Evidence matrix 1
Clinical question
In patients with critical bleeding requiring massive transfusion, what is the effect of variation of physiologic, biochemical and metabolic (including temperature) parameters on morbidity, mortality and transfusion rate?
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Evidence statement
Hypothermia, metabolic acidosis, thrombocytopenia and coagulopathy may be independently associated with increased mortality. 15,61,63-68
Evidence base
Consistency
Satisfactory (C): Some inconsistency reflecting genuine uncertainty around clinical question. Studies investigating:
Hypothermia: Consistency in definition of outcome. Similar direction of effect (i.e. hypothermia associated with poor survival), although some inconsistency in statistical significance, with three studies showing similar results and two studies in which temperature was not a significant predictor of mortality. pH: All five studies were consistent with regard to low pH/acidosis being significantly associated with poorer survival. The definition of the outcome and the threshold parameters for pH values were also consistent. Base deficit: Consistency in outcome definition. There was some inconsistency in direction of effect – three studies indicated an association between increased base deficit and poor survival, and two indicated that base deficit was not a significant predictor of mortality. INR: All four studies were consistent with regard to a higher international normalised ratio (INR) being associated with poor survival. The definition of the outcome and the threshold parameters for INR values were also consistent. Prothrombin time: N/A. One study included for this outcome. Partial thromboplastin time: Two studies identified were inconsistent with regard to the association between PTT and mortality. Platelet count: Three studies were inconsistent with regard to the association between low platelet count and mortality, primarily because different definitions were used. Clinical impact
Satisfactory (C): Moderate clinical impact. Studies investigating:
Hypothermia: Sample size was sufficiently large (ranged from n = 45 to n = 246). Three studies showed that reduced core body temperature was associated with increased mortality in patients who had critical bleeding and those who were transfused. Gonzalez et al (2007) 64 and Moore et al (2008) 68 showed that reduced body temperature was not significantly associated with mortality in patients who experienced shock resuscitation or haemorrhagic shock. pH: All five studies showed that reduced pH was associated with increased mortality in patients with critical bleeding and those who were transfused. Base deficit: Sample size was sufficiently large (ranged from n = 45 to n = 252). Three studies showed that an increase in base deficit was associated with an increased mortality in critically bleeding and transfused patients. Two studies showed base deficit was not significantly associated with mortality in patients who experience shock resuscitation or have haemorrhagic shock. INR: Sample size was sufficiently large (ranged from n = 97 to n = 247). All studies showed that an increase in INR was associated with increased mortality in critically bleeding and transfused patients. 15,61,64,68 Gonzalez and colleagues stratified analysis by admission to emergency department and admission to an intensive care unit.64 Prothrombin time: Small sample size (n = 45). Partial thromboplastin time: Two studies included are of limited clinical impact, each demonstrating different activated partial prothrombin time (APTT) parameters and statistical significance. Sample size is sufficient (n = 45 to n = 119). Platelet count: Three studies included; the largest study reporting on this outcome found that non-survivors had lower platelet counts. Sample size is sufficient with the included studies (n = 45 to n = 174). In all studies, consideration of adverse events was not applicable to this recommendation as the outcome is mortality. Generalisability
Good (B): Studies investigating:
Hypothermia: All participants in three studies were trauma patients and one study analysed shock resuscitation patients. All patients were critically bleeding. pH: Participants in four studies were trauma patients; one study analysed patients with haemorrhagic shock. Base deficit: Participants in three studies were trauma patients, 61,65,66 one study was on haemorrhagic shock patients 68 and one study on shock resuscitation patients. 64 All patients were critically bleeding. INR: Participants in two studies were trauma patients, 15,61 one haemorrhagic shock 68 and one study shock resuscitation patients. 64 Prothrombin time: One study included. Partial thromboplastin time: Small sample size and contradictory results for the two studies included. Platelet count: Contradictory results for all three studies included. There were no study design restrictions as all studies were case series; hence, patients were in natural environments when the outcome was measured. Applicability
Good (B): Studies investigating:
Hypothermia: Three United States based studies and one Australian based study. pH: Four United States based studies and one Australian based study. Base deficit: Five United States based studies. INR: Three United States based studies and one Australian based study. Prothrombin time: One United States based study. Partial thromboplastin time: One United States based and one Australian based study. Platelet count: Two United States based studies and one Australian based study. This evidence base is applicable to the Australian setting and there are no organisational or cultural barriers. |