下肢の支持性が低下した人に対する移乗動作の身体的・心理的負担の評価

Abstract

背景 高齢化が進む中で人間の基本的な生活行動に看護支援が必要な人々が増加するとともに、看護者の腰痛も多発する状況にある。前報では、下肢の支持性が低下した人に対する移乗サポートロボットを用いての立ち上がり動作実験を行い、サポートを受ける人の身体負担が少ないロボットの動きについて検証を行った。その結果、深く前傾しロボットに伏臥して立ち上がる方法で筋疲労は比較的低く、胸部や腹部など身体に密着する側に改善を加えれば有効にロボット活用できる可能性が示唆された。研究目的 本研究では前報に引き続き、下肢の支持性が低下した人を対象とした移乗動作実験を行い、看護者が移乗動作をサポートする場合に、サポートを受ける側とサポートする側の両者にとって安全・安楽・自立を考慮した方法について検証することを目的とした。方法 1.対象および研究方法2004年10月、以下の実験および調査を実施した。被験者は、健康な平均的体格の20歳代の女子4名とした。実験は、看護現場で移乗方法として広く用いられている患者の両足の間に看護者の片足を入れて移乗する方法(「中足法」とする)と、前報で比較的有効な移乗サポートロボットであると検証されたロボットの動きに近い患者を前傾にして看護者の背部に乗せて移乗する方法(「背負い法」とする)を取り上げて移乗動作を行った。分析は、表面筋電図測定装置(SX230)を用いて各被験筋について筋積分値を算出して両者の比較を行った。また、同被験者に対して、安全・安楽・自立の観点から主観的反応調査を行った。2.倫理的配慮 対象は研究の趣旨に同意した者のみとし、研究参加に同意した後でも、いつでも辞退可能であること。また、プライバシーの保護についても文書と口頭で伝えた。結果 移乗サポートを受けた患者側の実験・調査結果をみると、中足法を用いた場合では、特に上肢に苦痛を感じており、動作時6秒間の筋積分値を比較しても上肢の筋活動が高いことが明らかとなった。一方、背負い法を用いた場合では、苦痛は比較的感じていないものの安全性・安心感・自立性の面では低値を示していた。また、移乗サポートを行った看護者側の結果では、中足法を用いた場合に腰部への負担が大きく、背負い法を用いた場合に上肢・下肢に負担が大きいことが認められた。結論 以上より、下肢の支持性が低下した人に対する移乗動作では、看護現場で広く行われている中足法はサポートを受ける側とサポートする側の両者において身体的負担は大きいものの、安全性・安心感・自立性の面からは有効であると考えられた。一方、背負い法では身体的負担は比較的低いものの、サポートを受ける患者側の安心感は低いことが明らかとなり、それぞれの移乗法の課題が示唆された。

Background Japan's population is graying rapidly. The increase in the number of people seeking assistance to carry out some of the basic everyday activities has resulted in an increased incidence of low back pain among nurses. In our previous study, electromyographic (EMG) activity in patients with reduced lower limb strength was measured during robot-assisted standing transfer in order to assess the usability of a robotic transfer aid in terms of user safety and comfort. The results of this previous study suggested that muscle fatigue associated with robot-assisted standing transfer can be reduced by allowing patients to bend their upper body forward over the robot before raising them to a standing position, and with a few modifications to the part of the robot which comes into contact with the user's chest and abdomen, the robot may have a potential to become a useful tool for assisting individuals in a standing transfer. Objective In the present study, EMG activity in patients with reduced lower limb strength was measured to identify the methods of transfer and lifting that are safe, secure, and convenient for both the provider and the receiver of support. Method 1. Subjects and Methods: The survey was conducted in October 2004. Subjects were four healthy women with average height and build aged in their 20s. The following transfer techniques were examined: 1) placing one leg between the legs of a patient in order to safely lift the patient to a standing position (Technique A), and 2) having a patient bend his/her body forward onto the nurse's back to lift him/her to a standing position (Technique B). Technique A is a customary lifting technique widely used by nurses in Japan, while-according to our previous study - Technique B proved to cause minimal patient discomfort. Muscle activity of the subjects was measured to compare the two lifting techniques. A surface electromyograph called SX230 was used to calculate the integral of the electromyogram signals (EMG integral) for each tested muscle. Subjects were interviewed regarding their perceived comfort and discomfort in terms of safety, sense of security, and convenience. 2. Ethical Consideration All subjects were fully informed of the purpose of the study before consenting to participate, and were fully aware that they could withdraw from the study at any time. They were also fully informed both orally and in writing about their right to privacy. Results Standing transfer using Technique A caused pain in the upper limb in the support receiver, with the EMG integral for the upper limb during the first 6 seconds of a standing transfer indicating relatively intense muscle activity. With Technique B, the support receiver experienced less pain but indicated an increased level of perceived discomfort in terms of safety, sense of security, and convenience. On the other hand, while Technique A caused the support giver much strain on the low back, Technique B inflicted excessive stress on both the upper and the lower limb muscles of the support giver. Conclusions The results obtained from the present study showed that both Techniques A and B have their merits and demerits. Technique A is a customary lifting technique which is widely used by nurses in Japan to raise individuals with reduced lower limb strength to a standing position. Although this technique inflicted relatively intense physical strain on both the support giver and the receiver, it gave the support receiver increased sense of safety and security. On the other hand, Technique B involved less physical strain but provided less sense of security to the support receiver.