Grades of hypovolaemic shock

• Grade 1
  • 15% blood volume (~750 ml)
  • Mild resting tachycardia
• Grade 2
  • 15 - 30% blood volume (750 - 1500 ml)
  • Moderate tachycardia, fall in pulse pressure, delayed capillary return
• Grade 3
  • 30 - 40% blood volume (1500 - 2000 ml)
  • Hypotension, tachycardia, low urine output
• Grade 4
  • 40-50% blood volume (2000 -2500 ml)
  • As above but with profound hypotension

Fluid resuscitation

• Early volume intravascular volume replacement in trauma patients is essential
• The ideal resuscitation fluid is uncertain
• Timing and end-points of resuscitation unclear

Packed red blood cells

• Provide best volume expansion and oxygen carrying capacity
• Needs cross-matching and not immediately available
• Dilutional coagulopathy occurs with massive transfusion

Crystalloid versus colloid resuscitation

• More than 40 randomised controlled trials of crystalloid vs. colloid resuscitation published
• None has shown either type of fluid to be associated with a reduction in mortality
• No single type of colloid has been shown to be superior
• Albumin solution may be associated with slight increase in mortality
• Colloids can more rapidly correct hypovolaemia
• Also maintain intravascular oncotic pressure
• Crystalloids require large volume but are equally effective
• Cheaper and have fewer adverse side effects

Hypertonic solutions

• Subjected to recent intensive investigation
• Can resuscitate patient rapidly with a reduced volume of fluid
• May reduce cerebral oedema in patients with severe head injuries

Oxygen therapeutic agents

• Currently being extensively investigated in clinical trials
• Not widely used at present outside of clinical trials
• Potential advantages over blood include:
  • Free potential viral contamination
  • Longer shelf life
  • Universal ABO compatibility
  • Similar oxygen carrying capacity to blood
• Agents being studied include:
  • Perflurocarbons
  • Human haemoglobin solutions
  • Polymerised bovine haemoglobin

Intraosseous infusion

• Venous access can be difficult in the hypovolaemic child
• If difficulty experienced then intraosseous route can be used as an alternative
• Medullary canal in a child has a good blood supply
• Drugs and fluids are absorbed into venous sinusoids of red marrow
• Red marrow replaced by yellow marrow after 5 years of age
• Less effective in older children
• Systemic drug levels are similar to those achieved via the intravenous route
• Technique is generally safe with few complications

Indications

• Major trauma
• Extensive burns
• Cardiopulmonary arrest
• Septic shock

Contraindications

• Ipsilateral lower limb fracture
• Vascular injury

Technique

• Intraosseous access achieved with specially designed needles
• Short shaft allows accurate placement within the medullary canal
• Handle allows controlled pressure during introduction
• Usually inserted into anterio-medial border of tibia, 3 cm below tibial tubercle
• Correct placement checked by aspiration of bone marrow
• Both fluids and drugs can be administered
• Fluid often needs to be administered under pressure
• Once venous access achieved intra-osseous needle can be removed

Complications

• Complications are rare
• Needles are incorrectly placed or displaced in about 10% patients
• Complications include:
  • Tibial fracture
  • Compartment syndrome
  • Fat embolism
  • Skin necrosis
  • Osteomyelitis

Bibliography

Orlinsky M,  Shoemaker W,  Reis E D et al.  Current controversies in shock and resuscitation.  Surg Clin North Am 2001;  81:  1217-1262.

Moore F A,  McKinley B A,  Moore E E.  The next generation in shock resuscitation.  Lancet 2004;  363:  1988-1996.

Whinney R R,  Cohn S M,  Zacur S J. Fluid resuscitation for trauma patients in the 21st century. Curr Opinion Crit Care 2000;  6:  395-400.