Severe Hemodilution - Clinical and Experimental Studies

Research output: ThesisDoctoral Thesis (compilation)

Abstract

In children, it is often desirable to minimize allogenic blood transfusion, and this thesis explores the physiology of an alternative method of managing perioperative blood loss: hemodilution with Ringer´s dextran.

Methods

Clinical studies: Arterial pressure, superior caval venous oxygen saturation (ScvO2) and blood lactate concentration (L) were studied during bone marrow harvesting (BMH) on 23 occasions in 19 children, 1-17 years of age, with healthy hearts and lungs.

Experimental studies - A. Shivering was induced by surface cooling and the hemodynamic and metabolic responses studied in hemodiluted (Hgb = circa 50 g/L), 12-14 weeks old anesthetized pigs and their normoemic controls. B. The tolerance to progressive isovolemic anemia was studied during hypothermia in anesthetized and paralyzed pigs (32 °C) and their normothermic controls (38.5 °C).

Main findings

Clinical studies: BMH caused a blood loss of 26 (17-42) ml per kg body weight, and decreased the blood hemoglobin concentration (Hgb) to 54 (47- 84) g/L. ScvO2 was 72 (61-88) % in the awake child, and increased to 82 (70 - 94) % after induction of general anesthesia. During hemodilution, it decreased to 76 (60-92) %. The lowest ScvO2: 66 (55-79) % was seen after awakening the child in spite of the fact that Hgb had now increased to 70 (58-95) g/L by transfusion of the child´s own, preoperatively collected, blood. There was an increase in mean heart rate from 89 to 108 bpm during BMH. Mean L increased from 1.0 to 1.5 mmol/L but was never above the normal limit.

Experimental studies: A. During shivering, oxygen consumption (VO2) increased by a mean factor of 2.9 in the hemodiluted pigs, and 3.7 in the controls (P< 0.001). Two of the former exhibited signs of myocardial hypoxia. B. Hgb at death was 14 ± 4 g/L in cooled pigs and 19 ± 3 g/L in the controls (P=0.015).

Clinical implications

-The healthy child tolerates extreme hemodilution (Hgb 50-70 g/L) if suitably anesthetized. The strain on the organism is greater after awakening.

-The findings cannot be extrapolated to children with compromised function of the heart or lungs, who the author believes will frequently benefit from a normal-high Hgb.

-Extreme hemodilution reduces oxygen delivery to the body and will, hence, decrease the tolerance to challenges with increased oxygen demand such as shivering.

-Cooling is modestly protective during severe anemia.

Details

Authors
  • Valéria Perez de Sá
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Anesthesiology and Intensive Care

Keywords

  • shivering, critical oxygen delivery, oxygen consumption, child, dextran, hypothermia, hemodilution, anemia, Anaesthesiology, intensive care, Anestesiologi, intensivvård, lactates
Original languageEnglish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
  • [unknown], [unknown], Supervisor, External person
Award date2002 Feb 8
Publisher
  • Valéria Perez de Sá, Kastanjegatan 46, Lund, 22456, Sweden,
Print ISBNs91-628-5104-7
Publication statusPublished - 2002
Publication categoryResearch

Bibliographic note

Defence details Date: 2002-02-08 Time: 13:15 Place: Segerfalkssalen, Wallenberg Neurocentrum External reviewer(s) Name: Lindahl, Sten Title: Professor Affiliation: Anestesi och Intensivvårdskliniken, Karolinska Sjukhuset, Stockholm --- Article: I.Perez de Sá V, Békássy A, Schou H, Werner M, Werner O.: Hemodilution During Bone Marrow Harvesting in Children. Anesth Analg 1991; 72:645-50. Article: II.Perez de Sá V, Békássy A, Schou H, Werner O.: Bone Marrow Harvesting in Children Managed without Allogenic Blood. Paediatric Anaesthesia 1994; 4:375-81. Article: III.Perez de Sá V, Cunha Goncalves D, Schou H, Jonmarker C, Werner O.: Hemodynamic and metabolic effects of shivering during acute normovolemic hemodilution in swine. Submitted for publication. Article: IV.Perez de Sá V, Roscher R, Cunha Goncalves D, Larsson A, Werner O.: Does Hypothermia Increase Tolerance to Severe Acute Normovolemic Anemia? Tentatively accepted for publication in Anesthesiology.