Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3612_Библиотеки_им_академика_М_И_Перельмана
.pdf
310
Key Questions in CONGENITAL CARDIAC SURGERY
e) managing arrhythmias;
f) administering diuretics, restricting fluid input and consideration
of renal replacement therapy;
g) consideration of cardiac catheterisation for coronary
angiography if the clinical condition deteriorates or ventricular
arrhythmias ensue.
21 What are the principles of intensive care unit
management for a neonate or infant with a fully
repaired left-to-right shunt?
Following closure of a left-to-right shunt, the circulation should return
•
to normal.
Postoperative concerns relate to the consequences of pre-operative
•
high pulmonary blood flow.
The expected complications of these operations include:
•
a) standard complications of cardiopulmonary bypass;
b) pulmonary hypertension (either persistent or as a crisis), with
an increased risk in cases of:
i) high pre-operative Qp:Qs;
ii) smaller neonates or infants;
iii) delayed closure of the shunt;
iv) pre-operative heart failure;
v) trisomy 21;
vi) pulmonary hypoplasia and possible associated upper
airway obstruction;
vii) Eisenmenger syndrome (reversal of left-to-right shunt
secondary to pulmonary hypertension);
c) arrhythmias and heart block;
d) residual lesions.
The management is partly related to the degree of pre-operative
•
heart failure, the risk of pulmonary hypertension and the age or size
of the child.
All children require diuresis.
•
Low-pressure, high-volume shunts, such as atrial septal defects,
•
AVSD with no ventricular component, unobstructed TAPVC, PAPVC,
are at a low risk of complications and can often be extubated quickly
with minimal challenges.
Children with pressure-loading shunts, such as VSD, multiple VSD,
•
complete AVSD, AP window and truncus arteriosus, often require
milrinone post-cardiopulmonary bypass.
8 Paediatric cardiac intensive care
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
Those at a higher risk of pulmonary hypertension may require
•
ventilation for a longer period of time to observe for stability. Signs of
pulmonary hypertension can then be managed accordingly.
22 What are the principles of intensive care unit
management for a patient with a fully repaired rightto-left shunt and restrictive right ventricular
physiology?
Restrictive right ventricular physiology results from a right ventricle
•
with severe diastolic dysfunction that is stiff, non-compliant, with
small intracavitary volume. It is characterised by end-diastolic
antegrade flow during atrial contraction in the main pulmonary artery,
as seen on Doppler echocardiography.
This physiology is typically seen in patients following repair of
•
tetralogy of Fallot and it is often the result of underlying RV
hypertrophy and the effects of cardiopulmonary bypass.
A restrictive RV results in:
•
a) impaired diastolic filling that produces reducing stroke volume
and forward cardiac output;
b) central venous hypertension as a result of high right atrial
pressures and RVEDP;
c) poor end-organ perfusion as a result of the reduced pressure
gradient, especially in the kidneys and gut.
311
The main complications seen after corrective surgery of these lesions
•
includes:
a) standard complications of cardiopulmonary bypass;
b) residual lesions, such as:
i) pulmonary regurgitation (especially with the use of a
transannular RVOT patch);
ii) residual RVOT obstruction;
iii) residual shunts;
iv) tricuspid valve dysfunction;
c) arrhythmias, especially JET;
d) low cardiac output — which is worsened by restrictive RV
physiology, residual lesions (PR, RVOTO, VSD) and reduced
RV systolic function (if a ventriculotomy was performed);
e) pulmonary hypertension;
f) pleural effusion or chylothorax.
312
Key Questions in CONGENITAL CARDIAC SURGERY
The management considerations will vary for these children
•
depending on the age or size of the patient, degree of RVOTO/RV
hypertrophy and the surgery performed, and may include:
a) managing the general complications of cardiopulmonary
bypass;
b) observing for and rapidly treating any arrhythmias. The
tachycardia with JET is not well tolerated due to the diastolic
impairment and subsequent reduced filling of the RV;
c) ventilation considerations, such as ventilation with the lowest
possible mean airway pressure to maintain adequate gas
exchange is useful, especially as positive pressure ventilation
may exacerbate RV afterload;
d) optimising preload (important due to the RV restrictive
physiology) with the judicious use of fluids and vasopressors,
such as noradrenaline or vasopressin;
e) using inodilators, such as milrinone, to help improve a low
cardiac output state, as well as providing lusitropic properties
for the right ventricle;
f) ensuring any chylothorax or pleural effusions are evacuated;
g) providing adequate diuresis, including early renal replacement
therapy.
23 What are the principles of intensive care unit
management for a neonate or infant following a
Norwood operation, with either a modified BT shunt or
Sano shunt?
The Stage I Norwood operation includes:
•
a) atrial septectomy;
b) reconstruction of the aortic arch;
c) creation of the neo-aorta;
d) systemic to pulmonary shunt (modified BT or Sano).
The key principle of managing an infant following a Stage I Norwood
•
procedure is to ensure an adequate cardiac output with a balanced
Qp:Qs and to deal with the standard complications of
cardiopulmonary bypass.
It is generally considered that the Sano modification provides a more
•
stable haemodynamic behaviour on the PICU postoperatively when
compared to the modified BT shunt. The main reason for the
apparent advantage of the Sano modification is attributed to the fact
8 Paediatric cardiac intensive care
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
that in this case pulmonary flow is systolic and does not affect
diastolic pressure in the systemic circulation. As a result, flow
distribution is not completely reliant on the difference in vascular
resistance between the two circulations, and coronary flow is
superior as it is not affected by the drop in mean arterial pressure, as
with the BT shunt.
A Sano procedure, however, is not completely immune to problems
•
with balancing Qp:Qs in the immediate postoperative period nor
does it seem to provide a significant net advantage to longer-term
morbidity or mortality of the patient.
Issues that can occur with either shunt include:
•
a) standard complications of cardiopulmonary bypass, but in
particular:
i) low cardiac output state;
ii) cardiac tamponade (the chest is often left open electively);
iii) myocardial dysfunction;
b) high pulmonary blood flow, as a result of:
i) high SVR due to insufficient inodilation, pain,
hypothermia or spontaneous fluctuations;
ii) low PVR due to hypocarbia, too high FiO
mismatch or excessive pulmonary vasodilation;
c) low pulmonary blood flow, as a result of:
i) shunt obstruction or even blockage;
ii) pulmonary hypertension episodes, often spontaneous;
d) anatomical complications, such as:
i) pulmonary venous drainage obstruction;
ii) residual aortic arch narrowing;
iii) atrioventricular valve regurgitation;
iv) neo-aortic valve regurgitation;
e) non-cardiac complications, such as:
i) ischaemic colitis;
ii) sepsis.
, BTS/BSA
2
313
Multimodal monitoring of these infants is mandatory to guide
•
adequate oxygen delivery treatment. This is typically in the form of
standard continuous monitoring of parameters such as ECG, BP,
CVP, oxygen saturations, end-tidal CO2, NIRS of cerebral oxygen
saturation, urinary output, blood lactate levels, and arteriovenous
saturation gradient to allow the calculation of Qp:Qs directly,
assuming normal lung oxygenation.
It is important to understand that isolated arterial blood desaturation
•
can be precipitated by several causes, including:
a) decreased pulmonary blood flow and reduced O2pick-up;
314
Key Questions in CONGENITAL CARDIAC SURGERY
b) reduced mixed venous saturation;
c) pulmonary venous desaturation, as a result of poor lung
function.
The general management strategy for these infants includes:
•
a) managing the general complications of cardiopulmonary bypass;
b) balancing Qp:Qs, by maintaining an adequate PVR-SVR
gradient (ideally, in the postoperative setting the Qp:Qs should
be <1);
c) reducing metabolic demand (ventilation, sedation,
normothermia);
d) leaving the chest open postoperatively, with delayed chest
closure;
e) using an adequate inodilator (often milrinone, later converted to
an ACE inhibitor);
f) administering heparin to prevent shunt blockage (later
converted to aspirin);
g) maintaining adequate haemoglobin concentration;
h) avoiding the use of jugular central venous access to preserve
central vessels for the later surgery;
i) delaying feeding because of the risk of ischaemic colitis, with
the early use of parenteral nutrition if enteral feeds are not
tolerated or in the presence of any known gastrointestinal
abnormalities;
j) consideration of repeating the echocardiogram, ECG and
diagnostic cardiac catheter, if difficulties managing the
physiology arise;
k) using VA ECMO support, if inadequate oxygen delivery cannot
be medically optimised.
24 What are the principles of intensive care unit
management for a neonate or infant following a
bidirectional cavopulmonary shunt (BCPS)?
The second stage of the single-ventricle palliation pathway is to
•
redirect the upper body systemic venous return (unilateral or bilateral
SVCs) to the pulmonary circulation bypassing the heart. In the same
operation, a few procedures are undertaken, including:
a) takedown of the BT or Sano shunt;
b) repair of the branch pulmonary arteries (if required);
c) SVC(s) to pulmonary artery branch anastomosis (‘Glenn
shunt’);
8 Paediatric cardiac intensive care
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
d) repair of any additional pathologies, such as atrioventricular
valve regurgitation.
The aim of this procedure is to reduce the volume loading of the right
•
ventricle and is often performed in the first 3 to 6 months of life. It can
also be used for a 1½-ventricle repair, such as with Ebstein’s
anomaly.
Before performing this operation, a diagnostic cardiac catheter is
•
often undertaken to ensure the pulmonary vascular resistance is low,
as the SVC to PA drainage is driven by minimal pressure gradients
and inspiratory passive flow.
The postoperative issues seen following BCPS include:
•
a) standard complications of cardiopulmonary bypass;
b) sinoatrial node injury;
c) SVC syndrome, either mechanical due to obstruction or
physiological due to pulmonary hypertension;
d) pleural effusion or chylothorax;
e) arteriovenous malformations (AVMs) affecting circulation, such
as systemic steal or pulmonary overflow.
315
General management of a child post-Glenn/BCPS includes:
•
a) managing the general complications of cardiopulmonary bypass;
b) appropriate use of pacing (often AAI) for sinoatrial node
dysfunction;
c) appropriate head positioning (30° head elevation) to promote
passive venous drainage through the SVC;
d) anticoagulation (heparin or aspirin), especially in patients with
bilateral BCPS, where the section of the pulmonary artery
between the anastomoses can develop thrombi due to
turbulent flow;
e) administering milrinone, though significant inotropic support is
often not required;
f) ensuring adequate preload to maintain venous drainage to the
pulmonary arteries;
g) using ‘permissive hypercapnia’ (and a mild respiratory
acidosis); the hypercapnia causes the cerebral vessels to
vasodilate and increase blood flow to the head and neck,
thereby resulting in an increased venous return (preload) to the
SVC. The increased SVC flow has to be balanced against the
possible increase in PVR as a result of hypercapnia;
h) using minimal ventilation pressures (without causing
atelectasis) — with the lowest peak inspiratory pressure,
316
Key Questions in CONGENITAL CARDIAC SURGERY
PEEP and shortest inspiratory times as possible; spontaneous
breathing modes on the ventilator as soon as possible;
minimising intrathoracic pressure to promote SVC blood flow
to the PA;
i) aiming to extubate early but only when clinically ready. Whilst
early extubation can promote the passive, lung-bound
cavopulmonary blood flow during inspiration, other benefits of
positive pressure ventilation, such as support of ventricular
function, will be lost;
j) removing jugular central venous lines as soon as possible to
reduce the risk of thrombosis within the shunt;
k) delaying chest drain removal until it is evident that they are no
longer draining.
In the scenario of persistent hypoxia, the management includes:
•
a) increasing the FiO2;
b) avoiding hyperventilation and ensuring a higher PaCO2;
c) ensuring the Glenn shunt and branch pulmonary arteries are
patent with no clot or stenosis, either using echocardiography
or a cardiac catheter;
d) ensuring that there are no pathologies affecting ventilation,
such as atelectasis or pleural effusion;
e) consideration of inhaled nitric oxide;
f) consideration of a diagnostic cardiac catheterisation to look for
collateral vessels or arteriovenous malformations that may
benefit from coiling.
25 What are the principles of intensive care unit
management for a neonate or infant following a total
cavopulmonary connection?
The final stage of the univentricular anatomy palliation is the
•
completion of the Fontan circulation, by connecting the IVC directly
to the pulmonary arteries, via an extracardiac conduit which can be
placed in the pericardial fossa or less commonly an intracardiac
conduit (Figure 8).
In some centres, a fenestration or communication is opened between
•
the conduit and the adjacent wall of the atrial mass. This allows the
preload to increase to the systemic ventricle if the pulmonary
vascular resistance rises, thus reducing the pulmonary blood flow at
the expense of augmented volume and pressure in the systemic
venous reservoir. Whilst this will maintain cardiac output, it does lead
to systemic desaturation.
Rt BCPS
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
RPA
8 Paediatric cardiac intensive care
Lt BCPS
LPA
IC TCPC
Rt HV
IVC
Lt HV
Figure 8. Angiogram of a completed Fontan
circulation, with bilateral bidirectional
cavopulmonary shunts and an intracardiac total
cavopulmonary connection in a child with situs
ambiguous (liver along the midline and straddling
hepatic veins), right atrial isomerism, dextrocardia
and a functional single ventricle. The arrows
indicate the direction of flow, with potential for
slow flow, thrombus formation and reduced
cardiac output due to competing and turbulent
flow at the confluence. Early opacification of the
atria indicates patency of the fenestration. Rt
BCPS = right bidirectional cavopulmonary shunt; Lt
BCPS = left bidirectional cavopulmonary shunt;
LPA = left pulmonary artery; RPA = right pulmonary
artery; IC TCPC = intracardiac total
cavopulmonary connection; Rt HV = right hepatic
veins; Lt HV = left hepatic veins; IVC = inferior vena
cava.
Hospital Southampton, UK.
Image courtesy of Dr. Andrew Ho, University
317
318
Key Questions in CONGENITAL CARDIAC SURGERY
The Fontan circuit is usually completed in older childhood, as the
•
proportion of venous return to the systemic ventricle from the lower
body increases.
The completion of a Fontan circulation allows for better systemic
•
oxygenation and reduction of volume loading on the systemic
ventricle.
Postoperative complications following total cavopulmonary
•
connection (TCPC) include:
a) standard complications following cardiopulmonary bypass;
b) systemic inflammatory response and hypovolaemia — which
produces a more profound clinical impact due to full venous
return depending on passive flow. This can be recognised by
low PA pressures, which are measured through the central
venous line, with a low common atrial pressure;
c) arrhythmias — either sinoatrial node dysfunction or nodal
tachycardias;
d) high pulmonary vascular resistance — which can be
recognised by high PA pressures (that are measured through
the central venous line) with a low common atrial pressure. If
there is a fenestration, the child will also demonstrate
increasing hypoxia;
e) ventricular dysfunction — which can be recognised by high PA
pressures and a high common atrial pressure;
f) pleural effusions;
g) persistent hypoxia — which is often due to a large fenestration,
collateral vessels or high PVR;
h) Fontan circuit failure.
General management strategies are very similar to those adopted
•
following BCPS and include:
a) managing the complications of cardiopulmonary bypass;
b) appropriate pacing to maintain AV synchrony;
c) nursing the child with the head elevated;
d) appropriate anticoagulation (heparin, aspirin or warfarin);
e) ensuring adequate preload;
f) using vasopressors, such as noradrenaline, to manage the
inflammatory response and promote the systemic venous
return to the pulmonary arteries;
g) consideration of an inodilator, such as milrinone, if ventricular
impairment, low cardiac output or AV valve regurgitation are
present;
8 Paediatric cardiac intensive care
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
h) using minimal ventilation pressures (without causing
atelectasis) — with the lowest peak inspiratory pressure,
PEEP and shortest inspiratory times as possible; spontaneous
breathing modes on the ventilator as soon as possible;
minimising intrathoracic pressure to promote SVC and IVC
blood flow to the PA;
i) aiming to extubate early but only when clinically ready. Whilst
early extubation can promote the passive, lung-bound
cavopulmonary blood flow during inspiration, other benefits of
positive pressure ventilation, such as support of ventricular
function, will be lost;
j) removing jugular central venous lines as soon as possible to
reduce the risk of thrombosis within the shunt;
k) delaying chest drain removal until it is evident that they are no
longer draining.
Longer-term complications of the Fontan circuit may require PICU
•
care, particularly in the failing Fontan circuit, including:
a) systemic venous hypertension;
b) pleural effusions;
c) ascites;
d) protein-losing enteropathy;
e) thromboembolic events;
f) ventricular failure.
26 What are principles of management of a cardiac arrest
in the post-cardiotomy neonatal or paediatric patient?
Standard advanced paediatric life support should be initiated on any
•
cardiac arrest. This includes early cardiopulmonary resuscitation
(CPR) and rapid defibrillation, if appropriate.
Consideration of the reversible causes of the arrest, referred to as
•
the ‘4Hs and 4Ts’ must be undertaken quickly (Table 4).
During advanced life support and review of each of the above
•
causes, consideration should be given to some specific interventions
in the post-cardiotomy patient, including:
a) activation of the extracorporeal life support team to cannulate
the child for ECMO;
b) early opening of the chest, followed by internal cardiac
compressions;
c) introduction of inhaled nitric oxide into the ventilation circuit;
319
Соседние файлы в папке Библиотека им академика М.И. Перельмана