In this assignment the use of Haemodynamic monitoring will be discussed; the author will discuss a patient, (Mary) that came to operating theatres for a procedure. Names that are used have been changed in accordance with the Nursing and Midwifery Council (2004), to protect identities. The specific haemodynamic monitoring used for the patient is, Direct Arterial Pressure Measurement, more commonly termed “A line”. Mary is a 68 year old female who came to theatres for a diagnostic laparotomy. A laparotomy is an opening of the abdomen for surgical intervention (Merck 2007).
This was to be performed as an initial examination could not definitively determine Mary’s diagnosis. It was believed after having an abdominal X ray that a possible bowel obstruction was present. Mary presented with other factors such as pains and cramps in the abdomen, and vomiting. Mary displayed symptoms of sepsis, Tachycardia, Unstable blood pressure, a lack of cardiac stability and she was obese.
Due to Mary’s co morbidities it was decided that Mary would require an Intensive treatment unit (ITU) bed, level 2. With so many co morbidities a safe and effective way to monitor a patient while being anaesthetised is required. Mary may be anaesthetised for a long period of time and possibly a large quantity of blood loss, this is another indication for the use of an A line (Gwinnutt 2004). The world health organisation (WHO) (2006) state it is a basic human right that we be treated with respect and made to feel safe in our surroundings. To achieve this and give optimum care, to monitor Mary effectively it was decided that an A line would be inserted in theatre after Mary had been anaesthetised, but prior to the initial surgical incision.
Direct Arterial Pressure Measurement (A line). An A line is created when separate individual pieces of equipment are connected to created and A line. The A line can then measure direct arterial pressure constantly on a “beat to beat” cycle, this aids a safe, efficient and precise management of ill patients (Pinnock et al 2003). This method of monitoring allows the anaesthetist a method for early intervention with drugs if required. This method of determining blood pressures is known as the “gold standard” of measurements.
With an A line in situ, constant monitoring shows a real time reading of a patient’s arterial blood pressure, systolic, diastolic and mean in an electrical waveform (Pinnock et al 2003). Mean arterial pressure is often abbreviated to MAP this will be seen often in a theatre setting (Rushman et al 2000). With a constant visual display of MAP, systolic and diastolic pressures, this allows the anaesthetist to be able to detect abnormalities within the pressure and restore them to normal (the patient’s normal) (Carrie et al 200).
The A line will also facilitate safe and least traumatic method for obtaining arterial blood samples, that can then be analysed in a blood gas analyser (Gwinnutt 2004).. This will provide the anaesthetist with an accurate display of pH levels of the blood, oxygen and bicarbonate levels also lactate and haemoglobin and electrolyte levels. Advantages of direct arterial blood pressure; ?Accuracy. ?Continuous measurement gives immediate warning of important changes in blood pressure. ?Shape of arterial waveform gives information relating to myocardial contractility and other haemodynamic variables. Facility for frequent arterial blood sampling. Disadvantages. ?Complex to perform. ?Potentially inaccurate if apparatus is not set up correctly.
Haematoma at puncture site. Infection at puncture site, bacteraemia/septicaemia. ?Disconnection haemorrhage. Embolisation. Arterial thrombosis. (Gwinnutt 2004). The insertion of an A line should be done using an aseptic technique (Darovic 2002). Prior to the insertion of the arterial cannulae, the Allen’s test should be employed to ensure adequacy of the ulnar and radial arteries and he patency of the deep palmar arch (Darovic 2002). As Mary is having her A line in her radial artery, the Allen’s test was carried out prior to Mary being anaesthetised. The anaesthetist using both thumbs will locate both the radial and ulnar pulse. Pressure will be applied to both so that the arteries are occluded. Mary was asked to open and close her hand several times; this should result in whitening/ blanching of the hand. After blanching has occurred the ulnar pulse will be released, the hand should then pink up (hyperemia) in approximately 5-10 seconds.
If the hand does not pink up arterial cannulation should not be carried out. The Allen’s test is carried out again except that the radial pulse will be released. If both times the hand achieves hyperemia then it can be assumed that patency of both arteries is good. This will allow for cannulation of the radial artery to take place (Darovic 2002). Once patency was determined the cannulation could take place after anaesthetic induction. The equipment used for an A line are: – 20 gauge arterial cannulae. A giving set with transducer attached.
A Pressure bag. 500mls bag of 0. 9% sodium chloride (normal saline). Two venflon dressings. Before cannulation takes place the arterial line will be assembled. The saline will be place into the pressure bag and the pressure bag will then be inflated to 300 millimetres of mercury (mm HG). The pressure is set to this rate so a continual flow of 3-5 millimetres of saline can flush the cannulae to prevent blood/fluids tracking back up the cannulae and also maintains patency of the cannulae preventing blockage (Hignett 2006).
The tap points within the giving set will have red indicators attached so that it is easily visible that it is arterial and not venous, this helps prevention of drugs being given incorrectly (Darovic 2002). In accordance with NHS guidelines on “improving medication safety” (2007) all drugs given to the patient in the operating theatre would have been labelled and checked by the anaesthetist, to minimise any risk of drug errors. The whole of the giving set will be flushed to purge the system of any air (Darovic 2002).
The trust hospital that Mary attended uses a giving set and transducer that comes as a complete set, this allows for easy and quick set up of an A line. The transducer is an electrical device that enables energy types to be converted from one type of energy to another form of energy. In this medical application the transducer will convert physiological signals to analogue signals. This conversion then allows the electrical monitoring equipment to display the waveform on a display monitor (Magee and Tooley 2006).
There are many different types of transducers that convert energy. The main types are Strain, capacitive and inductive gauges. Of these strain is the most commonly used (Magee and Tooley 2006). This consists of a flexible Diaphragm with an electric current applied across it. When the pressure is applied it makes the diaphragm stretch. This alters the resistance of the diaphragm, so changes will occur in the electrical output, this is analysed and displayed in a wave form on a monitor.
For a transducer to work efficiently it must be calibrated this process is called “zeroing” this can be achieved by opening the 3 way tap to atmospheric pressure and closing the system off to the patient, the transducer and the equipment will then run a self check and zero its self (Darovic 2002). For Zeroing to be accurate the transducer must also be placed in line with the patient’s heart, it may be useful to tape in place (Darovic 2002). The tubing that is used for the giving set part of the transducer kit must be a certain length and thickness, this minimises incorrect readings.
The tube must be of firm plastic so that pressure changes with each beat to beat will conduct through the tube and not be lessened (Darovic 2002). The technique used for arterial catheterisation for the placement of the A line should be carried out using an aseptic technique. The anaesthetist firstly washed their hands to maintain as aseptic work area and then put on gloves, the equipment to be used was placed on a clean trolley that had been wiped with an alcohol impregnated cleaner, and a clean drape was placed on top for the equipment to be placed on by an assistant.
The arm was abducted and the wrist was hyper extended to obtain full visualisation of the radar artery (Darovic 2002). Mary’s wrist was stabilised by an assistant and a surgical gel pad was placed under the wrist to help obtain extension. Because the possible length of the operation was difficult to determine, for Mary’s A line insertion it was decided to have Mary’s arm on an “arm board” this aided the insertion of the arterial cannulae and also made it more natural position for Mary’s arm to be in.
The arm board positions the arm away from the operating table; this greatly helps with access for obtaining blood samples for the blood gas analyser. Mary’s wrist area was cleaned using a chlorhexadine swab to maintain an asepsis technique. This was left to dry naturally for the recommended 30 seconds. The next step was for the anaesthetist to palpate the radial artery. Once the artery is found the 20 gauge cannulae is inserted aiming for the middle of the artery at approximately a 30degree angle from the skin, against the flow (Hignett 2006).
Once into the artery the anaesthetist is trying to achieve ‘flashback’ this is when a flow of blood can be seen in the hub of the cannulae. Once this is achieved the cannulae can then be brought level with the skin and then advanced further proximally by 2-3 mm along the skin until the catheter is fully inserted or to an acceptable depth (Hignett 2006). Now the cannulae is fully inserted it must be fixed into place, due to haemorrhage risk if dislodged, the trust that Mary’s facilitated used a technique for dressing arterial cannulae with 2 standard venflon dressing.
One is placed in the recommended manufactures way; the second is reversed and placed over the initial dressing to ensure extra security. The A line transducer was then attached to the radial cannulae site, all leur lock screws were doubly checked and tightened to ensure there were no leaks. At this point the Zeroing process was done; the open to air closed to patient method was used that has previously been discussed. When readings were obtained on the visual display monitor, the transducer was then secured to Mary’s pillow at approximately heart level.
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