#362 Migraine Headaches, Acute Hypoxemia: A rapid review (TFTC)

October 26, 2022 | By Matthew Watto, MD

Video

Recap and review the top pearls from recent episodes #341 Migraine Headaches Update and #350 Acute Hypoxemia with Watto and Paul. It’s Tales from the Curbside! (TFTC), our monthly series providing a rapid review of recent Curbsiders episodes for your spaced learning.

Note No CME for this mini-episode but visit curbsiders.vcuhealth.org to claim credit for shows #341 and #350!

Episodes | Subscribe | Spotify | Swag! | Mailing List | askcurbsiders@gmail.com | Free CME!

Show Segments

• Intro, disclaimer, guest bio
• Migraine Headaches Update
• An approach to Hypoxemia
• Outro

Credits

• Written, Produced, and Hosted by: Matthew Watto MD, FACP; Paul Williams MD, FACP  
• Show Notes: Matthew Watto MD, FACP
• TFTC Cover Art design: Edison Jyang
• Technical Production: Pod Paste

Episode #341 Headache Update

Featuring Kevin Weber of OSU, production by Chris Chiu and Isabel Valdez, and graphics by Edison Jyang

Diagnosis

Headaches can be classified as migraine, tension-type, and other. The latter group warrants a neurologist or headache specialist. 

Headache red flags include (but are not limited to) a history of malignancy, headache plus fever, age of onset over 50, positional headache, sudden or abrupt onset, and change in severity or frequency. Use the SNNOOP10 mnemonic to identify patients who might have a secondary cause of the headache and thus, warrant neuroimaging (Phu Do, 2019). MRI of the brain without contrast is adequate imaging for most unless malignancy or CSF leak is suspected.

Dr. Weber asks about cervical symptoms because in his expert opinion many patients with chronic migraine headaches have a cervicogenic component. He treats with physical therapy.

Patient counseling

Dr. Weber said, “I tell my patients to think about migraine like it’s an irritable old miser set in their ways and your brain is set in its ways, and doesn’t like changes in routine. It doesn’t like lack of sleep, it doesn’t like being hungry, it doesn’t like being thirsty, it doesn’t like changes in the weather.”

Abortive Migraine therapies

It’s okay to take OTC abortive medications (acetaminophen, NSAIDS, and aspirin/acetaminophen/caffeine) along with triptans, ditans, and gepants (expert opinion). 

Dr. Weber likes rizatriptan and naratriptan because they are both generic and have fewer side effects than sumatriptan (expert opinion). Rizatriptan has a quicker onset of action while naratriptan has a longer duration of action but slower onset. Don’t forget to warn your patients that triptans may cause chest tightness as a common side effect! In general, avoid triptans in patients with known cardiac or cerebrovascular disease. However, the concern for serotonin syndrome has not been seen in practice (Michelle Kerr, Daniel Krashin, Natalia Murinova

Neurology Apr 2019, 92 (15 Supplement) S27.005)

The newer CGRP-receptor blockers and ditans can be used in patients with vascular disease (unlike triptans)! CGRP-receptor blockers can be abortive (like ubrogepant twice daily or rimegepant once daily by mouth) or preventative (rimegepant every other day or Atogepant daily oral or injectable monoclonal CGRP medications like fremanezumab, erenumab, and galcanezumab or eptinezumab via injection or infusion). Lasmiditan works much like triptan for abortive treatment without causing vasoconstriction but comes with an 8-hour driving restriction!

Preventive migraine therapies

It’s well within the wheelhouse of a primary care doc to trial preventive medication for migraine headaches. Many medications can be dual-purposed based on a patient’s other medical conditions e.g. hypertension, depression, obesity, chronic pain.

• Antihypertensive: beta-blockers-metoprolol, nadolol, atenolol; ARB-candesartan (Dorosch 2019); CCB-verapamil (Markley 1991)
• Anti-seizures agents: topiramate, valproic acid
• Tricyclic antidepressants: amitriptyline, nortriptyline
• SNRI: venlafaxine (Ozyalcin 2005)

Kashlak Pearl: Dr. Weber notes that most insurance companies want patients to have tried two abortive therapies or preventive therapies before approving the newer and more expensive agents like gepants, ditans, CGRP monoclonal antibodies. It helps to give medical contraindications for specific therapies (e.g., low blood pressure, history of kidney stones, etc.).

Alternative therapies

Magnesium supplements are safe and seem to be effective for migraine prevention (von Luckner, 2018). A few different modalities for neuromodulation have been approved, but the cost is a barrier. One device is available OTC as a sticker that attaches to the forehead and stimulates the supraorbital nerve. 

Episode #350 Acute Hypoxemia

Featuring Nick Mark of the OHSU, production by Cyrus Askin, and graphics by Edison Jyang

• Hypoxemia: Low oxygen in the blood, measured with a pulse oximeter or blood gas.
• Hypoxia: Low levels of oxygen at the tissue level.
• Oxygen content: How much oxygen is carried in the blood. 
• Oxygen delivery: The product of oxygen content and cardiac output (CO). This is how much oxygen is making it to the peripheral tissues.

Kashlak Pearls: 

• Pulse oximeters are inaccurate below 70% because of ethical limitations in the original studies. 
• Changes in pulse oximeter readings from supplemental O2 trail the actual saturation as it takes newly oxygenated blood about 30 seconds to reach the periphery!

The patient with acute hypoxemia

• First, ask “sick or not sick?”. Tripoding, poor mental status, and using accessing muscles are bad signs
• Note: Whether or not a patient is “protecting their airway” is kind of like pornography; you know it when you see it. 
• Next, sit the patient up in bed, place them on supplemental oxygen, assess for a reliable pulse oximeter waveform. 
• Perform a targeted history and physical exam, which might include the use of POCUS to look for pneumothorax, pulmonary edema, and evidence of abnormal cardiac function/pressures. 

The differential diagnosis (Six buckets)

1. Low inspired oxygen content – typically seen at altitude
2. Alveolar Hypoventilation – mechanical restriction (trauma/pain), neuromuscular restriction, obstructive lung disease
3. Low Mixed Venous Oxygen Concentration – Causes: Severe anemia, low cardiac output, extremely high oxygen utilization
4. V/Q Mismatch – an imbalance between perfusion and ventilation
5. Shunt – Does not correct with supplemental O2! Note: initiation of nitrates and CCB can cause shunting!
6. Diffusion Limitation – minimally present at rest, much more noticeable during exertion/stress

Differentiate between the six buckets of hypoxemia using the A-a gradient (aka A-a difference)!

• Normal A-a gradient: Low inspired oxygen content, hypoventilation, low mixed venous oxygen content
• Elevated A-a gradient: Pulmonary cause for hypoxemia – V/Q mismatch, shunt or diffusion limitation

Goal

Listeners will recall key pearls from recent Curbsiders episodes

Learning objectives

After listening to this episode listeners will…

1. Update their approach to migraine headaches
2. Recall key pearls about the diagnosis and management of acute hypoxemia

Disclosures

The Curbsiders report no relevant financial disclosures. 

Citation

Williams PN, Watto MF. “#362 Migraine Headaches, Acute Hypoxemia: A Rapid Review (TFTC)”. The Curbsiders Internal Medicine Podcast. http://thecurbsiders.com/episode-list Final publishing date October 26, 2022.