The traditional vs "1:1:1" approach debate on massive transfusion in trauma should not be treated as a dichotomy.

Traditional transfusion guidelines suggest that fresh frozen plasma (FFP) should be given based on laboratory or clinical evidence of coagulopathy or acute loss of 1 blood volume. This approach tends to result in a significant lag time between the first units of erythrocytes and FFP in trauma requiring massive transfusion. In severe trauma, observational studies have found an association between increased survival and aggressive use of FFP and platelets such that FFP:platelet:erythrocyte ratio approaches 1:1:1 to 2 from the first units of erythrocytes given. There are considerable concerns over either approach, and no randomized controlled trials have been published comparing the 2 approaches. Nowadays, trauma clinicans are incorporating the strenghts of both approaches and are no longer treating them as a dichotomy. Specifically, "1:1:1" proponents have devised 1:1:1 activation criteria to minimize unnecessary FFP and platelet transfusion and are prepared to deactivate the protocol as soon as patient is stabilized. Similarly, 1:1:1 skeptics are more mindful of the need to be proactive about trauma coagulopathy and the inherent delays in FFP administration in trauma patients.

Prevalence of survivor bias in observational studies on fresh frozen plasma:erythrocyte ratios in trauma requiring massive transfusion.

Observational studies on transfusion in trauma comparing high versus low plasma:erythrocyte ratio were prone to survivor bias because plasma administration typically started later than erythrocytes. Therefore, early deaths were categorized in the low plasma:erythrocyte group, whereas early survivors had a higher chance of receiving a higher ratio. When early deaths were excluded, however, a bias against higher ratio can be created. Survivor bias could be reduced by performing before-and-after studies or treating the plasma:erythrocyte ratio as a time-dependent covariate.We reviewed 26 studies on blood ratios in trauma. Fifteen of the studies were survivor bias-unlikely or biased against higher ratio; among them, 10 showed an association between higher ratio and improved survival, and five did not. Eleven studies that were judged survivor bias-prone favoring higher ratio suggested that a higher ratio was superior.Without randomized controlled trials controlling for survivor bias, the current available evidence supporting higher plasma:erythrocyte resuscitation is inconclusive.

Timing of tracheal intubation in traumatic cardiac tamponade: a word of caution.

Airway, breathing, and circulation are top priorities in any resuscitation. However, in cardiac tamponade, the decision to intubate the trachea and initiate positive pressure ventilation (PPV) should only be taken after consideration of the deleterious haemodynamic effects of positive intrathoracic pressure. We suggest that the threshold for intubation and PPV should be raised in tamponade and that intubation and PPV should, if possible, be timed so that relief of tamponade can immediately follow. In the trauma setting, emergency thoracotomy is the best approach. When intubation is unavoidable because of very low oxygen saturation or cardiac arrest, high ventilatory pressures should be avoided.

Choosing the correct laryngeal mask airway sizes and cuff inflation volumes in pediatric patients.

The laryngeal mask airway (LMA) is now standard airway management equipment in prehospital and Emergency Department (ED) care. Most providers may not be able to match the pediatric LMA sizes to the appropriate weights of pediatric patients. The exact inflation volumes are also difficult to memorize. To overcome this problem, we propose the following equations: Weight (kg) of patient = 2(2 x LMA), where LMA is the size; cuff inflation volume (mL) = 5 x LMA.

Are we giving enough coagulation factors during major trauma resuscitation?

Hemorrhage is a major cause of trauma deaths. Coagulopathy exacerbates hemorrhage and is commonly seen during major trauma resuscitation, suggesting that current practice of coagulation factor transfusion is inadequate. Reversal of coagulopathy involves normalization of body temperature, elimination of the causes of disseminated intravascular coagulation (DIC), and transfusion with fresh-frozen plasma (FFP), platelets, and cryoprecipitate. Transfusion should be guided by clinical factors and laboratory results. However, in major trauma, clinical signs may be obscured and various factors conspire to make it difficult to provide the best transfusion therapy. Existing empiric transfusion strategies for, and prevailing teachings on, FFP transfusion appear to be based on old studies involving elective patients transfused with whole blood and may not be applicable to trauma patients in the era of transfusion with packed red blood cells (PRBCs). Perpetuation of such concepts is in part responsible for the common finding of refractory coagulopathy in major trauma patients today. In this review, we argue that coagulopathy can best be avoided or reversed when severe trauma victims are transfused with at least the equivalent of whole blood in a timely fashion.

Heliox vs air-oxygen mixtures for the treatment of patients with acute asthma: a systematic overview.

OBJECTIVE: To evaluate, by systematic review, the efficacy of heliox on respiratory mechanics and outcomes in patients with acute asthma. METHODS: The search strategy included searching electronic databases (MEDLINE, EMBASE, and The Cochrane Library) and the references of relevant articles. Study quality was assessed based on allocation concealment. Randomized controlled trials (RCTs) comparing heliox to an air-oxygen mixture (airO(2)) as an adjunct treatment in patients with acute asthmatic attacks were analyzed. For the qualitative portion of the analysis, all reports of the use of heliox in patients with acute asthma were included. RESULTS: Four RCTs (n = 278) were found to have a common respiratory parameter (peak expiratory flow rate as a percentage of predicted) suitable for meta-analysis. Within the 92% confidence interval (CI), there was a small benefit with the use of heliox compared to airO(2) (weighted mean difference, + 3%; 95% CI, - 2 to + 8%). There was also a slight improvement in the dyspnea index (weighted mean difference, 0.60; 95% CI, 0.04 to 1.16) with the use of heliox over airO(2). Overall, five RCTs, one nonrandomized unblinded parallel trial, one retrospective case-matched control trial, three case series, and one case report had results in favor of heliox; one RCT and one case series showed no improvement with heliox; one RCT showed a possible detrimental effect with heliox; and 1 small RCT was inconclusive. Most investigators did not prevent entrainment of room air during heliox use or compensate for the lower nebulizing efficiency of heliox. CONCLUSION: Based on surrogate markers, heliox may offer mild-to-moderate benefits in patients with acute asthma within the first hour of use, but its advantages become less apparent beyond 1 h, as most conventionally treated patients improve to similar levels, with or without it. The effect of heliox may be more pronounced in more severe cases. There are insufficient data on whether heliox can avert tracheal intubation, or change intensive care and hospital admission rates and duration, or mortality.

Use of heliox in critical upper airway obstruction. Physical and physiologic considerations in choosing the optimal helium:oxygen mix.

Heliox has a lower density than oxygen and nitrogen, and can improve ventilation rapidly in patients with critical upper airway obstruction. The choice of the best helium:oxygen ratio depends on whether the predominant problem is hypercarbia or hypoxia. In the former situation, 80% helium should be used, and in the latter, 100% oxygen is appropriate.

Estimating with confidence the risk of rare adverse events, including those with observed rates of zero.

Omission of a confidence interval (CI) associated with the risk of a serious complication can lead to inaccurate interpretation of risk data. The calculation of a CI for a risk or a single proportion typically uses the familiar Gaussian (normal) approximation. However, when the risk is small, "exact" methods or other special techniques should be used to avoid overshooting (risks that include values outside of [0,1]) and zero width interval degeneration. Computer programs and simple equations are available to construct CIs reasonably accurately. In the special case in which the complication has not occurred, the risk estimated with 95% confidence is no worse than 3/n, where n is the number of trials.

Fresh-frozen plasma transfusion strategy in trauma with massive and ongoing bleeding. Common (sense) and sensibility.

During trauma resuscitation involving massive transfusion, the best fresh-frozen plasma to packed red blood cells ratio is unknown. No randomised controlled trial (RCT) is available on this subject, although there are plenty of observational studies suggesting that the ratio should be about 1:1. This ratio also makes more physiological sense, and we suggest that in patients with massive and ongoing bleeding, it is a sensible strategy with which to start resuscitation.

A mathematical model for fresh frozen plasma transfusion strategies during major trauma resuscitation with ongoing hemorrhage.

BACKGROUND: Randomized controlled trials of how best to administer fresh frozen plasma (FFP) in the presence of ongoing severe traumatic hemorrhage are difficult to execute and have not been published. Meanwhile, coagulopathy remains a common occurrence during major trauma resuscitation and hemorrhage remains a major cause of traumatic deaths, suggesting that current coagulation factor replacement practices may be inadequate. METHODS: We used a pharmacokinetic model to simulate the dilutional component of coagulopathy during hemorrhage and compared different FFP transfusion strategies for the prevention or correction, or both, of dilutional coagulopathy. Assuming the rates of volume replacement and loss are roughly equal, we derived the hematocrit and plasma coagulation factor concentration over time based on the rate of blood loss and replacement, the hematocrit and coagulation factor concentration of the transfusate, and the hematocrit and plasma factor concentration at the time when FFP transfusion begins. RESULTS: Once excessive deficiency of factors has developed and bleeding is unabated, 1-1.5 units of FFP must be given for every unit of packed red blood cells (PRBC) transfused. If FFP transfusion should start before plasma factor concentration drops below 50% of normal, an FFP:PRBC transfusion ratio of 1:1 would prevent further dilution. CONCLUSION: During resuscitation of a patient who has undergone major trauma, the equivalent of whole-blood transfusion is required to correct or prevent dilutional coagulopathy.