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Principles of Postoperative
ICU Management:
Part 1
Allison K. Cabalka, MD
Associate Professor of Pediatrics
Consultant, Pediatric Cardiology
Mayo Clinic
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
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
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?
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
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
Bedside Monitor: Basics
PGE1-dependent neonate awaiting neonatal surgery…
Bedside Monitor: Basics
Heart
Rate &
Rhythm
Bedside Monitor: Basics
BP
Bedside Monitor: Basics
CVP
Bedside Monitor: Basics
Pulse
Oximeter
Bedside Monitor: Basics
RESP
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
Volume Status?
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
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)
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)
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 Children’s
– 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
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
So You’ve Done Your Volume
Resuscitation…
•
•
•
•
CVP appropriate or high
Hgb appropriate (but not too high)
BP is still not what you’d like
UOP is still not what you’d like
• Time for vasoactive agents
• And perhaps an echocardiogram…
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
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
Inotropic Drugs
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
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
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
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 PVC’s at >5mcg/kg/min
Epinephrine
• Low/medium dose (<0.08 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
Epinephrine
• Indications:
– Depressed ventricular function
– Low cardiac output
– Systemic hypotension
• Side effects:
– Ventricular arrhythmia
– Hypokalemia
– Hyperglycemia
• Central venous access is required
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 1:10,000)
• Repeated q 3-5 minutes during resuscitation
• No longer a role for high dose Epi
– No better outcomes (may be worse)
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
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
What About Vasodilation?
Vasodilators: Basic Principles
• Work = Δ P x V
ΔP-pressure
V-Volume that the heart pumps
• Decreased blood pressure = decreased
work
• Afterload = Pressure
Nitroprusside
• Direct smooth muscle relaxation
• Venous and arteriolar relaxation
– Decreased afterload
– Decreased preload
• Decreases SVR and PVR
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
What About Vasoconstriction?
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)
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
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
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
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
Tachycardia
Sinus Tachycardia is the most
common tachycardia in children
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…
Premature Beats
• Usually in isolation, PAC or PVC (some PJC)
– Not clinically significant
• Atrial irritability is common (check lines?)
– Surgical manipulation also contributes
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
Junctional Ectopic Tachycardia
• Common post-operative arrhythmia
– Originates from AV node
– Particularly in postop TOF/Fontan patient
• Heart rates >150 beats per minute
• Loss of AV synchrony
– Look for AV dissociation
• Slower P wave rate
– Easy to diagnose with pacing wires postop
Junctional Ectopic Tachycardia
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
Supraventricular Tachycardia
SVT ECG
Treatment: Intravenous Adenosine Rapid IV Push
Dose: 0.1 mg/kg
Pre-excitation (WPW)
This patient is at risk for
postoperative SVT!
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
Propranolol
• β-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
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
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
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
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 resolve…be patient!
Conclusion
• Use all your ‘tools’ to evaluate the
postoperative CHD patient
• Use common sense!
• Use teamwork!