Multisystem Study Guide for the CCRN

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General Information

It’s unlikely that many critical care patients’ need for care involves only one body system. The questions in this content area (about 14% of the test) will require you to connect your knowledge of various systems and combine it to make crucial medical decisions, given a certain scenario. Check out the information in this study guide as you work through the material.

Acid-Base Imbalance

Patients with multisystem health concerns can develop acid-base imbalance. Acid-base imbalance can be respiratory or metabolic. Patients can also be acidic or alkalotic within those categories.

Respiratory acidosis and alkalosis are covered in the pulmonary section of the CCRN review. Metabolic acidosis and alkalosis will be covered within this section. For more guidelines regarding the lab values associated with with acid-base balance, please see our related blog.

Metabolic acidosis can be caused by tissue damage, kidney disease, lactic acid buildup, aspirin poisoning, diabetic ketoacidosis, and severe dehydration. Critical care patients are at particular risk for this imbalance due to gastrointestinal or renal bicarbonate loss and medications that cause hyperkalemia. Symptoms of metabolic acidosis include tachypnea, lethargy, and confusion.

Treatment of metabolic acidosis focuses on correction of any electrolyte and fluid imbalances. If acidosis continues despite these corrections, correction of the acidosis with bicarbonate may be needed.

Metabolic alkalosis occurs when there is an increase in sodium bicarbonate concentration in the blood. It is often associated with hypokalemia and can cause symptoms of lethargy, myalgia, weakness, arrhythmias, and polyuria. Hypoventilation, tetany, and seizures may also occur. Patients at risk for metabolic acidosis include those with vomiting or diarrhea, familial history of alkalosis, those with renal failure, and those with history of GI surgery such as an ileostomy. Diuretic use, excessive licorice consumption, tobacco chewing, glucocorticoids, antacids use, and calcium carbonate use can also cause metabolic alkalosis. Patients may also have conditions such as Cushing syndrome, bulimia, and congenital adrenal hyperplasia.

Treatment of metabolic alkalosis focuses on resolution of underlying conditions. If persistent vomiting is present, using antiemetics and correcting fluid imbalance (using 0.9% sodium chloride) should be considered. H2 inhibitors can be beneficial for critical care patients requiring continuous or intermittent gastric suction. Loop or thiazide diuretic therapy may be switched to potassium-sparing diuretics to reduce bicarbonate retention. Hemodialysis or peritoneal dialysis may be required, especially for patients with severe renal failure, if other treatment measures are inadequate in correcting the patient’s alkalosis.

Mixed acid-base imbalance can occur when either the respiratory or metabolic systems try to compromise for the acidity or alkalinity of the other. In order to identify if more than one acid-base imbalance is present, the anion gap should be measured.

Body Function and Regulation

Several traits can impact how a person responds to illness, injury, and therapy. Many adult patients experience one or more complications due to illness. Underlying conditions managed day to day may become uncontrolled in the event of an exacerbation. These can create difficult situations and make navigation of treatment more complicated. Reducing the number of factors that negatively impact a person’s health can provide improved outcomes in their return to health.

Bariatric Complications

According to the CDC, approximately 40% of all adults are considered obese. Obesity is defined as a BMI greater than 30. It is associated with numerous health problems, including delayed wound healing, improper storage of fat cells, respiratory complications, decreased immune function, decreased metabolism, strained mobility, and much more. It also carries a high risk for comorbid conditions either caused by or associated with the patient’s increased weight. These conditions include Type II diabetes mellitus, hypertension, hyperlipidemia, and atherosclerosis.

Bariatric patients in intensive care settings pose a greater risk of complicated medical needs than non-bariatric patients. Due to the excess weight, special accommodations may be needed to provide safe and comfortable beds with appropriate mobility assists. Bariatric patients are more likely to need oxygen support as their excess weight pushes on and prevents full diaphragmatic expansion. They must have specific dietary needs met to ensure they receive enough protein in their diet. Prevention of pressure ulcers and skin breakdown becomes essential to reducing overall medical complications due to delayed wound healing. Finally, psychological and psychosocial health should also be assessed, as many bariatric patients suffer from anxiety and depression due to negative body image.

Comorbidity in Patients with Transplant History

Patients who have undergone an organ transplant in the past are at high risk for comorbidities both prior to and following the transplant. Common comorbidities that occur prior to organ transplant include peripheral vascular disease, renal disease, hepatic disease, cardiac disease, respiratory compromise, diabetes, and obesity. Comorbidities that tend to appear after the transplant event include transplant rejection, immunosuppression, bleeding disorders, and medication complications/side effects.

Patients who have had an organ transplant will be prescribed numerous medications to reduce rejection of the transplanted organ and overall improve the patient’s quality of life. The medications do not come without risk, though, and can cause varying symptoms and chronic changes like fatigue, weight gain, immunosuppression, and bleeding. In some cases, long-term use of medications and immunosuppression may result in specific cancers such as lymphoma and Kaposi’s sarcoma.

One of the most common complications following organ transplant is graft vs. host disease. In this disease, the original body and immune system attack the foreign tissues, causing organ dysfunction and systemic changes. It may occur acutely or chronically. Common symptoms include skin rash, yellowing of the eyes, nausea, vomiting, diarrhea, abdominal cramping, and increased eye dryness/itchiness. Additional immunosuppressive and steroid medications may be used to minimize symptoms; however, symptoms may recur or persist despite the indicated therapy.


Hypotension is defined as a low blood pressure, usually less than a systolic blood pressure of 90 mmHg or diastolic pressure less than 60 mmHg. It can occur in critically ill patients and is usually a sign of worsening illness. Common causes of hypotension include sepsis, shock, bleeding, medication interaction, hypovolemia, heart failure, brain injury, and anaphylaxis. Hypotension needs to be recognized early to allow for proper management.

Patients with hypotension may experience several symptoms. Patients may have decreased urine output (oliguria) and acute renal failure. Patients may become delirious or have decreased consciousness due to decreased brain perfusion. If not treated promptly, acute coronary syndrome and myocardial ischemia may occur. This is due to the decreased perfusion to the heart and stress on the heart in an attempt to compensate for the hypotension.

Finding and addressing the underlying cause of hypotension is the first step in correcting the condition. Some patients may require blood transfusions if blood loss is the cause. Others may need medications, vasopressors, and IV fluid to increase their blood pressure. Patients with acute hypotension should be placed on oxygen to increase tissue perfusion and reduce the risk of multisystem organ failure. Patients may be initially positioned flat, or supine, to reduce the workload of the heart and reduce hypotension; however, this is only a short-term fix and other interventions should also be implemented to address the patient’s blood pressure.


Critically ill patients may lose their ability to self-regulate their temperatures. Core body temperature is generally maintained between 35.5-37.5 degrees Celsius to promote healthy bodily and organ function. Temperatures less than 35 degrees Celsius are considered hypothermic. Hypothermia may develop due to environmental exposure, trauma, sepsis, deep sedation, blood loss, surgery, and cardiovascular events.

In some critical patient conditions, therapeutic hypothermia may be initiated to prevent patients from overheating and reducing their metabolism. Conditions that may warrant therapeutic hypothermia include patients in a coma following cardiac arrest, ischemic stroke, neurogenic fever, and traumatic brain/spinal cord injury. Patients may be cooled with cooled saline bladder irrigations or through machines designed for this purpose. Patients should not be cooled to lower than 33 degrees Celsius and the temperature should be reduced slowly, no faster than 1.5-2 degrees Celsius per hour. When rewarming the patient, temperature should be increased slowly, at 0.5-1 degree Celsius per hour.

Hyperthermia, temperature greater than 38 degrees Celsius, may result due to infection, systemic inflammatory response syndrome, heat stroke, neuroleptic malignant syndrome, and serotonin syndrome. Hyperthermia can become life-threatening if the patient’s temperature exceeds 41.5 degrees Celsius.

Sleep Disruption

Hospitalized patients often experience disrupted sleep patterns. Sleep is essential for healing and normal function. Patients in intensive care units are even more susceptible to sleep disruption due to the nature of their conditions and their environment. Intensive care units are often environments full of disruptive noise, bright lights, sensory overload, and frequent wakings and interventions. Patients may be prescribed and administered medications that alter their sleep function. Their conditions and sleep disruption can cause psychosocial stress that decreases the continuum of future sleep patterns and ability to achieve enough REM sleep. Lack of sleep affects hormone function, immunity, healing, cardiac function, and neurocognitive function.

Symptoms of sleep disruption or deprivation include irritability, depression, frequent yawning, anxiety, lethargy, disorientation, and mood lability. Nurses in critical care should strive to promote healthy sleep patterns. Decreasing nocturnal stimuli, reducing awakenings, promoting a daytime schedule with nighttime relaxation, and reducing cognition-altering medications are all positive interventions for promoting sleep. Pain should be reduced and patients should have their anxiety and depression symptoms addressed with nonpharmacologic methods when possible.

Comfort Concerns

Patients admitted to critical care units are exposed to several stressors that can complicate their hospital stay. Managing these concerns and providing a more comfortable environment, when possible, can improve health outcomes for these patients and improve their overall experience.


One of the most common complications of critical illness is pain. Pain can occur due to illness, as a side effect of therapy, or as an emotional response to a situation. It is an individualized experience and can impact several other bodily systems when not treated appropriately. Pain is often known as the sixth vital sign.

Pain can have systemic effects across the body. In the cardiovascular system, pain may cause increased heart rate and blood pressure. This can stress the heart and worsen cardiovascular disease and cardiac failure. Respiratory manifestations of pain include tachypnea, shortness of breath, increased oxygen needs, decreased tidal volume, and difficulty moving and clearing secretions. Decreased ventilation can increase a patient’s risk for pneumonia and need for supplemental oxygen and supportive ventilation.

Pain can also affect the gastrointestinal system. Most pain medications slow GI motility, which can result in constipation or even ileus or obstruction. Patients may experience mucosal ulcerations due to stress and have symptoms of nausea and vomiting, which increases a patient’s risk for aspiration pneumonia. Patients with GI complications are also at risk for urinary retention due to outlet obstruction and constipation.

Pain can significantly impact the body’s hormone regulation. Catecholamine, cortisol, and glucagon will increase whereas insulin and testosterone decrease in the event of acute pain. The difficulties in hormone regulation can lead to lipolysis and carbohydrate intolerance. Patients may also see changes in their electrolyte balances, as the hormones may cause sodium and fluid retention.

Hematologically, patients in pain may experience increased coagulation and reduced fibrinolysis, placing them at increased risk for bleeding disorders. Leukocytosis and lymphopenia increase the patient’s risk for infection as well.

All patients should have thorough psychological assessments, as pain impacts and often diminishes quality of life. Patients may experience anxiety, depression, anger, poor coping skills, and emotional outbursts due to pain and pain-related complications. Poor sleep quality increases the risk for psychological involvement, and patients should be made as comfortable as possible to encourage healthy sleeping habits.

Palliative Care

Palliative care can be initiated in any patient experiencing serious illness. Palliative care is not the same as hospice care, though, and many palliative care interventions can also be used in hospice care. Palliative care focuses on providing emotional support and managing symptoms in alignment with the goals of the patient and their family. Critically ill patients often sense a loss of control over their environment and their bodies and can greatly benefit from being involved in decision making.

Nursing staff can advocate for their parents to receive palliative care. It does not replace life-saving or treatment-focused interventions. It focuses on communication with the whole healthcare team, including the patients and their families. It can decrease moral distress and provide opportunities for the patient and family to express their concerns and become part of the decision-making process.

Post-Intensive Care Syndrome (PICS)

Many patients admitted to the intensive care unit develop complications that prolong their recovery course. The post-intensive care syndrome (PICS) is the accumulation of health problems that exist related to the patient’s ICU stay. PICS can be composed of both physical deficits and mental deficits. Patients may experience prolonged muscle weakness, cognitive dysfunction, disrupted sleep cycles, and post-traumatic stress disorder.

Mechanical ventilation, sepsis, ICU-related delirium, and prolonged ICU admission (greater than one week) increase a patient’s risk for PICS. Recovery may include external therapy services such as physical therapy, occupational therapy, and counseling/mental health therapy. Patients may struggle to return to normal activity levels up to a year or longer following their illness.

Patients admitted to the ICU are not the only people at risk for PICS. Family members of those admitted to the ICUs may also experience feelings of depression, anxiety, sleep disturbance, and PTSD. To help prevent PICS, nurses should encourage patients and their families to keep a daily wake/sleep schedule, limit overnight stimulation when possible, encourage good nutrition, and take breaks from the ICU setting (for family). Nurses should also proactively advocate for minimizing patient time in sedative or ventilated states, encourage daytime activities/ambulation, and encourage utilization of hospital resources such as social work, clergy, and case managers.

End of Life

Nurses will likely be responsible for end of life care at some point in their career. End of life care is multidimensional and individualized to each patient. Patients should be included in the end of life discussions when possible. If patients are unable to participate, active participation by the patient’s family should be sought.

Supportive care and symptom management are the nursing priorities during this transition. Many patients and their families will have times of pain and suffering. Being supportive in the environment and using prescribed PRN pain medications would be indicated. Patients near death may experience symptoms of pain, dyspnea, anxiety, hypoxemia, agitation, anorexia, nausea, vomiting, depression, and withdrawal.

Providing families and patients with anticipatory guidance and gathering resources to provide emotional and spiritual support helps patients transition through this time more easily. Time should be spent setting goals for the family to help develop plans for each stage of end of life. Nurses must also advocate for their patients to ensure their needs are being met.


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