A comparison of central venous and arterial base deficit as a predictor of survival in acute trauma

Midline catheters for blood gas and acid/base monitoring in critical patients: A prospective observational study

Background:

Arterial lines and central venous catheter (CVC) allow to monitor patients’ acid-base status and gas exchange. Their placement and maintenance may however be burdened by severe complications. Midline Catheters (MC) are peripheral venous accesses that are less invasive and easier to insert compared to CVC and arterial lines.

Methods:

A prospective observational study was performed including stabilized critical patients with clinical indication to midline positioning before intensive care unit (ICU) discharge. The primary aim was to assess if venous sampling from MCs can be a reliable alternative to CVC for pH and CO2 monitoring. The secondary aim was to evaluate the correlation between samplings from MC, CVC and arterial line with regards to pH, carbon dioxide tension (pCO2), lactates and electrolytes. Three samples from CVC, arterial line and MC were collected simultaneously. Agreement and correlation of the studied parameters between different sampling sites were explored.

Results:

40 patients were included in the analysis. A good agreement for pH and pCO2 was recorded between MC and CVC: mean differences were 0.001 (95% CI −0.006 to 0.007) and 0.7 (−0.1 to 1.5), percentage error 0.4% and 11.2%, respectively. Correlation between MC and both central venous and arterial samples for pH, pCO2, lactates and electrolytes was found to be moderate-to-strong (Pearson’s R coefficient range 0.59–0.99, p < 0.001 for all these parameters).

Conclusions:

In stabilized critical patients, midline catheters represent a reliable alternative to CVC and arterial lines to monitor acid-base disturbances, CO2 levels and electrolytes. The present findings add to the known advantages of MC, which might be considered a first-line vascular access for non-critical or stabilized patients who do not require infusion of vesicant or irritant drugs.

Agreement between arterial and venous blood gases in trauma resuscitation in emergency department (AGREE)

INTRODUCTION

Arterial blood gas (ABG) sampling is routinely performed in major trauma patients to assess the severity of hemorrhagic shock. Compared to venous blood gas (VBG), ABG is an additional procedure with risks of hematoma and pain. We aim to determine if pH, base deficit (BD), and lactate from VBG and ABG in trauma patients are clinically equivalent. If proven, the need for ABG and its associated risks can be eliminated.

METHODS

This prospective observational study was conducted in the Emergency Department of National University Hospital, Singapore, between February and October 2016. We correlated paired ABG and VBG results in adult trauma patients. VBG and ABG were obtained within 10 min and processed within 5 min using a point-of-care blood gas analyzer. Bland-Altman plot analysis was used to evaluate the agreement between peripheral VBG and ABG in terms of pH, base deficit and lactate.

RESULTS

There were 102 patients included, with a median age of 34 (interquartile range 28-46) years and male predominance (90.2%). Majority of patients sustained blunt trauma (96.1%), and had injuries of Tier 1 and Tier 2 severity (60/102, 58.8%). Bland-Altman plot analyses demonstrated that only 72.6% of venous pH and 76.5% of venous BD lie within the pre-defined clinically acceptable limits of agreement, whereas 96.0% of venous lactate was within these limits.

CONCLUSION

Venous and arterial pH and BD are not within clinically acceptable limits of agreement, and ABG should be obtained for accurate acid-base status. However, venous lactate may be an acceptable substitute for arterial lactate.

Predicting arterial blood gas and lactate from central venous blood analysis in critically ill patients: a multicentre, prospective, diagnostic accuracy study

BACKGROUND

The estimation of arterial blood gas and lactate from central venous blood analysis and pulse oximetry [Formula: see text] readings has not yet been extensively validated.

METHODS

In this multicentre, prospective study performed in 590 patients with acute circulatory failure, we measured blood gases and lactate in simultaneous central venous and arterial blood samples at 6 h intervals during the first 24 h after insertion of central venous and arterial catheters. The study population was randomly divided in a 2:1 ratio into model derivation and validation sets. We derived predictive models of arterial pH, carbon dioxide partial pressure, oxygen saturation, and lactate, using clinical characteristics, [Formula: see text], and central venous blood gas values as predictors, and then tested their performance in the validation set.

RESULTS

In the validation set, the agreement intervals between predicted and actual values were -0.078/+0.084 units for arterial pH, -1.32/+1.36 kPa for arterial carbon dioxide partial pressure, -5.15/+4.47% for arterial oxygen saturation, and -1.07/+1.05 mmol litre(-1) for arterial lactate (i.e. around two times our predefined clinically tolerable intervals for all variables). This led to ∼5% (or less) of extreme-to-extreme misclassifications, thus giving our predictive models only marginal agreement. Thresholds of predicted variables (as determined from the derivation set) showed high predictive values (consistently >94%), to exclude abnormal arterial values in the validation set.

CONCLUSIONS

Using clinical characteristics, [Formula: see text], and central venous blood analysis, we predicted arterial blood gas and lactate values with marginal accuracy in patients with circulatory failure. Further studies are required to establish whether the developed models can be used with acceptable safety.

Assessing Acid–Base Status in Circulatory Failure: Relationship Between Arterial and Peripheral Venous Blood Gas Measurements in Hypovolemic Shock

Background and Objectives:

In severe circulatory failure agreement between arterial and mixed venous or central venous values is poor; venous values are more reflective of tissue acid–base imbalance. No prior study has examined the relationship between peripheral venous blood gas (VBG) values and arterial blood gas (ABG) values in hemodynamic compromise. The objective of this study was to examine the correlation between hemodynamic parameters, specifically systolic blood pressure (SBP) and the arterial–peripheral venous (A-PV) difference for all commonly used acid–base parameters (pH, Pco 2, and bicarbonate).

Design, Setting, Participants, and Measurements:

Data were obtained prospectively from adult patients with trauma. When an ABG was obtained for clinical purposes, a VBG was drawn as soon as possible. Patients were excluded if the ABG and VBG were drawn >10 minutes apart.

Results:

The correlations between A-PV pH, A-PV Pco 2, and A-PV bicarbonate and SBP were not statistically significant ( P = .55, .17, and .09, respectively). Although patients with hypotension had a lower mean arterial and peripheral venous pH and bicarbonate compared to hemodynamically stable patients, mean A-PV differences for pH and Pco 2 were not statistically different ( P = .24 and .16, respectively) between hypotensive and normotensive groups.

Conclusions:

In hypovolemic shock, the peripheral VBG does not demonstrate a higher CO2 concentration and lower pH compared to arterial blood. Therefore, the peripheral VBG is not a surrogate for the tissue acid–base status in hypovolemic shock, likely due to peripheral vasoconstriction and central shunting of blood to essential organs. This contrasts with the selective venous respiratory acidosis previously demonstrated in central venous and mixed venous measurements in circulatory failure, which is more reflective of acid–base imbalance at the tissue level than arterial blood. Further work needs to be done to better define the relationship between ABG and both central and peripheral VBG values in various types of shock.

Clinical value of triage lactate in risk stratifying trauma patients using interval likelihood ratios

Emergency physicians face the challenge of rapidly identifying high-risk trauma patients. Lactate (LAC) is widely used as a surrogate of tissue hypoperfusion. However, clinically important values for LAC as a predictor of mortality are not well defined.

OBJECTIVES

1. To assess the value of triage LAC in predicting mortality after trauma. 2. To compute interval likelihood ratios (LR) for LAC.

METHODS

Retrospective chart review of trauma patients with a significant injury mechanism that warranted labs at an urban trauma center.

OUTCOME

In-hospital mortality. Data are presented as median and quartiles or percentages with 95% confidence intervals. Groups (lived vs. died) were compared with Man-Whitney-U or Fisher's-exact test. Multivariate analysis was used to measure the association of the independent variables and mortality. The interval likelihood ratios were calculated for all LAC observed values.

RESULTS

10,575 patients; median age: 38 [25-57]; 69% male; 76% blunt; 1.1% [n=119] mortality. LAC was statistically different between groups in univariate (2.3 [1.6,3.0] vs 2.8 [1.6,4.8], p=0.008) and multivariate analyses (odds ratio: 1.14 [1.08-1.21], p=0.0001). Interval ratios for LR- ranged from 0.6-1.0. Increasing LAC increased LR+. However, LR+ for LAC reached 5 with LAC>9mmol/L and passed 10 (moderate and conclusive increase in disease probability, respectively) with LAC>18mmol/L.

CONCLUSIONS

In a cohort of trauma patients with a wide spectrum of characteristics triage LAC was statistically able to identify patients at high risk of mortality. However, clinically meaningful contribution to decision-making occurred only at LAC>9. LAC was not useful at excluding those with a low risk of mortality.

Low values of central venous oxygen saturation (ScvO2) during surgery and anastomotic leak of abdominal trauma patients

Background

There is a well known relationship between hypoperfusion and postoperative complications like anastomotic leak. No studies have been done addressing this relationship in the context of abdominal trauma surgery. Central venous oxygen saturation is an important hypoperfusion marker of potential use in abdominal trauma surgery for identifying the risk of anastomotic leak development. The purpose of this study was to identify the relationship between low values of central venous oxygen saturation and anastomotic leak of gastrointestinal sutures in the postoperative period in abdominal trauma surgery.

Methods

A cross-sectional prospective study was performed. Patients over 14 years old who required surgical gastrointestinal repair secondary to abdominal trauma were included. Anastomotic leak diagnosis was confirmed through clinical manifestations and diagnostic images or secondary surgery when needed. Central venous oxygen blood saturation was measured at the beginning of surgery through a central catheter. Demographic data, trauma mechanism, anatomic site of trauma, hemoglobin levels, abdominal trauma index, and comorbidities were assessed as secondary variables.

Results

Patients who developed anastomotic leak showed lower mean central venous oxygen saturation levels (60.0% ± 2.94%) than those who did not (69.89% ± 7.21%) (p = 0.010).

Conclusions

Central venous oxygen saturation <65% was associated with the development of gastrointestinal leak during postoperative time of patients who underwent surgery secondary to abdominal trauma.

Can venous base excess replace arterial base excess as a marker of early shock and a predictor of survival in trauma?

INTRODUCTION

Arterial base excess is an established marker of shock and predictor of survival in trauma patients. However, venous blood is more quickly and easily obtained. This study aimed to determine if venous base excess could replace arterial base excess as a marker in trauma patients at presentation and if venous base excess is predictive of survival at 24 hours and one week.

METHODS

This was a prospective study of 394 trauma patients presenting to the emergency department of a tertiary hospital over a 17-month period. Data on base excess at presentation, vital signs, shock index (SI), injury severity score (ISS), and mortality at 24 hours and one week was collected and analysed.

RESULTS

Arterial and venous blood gas tests were performed on 260 and 134 patients, respectively. Patients were stratified into groups based on their SI and ISS for analysis. There was no statistical difference between mean venous blood gas and arterial blood gas levels at presentation when SI > 0.7, regardless of ISS (p > 0.05). The mortality rate was 4.57%. Both venous and arterial base excess was lower in nonsurvivors compared to survivors (p < 0.05). However, at 24 hours and one week, the difference in base excess values at presentation between survivors and nonsurvivors was greater when using venous base excess compared to arterial base excess (11.53 vs. 4.28 and 11.41 vs. 2.66, respectively).

CONCLUSION

In conclusion, venous base excess can replace arterial base excess in trauma patients as a means of identifying and prognosticating early shock.

Correlation of Venous Blood Gas and Pulse Oximetry With Arterial Blood Gas in the Undifferentiated Critically Ill Patient

RATIONALE

Blood gas analysis is often used to assess acid-base, ventilation, and oxygenation status in critically ill patients. Although arterial blood gas (ABG) analysis remains the gold standard, venous blood gas (VBG) analysis has been shown to correlate with ABG analysis and has been proposed as a safer less invasive alternative to ABG analysis.

OBJECTIVE

The purpose of this study was to evaluate the correlation of VBG analysis plus pulse oximetry (SpO₂) with ABG analysis.

METHODS

We performed a prospective cohort study of patients in the emergency department (ED) and intensive care unit (ICU) at a single academic tertiary referral center. Patients were eligible for enrollment if the treating physician ordered an ABG. Statistical analysis of VBG, SpO₂, and ABG data was done using paired t test, Pearson χ², and Pearson correlation.

MAIN RESULTS

There were 156 patients enrolled, and 129 patients completed the study. Of the patients completing the study, 53 (41.1%) were in the ED, 41 (31.8%) were in the medical ICU, and 35 (27.1%) were in the surgical ICU. The mean difference for pH between VBG and ABG was 0.03 (95% confidence interval: 0.03-0.04) with a Pearson correlation of 0.94. The mean difference for pCO₂ between VBG and ABG was 4.8 mm Hg (95% confidence interval: 3.7-6.0 mm Hg) with a Pearson correlation of 0.93. The SpO₂ correlated well with PaO₂ (the partial pressure of oxygen in arterial blood) as predicted by the standard oxygen-hemoglobin dissociation curve.

CONCLUSION

In this population of undifferentiated critically ill patients, pH and pCO₂ on VBG analysis correlated with pH and pCO₂ on ABG analysis. The SpO₂ correlated well with pO₂ on ABG analysis. The combination of VBG analysis plus SpO₂ provided accurate information on acid-base, ventilation, and oxygenation status for undifferentiated critically ill patients in the ED and ICU.

Comparison of normal saline, hypertonic saline albumin and terlipressin plus hypertonic saline albumin in an infant animal model of hypovolemic shock

Introduction

In series of cases and animal models suffering hemorrhagic shock, the use of vasopressors has shown potential benefits regarding hemodynamics and tissue perfusion. Terlipressin is an analogue of vasopressin with a longer half-life that can be administered by bolus injection. We have previously observed that hypertonic albumin improves resuscitation following controlled hemorrhage in piglets. The aim of the present study was to analyze whether the treatment with the combination of terlipressin and hypertonic albumin can produce better hemodynamic and tissular perfusion parameters than normal saline or hypertonic albumin alone at early stages of hemorrhagic shock in an infant animal model.

Methods

Experimental, randomized animal study including 39 2-to-3-month-old piglets. Thirty minutes after controlled 30 ml/kg bleed, pigs were randomized to receive either normal saline (NS) 30 ml/kg (n = 13), 5% albumin plus 3% hypertonic saline (AHS) 15 ml/kg (n = 13) or single bolus of terlipressin 15 μg/kg i.v. plus 5% albumin plus 3% hypertonic saline 15 ml/kg (TAHS) (n = 13) over 30 minutes. Global hemodynamic and tissular perfusion parameters were compared.

Results

After controlled bleed a significant decrease of blood pressure, cardiac index, central venous saturation, carotid and peripheral blood flow, brain saturation and an increase of heart rate, gastric PCO₂ and lactate was observed. After treatment no significant differences in most hemodynamic (cardiac index, mean arterial pressure) and perfusion parameters (lactate, gastric PCO₂, brain saturation, cutaneous blood flow) were observed between the three therapeutic groups. AHS and TAHS produced higher increase in stroke volume index and carotid blood flow than NS.

Conclusions

In this pediatric animal model of hypovolemic shock, albumin plus hypertonic saline with or without terlipressin achieved similar hemodynamics and perfusion parameters than twice the volume of NS. Addition of terlipressin did not produce better results than AHS.

Evaluation of gasometric parameters in trauma patients during mobile prehospital care

OBJECTIVE

To evaluate gasometric differences of severe trauma patients requiring intubation in prehospital care.

METHODS

Patients requiring airway management were submitted to collection of arterial blood samples at the beginning of pre-hospital care and at arrival at the Emergency Room. We analyzed: Glasgow Coma Scale, respiratory rate, arterial pH, arterial partial pressure of CO2 (PaCO2), arterial partial pressure of O2 (PaO2), base excess (BE), hemoglobin O2 saturation (SpO2) and the relation of PaO2 and inspired O2 (PaO2/FiO2).

RESULTS

There was statistical significance of the mean differences between the data collected at the site of the accident and at the entrance of the ER as for respiratory rate (p = 0.0181), Glasgow Coma Scale (p = 0.0084), PaO2 (p <0.0001) and SpO2 (p = 0.0018).

CONCLUSION

tracheal intubation changes the parameters PaO2 and SpO2. There was no difference in metabolic parameters (pH, bicarbonate and base excess). In the analysis of blood gas parameters between survivors and non-survivors there was statistical difference between PaO2, hemoglobin oxygen saturation and base excess.

Prospective correlation of arterial vs venous blood gas measurements in trauma patients

OBJECTIVE

The objective of this study is to assess if venous blood gas (VBG) results (pH and base excess [BE]) are numerically similar to arterial blood gas (ABG) in acutely ill trauma patients.

METHODS

We prospectively correlated paired ABG and VBG results (pH and BE) in adult trauma patients when ABG was clinically indicated. A priori consensus threshold of clinical equivalence was set at ± less than 0.05 pH units and ± less than 2 BE units. We hypothesized that ABG results could be predicted by VBG results using a regression equation, derived from 173 patients, and validated on 173 separate patients.

RESULTS

We analyzed 346 patients and found mean arterial pH of 7.39 and mean venous pH of 7.35 in the derivation set. Seventy-two percent of the paired sample pH values fell within the predefined consensus equivalence threshold of ± less than 0.05 pH units, whereas the 95% limits of agreement (LOAs) were twice as wide, at -0.10 to 0.11 pH units. Mean arterial BE was -2.2 and venous BE was -1.9. Eighty percent of the paired BE values fell within the predefined ± less than 2 BE units, whereas the 95% LOA were again more than twice as wide, at -4.4 to 3.9 BE units. Correlations between ABG and VBG were strong, at r(2) = 0.70 for pH and 0.75 for BE.

CONCLUSION

Although VBG results do correlate well with ABG results, only 72% to 80% of paired samples are clinically equivalent, and the 95% LOAs are unacceptably wide. Therefore, ABG samples should be obtained in acutely ill trauma patients if accurate acid-base status is required.

Diaspirin cross-linked hemoglobin infusion did not influence base deficit and lactic acid levels in two clinical trials of traumatic hemorrhagic shock patient resuscitation

BACKGROUND

Diaspirin cross-linked hemoglobin (DCLHb) has demonstrated a pressor effect that could adversely affect traumatic hemorrhagic shock patients through diminished perfusion to vital organs, causing base deficit (BD) and lactate abnormalities.

METHODS

Data from two parallel, multicenter traumatic hemorrhagic shock clinical trials from 17 US Emergency Departments and 27 European Union prehospital services using DCLHb, a hemoglobin-based resuscitation fluid.

RESULTS

In the 219 patients, the mean age was 37.3 years, 64% of the patients sustained a blunt injury, 48% received DCLHb resuscitation, and the overall 28-day mortality rate was 36.5%. BD data did not differ by treatment group (DCLHb vs. normal saline [NS]) at any time point. Study entry BD was higher in patients who died when compared with survivors in both studies (US: -14.7 vs. -9.3 and European Union: -11.1 vs. -4.1 mEq/L, p < 0.003) and at the first three time points after resuscitation. No differences in BD based on treatment group were observed in either those who survived or those who died from the hemorrhagic shock. US lactate data did not differ by treatment group (DCLHb vs. NS) at any time point. Study entry lactates were higher in US patients who ultimately died when compared with survivors (82.4 vs. 56.1 mmol/L, p < 0.003) and at all five postresuscitation time points. No lactate differences were observed between DCLHb and NS survivors or in those who died based on treatment group.

CONCLUSIONS

Although patients who died had more greatly altered perfusion than those who survived, DCLHb treatment of traumatic hemorrhagic shock patients was not associated with BD or lactate abnormalities that would indicate poor perfusion.

Determining the accuracy of base deficit in diagnosis of intra-abdominal injury in patients with blunt abdominal trauma

BACKGROUND

Blunt abdominal trauma is a leading cause of morbidity and mortality among all age groups. A multiplicity of diagnostic modalities exists to evaluate the abdomen. We sought to assess the diagnostic performance of base deficit (BD) in identifying intra-abdominal injury in patients with blunt abdominal trauma.

METHODS

A prospective, nonrandomized series of patients with blunt abdominal trauma admitted into the 2 emergency departments was investigated from September 2007 to September 2008. Arterial blood samples were analyzed. According to BD, the patients were divided into 2 groups: group 1 who had a BD of -6 or lower and group 2 who had a BD more than -6. Ultrasonography, computed tomographic scan, or laparotomy was performed to find intra-abdominal injury. Follow-up at 7 days by telephone interview was obtained on patients who were discharged.

RESULTS

A total of 400 patients were enrolled, with a mean (SD) age of 34.8 ± 17.1 years. Two hundred sixty-eight (67%) of them were male. Seventy-six (19%) of patients had a BD of -6 or lower. Sixty-eight (17%) of them showed to have intra-abdominal injury with a BD of approximately -8.7 ± 3.2, compared with patients without intra-abdominal injury, -0.4 ± 0.1. Patients with a BD of -6 or lower achieved more laparotomy and blood transfusion compared with patients with a BD more than -6. On receiver operating characteristic curve analysis, the cutoff point of -6 was obtained with sensitivity and specificity of 88.2% and 95.2% and with positive and negative predictive values of 79% and 97.5%, respectively. None of outpatients had abdominal problem in telephone follow-up.

CONCLUSIONS

These data show that the BD is an early available important indicator to identify intra-abdominal injury in patients with blunt abdominal trauma, as well as a high transfusion requirement.

Transfusion in trauma: why and how should we change our current practice?

PURPOSE OF REVIEW

Major trauma is often associated with hemorrhage and transfusion of blood and blood products, which are all associated with adverse clinical outcome. The aim of this review is to emphasize why bleeding and coagulation has to be monitored closely in trauma patients and to discuss the rationale behind modern and future transfusion strategies.

RECENT FINDINGS

Hemorrhage is a major cause of early death after trauma. Apart from the initial injuries, hemorrhage is significantly promoted by coagulopathy. Early identification of the underlying cause of hemorrhage with coagulation tests (routine and bedside) in conjunction with blood gas analysis allow early goal-directed treatment of coagulation disorders and anemia, thereby stopping bleeding and reducing transfusion requirements. These treatment options have to be adapted to the civilian and noncivilian sector. Transfusion of blood and its components is critical in the management of trauma hemorrhage, but is per se associated with adverse outcome. Decisions must weigh the potential benefits and harms.

SUMMARY

Future transfusion strategies are based on early and continuous assessment of the bleeding and coagulation status of trauma patients. This allows specific and goal-directed treatment, thereby optimizing the patient's coagulation status early, minimizing the patient's exposure to blood products, reducing costs and improving the patient's outcome.