Week 1: Day 2

Good morning from Charlottesville!

I've decided to use this blog to record my daily activities so I can remember details once I'm done with my month here. So, here we go:

Day 1 - already posted video about it.

Day 2

Activities

- 7:15 AM rounds in the PICU. I understood so much more of these due to my frantic searching of terms I'd scribbled down the day before during the 3 hours of rounds I attended. See below for said list.

- Cardiothoracic surgical conference - this is a weekly conference where all the upcoming surgeries are discussed with cardiologists and cardiac surgeons to make sure everyone is on the same page. The part where they pulled up the videos of echos (ultrasounds of the heart) made me giggle inside because it literally looked like weather to me. As in, they overlaid colors to highlight something or other and it legitimately looked like a meteorological report on the evening news. Aaahhh, how far I have to go...

See? Weather. (Courtesy of LSU)

- AM rounds on the pediatrics floor. This is where "averagely-sick" kids stay. Usually after heart surgery, the kid will be placed in the PICU, and the goal is to get him/her well enough to be transferred as soon as possible to the floor. Less time in the ICU = less risk to the kid and a bunch of other things too (usually a shorter hospital stay in general; less expensive; more comfortable for the family).

- Worked on literature search for post-op clinical pathways project that I'm helping with. If all goes well I should be listed as co-investigator, which means I should eventually be published (a first for me). Lots to do between now and then.

- Took a long walk around grounds (UVA's version of campus) after work because it was about 60 degrees outside. Got home, showered, ate dinner, and passed out at 7:30 pm. No joke.

Terms to look up (all you friends in med school / residency, don't laugh at me, and feel free to correct any errors or fill in blanks):

Amnio IV

"Put cannula on blender" - I think this refers to delivering mixed air/O2 to the baby as opposed to pure O2. Kids with hypoplastic left heart syndrome (HLHS) can't be delivered pure oxygen because too much oxygen in the blood would decrease PVR (pulmonary vascular resistance, i.e., blood pressure in the lungs), thus sending more blood from systemic circulation to the lungs. Overcirculation of the lungs eventually leads to congestive heart failure.

This brings up a question about PVR and systemic vascular resistance (SVR), and why it's so critical to maintain a balance between the two for HLHS patients. Here's my (overly simplified) attempt at answering that:

First of all, HLHS is a condition in which a baby is born with a very small or nonexistent left ventricle, a stenosed (narrowed) aorta, and various other issues. Shortly after birth, there is no effective way for the heart to pump oxygenated blood to the body because of the condition of the LV (although for a brief amount of time, the baby can survive as long as the ductus arteriosus, a blood vessel providing a conduit between the aorta and the pulmonary artery, is patent [i.e., open]. Until surgery, the DA is kept patent drugs called prostaglandins). Three palliative surgeries are available to enable the kid to live until he can get a heart transplant. I'm most familiar with the Norwood procedure so far (1st of the 3), so will restrict my discussion to that one.

Normal heart vs. HLHS heart (courtesy of Wikipedia)

If oxygen levels are decreased through the cannula, the pO2 in alveolar spaces will decrease. If pO2 in the alveoli decreases, pulmonary vasoconstriction occurs (this diverts blood to alveoli with a higher oxygen content), which results in an increase in PVR. Likewise, if oxygen levels are increased via the cannula, PVR will drop and more blood will circulate through the lungs.

Balancing PVR with SVR is critical to balance blood flow to the lungs and the rest of the body during recovery from a Norwood. First of all, during the surgery, the main pulmonary artery is totally disconnected from the right ventricle, and instead the aorta (surgically widened from its original stenosed form) is made into the main pathway out of the right ventricle. Blood goes out the right ventricle through the reconstructed aorta, and can either go a) out the aorta to the rest of the body, or b) through a shunt (Blalock-Taussig, or BT) that is connected from the subclavian artery to the pulmonary artery, and proceed to the lungs (another option is the Sano shunt, where the tubing directly connects the right ventricle to the pulmonary artery). In this way, the RV becomes the provider of blood to both the lungs and the body, whereas in a normal heart, the RV sends blood to the lungs, and the LV sends blood to the body. Naturally, if the pressure is too great in either the pulmonary or the systemic vasculature, the blood will take the "easier" path of the two, and either the lungs or the body will get too much blood relative to the other.

If too much blood goes to the lungs, the blood gets "backed up" in the heart and leads to congestive heart failure. If not enough blood gets to the lungs, the rest of the body won't get enough oxygen. And this is just one reason why HLHS patients are so tricky to keep alive.

FFP - not sure on the context of this one, but could refer to fresh frozen plasma, which is used in infants with secondary immunodeficiency (which could be caused by certain medications or infections) associated with protein-losing enteropathy (when proteins can't be absorbed in the digestive tract, or are being lost from the digestive tract).

RV failure - failure of the heart's right ventricle

Respiratory acidosis - occurs when lungs can't remove enough CO2, so the blood becomes too acidic. FLASHBACK TO PHYSIOLOGY PROBLEM SET / nerd alert: "Because the blood cannot effectively get rid of CO₂, this carbon dioxide will react with water to form carbonic acid and then bicarbonate and protons, causing pH in the blood to decrease and the equation CO₂ + H₂O -->  H₂CO₃ --> HCO₃^- + H⁺ to shift right according to le Chatelier’s principle. Chemoreceptors in the carotid artery and aortic arch will alert the integrator in the medulla oblongata of these acidic pH levels. The integrator will compare these values to the blood’s preferred pH set point and conclude that the pH levels in the blood are too low. The integrator will use sympathetic efferent nerve fibers to release neurotransmitters (e.g., epinephrine), which bind to receptors on effector cells and cause breathing rate to increase, inducing hyperventilation to rid the blood of CO₂."

Why a nosebleed is a strike against extubation, and why vitamin K might help this

Calcium drip (what does this target?)

Diuril (drug) - diuretic used to manage congestive heart failure

RVPA conduit (right ventricle-to-pulmonary artery conduit)

VACTERL - an association of birth defects having some or all of the following: vertebral anomalies, anal atresia, cardiovascular anomalies, tracheoesophageal fistula, renal anomalies, limb defects

Aldactone/spironolactone (drug) - diuretic / anti-hypertensive

ASD-VSD closure - procedure in which atrial septal defect and ventricular septal defect are closed

Nicardipine hydrochloride - calcium channel blocker used to treat high blood pressure and angina

Amikacin (drug) - Antibiotic that binds to bacterium's ribosomal subunit so mRNA is misread and bacterium can't make proteins needed for growth

MSSA - bacterium (methicillin sensitive staph aureus, as opposed to MRSA, methicillin-resistant staph aureus, which aren't killed by first line antibiotics used to treat staph infections)

ARDS - acute respiratory distress syndrome; lung condition preventing enough O2 from getting to the lungs and into the blood

Noonan syndrome - congenital disorder affecting various parts of the body, including the heart; causes pulmonary valve stenosis (narrowing), can also cause atrial septal defect (ASD) and hypertrophic cardiomyopathy (HCM - thickening of heart muscle)

BMP - basic metabolic profile; blood test used to measure things like fluid and electrolyte status, kidney function, blood sugar levels

That's it for day 2. Here is my life when I'm not on rounds or researching clinical pathways: