Principles of Postoperative ICU Management: Part 1

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Principles of Postoperative ICU Management Part
1

• Allison K. Cabalka, MD
• Associate Professor of Pediatrics
• Consultant, Pediatric Cardiology
• Mayo Clinic

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Objectives

1. Describe basic hemodynamic monitoring and
   evaluation of the postop CHD patient
2. Review common vasoactive medications used in the
   ICU
3. Briefly discuss postoperative arrhythmias and
   treatment

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Objectives

1. Describe basic hemodynamic monitoring and
   evaluation of the postop CHD patient
2. Review common vasoactive medications used in the
   ICU
3. Briefly discuss postoperative arrhythmias and
   treatment

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Basic Assessment

• Know preoperative anatomy
• Were there any important preoperative
  co-morbidities?
• Airway, GI, nutritional, neurological, etc.
• Review detailed surgical notes
• Was this palliative or complete repair?
• Expected status?
• Any important intraoperative events?

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Physical Exam

• General appearance?
• Overall color, quick assessment
• Use your hands!
• Cardiac output? Are the toes warm?
• Peripheral vs. central pulses, perfusion
• Hepatomegaly, ascites, edema
• Get out your stethescope!
• Any concerning lung sounds, murmurs, gallops

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Hemodynamic Monitoring

• Invasive lines
• Arterial blood pressure
• Central venous pressure
• Ventilator
• Peak/mean airway pressures/PEEP
• Oxygen saturation pulse oximetry
• What goes in vs. what comes out?
• Fluids and medications in
• Urine and chest tube output

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Bedside Monitor Basics
PGE1-dependent neonate awaiting neonatal surgery
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Bedside Monitor Basics
Heart Rate Rhythm
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Bedside Monitor Basics
BP
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Bedside Monitor Basics
CVP
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Bedside Monitor Basics
Pulse Oximeter
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Bedside Monitor Basics
RESP
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Postop Hypotension?

• 3 Main Causes
• Low intravascular volume (hypovolemia)
• Inadequate filling pressure, blood loss
• Low cardiac index
• Poor pump function
• Maldistribution of intravascular volume
• Vasodilation with poor peripheral vascular tone
• Usually normal cardiac function

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Volume Status?
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CVP

• Used to assess right ventricular function and
  systemic fluid status
• Normal CVP is 2-6 mm Hg
• CVP is elevated by
• Overhydration - increases venous return
• Heart failure or stiff RV which limit venous
  inflow and leads to venous congestion
• Positive pressure ventilation
• CVP decreases with
• Hypovolemia, shock from hemorrhage, fluid shifts,
  and low intravascular volume/dehydration

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Assessment of Volume Status

• Some postop conditions require higher filling
  pressures to maintain cardiac output
• Postop TOF with stiff, hypertrophied right
  ventricle
• Fontan or single ventricle patient
• Consequences of sustained high CVP?
• Ascites, liver congestion, effusions
  (chylothorax)

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Volume Resuscitation

• Basic colloid or crystalloid solution
• 5 Albumin, Normal saline/LR
• Be sure that Hgb is high enough for clinical
  situation
• Cyanotic patients typically require a higher Hgb
• O2 carrying capacity depends on Hgb
• Remember equation for cardiac output (systemic
  index)

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PRBC Transfusion?

• Recent studies suggest adverse effects in adults
  undergoing heart surgery
• Is it associated with prolonged duration of
  mechanical ventilation in neonates?
• Recent publication from Boston Childrens
• Neonates undergoing 2-ventricle repair
• Multivariate analysis strongest predictors of
  DMV were total support time, greater
  intraoperative blood use early postop blood use

Kipps AK, et.al., Ped Crit Care Med, 2011
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Objectives

1. Describe basic hemodynamic monitoring and
   evaluation of the postop CHD patient
2. Review common vasoactive medications used in the
   ICU
3. Briefly discuss postoperative arrhythmias and
   treatment

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So Youve Done Your Volume Resuscitation

• CVP appropriate or high
• Hgb appropriate (but not too high)
• BP is still not what youd like
• UOP is still not what youd like
• Time for vasoactive agents
• And perhaps an echocardiogram

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Basic ICU Medications

• Most medications used in the fresh postop CHD pt
  are vasoactive
• That is, manipulating vascular bed in some way or
  another
• Inotropic medications
• Afterload reduction
• Pulmonary vasodilators

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Basics of Receptors

• Alpha adrenergic
• Alpha-1 receptors located in vessel walls,
  activation induces significant vasoconstriction
• Beta adrenergic 
• Beta-1 receptors most common in the heart,
  stimulation increases inotropy and chronotropy
  with minimal vasoconstriction
• Stimulation of Beta-2 adrenergic receptors in
  blood vessels induces vasodilation
• Dopamine
• Renal, splanchnic (mesenteric), coronary, and
  cerebral vascular beds
• Stimulation of these receptors leads to
  vasodilation

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Inotropic Drugs
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Dobutamine

• Primarily acts on beta1 receptors, with some
  beta2 and alpha effect
• Increase in cardiac index secondary to increased
  stroke volume
• Occurs without a significant increase in heart
  rate
• Less arrhythmia than epinephrine or isoproterenol
• SVR is either unchanged or decreased (at higher
  dose)
• No effect on pulmonary vascular resistance

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Dobutamine Indications

• Depressed LV function and elevated LV filling
  pressures (without significant hypotension)
• Desire for afterload reduction inotropy
• Dosing 2-20 mcg/kg/min titrated to effect
• Higher doses required in young children compared
  to adults

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Dopamine

• Sympathomimetic amine
• Direct stimulation of beta1 and alpha1 receptors
• Precursor of norepinephrine and epinephrine
• Indications
• Low cardiac output after cardiac surgery
• Septic shock
• Premature infants with hypotension
• Dosing range 2-20 mcg/kg/min

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Dopamine Side Effects

• Extravasation
• Tissue necrosis and gangrene
• Central venous infusion preferable
• Arrhythmia
• Supraventricular tachyarrhythmias
• Risk factors
• Preexisting supraventricular rhythm
• High dose dopamine (10-20mcg/kg/min)
• Increased PVCs at gt5mcg/kg/min

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Epinephrine

• Low/medium dose (lt0.08 mcg/kg/min)
• Mixed beta1 and beta2 agonist
• Inotrope and chronotropic
• Decreases PVR and increases PBF
• May result in V/Q mismatch
• High dose
• Alpha agonist
• Vasoconstrictor
• Increases PVR
• Likely reduces renal and mesenteric blood flow

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Epinephrine

• Indications
• Depressed ventricular function
• Low cardiac output
• Systemic hypotension
• Side effects
• Ventricular arrhythmia
• Hypokalemia
• Hyperglycemia
• Central venous access is required

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Epinephrine and Cardiac Arrest

• Drug of choice in CPR
• Given as a bolus in doses that stimulate
  alpha-adrenergic receptors (0.01 mg/kg 0.1
  cc/kg of 110,000)
• Repeated q 3-5 minutes during resuscitation
• No longer a role for high dose Epi
• No better outcomes (may be worse)

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Milrinone

• Phosphodiesterase inhibitor
• Inhibits cyclic nucleotide phosphodiesterase(III)
• Increases cAMP in myocardial and vascular muscle
• Increased cAMP increased intracellular calcium
  concentration
• Increased intracellular calcium
• Improves myocardial contractility
• Relaxes systemic vasculature

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Milrinone

• Indications
• Low cardiac output S/P surgery
• Dilated cardiomyopathy
• Sepsis associated cardiac dysfunction
• Effects
• Increases cardiac index
• Increases heart rate
• Decreases PVR and SVR
• Improves diastolic relaxation
• Dosage 0.25-1.0 mcg/kg/min
• Load on pump 50 mcg/kg

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What About Vasodilation?
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Vasodilators Basic Principles

• Work ? P x V
• ?P-pressure
• V-Volume that the heart pumps
• Decreased blood pressure decreased work
• Afterload Pressure

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Nitroprusside

• Direct smooth muscle relaxation
• Venous and arteriolar relaxation
• Decreased afterload
• Decreased preload
• Decreases SVR and PVR

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Nitroprusside

• Ventricular dysfunction
• Afterload reduction after cardiac surgery
• Low cardiac output syndrome
• Hypertensive emergencies
• Blood pressure control S/P coarctation
• Dosing Range 0.5-8 mcg/kg/min
• May be delivered in peripheral vein

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What About Vasoconstriction?
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Norepinephrine

• Endogenous catecholamine that acts at sympathetic
  postganglionic fibers
• Potent beta1 and alpha stimulator
• Minor beta2 effects
• Clinical Effects
• Increased cardiac index
• Increased systemic and pulmonary vascular
  resistance
• Dosage 0.05-0.1 mcg/kg/min (max 1-2 mcg/k/min)

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Norepinephrine Indications

• Vasodilatory shock (warm)
• Hyperdynamic septic shock
• Augments coronary blood flow by increasing
  systemic diastolic pressure
• Remember the effect of increasing afterload!
• Central venous access required

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Objectives

1. Describe basic hemodynamic monitoring and
   evaluation of the postop CHD patient
2. Review common vasoactive medications used in the
   ICU
3. Briefly discuss postoperative arrhythmias and
   treatment

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Background

• Existing data reports 27 to 48 incidence of
  arrhythmias in pediatric post-operative patients
• Effects of cardiopulmonary bypass/surgery
• Catecholamine stimulation
• Suture lines/patches/scarring
• Residual hemodynamic issues

Valsangiacoma E, Schmid ER, Schupbach RW et al
Ann Thorac Surg 2002 Pfammatter JP, Bachmann
DCG, Bendict PW, et al Pediatr Crit Care Med 2001
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Pediatric Postop Arrhythmia
28/189 (15) pediatric patients experienced an
arrhythmia
Arrhythmia


Junctional ectopic tachycardia (JET) 16 8.5
Complete atrioventricular block (CAVB) 7 3.7
Ventricular tachycardia (VT) 4 2.1
Reentrant supraventricular tachycardia (SVT) 1 0.5
Correlated with length of bypass time and
crossclamp time
Delaney J et al, J Thor Cardiovasc Surg 2006
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Sinus Tachycardia is the most common tachycardia
in children
Tachycardia
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Sinus Tachycardia

• Evaluation once rhythm is confirmed
• Hypovolemia
• Anemia
• Epinephrine
• Afterload reducing agents with low intravascular
  volume
• Remember fever and pain contribute
• Evaluate response to treatment
• Rate should NOT remain fixed

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Premature Beats

• Usually in isolation, PAC or PVC (some PJC)
• Not clinically significant
• Atrial irritability is common (check lines?)
• Surgical manipulation also contributes

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Postoperative SVT

• Automatic focus tachycardia
• Atrial ectopic tachycardia
• Junctional ectopic tachycardia
• AV Node dependent re-entry tachycardia
• Supraventricular tachycardia
• Concealed bypass tract, WPW, AVNRT
• AV Node independent re-entry tachycardia
• Atrial flutter
• Atrial fibrillation

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Automatic Focus
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Junctional Ectopic Tachycardia

• Common post-operative arrhythmia
• Originates from AV node
• Particularly in postop TOF/Fontan patient
• Heart rates gt150 beats per minute
• Loss of AV synchrony
• Look for AV dissociation
• Slower P wave rate
• Easy to diagnose with pacing wires postop

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Junctional Ectopic Tachycardia
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Junctional Ectopic Tachycardia

• Treat with IV Amiodarone
• Load 5-10 mg/kg IV
• Drip infusion of total of 10-20 mg/kg/24 hrs
• Alternative or complimentary
• Cooling (blanket, cooled NG lavage)
• Reduction of sympathetic stimulation
  (Epinephrine)
• Correct Ca and Mg levels
• Volume replacement
• Muscle relaxation

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AV Node Re-Entry
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Supraventricular Tachycardia
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SVT ECG
Treatment Intravenous Adenosine Rapid IV
Push Dose 0.1 mg/kg
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Pre-excitation (WPW)
This patient is at risk for postoperative SVT!
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Recurrent SVT Rx options

• Adenosine may be repeated but if SVT recurs
• Procainamide IV
• 15 mg/kg IV load over 30 min
• 20-80 mcg/k/min IV drip
• Beta-blocker therapy
• Propranolol
• Esmolol

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Propranolol

• ß-blockade atrial or ventricular arrhythmias
• Recommended IV dose
• 0.01 to 0.1 mg/kg (max 1 mg in infants and 3 mg
  in children)
• Given by slow infusion over 10 minutes
• Recommended PO dose
• 0.5 to 1 mg/kg/d in divided doses q 6 to 8
• Usual PO dose is 2 to 4 mg/kg/day
• Maximum recommended dose is 16 mg/kg/day or 60
  mg/day

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AV Node Independent
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AV Node Independent Re-Entry

• Atrial fibrillation
• Irregularly irregular
• No organized atrial contractility
• Atrial flutter
• Regular atrial rate, variable conduction
• These are extremely common in the postop adult
  congenital heart patient!
• Especially Atrial Fibrillation

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Management of Afib/Aflutter

• Clinically unstable Cardioversion
• Optimization of heart rate
• Negative chronotropic agents to slow HR via
  effect on AV node
• Beta-blocker
• Metoprolol (IV bolus of 2.5 to 5.0 mg over two
  min repeat q5min up to 15 mg total
• Esmolol (bolus 0.5 mg/kg over 1min followed by
  50 µg/kg/min, repeat 0.5 mg/kg and increase drip
  to 100 ug/kg/min

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Long-term AFib/Flutter

• Optimally perform cardioversion to convert to
  sinus rhythm
• Long-term rate control for Afib with Beta-blocker
  agents
• Atenolol, Metoprolol, Nadolol
• If remains in Afib, must anti-coagulate

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Sinus Tachycardia???
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Atrial Flutter 21
2 P-waves for every 1 QRS
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AFlutter Unstable
Cardiovert
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Postoperative Rhythm Issues

• Arrhythmias are common in the postop period
• Depending on the hemodynamic status of the
  patient, may be life-threatening
• Junctional ectopic tachycardia is the most common
  rhythm issue
• Amiodarone is useful for treatment of a
  broad-spectrum of arrhythmias
• AV Block seen with surgery near the AV node
• It may resolvebe patient!

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Conclusion

• Use all your tools to evaluate the
  postoperative CHD patient
• Use common sense!
• Use teamwork!

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