仰臥位保持による心拍・呼吸の変化と自覚的苦痛

Changes of Respiration and Heart Rate in Relation to the Discomfort Originated in Fixed Supine Position

要旨

　仰臥位の保持による生体への影響を心拍・呼吸・自覚的苦痛に注目して調べた．健康な成人女子5名を対象とし畳の上で2時間同一の仰臥位を保持させた．この間連続的に心拍を測定し呼吸曲線を記録すると共に，仰臥保持に伴う苦痛を一定の基準に則って訴えさせた．心拍・呼吸の測定にはテレメータ装置を用い，被験者の仰臥位保持条件を乱さない為に室外で記録した．呼吸曲線から呼吸数を知る一方，曲線のリズムが乱れた特異呼吸に注目しその出現頻度を経時的に調べると共に，心電図R-R間隔から30分毎に2分間ずつその変動係数（CV）を求めた．仰臥保持時間の経過と共に苦痛の訴えはいずれの被験者でも次第に増加した．心拍数は仰臥保持後30分間は次第に減少し以後一定の安定した値となり苦痛の増大とは無関係であった．CVは仰臥保持により増大する傾向であった．呼吸数の変化は被験者毎に特性があり共通の変化傾向は認められなかった．しかし特異呼吸の出現はいずれの被験者においても時間経過と共に増大しこの様相は苦痛の訴えの数の変化と相関を示した．特異呼吸の出現即ち安定した呼吸の乱れを観察することは自覚的な苦痛の程度を客観的に知るよい手掛かりになると推測される．

Abstract

　The effects of keeping the same supine position for 2 hours on heart beats, respiraion and subjective discomfort were studied in 5 healthy female adults. Heart beats and respiration were observed continuously by telemetric method. Coefficient of variation of R-R interval (CV_R-R) was measured from the EEG recordings 5 times with 30 minutes interval during 2 hours. Irregular respiration that differed from the stable regular rhythmical pattern was investigated from respiratory recordings. The subjects were required to give a sigh to report perceived discomfort by predetermined forms which could be analyzed semiquantitatively. During the 2 hours of experiment the subjective discomfort of the person studied gradually increased. The heart rate gradually decreased during the first 30 minutes and maintained a stable rate during the rest of the period. CV_R-R tended to increase with time. Heart rate and respiration rate did not vary in relation to the discomfort perceived by the subjects. The irregular respiration distinguished from stable and rhythmical normal pattern was gradually increased with time and that correlates well with the degree of the discomfort complained. The frequency of irregular respiration may become a good objective index to estimate discomfort.