Simulating whole-body vibration for neonatal patients on a tire-coupled road simulator.

Exposure to excessive whole-body vibration is linked to health issues and may result in increased rates of mortality and morbidity in infants. Newborn infants requiring specialized treatment at neonatal intensive care units often require transportation by road ambulance to specialized care centers, exposing the infants to potentially harmful vibration and noise. A standardized Neonatal Patient Transport System (NPTS) has been deployed in Ontario, Canada, that provides life saving equipment to patients and safe operation for the clinical care staff. However, there is evidence that suggests patients may experience a higher amplitude of vibration at certain frequencies when compared with the vehicle vibration. In a multi-year collaborative project, we seek to create a standardized test procedure to evaluate the levels of vibration and the effectiveness of mitigation strategies. Previous studies have looked at laboratory vibration testing of a transport system or transport incubator and were limited to single degree of freedom excitation, neglecting the combined effects of rotational motion. This study considers laboratory testing of a full vehicle and patient transport system on an MTS Model 320 Tire-Coupled Road Simulator. The simulation of road profiles and discrete events on a tire-coupled road simulator allows for the evaluation of the vibration levels of the transport system and the exploration of mitigation strategies in a controlled setting. The tire-coupled simulator can excite six degrees-of-freedom motion of the transport system for vibration evaluation in three orthogonal directions including the contributions of the three rotational degrees of freedom. The vibration data measured on the transport system during the tire-coupled testing are compared to corresponding road test data to assess the accuracy of the vibration environment replication. Three runs of the same drive file were conducted during the laboratory testing, allowing the identification of anomalies and evaluation of the repeatability. The tire-coupled full vehicle testing revealed a high level of accuracy in re-creating the road sections and synthesized random profiles. The simulation of high amplitude discrete events, such as speed hump traverses, were highly repeatable, yet yielded less accurate results with respect to the peak amplitudes at the patient. The resulting accelerations collected at the input to the manikin (sensor located under the mattress) matched well between the real-world and road simulator. The sensors used during testing included series 3741B uni-axial and series 356A01 tri-axial accelerometers by PCB Piezotronics. These results indicate a tire-coupled road simulator can be used to accurately evaluate vibration levels and assess the benefits of future mitigation strategies in a controlled setting with a high level of repeatability.

Difficulty Using Smart Pump Logs to Recreate a Patient Safety Event: Case Study and Considerations for Pump Enhancements.

The authors present a case in which a physical anomaly with an infusion pump resulted in an unforeseen fault that the nurse's attempts to resolve unknowingly exacerbated. This case study presents the first report in the literature to detail the difficulty in recreating a patient safety event using smart pump logs, support server continuous quality improvement (CQI) data, and the drug order entry system to elucidate the clinical scenario. A 75-year-old male patient presented to a major teaching hospital and was admitted to the intensive care unit (ICU) with a massive gastrointestinal bleed and myocardial infarction, then stabilized. One of the patient's pumps alarmed "communication error" on the display. The display gave no explicit instructions about how to resolve the issue, and resolution was not intuitive. Attempts to clear the alarm failed, so the module was disconnected to reprogram the infusion, causing an interruption in the dopamine. Over the course of approximately 2 min of troubleshooting, the patient's blood pressure decreased from 109/50 to 60/30, with a rapid pulse change from a consistent 95 up to 115 and subsequently 135 beats per minute. A cardiac arrest ensued and a code blue was called. All cardiac drugs, including the dopamine, were suspended during the code. Cardiopulmonary resuscitation was performed and the patient survived the code. Post-code, the dopamine and epinephrine were restarted, and the norepinephrine was discontinued. The patient's condition remained very unstable. Pump logs and the server database were queried to locate relevant equipment. It was concluded that dirty contacts on the inter-unit interface (IUI) connectors between the PC unit (PCU) and the modules caused the alarm message "communication error" to appear on the PCU display. Learning yielded a nursing practice alert to clarify how a nurse should resolve a "communication error", and appropriate cleaning protocols were promptly implemented. The investigation found smart pump event logs and proprietary software are not designed with any forethought as to retrospective reconstruction of incident investigations, leaving facilities to cobble together pieces of information from multiple sources to determine what occurred. The authors also suggest further pump enhancements, challenging pump manufacturers to go to the next level of integration and enable greater patient safety with smart infusion pumps.

Inadvertent overinfusion of norepinephrine using infusion pump loading dose.

Programming infusion pumps has been recognised as a high-risk step and a source of adverse events (Nuckols et al., 2008; Hyman, 2010). Literature describing infusion pump loading dose errors and NORepinephrine complications is scarce (Girard et al., 2010). This case study presents the first ever report of an inadvertent overinfusion of NORepinephrine due to the loading dose option on the infusion pump, and resulting cardiac arrest of the patient. A patient was admitted to the emergency room and started on a NORepinephrine infusion inadvertently as a loading dose rather than a primary infusion. Historical values for the loading dose volume to be infused (VTBI) and primary rate were not adjusted during the setup. Eight hours and 58minutes later, the loading dose VTBI reached 0mL and the pump reverted to the historical primary rate of 999mL/hour. The event log showed that 37.1mL of NORepinephrine was infused resulting in an equivalent calculated bolus dose of 1.8mg administered in two minutes. The patient suffered a cardiac arrest and the infusion was stopped. No faults were found with the pump. Herein, we discuss our analysis of the pump event logs and propose further safety strategies and interventions.

Thrombosis and failure of a HeartMate II device in the absence of alarms.

Next-generation left ventricular assist devices such as the HeartMate II (Thoratec Corporation, Pleasanton, CA) have significantly improved patient outcomes. In particular, the incidence of thromboembolic events appears to be significantly reduced. Pump thrombosis has occurred, however, and is well reported in the literature. The thromboses reported with next-generation devices have generally been partial thromboses associated with significant abnormalities in the system performance data as displayed on the system monitor. We describe a case of complete thrombosis of a HeartMate II axial-flow pump resulting in cardiac arrest but in the absence of alarms or significant aberrations in the performance data.