Effect of vertical stopcock position on start-up fluid delivery in syringe pumps used for microinfusions.

The purpose of this in vitro study was to evaluate the impact of the vertical level of the stopcock connecting the infusion line to the central venous catheter on start-up fluid delivery in microinfusions. Start-up fluid delivery was measured under standardized conditions with the syringe outlet and liquid flow sensors positioned at heart level (0 cm) and exposed to a simulated CVP of 10 mmHg at a set flow rate of 1 ml/h. Flow and intraluminal pressures were measured with the infusion line connected to the stopcock primarily placed at vertical levels of 0 cm, + 30 cm and - 30 cm or primarily placed at 0 cm and secondarily, after connecting the infusion line, displaced to + 30 cm and - 30 cm. Start-up fluid delivery 10 s after opening the stopcock placed at zero level and after opening the stopcock primarily connected at zero level and secondary displaced to vertical levels of + 30 cm and - 30 cm were similar (- 10.52 [- 13.85 to - 7.19] µL; - 8.84 [- 12.34 to - 5.33] µL and - 11.19 [- 13.71 to - 8.67] µL (p = 0.469)). Fluid delivered at 360 s related to 65% (zero level), 71% (+ 30 cm) and 67% (- 30 cm) of calculated infusion volume (p = 0.395). Start-up fluid delivery with the stopcock primarily placed at + 30 cm and - 30 cm resulted in large anterograde and retrograde fluid volumes of 34.39 [33.43 to 35.34] µL and - 24.90 [- 27.79 to - 22.01] µL at 10 s, respectively (p < 0.0001). Fluid delivered with the stopcock primarily placed at + 30 cm and - 30 cm resulted in 140% and 35% of calculated volume at 360 s, respectively (p < 0.0001). Syringe infusion pumps should ideally be connected to the stopcock positioned at heart level in order to minimize the amounts of anterograde and retrograde fluid volumes after opening of the stopcock.

Pressure-adjusted venting eliminates start-up delays and compensates for vertical position of syringe infusion pumps used for microinfusion.

Microinfusions are commonly used for the administration of catecholamines, but start-up delays pose a problem for reliable and timely drug delivery. Recent findings show that venting of the syringe infusion pump with draining of fluid to ambient pressure before directing the flow towards the central venous catheter does not counteract start-up delays. With the aim to reduce start-up delays, this study compared fluid delivery during start-up of syringe infusion pumps without venting, with ambient pressure venting, and with central venous pressure (CVP)-adjusted venting. Start-up fluid delivery from syringe pumps using a microinfusion of 1 mL/h was assessed by means of liquid flow measurement at 10, 60, 180 and 360 s after opening the stopcock and starting the pump. Assessments were performed using no venting, ambient pressure venting or CVP-adjusted venting, with the pump placed either at zero, - 43 cm or + 43 cm level and exposed to a simulated CVP of 10 mmHg. Measured fluid delivery was closest to the calculated fluid delivery for CVP-adjusted venting (87% to 100% at the different timepoints). The largest deviations were found for ambient pressure venting (- 1151% to + 82%). At 360 s after start-up 72% to 92% of expected fluid volumes were delivered without venting, 46% to 82% with ambient pressure venting and 96% to 99% with CVP-adjusted venting. CVP-adjusted venting demonstrated consistent results across vertical pump placements (p = 0.485), whereas the other methods had significant variances (p < 0.001 for both). In conclusion, CVP-adjusted venting effectively eliminates imprecise drug delivery and start-up delays when using microinfusions.

Risk factors for postoperative hyperglycemia in neonates.

OBJECTIVE: Postoperative hyperglycemia has been shown to be associated with higher morbidity and mortality in pediatric patients. Data on risk factors for neonatal patients is limited. The objective of this study was to identify pre- and intraoperative risk factors associated with postoperative glucose in neonates. METHODS: We conducted a retrospective cohort study of neonates after surgical procedures between January and December 2016 in a quaternary neonatal intensive care unit. The primary outcome was hyperglycemia defined as serum glucose ≥8.3 mmol/L during the first 4 hours postoperatively. Secondary outcomes included death and length of stay. We assessed the association of risk factors with the postoperative glucose. RESULTS: In total, 206 surgical procedures (171 patients) were evaluated, among which 178 had serum glucose values during the first 4 hours postoperatively available. The incidence of hyperglycemia was 54% (n = 96). The median (IQR) glucose during the first 4 hours in NICU was 8.4 (6.52-10.65) mmol/L. Risk factors for postoperative hyperglycemia were intraoperative glucose infusion rate (GIR) and gestational age. There was a non-linear relationship between gestational age and postoperative hyperglycemia. Mortality occurred in 6 (7%) in the no-hyperglycemia group and 3 (3%) in the hyperglycemia group (p = 0.31). CONCLUSIONS: Among the risk factors, intraoperative GIR was identified as a modifiable factor that can reduce postoperative hyperglycemia. A non-linear relationship of gestational age with postoperative glucose provides new insights that may help advance our understanding of the complex mechanisms of glucose homeostasis in neonates.

Flow irregularities from syringe infusion pumps caused by syringe stiction.

OBJECTIVE: The current study aimed to evaluate the extent of the slide-stick phenomenon in differently designed infusion syringes at various infusion rates and filling positions. METHODS: Fluid delivery from three 50-mL infusion syringe brands (BD; Codan; Fresenius) was investigated using a flow sensor at flow rates of 0.5, 1.0, or 5.0 mL h-1 , with the syringes filled with either 10, 30, or 50 mL of distilled water. Two identical models (A/B) of the same infusion pump model were used. The effect of flow rate variations on the plasma concentration of a continuous epinephrine infusion in a 3 kg neonate receiving a continuous infusion of 0.1 µg kg min-1 epinephrine was studied using a pharmacokinetic simulation model. RESULTS: Considerable variations in calculated plasma epinephrine concentration were detected between flow rates of 5 and 0.5 or 1 mL h-1 for all syringe types and filling volumes. The median deviation of plasma concentration for the 5 mL h-1 flow rate varied depending on assembly from 1.3% (Codan) to 1.8% (Fresenius). This was more pronounced for lower flow rates, where at 1 mL h-1 the deviation varied from 3.3% (BD) to 4.8% (Fresenius) and at 0.5 mL h-1 from 4.9% (BD) to 5.4% (Fresenius). Differences between filling volumes (within syringe type and flow rate) did not appear to have relevant influence on variations in calculated plasma epinephrine concentration. CONCLUSION: Infusion set rate rather than syringe brand or filling volume was a major predictor for syringe stiction-related amount of variation in the calculated plasma epinephrine concentration.

Plasma Proendothelin-1 as an Early Marker of Bronchopulmonary Dysplasia.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a common complication in preterm infants. Clinical prediction of BPD at an early stage in life is difficult. Plasma proendothelin-1 (CT-proET-1) is a lung injury biomarker in pulmonary hypertension and respiratory distress. OBJECTIVE: To assess the prognostic ability of CT-proET-1 in BPD. METHODS: In 227 prospectively enrolled preterm infants born at <32 weeks gestational age (GA), plasma CT-proET-1 was measured at birth, day of life (DOL) 2, 3, 6 and 28, and at 36 weeks postmenstrual age (PMA). BPD was defined as mild in infants requiring supplemental oxygen at DOL 28 and moderate/severe in those requiring it at 36 weeks PMA. RESULTS: The predictive ability of CT-proET-1 for any BPD was poor at birth [area under the ROC curve (AUC) 0.654, 95% CI 0.494-0.814], moderate at DOL 2 and 3 (AUC 0.769, 95% CI 0.666-0.872) and excellent at DOL 6 (AUC 0.918, 95% CI 0.840-0.995). Multivariable regression analysis revealed that CT-proET-1 levels at DOL 2, 3, 6 and 28 were strongly related to the duration of oxygen supplementation, independently of GA and the duration of respiratory support. CONCLUSIONS: CT-proET-1 is a novel promising biomarker for predicting the development of BPD in preterm infants when measured at the end of the first week of life.

Immunohistochemical detection of EGFR, fibrillin-2, P-cadherin and AP2beta as biomarkers for rhabdomyosarcoma diagnostics.

AIMS: Subclassification of rhabdomyosarcoma (RMS) has clinical relevance, as the two major subclasses embryonal (ERMS) and alveolar (ARMS) rhabdomyosarcoma differ greatly in terms of aggressiveness and prognosis. However, histological analysis is not always sufficient for an unequivocal subclassification of RMS. Furthermore, clinical presentation of ARMS has been reported to mimic other tumour types, specifically lymphoma. The aim was to determine the role of four biomarkers in the diagnosis of rhabdomyosarcoma. METHODS AND RESULTS: Recently, we identified four potential biomarkers to subclassify RMS with high sensitivity and specificity. These included epidermal growth factor receptor (EGFR) and fibrillin-2 as markers for ERMS, and AP2beta and P-cadherin as markers for translocation-positive ARMS. Here, we further validate the potential of these four markers in a second, independent patient cohort by immunohistochemistry on 80 sections of RMS biopsy specimens as well as a tissue microarray representing 18 different additional tumour types, including seven lymphomas. The combination of EGFR and fibrillin-2 was able to detect ERMS with a specificity of 76% and sensitivity of 90%. The combination of AP2beta and P-cadherin detected ARMS with a specificity of 97% and sensitivity of 90%, data very similar to our previous study. Furthermore, all lymphomas were clearly negative for AP2beta and P-cadherin. CONCLUSIONS: These four biomarkers are suitable for clinical implementation in the future diagnosis of RMS.