Cardiac I Flashcards

Question

How do we provide prophylaxis for bleeding?

Answer 1

* Prophylactic use of **antifibrinolytic** drugs **_before_** CPB * **reduces bleeding and transfusion** * Drugs include: * Synthetic lysine analogues * ε-aminocaproic acid (**EACA**) – Amicar * Transexamic acid (**TXA**) * Serine protease inhibitor = Aprotinin * Taken off the market dt significant tissue organ damage * Being researched again in Canada * *Amicar bolus and infusion PRE pump to reduce bleeding and need for transfusion*

Answer 2

Risks: * Embolization * Hypoperfusion * Bypass machine at low pressures/flow * Inflammation from pulsatile to flow BP **Influencing Factors/predisposition: (people at risk)** * Aortic atheromatous plaque (atherosclerosis in aorta) * Cerebrovascular disease * Altered cerebral autoregulation (elderly) * HoTN * Intracardiac debris * Plagues * Air * Cerebral venous obstruction on bypass * Cardiopulmonary bypass circuit surface and damaged blood cells * Reinfusion of unprocessed shed blood (cell saver) * Cerebral hyperthermia (rewarmed too quickly) * Hypoxia (serial ABGs)

Answer 3

* **Emboli** are biggest culprits * **PROTECTION:** * Hypothermia → decrease CMRO2 * Barbiturate therapy? * Used to give TPL/Methohexital decrease BF to brain * CCBs * increase perfusion to brain * Blood gas management * Draw from aline * Adequate BP (run machine at good flows) * blood cell damage vs. CPP? Individualized * (look at risk list above and those prob need higher pressures) * Cerebral oximetry

Answer 4

* **Minimize crystalloids –** hemodilutes pt * **1-1.5 L acceptable for crystalloids** * Replace blood w/: * Colloids * Cell saver * PRBCs

Answer 5

* Begins at different times: (Surgeon can ask for rewarming of pt) * 1. Begins **prior** to **aortic** **cross-clamp** **removal (or)** * *2.* Begins with the **last distal anastomosis** in angioplasty procedure (or) * *3.* Begins when **all the valve sutures** are in and **knots** are being tied down * **Considerations:** * **1° C per 3-5 mins (slowly)** * Usually takes ~ 30-40 mins * Turn on heating blanket * Temp gradient bt _arterial_ and _venous_ blood should remain _\< 5-10°C_ * if gradient higher → **higher risk of air emboli** * Amnestic and NMB agents should be given (recall) * SVR drops d/t vasodilation * Monitor pressure\* * Phenylephrine can be given to perfusionist since they have more direct access

Answer 6

* Pt must be _warmed_ * Surgical field should be _dry (_no bleeding) * _Lab values_ checked * Admin Ca & Mag to decrease effects of cardioplegic soln (high K) * _Pulmonary compliance_ evaluated * Begin ventilating lungs slowly **(attach circuit)** * Manually bag pt to see compliance → watch lungs * Then switch to ventilator * Regulate cardiac rhythm by pacing, defibrillating or pharmacologically * Ca, Mg * Transfuse pt with _pump volume (~50-100cc by perfusionist)_ * Look at: * PA Diastolic pressure * TEE\* * Actual heart over drapes (floppy?) * VS

Answer 7

* “CVP” * Cells- PRBCs * Vaporizers- turn on gas since perfusionist turns off theirs * Volume expanders- for HoTN * Predictors: * Based off preop assessment * Arrythmias beforehand? * Potassium/Mag/Calcium balance * Protamine- AFTER everything else looks good (last thing)

Answer 8

* Use the ratio of **systemic BP to pulm BP** * **EXAMPLES**: * **If pulm pressure ↑, but BP ↓** = **ventricular failure** **(inotropic agent)** * PA pressure high → diastolic fx not working properly and BP low → SV or stroke pressure poor → ventricle not fx properly * **Tx: Inotropic agent**→ increase force of contraction * **If CO is low, but BP is adequate** = **SVR high (overly vasoconstricted)** * BP good but heart cant pump against heavy constriction * **Tx: vasodilation** * **If BP is low:** * Inotropes * volume (cell saver, PRBC, whole blood) * Diagnose THEN treat * Look at BP and PA pressures * Once the pt is stable, bypass is completely d/c’d

Answer 9

Assess function **LV support =** * Inotropes * PRBC * Preload * afterload **RV support =** (need to ↓ pulm vasoconstriction) * Nitric oxide-based vasodilators * β₂ agonists * prostaglandin E₁ * **RV failing unrelated to pulm vasoconstriction**: * cyclic adenosine monophosphate-specific phosphodiesterase inhibitors * (Phosphodiesterase inhibitors are a class of medications that **promote blood vessel dilation** (vasodilation) and smooth muscle relaxation in certain parts of the body, such as the heart, lungs, and genitals) * If not working: * IABP (intra-arterial balloon pump) * Ventricular Assist Devices

Answer 10

**Step 1:** HR \< 70 (conduction block) * Pace * Atropine * Isopril HR \> 100 * Balance Mg/K * Cardiovert * Amiodarone **Preload optimization →** High Preload: * stop filling * head up tilt (reduce blood coming back to heart) * diuretics MAP \> 90 * vasodilators (NTG, NPS) Once all criteria met → then can successfully come off bypass and remove arterial cannula and TE THEN give protamine. (ACT come back to normal) **Step 2: (if not able to wean)** * Ventricular failure * Tx: inotropes, blood back from pump, inhaled NO, etc * If successful, ok to come off arterial cannula and TEE→ then give protamine and ACT check If not successful → balloon pump or VAD to leave

Answer 11

Example: * BP and VFP high * CO low * Dx: high vasoconstriction (or) * Low contractility * Tx: Inotrope or vasodilation Example: * BP down * Filling pressures down * SV up * Dx: DECREASE SVR * Tx: Vasoconstrictor

Answer 12

* Derived from salmon sperm * Pts w/ vasectomies (develop AB against sperm) → Allergic Rx to protamine * **Dose:** * **2-4 mg/kg** * **1-1.3 mg per 100units of Heparin given** * Administration considerations: * SLOWLY push (over 5-10 min) * \*Massive vasodilation/drop in BP\* * CVP line (draw back and ensure good line) * Check ACT and give more accordingly * ~ \< 100

Answer 13

* **Anaphylaxis can occur:** **Admin w/ premedication or alternatives to heparin** * Pts with previous exposure * Pts with vasectomy * Pts on NPH (Neutral **Protamine** Hagedorn) (prior exposure technically) * Can cause vasodilation, give slowly over \>5mins. * Pts with documented _adverse events_ related to protamine → **do not rechallenge** with protamine * Pharmacologic _alternatives_ to protamine: * Do not reverse heparin * Non–heparin-based CPB * Performing off-pump coronary artery bypass (OPCAB) with an alternative to heparin * Surgeon dependent (variable) * **Non-protamine heparin reversal drugs:** (if heparin used) * **PF4** * **Heparinase** * **MOA:** deactivates heparin (not technically reversing it) * Simply _waiting_ for heparin’s effects to dissipate

Answer 14

**Post Bypass** * Transfusion * Coagulation * Stability of VS * _Drop in BP with chest closure \*_ * Maintain inotropes, NTG, NTP, etc. * Continue vigilant watch **Post op** * Travel to ICU/CCU with monitors & + O₂ * Bring backs * 4-10% * usually d/t **bleeding →** less common now w/ TEE * **Cardiac tamponade** * Post op pain control * Sternotomy very painful! * Ex: Fentanyl drip, morphine, dilaudid, etc

Answer 15

* Numerous approaches * Techniques vary amongst sites and surgeons * **Good practice:** * **↓ HR and ↑ preload** * Surgeon handling heart → good way to maintain BP * Avoid and tx arrhythmias * Handing might cause arrythmias * Adjust ventilator settings * Ex: small TV, higher RR, add PEEP * Heparin available in case pt has to go on bypass * Reversal of heparin depends on the institution

Cardiac I Flashcards

(39 cards)