Hypoxia Despite Ventilation

Hypoxia Despite Ventilation


A proper path to RSI

Dr Jordan Singer

An ALS crew was dispatched to a single vehicle MVC.  The car was found just off the road and had hit a fence post with minimal damage to the vehicle.  Airbags had not deployed, no passenger compartment intrusion, no deformity to the steering wheel and no damage to the windshield.  The patient was found in the driver’s seat and was unresponsive with no obvious signs of trauma.  The crew noticed the patient was wearing a NC connected to an O2 concentrator in the passenger’s seat.  The patient was found breathing agonally.  The crew leaned back the drivers’s seat to access the patient better and started BVM ventilations.  Patient was found to be cyanotic, cool, and clammy, but had an intact radial pulse.  The crew rapidly extricated the patient to the ambulance.


In the ambulance, the crew continued to assess and resuscitate.  The crew tried to place an OPA but the patient would gag and bite down.  Initial set of vitals were:


Vitals: strong pulse, HR 40,  RR 18 (with BVM), Sat 60%,  ETCO2 55mmHg,  Glucose 220


The crew initiated transport to the hospital.  They obtained an IV while obtaining the above vitals and gave atropine for the bradycardia.  Given minimal damage to the vehicle and no signs of trauma, the crew suspected a medical cause of the crash and suspected that the unresponsiveness was due to respiratory failure from a medical cause as opposed to a traumatic cause.  The crew attempted to reposition the patient to improve oxygenation with BVM but was unable to get the sat above the mid 80s with BLS airway techniques.  The crew considered a supraglottic airway, but the patient had a gag and a clenched jaw preventing the use of one of these devices.  The crew decided to perform RSI on this patient.  They utilized their RSI checklist to ensure everything, including back up plans, were set up and they obtained another set of vitals before pushing meds:


Vitals: BP 156/90,  HR 137  RR 12 (with BVM),  Sat 88%, ETCO2 55mHg


Crew administered a sedative and a paralytic.  The crew was able to bag the patient up to a sat of 95% after meds were pushed before making an intubation attempt.  Cords were unable to be visualized so the first attempt was aborted.  The patient was bagged again, and the crew re-positioned the patient by adding padding under the head to improve airway alignment for the second attempt.  A different medic attempted the second intubation and was able to successfully place the tube.  Tube placement was confirmed with waveform ETCO2.  The crew noted with auscultation that there was only breath sounds on the right pointing towards the tube being in the right mainstem.  The tube was retracted 2cm leading to breath sounds being heard bilaterally and the ETCO2 waveform remained telling the crew the tube was not pulled out too far.  Vitals were re-assessed post RSI:


Vitals: BP 195/130,  HR 140  RR 16 (with BVM),  Sat 96%, ETCO2 125mHg


The crew re-sedated the patient shortly after obtaining vitals to make sure there was no time that the patient was paralyzed but not sedated.  The patient continued to improve during the transport and was handed off to the receiving facility in stable condition. 



Highlights of the case:

Medical emergencies can cause traumas.

This crew was dispatched to a patient who was found unresponsive after an MVC.  In the setting of a traumatic mechanism, the first, second and third thing on our differential diagnosis should be trauma.  However, if there is evidence pointing towards a medical issue, we should consider that as well.  In this case, the crew found a patient in respiratory failure with minimal damage to his car and no signs of trauma.  This points towards a medical emergency, such as respiratory arrest from a COPD exacerbation, as the more likely cause of the patient’s presentation.  While this does not rule out trauma, it points away from trauma being the primary issue.  Respiratory failure in the setting of trauma is often either from a head bleed causing hypoventilation or from a pneumothorax or hemothorax.  In this case, tension pneumothorax seemed less likely and the crew did the right thing not performing needle decompression.


If a patient is bradycardic, treat the underlying cause of the bradycardia.

This patient became bradycardic while the patient was profoundly hypoxic.  Hypoxia causes bradycardia because not enough oxygen is being delivered to the heart which causes it to slow down.  If the hypoxia is not corrected, the patient will continue to become more bradycardic until the patient arrests.  While the crew treated the patient with atropine, that will not fix the underlying issue and the patient will remain bradycardic.  The reason that the bradycardia eventually resolved was because the crew utilized great BLS airway techniques and was able to bag the patient to a sat in the 80s which led to resolution of the bradycardia.  Other causes of bradycardia is complete heart block and increased vagal tone.  If the patient is bradycardic from complete heart block, we would treat the patient with transcutaneous pacing.  If the patient were bradycardic from increased vagal tone, that would be the time that we would treat the patient with atropine.


If unable to ventilate and/or oxygenate the patient, we should consider RSI

This crew tried everything they could to oxygenate and ventilate the patient with BLS techniques including positioning as well as airway adjuncts.  They considered a supraglottic airway but could not use it given the trismus and intact gag reflex.  Use of RSI was very reasonable here.  Intubation is a dangerous time for the patient since tons of things can go wrong and we have very little time to address them if they do go wrong.  For this reason, we want to prepare as much as possible in advance.  This includes anticipating everything that can go wrong and preparing for these things.  Our RSI drug boxes have a laminated copy of our RSI check-list that lists all the things we need to have ready before we perform RSI.  This is also listed in our protocol and we want to utilize this every time we intubate so that our intubation attempts go as smoothly as possible.  This crew had everything planned out and prepared in advance which made a very difficult intubation go as smoothly as possible.


If the first intubation attempt is not successful, modify something.

We might not always be successful during every intubation attempt we make.  The key thing to remember is that we need to do something different on the subsequent attempt since if we do everything in the exact same way, we are very likely to be unsuccessful the second time.  Your first attempt should give you insight to what is going on in their airway to help guide this change.  You can consider using a different size tube, using a different size blade, repositioning the patient, or changing the intubator.  You can also decide to utilize a supraglottic for the second attempt if the concern is that the patient is dropping his/her oxygen saturation too fast for you to place the endotracheal tube.  You are allowed to change multiple things if you think that is needed, but the key is that you need to change something.  This crew repositioned the patient and changed intubators and was able to get the endotracheal tube placed quickly on the second attempt.


Always check to ensure that the endotracheal tube is in the right place and not in too deep.

Once we think we have successfully placed an endotracheal tube paced cords, we need to confirm that we area indeed in the airway, but also that we are not too deep.  The most important thing is to confirm that we have waveform ETCO2 showing waveforms that correlate 1:1 with each breath we give the patient.  If this is present, you can be certain that you are in the trachea.  While you can document other findings that support that the endotracheal tube is in the correct position, these findings need to be in addition to using waveform ETCO2 and should never replace waveform ETCO2.  In addition, we need to make sure that we have not placed the endotracheal tube too deep and are only ventilating one lung.  By listening to both sides of the chest and confirming that we hear breath sounds bilaterally, we can confirm that the tube is not in either mainstem bronchus.  This crew confirmed that the tube was in the airway with waveform ETCO2 but only heard breath sounds on the right pointing towards the tube being in too deep.  The correctly re-positioned the tube and ensured they did not come out too far by ensuring that the ETCO2 waveform remained present after re-positioning the tube.