hypothermia. Causes include excessive perioperative heating, an acute transfusion reaction, an adverse effect of medication, an underlying medical condition, or a fever.

To manage hyperthermia, the first thing is to remove any sources of excessive heating, and to evaluate for other signs of a transfusion reaction or an adverse reaction to a medication.

If the source seems to be a fever, defined as 38 degrees celsius or 100.4 degrees Fahrenheit, then the timing of the fever is a big clue.

A fever is considered immediate if it begins in the operating suite or within a few hours of the surgery, acute if it begins within the first week after surgery, subacute if it begins one to four weeks after surgery, or delayed if it begins more than one month after surgery.

The most common causes of postoperative fever may be summarized by a mnemonic beginning with the letter W – Wind, Water, Wound, Walking, Wonder Drugs, and Waterway.