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20 Cardiovascular Physiology And Support
Initial management would include the management of the airway, and
every patient in shock should receive 100% oxygen by a face mask until
the shock resolves. If the airway needs a more definitive measure, then Fluid Volume Resuscitation in Hypovolemic Shock
endotracheal intubation needs to be performed because the combination
of shock and respiratory problems has a very high mortality rate.
It is always important to remember that shock is a very dynamic
process, and changes occur rapidly—this is especially true in the Hypovolemic Shock
paediatric population, which requires adjustments that are ongoing in
the management plan.
Fluid resuscitation in the hypovolaemic patient with a large-bore
intravenous cannulae is required, and locations such as the saphenous, 10–20 mL/kg IV LR or NS
femoral, external jugular, and intraossaeous may need to be used. The
goal is to replace the intravascular volume as quickly as possible with
a crystalloid solution, such as normal saline and not dextrose in water.
Normal saline is readily available in most areas of Africa. The expansion Remains Unstable?
effect in the extracellular compartment is greatest, and the cost of the
fluid is inexpensive compared to other fluids. At Kijabe Hospital in
Kenya, we do not use Ringer’s lactate with paediatric patients due to
the presence of potassium in Ringer’s lactate and its effects on a patient Repeat up to 60 mL/kg
with potentially poor renal function. Figure 4.1 presents an algorithm for
treatment of hypovolaemic shock in children. Although this algorithm
may need to be adjusted for each specific clinical dilemma, the figure
will provide a guide for taking the necessary steps needed to prepare the Remains Unstable?
paediatric shock patient for emergency surgery.
In situations whereby the hypovolaemic shock is due to acute blood
loss, the resuscitation team needs to be prepared to infuse appropriate
volumes of blood in an attempt to maximise the oxygen-carrying Add Inotropic Drugs:
capacity of the intravascular volume. The patient’s blood pressure, Dopamine and/or Epinephrine
heart rate, respiratory rate, urine output, and mental status need to be
monitored to help determine the appropriate volume to be infused. Most
who work in Africa will not have access to central venous monitoring
devices; therefore, these indirect measurements of intravascular volume Remains Unstable?
need to act as guides for adequacy of replacement. O-negative or merely
type-specific blood can be infused rapidly in the paediatric patient
who needs blood urgently to survive due to the shock. If the patient
fails to respond to the fluid resuscitation measures, before considering Measure Central Venous Pressure
an inotropic agent such as dopamine, look for an additional cause of
bleeding or decreased cardiac output, such as tension pneumothorax.
Septic Shock Continue LR or NS until CVP greater
Septic shock is associated with microorganisms in the blood and the than 10–20 mmHg
effects of toxic products with an associated inadequate delivery of
oxygen to the tissues. Initially, the oxygen delivery can be high, with
warm and well-perfused tissues, but this can change if lactic acidosis
overcomes the compensatory mechanisms of the paediatric patient due Source: Modified from Litman, RS. Pediatric critical care. In; Litman RS. Pediatric Anesthesia:
to excessive demand for oxygen. Although gram-negative and gram- The Requisites in Anesthesiology. Mosby, Inc., 2004, P 331.
positive organisms are a common cause of sepsis, tuberculosis, herpes, Figure 4.1: Algorithm for treatment of hypovolaemic shock.
and malaria are forms of sepsis seen more often in the African environ-
ment. In an environment where the patients arrive late in their course of The cardiovascular effects that implicate septic shock include lower
distress, septic shock can be severe and the mortality very high in the systemic vascular resistance, increased capillary leak, and increased
paediatric population. venous capacitance, which will directly decrease preload and therefore
The factors that indicate septic shock syndrome are as follows: cardiac output. In patients for whom direct myocardial contractility is
• clinical suspicion or evidence of infection; affected, the inability to provide sufficient oxygen supply for the high
demand results in rapid deterioration. The patient who presents early
• temperature instability (fever or hypothermia);
with “warm shock” will demonstrate a significantly different picture
• tachycardia/tachypnea; and than the delayed presenter who is hypovolaemic with “cold shock”.
The management of septic shock is similar to hypovolaemic shock
• impaired organ system function:
in relation to the need for oxygen and fluids, but these patients need
- peripheral hypoperfusion; to have the aetiology of the septic shock discovered rapidly so that
- altered level of consciousness; the toxic effect can be diminished and eventually removed from the
system. Antibiotics, antituberculosis, or antimalarial drugs need to be
- oliguria;
administered early and in appropriate doses so that the cause of the
- hypoxaemia;
sepsis can be resolved. Disseminated intravascular coagulation (DIC),
- acidosis; and/or renal failure, acute respiratory failure, and even liver failure can be
- pulmonary oedema. caused by sepsis.