저온법 및 체외순환법을 병용한 개심술시행시의 관류량(灌流量) 및 충전액(充塡液)결정에 관한 연구

Abstract

[한글]

Studies of Optimal Flow Fate and Priming Solution in Extracorporeal Circulation

Combined with Moderate Hypothermia and Hemodilution Technique

Sung-Nok Hong, M.D.

Department of surgery, Yonsei University College of medicine Seoul, Korea

(Directed by Drs, K.S. Min and P.W. Hong)

When adequate hypothermic perfusion combined with a total hemodilution technic is

used for cardiovascular surgery, several advantages over the conventional method

are offered. These are reduction of flow rate, simplification of the heart-lung

machine, economy in operation without need for large amount of fresh heparinized

blood and elimination of the complication of blood priming, i.e., homologou blood

syndrome, blood incomoatibility, serum hepatitis and sludging. There are many

reports of favorable clinical results using this combined technique(Zuhdi et. 1962;

Sealy et al., 1959). However, one of the still unsettled problems in this combined

approach is the flow rate which can meet the reduced oxygen demands of the

organism. Another controversial subject is the ideal type of non-hemic solution for

priming the machine. According to some authors, Ringer's lactate solution caused

the least over-all physiologic disturbance, including changes in blood volume,

acid-base balance, electrolyte concentration and hemolysis(Neville et al., 1966,

1967).

In the following studies, attempts were made to define the adequate flow rate in

cardiophlmonary bypass combined with moderate hypothermia and also to observe the

effect of perfusates on the acid-base eqauilibrium, which has been one of the

primery concerns since the combined bypass technic has been adopted.

Sixty cases with congenital or acquired heart disease were subjected to the open

cardiac repairs under cardio pulmonary bypass at Severance Hospital from Nov. of

196 through Sept. of 1967. The metabolic changes including oxygen consumption,

blood pH, CO^^2 tension and arterial oxygen saturation were observed in the last 40

cases consecutively.

Thirty patients on whom the data for this study was available were divided into

four groups according to the flow rate3 on total bypass and the types of priming

solution. Group Ⅰ, Ⅱ and Ⅲ were all primed rates in each groups were as follows;

less than 1,500ml./min/M**2 in Group Ⅰ, 1,500 to 1,800 ml./min./M**2 in Group Ⅱ,

more than 1,800 ml./min./M**2 in Group Ⅲ and an average of 1,669 ml./min./M**2 in

Group Ⅳ. Blood samples were obtained before anesthesia, 10 min., 20min., and

30min. after onset of total bypass, in the immediate postoperative period and 3

hours after termination of surgery and once a day for 5 to 7 days following

surgery.

A Zuhdi modification(1961) of the DeWall bubble oxygenator was used, with a

stainless steel coil incorporated into the helix for the purpose of blood stream

heat exchange. The flow rate was regulated manually during the bypass according to

the amount or venous return to the oxygenator and this tended to produce higher

flow rates than previously reported(Auh야 et al., 1964).

The results are summarized as follow:

1) Group Ⅰ perfused with a flow rate of less than 1,500ml./min./M**2 showed

evidence of mild hypoxia during hypass in terms of decreased oxygen consumption

below 50% of the control value, significant increase fo (A-V) O^^2 difference and

metabolic acidosis developing during and subsequent to bypass for 4 days.

2) In Group Ⅱ and Ⅲ whose flow sates were above 1,500ml./min./M**2(an average

flow fate o 1,664ml./min./M**2 in Group Ⅱ and 2,128 ml./min./M**2 in Group Ⅲ

respectively) the oxygen consumption rate on total bypass was more than 52% of the

preoperative value in Group Ⅱ and more than 73% in Group Ⅲ. There was also no

increase of (A-V)O^^2 difference on the bypass and the decreased arterial pH which

developed during perfusion was restored to normal range within the first

postoperative day in both groups. Accordingly the flow fates employed in Group Ⅱ

and Ⅲ were considered to satisfy the oxyfen needs of the tissue.

3) In Group Ⅳ, primed with Finger's lactate solution and perfused with and

average flow rate similar to Group Ⅱ, the arterial pH remained within normal limit

throughout the bypass and postoperative period despite a longer perfusion time than

the one of Group Ⅱ. This result was thought to be striking evidence of superiority

of Ringer's lactate solution as a priming solution to combat the metabolic acidosis

which tends to develop during and subsequent to low flow perfusion.

[영문]

When adequate hypothermic perfusion combined with a total hemodilution technic is used for cardiovascular surgery, several advantages over the conventional method are offered. These are reduction of flow rate, simplification of the heart-lung

machine, economy in operation without need for large amount of fresh heparinized blood and elimination of the complication of blood priming, i.e., homologou blood syndrome, blood incomoatibility, serum hepatitis and sludging. There are many reports of favorable clinical results using this combined technique(Zuhdi et. 1962; Sealy et al., 1959). However, one of the still unsettled problems in this combined approach is the flow rate which can meet the reduced oxygen demands of the

organism. Another controversial subject is the ideal type of non-hemic solution for priming the machine. According to some authors, Ringer's lactate solution caused the least over-all physiologic disturbance, including changes in blood volume,

acid-base balance, electrolyte concentration and hemolysis(Neville et al., 1966, 1967).

In the following studies, attempts were made to define the adequate flow rate in cardiophlmonary bypass combined with moderate hypothermia and also to observe the effect of perfusates on the acid-base eqauilibrium, which has been one of the

primery concerns since the combined bypass technic has been adopted.

Sixty cases with congenital or acquired heart disease were subjected to the open cardiac repairs under cardio pulmonary bypass at Severance Hospital from Nov. of 196 through Sept. of 1967. The metabolic changes including oxygen consumption,

blood pH, CO^^2 tension and arterial oxygen saturation were observed in the last 40 cases consecutively.

Thirty patients on whom the data for this study was available were divided into four groups according to the flow rate3 on total bypass and the types of priming solution. Group Ⅰ, Ⅱ and Ⅲ were all primed rates in each groups were as follows;

less than 1,500ml./min/M**2 in Group Ⅰ, 1,500 to 1,800 ml./min./M**2 in Group Ⅱ, more than 1,800 ml./min./M**2 in Group Ⅲ and an average of 1,669 ml./min./M**2 in Group Ⅳ. Blood samples were obtained before anesthesia, 10 min., 20min., and

30min. after onset of total bypass, in the immediate postoperative period and 3hours after termination of surgery and once a day for 5 to 7 days following surgery.

A Zuhdi modification(1961) of the DeWall bubble oxygenator was used, with a stainless steel coil incorporated into the helix for the purpose of blood stream heat exchange. The flow rate was regulated manually during the bypass according to the amount or venous return to the oxygenator and this tended to produce higher

flow rates than previously reported(Auh야 et al., 1964).

The results are summarized as follow:

1) Group Ⅰ perfused with a flow rate of less than 1,500ml./min./M**2 showed evidence of mild hypoxia during hypass in terms of decreased oxygen consumption below 50% of the control value, significant increase fo (A-V) O^^2 difference and metabolic acidosis developing during and subsequent to bypass for 4 days.

2) In Group Ⅱ and Ⅲ whose flow sates were above 1,500ml./min./M**2(an average flow fate o 1,664ml./min./M**2 in Group Ⅱ and 2,128 ml./min./M**2 in Group Ⅲ respectively) the oxygen consumption rate on total bypass was more than 52% of the

preoperative value in Group Ⅱ and more than 73% in Group Ⅲ. There was also no increase of (A-V)O^^2 difference on the bypass and the decreased arterial pH which developed during perfusion was restored to normal range within the first postoperative day in both groups. Accordingly the flow fates employed in Group Ⅱ

and Ⅲ were considered to satisfy the oxyfen needs of the tissue.

3) In Group Ⅳ, primed with Finger's lactate solution and perfused with and average flow rate similar to Group Ⅱ, the arterial pH remained within normal limit throughout the bypass and postoperative period despite a longer perfusion time than

the one of Group Ⅱ. This result was thought to be striking evidence of superiority of Ringer's lactate solution as a priming solution to combat the metabolic acidosis which tends to develop during and subsequent to low flow perfusion.