The indications for home mechanical ventilation. Evaluation of the user-friendliness of 11 home mechanical ventilators

Transcription

1 Eur Repir J 26; 27: DOI: / CopyrightßERS Journal Ltd 26 Evaluation of the uer-friendline of 11 home mechanical ventilator J. Gonzalez-Bermejo*, V. Laplanche*, F.E. Hueini #, A. Duguet*, J-P. Derenne*,# and T. Similowki*,# ABSTRACT: The home ventilator market ha grown in ize and complexity. The aim of thi tudy wa to determine if common home ventilator are uer-friendly for trained intenive care unit (ICU) phyician. Eleven ventilator model were teted by 13 ICU phyician without practical experience in home mechanical ventilation. Six tet were defined (tart-up, unlocking, mode and etting recognition, mode change, preure etting and alarm). For each tet, the phyician were timed and their performance compared with a reference time etablihed by a technician. The phyician alo had to rate their global aement of each machine on a viual analogue cale. The tart-up tet wa the only tet for which there wa no ignificant difference between the phyician and the technician, except for two ventilator. The phyician were lower than the technician to unlock the ventilator and change the ventilatory mode, with ome complete failure during thee tet and heterogeneou reult between phyician and between ventilator. Mitake occurred in cloe to 5% of cae during the ventilatory mode and etting recognition tet. The mean time for the mot rapid of the phyician for all the tet wa 58 53, compared with 15 9 for the technician. In concluion, trained intenive care unit phyician perform poorly when confronted with home mechanical ventilator without pecific prior training. Therefore, it i hypotheied that the uerfriendline of home ventilator for other categorie of uer might be quetionable. KEYWORDS: Home care, international tandardiation office, mechanical ventilation, ventilator The indication for home mechanical ventilation are numerou in both adult and children [1]. Development in deign and technology ince 1996 have led to coniderable improvement in the mechanical ventilator available to phyician and patient for home ue. In the pat, the very limited number of model available only permitted controlled ventilation with very few etting poible, and only baic monitoring. There are now.3 model on the market, with each providing everal ventilation mode and offering numerou option for etting. However, no common nomenclature exit (table 1). Thi diverity introduce flexibility and alo complexity, thu involving the rik that medical and paramedical peronnel reponible for the care of patient uing home ventilation may not be able to properly manage the technical apect. Thi rik i particularly worrying when urgent or emi-urgent reaction to a ituation i required, in the knowledge that the peronnel involved i more unlikely than likely to Thi article ha upplementary data acceible from have previou familiarity with home mechanical ventilator. It i probably deirable that any phyician dealing with a patient on home mechanical ventilation hould be able to eaily recognie the ventilation mode adminitered, undertand the ource of alarm or malfunction without alarm, and take imple rapid meaure for the patient afety. Thi i particularly important in patient who are ventilator dependent or nearly o, a population that i of growing importance in the home ventilation etting. Variou factor contribute to making uch expectation unrealitic. There are very few training programme in home mechanical ventilation for phyician and caregiver [2]. Manufacturer of home ventilator are familiar with technological bench-tet aement [3 5] and are, however, unable to eaily evaluate the uer interface of the machine they develop. When they do, they uually turn to phyician experienced in the ue of home mechanical ventilator, thu biaing the finding. Paradoxically, there are no AFFILIATIONS *Aitance Publique-Hôpitaux de Pari, Service de Pneumologie et de Réanimation, Groupe Hopitalier Pitié-Salpêtrière, # Univerité Pari VI Pierre et Marie Curie, Unité Propre de Recherche de l Eneignement Supérieure EA 2397, Pari, and " Centre d Aitance Repiratoire à Domicile d Ile-de-France, Fontenayaux-Roe, France. CORRESPONDENCE T. Similowki Service de Pneumologie et de Réanimation Groupe Hopitalier Pitié-Salpêtrière Aitance Publique-Hôpitaux de Pari Bd de l Hôpital Pari Cedex 13 France Fax: thoma.imilowki@pl.aphop-pari.fr Received: July 6 25 Accepted after reviion: February 2 26 SUPPORT STATEMENT Thi tudy wa upported in part by the Aociation pour le Développement et l Organiation de la Recherche en Pneumologie (Pari, France), and by the Centre d Aitance Repiratoire à Domicile d Ile-de-France (Fontenay-aux- Roe, France). European Repiratory Journal Print ISSN Online ISSN VOLUME 27 NUMBER 6 EUROPEAN RESPIRATORY JOURNAL

2 J. GONZALEZ-BERMEJO ET AL. USER-FRIENDLINESS OF HOME VENTILATORS marketing regulation for ventilator. Thi leave manufacturer free to offer novel control panel and chooe the name given to the ventilation mode they provide (to the extent that an identical mode can have everal name), and o on. An overview of the home mechanical ventilator market give the general impreion that there i no homogeneity; combination of button are frequently required to tart or top a function, the labelling of button i not very clear, and control creen tend to be too mall and difficult to read. Depite thi obervation, no publihed data eem to exit that would convert thi impreion into finding, and thu prompt manufacturer to concentrate their effort on deigning ufficiently imple machine-uer interface to guarantee afe quality care. In thi context, the objective of the current tudy wa to evaluate the uer-friendline of the 11 home mechanical ventilator mot frequently ued in France for trained intenive care unit (ICU) phyician. MATERIAL AND METHODS Ventilator Eleven ventilator model were teted, in accordance with the following lit: Eole 3 XLS1 (Saime, Savigny le Temple, France), Hélia 2 (Saime), Onyx plu1 (Tyco, Saint Loui, MO, USA), VPAP III1 (ReMed, North Ryde, NSW, Autralia), BiPAP Synchrony1 (Repironic, Murryville, PA, USA), Smartair PLUS1 (Airox, Pau, France), VS Ultra1 (Saime), Nefti1 (Taema, Anthony, France), Knighttar1 (Tyco), PV 31 (Brea Medical, Mölnlyche, Sweden) and Légendair1 (Airox). Each ventilator wa connected to a 2-L tet bag while tet were being performed. Phyician Thirteen phyician with ound experience in mechanical ventilation in the context of intenive care, but without practical experience in home mechanical ventilation, participated in the tudy (five pecialit in repiratory medicine, five pecialit in intenive care, two neurologit, one anaethetit), all qualifying a enior ICU phyician although with variou degree of experience due to an age range of yr. Only one of the 13 ICU phyician had been in contact with the Onyx plu1 ventilator before, two had previou contact with the Helia 21 (Saime, Savigny le Temple, France), three with the VS Ultra1, and one with the Légendair1. In all of thee cae, the participant did not conider themelve familiar with the ventilator. The ituation wa lightly different for Eole 3 XLS1, which even of the participant already knew with ome degree of familiarity. Tet Six tet were defined. Each tet wa explained to the phyician; the examiner gave the tarting ignal and timing wa either topped a oon a the objective fixed had been achieved, or at the arbitrarily decided limit of 3 min. Each phyician performed the ix tet conecutively for the pecified ventilator, but the order in which the ventilator were evaluated wa randomied. The tet lit wa a follow. TABLE 1 Ventilator Ventilation mode upplied by the variou ventilator teted, uing the name devied by the manufacturer Name of mode (French abbreviation) Eole 3 XLS1 (Saime, Savigny le Temple, France) Helia 21 (Saime) Knighttar1 (Tyco, Saint Loui, MO, USA) Légendair1 (Airox, Pau, France) Nefti1 (Taema, Anthony, France) Onyx plu1 (Tyco) PV 31 (Brea Medical, Mölnlyche, Sweden) Smartair PLUS1 (Airox) BiPAP Synchrony1 (Repironic, Murryville, PA, USA) VPAP III1 (ReMed, North Ryde, NSW, Autralia) VS Ultra1 (Saime) VAC, VC, RPr, VACI VS, AI, VPC, VPAC, RPr, AI.Vt, VC, VAC CPAP, I/E, A/C PPC, AI, AI.fr, VPC, VPAC VSAI, VC, VAC, PC, PAC, VACI VSAI, VPAC, VAC AI, VPC, VVC PPC, AI, AI.fr, VPC, VPAC S, ST, T 1, PPC, AVAPS S, S/T, T 2,CP S, ST, PAC, AI, VPAC, AI.Vt, VAC For each mode, the meaning of the French abbreviation i indicated below, followed by a literal Englih tranlation in quare bracket (thu not necearily correponding to the Englih term for the ventilation mode). VAC: ventilation aitée contrôlée [ait-control ventilation]; VC: ventilation contrôlée [controlled ventilation]; RPr: relaxateur de preion [preure relaxation]; VACI: ventilation aitée-contrôlée intermittente [intermittent ait-control ventilation]; VS: ventilation pontanée [pontaneou ventilation]; AI: aide inpiratoire avec ou an fréquence de écurité [inpiratory preure upport (with or without minimal frequency)]; VPC: ventilation en preion contrôlée [preure control ventilation]; VPAC: ventilation en preion aitée contrôlée [ait-control preure upport ventilation]; AI.Vt: aide inpiratoire avec fréquence garantie [preure upport with guaranteed tidal volume]; CPAP: preion contante (Knighttar1) [contant preure]; I/E: 2 niveaux de preion (Knighttar1) [two preure level]; A/C: 2 niveaux de preion avec fréquence minimale (Knighttar1) [two preure level with minimal frequency]; PPC: poitive preion continue [continuou poitive preure]; AI.fr: aide inpiratoire avec fréquence guarantie [preure upport with guaranteed repiratory frequency]; VSAI: ventilation pontanée avec aide inpiratoire [pontaneou ventilation with preure upport]; PC: preion contante (BiPAP Synchrony1) [contant preure]; PAC: preion aitée contrôlée [ait-control preure upport]; VSAI: ventilation pontanée avec aide inpiratorie [pontaneou ventilation with preure upport]; VVC: ventilation à volume contrôlé [volume-controlled ventilation]; S: pontanée [pontaneou]; ST: pontanée avec fréquence minimale (VS Ultra1) [pontanou with minimal frequency]; T 1 : 2 niveaux de preion contrôlée (BiPAP Synchrony1) [two-level preure control]; AVAPS: fonction d aitance de preion aure elon un volume moyen (n et pa un mode ventilatoire en tant que tel) [preure upport with minimal mean volume (not a ventilation mode a uch)]; S/T: pontané/temporié (VPAP III1) [pontaneou with temporiation]; T 2 : temporié (VPAP III1) [temporied]; CP: mode de commande de preion [preure command]. c EUROPEAN RESPIRATORY JOURNAL VOLUME 27 NUMBER

3 USER-FRIENDLINESS OF HOME VENTILATORS J. GONZALEZ-BERMEJO ET AL. TABLE 2 Score given to ventilator by phyician after completing the tet Ventilator Score # Eole 3 XLS (2.5 9) Helia ( 7.5) Knighttar ( 3) Légendair (2 7) Nefti ( 9) Onyx plu ( ) PV ( 5.5) Smartair PLUS ( 4.5) BiPAP Synchrony ( 6) VPAP III ( 5.5) VS Ultra (3 8) Data are preented a mean SD (range). # :5difficult to ue; 1 5 eay to ue. See table 1 for manufacture datail of the ventilator. Tet 1: Start-up With the ventilator completely aembled and connected to the power upply, the phyician had to tart the ventilator; the top ignal wa given at the firt inufflation produced by the ventilator. Tet 2: Unlocking The International Organization for Standardization (ISO) tandard [6, 7] tipulate that there mut be a afety mechanim to prevent any accidental adjutment of control on a mechanical ventilator intalled at the home of a patient; a phyician wanting to change any ventilation etting mut firt diable thi afety mechanim. However, the tandard doe not provide any information on what thi afety mechanim hould be; home mechanical ventilator manufacturer have adopted very different olution. Tet 2 required phyician to unlock a previouly tarted ventilator, without conulting the operating manual. The top ignal wa given a oon a the phyician had actual acce to ventilator etting. Tet 3: Recognition Thi tet required phyician, with a ventilator that wa turned on and upplying a given ventilation mode, to fill in a chart identifying the ventilation mode and the main preet parameter, which were tidal volume (VT) and breathing frequency (f) in volume-controlled mode, and inpiratory preure upport and poitive end-expiratory preure in preurecontrolled mode. The ventilator mode were a follow. Onyx plu1: ventilation pontanée avec aide inpiratoire [pontaneou ventilation with preure upport] (VSAI); Légendair1, ventilation en preion contrôlée [preure control ventilation] (VPC); Nefti1: ventilation aitée contrôlée [ait-control ventilation] (VAC); PV 31: aide inpiratoire avec ou an fréquence de écurité [inpiratory preure upport (with or without minimal frequency)] (AI); BiPAP Synchrony1: pontané/temporié (VPAP III1) [pontaneou with temporiation] (S/T); Knighttar1: 2 niveaux de preion avec fréquence minimale [two preure level with minimal frequency] (A/C); Smartair PLUS1: aide inpiratoire avec fréquence repiratoire de écurité [inpiratory preure upport with ecurity frequency] (Aifr); VPAP III1: S/T; VS Ultra1: aide inpiratoire avec volume auré [inpiratory preure upport with minimal volume] (AIVt); Eole 3 XLS1: ventilation aitée contrôlée [ait-control ventilation] (VAC); and Helia 21: AIVt (table 2). The top ignal wa given a oon a the chart wa filled in. 4) Mode change Starting with a ventilator preet to upply preure upport ventilation and unlocked, the phyician had to change to volume-controlled mode and adjut VT and f to predefined value. The top ignal wa given a oon a the firt inufflation wa achieved with the required etting. Thi tet only concerned mixed type ventilator providing the poibility of both preure- and volume-controlled ventilation (VS Ultra1, Helia 21, Légendair1 and Nefti1). 5) Preure etting Starting with a preet and unlocked ventilator, the phyician had to et a precie level of inpiratory preure upport. The top ignal wa given a oon a the firt inufflation wa achieved with the required etting. Thi tet only concerned ventilator providing preure-controlled ventilation (Knighttar1, VPAP III1, BiPAP Synchrony1, Smartair PLUS1 and Onyx plu1). 6) Alarm Starting with a preet and unlocked ventilator, the phyician had to adjut alarm (high preure, low preure and apnoea) to predefined value. The top ignal wa given a oon a the alarm value had been adjuted to the required level. Thi tet naturally only concerned ventilator equipped with alarm (Légendair1, Eole 3 XLS1 and VS Ultra1) Evaluation For each tet, the time taken by the phyician wa compared with a reference time etablihed by a technician from the Comité d Aitance Repiratoire à Domicile d Ile-de-France (CARDIF; Pari Region Committee for Home Repiratory Aitance, Pari, France) with thorough knowledge of the ventilator teted. Moreover, once all the tet were completed for a given ventilator, the phyician had to rate their aement on a viual analogue cale along a 1-cm line marked with () on the left for very difficult to ue, and (1) on the right for very eay to ue. Statitical analyi For each of the ix tet performed, variance analyi wa carried out uing a phyician factor (including the reult of the 13 phyician and thoe of the technician), and a ventilator factor. Comparion of the phyician reult with thoe of the technician wa performed uing a pot hoc Dunnett tet. Comparion of reult between phyician and comparion of ventilator wa performed uing a Tukey tet. For all comparion, the ignificance threhold wa fixed at the value of p.5. The reult were expreed in the form of mean SD. RESULTS Overall reult Figure 1 how the mean reult obtained by the phyician (for all the tet on all the ventilator) compared with the 1238 VOLUME 27 NUMBER 6 EUROPEAN RESPIRATORY JOURNAL

4 J. GONZALEZ-BERMEJO ET AL. USER-FRIENDLINESS OF HOME VENTILATORS Time FIGURE 1. Mean time for performing all the tet on all the ventilator by phyician (h) and the technician (&). There were no ignificant difference between phyician, but all phyician time were ignificantly longer than the technician time (fp5.1). 3) Recognition Eight phyician out of 13 proved to be ignificantly lower than the technician in thi tet. For the remaining five, the difference wa not ignificant, but the phyician time were 2 3 time that of the technician (24 on average for the latter, for the phyician). Moreover, the anwer given by the phyician proved to be erroneou on at leat one point in 49% of the cae (fig. 4; wrong mode: 13%; wrong frequency: 1%; confuion between inpiratory preure upport and inter- Time technician. The mean time (mean SD (range)) for the mot rapid of the phyician for wa (5 18), compared with 15 9 (6 27) for the technician. 2 Table 2 how the core concerning ventilator uer-friendline given by the phyician after completing the tet. None of the difference reached the tatitical ignificance threhold. Knighttar Nefti PV3 Hélia 2 Eole 3 XLS Reult by tet 1) Start up The ventilator were tarted in 17 1 for the mot rapid of the phyician, veru 13 6 [6 27] for the technician. There were no ignificant difference between phyician and the technician or between the phyician. The ventilator were ditributed in two group within which there were no difference, but between which there wa a ignificant difference. In fact, two ventilator, the Nefti1 (61 22 ) [29 135] and the Knighttar1 (7 61 )[12 65], required ignificantly more time to tart than the other nine (p,.1). Reult are hown in figure 2. 2) Unlocking On average, two phyician out of 13 did not take ignificantly longer than the technician to unlock the 11 ventilator, depite difference that could have a clinical impact (12 on average for the technician, againt 49 and 59 on average for the other two phyician). The 11 other phyician were ignificantly lower than the technician in the procedure for unlocking ventilator etting. Concerning the ventilator, the Eole 3 XLS1 proved to be ignificantly quicker to unlock than the other model (31 17 (12 66) ). The BiPAP Synchrony1 and Knighttar1 model proved to be ignificantly longer to unlock that the other machine ( (32 18) and (73 18), repectively, p,.1). No phyician ucceeded in unlocking the VPAP III1 ventilator in the allotted time limit of 3 min. Reult are hown in figure 3. Setting for the Knighttar1 ventilator took tatitically longer to analye than the other (p5.1), which were evenly ditributed in two homogeneou group (51 7 and 8 11 ). FIGURE 2. Timing reult for tet 1 (tart-up). The graph how the time required to uccefully perform the tet for each of the 11 ventilator teted. For each ventilator, the box correpond to the 75th percentile of the data ditribution with indication of the median, wherea the whiker indicate the 9th percentile. m: the reference time etablihed by the technician Time Knighttar Nefti PV3 Hélia 2 Eole3 XLS FIGURE 3. Timing reult for tet 2 (unlocking). The graph how the time required to uccefully perform the tet for each of the ventilator teted. For each ventilator, the box correpond to the 75th percentile of the data ditribution with indication of the median, wherea the whiker indicate the 9th percentile. m: the reference time etablihed by the technician. c EUROPEAN RESPIRATORY JOURNAL VOLUME 27 NUMBER

5 USER-FRIENDLINESS OF HOME VENTILATORS J. GONZALEZ-BERMEJO ET AL Time Knighttar Nefti PV3 Hélia Eole3 XLS FIGURE 4. Reult of tet 3 recognition of mode and etting. h: adequate recognition; &: no recognition; F: confuion between et value and meaured value; &: confuion between inpiratory preure upport and intermittent poitive airway preure; &: wrong frequency; &: wrong mode. mittent poitive airway preure: 21%; confuion between the et value of a given variable and it meaured value: 12%; no recognition at all: 2%). Reult are hown in figure 5. 4) Mode change Seven phyician were ignificantly lower than the technician for thi tet, but only one phyician wa ignificantly lower than the other (124 7 (7 18) veru (12 48), p5.4). The Helia 21 ventilator wa markedly different from the other, a only one of the phyician ucceeded in changing to volume-controlled mode (concealed function). Reult are hown in figure 6. 5) Preure etting Six out of the 13 phyician were ignificantly lower than the technician in thi tet. They were ditributed in two homogeneou group within which there were no difference (a group of three phyician timed at , and for the other group). The tet wa carried out ignificantly fater on the Smartair PLUS1 ventilator (mean 56 ) than the other ventilator that underwent thi tet ( ). Reult are hown in figure 7. 6) Alarm Again, in thi tet, ix out of the 13 phyician proved to be ignificantly lower than the technician. There were no difference between the ventilator. Reult are hown in figure 8. DISCUSSION The preent tudy, which i apparently one of the firt of thi type, brought out both poitive and negative element. On the poitive ide, it wa noted that a variable proportion of phyician participating in the tudy were able, without previou training, to equal the performance of a technician experienced in the ue of home mechanical ventilator. On the FIGURE 5. Timing reult for tet 3 (recognition). The graph repreent the time required to uccefully perform the tet for each of the 11 ventilator teted. For each ventilator, the box correpond to the 75th percentile of the data ditribution with indication of the median, wherea the whiker indicate the 9th percentile. m: the reference time etablihed by the technician. negative ide, the revere wa true, and phyician were often lower that the trained technician. It hould be emphaied that, even though difference in timing did not reach the tatitically ignificant threhold, the phyician were ometime very low in comparion with the reference tet. The reult of the unlocking tet, recognition tet (49% error, fig. 4) and etting tet (mean value of four time the time taken by the technician) are caue for concern. It wa alo noted that there were ome more pecific problem, uch a the impoibility for all the phyician but one to acce the change to volume mode on one of the machine teted. All thee point reult in a quite mediocre overall core (table 2), although it i granted that the lack of ignificant difference between ventilator could be due to an inufficient tatitical power. Poible limitation to the tudy The objective of the current tudy wa not to decribe the full extent of the difficultie that patient, and their familie and caregiver, receiving home mechanical ventilation can be faced with. Rather, from the preent author experience, it wa felt that attention mut be brought to the blatant lack of uerfriendline of home ventilator. For thi reaon, the preent tudy wa retricted to ICU phyician unaware of the pecific of home ventilation, but well accutomed to the ue of variou type of mechanical ventilator and alo accutomed to managing ome ventilator depite having little background about their particular type. The preent tudy reveal nothing about the eae of ue of the ventilator for more ordinary conumer. Neverthele, the difficultie encountered by ICU phyician (who hould repreent the profeional category with both the highet and the mot homogeneou kill in mechanical ventilation) make the chance light that other unprepared phyician or caregiver called in to provide care for home-ventilated patient will be at eae with the home 12 VOLUME 27 NUMBER 6 EUROPEAN RESPIRATORY JOURNAL

6 J. GONZALEZ-BERMEJO ET AL. USER-FRIENDLINESS OF HOME VENTILATORS Time Time Knighttar Nefti PV3 Hélia 2 Eole3 XLS Knighttar Nefti PV3 Hélia 2 Eole3 XLS FIGURE 6. Timing reult for tet 4 (mode change). The graph how the time required to uccefully perform the tet for each of the ventilator teted. For each ventilator, the box correpond to the 75th percentile of the data ditribution with indication of the median, wherea the whiker indicate the 9th percentile. m: the reference time etablihed by the technician. FIGURE 7. Timing reult for tet 5 (preure etting). The graph how the time required to uccefully perform the tet for each of the ventilator teted. For each ventilator, the box correpond to the 75th percentile of the data ditribution with indication of the median, wherea the whiker indicate the 9th percentile. m: the reference time etablihed by the technician. ventilator. It i noteworthy that the urvey wa deliberately not conducted with phyician experienced in home mechanical ventilation. In all likelihood, they would have obtained reult cloer to thoe of the technician who etablihed the reference time, but it would have been difficult to objectify what their experience actually wa, and, thu, to contitute a homogeneou group. Phyician were alo avoided who had no experience of artificial ventilation, a thi would have created the oppoite bia. Similar tudie involving other profeional categorie would be intereting. Some of the participant in the tudy had ome prior knowledge of ome of the ventilator teted (ee Method). Thi did not influence the reult, except perhap for the Eole 3 XLS1 ventilator, which wa the bet known of the 13 model teted: thi may explain why it wa the fatet ventilator to unlock during tet 2. The technician who etablihed the reference time wa highly trained, and perhap thee reference time were unreaonably hort. Neverthele, while it i not urpriing that unfamiliaried phyician would take longer than a trained technician to perform the tet, ome of the recorded difference are huge, and the important variability among phyician mut be noted. In addition, the performance of the ICU phyician wa poor, not only in relation to the reference time, with timeindependent recognition error and many complete failure to perform ome of the tet. Not having given any training to the phyician before the tet could alo be criticied, but thi appeared to be the bet poible tandardiation, and doe in fact correpond to many real-life ituation. Finally, on method, the range of ventilator teted in thi tudy doe not repreent all the available machine. However, it doe correpond to the machine mot often ued in France, and i varied in term of brand and model. From thi point of view, the preent tudy i repreentative of poible clinical ituation. Start-up and unlock procedure Even though all the phyician had taken longer than the reference time to tart the ventilator, the reult of tet 1 can be conidered to be atifactory. The only two ventilator that proved to be more difficult to tart were unlike the other. In one cae, it wa the poition of the on/off button (Knighttar1: on the ide of the machine intead of the front panel); in the other cae, it wa the type of operation required to activate the button (Nefti1: brief intead of prolonged preure). Even though it can appear to be a trivial point, thi ugget that the ventilator on/off button hould be ytematically placed on the front panel of the machine, and hould be operated by preure ufficiently long enough to meet the ISO tandard afety requirement (i.e. mean hall be provided to prevent accidental operation of the on/off witch [6, 7]), but without impoing a time limit. The ISO tandard in force [6, 7] recommend the preence of a mean of protection againt inadvertent adjutment of control that can create a hazardou output (involving rik). The tandard doe not pecify whether the aim of thee mean i to avoid accidental adjutment, or to avoid acce to adjutment by patient and their familie. However, it i obviou that the recommendation i directed at the firt and not the econd cae, a the unlocking procedure are in the ventilator operating manual and can be found by trial and error. Patient who want to modify the etting of their ventilator for ome reaon or other will alway find a way. In thi context, the reult of tet 2 provide a good indication of a real problem: the mean unlocking time greatly exceeded the reference time, and a certain number of failure were recorded (ytematically for one of the machine). Two phyician achieved unlocking c EUROPEAN RESPIRATORY JOURNAL VOLUME 27 NUMBER

7 Eole3 XLS USER-FRIENDLINESS OF HOME VENTILATORS J. GONZALEZ-BERMEJO ET AL. Time Knighttar Nefti PV3 FIGURE 8. Timing reult for tet 6 (alarm). The graph how the time required to uccefully perform the tet for each of the ventilator teted. For each ventilator, the box correpond to the 75th percentile of the data ditribution with indication of the median, wherea the whiker indicate the 9th percentile. m: the reference time etablihed by the technician. time that were not tatitically different from the reference time, yet the difference (average 49 and 59, veru 12 for the technician) might be clinically ignificant in a crii ituation. The ISO :24 tandard [6] tate that mechanical control technique uch a lock, hielding, friction-loading and detent are conidered uitable. The preent author conider thee olution to be preferable to the current one, epecially when the preent olution impoe multiple button combination that are particularly anti-intuitive. Indeed, it i believed to be important to be able to unlock a ventilator relatively eaily, a thi i a prerequiite to any intervention if the need for a change in ventilatory mode or ventilatory etting arie. In a caricatural manner, if the concerned patient i ventilator-dependent or nearly o, failure to unlock the ventilator make a machine witch or manual ventilation the only olution. Recognition of etting Though the etting recognition chart were completed quite rapidly by the phyician, 49% of the chart were incorrect. The two main ource of error were, on the one hand, the equential diplay of the meaured value and the et value on the ame creen and, on the other hand, the heterogeneou terminology (table 2). Theoretically, correcting the firt factor would be imple; for manufacturer thi would involve allowing for the eparate diplay of meaured value and et value. Thi obviouly ha a cot, but i unlikely to be weighed againt the afety flaw revealed by the preent reult. Concerning heterogeneou terminology, it i probably up to the medical profeion to take action to etablih an international nomenclature for mode of aited ventilation. In France, CHOPIN and CHAMBRIN [8] have publihed a propoition of thi type in the journal Réanimation-Urgence. Recommendation have alo been iued by the French learned ociety for intenive care [9]. To the preent author knowledge, thee initiative have not had much following. Several Hélia2 not mutually excluive explanation can be put forward. Firt, the journal Réanimation-Urgence (now Réanimation ) i not indexed in the Medline databae. Secondly, the nomenclature propoed by CHOPIN and CHAMBRIN [8] i very phyiological in nature, but a certain degree of pragmatim i probably required, particularly concerning term that are already accepted through ue. Thirdly, awarene of the rik created by the abence of common terminology for mode of aited ventilation (whether home ventilation or in intenive care) i neceary at a medical community level, including the learned ocietie. It i hoped that thi tudy will contribute toward thi. Mode change, etting and alarm The reult of thee three tet appear to be, in a way, le worrying than the preceding tet. However, it remain that ome ventilator poed problem for certain phyician, including ome regarding the particularly important iue of alarm. It hould be emphaied that many phyician had inadvertently changed ventilator etting while trying to analye the preet parameter; thi poibility had not been foreeen in the tudy deign but would have warranted pecific analyi. Concluion Home mechanical ventilator have benefited from coniderable advance in deign and technology. They are ophiticated machine whoe reliability and performance are validated by detailed technical evaluation [3 5]. It i regrettable that thi technical excellence i tarnihed by inadequate ergonomic; at the mot, thi i an unjutifiable ource of rik for patient and, at the leat, a caue of uboptimal ue by phyician and caregiver. To ome extent, thi iue alo pertain to ICU mechanical ventilator about which ome reearch ha already been performed regarding technological pecificitie [1] and uer interface [11]. The reult of the evaluation carried out here hould encourage corrective action by both the manufacturer and the medical community. Thee action require intitutional management, through learned ociety working group (for example, with a view to drawing up an international nomenclature) or tatutory meaure. It i indeed urpriing that enitive device, uch a ventilator, are not ubject to evaluation regulation imilar to thoe in force for medication. Thu it would not be outrageou to enviage ventilator manufacturer being obliged to conform to a few imple regulation (tandardied tarting and locking ytem, homogeneou nomenclature). In any event, improving home ventilator uer-friendline i important (and would be relatively eay); ventilator will become more numerou with the diverification of indication for thi treatment method and increae in the population concerned. ACKNOWLEDGEMENTS The author would like to thank F. Bolgert, C. Cracco, S. Demeret, N. Deye, F. Lellouche, M. Prella, H. Prodanovic, C. Raynaud, M. Raux, C. Strau and M. Wyocki for the time they devoted to performing the tet. They would alo like to thank W. Broard for hi technical aitance, C. Melot for hi advice on tatitical analyi, and M. Amouyal-Jone for aitance with the Englih manucript VOLUME 27 NUMBER 6 EUROPEAN RESPIRATORY JOURNAL

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