Sepsis is a term used to describe a patient that is suffering from systemic inflammatory response syndrome (SIRS) with the added element of infection (Moore, 2006). Septic shock is defined as a patient with sepsis that is also suffering from life threatening organ dysfunction (Surviving Sepsis Committee (SSC), 2012).
Sepsis is a common condition affecting many veterinary patients, and is shown to have an extremely high mortality rate in human medicine (Dellinger et al, 2012), and the same can be assumed of veterinary patients. It is worth knowing the main clinical signs that may indicate sepsis in patients to be able to alert the veterinary surgeon as quickly as possible. It has been shown that early recognition and treatment of sepsis improves mortality in human patients by up to 50% (Surviving Sepsis Campaign Committee (SSC), 2015).
When the body becomes injured, the normal inflammatory response occurs in three stages: acute, subacute and chronic (Edwards, 2016). In the acute stage, anti-inflammatory mediators are released by the immune system. The acute stage normally lasts a few days. and the damaged tissues begin to repair themselves. In the subacute stage, phagocytic white blood cells (e.g. neutrophils) are released. Neutrophils' main function is phagocytosis, and they are adapted to perform this role extremely efficiently. When there is an invading organism such as bacteria, the neutrophil can attach itself via proteins on their surface. Once the neutrophil is attached to the organism, it begins to engulf it. Enzymes and other chemicals are released which destroy the organism once it has been fully contained. This whole process is part of the immune system's first lines of defence in successfully driving away infection. Macrophages eradicate damaged cells and tissue, so that new tissue can grow in its place (Edwards, 2016). When this subacute stage is prolonged, the inflammation is chronic and the inflammation may spread causing SIRS.
After a trauma (for example a wound) the skin may be red, warm to touch and swollen — this is a normal response and inflammation is localised. Once the body is in SIRS and the inflammation has spread, these signs may persist but there will also be other general clinical signs.
The first veterinary clinical parameters for SIRS were devised by Hauptman et al in 1997 and are shown in Table 1. They found that for a canine patient to be classified as suffering with SIRS they had to have at least two of the criteria shown. For a feline patient, it is said that they should display at least three of the criteria shown, however this has been challenged as there are not currently enough data to support the use of this table in felines (Randels, 2013).
| Dogs (at least 2 or more) | Cats (at least 3 or more) | |
|---|---|---|
| Temperature (°C) | <37.2°C |
<37.2°C |
| Heart rate (beats per minute) | >120 | >220 |
| Respiratory rate (resps per minute) | >24 | >40 |
| White blood cell count (x103) (% of bands) | <6 |
<6 |
A study into nurses in human hospitals on their knowledge of septic signs was performed by Robson et al (2007). They showed that 97% of the nurses knew that a pyrexia was a clinical sign of sepsis, but only 10% knew that hyperlactataemia was significant in these patients. They concluded that nurses need ongoing training in recognising sepsis, as nurses would then be able to identify the important changes to the patient and report them to the doctor.
The registered veterinary nurse (RVN) plays an important role in the care of hospitalised patients as they spend a large amount of time with the patient, recording observations and administering prescribed treatments. Nurses are therefore well placed to pick up on subtle changes in the patients they are nursing.
Kirby's Rule of 20
The Rule of 20 is a list of parameters that are recommended to be evaluated daily or more often in a critical patient (Kirby, 2016). The Rule of 20 can be used as part of a nursing care plan to help ensure that the patient's needs are met or strived for throughout their stay in hospital. Within the Kirby's Rule of 20, there are some things that are particularly useful in the septic patient. For the purpose of this article, some of these rules will be discussed and how they can be applied to nursing the patient.
Blood pressure/fluid balance
Non-invasive blood pressure (NIBP) measurements are often performed in practice by using a Doppler handheld monitor. If a patient is recumbent, then an arterial catheter may be placed in order to take continuous invasive blood pressure measurements. Septic patients often require continuous nursing care and placement of these lines may reduce the amount of time spent taking NIBP measurements, which can then be used to nurse the patient in other ways.
Central venous pressure (CVP) can be measured — a long stay catheter placed into the jugular vein enables monitoring via a manometer, or by a transducer connected to a monitor which can then show a waveform for constant observation. The CVP is useful in showing whether a patient is hypovolaemic or hypervolaemic, and so is especially useful in patients where fluid overload is a concern, such as patients with kidney disease or heart disease (Aldridge and O'Dwyer, 2013). The CVP should read between 0–10 cmH20 for both dogs and cats that are well perfused (Aldridge and O'Dwyer, 2013). Before placing arterial catheters or long-stay catheters, it is important to know the patient's coagulation status. If their coagulation is compromised, placement of these lines may cause excessive bleeding.
Hypotension is common with sepsis, often requiring treatment in the form of intravenous fluid therapy (IVFT) or vasopressors to maintain adequate perfusion (Breton, 2012). With a hypovolaemic patient, it is recommended to use isotonic crystalloid fluids to bolus a patient while monitoring their blood pressure (Boller and Otto, 2009). Dogs can be administered up to 60–90 ml/kg and cats up to 40–60 ml/kg (Boller and Otto, 2009). RVNs should continue to monitor patients carefully while administering the IVFT to prevent patients from fluid overload. In feline patients, this is especially important as heart disease is often very progressed when detected by the veterinarian (Randels, 2013). Challenging feline patients with fluid boluses if they are asymptomatic for heart disease may result in pulmonary oedema due to the rapid increase in hydrostatic pressure within the lung (Adamantos and Hughes, 2015). Colloids are sometimes useful in fluid resuscitation of hypovolaemic septic patients; colloids are large molecules that increase the oncotic pressure of plasma, in turn holding more fluid in the intravascular space (Brooks et al, 2016). Both natural colloids such as plasma, and synthetic colloids such as gelatins are available for use in veterinary practice. For larger patients where fluids are more challenging to replace (such as giant breed dogs), colloids can be used in smaller doses than crystalloid fluids but will have longer lasting effects. Colloids are contraindicated in patients with heart disease and oliguric kidney disease, as risk of fluid overload is larger at smaller doses, and the effects of the colloids last until the body has broken down the molecules or until they leak from the vessels (Brooks et al, 2016).
Glucose
Hypoglycaemia is a common diagnosis in septic patients, and is significant when the blood glucose level is under 2 mmol/litre. Hypoglycaemia occurs when the bacteria in the body use up the available glucose. Luckily, hypoglycaemia is easily diagnosed via a bedside glucometer (Figure 1) and is also treated relatively easily. Dextrose boluses are indicated in patients with a glucose of <2 mmol/litre followed by glucose constant rate infusions (CRIs) of 2.5% and sometimes higher in severe cases (Linklater, 2016).
Oxygenation
Increased respiratory rate in SIRS develops as the cells are working harder than normal to eradicate infection. As a patient becomes septic and develops shock, it is not uncommon for them to develop acute respiratory distress syndrome (ARDS) in which the inflammatory process extends from local inflammation to vasculitis and cytokine release leading to damaged lung tissue (Campbell, 2011).
Oxygen supplementation can be given via many routes. Flow-by is easily accessible to everyone but nasal prongs and nasal cannulae (Figure 2) enable higher flow rates of oxygen to be delivered.
A patient suffering with ARDS as part of septic shock may require mechanical ventilation to be able to receive adequate oxygen delivery to tissues. These patients may require ventilation for a number of days in order to progress through treatment without fatiguing (Moore, 2016).
Heart rate/rhythm/temperature
Even the simplest tasks performed by the RVN may lead to early diagnosis of sepsis in practice. Temperature is an important indicator of health and by taking this regularly any drastic changes will be noticed quickly. It is important to monitor heart rate and rhythm (Figure 3). It is worth noting that feline patients with sepsis behave very differently to canine patients; cats are often bradycardic in sepsis (Boller and Otto, 2009) whereas dogs tend to become tachycardic (Campbell, 2011).
Lactate
Blood samples can also show a variety of changes in septic patients. Hyperlactataemia can indicate hypoperfusion of tissues before a patient becomes tachycardic or tachypnoeic (Savigny, 2006). It is recommended to use blood lactate trends in a patient rather than standalone measurements, as even if the patient is hyperlactataemic (a lactate of over 2.5 mmol/litre) a trend showing the decrease in lactate would still indicate clinical improvement (Savigny, 2006). It is possible to get handheld lactate monitors for use in practice, and these are often invaluable in emergency situations.
Lactate measurements can also be carried out on fluid samples obtained via abdominocentesis or thoractocentesis. If a patient has a septic pleural or peritoneal effusion, the bacteria present create an anaerobic environment, causing the lactate levels to be high in the fluid present. This can be used to indicate sepsis in a patient whose blood lactate levels may not be abnormal (Savigny, 2006).
Coagulation
Coagulation can be affected in sepsis because of circulating inflammatory mediators. Initially, the patient may become hypercoagulable developing microthrombi (clots) that may start to affect organ function while circulating in the bloodstream (Bateman, 2009; Campbell, 2012). As sepsis develops and the patient becomes more critically unwell, they start to become hypocoagulable. At this stage, a venepuncture may cause uncontrolled bleeding. Blood samples should be taken from smaller vessels such as the cephalic or saphenous veins to limit blood loss, and pressure bandages should be immediately applied once the sample is taken. Blood can be sent to the lab for measurements of the prothrombin time (PT) and activated partial thromboblastin time (APTT) or these can be run in house (Hackner and Rousseau, 2015). A useful test that can be performed in house is a plasma D-dimer test; D-dimer is a by-product present after a blood clot has been broken down by fibrinolysis (Moake, 2016). Once a patient is hypocoagulable with elevations in their D-dimer, PT and APTT, they may start to develop disseminated intravascular coagulopathy (DIC). In patients with DIC, the microthrombi cause damage to the organs, but there is also uncontrolled bleeding, depending on whether the DIC is slow evolving or quicker to evolve (Moake, 2016). Patients with DIC often develop petechia which are small blood spots under the skin, most often appearing on the gums of patients or larger bruises on the skin of the abdomen. A useful test to show how a patient is forming clots is to run as thromboelastogram (TEG), which gives a clearer picture of haemostasis (Hackner and Rousseau, 2015).
Renal function
It is important to closely observe renal parameters and the urine output of septic patients as an acute kidney injury (AKI) can occur from hypotension, hypoperfusion and hypoxaemia, all which are concerns with these patients. As septic patients tend to be recumbent, placing a urinary catheter with a closed collection system is the best way to measure their urine output (UOP) and ensures the patient keeps clean and free of urine scalds. UOP is calculated by dividing the produced volume of urine in millilitres by the patient's weight in kilograms and then by how many hours the urine has been produced over: UOP = Volume (ml) ÷ Weight (kg) ÷ Time (hours)
This number is significant as when the kidneys are functioning well the UOP should be at least 1–2 ml/kg/hour (Campbell and Chapman, 2000). Studies in human medicine have shown that a persistent oliguria for between 3 and 5 hours indicated high risk for AKI (Leedhal et al, 2014).
Mentation
Mentation is an important indicator in septic patients; mentation changes in humans with sepsis indicate a decrease in cerebral blood flow (Boller and Otto, 2009). The Modified Glasgow Coma Scale (MGCS) can be invaluable in numericising a patient's mentation, which is especially important when the patient is being cared for by different nurses on different shifts. The lower the score on the MGCS, the worse the prognosis. Several studies have been done on the use of the MGCS in dogs, and it has been shown to be a useful tool in predicting prognosis in patients with head traumas (Platt et al, 2001).
Pain management
Nurses play an important role in identifying pain and communicating progress on its management with the veterinary surgeon. VNs are advocates for the patient and if a patient is painful, VNs should feel empowered to speak up to ensure adequate analgesia is given. Septic patients are often very painful, especially if they are post operative; and dogs and cats display pain quite differently. Cats tend to be much quieter than dogs and will often appear hunched or tucked up (Waran et al, 2007).
There are now many pain scoring systems available to VNs to measure levels of pain in patients so that changes can be seen quickly. Opioids can be given and titrated to effect, and should be considered as part of a multi-modal analgesia approach (Linklater, 2016).
General nursing
Recumbent patients should be turned every 4 to 6 hours to prevent the lungs from collapsing (atelectasis) and to reduce the risk of hypostatic pneumonia. Frequent turning helps reduce the incidence of pressure sores (Winkler, 2016). Padded bedding should also be used to help with this. If a urinary catheter is placed, regular washes of the catheter and surrounding tissues (4 hourly in the author's practice) minimises chances of a patient contracting a urinary tract infection.
If the patient has diarrhoea, keeping them clean is paramount. If the patient has very loose diarrhoea, a Foley catheter can be used rectally with a closed collection system which will avoid any contamination; this will also decrease the need for regularly bathing the patient which may make their skin sore.
Where possible, patients should have their head elevated to reduce the risk of aspiration if they are regurgitating or vomiting. Cots like the one shown in Figure 4 are excellent in providing an accessible area for turning patients without bending and lifting heavy dogs. They also have mechanics for tilting the patient to the desired angle.
Oral care is important in critical patients where they cannot eat and drink normally. Cleansing the mouth is recommended 4 hourly and suction should be on standby in-case there is regurgitation or vomiting to reduce the aspiration risk (Lipke and Carman, 2006).
Conclusion
Patients with severe sepsis will often be recumbent and critical. Nursing care plans and the Rule of 20 are a good basis for ensuring all areas of nursing these patients are covered. Critical care nursing is defined as the care taken or required in response to a crisis (Academy of Veterinary Emergency and Critical Care Technicians, 2014). These patients benefit from intensive nursing and require round-the-clock care, so should be cared for at a 24-hour facility.
Septic patients often require ongoing interventions in response to their observations and have a high mortality rate. RVNs are invaluable in recognising subtle changes in clinical signs; and should feel empowered to take a bigger role in the recognition of sepsis.