Summary: Risks associated with conventional humidifiers adapted for high-flow nasal cannula therapy in human infants: Results of a time and motion study.
Tero R, Cecich J, Sanabria O, et al. Risks associated with conventional humidifiers adapted for high-flow nasal cannula therapy in human infants: Results of a time and motion study. Int J Clin Pediatr. 2014;3(4)-99-104. doi: http://dx.doi.org/10.14740/ijcp172w
Tero and colleagues evaluated workflow on high-flow nasal cannula (HFNC) devices at 3 different institutions during 8-hour observations periods in which staff self-reported device interactions. The workflow parameters included clearing condensate, need for suctioning, interface/tubing changes and charting. Device-related events that impacted workflow included the incidence of water in the airway, irritation, and clinical sequelae.
The authors describe the task of humidifying dry, cool respiratory gas to body temperature, and then delivering that gas to the patient without significant loss of energy and subsequent rainout is a challenge for humidification devices. Conventional technologies are prone to rainout, requiring staff to routinely disconnect and drain condensate from the circuitry. Condensation management is particularly important for HFNC therapy as all of the gas travels through the cannula into the spontaneously breathing patient’s nose, without any circuit bias flow that bypasses the patient.
The study was conducted at three separate institutions: one center used both device platforms; one center used the Fisher &Paykel (FP) device, and one center used the Vapotherm (VT) device. All staff, respiratory therapists(RTs), nurses, and physicians as indicated, were instructed to list device-related interactions during the study period, i.e., workflow related to management of the device or a function of device technical performance. A total of 48 FP observations and 61 VT observations were collected. FP showed more therapist interventions (4.5 ± 1.5 vs. 1.5 ± 0.6; P < 0.001), and total unscheduled interventions (1.1 ± 1.6 vs. 0.3 ± 0.7; P < 0.001) compared to VT. Of the interventions, FP required draining tubing 2.1 ± 1.0 times vs. 0 ± 0 with VT (P < 0.001). Rainout aspiration from the FP was associated with the 0.7 ± 1.5 device-related clinical events, versus 0 ± 0 events seen with VT (P < 0.001).
The authors note that a major impact of the study was that it revealed clinical risk associated with the management of rainout in the use of the adapted conventional technology. The data demonstrate that condensed water accumulating in conventional circuitry is a real concern that requires a significant staff awareness and effort to mitigate the risk. Therefore, in choosing to use the adapted conventional technology over the purpose-built HFNC platform, administrators should consider the staffing and resource needs to manage this phenomenon weighted against the risk and potential cost of adverse events.
Aside from the risk of patient aspiration, the authors show how rainout in the patient circuit presents a complex challenge for management. Rainout in the tubing is routinely dumped back into the reservoir to avoid discontinuation of therapy by breaking the circuit to drain. However, American Association for Respiratory Care clinical practice guidelines for humidification systems with invasive and noninvasive ventilation (2012) considers circuit condensation to be infectious waste (Section 12.3), which should “never be drained back into the humidifier reservoir” (Section 12.4)1.
The study limitations are such that the devices were not randomly selected for inclusion in the observations. However, all devices should function to the manufacturers’ specifications and therefore randomization should not be warranted. The self-report methodology has limitations with respect to accuracy of time spent for each device contact; however, this methodology was used in place of an observer model because of the challenges of controlling intra-observer error across three centers. Moreover, the model used here was not able to capture the time and effort spent outside of routine patient care for the planning and implementation of strategies to mitigate circuit rainout, such as localization of patient beds relative to air vents, etc.
In conclusion, as compared to the purpose-built platform, HFNC with an adapted conventional humidifier was associated with a significant increase in staff contacts and the potential for patient risk related to the management of rainout. Thus, there is an unaccounted cost beyond circuit price with the use of conventional technologies for the administration of HFNC. When using conventional humidification technology, consideration should be given to the cost of staffing and resources needed to manage circuit rainout and account the risk of clinical sequelae associated with condensate aspiration.
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