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

Catecholamines (Table 2)
During the induction phase of intraoperative hypothermia, core temperature, and mean arterial blood pressure decreased. As the core temperature fell to 32°C, plasma NE and EPI concentrations rose (p<0.05) to 685 ± 184 (662 ± 172) pg/ml and 563 ± 200 (506 ± 191) pg/ml, respectively, from basal preinduction concentrations (37°C) of 287 ±40 pg/ml and 50±15 pg/ml, respectively. However, with further cooling to 24°C, the NE and EPI values declined (p<0.05) to 442 ±12 (312 ±86) pg/ml and 174 ±78 (130 ± 62) pg/ml, respectively, which were not different from basal measurements. No significant differences in intraoperative plasma catecholamine concentrations were found between patients who had received preoperative nitrates alone versus those receiving nitrates plus beta blockers and/or calcium channel blockers. http://birthcontroltab.com/generic-plan-b-0-75mg.htmlThyroid Hormones (Table 3)
The absolute mean serum total T3 value decreased after the onset of bypass to 42 ± 5 ng/dl from a basal preinduction value of 61 ± 8 ng/dl (p<0.05). However, the T3 values corrected for hemodilution were not different either after bypass (69 ± 8) ng/dl or at hypothermic 24°C (63 ±8) ng/dl. During this same time interval of CABS and hypothermia, the FT3 and dialyzable fraction of T3 concentrations increased (p<0.05) from a basal mean value of 200 ±27 pg/dl and [3.2 ± .1] X 10—3, respectively, to 296 ±35 pg/dl and [8.2 ± 1.1] X 10 — 3 (Table 3). The dialyzable fraction of T3 remained elevated when measured again at 32°C, 28°C, and 24°C (p<0.05). Serum T4 corrected for hemodilution significantly increased to 8.8 ±0.9 jig/di when measured immediately after bypass (34.7°C) from a basal preinduction value of 7.1 ±.7 μg/dl. The FT4 and dialyzable T4 fraction increased dramatically from basal values of 2.8±.3 ng/dl and [.46± .05] X 10-3 to 7.2± 1.6 ng/dl and [1.3±.32] X 10 — 3, respectively, when they were measured immediately after bypass. These values remained elevated above basal values as the core temperature fell to 24°C (p<0.05).
Table 2—How the Induction of Hypothermia Altered Heart Rate, Blood Pressure and Plasma Catecholamine Concentrations

TimeSequence Preinduction Induction OnsetBypass Core Temp 32°C Core Temp 28°C Core Temp 24°C
Core Temp °C 37.0 ±0 36.1 ±.5* 34.7±.4* 31.5± .5* 27.8 ±.4* 24.1+ .2*
MAP, mm Hg 86±3 76 ±1* 70 ±4* 73 ±3* 60 ±3* 60 ±2*
HR, per min 57 ±3 64±8 69±6 63± 16
NE, pg/ml 287 ±40 387 ±113 550 ±102* 685 ±184* 709 ±167* 442 ±12
(360 ±94)t (416 ±83) (662 ±172)* (540+153) (312 ±86)
EPI, pg/ml 50± 15 28±9 159 ±55* 563 ± 200* 320 ±149* 174 + 78*
(29 ±8) (138 ±47) (506 ±191)* (267 ±136) (130 ±62)

Table 3—How the Induction of Hypothermia Altered Serum Thyroid Hormone Concentration and ACE Activity

TimeSequence Preinduction Induction OnsetBypass Core Temp 32°C Core Temp 28°C Core Temp 24°C
ACE, U/ml 14.4 ±1.9 13.3 ±1.8 15.1 ±3.0 9.0± 1.3 14.4 ±1.9 14.3 ±2.3
(14.5 ±1.8) (8.2 ±1.8)* (7.9 ±1.2)* (7.9 ±0.9)* (7.7 ±1.0)*
ALB, g/dl 3.5 ±.3 2.9± .2 2.2± .2 1.9± .04 1.9± .04 1.9 ± .1
Total T,, 61 ±8 61 ±5 69±8 49±6 62±6 63±8
ng/dl (55 ±5) (42 ±5)* (47 ±5)* (39 ±6)* (41 ±6)*
Free T3, 200 ±27 190 + 29 296 ±35* 303 ±59* 236 ±29 266 ±51
pg/dlt
Dialyzable 3.2± .1 3.5± .4 8.2 ±1.1* 7.0 ±.7* 7.4 ±.6* 7.6 ±.5*
fraction of
T,xl0-3t
Total T„ 7.1 ±.7 7.7±.8 8.8 ±.9* 6.2 ±.5 9.3 ±.7* 9.3 ±.8*
jig/dl (7.2 ±.7) (5.5 ±.6)* (5.6 ±.4) (6.1 ±.5)* (6.0 ±.4)*
Free T4, 2.8 ±.3 3.8± 1.2 7.2± 1.6* 5.4 ±1.4* 6.2 ±.8* 6.8± 1.5*
ng/dlt
Dialyzable .46 ±.05 .49 ±.08 1.3 ±.32* 1.0 ±.20* 1.04 ±.2* 1.1±.3*
fraction of
T4x 10 —3t
T/« 12±2 13 ± 1 13 ±3 15±2 21 ±2* 20 ±2*
FT/FT3t 16±2 18±2 24 ±4* 18 ±2 26 ±2* 24 ±2*

Category: Coronary Artery

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