Cardiac Surgery, Post-Operative Care, and Hemodynamic Monitoring

Flashcards covering vocabulary, physiological concepts, pharmacological agents, and hemodynamic parameters related to coronary artery bypass grafting (CABG) and open heart surgery.

Dual Antiplatelet Therapy (DAPT)

A drug regimen consisting of aspirin combined with a P2Y12 inhibitor such as clopidogrel or ticagrelor, routinely administered post-MI or after stent placement, which necessitates delaying elective surgery due to high bleeding risk.

Clopidogrel Loading Dose

A $300\,\text{mg}$ loading dose administered initially (followed by a standard maintenance dose of $75\,\text{mg}$ daily) that prevents platelet aggregation, preventing immediate surgical intervention until it clears from the system.

Pre-operative Beta Blockers

Medications that must be continued the day of cardiac surgery to avoid sudden withdrawal, decrease heart workload and oxygen demand via decreased contractility, and decrease the risk of post-operative atrial fibrillation.

Minimum Target Potassium Level

A minimum laboratory value of $4\,\text{mEq/L}$ maintained in post-cardiac surgery patients to prevent hypokalemia-induced dysrhythmias.

Minimum Target Magnesium Level

A minimum target electrolyte level of $2\,\text{mg/dL}$ required for post-operative cardiac patients to optimize rhythm stability.

Prophylactic Surgical Antibiotics

An intravenous antimicrobial regimen, such as $2\,\text{g}$ of Ancef given $20\text{--}30\,\text{minutes}$ prior to incision followed by only two post-operative doses, intended to prevent surgical site infections without causing bacterial resistance.

Left Internal Mammary Artery (LIMA)

A graft vessel of choice that naturally branches toward the left anterior descending (LAD) artery, possessing sufficient length to reach from the aorta to perfuse the area normally supplied by the LAD.

Saphenous Vein Graft

An autologous venous graft harvested from the leg through incisions in the upper thigh and behind the knee, frequently causing post-operative leg pain and temporary impairment of venous drainage.

Anastomosis

The delicate surgical connection joining a graft vessel to a native coronary artery, susceptible to rupture or blowing out if systolic blood pressure exceeds $130\,\text{mmHg}$.

Sternal Splinting (Bracing)

A technique taught to patients using a heart pillow or their hands held firmly against the sternal incision to reduce pain and prevent incision dehiscence when coughing or deep breathing.

Extubation Window

The standard targeted post-operative timeframe of $3\text{--}6\,\text{hours}$ during which a cardiac surgery patient should be weaned from mechanical ventilation and extubated once hemodynamically stable and following commands.

Suction Control Chamber (Wet Chest Drainage)

The compartment of a chest drainage unit filled to $-20\,\text{cm H}_2\text{O}$ that exhibits continuous bubbling when suction is appropriately connected and functioning.

Water Seal Chamber

A chest drain chamber filled with $2\,\text{cm}$ of water designed to allow air to exit the pleural space while preventing atmospheric air from re-entering, characterized by tidaling with respirations and absence of continuous bubbling unless an air leak is present.

Tidaling

The expected, normal fluctuation of the water level in the water seal chamber reflecting changes in intrathoracic pressure during inspiration and expiration.

Mediastinal Chest Tubes

Tubes placed directly within the mediastinal space following sternotomy to drain accumulating blood and prevent pericardial fluid accumulation or cardiac tamponade.

Chest Tube Stripping

A bedside nursing technique utilizing lotion on hands to squeeze along the drainage tubing toward the collection chamber to generate negative pressure, clearing clots and maintaining tube patency.

Epicardial Pacing Wires

Temporary pacing wires attached directly to the epicardium during surgery, routed externally to allow connection to an external generator in the event of post-operative conduction blocks or dysrhythmias.

Atrial Kick

The final squeeze of atrial contraction during diastole that contributes roughly $10\text{--}20\%$ of cardiac output and blood pressure, which is lost when pacing solely with ventricular wires.

Pulmonary Artery Catheter (Swan-Ganz Catheter)

An invasive catheter floated through the right atrium and right ventricle into the pulmonary artery to measure intracardiac pressures, cardiac index, and mixed venous oxygen saturation.

Right Ventricle Waveform

The distinct hemodynamic waveform observed on the monitor as the pulmonary artery catheter passes through the right ventricle, characteristically resembling ventricular tachycardia.

Pulmonary Capillary Wedge Pressure (PCWP)

An indirect measurement of left atrial and left ventricular end-diastolic pressure, obtained by briefly inflating the catheter balloon in a pulmonary artery branch, with a normal range of $8\text{--}12\,\text{mmHg}$.

Pulmonary Necrosis / Infarction

A severe complication caused by leaving a pulmonary artery catheter balloon continuously wedged, blocking blood flow to downstream pulmonary tissues.

Mixed Venous Oxygen Saturation ($\text{SvO}_2$)

The percentage of oxygen bound to hemoglobin in blood sampled directly from the pulmonary artery, normally ranging from $60\text{--}80\%$, reflecting the balance between oxygen supply and systemic tissue consumption.

Systemic Vascular Resistance (SVR)

The resistance against which the left ventricle must pump to eject blood; elevated post-operatively due to compensatory vasoconstriction and lowered therapeutically with vasodilators like nitroglycerin or milrinone.

Dicrotic Notch

A distinct downward deflection seen on an arterial line waveform that represents the closure of the aortic and pulmonic semilunar valves.

Phlebostatic Axis

The anatomical external reference point situated at the 4th intercostal space, midclavicular/mid-axillary level corresponding to the level of the right atrium, used to zero invasive pressure transducers.

Cardiac Tamponade

A life-threatening complication resulting from blood or fluid accumulation compressing the heart, manifested clinically by muffled heart sounds, a widened mediastinum on chest X-ray, and pulsus paradoxus.

Pulsus Paradoxus

An abnormal drop in systolic blood pressure of approximately $10\,\text{mmHg}$ or greater during spontaneous inspiration, indicating potential cardiac tamponade.