Grand Rounds Recap 7.7.21
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Airway Management of the Neurocritically Ill WITH Neurocritical Care fellow, Dr. Jared Ham
Neurocritical causes of ‘failure to oxygenate and ventilate’
Patients with neuromuscular disorders, spinal cord injuries, status epilepticus, or postictal patients who have received multiple doses of benzodiazepines may have particular difficulty with oxygenation and ventilation
Neurocritical causes of ‘failure to protect’
Post midbrain stroke patients with residual bulbar dysfunction
Patients with significant craniofacial trauma who may have altered anatomy
Patients with post TPA angioedema
Patients with a GCS less than 8 (especially in non-trauma patients)
Interestingly, about ⅓ of patients with a normal GCS have a poor gag reflex, and about ⅓ of patients with a GCS less than 8 have a normal gag reflex.
Indications for intubation based on clinical course in neurocritical patients
May need intubation to assist with critical imaging such as an MRI or to provide safe transport to a definitive care facility, especially when these patients are flying long distances.
Intubating the neurocritically ill
Controlling Cerebral Blood Flow
Maintain normoxia and eucapnia.
Maintain cerebrally perfusing hemodynamics (systolic BP goal of 110-140 seems to have the lowest mortality, with hypertension having a lower mortality than hypotension). You may need to augment blood pressure with IVF or pressors, particularly in patients with disorders such as spinal shock.
Even brief episodes of hypoxia and hypotension with a systolic BP less than 90 can lead to an increase in mortality by 50% in the neurocritically ill.
Controlling Intracranial pressure and cerebral perfusion pressure
Position the patient in reverse trendelenburg to allow gravity to assist in draining CSF.
The direct laryngeal reflex - manipulation of the posterior oropharynx can activate the direct laryngeal reflex resulting in an elevated ICP. Careful handling of the laryngoscope, and topical application of lidocaine to the posterior pharynx can minimize activation of the direct laryngeal reflex.
Pretreatment in intubation of neurocritical patients
Consider pretreatment with fentanyl or hypertonic saline. IV Lidocaine may cause hypotension which could be detrimental, and is therefore no longer routinely used for pretreatment when intubating neurocritically ill patients.
Drug choices for induction, paralysis, and post intubation-sedation in neurocritcally ill patients
Dr. Ham’s preferred choice for induction in the neurocritically ill is ketamine - the concerns about ICP are not supported, and it may actually raise blood pressure and prevent peri-intubation hypotension
The QI/KT from April by Drs. Frankenfeld and Ijaz provided evidence that propofol may be better in the status epilepticus patient, as long as their hemodynamics can tolerate the use of propofol (see more details here)
Rocuronium vs Succinylcholine - remains heavily debated. Succinylcholine is typically avoided in patients with neuromuscular disorders. Although rocuronium does last longer and therefore clouds the neurologic exam for longer, when needed sugammadex can be utilized for prompt reversal.
Propofol is a nice choice for post-intubation sedation in the status epilepticus patient and is quick on/quick off, which allows for frequent re-evaluation of a patient’s neuro status without creating long periods of inadequate sedation
Unstable Cervical Injuries
Avoid Hypotension to minimize further damage to the spinal cord
Avoid further displacement of the spinal column, maintain in-line stabilization, and use specialized airway equipment as necessary (consider video laryngoscopy). The BURP maneuver may risk further spinal displacement and should be avoided.
Ultrasound Grand Rounds: Cardiac Ultrasound WITH Ultrasound Director, Dr. Lori Stolz
Don’t settle: don’t settle for suboptimal windows or non standard views. These images hamper the development of your ultrasound skills and interpretation of suboptimal images can be misleading. Always center your image in the center of the window to optimize image quality.
Pericardial Effusion vs Fat Pad
Fat pads usually are echogenic, are usually anterior only, and usually do not change in size throughout the cardiac cycle
Pericardial effusions are usually anechoic, are usually posterior, are usually largest during systole, and usually circumferential if large.
Note the use of ‘usually’, this is why these entities can be difficult to differentiate.
Findings of cardiac tamponade on ultrasound
Pericardial Effusion plus …
Right atrial collapse during ventricular systole (valves closed, right atrial collapse)
This is the lowest pressure chamber of the heart and is therefore an early finding of tamponade. This finding is highly sensitive.
Inversion of the right atrial wall for < 1/3 of the cardiac cycle is not diagnostic of tamponade and can be physiologically normal.
Right ventricular collapse during ventricular diastole (valves open, right ventricular collapse)
You can use M-mode in parasternal long view to more easily evaluate for RV collapse and coordinate it with mitral valve movement.
Exaggerated Respiratory Variation
Tamponade is a state of poor filling. Respiration normally aids in filling the heart. In tamponade, we become even more dependent on respiration to fill the ventricles.
The right side of the heart fills better with inspiration, and the left side of the heart fills better with expiration. Furthermore, the right side of the heart is more dependent on respiration for filling.
More than a 40% difference in flow at the tricuspid valve between inspiration and expiration, and more than 25% difference in the flow at the mitral valve between inspiration and expiration, is indicative of tamponade.
Plethoric IVC
The IVC is also very dependent on the respiratory cycle. A flat, highly collapsible IVC can essentially rule out tamponade (97%), whereas a plethoric, distended, non-varying IVC can be suggestive of tamponade (although this is not specific)
Evaluation of LV function
The eyeball method (EF = (EDV-ESV)/EDV )
A study in the International Journal of Cardiology (2005) demonstrated that visual estimates of EF by cardiologists correlated well with objective measurements
Another study in Academic Emergency Medicine compared emergency physician visual estimation to cardiology visual estimate and objective measurements, and found that emergency physicians were also able to visually estimate EF well
Pitfalls of EF estimation
You need 2 views (with good images and good alignment) to effectively estimate EF
Remember you can have heart failure with preserved EF
Wall motion abnormalities and bundle branch blocks can significantly impact your ability to accurately estimate EF
Bradycardic hearts tend to look worse than they actually are, Tachycardic hearts tend to look better than they actually are.
MV EPSS
MV EPSS is a fairly accurate measurement of LVEF
<7 mm is normal, 8-10 mm is mild to moderately depressed, >10mm is a severely depressed EPSS
EKG Poutpourri WITH Dr. Lang
OMI/NOMI vs STEMI/NSTEMI
The original definition of an MI was q-wave MI or non-q-wave MI. This definition was replaced by STEMI/NSTEMI around 2000. There is now a push, in the era of revascularization therapy, to change from STEMI/NSTEMI definition to OMI/NOMI (Occlusive MI/Non-occlusive MI). The push comes from the fact that the current definition of STEMI misses patients who would benefit from early percutaneous intervention.
The STEMI definition misses about 25-30% of occlusive myocardial infarctions
Patients with occlusive myocardial infarctions who do not meet STEMI criteria have worse outcomes than their true STEMI counterparts, likely due to the delayed revascularization despite an occlusive event.
The definition of OMI is an occlusion or near occlusion of a coronary artery with insufficient collateral blood supply, such that without intervention the affected myocardium will die. This would include STEMIs, but also expand the utilization of revascularization to certain non-STEMI patients.
OMI ECG Criteria
OMI ECG criteria expands from the current STEMI criteria to include other ischemic changes. Many of these we have been classifying as early ischemic findings and ‘subtle STEMIs’ for many years. Among these are:
ST elevations, even subtle ones that do not meet standard STEMI criteria, in two contiguous leads
Hyperacute T waves including Dewinter’s Waves
Reciprocal ST depressions and/or negative hyperacute T waves
Maximal ST depression in V1-V4
Acute Pathological Q waves
Terminal QRS Distortion
Subtle inferior ST elevation
Modified Sgarbossa in patients with LBBB and V-paced patients
Ischemia mimics
Pericarditis - Presents with diffuse ST elevation, diffuse PR depressions, and ST depression and PR elevation in aVR
Can additionally see q waves when concomitant myocarditis
Benign Early Repolarization - Diffuse, concave, ST Elevations. Ratio of STE:T wave < 0.25. Typically present in patients under 50 years of age.
Hyperkalemia - presents with peaked T waves, prolonged QRS, flattened P waves.
LVH - ST depression and T wave inversion in I, aVL, and V5-V6.
Airway Grand Rounds WITH Dr. Carleton
I-gel Placement Assessment
The patient’s head needs to be in the sniffing position when placing the igel, and then maintained in a neutral position once the igel is in place. The patient’s head needs to be midline and the Igel should be midline within the mouth.
A study conducted in patients in the operating room found that initial igel placement was optimal in only 57% of patients. Additionally,optimal placement degraded to incorrect placement in 27% of patients after only 1 hour of use. (Moustafa and Abdelhadi, Journal of Clinical Anesthesia 2014)
In many patients, the tip of the epiglottis comes in contact with the posterior pharyngeal wall when the patient is in the supine position. This unfortunately primes the Igel to catch on the tip of the epiglottis and slide in front of the epiglottis, causing it to become mal-positioned in front of the airway. To avoid this, perform a jaw thrust as you place the Igel. This will lift the epiglottis up and away from the posterior pharyngeal wall, allowing the Igel to properly seat behind it in the posterior pharynx.
The Igel has an index line which should line up with the patient’s teeth when in the correct position
EtCO2 monitoring and laryngoscopy/endoscopy are the most accurate means of confirming appropriate location.
Optimizing your igel
Once Placement is confirmed, anchor the Igel in place to maintain adequate position
Decompress the stomach with a gastric tube
A 12 french feeding tube fits down size 3-5 igel with lubrication.
Ventilate the patient, avoiding peak inspiratory pressures > 20-25 cm H2O
Suction as needed
Converting the Extraglottic Device (EGD) to a definitive airway
Some options to convert the EGD to a definitive airway include removing the EGD and intubating by video laryngoscopy or direct laryngoscopy, intubating around the EGD by video or direct laryngoscopy, or performing a surgical airway with an EGD in place.
The preferred options are blind intubation through an EGD (which has a success rate in the 70s), or endoscopic intubation through the EGD (has a 96% success rate for 1st past intubations). To perform intubation through the Igel:
Step 1: Place the ETT partly through the Igel and inflate the balloon within the lumen of igel to create a seal.
Step 2: Attach the BVM or ventilator to the ETT in the igel to ventilate and preoxygenate the patient.
Step 3: Once you are ready to intubate, feed the endoscope through the ETT and visualize the cords, advance the endoscope to the point just proximal to the carina
Note that a bronchoscopy port can be utilized for this so that the patient can be bagged throughout the entirety of the procedure.
Step 4: Deflate the ETT cuff and advance the ETT over the endoscope.
Step 5: Remove the Igel, then remove the endoscope, visualizing placement of the ETT as you withdraw the endoscope.
Step 6: Inflate the ETT balloon and secure the ETT.
Aintree Intubation Catheter - A semi rigid ventilation catheter that fits through an igel or ETT, but over a standard fiberoptic bronchoscope.
Step 1: Load the Aintree catheter onto the endoscope/bronchoscope and temporarily anchor it to the endoscope.
Step 2: Advance the endoscope with the Aintree catheter into the igel using the visual guidance of the endoscope.
Step 3: Remove the endoscope, leaving the Aintree catheter in place within the trachea and the lumen of the Igel.
Step 4: Remove the LMA and leave the Aintree catheter in place.
Step 5: Load the ETT over the Aintree catheter.
Step 6: Reintroduce the endoscope/bronchoscope into the Aintree catheter
Step 7: Advance the ETT into the trachea while securely holding the Aintree catheter in place
September 8: Remove the Aintree catheter and confirm ETT placement with EtCO2.
Consultant’s Corner: Difficult Airways WITH ENT, Dr. PATIL
The difficult airway - a clinical situation in which a conventionally trained physician experiences difficulty with face mask ventilation and.or tracheal intubation
Evaluating for a difficult airway
Go through the same steps on every patient, every time. Have an algorithm so you don’t miss anything
T’s - Tumor, tilt, trauma, teeth, tracheal scar or tracheal resection, tongue, thyromental distance, trismus
LEMON
Look at external airway, head, and neck anatomy
Evaluate 3-3-2 (3 finger mouth opening, 3 finger distance from the mentum to the hyoid bone, 2 fingers from the hyoid to the thyroid)
Mallampati
Obstruction or Obesity
Neck Mobility
Prepare your team and verbalize your plan
Identify predictors of difficulty to the rest of the team before induction. Verbalize your plan, intended equipment, and initial plans for backups and rescue devices.
Acknowledging the current intubation plan isn’t working
When you cannot get a DASH-1a (Definitive airway sans hypoxia- 1st attempt) airway, before your re-attempt, you need to decide what you will do differently to make your next pass successful.
Change the patient or provider position
Change the device you are using (use a video laryngoscope, change to a hyperangulated video blade, use a bougie for assistance, use an Aintree intubation catheter, utilize a fiberoptic scope, retrograde intubation)
Lastly, change the provider attempting to intubate
Can’t intubate and can’t oxygenate
The final pathway in difficult airways. When you cannot successfully intubate and are not able to successfully oxygenate the patient
You are forced to act.
In the emergency department we progress to a cricothyrotomy at this point. The patient can be very briefly temporized with jet ventilation.
