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What pulmonary function tests would prohibit cardiac surgery

No absolute number but operative mortality much higher in those with COPD.

P02 < 60 on room air
pCO2 > 60
FEV1 < 65% VC
FEV1 < 1 to 1.5 L
DLCO < 50% predicted
Vo2 max > 10 cc/kg, the best predictor but rarely measured
failure to response to broncho dilators


What is mechanism of action of Heparin induced thrombocytopenia

IgG antibody binds to complex of platelet factor 4 and heparin leading to the formation of an immune complex.

The immune complex binds to platelets via platelet Fc receptors producing intravascular platelet activation, thrombocytopenia, and the potential complications


What are 3 types of HIT

Type 1: mild drop in plt count that stays > 100 000--management is to observe. repeat the count

Type II: moderate drop in < 100 000---without thrombosis. Treatment is to stop heparin, alternative anticoagulation and monitor for thrombus

Type III: HIT with evidence of thrombosis--mortality is about 30% and rate of amputation is 20%


What are alternatives to Heparin in a pt with HIT

* direct thrombin inhibitors
1) Argatroban (cleared by liver) short half-life

2) Liprudin (cleared by renal)

3) Danaparoid (cleared renal)

4) Ancrod


List predictors of increased low cardiac output syndrome

LVEF < 20%
redo operation
Emergency operation
Female gender
Left main
recent MI < 30 days
age > 70


What is definition of Low Cardiac output syndrome

SBP < 90 mmHg
CI < 2.2 L.min/m2
need for inotropes or IABP > 30 min in ICU


List 5 surgically correctable complications of acute MI

Ischemic ventricular septal defect (anterior or posterior)
Acute mitral regurgitation
ruptured papillary muscle
ruptured choradae
Left ventricular aneurysm
Ventricular freewall rupture
Cardiogenic shock from acute occlusion of one or more coronary arteries


What are complications of IABP

leg/limb ischemia
bleeding from puncture site
Occlusion of branch vessel
aortic rupture
aortic dissection
femoral neuropathy
lymph fistula


What is mechanism of IABP

Augments diastolic coronary perfusion
reduces after load

Effects on LV
decreases LV afterload during systole
decreased myocardial oxygen consumption
increased myocardial blood supply during diastole
Effects on ascending aorta
lower peak systolic pressure
peak aortic pressure is increased
end diastolic pressure is lower


What are some facts about IABP

augments CO by 10 to 25%
should inflate immediately after closure of dicrotic notch (AV closure)
deflation as late as possible (timed to onset of R wave)
Triggers off arterial wave or ECG
Balloon should occlude aorta during diastole (34 or 40 cc Balloons)


How do you diagnose a perioperative MI

The following new finding on ECG
Q wave (2 contiguous leads)
Loss of R wave progression
Presence of new ST-T changes and serum enzyme rise including one of
Trop > 10
CK-MB >50
Ck-MB ratio of > 5 %

The presence of perioperative MI must include the presence of ECG changes

New definition in the 2011 guidelines
Increased biomarker 5x upper limit with new Q wave or LBBB
Angiographic documentation
Imaging documentation of loss of viability in new territory


3 causes of diaphragm paresis post-op

Phrenic nerve injury secondary to
topical hypothermia
Damage during LITA harvest (proximal end of ITA
damage during pericardial incision
damage during retraction of chest wall
0.5% if no topical cooling
32% with slush...(wow!!!)
2-6% with topical saline


Possible causes of recurrent laryngeal nerve injury

Dissection and direct injury during arch procedures
Cold solution in left pleural space
Injury during central line placement

May take 8 - 12 months to recover.
If severe respiratory compromise may need reintubation and traceostomy
Consult ENT
medialize the vocal chord by teflon injection


What are complications from Swan

bleeding hemothorax
air embolism
carotid puncture
Related to presence in situ
venous thrombosis
ventricular arrhythmias
Branch PA rupture


What is management of swan rupture

Blood from ETT, opacity of lung near PA catheter tip, bronchoscopy

ABC, secure airway, large IV, fluid, reverse coagulation aggressivlely

protect good lung
patient with bleeding side down
broch blocker or double lumen ETT or selective intubation
angiography with embolization
risk of death is 30%


What are 6 most common general surgery issues post cardiac surgery

Upper GI bleeding
hollow visucus perforation
Mesenteric ischmia
Hepatic failure


8 most common post-op pulmonary complications

Pleural effusion
pulmonary edema
Diaphragmatic paralysis
Prolonged mechanical ventilation


What are two tests ordered for HIT


Serotonin release assay


What is dosing of argatroban for HIT



What are Classification of neurological deficits post op

Type I: major focal neurological deficit, stupor and coma
Type II: deterioration in intellectual function or memory


List predictors of type I

Proximal aortic atherosclerosis (4.5)
History of prior neurological disease (3.2)
Increasing age
unstable angina


Predictors of type II

prior CABG


Tests for HIT

Serotonin release test: measure release of radio-labeled serotonin from normal platelets washed with platelet serum. A test of platelet degradulation

ELISA: measures the levels of IgG-AB directed towards H-PF4 directly. More sensitive in those who otherwise do not have clinical evidence of disease


List indications for NO

Cardiac transplant pts
Lung transplant pts
pulmonary hypertension post valve surgery
Right ventricular failure
Lung transplantation
Acute PE
Pediatric cardiac surgery


List some of the toxic byproducts of Nitric Oxide

Nitrogen dioxide (No2)


List ways to decrease PVR

High FiO2
nitric oxide
*keep the PEEP low, avoid vasoconstrictors, keep warm, no acidosis!


What is Dexamedtomidine

Highly selectve alpha 2 adrenorecptor agonist and has anxiolytic, sympatholytic, and anlgesic effects without contributing to respiratory depression, oversedation, or delerium


What is rate of noscomial pneomnia

1% per day of VAP


What is risk of renal failure for cabg

2-4% of all patients


What are treatments of post operative seizer

Valproic acid (750mg)
Dilantin 15-20 mg/kg


Lorazepam 4 mg IV


What are sources/causes for elevated lactate post cardiac surgery

Anaerobic metabolism
Tissue hypoxia
response to B2 adrenergic receptors
and CPB increases lactate concentration and decreases lactate clearance


What is mixed venous sat and what is normal value

MVO sat represents the difference between oxygen delivery and oxygen consumption by the tissue and hence can be used as an indirect measure of cardiac outout

Normal is 60 to 80%


What are causes of low mixed venous sat

Decreased oxygen delivery: low cardiac output, anemia, reduced oxygen saturations

Increased oxygen consumption: secondary to hypertermia, pain and shivering


What causes for high venous saturations

decreased oxygen consumption or extraction, secondary to hypothermia, sepsis or shunting

increased oxygen delivery (raised inspired oxygen concentration

a wedged pulmonary artery catheter


List factors in weaning off ventilator

PO2 > 80mmHg w/ FiO2 ≤ 0.5
pH (on CPAP) ≥ 7.35
PCO2 ≤ 45mmHg
vital capacity (VC) ≥ 15mL/kg
negative inspiratory pressure ≥ 20cm H2O
Alert, awake
absence of bleeding, HD instability or dangerous arrhythmia


What is order of injured chambers in a cardiac trauma

RV (35%), LV (25%), RA (24%), and LA (3%) form the order of the most common to the least common injured chambers, respectively.



How does a PA cath measure cardiac output

“thermodilution is used to determine CO. A cold saline bolus is injected into the catheter to measure change in blood temperature as a function of time; this indicates the rate of blood flow. The area under the time-temperature difference curve is measured to determine the CO. A low area under the time-temperature difference curve indicates high CO.”



How does vasopressin work

stimulates V1a receptors in vascular smooth muscle, which results in vasoconstriction.

mediates fluid reabsorption by stimulating V2 receptors in the renal collecting duct system. Based on the level of stimulation, the renal collecting ducts can become either more permeable or less permeable to fluid.”


What's acute lung injury .

“the presence of bilateral infiltrates, and pulmonary capillary wedge pressure < 18 mmHg. degree of hypoxemia distinguishes ALI (PaO2/FiO2 < 300) from ARDS (PaO2/FiO2 < 200).

PaO2/FiO2 ratio is a reflection of the shunt fraction through the lung and is a barometer of gas exchange. ratio < 300 as in ALI, there is increased mortality, and in ARDS with ratios < 200, there is a predicted mortality of 40% to 50%.”


What is treatment ARDS

“Mechanical ventilation using the least FiO2 necessary (goal < 60%), low tidal volume settings (6-8 mL/kg) with peak inspiratory pressure (PIP) < 35 cmH2O, the use of PEEP between 8 and 14 cmH2O
Cardiovascular support with a goal oxygen delivery/consumption > 2:1, hemoglobin > 10 mg/dL, and inotropic support
Nutrition support with adequate nitrogen balance and preference for enteral feeding
further maneuvers include permissive hypercapnea, diuresis, prone positioning, late steroids, ECMO”


What pulsus paradox

pulsus paradoxus, an exaggerated decrease of the systolic blood pressure with inspiration.

Ordinarily, bp decreases up to 10mmHg with inspiration in a spontaneously breathing patient.

In pulsus paradoxus, this decrease in systolic blood pressure is >20 mmHg without a corresponding decrease in diastolic blood pressure (see figure).


What is post op pericardiectomy

Syndrome is characterized by malaise, fever, pleuritic chest pain, pericardial effusion and leukocytosis.
friction rub may be present on examination.
Symptoms usually appear 1-2 weeks after cardiac surgery and may last several weeks. The syndrome is usually self-limited.
Most patients respond to non-steroidal anti-inflammatory agents and in some cases steroids are required


Why is ITA better then SVG

Anatomic properties include absent or very thin vaso vasorum, a dense internal elastic lamina with no fenestrations, and a thin medial layer with few smooth muscle cells.
secretes endothelial derived relaxing factors (prostacyclin and nitric oxide) that cause vasodilatation and antagonize endogenous endothilin and calcitonin, which are vasoconstrictors.
smooth muscle cells exhibit very little proliferation in response to platelet derived growth factor, as compared to saphenous vein.
exhibits flow adaptation over time


What are post op concerns of OHT coronary disease

incidence of transplant coronary artery disease is approximately 10% per year following transplantation.
angina and chest pain rare in the denervated heart the diagnosis is usually made by surveillance coronary artery angiogram or angiographic assessment following ECG changes, deterioration in functional status or cardiac function anomalies on echocardiogram.


What are risk of nerve damage with arch surgery

Left recurrent nerve injuries occur in approximately 10% of cases and are usually due to nerve contusion or a traction injury rather than actual nerve transection.
patients will be hoarse and will have difficulty generating a forceful cough.
The risk of aspiration is substantial.
common in descending or thoracoabdominal aneurysm repair where control of the aorta is obtained proximal to the left subclavian artery.


What is advantage of percutaneous trach

By an experienced operator is equivalent to conventional open technique.
Ssimilar effectiveness of gas exchange and with similar long-term success at weaning from the ventilator.
PDT adoption is driven by considerations of convenience and cost. One study suggested an overall cost savings of approximately $30,000 per patient if percutaneous tracheostomy was globally adapted on a cardiothoracic surgery service.


Who are not good candidates for a percent trach

obese necks, thyromegaly, irradiation-induced changes, or other pathology that precludes palpation of the cricoid and tracheal rings are not good candidates for PDT.


List signs of constructive pericarditis

findings consistent with constrictive pericarditis include paradoxical rise in venous pressure with inspiration (Kussmaul's sign)

A steep or exaggerated y descentindicates rapid atrial emptying with rather abrupt cut-off of ventricular filling and rapid rise in the venous pulse trace after the initial drop during diastole. The steep y descent is typical of constrictive pericarditis whereas the y descent is attenuated in tamponade.


What are additional signs that distinguish cp from rp

right and left ventricular pressures are equalized and there is a "dip & plateau" configuration in the diastolic phase of the ventricular pressure tracing.
This square-root sign" and is caused by rapid early diastolic filling followed by limited ventricular filling due to maximal ventricular wall distension allowed by the pericardium.

Limitation of ventricular filling is seen in both cardiac tamponade and constrictive pericarditis.


What is vasoplegia and dose of methylene blue

Vasoplegic syndrome was defined by the presence of the following five criteria: (1) hypotension, (2) low filling pressures, (3) high or normal cardiac index, (4) low peripheral resistance, and (5) vasopressor requirements

1.5 mg/Kg of methylene


What are predictors for vasoplegia syndrome and rate

Occurs in 5 to 8 %

Ace inhibitors


Who does ACE cause Vasoplegia

Increase in Bradykinin levels leads to endothelial dilation

mortality of VS can be as high 25%


What is role of Nitric oxide in Vasoplegia

NO is a mediator in the systemic inflammatory response.
NO stimulate guanylate cyclase enzyme activation and cAMP production which causes smooth vascular muscle relaxation.


How does Methylene blue work

MB is a guanylate cyclase inhibitor

Competitively inhibits NO, in binding to the Iron Hem0 of cGAMP.

This counteraction the effects of NO and other nitrovasodilators in endothelium and vascular smooth muscle.


List side effects of MB

1) Urine blue for about 5 days
2) Falsely low readings on pulse oximetry
3) changes in alveolar gas exchange
4) possible N/V/abdominal discomfort


What are rates of Gross Neurologic system dysfunction

0.5% in young patients
5% in pts over 65
8% in pts older 75

mortality rates are 20%
5% chance of recovery if absence of pupillary light reflex, corneal reflex, caloric relfex, or dolls's eyes


What are rates of cognitive impairment post cardiac surgery

60% have normal cognitive function at 8 weeks after surgery

80% are normal at 6 months to 5 years


What are rates of renal injury

associated mortality of 50%

post op renaly dysfunction (doubling or greater of creatinine occurs in 1%) if preop function normal


What are rates of mortality with GI complications

30 to 50%

5 % develop severe pancreatitis
20% elevated bilirubin


What are rates of bleeding

re-exploration 3 to 5%
> 500/hr x 1
> 400/hr x 2
> 300/hr x 3
> 1000 total in 4 hours


What is most common organ of dysfunction post cardiac surgery

absence of pulmonary flow results in low sheer stress and accentuates neutrophil activation


What are principles of management of patients in right heart failure

Optimise right ventricular preload
atrioventricular sequential pacing
restore sinus rhythm
Optimise right ventricular contractility
phosphodiesterase inhibitor/prostacycline/
Optimise right ventricular afterload
correct hypoxia, hyercarbia, and acidosis
Inhaled nitric oxide (20-40 ppm)
Right ventricular assist device
nesiritide (recombinant brain natriuretic peptide

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