Halothane 저혈압마취가 신장기능에 미치는 영향

Abstract

[한글]저혈압마취는 수술중 출혈을 감소시켜 수술시야를 좋게 하며, 대량의 출혈이 예상되는 수술에서 과다한 실혈(失血)을 감소시키고, 수술중 고혈압의 치료내지는 부작용을 예방하기 위하여 사용된다.

인위적인 저혈압 유도 방법은 Gardner (1946)에 의해 동맥절개법 (arterictomy)이 시도된 이래 여러가지가 소개되었는데, 근래에는 nitroprusside, trimethapen 및 halothane등 의 약물을 이용한 저혈압 유도법이 널리 사용되고 있다.

그러나 저혈압마취는 몇가지 위험성을 내포하고 있는데, 그중에서도 vital organs의 순환장애와 이에 따른 저산소증이 가장 큰 위험이다. 일반적으로 수축기혈압이 60 mmHg이상일 때 조직으로의 산소공급에 이상이 없으며 (Rollason등, 1960 ; Eckenheff 등. 1963), 말초저항을 극복하는데 필요한 최저 수축기혈압은 32 mmHg라고 알려져 있다 (Griffiths등 1948). 최근 정등( 1974 )은 개에서 halothane을 사용하여 수축기혈압을 60 mmHg와 30 mmHg로 하강시켰을 때 뇌조직으로의 산소공급에 특별한 지장이 없음을 보고한 바 있다. 본

실험은 저혈압마취가 신기능에 미치는 영향에 대한 연구로서 체중 10∼ 12Kg의 건강한 개를 60 mmHg로 하강시켜 30분간 유지시키다가 곧 이어서 30 mmHg로 내려 다시 30분간 유지시킨 후 회복시의 신혈류역학 및 제반 신기능 검사를 100분동안 조사하여 다음과 같은 결과를 얻었다.

(1) 수축기혈압은 halothane 흡입 중단 80분 후에 거외 완전히 마취전의 값으로 회복되었다.

(2) 신혈장류량 (P, A, H.제거율) 과 사구체여과율 (inulin제거율)은 halothane흡입 중단 100분후에도 각각 대조치의 63%와 74% 정도밖에 회복되지 않았다.

(3) 뇨량, 뇨농축등 (U/P osm 및 T**c^^H20 ), 그리고 Na, K, 삼투질 및 물의 배설율(FE^^Na, FE^^K, FE^^osm, FE^^H20 )은 마취중단 100분 후에 거의 완전히 대조치로 회복됨을 관찰 할 수 있었다.

이장의 결과로 미루어 보아 개에서 수축기혈압 60 mmHg와 30 mmHg에서 각각 30분동안 유지하였다가 회복시킬 경우, 전신혈류역학은 빨리 회복되지만 신혈류역학은 그 회복이 늦으며 여려가지 신기능은 거의 회복됨을 알 수 있는데 이러한 사실은 저혈압마취에 의하여 신장조직이 손상을 받지 않음을 나타내며 따라서 저혈압마취시 신조직의 산소공급에는 큰 지장을 받지 않았음을 추정할 수 있겠다.

[영문]Hypotensive anesthesia is widely used in an operation since: 1) it minimizes bleeding and provides a good operation field, 2) it prevents massive hemorrhage in an operation which otherwise involves a large amount of blood loss and 3) it is useful in an operation for hypertensive patients.

This procedure also involves a number of risks such as delayed awakening, reactionary bleeding, decrease in urine output and tissue hypoxia. The most dangerous complication can be hypoxia especially in the vital organs. It is therefore necessary to treat dehydraton or blood loss before hypotensive anesthesia

is induced.

Since hypotensive anesthesia was introduced by Gardner (1946) for an operation of olfactory groove meningioma, various methods of deliberate hypotension have been developed. The most common method of hypotensive anesthesia in the present day is to use drugs, such as trimethapen nitroprusside and halothane. The effect of hypotensive anesthesia on various physiological functions of animals have been investigated in the past. Griffiths and Gillies (1948) reported that, in the hypotension induced by sympathectomy, an arterial systolic pressure of 32 mmHg is the minimum to overcome peripheral resistance. Chung (1974) observed in the halothane-induced hypotensive dog that a systolic pressure of 30 mmHg wes requined to assure adequate cerebral oxygenation.

In the present study we have investigated the effect of halothane-induced hypotension on the renal function of dogs. The arterial systotlic pressure was succossively reduced to 60 and then to 30 mmHg for 30 min. each, and changes in various renal functions were studied during 100 min. of the recovery period.

The results are summarized as follows :

1. The systolic blood pressure completely recovered 80 min. after the cessation of halothane inhalation.

2. Average renal blood flow (estimated by (C)**PAH) and glomerular filtration rate (estimated by (C)**In) during the first 20 min. of the recovery phase were 25% and 45% of the control level. However after 100 min. of the recovery period, renal blood flow recovered to 63% and glomerular filtration rate to 74% of the control level.

3. Average urine flow during the first 20 min. of the recovery phase was approximately 40% of the control.

4. U/P osm. ratio was reduced to 90% of the control level during the first 20 min. of recovery, but it exceeded the control value after 20 min. of recovery.

5. T**c^^H20 was only 24% of the control value in the first 20 min. of recovery phase, but thereafter it gradually returned to the control level.

6. FE^^Na (fractional excretion of Na) was not significantly changed by halothane inhalation although there was a tendency to slight reduction at the beginning of the recovery phase.

7. FE^^K was 47% of the control value during the initial phase of recovery, but it returned to the control level after 40 min. of the recovery period.

8. FE^^osm and FE^^H20 were reduced to 56% and 50% of the control level after the hypotensive period, but returned to 70% and 82% of the control level after 40 min. of the recovery period.

These results indicate that although the systemic blood pressure completely recovered after halothane-induced hypotension, renal hemodynamics are not completely recovered within 100 min. of the recovery period. However renal functions are mostly reversible, suggesting that halothane-induced hypotension did not induce irreversible damage of renal tissue.