Background: Elastomeric pumps (elastic balls into which analgesics or antibiotics can be inserted) push medicines through a catheter to a nerve or blood vessel. Since elastomeric pumps are small and need no power sour...Background: Elastomeric pumps (elastic balls into which analgesics or antibiotics can be inserted) push medicines through a catheter to a nerve or blood vessel. Since elastomeric pumps are small and need no power source, they fit easily into a pocket during infusion, allowing patient mobility. Elastomeric pumps are widely used and widely studied experimentally, but they have well-known problems, such as maintaining reliable flow rates and avoiding toxicity or other peak-and-trough effects. Objectives: Our research objective is to develop a realistic theoretical model of an elastomeric pump, analyze its flow rates, determine its toxicity conditions, and otherwise improve its operation. We believe this is the first such theoretical model of an elastomeric pump consisting of an elastic, medicine-filled ball attached to a horizontal catheter. Method: Our method is to model the system as a quasi-Poiseuille flow driven by the pressure drop generated by the elastic sphere. We construct an engineering model of the pressure exerted by an elastic sphere and match it to a solution of the one-dimensional radial Navier-Stokes equation that describes flow through a horizontal, cylindrical tube. Results: Our results are that the model accurately reproduces flow rates obtained in clinical studies. We also discover that the flow rate has an unavoidable maximum, which we call the “toxicity bump”, when the radius of the sphere approaches its terminal, unstretched value—an effect that has been observed experimentally. Conclusions: We conclude that by choosing the properties of an elastomeric pump, the toxicity bump can be restricted to less than 10% of the earlier, relatively constant flow rate. Our model also produces a relation between the length of time that the analgesic fluid infuses and the physical properties of the fluid, of the elastomeric sphere and the tube, and of the blood vessel into which the analgesic infuses. From these, we conclude that elastomeric pumps can be designed, using our simple model, to control infusion times while avoiding toxicity effects.展开更多
AIM: To evaluate pain control in chronic pancreatitis patients who underwent total pancreatectomy with islet cell transplantation or intrathecal narcotic pump infusion.METHODS: We recognized 13 patients who underwent ...AIM: To evaluate pain control in chronic pancreatitis patients who underwent total pancreatectomy with islet cell transplantation or intrathecal narcotic pump infusion.METHODS: We recognized 13 patients who underwent intrathecal narcotic pump(ITNP) infusion and 57 patients who underwent total pancreatectomy with autologous islet cell transplantation(TP + ICT) for chronic pancreatitis(CP) pain control between 1998 and 2008 at Indiana University Hospital. All patients had already failed multiple other modalities for pain control and the decision to proceed with either intervention was made at the discretion of the patients and their treating physicians. All patients were evaluated retrospectively using a questionnaire inquiring about their pain control(using a 0-10 pain scale), daily narcotic dose usage, and hospital admission days for pain control before each intervention and during their last follow-up. RESULTS: All 13 ITNP patients and 30 available TP + ICT patients were evaluated. The mean age was approximately 40 years in both groups. The median duration of pain before intervention was 6 years and 7 years in the ITNP and TP + ICT groups, respectively. The median pain score dropped from 8 to 2.5(on a scale of 0-10) in both groups on their last follow up. The median daily dose of narcotics also decreased from 393 mg equivalent of morphine sulfate to 8 mg in the ITNP group and from 300 mg to 40 mg in the TP + ICT group. No patient had diabetes mellitus(DM) before either procedure whereas 85% of those who underwent pancreatectomy were insulin dependent on their last evaluation despite ICT. CONCLUSION: ITNP and TP + ICT are comparable for pain control in patients with CP however with high incidence of DM among those who underwent TP + ICT. Prospective comparative studies and longer follow up are needed to better define treatment outcomes.展开更多
Reliability of medical devices such as infusion pumps is extremely important because these devices are being used in patients who are in critical condition. Occlusion pressure, as an important parameter of infusion pu...Reliability of medical devices such as infusion pumps is extremely important because these devices are being used in patients who are in critical condition. Occlusion pressure, as an important parameter of infusion pumps, should be detected when an occlusion occurred. How-ever, infusion pumps’ occlusion pressure could not be tested and the performance of these pumps is not known to us. In order to test the occlusion pressure of infusion pump, a testing system has been put forward according to standards of IEC 60601-2-24:1998/ GB 9706.27- 2005. The system is comprised of sensor, acquisition card, three-way tap and so on;this system is controlled by a PC. At the same time, sampling rate could be changed if necessary and test time could be recorded. And then the characteristics of this system were studied, such as linear, effects of pump rates and different pumps. The system remained linear in a given environment. The higher is the pump rate, the faster is the time to reach occlusion condi-tion. The testing system has been proved to be effective in testing the occlusion pressure of infusion pumps and the accuracy error of pressure is content the demand of ±1% of range.展开更多
BACKGROUND Critically ill neonates and pediatric patients commonly require multiple low flow infusions.Volume limitations are imposed by small body habitus and comorbidities like cardiopulmonary disease,renal failure,...BACKGROUND Critically ill neonates and pediatric patients commonly require multiple low flow infusions.Volume limitations are imposed by small body habitus and comorbidities like cardiopulmonary disease,renal failure,or fluid overload.Vascular access is limited by diminutive veins.Maintenance fluids or parenteral nutrition in conjunction with actively titrated infusions such as insulin,fentanyl,prostaglandins,inotropes and vasopressors may necessitate simultaneous infusions using a single lumen to maintain vascular catheter patency.This requirement for multiple titratable infusions requires concentrated medications at low flows,rather than more dilute drugs at higher flows that in combination may volume overload small infants.AIM To determine whether carrier fluid reduces variability that variability of low flow drug infusions is proportional to syringe size in pediatric critical care.METHODS We assessed concentrations of orange“drug”in a 0.2 mL/h low flow clinical model with blue dyed carrier fluid at 5 mL/h,using 3-,10-,or 60-mL syringes.A graduated volumetric pipette was used to measure total flow.Mean time to target concentration was 30,21,and 46 min in 3-,10-,and 60-mL syringes,respectively(P=0.42).After achieving target concentration,more dilute drug was delivered by 60-mL(P<0.001)and 10-mL syringes(P=0.04)compared to 3-mL syringes.Drug overdoses were observed during the initial 45 min of infusion in 10-and 60-mL syringes.Total volumes infused after target concentration were less in the 60-mL condition compared to 3-mL(P<0.01)and 10-mL(P<0.001)syringes.RESULTS Linear mixed effects models demonstrated lesser delivered drug concentrations in the initial 30 min by 3-mL compared to 10-and 60-mL syringes(P=0.005 and P<0.001,respectively)but greater drug concentrations and total infused drug in the subsequent 30-60 and 60-90 min intervals with the 3-and 10-mL compared to 60-mL syringes.CONCLUSION With carrier fluid,larger syringes were associated with significantly less drug delivery,less total volume delivered,and other flow problems in our low flow drug model.Carrier fluid should not be used to compensate for inappropriately large syringes in critical low flow drug infusions.展开更多
胰腺癌是一种具有高度侵袭性的肿瘤,嗜神经生长是胰腺癌的重要生物学特点,其对神经的侵犯给患者带来极大的疼痛负担,严重影响患者生存质量和生存意志。世界卫生组织(World Health Organization,WHO)癌痛“三阶梯镇痛原则”是传统治疗癌...胰腺癌是一种具有高度侵袭性的肿瘤,嗜神经生长是胰腺癌的重要生物学特点,其对神经的侵犯给患者带来极大的疼痛负担,严重影响患者生存质量和生存意志。世界卫生组织(World Health Organization,WHO)癌痛“三阶梯镇痛原则”是传统治疗癌性疼痛的治疗方案,但由于其毒副作用明显、疗效差、易成瘾、易耐药以及医师临床用药不规范等因素,无法满足患者病情需要。近年来,随着介人技术的发展以及广泛的临床试验的开展,介入作为癌痛管理的“第四阶梯”,其治疗手段以及各种影像引导方式的发展与应用,如神经毁损术、^(125)I粒子植入术、患者自控镇痛泵技术、鞘内药物输注系统植入术等,临床疗效得到了有力证明,为癌痛患者提供了方便、安全、有效的治疗方式。展开更多
文摘Background: Elastomeric pumps (elastic balls into which analgesics or antibiotics can be inserted) push medicines through a catheter to a nerve or blood vessel. Since elastomeric pumps are small and need no power source, they fit easily into a pocket during infusion, allowing patient mobility. Elastomeric pumps are widely used and widely studied experimentally, but they have well-known problems, such as maintaining reliable flow rates and avoiding toxicity or other peak-and-trough effects. Objectives: Our research objective is to develop a realistic theoretical model of an elastomeric pump, analyze its flow rates, determine its toxicity conditions, and otherwise improve its operation. We believe this is the first such theoretical model of an elastomeric pump consisting of an elastic, medicine-filled ball attached to a horizontal catheter. Method: Our method is to model the system as a quasi-Poiseuille flow driven by the pressure drop generated by the elastic sphere. We construct an engineering model of the pressure exerted by an elastic sphere and match it to a solution of the one-dimensional radial Navier-Stokes equation that describes flow through a horizontal, cylindrical tube. Results: Our results are that the model accurately reproduces flow rates obtained in clinical studies. We also discover that the flow rate has an unavoidable maximum, which we call the “toxicity bump”, when the radius of the sphere approaches its terminal, unstretched value—an effect that has been observed experimentally. Conclusions: We conclude that by choosing the properties of an elastomeric pump, the toxicity bump can be restricted to less than 10% of the earlier, relatively constant flow rate. Our model also produces a relation between the length of time that the analgesic fluid infuses and the physical properties of the fluid, of the elastomeric sphere and the tube, and of the blood vessel into which the analgesic infuses. From these, we conclude that elastomeric pumps can be designed, using our simple model, to control infusion times while avoiding toxicity effects.
文摘AIM: To evaluate pain control in chronic pancreatitis patients who underwent total pancreatectomy with islet cell transplantation or intrathecal narcotic pump infusion.METHODS: We recognized 13 patients who underwent intrathecal narcotic pump(ITNP) infusion and 57 patients who underwent total pancreatectomy with autologous islet cell transplantation(TP + ICT) for chronic pancreatitis(CP) pain control between 1998 and 2008 at Indiana University Hospital. All patients had already failed multiple other modalities for pain control and the decision to proceed with either intervention was made at the discretion of the patients and their treating physicians. All patients were evaluated retrospectively using a questionnaire inquiring about their pain control(using a 0-10 pain scale), daily narcotic dose usage, and hospital admission days for pain control before each intervention and during their last follow-up. RESULTS: All 13 ITNP patients and 30 available TP + ICT patients were evaluated. The mean age was approximately 40 years in both groups. The median duration of pain before intervention was 6 years and 7 years in the ITNP and TP + ICT groups, respectively. The median pain score dropped from 8 to 2.5(on a scale of 0-10) in both groups on their last follow up. The median daily dose of narcotics also decreased from 393 mg equivalent of morphine sulfate to 8 mg in the ITNP group and from 300 mg to 40 mg in the TP + ICT group. No patient had diabetes mellitus(DM) before either procedure whereas 85% of those who underwent pancreatectomy were insulin dependent on their last evaluation despite ICT. CONCLUSION: ITNP and TP + ICT are comparable for pain control in patients with CP however with high incidence of DM among those who underwent TP + ICT. Prospective comparative studies and longer follow up are needed to better define treatment outcomes.
文摘Reliability of medical devices such as infusion pumps is extremely important because these devices are being used in patients who are in critical condition. Occlusion pressure, as an important parameter of infusion pumps, should be detected when an occlusion occurred. How-ever, infusion pumps’ occlusion pressure could not be tested and the performance of these pumps is not known to us. In order to test the occlusion pressure of infusion pump, a testing system has been put forward according to standards of IEC 60601-2-24:1998/ GB 9706.27- 2005. The system is comprised of sensor, acquisition card, three-way tap and so on;this system is controlled by a PC. At the same time, sampling rate could be changed if necessary and test time could be recorded. And then the characteristics of this system were studied, such as linear, effects of pump rates and different pumps. The system remained linear in a given environment. The higher is the pump rate, the faster is the time to reach occlusion condi-tion. The testing system has been proved to be effective in testing the occlusion pressure of infusion pumps and the accuracy error of pressure is content the demand of ±1% of range.
基金Supported by NIH National Center for Advancing Translational Sciences(NCATS)UCLA CTSI,No.UL1TR001881.
文摘BACKGROUND Critically ill neonates and pediatric patients commonly require multiple low flow infusions.Volume limitations are imposed by small body habitus and comorbidities like cardiopulmonary disease,renal failure,or fluid overload.Vascular access is limited by diminutive veins.Maintenance fluids or parenteral nutrition in conjunction with actively titrated infusions such as insulin,fentanyl,prostaglandins,inotropes and vasopressors may necessitate simultaneous infusions using a single lumen to maintain vascular catheter patency.This requirement for multiple titratable infusions requires concentrated medications at low flows,rather than more dilute drugs at higher flows that in combination may volume overload small infants.AIM To determine whether carrier fluid reduces variability that variability of low flow drug infusions is proportional to syringe size in pediatric critical care.METHODS We assessed concentrations of orange“drug”in a 0.2 mL/h low flow clinical model with blue dyed carrier fluid at 5 mL/h,using 3-,10-,or 60-mL syringes.A graduated volumetric pipette was used to measure total flow.Mean time to target concentration was 30,21,and 46 min in 3-,10-,and 60-mL syringes,respectively(P=0.42).After achieving target concentration,more dilute drug was delivered by 60-mL(P<0.001)and 10-mL syringes(P=0.04)compared to 3-mL syringes.Drug overdoses were observed during the initial 45 min of infusion in 10-and 60-mL syringes.Total volumes infused after target concentration were less in the 60-mL condition compared to 3-mL(P<0.01)and 10-mL(P<0.001)syringes.RESULTS Linear mixed effects models demonstrated lesser delivered drug concentrations in the initial 30 min by 3-mL compared to 10-and 60-mL syringes(P=0.005 and P<0.001,respectively)but greater drug concentrations and total infused drug in the subsequent 30-60 and 60-90 min intervals with the 3-and 10-mL compared to 60-mL syringes.CONCLUSION With carrier fluid,larger syringes were associated with significantly less drug delivery,less total volume delivered,and other flow problems in our low flow drug model.Carrier fluid should not be used to compensate for inappropriately large syringes in critical low flow drug infusions.
文摘胰腺癌是一种具有高度侵袭性的肿瘤,嗜神经生长是胰腺癌的重要生物学特点,其对神经的侵犯给患者带来极大的疼痛负担,严重影响患者生存质量和生存意志。世界卫生组织(World Health Organization,WHO)癌痛“三阶梯镇痛原则”是传统治疗癌性疼痛的治疗方案,但由于其毒副作用明显、疗效差、易成瘾、易耐药以及医师临床用药不规范等因素,无法满足患者病情需要。近年来,随着介人技术的发展以及广泛的临床试验的开展,介入作为癌痛管理的“第四阶梯”,其治疗手段以及各种影像引导方式的发展与应用,如神经毁损术、^(125)I粒子植入术、患者自控镇痛泵技术、鞘内药物输注系统植入术等,临床疗效得到了有力证明,为癌痛患者提供了方便、安全、有效的治疗方式。
