Fwd: [tacticalmedic] Hypothermia Increases Blood Loss During Surgery

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From: Fabrice Czarnecki <fczarnecki@...>

Date: 30 Dec 2007 17:00

Subject: [tacticalmedic] Hypothermia Increases Blood Loss During Surgery

tacticalmedic

This could be an important point for tactical medicine practitioners:

http://www.medpagetoday.com/Surgery/Anesthesiology/dh/7802

Hypothermia Increases Blood Loss During Surgery

By , North American Correspondent, MedPage Today

Published: December 27, 2007

Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine,

Harvard Medical School, Boston

CLEVELAND, Dec. 27 -- Less than a degree of hypothermia is enough to

significantly increase blood loss during surgery (P0.009), researchers here

said.

A meta-analysis of published studies shows that the same degree of

hypothermia is also enough to increase the need for transfusions

significantly (P0.027), according to Sessler, M.D., and colleagues at

the Cleveland Clinic.

The findings clarify an area of controversy, since studies of the

issue had given conflicting results, the researchers reported in the January

issue of Anesthesiology.

" When all the studies were evaluated together, the results clearly

show that even very mild hypothermia increases blood loss and transfusion

requirements by clinically important amounts, " Dr. Sessler said.

The data imply that -- except for special cases -- patients should be

maintained at a normal temperature during surgery, the researchers

concluded.

In a literature search, the researchers narrowed 1,800 studies down to

18 that met initial criteria; four were excluded for reporting problems. The

meta-analysis was thus based on 14 studies that met preset criteria for an

analysis of blood loss and 10 that met criteria for analysis of transfusion.

Studies were excluded if they were retrospective, if the core

temperature was reduced to less than 34° C, if local cooling methods had

been used, or if the sample size was smaller than 15.

All told, there were 1,219 patients in the blood loss studies and 985

in the transfusion studies.

The median of the mean temperatures reported for normothermic patients

in the 14 blood loss studies was 36.6° C, compared to 35.6° C in the

hypothermic patients.

The median temperature difference between normothermic and hypothermic

groups in the studies was 0.85° C.

Analysis found:

Normothermia was associated with significantly lower blood loss. The

estimated ratio of geometric means of total blood loss was 0.84, favoring a

normal temperature, with a 95% confidence interval from 0.74 to 0.96, which

was significant at P0.009.

Normothermia was also associated with a reduced need for transfusion.

The overall estimated relative risk was 0.78, with a 95% confidence interval

from 0.63 to 0.97, which was significant at P0.027.

In other words, the researchers said, even mild hypothermia of less

than 1° C increases blood loss by about 16% and the relative risk for

transfusion by about 22%.

Dr. Sessler and colleagues noted that hypothermia in the evaluated

studies was " of a magnitude that is typical for unwarmed surgical patients. "

They added that therapeutic hypothermia would probably produce greater

impairment of coagulation.

But Dr. Sessler said there are still situations where induced

hypothermia is necessary.

" In occasional patients, mostly those at risk for brain injury,

hypothermia is perfectly appropriate, " Dr. Sessler said. " In these patients,

physicians need to trade off the potential benefits and risks and choose the

optimal approach for each individual. "

The researchers cautioned that the study -- like all meta-analyses --

is subject to any flaws in the underlying studies. It may also be

confounded, they said, by publication bias.

They also cautioned that there are several instances of meta-analyses

being contradicted by large prospective randomized trials. In this case,

however, it is unlikely that a prospective randomized trial could be

conducted ethically, since keeping surgical patients at normal temperatures

has become the standard of care.

The study was supported by the NIH and the ph Drown

Foundation.

Dr. Sessler reported no conflicts.

Additional source: Anesthesiology

Source reference:

Rajagopalan S, et al " The effects of mild perioperative hypothermia on

blood loss and transfusion requirement " Anesthesiology 2008; 108: 71-7.

[Guest guest]

Hi all, this may be of interest to list members, sent a blank one by

mistake.

Regards to all and Happy new year to all,

---------- Forwarded message ----------

From: Fabrice Czarnecki <fczarnecki@...>

Date: 30 Dec 2007 17:00

Subject: [tacticalmedic] Hypothermia Increases Blood Loss During Surgery

tacticalmedic

This could be an important point for tactical medicine practitioners:

http://www.medpagetoday.com/Surgery/Anesthesiology/dh/7802

Hypothermia Increases Blood Loss During Surgery

By , North American Correspondent, MedPage Today

Published: December 27, 2007

Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine,

Harvard Medical School, Boston

CLEVELAND, Dec. 27 -- Less than a degree of hypothermia is enough to

significantly increase blood loss during surgery (P0.009), researchers here

said.

A meta-analysis of published studies shows that the same degree of

hypothermia is also enough to increase the need for transfusions

significantly (P0.027), according to Sessler, M.D., and colleagues at

the Cleveland Clinic.

The findings clarify an area of controversy, since studies of the

issue had given conflicting results, the researchers reported in the January

issue of Anesthesiology.

" When all the studies were evaluated together, the results clearly

show that even very mild hypothermia increases blood loss and transfusion

requirements by clinically important amounts, " Dr. Sessler said.

The data imply that -- except for special cases -- patients should be

maintained at a normal temperature during surgery, the researchers

concluded.

In a literature search, the researchers narrowed 1,800 studies down to

18 that met initial criteria; four were excluded for reporting problems. The

meta-analysis was thus based on 14 studies that met preset criteria for an

analysis of blood loss and 10 that met criteria for analysis of transfusion.

Studies were excluded if they were retrospective, if the core

temperature was reduced to less than 34° C, if local cooling methods had

been used, or if the sample size was smaller than 15.

All told, there were 1,219 patients in the blood loss studies and 985

in the transfusion studies.

The median of the mean temperatures reported for normothermic patients

in the 14 blood loss studies was 36.6° C, compared to 35.6° C in the

hypothermic patients.

The median temperature difference between normothermic and hypothermic

groups in the studies was 0.85° C.

Analysis found:

Normothermia was associated with significantly lower blood loss. The

estimated ratio of geometric means of total blood loss was 0.84, favoring a

normal temperature, with a 95% confidence interval from 0.74 to 0.96, which

was significant at P0.009.

Normothermia was also associated with a reduced need for transfusion.

The overall estimated relative risk was 0.78, with a 95% confidence interval

from 0.63 to 0.97, which was significant at P0.027.

In other words, the researchers said, even mild hypothermia of less

than 1° C increases blood loss by about 16% and the relative risk for

transfusion by about 22%.

Dr. Sessler and colleagues noted that hypothermia in the evaluated

studies was " of a magnitude that is typical for unwarmed surgical patients. "

They added that therapeutic hypothermia would probably produce greater

impairment of coagulation.

But Dr. Sessler said there are still situations where induced

hypothermia is necessary.

" In occasional patients, mostly those at risk for brain injury,

hypothermia is perfectly appropriate, " Dr. Sessler said. " In these patients,

physicians need to trade off the potential benefits and risks and choose the

optimal approach for each individual. "

The researchers cautioned that the study -- like all meta-analyses --

is subject to any flaws in the underlying studies. It may also be

confounded, they said, by publication bias.

They also cautioned that there are several instances of meta-analyses

being contradicted by large prospective randomized trials. In this case,

however, it is unlikely that a prospective randomized trial could be

conducted ethically, since keeping surgical patients at normal temperatures

has become the standard of care.

The study was supported by the NIH and the ph Drown

Foundation.

Dr. Sessler reported no conflicts.

Additional source: Anesthesiology

Source reference:

Rajagopalan S, et al " The effects of mild perioperative hypothermia on

blood loss and transfusion requirement " Anesthesiology 2008; 108: 71-7.