軽症高血圧症における血圧高の把握—24時間血圧測定に対する安静時20分間血圧測定の意義

Determination of the blood pressure level in mild hypertension. :Significance of 20 minute resting blood pressure measurement comparing to 24 hour ambulatory blood pressure monitoring

　今日，軽症高血圧症に対して社会的関心が高まっているのは，（1）高血圧症の治療によって臓器障害が予防されることが明らかにされたこと^1〜5），（2）その効果は治療を早期に開始するほど大きいこと^6），そして，（3）多くの有用な薬物が開発され薬物療法が容易になったことなどが挙げられる。高血圧症の診断は血圧の測定によってなされるのが現状であり，したがって，血圧高を適切に把握することが高血圧ケアの第一歩であることには変わりない。高血圧の診断基準は種々示されているが^7,8），どのようにその患者を代表する血圧値をとらえるかについては今日でも統一された見解はない。血圧の日内変動については多くの研究があるが，一日の血圧変動の中で得られる無限の血圧値のいずれが患者の重症度，あるいは，予後と結びつくかについてはまだ十分に知られていない^9），また，24時間の血圧を測定するということは患者にとっても心理的，そして，肉体的負担が大きく，さらに，コストと効果の面についても今後詳細な検討が必要と思われる。

　今回は，未治療の高血圧患者について非観血的な方法による24時間の血圧測定を行い，同時に20分間の安静時血圧測定で得られた血圧値との相関について検討したので報告する

Determination of the blood pressure (BP) level in patients with mild hypertension (MHT) is quite dif-ficult, since ulcerations of BP are tremendously exag-gerated in the doctor's office. It has been well kno-wn that casual BP is less reliable to estimate LVH than BPs obtained at home or work-site. Although 24 hour ambulatory BP monitoring (ABPM) has been widely accepted to overcome this problems, it is still controversial whether this method is applicable to all hypertensive subjects with special regards to its cost and effect. Therefore, our study has dealt mainly with the development of more convenient and less expensive method to get reasonable BPs. Twenty two nonmedicated patients with MHT were selected for the study. After taking casual BP in the office, the resting 20 minute BP measurements at every 2 minute interval were performed with Dynamap 950. Ten BP values thus obtained were divided into two categorical phases ; early and late. The mean sys-tolic and diastoic pressures (Ps & Pd) in the early phase were significantly higher than those in the late phase. Beside mean Ps and Pd obtained from 24 hour ABPM, 4 categorical phases based on the time of a day were defined ; morning (from awaking to noon), afternoon (from noon to 6 pm), evening (from 6 pm to bed time) and night (during sleeping). Mutual correlation coefficients of these categorical BPs were calculated and compared to identify rea-sonably high significant correlations. The results revealed the highest BP at the office and the lowest one during sleeping. The office BPs closely resem-bled to the ones during afternoon period. On the other hand, mean Ps and Pd during 24 hour ABPM were similar to those at the early phase of resting 20 minute measurement. Although correlation coef-ficients obtained from the comparisons among office BPs and ones in all 24 hour categorical phases didnot reveal significantly high values, BPs obtained during early and late phases of 20 minute resting measurement revealed significantly high correation coefficients to all BPs obtained from 5 categorial phases of 24 hour ABPM. Especially the latter re-vealed higher values than the former. Thus we conclude that 20 minute consecutive BP measurement on initial hospital visit could give us invaluable in-formations comparable to those from 24 hour ABPM.