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Key Questions in CONGENITAL CARDIAC SURGERY
d) guiding percutaneous device placement for procedures, such
as ASD occlusion, pulmonary valve replacement or transseptal
atrial line placement.
Complications associated with TOE are uncommon but can be
•
serious and include:
a) airway — direct trauma or displacement of the endotracheal
tube by the probe;
b) breathing — compression of airways by the probe, which may
impair ventilation;
c) circulation — arrhythmias that may be induced during probe
insertion, mediated by stimulation of the vagus nerve or
sympathetic chain;
d) trauma to the teeth, pharynx, oesophagus or stomach;
e) ischaemic injury — which may be caused by pressure and heat
generated from the probe;
f) bacteraemia.
270
The risks are reduced by having a dedicated, trained TOE operator,
•
which also helps to avoid distractions to the anaesthetist from their
primary responsibilities.
27 Describe the principles of a thromboelastogram (TEG
A thromboelastogram (TEG®) provides near real-time information
•
about blood clot dynamics (Figure 15), guiding peri-operative
management to avoid excessive transfusion and associated
complications.
Heparinase samples distinguish the effects of heparinisation,
•
suggesting protamine rather than coagulation factor use.
Temperature-adjusted samples differentiate hypothermia-associated
•
coagulopathy.
A number of quantitative measures are described, including:
•
a) clot time — which is denoted by the reaction time (R) that
indicates how rapidly a clot is initiated. A prolonged R time
suggests hypofibrinogenaemia or deficient clotting factors.
Fresh frozen plasma (FFP), cryoprecipitate or fibrinogen
concentrate may improve coagulation;
b) clot kinetics — which is denoted by the K time and alpha angle
(α) that provide a measure of speed of clot propagation.
Derangement suggests hypofibrinogenaemia or clotting factor
®
)
7 Anaesthesia and congenital heart disease
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Figure 15. A thromboelastogram (TEG
until a clot first starts to form, when the lines begin to separate; the K time
is from the end of R time until a 20mm amplitude is reached; the alpha
angle is formed between the slope of the two lines (at R and K); MA is the
greatest width between the two curves; and LY30 is the percentage
change in width during the 30 minutes after MA.
deficiency. This may be corrected with cryoprecipitate, FFP or
a specific factor replacement;
c) clot strength — that is defined by:
i) maximum amplitude (MA) — which is predominately a
marker of platelet function. Reduction in MA suggests
platelet transfusion may be required;
ii) G — which is a global measure of clot elasticity but
unhelpful in the choice of treatment product;
d) clot lysis — which is defined by the markers of
fibrinolysis (LY30 and LY60). Values >7.5% suggest
antifibrinolytics (such as tranexamic acid or aprotinin)
may be required.
®
), where the R time is the period
28 What are the advantages and disadvantages of early
tracheal extubation following surgery for congenital
heart disease?
Patients are routinely ventilated following complex cardiac surgery.
•
Prolonged ventilation increases the risk of complications.
271
272
Key Questions in CONGENITAL CARDIAC SURGERY
Pulmonary blood flow, particularly passive flow, such as in a Fontan
•
circulation, is determined by the pressure gradient between the
pulmonary arteries and capillaries. This is reduced by intermittent
positive pressure ventilation and a return to spontaneous ventilation
improves pulmonary blood flow and cardiac output.
Reducing the duration of ventilation is associated with:
•
a) shorter hospital stay;
b) increased patient comfort and parental satisfaction;
c) early recovery of communication, feeding, bowel function and
mobility.
Prolonged ventilation is associated with complications, including:
•
a) ventilator-associated pneumonia (VAP);
b) subglottic stenosis;
c) adverse events, such as accidental extubation, kinking or
obstruction;
d) side effects of sedation and neuromuscular blockade, which
are necessary to facilitate toleration of the endotracheal tube.
For some patients, early extubation is inappropriate and a more
•
gradual weaning from mechanical ventilation is required, including in
patients with:
a) prolonged cardiopulmonary bypass time;
b) significant inotrope requirement;
c) significant comorbidities — such as pulmonary hypertension,
heart failure, chronic lung disease or liver failure;
d) a high risk of TRALI, acute respiratory distress syndrome
(ARDS) or multi-organ failure (MOF) — who tolerate
reintubation poorly and early extubation may not be helpful.
29 What are the features of an effective handover from
anaesthesia to the paediatric intensive care unit
team?
Although personal styles vary, certain key information must be
•
conveyed in a concise and relevant summary, including:
a) basic patient identifiers, including hospital number, date of
birth, age and weight;
b) diagnostic issues, including underlying condition, pre-operative
conditions, previous procedures and allergies;
7 Anaesthesia and congenital heart disease
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c) information on the procedure performed, including repair or
palliation, current anatomical and physiological status,
presence or absence of residual lesions and their description,
relevant information on cardiopulmonary bypass, information
regarding the use of blood and blood products, presence or
absence of arrhythmias, need for pacing, and position and
function of drains;
d) airway issues:
i) ease of mask ventilation and laryngoscopy;
ii) endotracheal tube size and depth;
e) ventilator requirements:
i) ventilator mode and airway pressures;
ii) oxygen requirement;
iii) need for nitric oxide;
f) circulatory issues:
i) site and size of intravascular lines;
ii) details of cardiopulmonary bypass, including duration of
bypass, cross-clamp and deep hypothermic circulatory
arrest;
iii) inotrope and pacing requirements, including underlying
rhythm and function;
iv) use of blood and products and current availability;
v) available or outstanding results;
vi) use of ultrafiltration;
g) antibiotics, analgesia and fluids administered;
h) plans should be discussed, including ideal haemodynamic
parameters;
i) contact details should problems arise.
273
30 What are the negative effects of poorly controlled
postoperative pain?
Pain stimulates a neuroendocrine stress response with wide-ranging
•
adverse physiological and emotional consequences. Many effects
reflect increased levels of circulating catecholamines, including:
a) cardiovascular:
i) increased myocardial workload due to increased heart
rate, SVR, PVR and oxygen requirements;
ii) PVR is increased by raised intrathoracic pressure
induced by crying. Shunting may be altered;
b) respiratory:
i) increased atelectasis, increasing the risk of pneumonia;
ii) hypocapnia (and altered PVR) with prolonged crying;
274
Key Questions in CONGENITAL CARDIAC SURGERY
c) central nervous system:
i) aversion to future procedures complicating ongoing
care;
ii) impaired communication;
d) general:
i) impaired wound healing due to reduced subcutaneous
oxygen partial pressure;
ii) poor mobilisation, increasing complications and delaying
discharge from ICU and hospital.
31 What systems may be used to ensure quality control in
anaesthesia services for congenital heart disease?
Quality can be defined as “the degree to which health services
•
increase the likelihood of desired health outcomes and are consistent
with current professional knowledge”.
Assessing quality requires robust, relevant and measurable
•
outcomes. The complexity of healthcare makes this difficult.
Currently, popular parameters include outcome data, such as
mortality, complications and satisfaction surveys.
Measuring quality in anaesthesia is challenging. Confounding factors
•
make identifying meaningful measurable metrics, specific to the
delivery of anaesthesia, difficult.
Committing to ongoing quality improvement programmes (QIP) leads
•
to maintenance of high standards. Areas for improvement may be
identified from the analysis of adverse events, anecdotal reports or
morbidity and mortality reviews.
Once a problem has been identified, a proposed standard should be
•
defined. Data should be collected defining current practice and
suggesting improvements.
Following any change, the process must be repeated to evaluate
•
impact (Figure 16).
The QIP cycle may have both positive and negative effects:
•
a) positive — such as identify resource deficiencies or
educational needs to increase efficiency;
b) negative — such as frequent changes in practice come at a
cost, including staff disengagement.
The costs and benefits must be balanced. Identifying key
•
improvement areas will yield the greatest benefits.
7 Anaesthesia and congenital heart disease
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Define standards
Local or national
Observe and compare
current practice to
standards
Define relevant local metrics
mкзДдЙг=
бЗЙенбСбЙЗ
Reobserve and compare
practice to standards
Using relevant local metrics
Figure 16. The quality improvement cycle (previously known as the
audit cycle).
Recommended reading
1. Yamamoto T, Schindler E. Anaesthesia management for non-cardiac surgery in
children with congenital heart disease.
13.
2. Subramaniam R. Anaesthetic concerns in preterm and term neonates.
^å~ÉëíÜ
2019; 63(9): 771-9.
3. Checketts MR, Alladi R, Ferguson K, Gemmell L, Handy J, Klein A, Love N, Misra U,
Morris C, Nathanson M, Rodney G, Verma R, Pandit J. Standards of monitoring during
anaesthesia and recovery. London, UK: The Association of Anaesthetists of Great
Britain and Ireland, 2015.
4. Odegard KC, Vincent R, Baijal R, Daves S, Gray R, Javois A, Love B, Moore P,
Nykanen D, Riegger L, Walker SG, Wilson EC. SCAI/CCAS/SPA expert consensus
statement for anesthesia and sedation practice: recommendations for patients
undergoing diagnostic and therapeutic procedures in pediatric and congenital cardiac
catheterization laboratory.
5. Liu Y, Chen K, Mei W. Neurological complications after cardiac surgery: anesthetic
considerations based on outcome evidence.
563-7.
6. Shen L, Tabaie S, Ivascu N. Viscoelastic testing inside and beyond the operating
room.
g=qÜçê~Å=aáë
7. Andropoulos DB. Effect of anesthesis on the developing brain: infant and fetus.
aá~Öå=qÜÉê
2018; 43(1): 1-11.
`~нЬЙнЙк=`~кЗбзо~лЕ=fенЙко
2017; 9(suppl4): S299-S308.
^е~ЙлнЬЙлбзд=fенЙелбоЙ=qЬЙк
`мкк= lйбе= ^е~ЙлнЬЙлбзд=
Implement change
Ensure ‘buy-in’ from
whole team
2016; 48(5): 305-
2016; 88(6): 912-22.
2019; 32(5):
275
fåÇá~å= g
cÉí~ä
276
Key Questions in CONGENITAL CARDIAC SURGERY
8. Haller G, Bampoe S, Cook T, Fleisher LA, Grocott MPW, Neuman M, Story D, Myles
P, on behalf of the StEP-COMPAC Group. Systematic review and consensus
definitions for the standardised endpoints in perioperative medicine initiative: clinical
indicators.
_ê=g=^å~ÉëíÜ
2019; 123(2): 228-37.
Chapter 8
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Paediatric cardiac intensive care
Michael J. Griksaitis, Melanie A. Connett
1 What are the principles of practice for a cardiac
intensive care unit?
Cardiac intensive care units are highly specialised units
•
providing intensive care to a wide range of clinical scenarios and
needs.
Some hospitals operate specialised cardiac intensive care
•
(paediatric and adult) and some care for patients with cardiac
disease as part of the general intensive care practice.
Regardless of the structural model, specialists in cardiac intensive
•
care are called to deal with a child or adult with a cardiac
condition, admitted:
a) with an acute medical problem including stabilisation prior to
cardiotomy;
b) following cardiac operations and/or catheter-based
procedures (diagnostic or therapeutic, electrophysiology
interventions);
c) after non-cardiac surgery.
277
This chapter will focus on children with cardiac conditions, with
•
the principles of intensive care for the adult congenital heart
disease population described in the following chapter.
Key Questions in CONGENITAL CARDIAC SURGERY
2 What are the monitoring tools that are available to the
paediatric intensivist (Table 1)?
Table 1. Common monitoring tools used in the paediatric intensive care
unit.
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aЙлЕкбйнбзе
278
ECG
Invasive arterial pressure
Central venous pressure
(CVP)
All patients have a rhythm strip displayed on their monitor,
allowing the determination of heart rate and rhythm. Many
machines allow for a variety of leads to be selected and can
also determine ST segment changes from the baseline.
Invasive arterial lines measure the arterial blood pressure
beat-by-beat. The pulse pressure can give an indication of
the systemic vascular resistance or diastolic run-off. The
pulse pressure variation (change in peak amplitude of the
systolic pressure), also known as a ‘swing’, can suggest
volume depletion. The trace itself can indicate myocardial
contractility; a steep upstroke implies a greater change in
pressure per unit of time, which therefore suggests good
contractility and vice versa. Cardiac output (CO) can also
be calculated from the arterial waveform (see CO monitor).
Two invasive arterial lines can be used to monitor for
residual gradients across a vessel (e.g. pre- and post-ductal
lines following hypoplastic aortic arch repair). The arterial
line also allows ease of sampling for arterial blood gases
and other blood investigations. Arterial lines are not without
risk, particularly in smaller infants. This includes distal
perfusion problems.
Internal jugular central venous lines can be transduced to
measure the central venous pressure (CVP), which in turn
is an estimation of the right atrial pressure and in the
absence of tricuspid valve disease is an estimation of right
ventricular end-diastolic pressure. The CVP is often used
as an indirect measure of preload and volume status.
However, tricuspid stenosis/regurgitation will affect the CVP
as well as right ventricle disease, such as the restrictive
right ventricular physiology. The normal CVP waveform
consists of a variety of waves (3 in systole and 2 in
diastole), which are altered in the face of arrhythmia or
tricuspid valve disease, leading to characteristic changes
that can be helpful diagnostically. The CVP line also allows
administration of irritant drugs (e.g. vasopressors, TPN)
more safely than peripheral access.
8 Paediatric cardiac intensive care
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Table 1 continued. Common monitoring tools used in the paediatric
intensive care unit.
Left atrial pressure
(LAP)
LA pressure lines are left
áå=ëáíì
following certain
congenital cardiac surgical procedures (e.g. arterial
switch). The pressure reading is a surrogate marker for
the left ventricular end-diastolic pressure and gives an
indicator of LV preload, contractility and afterload. Normal
LAP is slightly higher than the RAP (measured via the
CVP) at 5-10mmHg. LAP lines are not routinely left
áå=ëáíì
as they are associated with risks of air entrainment or
thromboembolic events directly to the systemic circulation
and bleeding on removal. If an air bubble is seen in the
line it must be clamped immediately and action taken.
Pulse oximeter saturation
levels (SpO
)
2
Cardiac output (CO)
monitors
This is a standard monitoring tool and uses the
transmission of light at two different frequencies through
pulsatile tissues to assess the oxygen saturation levels of
haemoglobin. The original calibration means that SpO
2
accuracy is less with extremes of hypoxia (<80%). The
pulse oximeter waveform also informs the intensivist to the
tissue perfusion; a poor waveform or detection of trace
can imply poor pulsatility in the distal tissues. With
improving cardiac output and tissue perfusion the pulse
oximeter trace improves. Direct arterial blood gas analysis
is the most accurate way of determining oxygen saturation
levels and is of importance when caring for the singleventricle cyanotic child for Qp:Qs assessment.
Cardiac output monitoring is a helpful tool to measure the
CO and tissue oxygen delivery. Traditionally this was used
using pulmonary artery catheters. However, for many
reasons this technique is rarely used in the PICU. Modern
CO monitors use a variety of methods including pulse
pressure analysis, bioimpedance, Doppler measurements
or the applied Fick principle to calculate the CO. From
these, the machines often give (indexed) recordings of
cardiac output, stroke volume, systemic vascular
resistance and cardiac contractility. These machines can
be inaccurate, so often it is the trends in values that are
more helpful and need to be used in conjunction with the
clinical assessment of the child.
279
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