Integrating research into daily practice: a consultant's question to a group of nurses about the effectiveness of the Trendenlenberg position, prompted research that changed nurses' practice.

NURSING IS a dynamic process and decision making must be dependent on clinical judgement, a key component in the art of nursing. It is the mutual relationship established between research and practice that determines the direction of research, and is the means by which it makes its contribution to practice.

Nursing research helps define the parameters of nursing. (2) The theoretical formulations supported by research findings can potentially become the foundations of evidence-based practice, which has emerged as a widely accepted paradigm for contemporary professional nursing. (1)

By understanding the research process, nurses are able to interpret, evaluate and determine the credibility of research findings and are able to practice using evidence-based care, with the best possible outcomes for their clients. (1) Education helps integrate and make the links between research, theory and practice stronger, helping to reduce the existing gaps between theory and practice and research and practice. This can have a positive impact on how nurses think and feel about their readiness to critically look at their actions, analyse outcomes for clients, have a willingness to research and have the ability, skills and confidence to use research findings in practice, and with sound judgement. (3)

This article will discuss a nursing action for hypovolemic clients and demonstrate the application of research, by following a critical thinking decision pathway.

The patient, a 62-year-old woman with a long cardiac history, was hospitalised for investigation of a gastro-intestinal bleed. On admission she was very pale and tired, she had passed large quantities of melaena at home before being brought in by ambulance, and had already spent several hours in the emergency department. A verbal handover was received and an initial assessment was commenced. Her blood pressure was very low so the bed was tilted, making the patient's head lower than her legs, ie the Trendelenburg position. The patient appeared to tolerate the position initially, but soon asked to have the head of her bed raised as she did not like the sensation of lying at that angle. It was explained to her that the position would help raise her blood pressure and was commonly used for hypovolemic patients and to prevent shock, which was a concern because of her blood loss.

The Trendelenburg position is the elevation of the pelvis above the horizontal plane, in a supine position, and was introduced in the latter part of the 17th century as a method of facilitating surgical exposure of the pelvic organs, by Fredreich Trendelenburg. It was later developed as an antishock position during World War One, and gained widespread popularity, despite lack of evidence for its effectiveness. (4) Patients with severe hypovolemia (low cardiac filling process and hypotension (4)) are placed in this position, head down, legs elevated for hemodynamic effects.

A further assessment identified the client was experiencing some breathing difficulties, at which time the head of her bed was returned to the level position, and her legs remained elevated, the modified Trendelenburg position. The client was in this position when the consultant began his rounds. At the completion of his rounds, he asked the nurses if they had read any research articles on the effectiveness of the Trendetenburg position for improving cardiac output, hypovolemia and shock.

This question became the trigger to question the efficacy of the nursing action in relation to the best outcome for the client. The trigger is the initiator of a critical thinking decision pathway that guides nurses as they assemble research literature, critique and evaluate its relevance, and make personal decisions about changes to their future practice. (1)

The organisation's protocols and guidelines supported the use of the Trendelenburg position at this hospital. Discussions within the nursing team and the multi-disciplinary team produced varying points of view and different philosophies of care. But these discussions quickly identified that many nursing actions are, as recognised by some commentators, (2) based on tradition and age-old practices that have not been challenged or evaluated for their effectiveness.

Traditional management of the hypovolemic, hypotensive or shocked patient has included elevating the foot of the bed as a means of increasing blood flow to the brain. The effectiveness of this practice seems contradictory to current physiological homeostatic theories. (5) The initial elevation increases the blood flow to the brain and distends the carotid arteries. In doing this, the baroreceptors, part of the blood pressure regulatory mechanism, send messages to the brain stem, which instigates peripheral vasodilation and hypotension as a compensatory mechanism. This is a contradiction to the desired effect for the client. (5)

Rapid fluid replacement

The loss of blood externally that this patient experienced is defined as absolute hypovolemia. The major priority treatment for hypovolemic and haemorrhagic shock is rapid fluid volume replacement. (6) The positive effect for the client became apparent when her cardiac output, arterial blood gases and blood pressure returned to an acceptable therapeutic range after receiving intravenous administration of normal saline and three units of blood.

The client was monitored very carefully during her fluid administration. Her heart rate and rhythm were monitored for detection of changes in her cardiopulmonary status. An accurate measurement of her blood pressure was important because the systemic pressure influences tissue perfusion and myocardial oxygen demands. (6) Arterial blood gases were taken to detect any acid-base abnormalities, her level of consciousness was regularly assessed and an accurate fluid balance chart was maintained. The assumption was, that by placing the patient in the Trendelenburg position, this was also beneficial to her recovery.

Venous return 

Studies on post-operative patients who had evidence of severe hypovolemia and low blood pressure have shown very little effect on cardiac output from the Trendelenburg position. (4) Studies showed significant increases in mean arterial pressure and wedge pressure, while cardiac output remained the same. (7) This indicates the Trendelenburg position does not promote venous return to the heart. The increase in wedge pressure can be explained by an increase in intrathoracic pressure caused by the displacement of the diaphragm during the body tilt (7), which, in this patient's case, also caused her to experience difficulty in breathing, which was not at all conducive to her recovery.

The venous system is designed to absorb pressure and act as a volume reservoir. When pressure is applied to a vein, it distends and increases its volume capacity, which limits any change in venous pressure. This then counteracts any increase in the pressure gradient between peripheral and central veins. (8) The venous system is more likely to transmit pressure when the veins are overloaded and less distensible, so as long as the client is receiving sufficient fluids, it is more beneficial therapeutically to be comfortable, allowing the body's natural mechanisms and systems to function effectively, rather than having to fight against further resistance from unnecessary positioning.

A survey sent out to 1000 critical care nurses identified 90 percent of respondents used the Trendelenburg position, mostly for the treatment of hypotension, and used this intervention as an independent nursing action, having learned about the position from nursing education, colleagues, supervisors and physicians. Eighty percent believed the use of this position would improve hypotension. (9)

From results of five separate research studies, researchers estimated this position centrally displaces only 1.8 percent of total blood volume, which is too little to affect significant clinical improvements. (10) An open-ended survey question to nurses asking them to share their understanding of the Trendelenburg position identified four themes. Firstly, the position adversely affects ventilation, because gravity works against the diaphragm and lungs. Secondly, it can increase intracranial pressure and is dangerous in patients with neurologic damage. Thirdly, it can stimulate vasodilation by causing baroreceptors to sense blood pressure higher than it really is. Lastly, there were nurses who believed, be cause beds were equipped with this positioning feature, the position was effective. (9)

These findings highlighted a nursing intervention that has been based on ritual rather than scientific evidence.

As more knowledge about the complex physiology of blood pressure and cardiac output is known, critical care nurses are able to use nursing research as part of their critical thinking and clinical judgment to determine the most effective ways of caring for their clients. (9)

Just as the patient objected to a head down, tilt position, research has shown that conscious patients usually do object to the Trendelenburg position after a very short time. (11) It is now recognised as potentially harmful in the presence of cardiac, pulmonary, ocular, and central nervous system pathology, and essentially useless for vascular resuscitation. (11))

The favoured position is now the contoured supine position, ie having the head raised as well as the legs elevated. Researchers and practitioners believe this position deserves serious consideration and further investigation. (11)

In a preliminary study to determine the effects of the Trendelenburg position on cardiac output and oxygenation in 23 critically ill patients, five patients were unable to tolerate the position at all. The remaining 18 showed no statistically significant changes, so the study could not provide support for the position as a means to influence hemodynamic parameters. (8) A prospective, self controlled, sequentially designed study on a further eight patients also failed to provide evidence associated with an improvement in cardiac output or in crease in blood pressure. (7)

Despite its widespread use, the Trendelenburg position has not been shown to provide any consistent beneficial erects for patients. When planning positioning manoeuvres, critical care nurses need to consider these results in relation to the specific needs of each client. Many nursing studies provide evidence now that ritual based theory still underlies interventions used in the care of critically ill patients, and nurses are still relying on an outdated knowledge base not supported by current literature. (9) With no evidence of consistent hemodynamic benefit, the routine use of the Trendelenburg position should be abandoned. (12)

The hemodynamic and cardiopulmonary responses to positioning patients like the patient in this article should be evaluated in conjunction with other therapeutic modalities, such as those designed to preserve skin integrity and improve comfort for the client. (5)

The process that followed the initial question regarding the efficacy of the Trendelenburg position stimulated discussion, prompted a review of the organisation's protocols and procedures, individual nursing actions and philosophies of care, and initiated a search for relevant and current literature to support that action.

Research is of little value if the findings are not used to improve patient care. (3) The conceptual use of relevant research influences peoples' thinking, also known as knowledge creep or cognitive application, and is often used by individuals who read and incorporate research into their critical thinking in practice. (1)

It is not always possible to make immediate changes to organisational protocols and guidelines but what does happen, as experienced from an individual perspective, is the thinking of the team is influenced by research findings. Exposure to new knowledge occurs and enables the individual to make choices to incorporate findings into their critical thinking, decision-making and nursing actions, using sound clinical judgement. Nurses are able to use research findings to enhance nursing management. (2) By eliminating ritual-based nursing actions, such as in this case, nurses become professionally accountable to their clients and help nursing to achieve its own professional identity.

Every nurse has an important role in using nursing research, and it is the behaviours and attitudes of practising nurses that are critical to the success of any efforts to base nursing interventions on research findings. Research, in this case, identified the Trendelenburg position to be outdated and the current suggestion is that the contoured supine position deserves further investigation. This type of research can be, and should be, conducted by nurses. It plays a pivotal role in improving the quality and efficiency of nursing care and helps develop a climate of intellectual curiosity in the profession.

REFERENCES

(1) Beanland, C., Schneider, Z., LoBiondo, G. and Haber, J. (1999) Nursing research: methods, critical appraisal and utilisation. Sydney: Mosby.

(2) Polit, D. and Hungler, B. (1997) Essentials of Nursing Research: Methods, Appraisal and Utilisation (4th ed). Philadelphia: Lippincott.

(3) Smith, J. P. (Ed) (1994) Advanced nursing series. Research and its application. Oxford: Blackwell Scientific Publications.

(4) Marino, P. (1998) The ICU Book (2nd ed). Baltimore: Williams and Wilkins.

5) Manley, K. and Bellman, L. (Ed.) (2000) Surgical nursing: advancing practice. London: Churchill Livingston.

(6) Lewis, S., Heitkemper, M., and Dirksen, S. (2000) Medical-surgical Nursing, Assessment and Management of Clinical Problems (5th ed). St Louis: Mosby.

(7) Sing, R., O'Hara, D., Sawyer, M. and Marino, P. (1994) Trendelenburg position and oxygen transport in hypovolemic adults. Annals of Emergency Medicine; 23, 564-567.

(8) Ostrow, C., Hupp, E. and Topjian, D. (1994) The effect of Trendelenhurg and modified Trendelenburg positions on cardiac output, blood pressure and oxygenation: a preliminary study. American Journal of Critical Care; 3: 5, 382-6.

(9) Ostrow, C. L. (1997) Use of Trendelenburg position by critical care nurses: Trendelenburg Survey. American Journal of Critical Care; 6: 3, 172-6.

(10) Doering, L. (1993) The effect of positioning on hemodynamics and gas exchange in the critically ilk a review. American Journal of Critical Care; 2: 3, 208-16.

(11) Martin, J. (1995) The Trendelenburg position: a review of current slants about head down tilt. AANA Journal; 63: 1, 29-36.

(12) Winslow, E. (1995) Research for practice. American Journal of Nursing; 95: 7, 51.

Margaret Knowles, RCpN, is on the new graduate programme at Whakatane Hospital, working in a surgical ward. This article was developed from an assignment she wrote last year as a third-year nursing student at Waiariki Institute of Technology, Rotorua.