PURPOSE:To evaluate inadvertent warming of the infusion syringe in four different types of electronic syringe pumps.METHODS:Ambient temperature and syringe surface temperature were simultaneously measured by two electronic temperature probes in four different models of commercially available syringe pumps. Experiments were performed at an infusion rate of 1 ml h(-1) using both battery-operated and main power-operated pumps. Measurements were repeated four times with two pumps from each of the four syringe pump types at a room temperature of approximately 23 degrees C. Differences among the four syringe pump brands regarding ambient to syringe temperature gradient were compared using ANOVA. A P-value of less than 0.05 was considered statistically significant.RESULTS:Syringe warming differed significantly between the four syringe brands for both the battery-operated and main power-operated mode (ANOVA, P< 0.001 for both modes). Individual differences between syringe surface and ambient temperature ranged from 0.3 to 1.9 degrees C for battery operation and from 0.5 to 11.2 degrees C during main-power operation.CONCLUSION:Infusion solutions can be significantly warmed by syringe pumps. This has potential impact on bacterial growth and the stability of drug solutions and blood products infused, as well as on the susceptibility to hydrostatic pressure changes within the infusion syringe.

Using 10 different infusion bag pressure pumps, indicated manometer pressures were compared with measured infusion pressures proximal to the flow-regulating device in an in vitro experiment. Flow rates delivered through the flow-regulating device were gravimetrically measured at different monitored pressure levels. Significant differences were found between manometer and measured infusion pressures among the tested pressure bagpumps (e.g. 500 ml bag volumepressurized to 300 mmHg manometerpressure: 219.6 +/- 7.8 to 407.2 +/- 2.7 mmHg). The infusion pressures were additionally affected by the vertical level of the infusion bag pump and by the volume of the infusion bag. Flow rates delivered through the flow-regulating device were directly correlated to the measured infusion pressure (r2= 0.9926). Differences inflow rates can have a considerable impact on maintaining catheter patency and avoidance of fluid overload and retrograde flushing into the central arterial circulation in neonates and small children. A simple manoeuvre using the invasive pressure transducer allows monitoring and adjustment of the infusion pressure in the clinical setting.

BACKGROUND:The aim of this study was to measure the volumes of fluid delivered with a fast flush bolus from a flow regulating device.METHODS:In-vitro fast flush bolus volumes, the volumes delivered from a bag pump flush system while opening the flow regulating device for 1, 2 or 5 s, were gravimetrically measured through a 22-G and a 24-G cannula. In-vivo 1- and 2-s fast flush bolus volumes and the volume required to purge the tubing between stopcock and arterial cannula from visible blood after blood sampling were recorded in 12 anaesthetized neonates and infants (mean age 2.17 +/- 1.97 months, range 0.26-5.37 months) with a 24-G radial arterial cannula by continuously weighing the bag pump flush system at manometer pressures of 100, 200 and 300 mmHg.RESULTS:In-vitro fast flush bolus volumes ranged from 0.23 +/- 0.04 ml (1-s, 100 mmHg, 24-G cannula) to 2.95 +/- 0.38 ml (5-s, 300 mmHg, 22-G cannula). Volumes were larger using a 22-G cannula than a 24-G cannula (P < 0.01) and increased with longer flushing periods (P < 0.0001) and higher manometer pressures (P < 0.0001). In-vivo 1- and 2-s fast flush bolus volumes correlated well with driving pressures (infusion pressure minus mean arterial pressure) (r2 = 0.81/0.72). 1-s fast flush bolus volumes delivered (ml) were 0.0025 x mmHg driving pressure and 2-s fast flush bolus volumes delivered (ml) were 0.0043 x mmHg driving pressure. The mean volume delivered to purge blood from the arterial pressure tubing was 0.94 +/- 0.18 ml (range 0.61-1.34 ml).CONCLUSIONS:Fast bolus flushing from pressurized infusion bag systems, using the flow regulating device tested, can be applied during neonatal and paediatric anaesthesia without delivering uncontrolled amounts of fluid.

OBJECTIVE:Hand-held flushing of radial arterial lines at 0.5 ml/s in neonates can result in retrograde embolization of flush solution into the central arterial circulation. We studied flush flow velocities during intermittent arterial line purging using a flow regulating device with an infusion bag pump and a syringe pump system.MEASUREMENTS AND INTERVENTIONS:In this in vitro experiment we simulated flushing of a 24- and a 22-G cannula against a mean arterial pressure of 45 mmHg. Fluid flow velocities were gravimetrically measured during flushing from an infusion bag system pressurized to 100, 200, and 300 mmHg and from a syringe pump flush system after initialization of boluses of 0.5, 1.0, 1.5, 2.0, and 2.5 ml. The flow regulating device was opened for 1, 2, and 5 s.RESULTS:Both flush systems tested allowed delivery of flush flow velocities exceeding 0.5 ml/s (e.g., 22-G cannula; bag system, pressure 300 mmHg up to 0.64+/-0.08 ml/s; syringe pump, 2 ml bolus up to 0.74+/-0.05 ml/s). In syringe pump systems the main determinant of flow velocity was bolus size, in bag pump systems flushing time and bag pressure.CONCLUSIONS:Based on data about critical flow velocities through an radial arterial cannula in neonates, both tested flushing systems carry the risk of exceeding the critical value of 0.5 ml/s. They are likely to cause retrograde embolization of flushing solution into the central arterial circulation with the associated risk of clot and air embolization. In vivo studies should identify margins of safety to minimize the risk of retrograde flushing into the central arterial circulation.

Saline tonometry has been replaced by automated air tonometry (TONOCAP ® ). As with saline tonometry there are some pitfalls to consider. We investigated the influence of different filling handicaps to the tonometry catheter sampling balloon on measurement of regional PCO 2 (PrCO 2 ). In an in vitro set-up, PrCO 2 was measured using the TONOCAP ® at intervals of 10 minutes from a 8F tonometry catheter sampling balloon placed in a container with constant PCO 2 (PcCO 2 ). Catheter alarms displayed by the TONOCAP® device were noted. The following experiments were performed: A) control measurement without modifications; B) adding deadspace of 7 ml into the sampling line; C) placing the sampling balloon in a 3 ml syringe; D) cross-clamping of the sampling balloon. Each experiment was performed four times using two catheters on two TONOCAP ® devices. Differences between PcCO 2 and PrCO 2 were calculated as Pc-rCO 2. Results are presented as mean±SD and were compared using ANOVA with Scheffe's correction. Pc-rCO 2 in the control set-up (A) amounted to 0.16±0.22%. Increasing catheter deadspace (B) resulted in a higher Pc-rCO 2 of 3.2±0.57% (P<0.0001). Restriction of balloon expansion (C) caused an Pc-rCO 2 gap of 1.17±0.36% (P<0.0001). With filling restriction (D) the Pc-rCO 2 gap increased to 3.87±0.29% (P<0.0001). The catheter alarms provided were not able to indicate all catheter problems and initial alarms disappeared although the problems continued. We conclude that impaired catheter deadspace to balloon volume relation can negatively influence accuracy of PrCO 2 measurement by the TONOCAP ®.

A study was made of the pattern of congenital transmission of RIF, a naturally occurring avian leukosis virus, in a flock of chickens selected for a high incidence of neoplasms. It was found that about 1 out of every 6 hens had a persistent RIF-viremia, and all such hens infected their embryos regularly. One out of every 7 non-viremic hens was also a congenital transmitter of RIF, but the transmission was somewhat more erratic than in the case of the viremic birds. There was no indication that roosters, viremic or otherwise, could transmit RIF to their progeny, and it was concluded that the congenital transmission of RIF was strictly maternal.

Understanding household behavior and its macro consequences for society is pivotal for climate change adaptation. Yet, traditional policy decision-support models for nature–society systems oversimplify human behavior. Using original modeling ...Despite the growing calls to integrate realistic human behavior in sustainability science models, the representative rational agent prevails. This is especially problematic for climate change adaptation that relies on actions at various scales: from ...