“Shock is a medical emergency in which the organs and tissues of the body are not receiving an adequate flow of blood. This deprives the organs and tissues of oxygen and allows the build-up of waste products. Shock can result in serious damage or even death.” (Shock, 2018) In this essay I plan on discussing the management of haemorrhagic shock and the pathophysiology which leads to this condition. As well as this I plan to discuss analgesia and plans for treatment of this form of traumatic shock in the future.
Neurogenic shock is the term used to describe a patient who is facing haemodynamic instability as a result of injury to the upper sections of the spinal cord, this leads to bradycardia and hypotension as a result of damage to the neurological pathways within the spine. (Prabhakar, 2016) states that this loss in autonomic function occurs when the damage effects the spinal cord at the level of thoracic vertebrae six or above. Leading to a form of distributive shock.
When the spinal cord is injured, the patient’s body can lose the ability to fully control the autonomic nervous system; which results in interference with the sympathetic pathways, stemming from the thoracic and lumber vertebrae in the spine. These pathways are used to speed up heart rate and constrict blood vessels to raise blood pressure. (Mack, 2013) states that as a result of this, the parasympathetic nervous system becomes unchallenged, leading to vasodilation and reduction in systemic vascular resistance. As the peripheral vesicles dilate, the patient will reach a state of relative hypovolemia due to the pooling of blood in the increased vascular space (Caroline, 2014.) As well as creating hypovolemia, poor venous return leads to reduced stroke volume and cardiac output.
The equation for cardiac output is: Cardiac Output = Heart Rate X Stroke Volume, this shows the relationship between the functions of the heart and tissue perfusion. For example, if the heart rate slows down then stroke volume must increase to continue an adequate level of perfusion for the body’s cells. If this cannot be maintained cardiac output reduces and tissues no longer have the appropriate level of perfusion. In regards to neurogenic shock reduced heart rate and reduced preload lead to poor perfusion.
As well as the above patients in neurogenic shock is also likely to face bradycardia as the damaged sympathetic nervous system can no longer compete with the activity of the vagus nerve and the reduction in adrenaline and noradrenaline production. This reduces heart rate.
Finally, in patients suffering from Neurogenic Shock it is possible that they begin to entre a state of hypothermia caused by loss of sympathetic stimulation. This leads to the body developing an inability to recognise signals required for thermal homeostasis and a reset in what the body believes is an appropriate temperature. Patients will no shiver despite being cold and will not have appropriate responses to temperature such as vasodilation and constriction. The patients skin will feel warm too as blood begin to pool at the surface of the skin.
As with any patient, facing any type of shock, it is important to support the airway, keep up oxygen levels and maintain blood pressure levels. Without doing so, patients can start to develop cardiovascular collapse, multiple-organ failure and ultimately death. In a patient experiencing neurogenic shock, you should always consider the other injuries in which they have sustained and whether or not this could lead to serious haemorrhaging and further shock (Fox, 2014.) Once you are certain spinal damage is the cause, you should begin to take a full set of observations including SPO2, Lung Sounds, a 12 lead Electrocardiogram, manage the patient’s airway and start the process of immobilisation.
If the patient is not maintaining their own airway, then careful considerations for spinal injury should be taken; in order to prevent further damage a head-tilt-chin-lift should not be performed and instead neutral head alignment and a jaw thrust should be applied. If the provision of this and titrated Oxygen is not sufficient then careful considerations for intubation or a rapid sequence induction (performed by Helicopter Emergency Medical Service) should be made. As concluded by (Crosby, 2006) and backed up by (Krishnamoorthy et al, 2014) the optimal conditions for performing endotracheal tubation with upper spinal injuries is with the use of a fiberoptic bronchoscope. Although this paper provides sufficient evidence to support this, it is important to realise that this paper is designed for the use of anaesthetists, within hospital environments and therefore not one hundred percent relevant to paramedic practice. The same article highlights however that laryngoscopy isn’t impossible whilst a patient is fully immobilised as 64% of patients got a grade three to four view of the glottis. Therefore, further improvements in prehospital care could focus on the use of Video Laryngoscopy or the use of an Airtraq® device in which 96% of patients were successfully intubated whilst immobilised. (Durga et al, 2014.)
In order to prevent further damage to the spine and to avoid worsening symptoms of neurogenic shock, it is important that the patient if fully immobilised and extracted to the nearest hospital as effectively as possible. (Luscombe and Williams, 2003) discussed the most efficient and comfortable ways in which to extricate a patient and compared the use of a spinal board and vacuum mattress. The article concluded that neither option proved better than the other, as they both had advantages and disadvantages which opposed the other. Unfortunately, this study does not add to the little evidence provided on spinal immobilisation, as it was only completed on nine, healthy individuals, fully clothed and in a controlled environment. This is not an accurate representation of the pre-hospital environment and is not conclusive enough to develop paramedic practice in the future. Matters of comfort are also backed by (Chan et al, 1996) which has a greater number of individuals participating but under similar circumstances.
When dealing with neurogenic shock, consideration for relative hypovolemia is vital as excessive fluid therapy can lead to severe oedema and secondary ischemic spinal cord injury as a result; therefore, the placement of a large gauge intravenous cannula will help access for fluids, bloods and any other required medications. If the patient’s blood pressure drops below 90mmHg it is possible that a 250ml boluses of saline intravenous fluid should be administered but be aware that this often has no effect on neurogenic shock (Caroline, 2014.) This practice is backed by (Bernhard et al, 2005) in which it was discovered that hypertension could lead to cerebral ischemia and increased mortality rates. Actions which could further improve cerebral perfusion also include placing the patient in the modified Trendelenburg position but this is only if the patient’s spinal injury is superior and if other injuries are not affected by this action.
In cases where patients are experiencing bradycardia, paramedics should consider the use of drugs such as atropine and adrenaline especially if the patient is symptomatic. These drugs interact with ? and ? agonists to increase heart rate, stroke volume and cardiac output as well as promoting vasoconstriction and vascular resistance. (Cardiovascular failure, inotropes and vasopressors, 2012.) The above presentation is produced for students and trainees of medicine and therefore all information should be correct however the author of the source is not overly clear and this could lead to inaccuracy. (JRCALC 2017) states that Atropine can be used if the patent has a pulse rate below 40bpm and/or a systolic blood pressure below that recommended for their age; this therefore supports the above source. According to the (JRCALC 2017) however, the use of adrenaline is only indicated for cardiac arrests, anaphylaxis and life-threatening asthma.
If a patient becomes hypothermic it is important that you begin to warm them slowly and steadily but the use of blankets, humidifiers and warmed fluids are the most common techniques used. In hospital they will use Bair Huggers™ which are a much more efficient and effective in completing the task in hand.
According to (JRCALC 2017) intravenous paracetamol is very effective in conjunction with opioids as part of a balanced analgesic regimen. Evidence suggests its very good for limb trauma and can be used as an alternative when morphine cannot be provided. The cautions as regards to the use of intravenous paracetamol are only sensitivity and previous use of paracetamol in that day and therefore it would be an appropriate analgesia to consider as the start of pain management for the patient. Paracetamol is deem as a very safe drug and very rarely has any side effects.
In the UK the use of Opioids has been around for several decades and until recently it has proven to be an adequate source of analgesia. In the last few years’ individuals have started to compare the effectiveness of the drug and drugs which work with different receptors in the body. These drugs include Penthrox and Katamine. If you are considering the involvement of Helicopter Emergency Medical Service and Rapid Sequence Induction, then Ketamine works well as both analgesia and as an induction agent. Ketamine has proven to be safe in scenarios where fentanyl hasn’t and it has several benefits when performing Rapid Sequence Induction for spinal cord injuries. Initially this technique was used abroad and eventually brought to the UK for use in trauma scenarios by trained doctors on Medical Emergency Response Teams and the Helicopter Emergency Medical Service. Ketamine’s main benefits include its ability to uphold a patient’s blood pressure, respiratory rate and heart function, making it safe to use with patients facing neurogenic shock. (Gospel, Griffiths and Henning, 2018) According to (Tran et al, 2014) the predominance of nausea and vomiting is also decreased in the use of Ketamine compared to Morphine. This study provides a large range of participants however is predominately based in Vietnam where pre-hospital medicine is very different to that of the UK.
Penthrox is an analgesia manly used in Australia as a hand held inhaler for remote emergency situations, use and trial has been seen across the UK in years past but currently the analgesia is not predominately used due to adverse side effects to both the user and individuals in close proximity to the drug. When the drug was initially developed it was designed for acute trauma situations and for short painful medical procedures. It is important that patients are haemodynamically stable as it can cause hypotension and other issues such as respiratory depression and reduced GCS. Therefore, Penthrox is not suitable for use in patients with neurogenic shock (NPS MedicineWise, 2010.) In a study by (Middleton et al, 2010) Penthrox is described as an analgesia not as effective as morphine or fentanyl but instead one that is efficient of its own accord.
Another analgesic option which falls under the category of opioids is fentanyl.
In conclusion, I have found that although there are several ways in which neurogenic shock should be handled there is not many definitive ways in which it can be treated quickly. Some of the interventions put in place have little to no effect on the outcome of the patient and wide research on spinal cord injuries in the UK and similar countries is not large. I have found that specific studies on analgesia for this issue are in need of further research and development and lots are currently in the process of making this happen. All research papers found tended to be lacking in participants and conclusive evidence could not always be provided. I have discovered that way to treat neurogenic shock in the pre-hospital environment is to prevent further damage and ensure that your patient is as comfortable as they possibly can be until you can transfer them safely to the nearest appropriate hospital.