Cannulation Injury of the Radial Artery: Diagnosis and Treatment Algorithm

Pitfalls in the diagnosis and management of acid-base disorders in humans: a laboratory medicine perspective

Diagnostic errors affect patient management, and as blood gas analysis is mainly performed without the laboratory, users must be aware of the potential pitfalls. The aim was to provide a summary of common issues users should be aware of.A narrative review was performed using online databases such as PubMed, Google Scholar and reference lists of identified papers. Language was limited to English.Errors can be pre-analytical, analytical or post-analytical. Samples should be analysed within 15 min and kept at room temperature and taken at least 15-30 min after changes to inspired oxygen and ventilator settings, for accurate oxygen measurement. Plastic syringes are more oxygen permeable if chilled. Currently, analysers run arterial, venous, capillary and intraosseous samples, but variations in reference intervals may not be appreciated or reported. Analytical issues can arise from interference secondary to drugs, such as spurious hyperchloraemia with salicylate and hyperlactataemia with ethylene glycol, or pathology, such as spurious hypoxaemia with leucocytosis and alkalosis in hypoalbuminaemia. Interpretation is complicated by result adjustment, for example, temperature (alpha-stat adjustment may overestimate partial pressure of carbon dioxide (pCO2) in hypothermia, for example), and inappropriate reference intervals, for example, in pregnancy bicarbonate, and pCO2 ranges should be lowered.Lack of appreciation for patient-specific and circumstance-specific reference intervals, including extremes of age and altitude, and transformation of measurements to standard conditions can lead to inappropriate assumptions. It is vitally important for users to optimise specimen collection, appreciate the analytical methods and understand when reference intervals are applicable to their specimen type, clinical question or patient.

Procurement of Extended Vascularized Skin Flaps from the Donor Enables Hand Transplantation in Severe Upper Extremity Burns: An Anatomical Study

BACKGROUND

Hand transplantation in patients with severe upper extremity burns can be associated with an increased risk of exposure of vessels, tendons, and nerves because of extensive skin and soft-tissue deficit. This study evaluated how to reliably transfer additional extended skin flaps with a standard hand allograft.

METHODS

Twenty-five upper extremities were used. Sixteen were injected with latex to map the perforating branches of the brachial, superior ulnar collateral, radial, ulnar, and posterior interosseous arteries. Nine hand allografts were procured, injected with blue ink through the brachial artery to assess the perfusion of the skin flaps, and then mock transplanted.

RESULTS

Sizable perforators from the brachial, superior ulnar collateral, radial, ulnar, and posterior interosseous arteries were used to augment the vascularization of the skin flaps. The average stained area of the medial arm flap was between 85.7 and 93.9 percent. The stained area of the volar forearm flap was the smallest when based on perforators within 6 cm from the wrist crease (51.22 percent). The dorsal forearm flap showed the least amount of staining (34.7 to 46.1 percent). The average time to repair tendons, nerves, and vessels was longer when a single volar forearm-arm flap was harvested (171.6 minutes). Harvest of the allograft associated with a distally based forearm flap and islanded arm flap was the fastest (181.6 ± 17.55 minutes).

CONCLUSION

Extended skin flaps, based on perforators of the main axial vessels, can be reliably transplanted with a standard hand allograft based on the brachial or axillary vascular pedicle.

Iatrogenic carpal tunnel syndrome induced by wrist extension for placement of an indwelling radial artery catheter: a case report

A 38-year-old man with pancreatic cancer was scheduled to undergo pancreaticoduodenectomy. He had an unremarkable past medical history. After inducing general anesthesia, a left radial arterial catheter was successfully placed at first attempt. A wrist splint was used to obtain good arterial pulse waveforms.

After the operation, he was transferred to the intensive care unit. The radial artery catheter was removed on the fourth postoperative day. He experienced numbness and a tingling sensation in the left thumb, the second and third fingers, and the lateral half of the fourth finger. He was diagnosed with carpal tunnel syndrome. Diagnostic imaging revealed a swollen median nerve, but no hematoma or injury.

Some studies have suggested that excessive extension of the wrist may cause neuropathy. We recommend that patients’ wrists not be over-extended, even if good arterial waveforms cannot be obtained.

Is Serum Bicarbonate Level Associated With Negative Outcomes in Pediatric Patients?: A Retrospective Cohort Study

OBJECTIVES

Early identification of children at risk for adverse outcomes is important. Serum bicarbonate is easily collected and widely available. We described the relationship between bicarbonate and adverse outcomes in children presenting to the emergency department (ED).

METHODS

We conducted a retrospective cohort study of children aged 0 to 17 years from January 1, 2007, to December 31, 2011, who had a serum bicarbonate measured in the ED. Primary outcome was the predictive ability of bicarbonate for the individual components of the composite outcome that included at least one of the following: intensive care unit admission, assisted ventilation, inotropic support, cardiopulmonary resuscitation, or death. Secondary outcome was the relationship between bicarbonate level of greater and less than 13 mEq/L and the composite outcome.

RESULTS

We reviewed 16,989 charts, of which 432 had an adverse outcome. Receiver operating characteristic curve analysis showed that a bicarbonate level of less than 18.5 mEq/L predicted inotropic support with an area under the curve of 0.69 (95% confidence interval [CI], 0.60-0.77; P < 0.001) and death with an area under the curve of 0.75 (CI, 0.66-0.85; P < 0.001). Significantly more patients with bicarbonate level of less than 13 mEq/L had at least 1 adverse outcome compared with those with bicarbonate level of greater than 13 mEq/L (4.4% vs 2.5%, P = 0.001), odds ratio 1.96 (95% CI, 1.3-2.97).

CONCLUSIONS

Among children presenting to the ED, bicarbonate level of 18.5 mEq/L had fair specificity in predicting inotropic support and death. Negative outcomes are significantly associated with bicarbonate level of less than 13 mEq/L. Bicarbonate should routinely be measured in children at risk of clinical deterioration.

Evaluation of the Forearm Dominancy Artery for Invasive Vascular Procedure with 3D-CT Angiography

The aim of this study was to evaluate the vascular dominance in the forearm as a factor in determining the choice of invasive vascular procedures in arteries of the forearm, using 3D-computerized tomography (3D-CT) angiographies of 92 forearms. The diameters of the ulnar and radial arteries were measured just distal to the bifurcation of the brachial artery, at the midpoint between the bifurcation and the wrist, and at the wrist crease. In 79 cases, the ulnar artery was larger than the radial artery after the bifurcation of the brachial artery. However, no statistically significant difference was observed at either the mid-forearm or the wrist crease. In the remaining 13 cases, the diameter of the radial artery was larger or the same as that of the ulnar artery after the bifurcation, but at the more distal sites no regular pattern could be detected. The findings suggest that 3D-CT angiography offers valuable preoperative details of the forearm vessels for cases requiring invasive vascular procedures on the forearm.

Comparison of a continuous noninvasive arterial pressure device with invasive measurements in cardiovascular postsurgical intensive care patients: a prospective observational study

BACKGROUND

Arterial pressure monitoring using the a continuous noninvasive arterial pressure (CNAP) device during general anaesthesia is known to be interchangeable with continuous invasive arterial pressure (CIAP) monitoring. Agreement with invasive measurements in cardiovascular postsurgical intensive care patients has not been assessed.

OBJECTIVE

The objective of this study is to assess the agreement and interchangeability of CNAP with CIAP in cardiovascular postsurgical patients and to determine the effects of cardiac arrhythmia, catecholamine dosage, respiratory weaning and calibration intervals on agreement.

DESIGN

A prospective observational study.

SETTING

German university hospital cardiovascular ICU. Data were collected from April 2010 to December 2011.

PATIENTS

From 110 enrolled patients, 104 were included. Inclusion criteria were American Society of Anaesthesiologists (ASA) physical status III or IV patients undergoing controlled ventilation. Exclusion criteria included emergencies, complete heart block and marked arterial pressure differences greater than 10 mmHg in the two arms.

MAIN OUTCOME MEASURES

Bland-Altman plots, bias, precision, 95% limits of agreement, percentage error and agreement : tolerability indexes (ATIs) were estimated to determine clinical agreement.

RESULTS

From 11 222 arterial pressure readings, biases (SD) for CIAP-CNAP for systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) for all patients were 4.3 (11.6), -9.4 (8) and -6 (7.6) mmHg, respectively. Cardiac arrhythmia (4.1 (13.1), -14.4 (8.3), -9.5 (8.9) mmHg) and long interval to last calibration [4.5 (15), -9.8 (9.5), -6.4 (9.1) mmHg] impaired the accuracy of CNAP with failed interchangeability criteria defined by the percentage error. In contrast, use of catecholamines (epinephrine or norepinephrine infusions >0.1 μg kg min), short calibration intervals and weaning conditions did not affect accuracy, interchangeability and agreement, especially of MAP. Agreement was defined as acceptable for MAP for all data and subgroups (ATI 0.8 to 1.0) and at worst, marginal for SAP and DAP (ATI 0.9 to 1.6).

CONCLUSION

CNAP showed acceptable agreement defined by the ATI with invasive measurements for MAP and partially for DAP, but there was considerable variability for SAP. MAP should be preferred for clinical decision making. Cardiac arrhythmia, in contrast to catecholamine dosage or weaning procedures, impaired the accuracy, agreement and interchangeability of CNAP.

TRIAL REGISTRATION

Clinical trials.gov identifier NCT01003665.

[Posttraumatic aneurysm of the distal radial artery leading to digital ischemia]

Distal radial artery aneurysms are rare. We relate a case of non-iatrogenic distal radial artery aneurysm in the anatomical snuffbox leading to digital ischemia in a 43-year-old man.

Neurologic complications of cardiac tests and procedures

Arterial or central venous vascular access is the cornerstone of invasive cardiac diagnosis, monitoring, and therapeutics. Although procedural safety has significantly improved with protocols perfected over decades of use, their prevalence renders even the uncommon neurologic complication clinically relevant. Serious peripheral nerve complications result from direct or indirect nerve injuries in the setting of a hematoma or compartment syndrome. Functional outcome is dependent upon prompt diagnosis and early treatment, so proceduralists should be aware of the relevant anatomy and early signs of nerve injury. Ischemic stroke is the most common central nervous system complication of diagnostic and therapeutic cardiac catheterization, and is presumed to be due to embolization of atherosclerotic plaque or thrombus dislodged during guiding catheter manipulation, platelet-fibrin thrombus that forms on the catheters, or air that appears during catheter flushing. Acute neurologic deterioration after thrombolysis for acute myocardial infarction should be presumed to be an intracranial hemorrhage until proven otherwise. The ideal angiography suite of the future is patientcentric and multipurpose, coordinating diagnostic and therapeutic strategies for multivascular disease, allowing for multispecialty collaboration, and, in the event of a neurologic complication of a cardiac procedure, facilitating the various treating physicians to converge efficiently upon the patient.

A high bifurcation of the dorsal branch with dominant superficial palmar branch of the radial artery: a case report of an aberrant radial artery with traumatic aneurysm

Anatomical abnormalities such as unusual bifurcations or aberrant arteries of the radial artery are extremely rare and due to malformation or disruption of the vascular net. We present a case of a 64 year old woman with a high bifurcated dorsal branch of the left radial artery, consulting us for a pulsatile mass in the anatomical snuffbox after a fall. The mass measured 3-4 mm in diameter and was located on the dorsal aspect of the wrist over the anatomical snuffbox. Primary imaging studies using Duplex Ultrasound suggested an aneurysm of the radial artery, further imaging with arteriogram revealed a high bifurcation of the dorsal branch of the radial artery, presenting with an aneurysm. The deep palmar branch of the ulnar artery was the dominating vessel, allowing ligation and excision of the aneurysm. Histological evaluation revealed intimal wall hyperplasia within the aneurysm, suggesting an injury as initiating factor. A review of the literature showed that this abnormality of high bifurcation of the dorsal palmar branch of the radial artery has not been previously reported. Management of aneurysms at the wrist is discussed.

Pushing wrist access to the limit: homolateral right ulnar artery approach for primary percutaneous coronary intervention after right radial failure due to radial loop

A 67-year-old man underwent primary percutaneous coronary intervention for acute anterior ST elevation myocardial infarction. The right radial artery was the access of choice. After easy cannulation, a 360-degree loop was found at the elbow level. The brachial artery and a large ulnar artery were visible by injecting contrast through the radial loop. After an unsuccessful attempt to engage the loop, the operator switched entry site for the homolateral ulnar artery. Leaving the radial sheath in place, the cannulation of the ulnar artery was successful and uncomplicated. The operator could easily perform a successful intervention of the culprit vessel. An angiogram of the wrist, via the ulnar sheath showed the presence of a big interosseous artery with flow up to the hand and no flow in the radial and ulnar arteries distal to the sheaths. The ulnar and radial arteries were successfully sealed after a few hours, a valid pulsation was present on both arteries and no signs of ischemia were evident in the right hand the day after.

Femoral nailing during serum bicarbonate-defined hypo-perfusion predicts pulmonary organ dysfunction in multi-system trauma patients

OBJECTIVE

To assess the value of venous serum bicarbonate as an endpoint of resuscitation and guide to timing of femoral nailing in multi-system trauma patients.

DESIGN

Retrospective cohort study.

SETTING

Academic Level 1 Trauma Centre.

PATIENTS

Seventy-two consecutive adult multi-system trauma patients (Injury Severity Score≥15) with femoral shaft fracture (Orthopaedic Trauma Association Class 32-A to 32-C) treated with reamed medullary nail fixation.

INTERVENTION

Femoral nailing in the setting of hypo-perfusion defined by venous serum bicarbonate (SB). Threshold values of SB were determined first by correlating SB and simultaneously drawn arterial base deficit (BD). Then, corresponding values of SB to previously defined thresholds of hypo-perfusion based on BD were identified using regression analysis.

MAIN OUTCOME MEASUREMENT

Pulmonary organ dysfunction (POD) component of the Denver Multiple Organ Failure scoring system.

RESULTS

Simultaneous admission SB and BD values were correlated (r=-0.43, p=0.001). Adjusting for age, ISS and baseline POD, patients with SB<24.7 mequiv./L within 6 h of treatment had a 12-fold increase in POD (OR 12.2, 95% CI 1.5-98.6, p=0.019). This association was diminished, but still significant with hypo-perfusion present within 12 h prior to treatment (OR 5.6, 95% CI 1.0-29.1, p=0.042) and 24 h prior to treatment (OR 5.9, 95% CI 1.1-30.7, p=0.037).

CONCLUSIONS

Medullary fixation of femoral shaft fracture in the setting of serum bicarbonate-defined hypo-perfusion is associated with increased morbidity. Appropriate damage-control measures and aggressive resuscitation prior to definitive fracture care are advised and physiologic markers such as serum bicarbonate should guide clinical decision making rather than temporal distinctions.

[Ultrasound guided radial artery cannulation: procedure description and literature review]

Arterial catheterization is the second most common invasive procedure performed in critical care units. These devices are essential in certain types of patients (the hemodinamically unstable or those who require regular evaluation of the gasometric values). Complications related to arterial cannulation are relatively scarce. However, there are no reliable indicators to predict the occurrence of radial artery occlusions or ischemic lesions in the hand after a radial cannulation procedure has been performed. Ultrasound-guided catheter insertion has been used for years to guide central venous cannulation in critical care, but its use has been more limited for arterial catheterization. This paper aims to describe the technique of ultrasound-guided radial artery catheterization and reviews the most important research papers that have evaluated the safety and efficacy of this procedure in the adult population.

A comparison of differential oscillometric device with invasive mean arterial blood pressure monitoring in intensive care patients

Non-invasive beat-to-beat mean arterial pressure (MAP) in finger arteries recorded by the differential oscillometric device was compared with MAP recorded invasively from A. radialis in 22 patients after cardiac surgery. Based on all 132 paired measurements, the MAP values measured at the radial artery were 2.7 ± 4.9 mmHg higher than those measured on fingers. Among 22 patients there were 8 patients receiving inotropic support, their difference being 2.1 ± 5.6 mmHg. The present study revealed that the mean discrepancy between the invasive radial pressure and finger pressure was small; however, patient data sets showed marked variability in average pressure differences when examined individually.

Arterial prehabilitation: can exercise induce changes in artery size and function that decrease complications of catheterization?

Coronary angiography and angioplasty are common invasive procedures in cardiovascular medicine, which involve placement of a sheath inside peripheral conduit arteries. Sheath placement and catheterization can be associated with arterial thrombosis, spasm and occlusion. In this paper we review the literature pertaining to the possible benefits of arterial 'prehabilitation'--the concept that interventions aimed at enhancing arterial function and size (i.e. remodelling) should be undertaken prior to cardiac catheterization or artery harvest during bypass graft surgery. The incidence of artery spasm, occlusion and damage is lower in larger arteries with preserved endothelial function. We conclude that the beneficial effects of exercise training on both artery size and function, which are particularly evident in individuals who possess cardiovascular diseases or risk factors, infer that exercise training may reduce complication rates following catheterization and enhance the success of arteries harvested as bypass grafts. Future research efforts should focus directly on examination of the 'prehabilitation' hypothesis and the efficacy of different interventions aimed at reducing clinical complications of common interventional procedures.

Radial artery cannulation: a comprehensive review of recent anatomic and physiologic investigations

Consistent anatomic accessibility, ease of cannulation, and a low rate of complications have made the radial artery the preferred site for arterial cannulation. Radial artery catheterization is a relatively safe procedure with an incidence of permanent ischemic complications of 0.09%. Although its anatomy in the forearm and the hand is variable, adequate collateral flow in the event of radial artery thrombosis is present in most patients. Harvesting of the radial artery as a conduit for coronary artery bypass grafting, advances in plastic and reconstructive surgery of the hand, and its use as an entry site for cardiac catheterization has provided new insight into the collateral blood flow to the hand and the impact of radial arterial instrumentation. The Modified Allen's Test has been the most frequently used method to clinically assess adequacy of ulnar artery collateral flow despite the lack of evidence that it can predict ischemic complications in the setting of radial artery occlusion. Doppler ultrasound can be used to evaluate collateral hand perfusion in an effort to stratify risk of potential ischemic injury from cannulation. Limited research has demonstrated a beneficial effect of heparinized flush solutions on arterial catheter patency but only in patients with prolonged monitoring (>24 h). Conservative management may be equally as effective as surgical intervention in treating ischemic complications resulting from radial artery cannulation. Limited clinical experience with the ultrasound-guided arterial cannulation method suggests that this technique is associated with increased success of cannulation with fewer attempts. Whether use of the latter technique is associated with a decrease in complications has not yet been verified in prospective studies. Research is needed to assess the safety of using the ulnar artery as an alternative to radial artery cannulation because the proximity and attachments of the ulnar artery to the ulnar nerve may potentially expose it to a higher risk of injury.

Evaluation of the VIA Blood Chemistry Monitor for Glucose in Healthy and Diabetic Volunteers

BACKGROUND

Manual methods of blood glucose monitoring are labor-intensive, costly, prone to error, and expose the caregiver to blood. The VIA(R) blood chemistry monitor for glucose can automatically measure plasma glucose (PG) every 5 minutes for 72 hours using blood sampled from a peripheral vein/artery or a central vein.

METHODS

VIA performance was evaluated in eight normal and five type 1 diabetic (T1DM) subjects in 15 separate experiments. The VIA device was connected to a peripheral vein and reported a PG value every 5 minutes during each 510-minute experiment. Blood samples were collected manually every 10 minutes and assayed using a HemoCue(R) beta-glucose analyzer (HC). Whole blood HC measurements were corrected to PG values. Paired HC/VIA measurements (n = 717) were analyzed.

RESULTS

Mean PG was 90 +/- 14 and 96 +/- 12 mg/dl in normal subjects and 194 +/- 64 and 173 +/- 48 mg/dl in T1DM subject as measured by the HC and VIA, respectively. Clark error grid analysis revealed 86% points in zone A, 11% points in zone B, and 2% points in zone D. Linear regression analysis yielded the following equation: VIA = 0.732 x HC + 30.5 (r(2) = 0.954). Residual analysis revealed a glucose-dependent bias between the HC and the VIA. VIA data were transformed using the linear regression equation to correct for bias. After the correction, the mean absolute relative difference between the VIA and the HC was less than 10%, and 99.6% of data were in zones A and B. The VIA was able to sample blood automatically every 5 minutes for more than 8 hours in the laboratory setting. On average, the VIA reported glucose values for 94% of the samples it attempted to obtain.

CONCLUSIONS

This study demonstrated that the VIA blood chemistry monitor for glucose can reliably sample blood frequently for a prolonged period of time safely and effectively in diabetic and nondiabetic volunteers. Agreement between the two devices was the closest at normal glucose concentrations. After correcting for a glucose-dependent bias between the devices, the MARD was consistently less than 10% for all glucose ranges.

Complications of vascular catheters in the neonatal intensive care unit

Insertion of an intravascular catheter is the most common invasive procedure in the neonatal ICU. With every passing decade, technological innovations in catheter materials and sizes have allowed vascular access in infants who are smaller and sicker for purposes of blood pressure monitoring, blood sampling, and infusion of intravenous fluids and medications. There is, however, growing recognition of potential risks to life and limb associated with the use of intravascular catheters. This article reviews complications of venous and arterial catheters in the neonatal ICU and discusses treatment approaches and methods to prevent such complications, based on current evidence.

Discordance between lactate and base deficit in the surgical intensive care unit: which one do you trust?

PURPOSE

Both lactate and base deficit (BD) are used as predictors of injury severity and mortality. We examined the significance of these measures when used in combination, and particularly when they provide conflicting data.

METHODS

We reviewed all intensive care unit patients with simultaneously obtained lactate and BD measurements. The ability to predict mortality and hospital stay was compared alone, in combination, and when there was disagreement between the measures. Receiver operating characteristic curves were generated to compare predictive abilities.

RESULTS

There were 1,298 patients with 12,197 sets of paired laboratory data; 1,026 trauma patients and 272 surgical patients. Lactic acidosis was present in 41% and a significant BD level (> 2) was found in 52%. Nonsurvivors had higher admission lactate (6.2 vs. 3.3) and base deficit (6.1 vs. 3.2) levels than survivors (both P < .01), with a modest correlation (r = .52) between the measures. The admission lactate and BD levels had similar predictive ability for mortality, with areas under the receiver operating characteristic curve of .7 and .66, respectively (both P < .01). However, the predictive ability of the BD level decreased significantly during the intensive care unit stay (area, .5) compared with lactate level (area, .68). Lactate and BD levels disagreed in 44% of all laboratory sets. In patients with a normal lactate level (< 2.2), the BD level had no predictive ability for mortality (area, .48; P = .26). However, in patients with a normal BD level (< 2.0), the lactate level retained its predictive ability for mortality (area, .67; P < .01). Lengths of stay were longer among patients with an increased lactate level, even when the BD level was normal. There was no improvement in predictive ability using a combination of the 2 measures.

CONCLUSIONS

Both lactate and BD levels may be used to identify lactic acidosis and predict mortality at admission. Increased lactate levels predict mortality and a prolonged course regardless of the associated BD level, whereas an increased BD level has no predictive value if the lactate level is normal.

Serum bicarbonate may replace the arterial base deficit in the trauma intensive care unit

OBJECTIVE

Arterial base deficit (BD) is a commonly used marker of injury severity and endpoint of resuscitation but requires an arterial puncture and blood gas analysis. Serum bicarbonate (HCO3) is routinely obtained as part of the chemistry panel on most admissions. We hypothesized that serum HCO3 strongly correlates with arterial BD and provides equivalent predictive information.

METHODS

All trauma ICU admissions from 1996 to 2004 with simultaneously obtained serum chemistry panels and arterial blood gases were identified. Correlation between BD and HCO3 was analyzed by using linear regression, and predictive abilities for acidoses and mortality were compared using the area under the respective receiver operating characteristic curve (AUC). Separate analyses were done for the entire dataset and the subset of ICU admission laboratory values.

RESULTS

We identified 3,102 patients with 50,311 matched pairs of laboratory data. Serum HCO3 showed a significant linear correlation with BD for all laboratory sets (r = 0.85, P < .01) and admission laboratory values only (r = 0.80, P < .01). Serum HCO3 reliably predicted the presence of significant metabolic acidoses (BD >5), with an AUC of 0.96 (P < .01), which clearly outperformed pH (AUC = 0.83), anion gap (AUC = 0.7), and lactate (AUC = 0.73). The mean admission BD among survivors was 2.5 versus 5.2 for nonsurvivors (P < .01), and the mean HCO3 was 17.7 versus 19.8 (P < .01). The admission HCO3 identified nonsurvivors as accurately as BD (AUCs of 0.66 and 0.68) and more accurately than either pH (AUC = 0.53) or anion gap (AUC = 0.6).

CONCLUSION

Serum HCO3 measurement shows a strong linear correlation and similar predictive ability compared with the arterial BD. Serum HCO3 may be safely and accurately substituted for arterial BD measurement in critically injured patients.