Introduction

Caring for a patient with traumatic injuries means recognizing and discerning different signs and symptoms at once, which is why these patients are often kept in the Intensive Care Unit (ICU) or other higher levels of care. A patient may initially be considered stable enough for a medical, surgical, or telemetry floor but then needs to be transferred to a higher level of care due to a worsening condition.  

One sign of a deteriorating condition is impaired tissue perfusion. Impaired tissue perfusion can have a wide range of negative effects, including organ dysfunction, loss of limb, and even death (4). All nurses must be aware of the signs of impaired tissue perfusion so they can act quickly to support their patients as required. 

Causes of Impaired Tissue Perfusion 

Any condition that limits blood flow can cause reduced perfusion to vital organs and distal extremities. This reduced blood flow can result in tissue death, leading to organ damage, loss of limb, or even patient death. The complicated injuries and complex mechanisms of compensation and coagulation in a trauma patient mean that the nurse needs to be aware of the various causes of impaired tissue perfusion.  

Impaired tissue perfusion may be caused by hypovolemia. Hypovolemia can be caused by poor intake or, in the case of trauma, by internal or external bleeding. Hypovolemia presents as hypotension, especially orthostatic hypotension, and a high hematocrit (4). Signs of internal bleeding include unexplained hypotension, decreased hemoglobin, pain, and firmness at the site of bleeding (6). Internal bleeding inside an enclosed space, such as a limb, can result in compartment syndrome. Compartment syndrome is when pressure inside a closed compartment increases to the point that nerves and blood vessels are compressed, resulting in ischemia and nerve injury (5). 

Conditions that lead to decreased cardiac output, such as cardiac shock, cardiac arrest, and myocardial infarction (MI), also cause decreased perfusion. The decreased cardiac output from these conditions inhibits the delivery of oxygen-rich blood to tissues despite an adequate blood volume. Impaired blood flow because of a physical blockage, either internal (such as a thrombus) or external (too tight of a cast), can cause impaired tissue perfusion. Medications used in critical care, vasopressors or “pressers,” can decrease distal perfusion to the point of tissue death, a known risk.  

Brain Perfusion  

Impaired brain perfusion may be caused by intracranial swelling, intracranial hemorrhage, physical blockage (thrombus or embolus), hypovolemia, or low cardiac output.  

The brain consumes typically about 20% of a person’s cardiac output, making it very susceptible to impaired perfusion (1). A patient’s level of consciousness is a strong indicator of brain perfusion (1). Assessing and documenting the patient’s consciousness level and any changes is essential in a trauma patient. Commonly used and validated tools to evaluate cognition and level of consciousness include the Glasgow Coma Scale (GCS), Mini-Mental Status Examination (MMSE), and the Montreal Cognitive Assessment (MoCA) (1).  

Before noticeable changes, such as changes in the level of consciousness, subtle changes may be observed by asking the patient orientation questions. Ask the patient concrete questions and be consistent (1). Use the documentation tool provided by your facility to note alertness, responsiveness, and orientation.  

Orientation questions may include the current season, month, president, etc. Be careful not to ask too difficult questions, as this may frustrate patients. For example, questions about the day of the week or the specific date may be frustrating and often confusing, even for those of us without brain trauma!  

Note that pain medication, sedation, and fatigue can affect the level of consciousness (LOC). Traumatic brain injuries may result in fluctuations in LOC depending on fatigue. Documenting changes in LOC and reporting trends to the provider and the next shift is essential. Significant changes in orientation or decreases in LOC should be reported to the provider immediately, as it may indicate impaired brain tissue perfusion.  

Renal Perfusion  

The kidneys can be our best friends when we are assessing a patient for perfusion issues. Similar to the brain, the kidneys receive 20-25% of cardiac output making them one of the most sensitive organs to poor perfusion (7). Impaired renal perfusion may be caused by hypovolemia, low cardiac output, or physical blockage (swelling, thrombus, etc.).  

The initial sign of impaired renal perfusion is low urinary output. Urinary output may be difficult to assess due to collection or documentation errors, so rising serum creatinine is another key indication of impaired renal function (2). It is easier to note accurate urinary output when the patient has an indwelling catheter, but it is also possible and important to measure output with patients using a bedpan, bedside commode, or bathroom toilet.  

External catheter devices have gained popularity as an alternative to the indwelling catheter in an attempt to reduce the risk of urinary tract infections. Remember that once trauma patients are transferred to a lower level of care, they can still develop worsening conditions, and monitoring and documenting intake and output is essential for all nurses. Note that the acceptable minimum level of urine output can be considered either 30mL/hour as a general rule, or 0.5 to 1.5 mL/kg/hour for more accuracy (especially in pediatric patients) (3).  

Because urinary output is essential to monitor and document, the nurse may need to advocate for an indwelling catheter for the patient with decreasing output, especially if the patient has become incontinent as their condition worsens. Keep in mind the risk for urinary tract infections and discuss the risk versus need with the provider.  

In addition to low urine output, poor renal perfusion can cause an increase in blood urea nitrogen (BUN) or creatinine (7). These labs can help confirm suspected poor renal function. As a reminder, the normal range for BUN is 6-24mg/dL, and normal creatinine is 0.6-1.3mg/dL (7). When the kidneys are not well perfused, they filter out less of these compounds, and therefore the serum levels will rise. 

Capillary Refill: Impaired Tissue Perfusion Assessment

Consider capillary refill time a standard part of the nursing assessment for trauma patients and post-surgical patients with limb injuries. Distal perfusion may be impaired because of hypovolemia, decreased cardiac output, blockage (thrombus or embolus), significant swelling (as seen in compartment syndrome), or medications (vasopressors). Any of these events may occur in a patient with traumatic injuries. Assess capillary refill by pinching the finger or toe at the nailbed for 5 seconds and then observing the time it takes for the blood flow and color to return to the tissue.

Normal capillary refill time in adults should be less than 3 seconds (4). Documenting and reporting capillary refill times over 3 seconds may indicate decreasing peripheral perfusion and worsening conditions. Capillary refill time is both an early indicator of deteriorating condition and a reliable measure of improvement (4). Remember that faster doesn’t always mean better with capillary refill times. A brisk cap refill may indicate acute compartment syndrome because the blood cannot exit the tissues due to swelling and impaired circulation in the extremities (5).

Checking capillary refill time in multiple locations can give you insight into total body perfusion versus perfusion to a specific area. This can help distinguish between hypovolemia—which affects the entire body—and a localized process, such as compartment syndrome or thrombus.

Distal Pulses: Impaired Tissue Perfusion Assessment

Limb trauma may result in decreased distal perfusion because of swelling or impaired circulation, but it may also indicate hypovolemia or decreased cardiac output. In an emergency, pulses closer to the heart, such as the carotid, are used to assess for a pulse. Remember this from basic life support training: we check the carotid for a pulse before starting CPR.

Assessing and documenting distal pulses and monitoring trends or changes are essential in assessing distal perfusion. Assess the radial and pedal artery pulses as a regular part of the physical assessment. Assess pulses distal to the site of injury for limb injury or vascular injury that affects that limb. It may be necessary to mark the area where the pulse is found to perform consistent assessments, especially for pedal pulses. A Doppler may be necessary to confirm circulation to the area if the pulse is not palpable.

A patient may have a splint, cast, or another device to support the limb. If the pulse is not palpable because of a device in the way, be sure to assess and document the capillary refill frequently and note any signs/symptoms of compartment syndrome. For example, a patient with a splint from the right axilla to the mid-palm may need frequent assessments of the fingers since the splint blocks the radial pulse.

Placing a pulse oximeter on a digit of the affected limb is another way of assessing peripheral perfusion. Plethysmography (what we call the “pleth”) is directly related to blood flow to the digit being monitored (7). If blood flow to the digit decreases, so will the pleth waveform.

Case Study

EMS brings in a 23-year-old male following a motor vehicle accident. He has an open femur fracture to the right leg, four broken ribs on the left, a head laceration over the left eye, and reports severe abdominal pain. The head CT is negative for acute trauma. The abdominal CT shows a liver laceration.

Case Study Continued

The patient is stabilized and transferred to the ICU overnight for monitoring and to prepare for surgical fixation of the femur the next day. The night shift nurse notes a slight decrease in the right posterior tibial and pedal pulses and increased cap refill time. Vitals are stable, and the left leg remains within normal limits.

Case Study Continued

The patient is taken to the OR for an emergency fasciotomy to release the pressure in the compartment surrounding the femur fracture. After the procedure, he is returned to the ICU, where he struggles to maintain his oxygen saturation, and a chest x-ray reveals that he has developed a hemothorax. He has a chest tube placed, and 350 mL of blood drains into the collection device. While the provider reviews the labs and plans the following interventions, the nurse notices no output in the patient’s urinary catheter.

Case Study Continued

The nurse reports the lack of urine output to the provider and that they suspect poor renal perfusion.

The patient is stabilized and, several days later, transferred to the medical/surgical floor. The experienced nurse advises rotating the site for the oxygen saturation probe to the right second toe.

When physical therapy attempts to mobilize the patient, he becomes dizzy and lightheaded and feels like he is going to “pass out.” The nurse helps the physical therapist return the patient to bed. When lowering the head of the bed, they recognize that the patient experienced orthostatic hypotension.

The patient has continued to improve and is now adequately recovered for discharge.

Conclusion

While trauma patients may not be your specialty, traumatic injuries can result from a fall, motor vehicle accident, or emergency procedure. If you are asked to float to a trauma unit, you may find yourself caring for a trauma patient who is believed to be stable when, in fact, they are not. Changes in the patient’s condition may be subtle but indicate a serious problem. Knowing the signs of impaired tissue perfusion can help you address circulatory emergencies faster and potentially save your patient’s life or limb! Many of these concepts related to perfusion can also be applied to situations outside of trauma. Make these assessments a part of your routine so you can be the nurse who notices something is wrong sooner rather than later.