Cardiovascular system difficulty: assessment
In early shock, findings can be subtle. Hypotension is a late sign, so look for a decreased stroke volume (decreased pulse amplitude) and increased systemic vascular resistance (perfusion changes to skin and muscle). In classic shock there are features of decompensation. Late shock is a pre-arrest phenomenon.
· Pulse: tachycardia
· BP: normal but postural drop
· Breathing: tachypnoea
· Limbs: cool and mottled
· CNS: agitated
· Laboratory: mild metabolic acidosis
· Pulse: tachycardia and weak pulses
· BP: hypotension
· Breathing: tachypnoea and grunting
· Limbs: cool, clammy, and pale or blue
· CNS: depressed level of consciousness
· Laboratory: metabolic acidosis
· Pulse: tachycardia and thready pulses; bradycardia is pre-arrest
· BP: profound hypotension
· Breathing: tachypnoea; bradypnoea signifies pre-arrest
· Limbs: cold (blue to white)
· CNS: coma
· Laboratory: metabolic acidosis, multisystem derangement
The patient may have: sweating on exertion or feeding; malaise and irrita-bility; decreased appetite. The physical findings include:
· Tachycardia: ± gallop rhythm on auscultation.
· Tachypnoea: ± wheeze and crackles on auscultation.
· Raised jugular venous pressure: ± hepatosplenomegaly and oedema.
· Pale or mottled and cool extremities.
· Features of the underlying cause: e.g. murmur in VSD or pallor in anaemia.
·CXR: showing cardiomegaly, and pulmonary vascular congestion to pulmonary oedema.
A 12-lead ECG and BP are needed for diagnosis.
If there is haemodynamic instability (i.e. hypotension or poor perfusion), significant bradycardia is present if the HR is:
·<80/min in neonates.
·<50/min in infants.
·<40/min in older children.
These may be:
·Narrow complex: QRS duration <0.1s in children or <0.12s in adolescents (e.g. supraventricular tachycardia (SVT) and atrial flutter). There are no P waves in SVT;
· ventricular: prolonged QRS.
To diagnose hypertension strict criteria should be followed: three mea-surements in non-stressful circumstances with values >2 standard devia-tions above mean for age and sex. Standard charts should be consulted, but, by age, the upper limits of normal BP are:
·<2yrs: systolic BP, 110mmHg; diastolic BP, 65mmHg;
·3–6yrs: systolic BP, 120mmHg; diastolic BP, 70mmHg;
·7–10yrs: systolic BP, 130mmHg; diastolic BP, 75mmHg;
·11–15yrs: systolic BP, 140mmHg; diastolic BP, 80mmHg.
There may be chest pain or features of the underlying cause. Look for:
·Congestive heart failure.
·Pulsus paradoxus (>10mmHg).
When cardiac tamponade is present there are classic signs:
·Distended jugular veins.
·Heart sounds appear distant.
·ECG: decreased voltage, elevated ST segments, T-wave inversion.
·CXR: the heart will look enlarged if an effusion is present.
In cyanotic babies the history and examination can be used to exclude respiratory causes of cyanosis. The assessment also includes the hyperoxia test (measurement of PaO2 in FiO2 100%).
·PaO2 < 13.3kPa (100mmHg): possible cyanotic heart disease.
·PaO2 13.3–26.7kPa (100–200mmHg): possible heart disease with complete mixing and increased pulmonary blood flow.
· PaO2 > 33.3 kPa (>250mmHg): cyanotic heart disease unlikely.