Vena-cava

“Of Beren and Lúthien”

Today is Tolkien Reading Day, so it can’t have been coincidence that on this very day I came across the beautiful fanfic Vena Cava by SilentAuror which inspired the drawing above: John reading the Silmarillion to Sherlock as he’s recovering from his gunshot wound. I look forward to reading more from this author :).

Eeee, omg! My fic Vena Cava just reached 40,000 hits today! This is only the second one of my stories to have achieved this milestone (the first is Best of Three). It currently has 474 comments (though half are my responses!), 997 bookmarks (772 public), and 1,950 kudos. Of the many series 3 fix-it fics I’ve written, this is still one of my very favourites. I based scenes of my original novel on this story. Thank you so much for every single one of these hits and for all of your comments and bookmarks and kudos and love! You guys are so great! <333333333333333333333333333333333333333333333333333

Pregnancy - physiology

Hormones

  • hCG - human chorionic gonadotropin - present in blood and urine, produced by blastocyst and placenta
  • Low levels of hCG could mean miscarriage, ectopic pregnancy, miscalculation of dates
  • High levels = molar pregnancy (cells that normally form a baby dysfunction and form cysts instead), multiple pregnancy (twins etc), miscalculation of dates
  • Progesterone increases fat deposition in early weeks and stimulates appetite
  • Increased oestrogen from corpus luteum promotes mammary gland development (breasts enlarge)
  • And inhibits ovulation via negative feedback [OES decreases GnRH release by hypothalamus –> linhibition of FHS and LH –> no ovulation]
  • Relaxin (secreted by corpus luteum) softens connective tissue in preparation for labour - not specific, all joints can be affected
  • Peaks in early and late pregnancy

Physical changes

Blood pressure

  • As early as 4 weeks into pregnancy 
  • plasma volume increase
  • caused by the affects of oestrogen and progesterone on the kidneys

OES and Prg cause vasodilation 

  • less resistance = less pressure
  • Heart rate increases by 25% to compensate
  • stroke volume increases 
  • increased overall cardiac output by 50% in third trimester

Direct action of enlarged uterus:

  • compresses the descending aorta and inferior vena cava 
  • decreased venous return - less blood in means less blood out, less blood in ventricle –> reduced pressure on walls –> reduced force to exit –> reduced placental perfusion
  • increased aortic pressure
  • increased heart rate
  • [shouldn’t sleep on back for this reason]

Outcomes:

  • Fall in blood pressure (can cause collapse if serious)
  • Can cause foetal hypoxia even without mother symptoms

Haematological changes

  • red cell mass increase by 20% (renal - increased erythropoietin production in response to detection of blood oxygenation and sodium/water balance)
  • Plasma volume increases more than RBC count does, causing the impression of decreased haemoglobin (anaemia)
  • Increased tendency to clot (hypercoagulable)
  • due to increase in clotting factors and plasma fibrinogen
  • platelet production increase (however count drops due to increase in activity and consumption) - function remains normal]
  • WBC count may increase due to an increase in granulocytes

Respiratory changes

  • Increased chest diameter, diaphragmatic expression and elevation
  • dyspnoea common (difficulty breathing)
  • breathing becomes more costal (mouth) than abdominal 
  • mainly mediated by progesterone levels (cause bronchial and smooth muscle relaxation and hypersensitivity to CO2)

Changes to the urinary system

  • cardiac output increase –> increase in renal plasma flow and glomerular filtration
  • increase in urea, creatinine, urate and biocarbonate clearance 
  • with progesterone, renin and aldosterone up water retention increases
  • can lead to urinary stasis and increased risk of UTI
  • Any drugs given that are excreted renally must be given in much higher quantities consequently

Gastrointestinal changes

  • Appetite increase + cravings 
  • Gastric reflux sphincter relaxation (increased indigestion, also due to increased intra-gastric pressure (expanding uterus)) 
  • gallbladder dilated 
  • GI motility decreased and transit time slower 
  • albumin and protein decrease 
  • cholesterol twice normal value

Muskuloskeletal 

  • Calcium reuptake into bloodstream results in mild decalcification of bones 
  • relaxin softens joints (pubic symphysis + alters gait (waddling))
  • abdominal muscles stretch to elastic limit 
  • stretch marks (stria gravidarum) caused by rupture of elastic fibres and small blood vessels 

Reproductive changes

  • Massive increase in mass
  • Placenta growth (nutrition, excretion, immunity, endocrine) 

Parental blood supply 

What I Learned on My Food Animal Medicine and Surgery Rotation

-          You should always wear earbuds when working with pigs. They can be LOUD.

-          Apparently I have zero cognitive function when checking on ICU patients at 4am in the morning. Go figure.

-          You could probably take a cow’s intestine out, step on it with muddy boots, put it back in, and it would be fine.  They are hardy little critters.

-          Don’t EVER take off needle caps with your mouth, or touch your mouth with poopy hands while working with cows. You will get crypto (fecal-oral zoonotic disease that will give you the poops for week), and you will die. (not really but you will want to die).

-          A rectal palpation (to check pregnancy or other organ status) is not as gross as you think, but is way harder than you think (“Is that squishy thing the cervix or the rumen? What about the other squishy thing near the possible squishy kidney?”).

-          If a cow has feet problems, then a common way to examine them is to put them in a rotating table where they are on their side and their feet are easily assessable. Seriously!

-          No matter how hygienic I am, I am constantly worried I will get a zoonotic disease. Crypto, Brucella, Q fever, oh my!!

-          Blood draws from pigs commonly occur from the cranial vena cava and is a mostly blind stick. How. Terrifying.

-          An Alpaca’s young is called a cria, and alpacas giving birth is called criation (pronounced “creation” I kid you not!).

-          Taking a blood sample from a caudal tail vein is easier than one might think.

-          You really shouldn’t drink unpasteurized milk. There are SO many diseases you can get that pasteurization prevents.

-          Sheep and goats have rectangular pupils.

-          Some alpacas are freaking drama queens.

-          A lot of cow surgeries can be done with them standing up!

-          A real accomplishment of the day would be to not leave the hospital with rumen juice, alpaca spit, or poop on my coveralls/face.

shatterstag  asked:

Hi Scriptmedic, long time fan, first time writer! I have a gothic horror fantasy protagonist who's a surgeon in a Victorianish setting. The character gets into some necromantic shenanigans, and performs a ritual where he cuts out his own heart. He 'survives' the process by becoming undead/a ghost during it. How would I viscerally describe a surgeon doing this if there was no pain, no need to stop bleeding, no need to be delicate, yet keep the vibe of a surgeon operating on himself? Thanks! <3

Hey there @shatterstag ! Congrats on the first ask of October! This one is spooky enough for Halloween.

Here’s a special trick treat. Feel free to modify it, scorn it, or copy and paste it directly into your story.

Squeamish readers, skip this one. 

The mirror wasn’t strictly necessary. He was good enough to do it by feel if he had to. But the mirror added theatrics. Made it real. Made it a show, one only he could see.

He was so used to the operating theater: the rows of doctors murmuring in their seats as the surgery happened. But now it was just him.

He opened his shirt. Lay down a clean towel in his lap. The pain wouldn’t bother him. But the trousers were too nice to spoil.

He began with a cut down the breastbone. From the V at the hollow of his throat to the tip of the breastbone. A red trail preceded the tip of the scalpel as the wound oozed. The white shine of bone could be seen, underneath the skin and parting muscle.

Next were the pruning shears.

He had considered a saw, but it would have proven ineffective. He had used it on cadavers before, but the angle made it impossible.

Instead he began with the shears on either side of the sternum. The cartilage where the ribs spread off was thick and tough.

The first one gave with an awful thunk and a sound like a small branch snapping.

It was peculiar. It should have hurt. The snapping of the bone should have done more than made him grind his teeth from the sound. He should have felt agony. The only people this was done to were the dead, and they didn’t mind.

He smiled. Perhaps he was dead already.

He made his way from bottom to the top: tenth, ninth, eighth, all the way through the first. The snap snap snap of the ribs echoed in the empty theater.

The right side followed. This was more awkward: his left was not his strong hand, but he managed.

He pulled his breastbone off his chest like a flap.

What remained was a window into the workings of his organs. He could see his gray-purple lungs expand and collapse with his breath. His heart hung beating nestled between them.

Even as a doctor he had never seen a human heart beat. The science of medicine had not yet advanced to being able to cut a man’s chest open and have him live.

He reached out his fingers to touch it. He felt the chambers pump. It squeezed and released over and over. The very foundation of his pulse was at his command. 

He held the scalpel against the arch of the aorta, that main thoroughfare of blood from the heart to the body. He watched his own deep breath in the mirror. The hand that held the scalpel did not betray him. It was steady as a rock.

He sliced.

Blood sprayed as much as a yard from his heart. It splattered on the mirror and soaked the white towel in his lap red. He could feel it soak through and into his trousers in moments. It was warm. 

He knew he would not die as he watched the blood slow to a trickle. His heart began to quiver under his hand, and then was still.

Perhaps he was already dead. Or perhaps he was well beyond death, into the thing that lay just on the other side of a heartbeat.

He finished the incisions: pulmonary artery, pulmonary veins, vena cava high and low. His bare hand was slick with his own blood as he held his heart up to the light.

Morbidly he squeezed it: top for the atria, bottom for the ventricles. It dribbled a dark red trickle down his ruined shirtsleeve.

He stood, chest yawning open to the world.

He dropped his stone-dead heart on the floor. It hit with a wet thud. He thought he saw it quiver once and then go still. 

Then he stood, and put down the towel, and walked out of the theater.

He did not look back.

Anyway, that’s how I’d do it.

xoxo, Aunt Scripty

[disclaimer] – wait does fiction need a disclaimer?!