General Approach to the Critically Ill Patient

Published on 07/03/2015 by admin

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Chapter 1 General Approach to the Critically Ill Patient

Manuel Pardo, Jr. , MD, Michael A. Gropper, MD, PhD

This book deals with many different aspects of critical care. Each disorder has specific diagnostic and management issues. However, when initially evaluating a patient, one must have a conceptual framework for the patterns of organ system dysfunction that are common to many types of critical illness. Furthermore, in the patient with multiple organ failure, resuscitation or stabilization is often more important than establishing an immediate, specific diagnosis.

1 Which organ systems are most commonly dysfunctional in critically ill patients?

The respiratory system, the cardiovascular system, the internal or metabolic environment, the central nervous system (CNS), and the gastrointestinal tract.

2 What system should be evaluated first?

The first few minutes of evaluation should address life-threatening physiologic abnormalities, usually involving the airway, the respiratory system, and the cardiovascular system. The evaluation should then expand to include all organ systems.

3 Which should be performed first—diagnostic maneuvers or therapeutic maneuvers?

The management of a critically ill patient differs from the typical sequence of history and physical examination followed by diagnostic tests and therapeutic plans. The pace of assessment and therapy is quicker, and simultaneous evaluation and treatment are necessary to prevent further physiologic deterioration. For example, if a patient has a tension pneumothorax, the immediate placement of a chest tube may be lifesaving. Extra time should not be taken to transport the patient to a monitored setting. If there are no obvious life-threatening abnormalities, it may be appropriate to transfer the patient to the intensive care unit (ICU) for further evaluation. Many patients are admitted to the ICU solely for continuous electrocardiogram monitoring and more frequent nursing care.

4 How do you evaluate the respiratory system?

The most important function of the lungs is to facilitate oxygenation and ventilation. Physical examination may reveal evidence of airway obstruction or respiratory failure. These signs include cyanosis, tachypnea, apnea, accessory muscle use, gasping respirations, and paradoxic respirations. Auscultation may reveal rales, rhonchi, wheezing, or asymmetric breath sounds.

5 Define paradoxic respirations and accessory muscle use. What is their significance?

Normal breathing involves simultaneous rise and fall of the abdomen and chest wall.

image A patient with paradoxic respirations has asynchrony of abdominal and chest wall movement. With inspiration, the chest wall rises as the abdomen falls. The opposite occurs with exhalation.

image Accessory muscle use refers to the contraction of the sternocleidomastoid and scalene muscles with inspiration. These patients have increased work of breathing, which is the amount of energy the body consumes for the work of the respiratory muscles. Most patients use accessory muscles before they have development of paradoxic respirations. Without support from a mechanical ventilator, patients with paradoxic respirations or increased work of breathing will eventually have respiratory muscle fatigue, hypoxemia, and hypoventilation.

6 What supplemental tests are useful in evaluating the respiratory system?

Although all tests should be individualized to the particular clinical situation, arterial blood gas (ABG) analysis, pulse oximetry, and chest radiography rapidly provide useful information at a relatively low cost-benefit ratio.

7 What therapy should be considered immediately in a patient with obvious respiratory failure?

Mechanical ventilation may be an immediate life-sustaining therapy in a patient with obvious or impending respiratory failure. Mechanical ventilation can be carried out invasively or noninvasively. Invasive ventilation is carried out via endotracheal intubation or tracheotomy. Noninvasive ventilation is instituted with a nasal mask or a full face mask. Even if the patient does not have obvious respiratory distress, supplemental oxygen should be administered until the oxygen saturation is measured. The risk of development of oxygen-induced hypercarbia is rare in any patient, including those with an acute exacerbation of chronic obstructive pulmonary disease.

8 How do you evaluate the cardiovascular system?

The most important function of the cardiovascular system is the delivery of oxygen to the body’s vital organs. The determinants of oxygen delivery are cardiac output and arterial blood oxygen content. The blood oxygen content, in turn, is determined primarily by the hemoglobin concentration and the oxygen saturation. It is difficult to determine the hemoglobin concentration and the oxygen saturation by physical examination alone. Therefore the initial evaluation of the cardiovascular system focuses on evidence of vital organ perfusion. New technology may allow rapid assessment of hemoglobin with use of a noninvasive spectrophotometric sensor.

9 How is vital organ perfusion assessed?

The measurement of heart rate and blood pressure is the first step. If the systolic blood pressure is below 80 mm Hg or the mean blood pressure is below 50 mm Hg, the chances of inadequate vital organ perfusion are greater. However, because blood pressure is determined by cardiac output and peripheral vascular resistance, it is not possible to estimate cardiac output from blood pressure alone. The vital organs and their method of initial evaluation are as follows:

image Lungs (see Questions 4–7)

image Skin: Assess warmth and capillary refill in all extremities.

image CNS: Assess level of consciousness and orientation.

image Heart: Measure blood pressure and heart rate, and ask for symptoms of myocardial ischemia (e.g., chest pain).

image Kidneys: Measure urine output and creatinine level.

10 What supplemental tests are useful in the initial evaluation of the cardiovascular system?

Electrocardiography is a potentially useful diagnostic test with a low cost-benefit ratio. Cardiac enzyme tests, such as troponin measurement, are generally available within hours and can suggest myocardial injury. Other tests, which may entail more risk and cost, should be determined after the initial evaluation. These may include echocardiography, right-sided heart catheterization, central venous pressure measurement, or coronary angiography.

11 What therapies should be considered immediately in a patient with hypotension and evidence of inadequate vital organ function?

Fluid and vasopressor therapy can rapidly restore vital organ perfusion, depending on the cause of the deterioration. In most patients, a fluid challenge is well tolerated, although it is possible to precipitate heart failure and pulmonary edema in a volume-overloaded patient. Other therapies that may be immediately lifesaving include thrombolysis or coronary angioplasty for an acute myocardial infarction. Patients with hypotension from sepsis may benefit from early therapy involving defined goals for blood pressure, central venous pressure, central venous oxygen saturation, and hematocrit.

12 How do you evaluate the metabolic environment?

The clinical laboratory is required for most metabolic tests. It is difficult to evaluate the metabolic environment by physical examination alone.

13 Why are metabolic changes important to detect in a critically ill patient?

Metabolic abnormalities such as acid-base, fluid, and electrolyte disturbances are common in critical illness. These disorders may compound the underlying illness and require specific treatment themselves. They may also reflect the severity of the underlying disease. Metabolic disorders such as hyperkalemia and hypoglycemia can be life threatening. Prompt testing and treatment may reduce morbidity and improve patient outcome.

14 Which laboratory tests should be performed in the initial evaluation of the metabolic environment?

The selected tests should have a rapid reporting time, be widely available, and be likely to produce a change in management. Tests that fit these criteria include measurements of glucose, white blood cell count, hemoglobin, hematocrit, electrolytes, anion gap, blood urea nitrogen, creatinine, and pH. Elevated lactate levels suggest tissue hypoperfusion, and normal lactate clearance is suggestive of adequate fluid resuscitation. Some of these tests may be unnecessary in a particular patient, and supplemental testing may be useful in others.

15 How do you evaluate the CNS?

A neurologic examination is the first step in evaluating the CNS. The examination should include assessment of mental status (i.e., level of consciousness, orientation, attention, and higher cortical function). CNS disturbances in critical illness can be subtle. Common changes include fluctuations in mental status, changes in the sleep-wake cycle, or abnormal behavior. The remainder of the neurologic examination includes assessment of respiratory pattern, cranial nerves, sensation, motor function, and reflexes. Delirium, which is common in ICU patients, can be evaluated with the confusion assessment method (CAM-ICU).

16 What diagnostic tests and therapies should be immediately considered in a patient with altered mental status?

Oxygen therapy may be useful in patients with altered mental status from hypoxemia. Pulse oximetry or ABG analysis should be done to evaluate this. Intravenous dextrose may be lifesaving in patients with hypoglycemia. Additional diagnostic tests may be indicated depending on the clinical situation. Lumbar puncture, head computed tomographic (CT) or magnetic resonance imaging scan, electroencephalography, and metabolic testing may be useful in directing specific therapies. Patients with acute ischemic stroke may benefit from tissue plasminogen activator therapy, which is most effective when administered within 90 minutes of symptom onset.

17 How do you evaluate the gastrointestinal tract?

History and abdominal and rectal examination are the first steps in an initial evaluation of the gastrointestinal tract. Abdominal catastrophes such as bowel obstruction and bowel perforation are common inciting events leading to multiple organ failure. In addition, abdominal distention can reduce the compliance of the respiratory system, leading to progressive atelectasis and hypoxemia. Further diagnostic tests such as chest radiography, abdominal ultrasonography, plain radiography of the abdomen, or abdominal CT scan may be useful in certain patients. For example, the finding of free air in the abdomen may lead to surgery for correction of bowel perforation.

18 Besides the information about current organ system function, what else should one learn about a patient in the initial evaluation?

After assessing current medical status, one should develop a sense for the physiologic reserve of the patient, as well as the potential for further deterioration. This information may often be gained by observing the patient’s response to initial therapeutic maneuvers. It is also important to realize that patients may not desire cardiopulmonary resuscitation or other life-support therapies. If the patient has completed an advance directive, such as a durable power of attorney for health care, these guidelines should be followed or discussed further with the patient.

19 What measures can be taken to reduce patient morbidity in the ICU?

The prevention of complications in the ICU is an important patient safety issue. Each ICU should develop strategies to prevent complications such as venous thromboembolism, nosocomial pneumonia, and central line infections. In the last several years, a number of clinical trials have focused on reducing morbidity and mortality among critically ill patients. Many of these studies have evaluated common ICU problems such as acute respiratory distress syndrome, sepsis, and postoperative hyperglycemia. Practices such as hand washing can have a major impact on the incidence of complications.

Key Points General Approach to Critically Ill Patientsimage

1. In the first few minutes, try to identify any life-threatening problems that require immediate treatment.

2. In patients with respiratory distress, consider whether immediate mechanical ventilation is necessary to prevent respiratory arrest.

3. Administer a fluid challenge for hypotensive patients without evidence of pulmonary edema.

4. When possible, use treatment strategies that have demonstrated benefit in clinical trials of critically ill patients.

Bibliography

1 Dellinger R.P., Levy M.M., Carlet J.M., et al. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008. Crit Care Med. 2008;36:296–327.

2 Ely E.W., Margolin R., Francis J., et al. Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Crit Care Med. 2001;29:1370–1379.

3 Fonarow G.C., Smith E.E., Saver J.L., et al. Timeliness of tissue-type plasminogen activator therapy in acute ischemic stroke: patient characteristics, hospital factors, and outcomes associated with door-to-needle times within 60 minutes. Circulation. 2011;123:750–758.

4 Luce J.M. End-of-life decision making in the intensive care unit. Am J Respir Crit Care Med. 2010;182:6–11.

5 Miller R.D., Ward T.A., Shiboski S.C., et al. A comparison of three methods of hemoglobin monitoring in patients undergoing spine surgery. Anesth Analg. 2011;112:858–863.

6 Pronovost P., Needham D., Berenholtz S., et al. An intervention to decrease catheter-related bloodstream infections in the ICU. N Engl J Med. 2006;355:2725–2732.

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