Impact of blood collection devices and mode of transportation on peripheral venous blood gas parameters

BACKGROUND

Peripheral venous blood (PVB) gas analysis has become an alternative to arterial blood gas (BG) analysis in assessing acid-base balance. This study aimed to compare the effects of blood collection devices and modes of transportation on peripheral venous BG parameters.

METHODS

PVB-paired specimens were collected from 40 healthy volunteers into blood gas syringes (BGS) and blood collection tubes (BCT), transported by either a pneumatic tube system (PTS) or human courier (HC) to the clinical laboratory, and compared using a two-way ANOVA or Wilcoxon signed-rank test. To determine clinical significance, the PTS and HC-transported BGS and BCT biases were compared to the total allowable error (TEA).

RESULTS

PVB partial pressure of oxygen (pO2), fractional oxyhemoglobin (FO2Hb), fractional deoxyhemoglobin (FHHb), and oxygen saturation (sO2) showed statistically significant differences between BGS and BCT (p < 0.0001). Compared to HC-transported BGS and BCT, statistically significant increases in pO2, FO2Hb, sO2, oxygen content (only in BCT) (all p < 0.0001), and base excess extracellular (only in BCT; p < 0.0014) concentrations and a statistically significant decrease in FHHb concentration (p < 0.0001) were found in BGS and BCT delivered by PTS. The biases between PTS- and HC-transported BGS and BCT exceeded the TEA for many BG parameters.

CONCLUSIONS

Collecting PVB in BCT is unsuitable for pO2, sO2, FO2Hb, FHHb, and oxygen content determinations.

Emergency Department Point-of-Care Tests during Cardiopulmonary Resuscitation to Predict Cardiac Arrest Outcomes

Introduction

This study evaluated the role of point-of-care tests (POCT) such as blood lactate, anion gap (AG), base deficit, pH, N-terminal pro B-type natriuretic peptide (NT-proBNP), and troponin as the predictors of cardiac arrest outcomes in the emergency department (ED).

Methods

We conducted a prospective, observational study in the ED of a tertiary care hospital in India. All the adult patients who received cardiopulmonary resuscitation (CPR) in the ED were included in the study. Blood samples were collected within 10 min of initiation of CPR for assay of POCTs. Outcomes assessed were the return of spontaneous circulation (ROSC), 24-h survival, survival to hospital discharge (STHD), survival at 7 days, and favorable neurological outcome (FNO) at day 7 of admission.

Results

One hundred and fifty-one patients were included in the study (median age: 50 years, 65% males). Out of 151 cases, ROSC, survival at 7 days, STHD, and FNO was observed in 86 patients, six patients, five patients, and two patients, respectively. "No-ROSC" could be significantly predicted by raised lactate (odds ratio [OR]: 1.14, 95% confidence interval: 1.07-1.22) and NT-proBNP (OR: 1.05, 1.01-1.09) values at the time of cardiac arrest. "24-h mortality" could be significantly predicted by the raised lactate (OR: 1.14, 1.01-1.28), low arterial pH (OR: 0.05, 0.01-0.52), raised AG (OR: 1.08, 1.01-1.15), and lower base deficit (<-15) (OR: 1.07, 1.01-1.14). None of the other POCTs was found to be a predictor of other cardiac arrest outcomes.

Conclusion

Among various POCTs, raised lactate assayed within 10 min of cardiac arrest can predict poor outcomes like "no-ROSC" and 24-h mortality.

Correlation and agreement between arterial and venous blood gas analysis in patients with hypotension-an emergency department-based cross-sectional study

BACKGROUND

Blood gas analysis is integral to assessing emergency department (ED) patients with acute respiratory or metabolic disease. Arterial blood gas (ABG) is the gold standard for oxygenation, ventilation, and acid-base status but is painful to obtain. Peripheral venous blood gas (VBG) is a valuable alternative as it is less painful and easy to collect. The comparability of ABG and VBG was studied in various conditions. But in hypotension, previous findings were inconsistent. So, we studied the correlation and agreement between ABG and VBG in hypotensive patients.

METHODOLOGY

The study was conducted at the emergency department of a tertiary healthcare center in Northern India. Patients with hypotension above 18 years who satisfied the inclusion criteria were clinically evaluated. Patients who require ABG as a part of routine care were sampled. ABG was collected from the radial artery. VBG was obtained from the cubital or dorsal hand veins. Both samples were collected within 10 min and were analyzed. All ABG and VBG variables were entered in premade proforma. The patient was then treated and disposed of according to institutional protocol.

RESULTS

A total of 250 patients were enrolled. The mean age was 53.25 ± 15.71 years. 56.8% were male. The study included 45.6% septic, 34.4% hypovolemic, 18% cardiogenic, and 2% obstructive shock patients. The study found a strong correlation and agreement for ABG and VBG pH, pCO2, HCO3, lactate, sodium, potassium, chloride, ionized calcium, blood urea nitrogen, base excess, and arterial/alveolar oxygen ratio. Hence, regression equations were made for the aforementioned. There was no correlation observed between ABG and VBG pO2 and SpO2. Our study concluded that VBG could be a reasonable alternative for ABG in hypotensive patients. We can also mathematically predict values of ABG from VBG using regression equations derived.

CONCLUSIONS

ABG sampling causes most unpleasant experiences to patients and is associated with complications like arterial injury, thrombosis, air or clotted-blood embolism, arterial occlusion, hematoma, aneurysm formation, and reflex sympathetic dystrophy. The study has shown strong correlations and agreements for most ABG and VBG parameters and can predict ABG mathematically using regression formulas formulated from VBG. This will decrease needle stick injury, consume less time, and make blood gas evaluation easy in hypotensive settings.

Accuracy and stability evaluation of different blood sampling methods in blood gas analysis in emergency patients: A retrospective study

BACKGROUND

To evaluate the accuracy and stability of arterial blood gas (ABG) results by comparison with venous measurements from routine blood tests, and to compare the accuracy and performance of two sampling syringes, pre-heparinized syringe (PHS) and disposable arterial blood syringe (DABS), in ABG analysis.

METHODS

We retrospectively analyzed the practical use of PHS and DABS in collecting ABG samples, involving 500 and 400 patients, respectively. For each patient, in addition to the ABG sample, a venous blood sample was also collected using a venous blood collection tube (VBCT) and used for routine blood tests. Accordingly, patients were referred to as the PHS + VBCT group and DABS + VBCT group. The correlation between arterial and venous values of each blood parameter in each group was evaluated using the interclass correlation coefficient (ICC). Bland-Altman was performed to evaluate the agreement between arterial and venous values and compare the performance of PHS and DABS in ABG sample collection.

RESULTS

In the PHS + VBCT group, arterial K⁺ , Na⁺ , hemoglobin (Hb), and hematocrit (HCT) were 0.32 mmol/L, 2.90 mmol/L, 2.21 g/L, and 1.27% significantly lower their corresponding venous values while arterial Cl^- was 7.60 mmol/L significantly higher than venous Cl^- . In the DABS + VBCT group, arterial K⁺ and Na⁺ were 0.20 mmol/L and 1.19 mmol/L significantly lower while Cl^- and HCT in arterial blood were 5.34 mmol/L and 0.66% significantly higher than their corresponding venous values. In both groups, arterial K⁺ , Na⁺ , Hb, and HCT values were highly consistent with their corresponding venous values, with all ICCs greater than 0.70, especially Hb and HCT. Bland-Altman analysis demonstrated that arterial K⁺ and Na⁺ were more consistent with venous counterparts in the DABS + VBCT group, with a narrower 95% limits of agreement than the PHS + VBCT group (K⁺ , -0.7-0.3 mmol/L vs. -1.1 to 0.5 mmol/L; Na⁺ , -5.8 to 3.4 mmol/L vs. -8.2 to 2.4 mmol/L).

CONCLUSION

Arterial blood gas analysis of K⁺ , Na⁺ , Hb, and HCT using PHS or DABS for blood sampling is accurate and stable, especially DABS, which can provide clinicians with fast and reliable blood gas results.

Utility of venous blood gases for the assessment of traumatic shock: a prospective observational study

BACKGROUND

ABG samples are often obtained in trauma patients to assess shock severity. Venous blood gas (VBG) sampling, which is less invasive, has been widely used to assess other forms of shock. The study aim was to determine the agreement between VBG and ABG measurements in trauma.

METHODS

Patients were enrolled at an Australian trauma centre between October 2016 and October 2018. Bland-Altman limits of agreement (LOA) between paired blood gas samples taken <30 min apart were used to quantify the extent of agreement. The impact of using only VBG measurements was considered using an a priori plan. Cases where venous sampling failed to detect 'concerning levels' were flagged using evidence-based cut-offs: pH ≤7.2, base deficit (BD) ≤-6, bicarbonate <21 and lactate ≥4. Case summaries of these patients were assessed by independent trauma clinicians as to whether an ABG would change expected management.

RESULTS

During the study period 176 major trauma patients had valid paired blood gas samples available for analysis. The median time difference between paired measurements was 11 min (IQR 6-17). There was a predominance of men (81.8%) and blunt trauma (92.0%). Median Injury Severity Score was 13 (range 1-75) and inpatient mortality was 6.3%. Mean difference (ABG-VBG) and LOA between paired arterial and venous measurements were 0.036 (LOA -0.048 to 0.120) for pH, -1.27 mmol/L (LOA -4.35 to 1.81) for BD, -0.64 mmol/L (LOA -1.86 to 0.57) for lactate and -1.97 mmol/L (LOA -5.49 to 1.55) for bicarbonate. Independent assessment of the VBG 'false negative' cases (n=20) suggested an ABG would change circulatory management in two cases.

CONCLUSIONS

In trauma patients VBG and ABG parameters displayed suboptimal agreement. However, in cases flagged as VBG 'false negative' independent review indicated that the availability of an ABG was unlikely to change management.