Surgical Critical Care

Indications for Intubation

 

Respiratory Failure: Inability to oxygenate or eliminate CO2

Inability to neurologically protect airway

Loss of airway secondary to anatomy (injury and / or edema)

 

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AOV

           

A = Airway

1. Is the patient’s airway patent? 

2. Can the patient protect their airway from a neurologic standpoint?

 

O = Oxygenate

1. Can they generate spontaneous breaths?

2. Are they strong enough to maintain a respiratory rate and tidal volume to support Oxygenation?

 

V = Ventilation

1. Is the ventilation / perfusion ratio balanced? Are oxygenation and CO2 clearance occurring without excessive work of breathing?

 

 

 

 

Once a patient is safely intubated or has a secure surgical airway: The ventilator settings are chosen based on the reason for intubation. These reasons are respiratory failure, inability to protect airway for neurologic reasons or mechanical airway obstruction.

 

1. Respiratory Failure

   1. Usually this will require full positive pressure support with ventilator programmed breaths. The pattern in which breaths are delivered is referred to as the ‘mode’ of ventilation.  A mode is chosen to minimize ventilator dysynchrony and optimize ventilation. The respiratory rate, tidal volume, Positive end expiratory pressure (PEEP) and Pressure Support (PS) are settings on the ventilator which aim to optimize lung recruitment and ventilation / perfusion matching (V/Q).

 

 

1. Standard Modes:

   1. Assist Control Ventilation – Ventilator programmed breaths and patient requested breaths are delivered in the same way by the ventilator.

   2. Intermittent Mandatory Ventilation – Only ventilator programmed breaths are fully supported by the ventilator. Patient requested breaths (per minute) are only supported by the degree of pressure support ordered by the care team.

   3. Pressure Support Ventilation - Only used in patients who initiate an adequate minute ventilation (tidal volume / respiratory rate) to maintain CO2 clearance and oxygenation. No ventilator programmed breaths occur in PS mode. The degree of assistance is determined by the amount of pressure support ordered by the care team.

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1. Advanced modes: When a patient has severe respiratory dysfunction, alternate modes are available such as Airway Pressure Release Ventilation (APRV) and Pressure Regulated Volume Control (PRVC). In these instances the ICU Attending should be primarily involved  in all ventilator management decisions.  Additionally, the comfort level of the covering respiratory therapist and bedside nurses should influence the decision to use these advanced modes.

 

1. Inability to protect airway (neurologic)

If a patient can generate their own breaths, the most they may need is a pressure support mode. However, patients with severe traumatic brain injury may need to be placed on mandatory ventilator mode for tight control of CO2 levels. Hypercarbia can increase ICP by vasodilating cerebral vasculature. Neurologic prognosis dictates the need for long-term airway protection (i.e. tracheostomy appliance). Prognostic discussions with neurosurgery and / or neurology should happen early in a patient’s hospital course when they have severe neurologic compromise from trauma or shock.

 

1. Loss of airway anatomy

   1. Often patients intubated for purely mechanical airway protection are able to generate their own spontaneous breaths (e.g. edema, airway injury, mediastinal infections or masses.)  If a patient can generate their own breaths, the most they may need is a pressure support mode. The choice to add mandatory ventilator breaths should be based on work of breathing or clinically relevant V/Q mismatch. Prognosis for regaining patent airway anatomy determines necessity and timing of tracheostomy

 

 

Highland Hospital: Adult Respiratory Ventilator Protocol

 

I. Adult Invasive Ventilation Protocol Initial Parameters and Goals

A. Volume-Ventilation may be used for the majority of patients, but pressure- ventilation (PV or PRVC) should be considered if peak pressures rise over 40 cm H2O or plateau pressures rise >30 cm H2O.

B. Tidal Volume: 6 to 8 cc/Kg of ideal body weight (IBW), while maintaining plateau pressure < 30 cm H2O and delta P < 20 cm H2O.

C. FiO2: Initial setting of 0.6 to 0.9 until results from arterial blood gases (ABG) can be obtained and the setting adjusted.

1. Initial ABG should be obtained 15-45 minutes from start of ventilation 


2. Pulse oximetry should be correlated with initial ABG and the patient and subsequently monitored with continuous pulse oximetry to maintain SpO2 at or above patient’s normal or >90% SpO2 (Oxygen saturation by pulse oximetry).

3.  PEEP 5 to 15 cm H2O. Set initial PEEP at 5 cm H2O, unless otherwise indicated. Higher PEEPs may be required with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS).

D. Pressure Support (PS): 5 to 20 cm H2O. Maintain Pplateau <30 cm H2O and delta P < 20 cm H2O. PS should be adjusted to reduce work of breathing and patient fatigue and support effective ventilation.

G. Begin with I:E ration of 1:3   The I:E ratio should be optimized along with total cycle time (TCT) to provide optimum mean airway pressure, lung filling, lung emptying (minimizing air-trapping/Auto-PEEP), patient/ventilator synchrony.

 

II. Ventilator Adjustments Based on Patient Assessment

1. Initial assessment will be performed within 15-45 minutes from start of ventilation. 


2. Assessment will include evaluation of the patient’s general appearance, blood pressure, heart rate, breath sounds, ventilating pressures and volumes and arterial blood gases (ABG).

3. C. Ventilator synchrony

“Dysynchrony” (aka ‘fighting the ventilator’) is a phenomenon that occurs when the inspiratory breath is resisted by the patient. Dysynchrony with the ventilator can be affected by several factors:

1. Anxiety

2. Pain

3. Chest wall rigidity

4. Positioning

Although a cornerstone of ventilator synchronization depends on adequate sedation and analgesia, ventilator mode adjustment can optimize patient comfort while on positive pressure ventilation.

Spontaneous Breathing Trial    

 

Assess patient for SAT (Spontaneous Awakening Trial)

Exclusion Criteria

Fresh (72 hours) open abdomen

Active seizures

Escalating doses of sedation for ongoing agitation

Neuromuscular blockade

Hemodynamically unstable

Evidence of increased ICP/ Moderate-Severe Head Injury

Critical airway ( as indicated by MD)

Major Chest Injury (i.e. flail chest)

No significant arrythmias

 

 

     

                                                                                                                       

 

 

Eligible

Yes                                                                No

                                                                                                          

 

Perform SAT (Spontaneous Awakening Trial)

Place OG/NG to suction

Hold enteral feedings and make appropriate changes to Insulin if patient is receiving Insulin

Allow analgesia for active pain

For those on benzodiazepine drips >7 days, decrease sedatives by 50% and assess patient need for soft wrist restraints to avoid self extubation

If after 1 hour the patient is not awake discontinue sedatives

 

 

Assess for SAT the following morning

 

                                                                       

 

 

 

 

 

 

 

                                               

 

 

 

 

Monitor for up to 4 hours or until the following:

 

 

Failed:   

Sustained anxiety

Agitation/delerium

Uncontrolled Pain

Respiratory rate >35 for 5 min

SP02 < 88% for 2 min

Acute cardiac dysrhythmia

Hemodynamic instability

 

 

Restart sedatives at ½ the previous dose and titrate to comfort. Consider adjunctive narcotics or antipsychotics.

Passed:  

Opens eyes to verbal stimuli

Follows simple commands

No evidence of agitation observed                       

   

 

 

 

 

 

 

 

 

 

     Proceed to Weaning Pathway

  

 

 

 

Ventilator Weaning

Daily spontaneous breathing trials: All intubated patients who are not in critical condition, should be considered for a daily spontaneous breathing trial. If:

< >SpO2 > 90%PEEP < 8 cm H20FiO2 < 50%Minute Ventilation < 12 L/minHemodynamically stableHR > 50 and < 120 bpmSBP > 90 and < 180 mm HgPatient initiates spontaneous inspiratory effortsPatient is able to any of the follow simple commandsOpens eyes, Coughs, lifts head off pillowMorbid ObesityShort NeckImmobile neckAnterior Mandibular Space < 6 cmSize of TongueFacial Fractures (Wired Mandible, Facial / oropharyngeal edema)Previous failed intubationsHistory of tracheotomy / tracheostomyHave re-intubation tray at bedside.Have a surgical attending present.Stop all continuous gtt sedation and opiates post extubation.  Consider replacing analgesic gtt with PCA if unable to take p.o.Consider swallow study if patient has been intubated for more than 5 days or if neurologically compromisedMonitor patient closely in ICU for at least 4 hours after extubation prior to any disposition elsewhere.