Introduction
In this assignment I will be discussing blood pressure and how this is applicable to midwifery practice. To look deeper into this, I will explore its history, its methods the craft itself, its importance and how this applies to pregnant woman and the role of the midwife. Pregnant women and new mothers are still dying from pre-eclampsia today. In 2014-16, 6 women from 100,000 pregnancies died from pre-eclampsia. Although not the most significant cause of maternal death, it still remains prominent in today’s society, with no evidence for an ongoing decrease in coming years. (Knight et al. 2018). High blood pressure remains one of the most significant identifiers of pre-eclampsia, involving a reading, on more than two occasions, a blood pressure of systole higher than 140 or diastole higher than 90: this makes the skill essential in midwifery practice; allowing us to identify women of high risk and in turn, making appropriate referrals across the health care system. (Robson et al. 2014).
Definition and Methods of Taking Blood Pressure
Blood pressure is defined as “pressure or force exerted by blood against arterial walls”. (Tiran 2012, p28). There are two main methods of taking an individual’s blood pressure, the auscultatory method and the oscillometric method. The auscultatory method of taking blood pressure is most common and involves the use of a stethoscope and sphygmomanometer to detect acoustic sounds made by arteries, known as Korotkoff sounds. This is a well-practiced method as it is completely non-invasive and if performed well, accurate. However, the method can pose difficulty in environments with a high level of noise or where the individual moves, lowering the reliability of the reading. This can sometimes be difficult within Midwifery practice where practitioners are often in clinics or hospital environments where there are a number of women walking around, equipment making noises, visitors and partners present, or within the context of pregnant women, where they are uncomfortable due to the added weight and pressure from baby and feel the need to move around more. This method also requires an increased amount of training and practice to perfect the skill by practitioners. However, its increased level of accuracy once mastered cannot be questioned; ultimately it is the balance between accuracy, and cost and time of training practitioners fully. (Sebald, Nahr and Kahn 2002). Unlike the auscultatory method, the oscillometric method of measurement includes use of an automated, electrical cuff and takes blood pressure by recording a number of small pressure pulses while the cuff is pumped up, or air released, from the systolic pressure to the diastolic pressure. The blood pressure is then generated by analysing the amplitude of those pulses. This method is often favourable in contemporary society due to ease of its use, little training requirements, reduced cost of equipment and the ban of mercury, which is one component of the generic sphygmomanometer; as well as the non-invasive natural of the procedure, as with most blood pressure methods. However, it is important within this method that the practitioner selects the correct cuff size for the correct limb of the individual, and further recommendations such as the positioning of the limb and support to said limb, as these factors can all affect the reading of the blood pressure. (Alpert, Quinn and Gallick 2014).
How to Take Blood Pressure
All health practitioners, including midwives, are trained to obtain a manual, auscultatory blood pressure, in case of inaccuracy or breakdown of automated machines in practice. In order to do so, full informed consent is agreed between practitioner and woman, this means full explanation of the procedure, how it will feel and the answering of any questions that arise. Following that, within midwifery care, encouraging the woman to empty her bladder allows for more comfort during the procedure. The practitioner then gathers their equipment, a stethoscope and sphygmomanometer, using hands that are freshly washed and dried. It is important that any pregnant woman has been resting for 5 minutes on taking blood pressure which may mean letting her sit for 5 minutes; as she may have been rushing around to get to her appointment, dropping her other children to school, for example. The position of the woman is also important, she should have her legs uncrossed with her upper arm exposed, ensuring no restrictions from clothing or jewellery, her palm should face toward the ceiling. The blood pressure cuff will then be placed 2-3cm above the brachial artery which can be palpated prior to doing so, the bladder of the cuff sits above the artery centrally allowing even pressure on inflating the cuff. Ideally, the sphygmomanometer should be level with the woman’s heart, and the valve is firmly closed to allow inflation. The cuff is then pumped up, with the stethoscope in your ears, until the pulse sound disappears, plus 30 mmHg, the valve is opened to slowly release air, once the pulse is heard again, the systolic pressure is recorded. Further air is released at 2-3mmHg per second until the pulsating sound disappears, this is recorded as the diastolic pressure. Take the cuff off the woman’s arm and help her to rearrange her clothing, tell her the findings of the procedure and explain whether or not this is normal, if not, what this indicates. The essential final step is to record the findings, for midwifes, this is most commonly in the woman’s green maternity notes. (Johnson and Taylor 2010).
Importance of Blood Pressure Monitoring
There is great importance on blood pressure in maintaining normal functioning of organs in the body, the systemic arterial blood pressure in particular, maintains blood flow into and out of the body’s organs. This being said, it is important that blood pressure is kept within normal limits. The range for normal blood pressure is variable and changes, currently, it is defined as a systolic blood pressure less than 120 mmHg and a diastolic of less than 80mmHg. (Viera 2007). If blood pressure is raised, damage can be done to the vessels of the body which may lead to blood clots or bleeding from sites of rupture. However, if it becomes too low, then the tissues may not receive enough blood which can be dangerous for vital organs such as the heart, brain or kidney, or which starvation of oxygen means they are unable to function adequately. The systolic pressure is created when the left ventricle contracts and moves blood into the aorta, it is the pressure produced within the arterial system which we record as systolic. The diastolic pressure arises when the heart is at rest after blood leaves it, the pressure within the arteries is known as the diastolic pressure. The difference between the two values is known as pulse pressure. Blood pressure is determined by two factors: cardiac output and peripheral resistance. The value of blood pressure is altered if either of the two change, however the body usually adjusts to deal with this. Cardiac output is determined by stroke volume and heart rate, an increase in this increase systolic pressure more than diastolic pressure. Peripheral resistance is maintained by the constriction and dilatation of the arterioles. Vasocontraction of the arterioles causes the blood pressure to rise, and vasodilation the opposite. (Waugh and Grant 2014).
Changes to Blood Pressure in Pregnancy
Normal pregnancy has little effect on blood pressure; the slight increase in cardiac output and vascular capacitance has little effect on the systolic pressure of the blood. However, there is some impact upon the diastolic pressure in pregnant women, especially in the first two trimesters, but this is considered normal. The diastolic pressure can be lower due to the development of new vascular beds for the fetus and the relaxation of peripheral tone due to the increase amount of progesterone in pregnancy, the resultant effect is decreased resistance to flow, lowering the diastolic blood pressure. This decrease in pressure normally returned to prepregnancy values in the third trimester. These changes are the result of changing prostaglandin levels; the amount of PGE2 and prostacyclin increase in early pregnancy, these are responsible for vasodilation, causing a lower diastolic pressure. This causes an increased difference between systolic and diastolic pressure, meaning the pulse pressure is increased in pregnancy; these changes are considered physiological for pregnancy, as long as within limit. (Coad and Dunstall 2011).
History of Blood Pressure
It took many years for the commonly used sphygmomanometer to develop; the mercury sphygmomanometer was first introduced by Scipione Riva-Rocci in 1896 and could only be used to measure the systolic blood pressure but was easy to use and gave reliable results in practice. This equipment consisted of an elastic inflatable cuff situated on the upper arm, as still practiced today, a rubber bulb to inflate the cuff and a glass manometer filled with mercury to measure the pressure in the cuff. It was used to measure systolic pressure by palpating the radial pulse and once disappearing on palpation, recording the cuff pressure. This technique however, could not be used to measure the diastolic pressure. Prior to this reliable, non-invasive phenomenon method, the first recorded invasive measurement of blood pressure was in 1733 by Stephen Hales who spent years measuring the blood pressure of animals and recorded this by determining the quantity of blood in a horse. He was also the first to introduce the idea that blood pressure was in proportion to the size of the individual, however was criticised for being invasive, and techniques which included positioning glass tubes into arteries, being inappropriate for clinical practice. The units of blood pressure, being mmHg, which are still used today, were first introduced by John Leonard Marie Poisseuille in 1828. Poisseuille also improved the original mercury sphygmomometer by swapping the short tube of the manometer to a much longer one, then called the haemodynamometer. From this, the development of methods which visually displays the change of blood pressure were founded by Karl Ludwig who added a float to the mercury manometer which scribed the arterial pulse wave onto a recording cylinder, called a kymograph, but was still an invasive method of connection of apparatus to an artery. The first method of non-invasive measurement was introduced in 1880 by Samuel Siegfried Karl Ritter von Basch. This equipment was formed through knowledge of the oscillatory method which allowed both systolic and diastolic pressure to be measured – the change from maximal oscillations to smaller ones implied the diastolic pressure. The final breakthrough in the development of the sphygmomometer was the introduction of Korotkoff sounds by Nikolai Korotkoff who used a stethoscope and the apparatus formed by Riva-Rocci to demonstrate how certain sounds could be heard during the decompression of arteries. This formed the auscultatory method of blood pressure measurement and was more reliable than palpation techniques, this became the standard practice in healthcare, of which we still use to this day; modernised due to the band of mercury use in healthcare. (Roguin 2006).
The Role of the Midwife
Hypertension is one of the most common medical disorders seen in pregnancy and is still a large cause of maternal death. This gives the monitoring of blood pressure great importance in midwifery practice, hence NICE (2008) recommends all midwives should measure blood pressure at every antenatal visit, in order to screen for pre-eclampsia. Further recommendation says that more frequent measurement should take place where a woman has any risk factor for pre-eclampsia. This allows midwives, where significant hypertension is present, to refer women to appropriate practitioners for follow up care and tests. It is important that midwives adhere to these NICE recommendations as pregnant women who have hypertension are more at risk of having preterm delivery, low birth weight and neonatal death. (The Royal College of Midwives, 2014). Due to the importance of the procedure, it is the midwife’s duty of care to record blood pressure and act accordingly. Within The Code, the Nursing and Midwifery Council (2015) says all midwives should practice effectively, this includes assessing the need for treatment and care without too much delay, which is in line with the NICE recommendations – a midwife will adhere to the recommendations by monitoring blood pressure at every antenatal appointment, but will assess the need for the procedure by considering risk factors the woman may have, allowing them to be coherent to The Code and provide appropriate care to women. Blood pressure can highlight a number of potential pregnancy complications such as fetal growth restriction, pre-eclampsia, preterm delivery, placental abruption (The American College of Obstetricians and Gynaecologists, 2018). As a result, not only is the monitoring of blood pressure important for the woman in preserving the safety of herself and her baby but is also the duty of care of the midwife in order to assess the woman’s current health and wellbeing and make appropriate referrals if necessary.
Conclusion
After having explored blood pressure deeply, I can conclude that it remains a very prevalent midwifery skill during care of women in pregnancy as it can highlight a number of complications, early enough, that the midwife can act accordingly, making appropriate referrals to other health practitioners for further care to avoid bad circumstances and outcomes for both mother and baby, ultimately avoiding mortality. The art of monitoring blood pressure in today’s healthcare practice has been adapted through history to become non-invasive, simple and reliable, and allows practitioners to measure and assess the pressure of the blood on the walls of arteries in the body. All midwives have a duty of care to woman, and by measuring their blood pressure at every antenatal appointment, a procedure which is quick and requires minimal training of said practitioners, they preserve the safety of women and uphold their reputation by doing in depth assessments of each woman and her baby to identify any complications, such as pre-eclampsia and avoid negative outcomes.