This document discusses the management of pulmonary hypertension after cardiac surgery in children. Key points include: 1. Aggressive sedation and analgesia to avoid stress and triggers for pulmonary hypertensive crises. 2. Positive pressure ventilation for 24-48 hours and paralysis until pulmonary artery pressures decrease. 3. Use of pulmonary vasodilators like sildenafil, milrinone, and inhaled nitric oxide to reduce pulmonary pressures and resistance. 4. Maintaining adequate oxygenation and slightly alkalotic pH to further lower pulmonary vascular resistance. 5. Use of inotropic support as needed to increase cardiac output.

2. Directed by
DR.Karar .A.Ali
department of cardiothoracic surgery
kararbenign@gmail.com

4. It is defi ned as a mean pulmonary artery (PA)
pressure of more than 25 mmHg at rest (or more
than 30 mmHg during exercise), with a pulmonary
vascular resistance of more than 3 Woods units/m2
in the presence of a normal left atrial pressure (i.e.,
<15 mmHg). In the fetus, pulmonary vascular
resistance (PVR) is high because the lungs are filled
with fluid. PVR begins to fall immediately after birth
and reaches adult levels within the fi rst few weeks
of life.

5. In children with congenital heart disease with pulmonary
hypertension or even with normal PA pressure, the
pulmonary arteries may undergo intense
vasoconstriction in response to various stimuli, such as
hypoxia or acidosis. PA constriction then results in
further increase in PA pressure, which may cause acute
RV dysfunction. Such episodes of elevation of PA
pressure may occur in infants in the immediate
postoperative period, after repair of congenital heart
diseases like large VSDs, TAPVCs, and AV canal defects.

6. a pulmonary hypertensive crisis. An acute rise in PA
pressure that causes desaturation, tachycardia,
hypotension, or hemodynamic deterioration

8. An FiO2 of 1.0 is established on return from the
operation theater, which is gradually reduced according
to the blood gases such that the arterial PaO2 is
maintained above 100 mmHg. Physiotherapy and
tracheal suction should be gentle and preceded by a
bolus of sedative plus analgesic and preoxygenation by
hand bagging. Phenoxybenzamine (alpha block) 1 mg/kg
can be given before CPB and again during rewarming. It
is continued postoperatively in a dose of 0.25–0.5
mg/kg/dose every 12 hours.

9. Management of a Pulmonary Hypertensive Crisis
In a pulmonary hypertensive crisis, sedation is
increased and the child is paralysed (fentanyl 2–10
mcg/kg/h, vecuronium 0.1 mg/kg/h). Hand bagging
with 100% oxygen improves the oxygen levels and at
the same time increases respiratory alkalosis by
elimination of carbon dioxide. Additional sodium
bicarbonate is given to maintain metabolic alkalosis.

10. The aim is to reduce the PaCO2 to less than 30
mmHg and pH to more than 7.5. Alkalosis, not
hypocarbia, reduces PVR If possible, the doses of
catecholamines should be reduced and of pulmonary
vasodilators increased to the maximum tolerated
levels. Nitric oxide inhalation is commenced or
increased. Extracorporeal membrane oxygenation
may be considered in the child who remains
unresponsive to the above therapeutic measures

11. Weaning
If the child is stable for a period of 24 hours, weaning of
support should be attempted very slowly over at least
24–48 hours. Inotropes are gradually reduced. PaCO2 is
allowed to rise to 30–35 mmHg, while a PaO2 of over 95
mmHg is maintained. Paralysis is discontinued and
sedation reduced. The child is extubated and only then
are pulmonary vasodilators gradually withdrawn.
Recurrence of crisis would require reinstitution of
measures for the control of PA pressure.

12. Management of Excessive Pulmonary Blood Flow
In a child on ventilator support, when pulmonary blood flow is
excessive (e.g., in single ventricles, transposition of the great
arteries, and postoperatively in a large BT shunt), factors that
cause pulmonary vasoconstriction
need to be initiated to optimize the pulmonary blood fl ow.
Such a strategy will improve systemic blood fl ow and decrease
the ventilation-perfusion mismatch, and permit extubation.
Promoting hypercarbia and a reduction in the
FiO2 even down to 20% will increase PVR and improve the
systemic blood flow. However, an arterial saturation of at least
80% should be maintained.

13. Cyanotic Spells

16. Cyanotic spells occur in cyanotic children of 2 months–2
years age who have a congenital heart defect with
associated subpulmonic obstruction, (tetralogy of Fallot,
tricuspid atresia, transposition of the great arteries or
single ventricle when associated with pulmonary
stenosis). The spell may be initiated by crying, feeding,
hypoxia, or any other stimulus. It is characterized by
irritability and prolonged crying, which progresses to
rapid and deep respiration (hyperpnea), an increase in
the cyanosis, and on auscultation, a decrease in the
intensity of the pulmonary outfl ow murmur.

17. A cyanotic spell may result in seizures, coma, and death.
Emergency management aims to improve pulmonary
blood fl ow and correction of the acidosis. Continuous
ECG, oxygen saturation, and blood pressure monitoring
are initiated. In addition to the management listed
above, any underlying cause such as arrhythmia,
hypothermia, and hypoglycemia are corrected.
In refractory spells, the child may need to be paralysed
and ventilated. Tab propranolol 0.25–1 mg/kg/dose q6–
8h PO may be given to prevent recurrences

18. Potentially malignant pulmonary hypertension spells are
usually iso- or suprasystemic and may induce low cardiac
output, hypoxia, acidosis, or cardiac arrhythmias Sudden
pulmonary hypertensive crises may punctuate the
postoperative course despite accurate surgery and are
associated with significant mortality and morbidity The
primary aim is to decrease pulmonary vascular
resistance and pressure and, if not possible, to avoid
stimulation of the pulmonary circulation and support
right ventricular function through the balance between
pulmonary and systemic vascular resistances and
maintenance of cardiac output .

19. Therapeutic Measures
Therapy should be individualized. The main
measures concern analgesia and sedation,
ventilation, and intravenous and inhaled drugs

20. 1. Anatomic Considerations
First of all, residual anatomical problems should be
excluded as this may be responsible for increased right
ventricular pressure as in the case of residual shunts or
right ventricular outflow tract obstruction. Thus,
anatomic investigations should be performed such as
transthoracic or transesophageal echocardiography or
catheterization particularly if a potential intervention is
anticipated or the patient is not improving.

21. Anatomy is also important as some measures may
help to maintain cardiac output
through a right-to-left shunt used as a “pop
off” for the right side. Preserving a calibrated
atrial septal defect or fenestrated ventricular
defect in the patch is a common measure, but
some authors advocate the use of a valve patch
when a ventricular septal defect is closed
(“flap” fenestration of the VSD patch).

22. 2. Sedation and Analgesia
Agitation and stress are potential triggers for
pulmonary hypertensive crisis and should be
avoided. Well-controlled analgesia and sedation should be
guaranteed while ensuring spontaneous breathing in stable
patients who would be candidates for extubation. However,
unstable patients with frequently or poorly tolerated
pulmonary hypertensive spells should be kept deeply sedated
and eventually on muscle relaxants as required. This is usually
achieved with a combination of opioids and benzodiazepines
administered as continuous infusions and titrated to effect.
Other alternatives are available and depend on specific
institutional protocols:dexmedetomidine, propofol, and
clonidine to mention some. The principle of using minimal
efficient doses should be respected as much as possible.

24. 3. Ventilation and pH
It is essential to adequately ventilate patients
with pulmonary hypertension and to avoid
overdistention or atelectasis, known to be potential
triggers for increased pulmonary vascular resistance.
It is important to remember that pulmonary vascular
resistance is normal at normal functional residual
capacity

25. The current approach is to maintain a normal or
slightly alkalotic pH (as to avoid aggressive
ventilation) and only in rare instances to raise
pH over 7.5. Morris et al. showed that
hyperventilation to increase pH has some deleterious
effects such as an increase in systemic vascular
resistance that may not be tolerated in the
postoperative period

26. Use of sodium bicarbonate or THAM may be
considered in some patients in order to induce
alkalosis without the potential deleterious effects of
hyperventilation

27. 4. Oxygenation
It is well known that hyperoxia provokes pulmonary
vasodilation and that hypoxia induces pulmonary
vasoconstriction. It is therefore important to maintain an
adequate oxygenation (PO2 80–100 mmHg) during a
pulmonary hypertensive crisis and with patients at risk to
develop these problems. This is obtained with the
administration of oxygen and again adequate ventilation
ensuring a proper lung volume. However, the effect of oxygen
seems not so clear in the setting of pulmonary hypertension
after cardiac surgery as well as in the so-called fixed lesions.
One must also remember that high levels of inspired oxygen
may be deleterious and induce lung damage.

28. 5. Vasodilator Drugs
Pulmonary hypertension may be treated with
intravenous or with inhaled vasodilators. Various
intravenous vasodilators such as tolazoline, prostacyclin,
phenoxybenzamine, phentolamine, and nitrodilators
have been used in the past to reduce pulmonary arterial
pressure. However, their lack of selectivity and
inconsistent efficacy are a limiting factor; these drugs
carry a risk of systemic hypotension among others,
which may be undesirable after cardiac surgery

29. Inhaled nitric oxide (iNO) improves right
ventricular systolic function by decreasing
its afterload while increasing left ventricular
preload, restoring aortic pressure and coronary
perfusion In patients with poor left ventricular function, iNO
should be used cautiously since the preload increase may be
deleterious .
Journois and collaborators demonstrated that inhaled nitric
oxide was a useful therapy for pulmonary hypertensive crises
refractory to conventional treatment.
According to Miller et al., even low doses of nitric oxide (2
ppm) appear to be effective in such patients .

32. Patients who remain dependent on NO
and have rebound pulmonary hypertension
upon its withdrawal are candidates to therapy with
sildenafil as a strategy to wean the NO

33. Inhaled prostacyclin is increasingly used as
delivered by aerosol and may overcome the
necessity of a special device to deliver NO.
Several series have been published with
epoprostenol or iloprost .
the major problems is to define the dose to
be delivered as well as the exact dose delivered
when the drug is administered in ventilated
patients .

34. Phosphodiesterase type 5 (PDE-5) inhibitors block
the degradative action of PDE5 on cyclic GMP in the
smooth muscle cells; PDE-5 is increased in PH.
Specific PDE-5 inhibitors, such as sildenafil, promote
an increase in cGMP levels and thus promote
pulmonary vasodilation and remodeling

36. Sildenafil is as effective a pulmonary vasodilator as
inhaled NO. Sildenafil may also be useful
in the setting of inhaled NO therapy withdrawal
in postoperative pulmonary hypertension or in the
presence of PH related to chronic lung disease

37. Intravenous sildenafil has been shown to
potentiate the increase in cGMP in response
to NO in children with increased PVR related to CHD
or in the postoperative state. Nevertheless, sildenafil
infusion has been associated with increased
intrapulmonary shunting and augmentation of
hypoxemia related to ventilation/perfusion mismatch
in the postoperative CHD patient

38. 6. Inotropic and Vasoactive Drugs
After surgical correction of patients with
preoperative pulmonary hypertension or under
significant risk for postoperative pulmonary
hypertensive spells, most centers initiate milrinone
and a low dose (less than 5 mg/kg/min) of dopamine
or dobutamine for right ventricular dysfunction. Low
doses of epinephrine may be added for further
inotropic effect

39. Right ventricular function may be compromised
following congenital heart disease repair because of
cardiopulmonary bypass and direct injury by the surgical
procedure itself Increased pulmonary vascular resistance
further compromises right ventricular function; as a
result the right ventricle becomes dilated and induces an
“intrapericardial tamponade” effect on the left ventricle.
This in turn results in secondary diastolic dysfunction of
the left ventricle which further reduces cardiac output
leading to aortic hypotension and coronary
hypoperfusion of the right ventricle.

40. The effect of the usual inotropes such as
epinephrine or dopamine on the right ventricle
as well as the potential deleterious effect on
the pulmonary vascular resistance is still matter of
debate. It is anyway tempting and justified to use
catecholamines in this setting trying to find a balance
between the potential beneficial and the detrimental
effects. Epinephrine can improve cardiac function but is
known to be deleterious to the myocardium if used at
high doses and for a prolonged period of time. However,
it may still have a place at low dose.

42. Milrinone is a phosphodiesterase inhibitor that may
have some of these properties and it is increasingly
used in postoperative care. The role of type 5
phosphodiesterase inhibitors in the presence of
pulmonary hypertension has a major interest,
but type 3 inhibitors such as milrinone have
been by far more studied and largely used in
pediatric practice

43. Deflnitjon
• Elevation in pulmonary artery pressures (PAP) and
pulmonary vascular resistance (PVR)
• Systolic pulmonary arterial pressure> 35 mm Hg or
a mean PAP> 25mm Hg
• PAP is often compared to systemic blood pressure;
if the systolic PAP is> ½ the systemic blood pressure,
the patient is at higher risk for a pulmonary
hypertensive event/crisis

44. Pathophyatoloav
• Endothelial cell dysfunction: increased vascular
tone and pulmonary artery vasoconstriction
• Secondary increased RV pressure resulting in
decreased RV systolic and diastolic function
• Decreased RV function can result in low cardiac
output syndrome. Presence of an atrial septal defect
or patent foramen ovale may allow a right-to-left
shunt that maintains cardiac output at the expense
of hypoxia

53. Management of post op pulmonary hypertension
Intra operative management;
Ø If PA pressure near or equal to systemic pressure or PVR
increased >5 wood units
Ø Load with Sildenafil 3mg /kg after giving GA
Ø Dopamine infusion started after removing clamp
Ø Milrinone load with 50mics/kg/min over 10 min during CPB
Ø If BP low ,then start adrenaline/nor adrenaline
Ø Fentanyl infusion 2—4mics/kg/min as it blunts the stress
response to the highly reactive pulmonary circulation that
predisposes to pul.HTN
Ø Continue monitoring of PA pressure

54. Post operative management;
Ø Positive pressure ventilation 24-48hrs
Ø Keep well sedated and parlysed until PA pressure (mean)
are half of the mean arterial pressure
Ø Fentanyl 2-4mcgkg/hr while the patient is ventilated
Ø Sildenafil maintence dose;
Ø Blood gases check
Ø Avoid hypoxia
Ø Avoid acidosis and hypercapnia
Ø Keep pH on alkalotic side>7.40
Ø PaCO2 35-40 mmhg
Ø PaO2 80---100mmhg
Ø Hb% >10 gm/dl

55. Sildenafil
Ø 0.5mg/kg in 1st 6hrs
Ø If mean PA pressure are > ½ mean systemic,then
increased dose of sildenafil for next 6hrs 1mg/kg
Ø Continue monitoring of haemodynamics
Ø If still PA pressure are not settleing down, then
increase the dose of sildenafil to 1.5-2mg/kg 6hrly

56. Other Management
Ø Vasodilate to reduce the after load
Ø Inotropic support to increase cardiac output
Ø On operation day, put him/her on prophylactic
antibiotics
Ø Give antacid prophylacticaly

57. On 1st post op day
Ø IF Pt haemodynamicaly stable
Ø Captopril 0.1—0.2mg/kg with ½ dose of milrinon
Ø Aldectone 1mg/kg q12
Ø Digoxin 5microgram/kg q12
Ø Lasix 0.5—1mg/kg q6
Ø Wean off from ventilator when pts are
haemodynamicaly stable

58. On 2nd post op day
Ø Increase dose of Captopril to 0.3mg/kg and turn
off millrinone
For suction Always
Ø Pre-oxygenate and administer a bolus of
fentanyl/relaxant,
Ø Hand ventilate with 100% O2 to vasodilate the
pulmonary vasculature (in PHT crisis)