December 11, 2015
Written by Liana Fong (class of 2015-2016)
This morning, Dr. Harken started the morning meeting with a discussion about collateral ventilation. This lecture was more difficult for me to follow than the last time I attended. He started by asking the residents to describe SOB (shortness of breath) and how to measure maximal voluntary ventilation. When someone has shortness of breath, the individual breathes too fasts, which has him (or her) blowing off CO2. This results in vasoconstriction in the brain since CO2 is a potent vasodilator. Eventually the individual passes out. Dr. Harken mentioned the ventilation-perfusion (V/Q) ratio and how it’s like a bell curve. V/Q is the ratio of the amount of air getting into the alveoli to the amount of blood being sent to the alveoli. Having adequate ventilation but zero perfusion in the alveoli results in “dead space” while having a V/Q of zero results in a physiological shunt. He made an interesting comment about how someone post-lobectomy does not have SOB and has a V/Q = 1.
The one surgery I observed today was a left breast lumpectomy and sentinel node biopsy. Before beginning, a blue dye called isosulfan blue was injected in the area around the upper half of the patient’s left areola. This dye gets taken up by the lymphatic system and stains the sentinel nodes blue to allow the surgeons to visualize them for removal. Dr. Godfrey was the supervising surgeon and there were two residents who performed and assisted with the surgery. The initial incision seemed fairly small compared to the estimated size of the mass to be removed. There were many small strokes of the Bovie to cut through the fascia and adipose and cauterize blood vessels. I managed to get a good view of the surgery by standing on a stool by the anesthesiologists. When near the anesthesiologists, the anesthesiologist resident gave the patient more medication to prevent her from waking up. He noticed on his monitor that she was slowly starting to breathe on her own by the blue portions of the colored waves on the screen. The yellow wave on the bottom of his screen monitored the patient’s ventilation. I believe it was called a capnogram and measured the amount of CO2 in the patient’s exhaled breath; its waveform is supposed to look like uniform, square mesas with the CO2 levels being between 35-45 mmHg. When the physicians lifted the mass from inside the breast, I saw it was the size of a small lemon. It looked like an unremarkable lump of fatty tissue to my amateur eyes so I was amazed with how they determined whether or not they removed all of the abnormal mass just by looking at the surgical site. Once removing the mass, they inserted stitches to it to note how the mass was oriented when it was inside the body. They then sent the mass to radiology to get it imaged. Pieces of the area surrounding the mass were excised, labeled, and placed in formaldehyde for examination as well. With the mass being the size of a lemon, I was intrigued by the surgeons stitching up the breast incision without putting anything to fill the space left by the mass. I was told eventually that empty space will be filled in by the surrounding adipose. After completing the breast stitching, the surgeons made an incision in the axilla to remove a sentinel lymph node. The blue dye injected earlier was very faint so the lymph node was not very noticeable. It was excised with small strokes of the Bovie, had a stitch inserted for identification, and placed in a biohazard bag for biopsy. The whole procedure took about 3 hours. I was told to come watch the next surgery but I respectfully declined since I did not want to have to leave around when it would have begun. Before leaving, scrub tech Joe showed me the various surgical clamps, cutters, and tweezer-looking instruments that come with their surgical tool sets and briefly showed me where the dirty instruments go to be cleaned. Cleaning and sterilizing the tools requires multiple steps before being usable again.