Carlo Alberto Lodi

Multidisciplinary Evaluation for Severity of Hazards Applied to Hemodialysis Devices: An Original Risk Analysis Method

BACKGROUND AND OBJECTIVESnRisk analysis for medical devices is a crucial process to grant adequate levels of safety. Identification of device exposure-related hazards is one of the main objectives.nnnDESIGN, SETTING, PARTICIPANTS, & MEASUREMENTSnHazard analysis for hemodialysis devices has been performed by a multidisciplinary team involving engineers and clinical experts. A potential harm list was identified from clinical and technical experience, postproduction information, and literature. Various hazardous situations (circumstances when the use of the dialysis device may lead to described harms) were described. Such hazardous situations were correlated to the extent of the deviation of a specific device parameter from expected ranges. The clinical severity that was relevant to any specific harm was categorized for each hazardous situation using a descriptive and numerical scale with five levels (from negligible [i.e., discomfort only] to catastrophic [i.e., potentially lethal]).nnnRESULTSnHarms in which the deviation of a parameter strictly coincides with the clinically measured effect on the patient are defined as direct. Otherwise, when another clinical parameter must be involved to quantify severity, the related harm is considered indirect. Two complete examples of multidisciplinary evaluation for severity of hazards (MESH) are given for a direct harm (air embolism) and for an indirect harm (hypothermia). For other harms, the maximum value of severity involved is provided.nnnCONCLUSIONSnMESH represents a possible example of risk management for dialysis equipment in which, although the manufacturer is directly responsible, a multidisciplinary task force may contribute to a better link between engineering and clinical perspectives.

In Vitro Comparative Assessment of Mechanical Blood Damage Induced by Different Hemodialysis Treatments

Abstract Gradual deterioration of red blood cells (RBCs) due to mechanical stress (chronic hemolysis) is unavoidable during treatments that involve extracorporeal blood circulation, such as hemodialysis (HD). This effect is generally undetectable and does not generate any acute symptoms, but it leads to an increase in plasma free hemoglobin (fHb). There are no absolute safety levels for fHb increase, indicating the need for an empirical evaluation using comparative testing. The increase in fHb levels was investigated in vitro by applying double‐needle double‐pump HD (HD‐DNDP), a new modality in which arterial and venous pumps both run continuously. fHb was measured during typical and worst‐case simulated dialysis treatments (double‐needle single‐pump HD [HD‐DNSP], hemodiafiltration [HDF‐DN], single‐needle double‐pump HD [HD‐SNDP], and HD‐DNDP) performed in vitro using bovine blood for 4u2009h. Hemolysis‐related indices (fHb%; index of hemolysis, IH; and normalized IH) were calculated and used for comparison. The increase in fHb during either HDF‐DN or HD‐SNDP with Artis and AK200 dialysis machines was similar, while the fHb at the maximum real blood flow rate (Qbreal) at the completion of the HD‐DNDP treatment on Artis was higher than that for HD‐DNSP using a Phoenix dialysis machine (fHb %u2009=u20091.24u2009±u20090.13 and 0.92u2009±u20090.12 for the Artis machine with HD‐DNDP at Qbrealu2009=u2009450u2009mL/min and Phoenix with HD‐DNSP at Qbrealu2009=u2009500u2009mL/min, respectively). However, the fHb levels increased linearly, and no steep changes were observed. The increases observed during HD‐DNDP were the same order of magnitude as those for widely used bloodlines and treatment modes for delivering dialysis treatments. The observed results matched literature findings, and thus the measured fHb trends are not predicted to have clinical side effects. HD‐DNDP treatment with Artis does not merit any additional concern regarding mechanical stress to RBCs compared with that observed for routinely used dialysis treatments, bloodlines and machines. Although the in vitro measurement of the fHb increase in bovine blood does not allow a prediction of the absolute level of blood mechanical damage or the possible effects in humans, such measurements are valuable for assessing hemolytic harm by performing tests comparing the proposed treatment with existing devices.