This essay will be focusing on evaluating six main factors of intravenous cannulation. They main factors are: on the indications of IV cannulation, the sizes of cannula available to pre-hospital clinicians, sites of cannulation, the contraindications, the risk of phlebitis and intraosseous access. These will be reflecting the effect they have on patient care.
IV access is an invasive procedure that carries risks, in particular with infection at the site of entry (Wedro, 2016). It is for this reason that cannulation is only achieved for particular indications. These include: fluid management, medicine administration, haemodynamic monitoring and blood sampling (Buckinghamshire NHS Hospitals, 2010). In pre-hospital care, IV access is most important in cardiac arrest situations. By obtaining a central circulation access point, adrenaline, amiodarone and fluids are able to take affect quicker than other routes of administration, enhancing the treatment of the patient (Castledine, 1996).
In pre-hospital care, there are five different sizes of cannula that paramedics are able use. The cannulas are measured in a unit called Gauge, which indicates the size of the catheter and the flow rate of the fluid being passed through the cannula (Castledine, 1996). For example, if a rapid infusion of blood or fluids was required in an emergency situation, a larger sized catheter would be used (14-16G) (Waltt and Pirmohamed, 2004). If drug therapy is needed, a smaller gauge cannula would be used (20-22G), as the flow rate on them is suitable. For example, morphine sulphate has to be administered at 2 milligrams per minute up to the appropriate dose, for it to be correctly used and have a maximum effectiveness (JRCALC, 2016), so the correct gauge cannula has to be used to accommodate for the flow rate.
Also, using a smaller cannula increases the comfort of the patient as opposed to a larger size gauge, and also it reduces the trauma to the vein and enables better blood flow (Castledine, 1996). In some cases, the smallest cannula is the only size that can be used, especially in patients that are hypoxic and are peripherally shutting down (Schlag, 1993). Currently there isn’t any published guidelines that states what sized cannula should be used, with only the clinician’s judgement being the decision of cannula size and site of insertion.
Clinicians have a range of sites in which they can gain IV access, however, the choice of vein is very important depending on the reason for cannulation. It is mentioned by Gregory and Mursell (2010) that it is best practice for the clinician to find access on the non-dominant arm. This is so that the patient remains to have independence if an infection was to develop. The most common site of insertion is found to be the Antecubital Fossa (ACF), which contains three main veins, or the back of the hand where the metacarpal veins are located (Hills, 2013). The ACF contains the basilica, median and cephalic, where the median cubital vein is the favoured site in emergency situations (Briggs, 2008). This is due to the veins being the largest, enabling a larger bore catheter to be inserted whilst still allowing adequate blood flow (Waugh et al., 2010). However, it is noted that the ACF should only be an emergency choice, due to it being a flexion point, making it uncomfortable for the patient, reducing their range of movement (McWilliams, 2008). It can also prevent further attempts distal to the ACF if the procedure is unsuccessful and is to damage the vein.
As mentioned, there are no guidelines that outlines a particular site of cannulation, however, best practise is to start distally on the chosen limb. It has been written by Switakowski (2003) that by starting with the dorsal venous plexus allows the clinician to attempt access further up the hand and arm if they are unsuccessful.
Peripheral cannulation can only be used if the patient doesn’t have an effected extremity. If the extremity is injured, infect or burned it needs to be avoided to prevent any further injury or infection risk (Shlamovitz, 2017). There are no official contraindications, with them being based on the clinician’s judgement to how it will effect patient care. It is key for clinicians to ensure that in cases of Myocardial Infarctions that are admitted to the PPCI, that the left arm is the first choice for cannula site (Kumar, 2004). This is because the surgeons in PPCI use the right arm for the sheath insertion, through the radial artery (Anantharaman, 2004). If cannulation is attempted on he right arm and is unsuccessful, it can provide issues with the PPCI team, thus potentially delaying the time of treatment for the patient (Hobbs, 2004).
With IV cannulation requiring to break the skin barrier in order to access the venous pathway, there is a risk of damage and infection to the entry site. One of the most common conditions is called phlebitis, where the tunica media of the vein is damaged and becomes inflamed (Wedro, 2016). There are three types of phlebitis that can arise from breaching the skin.
Mechanical phlebitis occurs when there is foreign object, such as a cannula catheter, moving within the vein, causing irritation and therefore causing inflammation (Stokowski et al, 2009). This happens the most when the cannula is incorrectly sized for the vein and is too big, causing increased friction within the vein and creating additional discomfort for the patient. It has been suggested by Campbell (1998) that placing a cannula in the region of a valve or joint can cause irritation of the venous endothelium and increases the risk of mechanical phlebitis. Uslusoy and Mete (2008) state that this type of phlebitis can be avoided by selecting the smallest sized cannula for its purpose and size of vessel.
Chemical phlebitis occurs from the drug or fluid that is being administered through the cannula (Macklin, 2003). Factors that have a significant effect on chemical phlebitis have been stated by Kohno et al. (2009) to be the osmolarity (concentration) and pH of the substance. Written and Barron (2007) suggest a study that was undertaken by Marc Stranz (2008), where he investigated the effect that pH and osmolarity had on phlebitis, concluding that osmolarity was not a major concern, however, “pH will remain to be a significant cause of phlebitis in peripheral veins”. They go onto to discuss that an abnormal pH can alter the endothelial cell metabolism and thus can promote an inflammatory response subsequently initiating phlebitis (Written and Barron, 2007).
The common type of phlebitis is infective phlebitis, which is due to the aseptic or emergency technique of IV access, which is dependant in pre-hospital care on the environment. Pre-hospital cannulation is not achieved in a desired clinical environment, leaving the site of access increasingly open to infection. Infective phlebitis begins when the protective barrier of the skin and vessel is broken, allowing bacteria to enter and colonise, initiating an inflammatory response from the body (Malach et al, 2006). This cause an infection to develop, and in some cases it can develop into a severe infection leading to thrombophlebitis (NICE, 2015). To prevent this from happening, the BMJ (2017) states that the procedure needs to be aseptic, ensuring that the clinician cleans the site thoroughly, and that any equipment is to be laid out on an aseptic field. This is essential for infection prevention and control, allowing for best patient care.
To summarise phlebitis, it is most commonly attained from the healthcare professional’s technique and experience. It is essential for best patient care that the procedure happens in an aseptic manner, with both the site of entry and the equipment kept clean. If the patient develops an infection it will end with them needing a course of antibiotics and will painful for them, effecting the level of patient care.
In terms of hospital-based care, an IV cannula can stay in place for a maximum of 5 days, under the condition that there is no pain, or redness around it (Buckinghamshire NHS, 2013). It is also suggested that the dressing isn’t tampered with, to reduce the chance of the insertion site getting infected.
An alternative to IV access is Intraosseous Access (IO). IO access is gained through the procedure of inserting a needle into the intramedullary space of long bones, using the humerus, tibia, fibia, femur and also the sternum (Byars, 2011). The long bones of the body contain a large network of vessels, which feed into the central circulation system, operating as a non-collapsible venous access. This form of venous access is particularly important in the use of patients who are suffering from a cardiac arrest or shock, as their body begins to shut down peripherally, resulting in an inability to gain intravenous (IV) access (Guckland, 2014). IO catheters are placed at the distal and proximal ends of the bones (epiphysis), as they provide a thinner layer of bone and a more concentrated level of blood vessels (Vidacare, 2013). In pre-hospital care, intraosseous access is gained using a drill device called an EZ-IO, which gains access by drilling the needle into the intramedullary space of the chosen site (Life in the fast lane, 2015).
The use of IV access is preferred over IO access, as it is less painful for the patient and does not put them in a state of discomfort. Practitioners are encouraged to use the IO device when IV cannulation cannot be achieved, such as a cardiac arrest situation. It is written by Life In The Fast Lane (2015) that IO access should be considered when IV cannulation has failed at two attempts, or the procedure will take longer than ninety seconds. In an article written by Hoskins et al (2012), the American Heart Association guidelines and the Resuscitation Council Guidelines recommend that IO is the first option for vascular access during a pediatric cardiac arrest, and is considered to be the second option during an adult cardiac arrest, following on from a failed IV cannulation attempt (Hoskins, 2012). Although IO is proven to be a more successful vascular access than IV cannulation, IO comes with increased complications and risks. In a table of complications in the West Emergency Medicine Journal (2015) one of the late implications is compartment syndrome, with a risk of 0.6%. Compartment Syndrome occurs when there is an excess pressure that builds in the tissues and muscles in an enclosed space (WebMD, 2005).
Further to IO access, intramuscular (IM) injections of particular drugs can be used. IM injections are used for vaccinations, several drugs and for when vascular access is not accessible (Galan, 2015). IM may be used instead of IV for some drugs as they can provide irritation to the vessel, which can prompt chemical phlebitis. Galan also goes on to explain that IM is preferred to sub-cutaneous injections, where the muscle has a much quicker absorption time than the subcutaneous layer and has the ability to hold more volume.
The use of ultrasound in a pre-hospital environment is a concept that is currently being investigated. There are current trials where clinicians have the ability to use ultrasound in order to locate veins for cannulation. Ultrasound works by transmitting sound waves that travel through the tissues underneath the skin, and get reflected back to a receiver that sits above the skin. This calculates the distance and density of the veins and surrounding tissue and displays them as a two dimensional image (Meenach, 2016). This enables clinicians to view the veins when they are not visible or palpable. The ultrasound also allows the clinicians to view the cannula as it advances into the vein, ensuring correct placement of the catheter. This benefits patient care by reducing the number of attempts for a successful cannulation, thus inflicting less pain on the patient. However, ultrasound units are not a cost effective option, and would be very expensive to provide units in the pre-hospital setting. The clinician operating the ultrasound unit will also require further training, as those who are not competent with interpreting the image carry the risk of penetrating an artery or pushing the cannula into tissue and forcing drugs or fluids into the muscle (Cameron, 2016).
In summary, intravenous cannulation is an important clinical skill that is beneficial to patient care, with drugs and fluids being able to be administered directly into the vascular system for a quick release, increasing the patients care. There are a range of cannula sizes that the clinician can utilize to ensure successful access, with the clinician always making their decision based on the patient care. However, IV has the potential for infections to arise which can cause the patient pain and discomfort with phlebitis. This isn’t the main concern during an emergency, however, the healthcare professional should always take the necessary preparation precautions to prevent an infection from developing. A successful IV access for long term treatment increases patient care due to IV catheters have a 5 day life, as opposed to IO access which has a life of 24 hours, causing pain and discomfort to the patient with insertion and removal of the needle from the bone. There is a future for ultrasound units to be used for cannulation, as they allow for one attempt cannulation, reducing pain to the patient and allowing for emergency drugs and fluids to be administered quickly.
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