Coagulopathy after a liver resection: is it over diagnosed and over treated?

BACKGROUND

Prothrombin time-international normalized ratio (PT-INR) is widely utilized to guide plasma therapy and initiation of thromboprophylaxis after a hepatectomy. Thrombelastography (TEG) monitors shear elasticity, which is sensitive to cellular and plasma components in blood, allowing for functional assessment of the life of the clot. The objective of this study was to prospectively compare PT-INR and TEG in liver resection patients.

METHODS

Forty patients were enrolled before undergoing an elective hepatectomy. Patients underwent a liver resection utilizing a low central venous pressure (CVP) anaesthetic technique and intermittent Pringle manoeuver. PT-INR and TEG were drawn prior to incision, post-operatively, and post-operative days 1, 3 and 5.

RESULTS

All post-operative PT-INR values increased significantly when compared with pre-operative PT-INR (P < 0.01). The time of onset to clot (R-value) decreased significantly at the post-operative time point (P = 0.04), consistent with a relative hypercoagulability. Subsequent R-values were not different compared with the pre-operative R-value. The strength of the clot (maximum amplitude, MA) was unchanged when comparing pre- and post-operative time points.

DISCUSSION

In spite of an elevation in PT-INR, patients undergoing a liver resection demonstrated a brief hypercoagulable state, followed by normal coagulation function based on TEG. These data call into question the practice of utilizing PT-INR to guide plasma transfusion and timing of prophylactic anticoagulation after a liver resection.

Incidence of deep vein thrombosis is increased with 30 mg twice daily dosing of enoxaparin compared with 40 mg daily

BACKGROUND

The purpose of this study was to analyze whether 2 standard dosing regimens of enoxaparin (30 mg twice daily vs 40 mg once daily) would result in different deep vein thrombosis (DVT) rates and anti-factor Xa activity (anti-Xa) in surgical patients.

METHODS

Patients who required enoxaparin for prophylaxis were followed prospectively. Demographics were recorded. Patients underwent standardized duplex screening. Peak anti-Xa levels were drawn on 4 consecutive days.

RESULTS

Sixty-three patients were followed up (28 patients on 30 mg twice daily, 35 patients on 40 mg once daily). There was no significant difference in demographics between groups. Twenty-five percent of patients on 30 mg twice daily developed a DVT, whereas 2.9% of patients on 40 mg once daily developed a DVT. Patients on 30 mg twice daily had significantly lower anti-Xa levels.

CONCLUSIONS

The incidence of DVT is increased in surgical patients who receive 30 mg twice daily dosing of enoxaparin compared with 40 mg daily. Dosing of 40 mg once daily results in significantly higher peak anti-Xa levels compared with 30 mg twice daily.

Trauma induces a hypercoagulable state that is resistant to hypothermia as measured by thrombelastogram

BACKGROUND

The aim of this study was to test the hypothesis that severely injured trauma patients would be hypercoagulable compared with controls measured by thromboelastography and that this hypercoagulability would persist over a broad range of temperatures.

METHODS

A prospective study evaluating the effects of temperature on coagulation in trauma patients with Injury Severity Scores ≥ 15 and controls was completed. Thromboelastography was performed 24 hours after admission at 4 temperatures ranging from 32°C to 38°C.

RESULTS

Ninety-two subjects (46 patients) were analyzed. Patients had a median Injury Severity Score of 20 (interquartile range, 16–26). Time to clot formation increased (P < .001) and fibrin cross-linking decreased (P < .01) in both groups as temperature decreased. Between groups, time to clot formation, fibrin cross-linking, and clot strength were significantly different at each temperature (P < .01), with patients being more hypercoagulable. Time to clot formation and fibrin cross-linking were more affected by temperature in controls compared with patients (P < .02).

CONCLUSIONS

Severely injured patients are more hypercoagulable than controls throughout a broad range of temperature. Decreasing temperature has a greater effect on coagulation in controls compared with patients.

Use of leukoreduced blood does not reduce infection, organ failure, or mortality following trauma

Background

Leukoreduced (LR) blood has been demonstrated to reduce morbidity and mortality in high-risk surgical patients, but not in trauma patients. The objective of the present study was to determine the effect of LR blood on morbidity and mortality. We hypothesized that the use of LR blood does not improve outcome in trauma patients.

Methods

This study was a retrospective cohort analysis of trauma patients transfused at a level 1 Trauma Center from 2001 to 2004. Between 2002 and 2003, LR blood was transfused. Prior to that time and subsequent to it, non-leukoreduced (NLR) blood was transfused. This created two historical comparison groups. Data collected included patient demographics, units of blood transfused, intensive care unit (ICU) and hospital days, ventilator days, injury severity score (ISS), mortality, presence of acute respiratory distress syndrome (ARDS), and infectious complications. A multiple organ dysfunction syndrome (MODS) score was calculated.

Results

The distribution of patients was as follows: 284 patients received only NLR blood, 153 received only LR blood, and 58 received at least one unit of each. The mean ISS was similar (NLR: 26, LR: 24; P > 0.1). No differences were seen between groups in units transfused (6.2 vs. 5.5), number of ICU days (8.2 vs. 9.0), number of hospital days (16.9 vs. 18.6), number of ventilator days (6.1 vs. 5.7), incidence of ARDS (8.3% vs. 8.5%), MODS score (5.5 vs. 5.9), mortality rate (15.1% vs. 15.7%), or infection rate (36% vs. 30%) (P > 0.1).

Conclusions

This study represents the largest series comparing trauma patients who received either LR or standard blood transfusions. The use of LR blood does not improve outcome in trauma patients.

A highly porous silica and chitosan-based hemostatic dressing is superior in controlling hemorrhage in a severe groin injury model in swine

BACKGROUND

This study compared the efficacy of 3 hemostatic dressings in a severe groin injury model in swine.

METHODS

Twenty-three swine received TraumaStat (OreMedix, Lebanon, OR), Chitoflex (HemCon, Inc., Portland, OR), or standard gauze for hemostasis. Complete femoral vessel transections were followed by 30 seconds of uncontrolled hemorrhage. The groin was packed with the randomized dressing followed by 30 seconds of compression. Resuscitation with lactated Ringer's solution commenced immediately postcompression to the preinjury mean arterial blood pressure. Hemostasis failure was defined as blood pooling outside the wound. Animals were monitored and maintained at the preinjury mean arterial pressure for 120 minutes, culminating with euthanization.

RESULTS

There were no differences in baseline values between groups. TraumaStat resulted in less hemostasis failure (P < .05), decreased postcompression blood loss (P < .05), and decreased fluid requirement (P < .05). No significant difference in mortality was seen between groups. There were no differences between standard gauze and Chitoflex with respect to dressing failure, posttreatment blood loss, or fluid resuscitation.

CONCLUSIONS

TraumaStat performed significantly better than Chitoflex and standard gauze in controlling hemorrhage from a severe groin injury in swine.

Resuscitation of haemorrhagic shock with normal saline vs. lactated Ringer's: effects on oxygenation, extravascular lung water and haemodynamics

Introduction

Pulmonary oedema and impairment of oxygenation are reported as common consequences of haemorrhagic shock and resuscitation (HSR). Surprisingly, there is little information in the literature examining differences in crystalloid type during the early phase of HSR regarding the development of pulmonary oedema, the impact on oxygenation and the haemodynamic response. These experiments were designed to determine if differences exist because of crystalloid fluid type in the development of oedema, the impact on oxygenation and the haemodynamic response to fluid administration in early HSR.

Methods

Twenty anaesthetised swine underwent a grade V liver injury and bled without resuscitation for 30 minutes. The animals were randomised to receive, in a blinded fashion, either normal saline (NS; n = 10) or lactated Ringer's solution (LR; n = 10). They were then resuscitated with study fluid to, and maintained at, the preinjury mean arterial pressure (MAP) for 90 minutes.

Results

Extravascular lung water index (EVLWI) began to increase immediately with resuscitation with both fluid types, increasing earlier and to a greater degree with NS. A 1 ml/kg increase in EVLWI from baseline occurred after administartion of (mean ± standard error of the mean) 68.6 ± 5.2 ml/kg of normal saline and 81.3 ± 8.7 ml/kg of LR (P = 0.027). After 150 ml/kg of fluid, EVLWI increased from 9.5 ± 0.3 ml/kg to 11.4 ± 0.3 ml/kg NS and from 9.3 ± 0.2 ml/kg to 10.8 ± 0.3 ml/kg LR (P = 0.035). Despite this, oxygenation was not significantly impacted (Delta partial pressure of arterial oxygen (PaO₂)/fraction of inspired oxygen (FiO₂) ≤ 100) until approximately 250 ml/kg of either fluid had been administered. Animals resuscitated with NS were more acidaemic (with lower lactates), pH 7.17 ± 0.03 NS vs. 7.41 ± 0.02 LR (P < 0.001).

Conclusions

This study suggests that early resuscitation of haemorrhagic shock with NS or LR has little impact on oxygenation when resuscitation volume is less than 250 ml/kg. LR has more favourable effects than NS on EVLWI, pH and blood pressure but not on oxygenation.

A novel highly porous silica and chitosan-based hemostatic dressing is superior to HemCon and gauze sponges

BACKGROUND

Hemostatic dressings have become increasingly popular as the optimal initial treatment for severe hemorrhage. The purpose of this study was to compare the hemostatic properties of a novel highly porous silica and chitosan-based dressing (TraumaStat) to HemCon, and gauze dressing in a severe groin injury model in swine.

METHODS

Thirty swine were blindly randomized to receive TraumaStat, HemCon, or standard gauze dressing for hemostatic control. A complex groin injury involving complete transaction of the femoral artery and vein was made. After 30 seconds of uncontrolled hemorrhage, the randomized dressing was applied and pressure was held for 5 minutes. Fluid resuscitation was initiated to achieve and maintain the baseline mean arterial pressure and the wound was inspected for bleeding. Failure of hemostasis was defined as pooling of blood outside of the wound. Animals were then monitored for 120 minutes and surviving animals were euthanized.

RESULTS

Blood loss before treatment was similar between groups (p > 0.1). TraumaStat had one failure, compared with five for gauze, and eight for HemCon (p = 0.005, TraumaStat vs. HemCon). TraumaStat significantly reduced median blood loss when compared with both HemCon and gauze (117 vs. 774 and 268 mL respectively, p < 0.05). At study conclusion, TraumaStat animals had a greater median hematocrit than both HemCon (24 vs. 19, p = 0.033), and gauze (24 vs. 19, p = 0.049) animals. Median volume of fluid resuscitation and mortality were not different between groups (p > 0.1).

CONCLUSIONS

TraumaStat was superior to HemCon and gauze dressings in controlling bleeding from a severe groin injury. TraumaStat may be a better hemostatic dressing for control of active hemorrhage than current standards of care.

A single bolus of 3% hypertonic saline with 6% dextran provides optimal initial resuscitation after uncontrolled hemorrhagic shock

BACKGROUND

The optimal fluid for early resuscitation of hemorrhagic shock would restore perfusion without increasing blood loss, hypothermia, acidosis, or coagulopathy. This study examined effects of a single bolus of hypertonic saline (HTS) with or without (+/-) dextran (D) after uncontrolled hemorrhage (UH) and determined optimal fluid composition.

METHODS

Fifty swine were anesthetized and underwent invasive line placement, celiotomy, splenectomy, suprapubic catheterization, and grade V liver injury. After 30 minutes of UH, blinded fluid resuscitation was initiated with a 250-mL bolus. Animals were randomized to five groups: normal saline (NS), 3% HTS (3%), 3% HTS/6% D (3% D), 7.5% HTS (7.5%), or 7.5% HTS/6% D (7.5% D). Mean arterial pressure (MAP) and tissue oxygen saturation (StO2) were recorded. Laboratory and thrombelastography (TEG) data were collected every 30 minutes. Animals were sacrificed 120 minutes after injury. Analysis of variance was used to compare groups. Significance was defined as p < 0.05.

RESULTS

Baseline characteristics and laboratory values were similar in all groups. All groups achieved a similar degree of shock. Two NS and two 3% animals did not survive to 120 minutes. Fluids containing dextran produced a significantly greater increase in MAP (p < 0.02). Animals receiving 3% D maintained a higher MAP 90 minutes after fluid bolus. Also, 7.5% +/- D produced a significantly greater initial increase in StO2 (p < 0.05). This effect declined after fluid bolus while 3% D continued to improve tissue oxygenation. Significant differences developed between groups in TEG values, hematocrit, fibrinogen, urine sodium, serum sodium, serum chloride, and urine output.

CONCLUSIONS

A single bolus of 3% D after uncontrolled hemorrhagic shock produces an adequate and sustained rise in MAP and StO2 and attenuates hypercoagulability. Resuscitation with 7.5% +/- D produces significantly increased urine output accompanied by a decline in MAP and StO2 over time. A single bolus of 7.5% D results in significant dilutional anemia and relative hypofibrinogenemia.

Resuscitation With Normal Saline (NS) vs. Lactated Ringers (LR) Modulates Hypercoagulability and Leads to Increased Blood Loss in an Uncontrolled Hemorrhagic Shock Swine Model

BACKGROUND

Lactated ringers (LR) and normal saline (NS) are used interchangeably in many trauma centers. The purpose of this study was to compare the effects of LR and NS on coagulation in an uncontrolled hemorrhagic swine model. We hypothesized resuscitation with LR would produce hypercoagulability.

METHODS

There were 20 anesthetized swine (35 +/- 3 kg) that underwent central venous and arterial catheterization, celiotomy, and splenectomy. After splenectomy blinded study fluid equal to 3 mL per gram of splenic weight was administered. A grade V liver injury was made and animals bled without resuscitation for 30 minutes. Animals were resuscitated with the respective study fluid to, and maintained, at the preinjury MAP until study end. Prothrombin Time (PT), Partial Thromboplastin Time (PTT), and fibrinogen were collected at baseline (0') and study end (120'). Thrombelastography was performed at 0'and postinjury at 30', 60', 90', and 120'.

RESULTS

There were no significant baseline group differences in R value, PT, PTT, and fibrinogen. There was no significant difference between baseline and 30 minutes R value with NS (p = 0.17). There was a significant R value reduction from baseline to 30 minutes with LR (p = 0.02). At 60 minutes, R value (p = 0.002) was shorter while alpha angle, maximum amplitude, and clotting index were higher (p < 0.05) in the LR versus the NS group. R value, PT, and PTT were significantly decreased at study end in the LR group compared with the NS group (p < 0.05). Overall blood loss was significantly higher in the NS versus LR group (p = 0.009).

CONCLUSIONS

This data indicates that resuscitation with LR leads to greater hypercoagulability and less blood loss than resuscitation with NS in uncontrolled hemorrhagic shock.

The utility of the Digi-walker step counter to assess daily physical activity patterns

PURPOSE

The Digi-Walker step counter is a promising and cost-effective tool to measure physical activity under free-living conditions. Two specific studies were conducted to evaluate the number of steps required to meet current physical activity guidelines.

METHODS

Thirty-one adults (17 men, 14 women) served as participants. In study 1, we determined the number of steps to complete a mile under two different conditions and three paces. In study 2, we conducted a field trial to examine the relationship between daily step counts and other indices of physical activity. Participants in this study wore a Digi-Walker for 2 consecutive weeks and completed the 7-d physical activity recall (PAR) after each week.

RESULTS

In study 1, there were no differences in step counts by site, but steps were inversely related to pace, with values ranging from 1330 to 1996. Individual step counts at a specific pace were negatively correlated with height, weight, leg length, and stride length and were positively correlated with body fatness. In study 2, participants had average daily step counts of 11,603 when structured vigorous activity was included and 8265 when only light and moderate activity were measured. Modest correlations were found between step counts and estimated energy expenditure. Similar correlations were observed when step counts were related to minutes of activity per day and minutes of sitting per day.

CONCLUSIONS

Pedometers provide a useful indicator of daily step counts but variability in activity patterns make it difficult to establish step count guidelines that correspond with other public health guidelines.