Alterations in Sympathetic Nervous System Activity with Intraoperative Hypothermia during Coronary Artery Bypass Surgery: ACE

Alterations in Sympathetic Nervous System Activity with Intraoperative Hypothermia during Coronary Artery Bypass Surgery: ACEACE
The serum ACE activity, when corrected for hemodilution, was unchanged from a preinduction value of 14.4 ± 1.9 units/ml when measured at temperatures of 32°C and 24°C, 9.0 ± 1.3 units/ml and 14.3 ± 2.3 units/ ml, respectively.
Findings in Patients During Rewarming (Table 4). http://asthma-inhalers-online.com/buy-advair-diskus-inhaler.html
The mean time required for rewarming to 37°C was 38 ± 4 minutes, during which time the mean arterial blood pressure and heart rate increased in parallel with normalization of temperature. The plasma NE concentration increased to 736 ±110 pg/ml, at 35°C compared to a “basal” hypothermic (25°C) value of 442 ± 108 pg/ml (p<0.05). The plasma EPI value did not change between 25°C and 35°C (341 ± 115 pg/ml and 377 ±107 pg/ml, respectively). Neither serum ACE activity or T3 concentrations increased during the 38 ± 4 minutes of intraoperative rewarming.
The plasma NE concentrations measured four hours after surgery were higher than the “basal” (25°C) hypothermic value, 601 ± 149 pg/ml and 442 ± 108 pg/ ml, respectively. Two of the 11 patients received dobutamine in the ICU. The other nine patients received no catecholamine or other inotropic therapy. The two dobutamine-treated patients had plasma NE and EPI levels similar to other patients at this time-point. Serum T3 values were lower four hours postoperatively compared to a basal (25°C) hypothermic value, 61 ± 6 ng/dl and 75 ± 7 ng/dl, respectively. The serum ACE activity of 7.7 ± .5 units/ml was unchanged from basal hypothermic values of 8.1 ±.4 units/ml when measured four hours after surgery. However, the postoperative ACE activity of 7.7±.5 units/ml was lower than the preoperative mean value of 13.4 ± 1.7 units/ml.
Discussion
Catecholamine Findings

Marked elevations in plasma NE and EPI concentrations occurred in the patients during CABS and induced hypothermia, until the esophageal core temperature fell below 28°C. The plasma NE and EPI levels declined with further cooling to values at a temperature of 24°C which were not different from preoperative values. A similar trend was seen during the rewarming of patients from deep hypothermia. Their plasma NE levels did not show a significant increase during rewarming until their core temperature increased to 35°C.

Table 4—How Rewarming From Hypothermia Altered Heart Rate, Mean Arterial Blood Pressure, Plasma Catecholamine, and Thyroid Hormone and ACE Activity

Core Temp, °C 25.0± .2 27.0 ±.2* 29.1 ±.2* 31.0± .1* 33.2± .1* 35.1 ±.1* 37.0 ±.1* 34.5 ±.2* 35.9± .1*
Heart rate, 60 ±49 39±9 51 ±8 71 ±5 84 ±3* 93 ±4*
beats/min
MAP, mm Hg 69±5 77±4 72±3 69±4 68±3 63±2 64±3 83 + 4* 88 ±5*
Pump flow/cardiac 4.0 ±.2 4.2± .1 4.2± .1 4.3± .1 4.4 ±.2 4.4± .1 4.0± .3 6.0 ±.3* 6.4 ±.4*
output, L/min
NE, pg/ml 442 ±108 483 ±115 494± 110 661 ± 120 640 ±135 736 ±110* 701 ± 120* 370 ±86 601±149*
(247 ± 70)t (227 ±60) (338 ±75) (441 ±83) (482 ±108) (474 ±70) (428 ±70) (293 ±79)
EPI, pg/ml 341 ±115 334 ±98 303 ±44 434 ±102 282 ±60 377 ±107 386 ±108 166±55 458 ± 156
(189 ±58) (166 ±30) (198 ±46) (203 ±38) (180 ±55) (150 + 37) (256 ±108) (280 ±55)
ACE, U/ml 8.1 ±.4 8.0±.4 8.0± .5 8.4 ±.3 8.2±.4 8.8± .4 8.5± .5 7.8 ±.6 7.7± .5*
(5.4 ±.4) (5.3 ±.4) (5.3 ±.5) (5.9 ±.5) (5.7 ±.4) (5.7 ±.4) (5.7 ±.3) (7.4 ±.5)
Tj, ng/dl 75±7 71 ±6 69±5 70±7 70±7 70±6 71 ±6 59 ±4 61 ±6*
(50 ±4) (47 ±3) (49 ±3) (47 ±4) (50 ±6) (46 ±4) (45 ±3) (54 ±4)*
ALB, g/dl 1.8± .1 1.8 ± .1 1.8± .1 1.9± .1 1.8± .1 1.8± .1 1.7 ± .1 2.8 ±.2 Recovery Rm. 3.1 ± .2 ICU

Category: Coronary Artery

Tags: blood pressure, Coronary Artery Bypass Surgery, heart, hypothermia