Permissive Hypotension for Trauma Below the Neck
Published: 20 October 2020
Published: 20 October 2020
Researchers have found that early, high-dose fluid resuscitation may cause trauma patients experiencing severe haemorrhage to suffer adverse effects such as dilutional coagulopathy or acceleration of the haemorrhage (Kudo, Yoshida & Kushimoto 2017; Das, Anosike & Waseem 2020).
Nickson (2019) describes permissive hypotension, also known as hypotensive resuscitation or low-volume resuscitation, as a controversial and uncommon method of fluid resuscitation that may result in more desirable patient outcomes.
This method is now being discussed by more and more prehospital trauma services across the world as a strategy to replace the older philosophy of higher volume fluid substitution. A systematic review by Mapstone et al. (2003) has shown a significantly higher survival rate in all animal trials when permissive hypotension strategies are applied.
The review also found that out of permissive hypotension, cyclic hyper resuscitation and vasopressors, vasopressors had the worst patient outcomes (Mapstone et al. 2003).
While permissive hypotension can potentially prevent the adverse effects of early, high-dose fluid resuscitation, it has its own unique risks, such as tissue hypoperfusion, that must also be considered (Kudo, Yoshida & Kushimoto 2017). Hence low blood pressure is not the goal but a symptom in order to minimise further clot disruption and haemodilution.
This article relates to permissive hypotension for trauma below the neck.
Permissive hypotension is the intentional under-resuscitation of a patient, where the goal is to maintain a blood pressure that is adequate, but in the lower than normal range (Moore & Moore 2018; Nevin & Brohi 2017; Kudo, Yoshida & Kushimoto 2017).
This is achieved by restricting the amount of fluid administered while the patient is actively bleeding, rather than aggressively resuscitating (Kudo, Yoshida & Kushimoto 2017; Nevin & Brohi 2017).
Permissive hypotension is considered ‘damage control resuscitation‘ that is employed only until haemorrhage control has been achieved (e.g. successful tourniquet on a catastrophically bleeding extremity) (Nickson 2019).
Aggressively resuscitating trauma patients was once considered the standard method of restoring circulating volume and maintaining organ perfusion (Ramesh, Uma & Farhath 2019).
However, during active bleeding, this strategy may be unable to resuscitate the patient, restore perfusion and clear oxygen debt (Nevin & Brohi 2017) due to the increased haemodilution of the blood as well as the associated reduction of the clotting factors. A combination of blood transfusion and fresh frozen plasma would be the gold standard, however, this is highly difficult in a prehospital environment.
Additionally, aggressive resuscitation during active bleeding may lead to serious adverse effects, including:
(NBA 2011; Moore & Moore 2018; Kudo, Yoshida & Kushimoto 2017; Nevin & Brohi 2017)
While aggressive resuscitation increases blood pressure, potentially causing disruption to the clot and consequently, further blood loss (Nickson 2019), permissive hypotension aims to keep blood pressure at a low enough (but adequate) level to optimise organ perfusion and coagulation until haemostasis is achieved (Nevin & Brohi 2017).
Note that low blood pressure is not the goal; rather, it is a tool used as a compromise until the patient is able to undergo a surgical intervention to stop the otherwise uncontrollable bleeding (Nickson 2019).
Permissive hypotension is a method of rapid stabilisation suitable for prehospital settings and should not be used once the bleeding has been controlled in the operating room, where the gold standard is the volume substitution with blood products (Das, Anosike & Waseem 2020).
Generally, permissive hypotension is indicated for haemodynamically unstable patients who are experiencing uncontrolled bleeding (Das, Anosike & Waseem 2020).
It is not considered an appropriate strategy for traumatic brain injury or spinal injury, as tissue hypoperfusion in the central nervous system may cause secondary injury (Kudo, Yoshida & Kushimoto 2017).
Permissive hypotension should be considered on a case-by-case basis and patients should be assessed for prior history that could place them at risk (Das, Anosike & Waseem 2020).
Those who may be appropriate candidates include:
(Das, Anosike & Waseem 2020)
Permissive hypotension is associated with:
(Ramesh, Uma & Farhath 2019; Das, Anosike & Waseem 2020)
(Nickson 2019; NBA 2011; Das, Anosike & Waseem 2020)
When confronted with an acutely bleeding trauma patient, the priorities are to control the haemorrhage; ensure organ perfusion whilst preventing coagulopathy, acidosis and hypothermia from developing; and quickly transport the patient to a facility where definitive haemorrhage control can be achieved (Ambulance Victoria 2019).
The patient should be handled carefully. Limit movement, avoid log rolls and take care during transportation in order to avoid disrupting early clot formation (Nottingham University Hospitals 2019).
If the patient’s systolic blood pressure (SBP) is less than 70 mmHg:
If the patient’s systolic blood pressure (SBP) is 70 mmHg or more:
(Ambulance Victoria 2019)
(Ambulance Victoria 2019)
Note: This article is intended as a refresher and should not replace best-practice care. Always refer to your organisation's policy on resuscitation and permissive hypotension.
Question 1 of 2
True or false? Permissive hypotension is suitable for traumatic brain injury patients.
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