4 RN CEs

 

Author: Kristi Hudson RN MSN CCRN

Written: January 22, 2005

Updated: September 11, 2009

 

Course Objectives

Upon completion of this course the student will be able to:

• List 2 special considerations when intubating a trauma patient
• Differentiate between mechanical ventilation modes SIMV and AC
• Describe 2 nursing assessments/interventions for the intubated patient
• Discuss when physician notification is necessary for intubated patients
• State 2 benefits of End Tidal CO2 monitoring
• Give 1 troubleshooting tip for an End Tidal CO2 waveform that is reading zero
• Explain the difference between resp/metabolic acidosis
• Explain the difference between resp/metabolic alkalosis
• Describe the role of the kidneys in maintaining acid-base balance
• Describe the role of the lungs in maintaining acid-base balance

Airway Management and Intubation Consideration for the Trauma Pt.

Virtually all algorithms begin with attention to and protection of the airway. In a patient with a traumatic injury, airway management assumes an essential role to stabilization and survival of the patient. Also with the trauma patient, careful assessment and care must be given to the potential for cervical injury or instability prior to any attempt at intubation. Immobilization of the cervical spine must be instituted until a complete clinical and radiological evaluation has excluded injury.

Laryngeal Injury

• The larynx may be fractured by contact with the steering wheel. The airway is at risk, as bleeding into the larynx, hematoma, or swelling may occur.
• Clinical Findings: the "Adam's apple" area may be puffy, distorted, or subcutaneous air may be palpable in the neck (but not in the chest).
• Diagnosis: the clinical findings are usually sufficient to diagnose laryngeal injury.
• Treatment: intubation should be performed on any patient suspected to have laryngeal injury. If the injury is isolated, and judged to be not severe, the patient may be observed unless signs of airway encroachment develop.

Airway Burn

• Airway burns are most likely to occur in enclosed-space burn injuries. They are not as likely (but must be screened for) in "flare-up" burns, such as when gasoline in a carburetor flares into the face. Once swelling begins, it may progress so rapidly that intubation becomes extremely difficult.
• Clinical Findings: assume the airway is burned if there are burns around the mouth, nose, neck, and chest or if the victim had significant time in an enclosed-space fire or explosion. Singed nasal hairs, red tender oral membranes or obvious intra-oral or pharyngeal burns indicate likely airway burn.
• Diagnosis: based on history and clinical examination.
• Treatment: if airway burn is suspected, intubate the patient.

Severe Facial Fractures

• Severe facial trauma often results in unstable tissues, which can occlude the airway. While lifting the jaw and inserting an oral or nasal airway may help temporarily, the airway will continue to be at risk due to bleeding, swelling, and hematoma formation. Patients with severe facial fractures will usually have a decreased level of consciousness due to intracranial injury. Neck fracture is also common in these patients.
• Clinical Findings: facial fractures sufficient to put the airway at risk will almost always be unstable. Bilateral eyelid swelling and a sunken facial appearance suggest a cranio-facial fracture.
• Diagnosis: the diagnosis of risk to the airway is made based on the finding of significant fracturing and soft tissue injury. The airway is the critical issue - the nature of the fracturing can be determined at leisure once the airway is safe. Treatment: if trauma involves both the mandible and upper face, and the C-spine is still at risk, you are probably better off performing cricothyrotomy. If the C-spine is OK, oral intubation may be attempted first. Nasal intubation should be avoided at all costs as it may cause complications such as entry into open fractures, and may restart bleeding into the airway.

Cervical Spine Injury

• The cervical spine is considered injured in all trauma victims until proven otherwise. In the multiply injured or intoxicated patient, absence of pain or tenderness does NOT exclude cervical fracture.
• Clinical Findings: the presence of a step-off deformity may indicate a fracture or dislocation. Complete spinal cord injury will result in a flaccid areflexia, flaccid sphincters, and diaphragmatic breathing. The patient may be able to flex, but not extend the arms. Painful stimulation may be felt only above the clavicle. Neurogenic shock results from loss of sympathetic nerve stimulation of the blood vessels and heart. Typically, both pulse rate and systolic pressure are around 80, with warm, pink extremities. Hypotension in the injured patient should first be assumed due to hemorrhage. Only after fluid challenge, ruling out intra-peritoneal hemorrhage, and measuring a normal CVP and normal urine output, should the hypotension be blamed on spinal cord injury.
• Diagnosis: by cross-table cervical spine x-ray.
• Treatment: intubate with full cervical spine precautions.

Modes of Mechanical Ventilation

Volume Ventilation - The main advantage of volume-controlled ventilators is guaranteed minute ventilation. This is particularly important in the operating room, where lung compliance may be influenced by the type of surgery involved, (abdominal or chest surgery), and in the ICU or in transit if patient’s tidal volumes are not being continuously monitored.

SIMV (Synchronized Intermittent Mandatory Ventilation) -SIMV may be full or partial support. SIMV allows the patient to breathe spontaneously between mandatory machine breaths. These extra breaths will deliver a spontaneous tidal volume. The patient controls the inspiratory time and the size of the spontaneous tidal volumes depending on patient effort and muscle strength, lung compliance, airway resistance and whether or not Pressure Support is present to "boost" spontaneous tidal volume delivery. When the set rate is high enough, the patient may "ride" the ventilator and not make significant spontaneous efforts. Machine breath waveforms will be no different than when the patient is in Assist Control. Machine breaths in both Assist Control and SIMV are identical. As the set machine rate is lowered or weaned and no longer able to keep the PaCO2 in the normal range by itself, the patient will usually begin breathing spontaneously to supplement the fewer machine breaths. 

AC (Assist Control Ventilation) - In volume assist-control (often labeled “volume control”) patients may receive either controlled or assisted breaths. When the patient triggers the ventilator, he/she receives a breath of identical duration and magnitude as the mandatory breath. The patient receives a breath of this type irrespective of actual minute ventilation requirement. The “interactive” element of this mode is merely that the patient receives a breath when they want one, nothing else. The advantage of this mode is that patients can breathe spontaneously without working. The patient is fully rested on the ventilator, except for triggering, assuming that the peak flow is adequate.

Pressure Ventilation Mode - Provides pressure that is constant, which causes tidal volume to vary with changes in compliance and airway resistance.

PCV (Pressure Controlled Ventilation), refers to the type of breath delivered, not the mode of ventilation. Many different modes are pressure controlled. Conventionally, the term “pressure control” refers to an assist control mode (there is also a SIMV pressure control mode on some ventilators). In pressure control, a pressure-limited breath is delivered at a set rate. The tidal volume is determined by the preset pressure limit. This is a peak pressure rather than a plateau pressure limit (easier to measure). The operator also sets the inspiratory time. Again this is a trade off between short times with rapid inflow and outflow of gas, and long times with gas trapping.

In a nut shell: S IMV- set breaths are at a specific tidal volume, patient is on their own for all spontaneous breaths. AC-All breaths whether set or spontaneous give the same preset tidal volume. PCV-Pressure not volume is set, when the lungs reach the preset pressure, that’s it, the tidal volume is what it is…..

Nursing Management of the Mechanically Ventilated Patient

Assessment:

Verify position of ETT in reference to lip / teeth with securing device change and position changes  

• Assess skin condition around ETT / oral mucosa
• Verify ventilator settings q shift and with order changes.
• Monitor patient for tolerance of ventilator support (LOOK AT YOUR PATIENT)
• Assess and Document:
• Breath Sounds
• Respiratory Rate and Pattern
• SpO2
• Peak Inspiratory Pressure
• Exhaled Tidal Volume / Minute Volume
• Amount / Consistency of Secretions
• Response to Suctioning / Ventilator Changes / Activity
• Anxiety
• Rest/Activity Balance

Interventions:

• Sedation should be considered to optimize patient comfort.
• Provide a means for patient to communicate (pen / paper, letter board, etc.)
• Keep patient and family informed of progress, plan of care, and anticipated outcomes. (Make sure family is aware or has seen their loved one suctioned)
• An oral airway may be used if patient bites or gums ETT. It should be removed and oral mucosa assessed q 24 hours.

Notify MD for:

• SpO2 < 90% or Change Greater Than 5%
• Unplanned Extubation
• Respiratory Distress
• Inadequate Sedation
• Increased Peak Airway Pressure (Especially with Pressure Control Mode)

End Tidal CO2 Monitoring

ETCO2 is the partial pressure or maximal concentration of carbon dioxide (CO2) at the end of an exhaled breath, which is expressed as a percentage of CO2 or mmHg. The normal values are 5% to 6% CO2, which is equivalent to 35-45 mmHg. CO2 reflects cardiac output (CO) and pulmonary blood flow as the gas is transported by the venous system to the right side of the heart and then pumped to the lungs by the right ventricles. When CO2 diffuses out of the lungs into the exhaled air, a device called a capnometer measures the partial pressure or maximal concentration of CO2 at the end of exhalation.

How do ETCO2 monitors work?

A light is shone through the expired air and the degree of absorption of a certain frequency of infrared light is proportional to the concentration of CO2. The light may be split with half passing through a reference cell. The light may also be 'chopped' so that it is not continuously heating the gas in the reference cell. The plateau is essential for accurate analysis. The ETCO2 device is connected in line to the ventilator circuit.

Benefits of End Tidal CO2 Monitoring

Because increased metabolic rates cause and increased CO2, there is great benefit to continually monitoring End Tidal CO2. An increasing End Tidal CO2 can assist with the early warning and diagnosis of such dangerous hypermetabolic conditions as malignant hyperthermia, thyrotoxic crisis, and severe sepsis.

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