Monday, May 10, 2021

Postoperative Care in the ICU Case File

Posted By: Medical Group - 5/10/2021 Post Author : Medical Group Post Date : Monday, May 10, 2021 Post Time : 5/10/2021
Postoperative Care in the ICU Case File
Eugene C. Toy, MD, Manuel Suarez, MD, FACCP, Terrence H. Liu, MD, MPH

Case 40
An 81-year-old man with an extensive past medical history including hypertension, type II diabetes mellitus, COPD, and gout was admitted to the hospital with microcytic anemia, and signs and symptoms of large bowel obstruction. The patient has lost approximately 10 lb (4.5 kg) over the past 1 month. A colonoscopy revealed an obstructive carcinoma in the descending colon. The patient subsequently under
went an exploratory laparotomy and left colectomy. He is admitted to the ICU approximately 4 hours postoperatively.

How would you optimally manage this patient's fluid status?
How would you address the patient's nutritional status at this time?
What are the possible complications related to his surgical disease processes, and how would you monitor and identify them?


ANSWER TO CASE 40:

Postoperative Care in the ICU

Summary: An 81-year-old man has an obstructing carcinoma in the descending colon. The mass was removed by an open left colectomy. The patient has extensive multiple medical comorbidities and is admitted to the ICU for close postoperative monitoring and management.

Management of fluid status: This patient needs cautious balance of his fluid status given his age and medical problems. Careful monitoring of urine output via Foley catheter and intravascular status with central venous pressure measurements will help guide management.

Nutritional status: The patient should be allowed to resume oral intake as soon as possible, generally within 48 hours postoperatively if tolerated. If the patient is unable to take in adequate calories orally, he may require supplemental enteral nutrition.


Possible complications: The approach to monitoring and identification: 

  • Cardiac: Myocardial infarction, atrial fibrillation, other cardiac arrhythmias identified by clinical examination, cardiac monitoring/ECG. 
  • Respiratory: Pulmonary edema, atelectasis, COPD exacerbation, acute respiratory distress syndrome (ARDS)-identified by clinical examination, CXR/chest CT, oxygen saturation, arterial blood gas. 
  • Fluids/electrolytes/nutrition: Third-space fluid shifts, stress- induced hyperglycemia, and poor nutritional status-identified by clinical examination, laboratory workup. 
  • Gastrointestinal: Surgical anastomostic leak, ileus, mechanical bowel obstruction identified by clinical examination, imaging studies, laboratory workup 
  • Genitourinary: Pre-renal azotemia, acute kidney injuries, and post-renal obstructive processes-identified by clinical examination, laboratory workup, imaging studies. 
  • Endocrine: Insulin-resistance, adrenal insufficiency-identified by clinical examination, laboratory workup. 
  • Hematologic/infectious: Anemia, wound infection, systemic inflammatory response syndrome (SIRS), sepsis-identified by clinical examination, laboratory workup. 
  • Musculoskeletal: Gout flare-identified by clinical examination.
ANALYSIS

Objectives
  1. To learn the common complications that may develop in the postoperative patients.
  2. To learn the disturbances produced by operative stress.
  3. To learn patient assessment, risk stratification, and risk-reduction strategies in the preoperative and perioperative settings.
Considerations
This patient has a descending colon cancer with anemia and large bowel obstruction. Large bowel obstruction from a mechanical cause has a poorer prognosis and higher morbidity since an emergency operation is needed. Additionally, the patient is already nutritionally depleted from the obstructive mass in the intestine as well as from weight loss from malignancy. The added stress of operation will increase his baseline energy expenditure and his nutritional requirements. Attention must be paid to the patient's fluid status as postoperative shifts will place stress on the cardiovascular and pulmonary systems, which are likely already affected by the patient's history of hypertension, anemia, and COPD. The presence of type 2 diabetes may mean that some degree of renal insufficiency is present and that there may be an increased risk for infection. An acute flare of gout is possible from the catabolic state after surgery or as a result of the fluid shifts caused by surgery. To minimize this patient's postoperative complications and facilitate his postoperative recovery, meticulous ICU care will be important to monitor several important organ system functions.

Approach To:
Postoperative Patients in the ICU

DEFINITIONS

CENTRAL VENOUS PRESSURE: The pressure in the superior vena cava, measured with a central venous catheter inserted into the internal jugular or subclavian vein. This estimates the right atrial pressure, reflecting the amount of the blood in the venous system returning to the heart.

ATELECTASIS: Collapse of lung alveoli or fluid consolidation that prevents effective gas exchange where the alveoli are deflated. This can affect varying proportions of the lungs and is commonly seen after injury or surgery, especially if breathing is restricted by pain or fatigue.

PULMONARY EDEMA: Fluid accumulation in the lung parenchyma either due to the inability of the heart to adequately remove fluid from the lung circulation (cardiogenic) or due to lung parenchyma injury (noncardiogenic). It can be caused iatrogenically by over-infusion of intravenous fluid.

ACUTE RESPIRATORY DISTRESS SYNDROME: Inflamed lung parenchyma associated with a systemic inflammatory response causing severe hypoxemia, often requiring mechanical intubation. It may be present by itself or as part of the multiple organ dysfunction syndrome (MODS). ARDS is defined as an acute process with a ratio of arterial partial oxygen tension (PAO2) to fraction of inspired oxygen (FIO2) <200, with bilateral infiltrates on chest x-ray, in the absence of elevated cardiac filling pressures.

THIRD SPACE FLUID LOSS: During inflammation, sepsis, or shock, fluid can be sequestered in extravascular spaces as proteins and fluid move to interstitial compartments, depleting intravascular volume. Examples include pulmonary edema, bowel wall edema, and fluid forced into the bowel lumen in cases of obstruction and retroperitoneal fluid sequestration with pancreatitis.


CLINICAL APPROACH

The intensive care providers in the ICU need to be familiar with the complications related to procedures, surgical diseases, and operative stresses. Understanding of these issues is critical for the anticipation and treatment of complications, addressing the needs of the postoperative patients, and optimizing communications between the intensive care providers and the surgical specialists. Postoperative problems can range from being relatively minor to life threatening. It is important for the clinician to be aware of the complications that can occur and to be vigilant about looking out for those that can cause serious morbidity and even mortality. The most important aspect to remember about postoperative complications is that complications in the postoperative patients are nearly always related to the operative procedures (known complications of the procedures and/or underlying disease conditions that necessitated the operations, and/or complications related to the exacerbation of 1 or more of the patient's comorbid conditions). The various systems that can be affected by surgical stresses are listed later.

Complications Categorized by Systems
Cardiac complications include acute coronary syndrome, myocardial infarctions, cardiac arrhythmias, and congestive heart failure. The increased stress on the heart increases the risk for myocardial infarction. Arrhythmias such as atrial fibrillation often occur due to fluid shifts throughout the body after an operation, placing more stress on the atria of the heart. These fluid shifts can also cause or worsen congestive heart failure.

Pulmonary complications can be closely linked to cardiac dysfunction in which the ability to adequately distribute intravascular fluid may be lost, causing a backup of fluid in the lungs, as in the case of pulmonary edema. Other common pulmonary complications include atelectasis, pneumonia, ARDS, and exacerbation of any underlying lung disease, such as COPD or emphysema.

Renal complications mainly present as oliguria, or low urine output. Acute kidney injuries can be classified into pre-renal, renal, and post-renal categories. Pre-renal causes are due to hypoperfusion of the kidney as seen in dehydration, fluid losses from vomiting/diarrhea, or as a result of an operation, poor intake or inadequate repletion, and cardiogenic shock or significant blood loss. Insensible fluid losses are increased during an operation, especially if the abdomen is left open postoperatively.

Bowel obstruction causes third spacing, further reducing intravascular volume. Renal causes of oliguria are from damage to the kidney itself, such as acute tubular necrosis from ischemia or medication toxicity. Post-renal causes are due to obstruction of urine flow, such as Foley catheter blockage, prostatic hypertrophy or compression from tumor, hematoma, or fluid collection. If the FENa ( fractional excretion of sodium) is < 1 along with other signs that the body is trying to retain water (high serum osmolality, low urine sodium), this indicates a pre-renal state whereas proteinuria and cells or casts on urinalysis may point toward direct renal damage or ATN. Causes of post-renal (obstructive) oliguria can usually be found via physical examination or imaging.

Fever can be a sign of complications and can be divided into 3 categories based on timing. Immediately postoperative fever (< 24 hours) may be a response to surgery or atelectasis, although in some cases a necrotizing wound infection (Clostridium or group A Streptococcus) can be the cause. Fevers occurring from 24 to 72 hours may be residual atelectasis but should prompt a search for other sources of infection such as pneumonia, urinary tract infections (especially if a Foley catheter is in place), or IV line infection/phlebitis. After 72 hours, fever is likely due t o the infectious sources mentioned above or wound infections, deep internal abscesses, anastomotic leaks, prosthetic infections, or deep vein thrombosis. Rarely, entities such as acalculous cholecystitis, most often seen in critically ill patients, can also be a cause of fever. The workup includes physical examination of the patient, the incision site, and any IV lines or catheters as well as blood, sputum, urine, and wound cultures. Imaging may be helpful. For example, a chest x-ray may reveal a pulmonary consolidation in pneumonia or an effusion, a Doppler ultrasound of the legs or chest CT may identify a DVT or pulmonary embolus, or an abdominal CT scan may find a deep abscesses. Appropriate treatment depends on the cause, varying from incentive spirometry and mobilization for atelectasis to removal of catheters and IVs, antibiotics, and operative drainage of deep abscesses if necessary.

Wound complications may occur in any patient although appropriate preoperative antibiotics, meticulous operative technique, and hemostasis are the most effective prevention. There is no additional benefit in the extension of prophylactic antibiotics beyond the immediate postoperative period. High-risk patients for wound complications are individuals with contaminated surgical fields, impaired blood flow to healing tissues from hypotension, diabetes, obesity, or smoking, and those who are immunocompromised. Wound complications include hematomas and seromas, infection in either superficial or deep spaces, and fascial dehiscence or incisional hernias. Wounds or hematomas/seromas that appear infected (tenderness, erythema, purulence) should be opened, drained, and packed loosely. Extensive wound dehiscence at the fascial level may require repair in the operating room. Close communication between the intensive care provider and the surgeons are critical for the management of wound-related complications.

Neurologic complications after operation are often related to the treatment of postoperative pain. While hypoxemia and stroke can cause neurological changes, electrolyte abnormalities and medications are also common causes. Medications for treatment of pain, including opiates, and sedatives in critically ill patients may cause delirium, agitation, and somnolence. Elderly patients tend to have greater susceptibility to these effects. Patients in the ICU may also experience delirium, ICU psychosis or "sundowning," which may be brought on by fragmented sleep patterns, disturbances in the day-night cycles, and loss of familiarity with one's surroundings.


Disturbances Produced by Operative Stress on the Various Systems

Cardiovascular: Due to increased postoperative metabolic demands, cardiac output increases, leading to higher oxygen requirements of cardiac myocytes. Operative stress coupled with hypovolemia, infection or traumatic injury, as well as any anesthetic or vasoactive medications, may prevent the patient's cardiovascular system from fully compensating for the increased demand, leading to myocardial ischemia, infarction, fluid overload, cardiac failure, and arrhythmias. Despite the increased cardiac demands, recent data suggest that postoperative acute coronary syndrome is just as likely to be produced by coronary artery plaque instability and rupture, which is believed to be due to increased catecholamine and inflammatory mediators' responses in the postoperative period.

Pulmonary: Oxygen consumption demands are increased postoperatively due to increased metabolic demands. Ventilation and oxygenation problems in the postoperative period may arise from the combination of increased O2 demand and compromised vital capacities. For example, upper abdominal and thoracic incisions significantly decrease the patients' vital capacities secondary to pain associated with the respiratory effort; this can then result in subsequent atelectasis and increased risk for pneumonia. Decreased mentation following general anesthesia and/or sedation medications may increase patients' susceptibilities for pulmonary aspirations. Lung parenchymal injuries may develop following systemic inflammatory response, leading to acute lung injury (ALI) and ARDS. Surgical stresses and immobility render the patients susceptible to venous thromboembolic complications. Conditions such as asthma or COPD can be exacerbated postoperatively and require treatment with steroids and/or bronchodilators.

Metabolic: The patient' metabolic responses to surgery are variable and are related to the type and magnitude of the surgical stresses. Conditions such as trauma, sepsis, and burns further contribute to the increase in metabolic demands. Critically ill patients have accelerated breakdown of muscle protein for the reprioritization of acute-phase protein synthesis. Hyperglycemia in the postoperative patient is common and is caused by both increase in glucose production by the liver and decrease in uptake of glucose by insulin-dependent tissues. Untreated hyperglycemia contributes to glycosuria, excess fluid losses, and impairment of leukocyte function leading to infections. Glucose monitoring and treatment with insulin are essential in the postoperative patients. Insufficient adrenal functions can be exacerbated by surgical stresses and/or sepsis. This may be manifested by hypotension that is unresponsive to standard fluid administration. In some instances, adrenal dysfunction can manifest as unexplained fever, hypoglycemia, confusion, lethargy, and abdominal pain. By far, the most common reason for adrenal insufficiency is iatrogenic. A patient with long-term steroid medication use history is vulnerable to the development of adrenal insufficiency in the face of surgical stress, sepsis, or trauma.

Gastrointestinal: Patients who are not intubated can be expected to resume oral intake shortly after an operation. While the traditional practice is to maintain a nil per os (NPO) policy until there is return of bowel function documented by passage of flatus or bowel movement, a growing body of literature suggests that there are potential benefits to reinstating some form of oral intake within 48 hours of operations in patients who can tolerate it. In patients who are intubated and/or those who are not expected to take in adequate oral calories for prolonged periods of time, supplemental nutrition via enteral tube should be anticipated and implemented. Operative manipulation of the bowel and medications for pain can contribute to ileus and delayed GI functions. Narcotics can contribute to constipation and fecal impaction. It is possible for adhesions to form and bowel obstructions to occur within days after surgery, although most obstructive complications secondary to adhesions occur later. Critically ill patients are also at risk for stress ulcers, where hypoperfusion, loss of host gastric barrier functions, and gastric acidity can produce mucosal injuries. ICU patients in shock, sepsis, respiratory, hepatic, renal, or hematologic failure are benefited by stress ulcer prophylaxis with H2-antagonists or sucralfate.


Perioperative Assessment, Risk Stratification, and Risk Reduction

Patient assessment: Many healthy patients are able to undergo operative procedures uneventfully. However, those who are medically compromised require more careful pre- and perioperative evaluations to assess for fitness for surgery and ensure favorable outcomes.

Several methods are commonly used to assess patients' medical status prior to an operation. The American Society of Anesthesiologists' (ASA) classification is based on the patient's condition where Class I patients are healthy, Class II have mild systemic disease, Class III have severe systemic disease which limits activity but is not incapacitating, Class IV is incapacitating systemic disease which is a constant threat to life, Class V is a moribund patient not expected to survive 24 hours with or without operation, and Class VI is an organ transplant donor. The designation of "E" is added to any class if the case is an emergency. Goldman calculated a cardiac risk index in which a varying number of points is awarded for clinical factors present, with 11 points for an S3 gallop/JVD and 10 points for a myocardial infarction within 6 months as the 2 biggest contributors to cardiac risk. The highest risk (Class IV) patients had a 22% incidence of major cardiac complications and a 56% mortality rate. More recently, Lee developed the Revised Cardiac Risk Index in which 6 independent predictors of perioperative cardiac complications were established ischemic heart disease, congestive heart failure, cerebrovascular disease, diabetes requiring preoperative insulin treatment, serum creatinine >2.0 mg/dL, and whether
the patient was undergoing a high-risk operation. A high-risk operation includes intraperitoneal, intrathoracic, or suprainguinal vascular (such as aortic) operation.

Risk stratification: Preoperative evaluation provides the anesthesia and surgical teams' information regarding the patient's current medical status, risk profile, and recommendations for management during the perioperative period. Tests should only be ordered if the results could change the treatment and management plan. Examples include an electrocardiogram, or a cardiac stress ECG to examine the patient's cardiac response to increasing oxygen demand with exercise or dipyridamole-thallium scanning for those patients unable to exercise. Echocardiography gives an analysis of ventricular wall motion, ejection fraction, and ventricular hypertrophy. Pulmonary function tests are useful i n patients who may need to undergo lung resection. On admission t o the ICU, the APACHE (acute physiology and chronic health evaluation) score may be used to risk-stratify patients, and it is calculated from 12 different physiological measurements. Although it is used for risk stratification and to compare the morbidity of patients, due to its complexity it is cumbersome to use.

Risk reduction: The ultimate goal of pre- and perioperative assessment is to optimize patient outcome. Patients may certainly benefit from having their medical comorbidities optimized preoperatively; examples include controlling hypertension, cardiac arrhythmias, and diabetes before surgery. Improving the patient's preoperative nutritional status is also important. Percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) have not been shown to be effective in reducing perioperative cardiac morbidity except perhaps in patients with left main coronary artery disease. The use of β-blockers in at-risk patients has been shown to reduce the risk of perioperative cardiac ischemia and death, but the timing of stopping the β-blocker postoperatively remains controversial. If the patient does not have an emergency condition, a preoperative workup may elucidate a need to modify the original anesthetic or operative plan and defer or change the operative approach. Intraoperative risk reduction strategies include keeping the patient warm, maintaining euglycemia, administration of perioperative antibiotics within an hour of skin incision, and sequential compression devices for prevention of DVT. Postoperatively, patients should be have continued DVT prophylaxis with sequential compression devices (SCDs), heparin, or low molecular weight heparin until they are able to mobilize, as well as oral hygiene, aspiration precautions, incentive spirometry to prevent atelectasis and pneumonia, frequent turning to prevent pressure sores, and ulcer prophylaxis if indicated.


CLINICAL CASE CORRELATION
  • See also Case 3  (Scoring Systems and Patient Prognosis), Case 8  (Airway l Management), Case 14 (Acute Coronary Syndrome), Case 23 (Acute Kid­ney Injury), and Case 33 (Multiorgan Dysfunction).

COMPREHENSION QUESTIONS

40.1  A 92-year-old woman underwent a laparoscopic cholecystectomy for cholecystitis. She had some mild hypotension to the 80/40 mm Hg range postoperatively and received fluid resuscitation. Her weight is 45 kg. Which of the following findings are most consistent with inadequate resuscitation?
A. Urine/serum creatinine ratio of 45
B. CVP of 13 mm Hg
C. Urine output of 25 mL in the last hour
D. Bilateral pulmonary crackles on auscultation
E. Fractional excretion of sodium of 1.3%

40.2 A 78-year-old patient develops a temperature of 101.4°F 2 days after undergoing an elective right hemicolectomy for a small, nonobstructing cancer that was found on colonoscopy. Which of the following is the least likely cause of her fever?
A. Pneumonia
B. Urinary tract infection
C. Atelectasis
D. Wound infection
E. Intra-abdominal abscess

40.3  A 34-year-old obese man underwent an emergency midline laparotomy after sustaining a gunshot wound to the abdomen. A short segment of small bowel was resected due to damage from the bullet. Several days later, the patient has made a good recovery. However, when he stands to walk to the bathroom, he experiences a large gush of serosanguinous fluid from his abdominal wound. Examination of the wound shows a 4-cm fascial dehiscence. The most appropriate management is:
A. Reapproximation of the wound with sterile tape
B. Abdominal binder and placing the patient on bed rest
C. Further opening of the wound to allow adequate drainage and packing with gauze
D. Return to operation room for repair
E. Culture of the wound fluid and antibiotic treatment

40.4  A 55-year-old patient has hypertension that is controlled with hydrochlorothiazide and metoprolol. What is his ASA classification?
A. I
B. II
C. III
D. IV
E. V

40.5  A 68-year-old patient who has a history of insulin-dependent diabetes and stable angina takes chronic steroids for rheumatoid arthritis, and has a history of colonic diverticuli. She underwent an emergency diverting colostomy for perforated diverticulitis with fecal spillage, remains intubated in the ICU, and is on broad-spectrum antibiotics. Two days postoperatively, she becomes acutely febrile to 102.6°F with confusion and lethargy. Her heart rate is 110 beats/minute with a blood pressure of 79/58 mm Hg. She remains hypotensive despite starting on fluid resuscitation and vasopressors. Her laboratory tests show a glucose of 46 mg/dL. What is the most likely cause of her clinical picture?
A. Myocardial infarction
B. Diabetic ketoacidosis
C. Hypovolemia
D. Adrenal insufficiency
E. Sepsis


ANSWERS TO QUESTIONS

40.1  A. In a hypovolemic patient, the CVP would be low (< 5), she would not have bilateral crackles suggestive of pulmonary edema, and the fractional excretion of sodium would be < 1%. Although a urine output of 25 mL may seem low, for a patient weighing only 45 kg, 0.5 mL/kg/h equals an expected urine output of 22.5 mL/h. The kidney would be trying to retain volume so the urine sodium would be low (<20 meq/L), the serum osmolality would be high ( >500 mOsm/kg), and the urine/serum creatinine ratio would be >40. Thus, the urine to serum creatinine ratio of 45 in this patient indicates a "prerenal" picture of hypovolemia.

40.2  E. The patient has developed a fever within 72 hours of undergoing surgery. This may still be due to atelectasis if the patient is not expanding her lungs well due to being in bed or to pain. However, infectious sources may be the culprit by this time frame. Pneumonia, urinary tract infection, wound infection, and IV line infections may all be possibilities. Intra-abdominal abscesses generally take a few more days to form and are less likely at this relatively early time point.

40.3  D. This patient has experienced a fascial disruption with the serosanguinous fluid coming from the peritoneum. Because the dehiscence is larger than just 1 or 2 cm, the patient is at high risk for infection and evisceration as well as a ventral hernia. Prompt operative repair will minimize these risks and allow the patient to recover and resume normal activity sooner.

40.4  C. Hypertension is classified as a systemic disease. The patient requires medication to treat his disease, which makes his condition more serious than a Class II. However, his hypertension is controlled on his medications, so he is ASA Class III rather than Class IV.

40.5  D. Acute adrenal insufficiency often presents as unexplained fever, persistent hypotension, mental status changes, and hypoglycemia. This presentation can be similar to sepsis but sepsis tends to present with hyperglycemia in its early stages. While the etiology of adrenal insufficiency can be primary in nature, abrupt cessation of steroids is the most common cause. Treatment consists of IV fluids and hydrocortisone 100 mg IV for adrenal crisis, with steroid taper as tolerated as the crisis resolves.


CLINICAL PEARLS

 Most postoperative complications are related to the surgery or the under­lying diseases that led to the operation. 
 Risk assessment in the preoperative setting help identify patients that are at risk for specific complications and provide opportunities for the implementation of risk-reduction strategies. 
 Older age  and preexisting conditions contribute to reduced functional reserve and increased susceptibility to injury-induced organ dysfunctions. 

References

Fleisher LA. Cardiac risk stratification for noncardiac surgery: update from the American College of Cardiology/American Heart Association 2007 Guidelines. Cleveland Clin] Med. 2009;76(suppl 4 ): S9-S15. 

Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation. 1999;100:1043-1039. 

Marquardt DL, Tatum RP, Lynge DC. Postoperative management of the hospitalized patient. In: Souba WW, et al, eds. ACS Surgery: Principles and Practice. 6th ed. Philadelphia, PA: Decker Publishing, 2007. 

Walsh F, Ali J. Chapter 88. Preoperative assessment of the high-risk surgical patient. In: Hall JB, Schmidt GA, Wood LDH, eds. Principles of Critical Care. 3rd ed. http://www.accesssurgery.com/content. aspx?aiD=2296894, accessed July 2, 2013.

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