***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: We tested the hypothesis that active and passive airway humidification minimize hypothermia in infants , but that maintaining normothermia does not decrease the duration of postoperative recovery . A circle system was used to ventilate the lungs of anesthetized , intubated infants who were r and omly assigned to active airway humidification and warming with use of an MR450 Servo airway heater and humidifier set at 37 ° C ( n = 10 ) , passive airway humidification with use of the Humid-Vent Mini heat and moisture exchanger placed between the Y-piece of the circle and the endotracheal tube ( n = 10 ) , or no airway humidification and heating ( control , n = 10 ) . Anesthesia was induced with thiopental and maintained with isoflurane and nitrous oxide in oxygen .  The relative humidity of inspired respiratory gases was ∼35 % in the control group and ∼90 % in the group undergoing active airway humidification . Initial inspired humidity in the passive humidification group ( 45 % ) increased to ∼80 % after 1 h of anesthesia . Humidity differed significantly across groups at all times ( P ≤ 0.05 ) . Steady-state rectal temperatures ( 100 - -120 min after induction ) were 36.2 ± 0.7 ° C in patients given active humidification and heating , 35.7 ± 0.9 ° C in the passively humidified group , and 35.2 ± 0.4 ° C in the control group ( P ≤ 0.05 between each group ) . Recovery from general anesthesia was rapid in all patients and did not correlate with central temperature changes or type of humidification ( P = NS ) . We conclude that heat and moisture exchangers are less effective than active heating and humidification , but significantly better than no humidification BACKGROUND The purpose of this study was to compare the performance of heat and moisture exchanger filters with heated humidifying systems in the mechanical ventilator circuit on the incidence of ventilator-associated pneumonia ( VAP ) and bacterial colonization . METHOD Two hundred and forty-three consecutive patients who required mechanical ventilation for 48 hours or more in the adult intensive care unit were r and omized to either a heat and moisture exchanger ( HME ) or a heated humidifying breathing circuit . RESULTS The VAP rate among the group with HME was 11.4 % ; the rate among the group with heated humidifying system ( HHS ) was 15.8 % . The difference was not statistically significant . Approximately 68 % of the patients in the HME group had no pathogen isolated compared with 50 % of the patients in the HHS group . This difference was statistically significant ( P = .006 ) . However , the distribution of the pathogens among those patients who had the isolated pathogens was mostly identical in the 2 groups . CONCLUSION Even though the study did not find HME to be significantly advantageous over the HHS , in as much as VAP rate is concerned , other advantages such as reduced nurses workload , reduced financial cost , and better safety made HME a more favorable device for use in our adult intensive care unit Background Minimizing total respiratory heat loss is an important goal during mechanical ventilation . The aim of the present study was to evaluate whether changes in tracheal temperature ( a clinical parameter that is easy to measure ) are reliable indices of total respiratory heat loss in mechanically ventilated patients . Method Total respiratory heat loss was measured , with three different methods of inspired gas conditioning , in 10 se date d patients . The study was r and omized and of a crossover design . Each patient was ventilated for three consecutive 24-h periods with a heated humidifier ( HH ) , a hydrophobic heat-moisture exchanger ( HME ) and a hygroscopic HME .  Total respiratory heat loss and tracheal temperature were simultaneously obtained in each patient . Measurements were obtained during each 24-h study period after 45 min , and 6 and 24 h. Results Total respiratory heat loss varied from 51 to 52 cal/min with the HH , from 100 to 108 cal/min with the hydrophobic HME , and from 92 to 102 cal/min with the hygroscopic HME ( P < 0.01 ) . Simultaneous measurements of maximal tracheal temperatures revealed no significant differences between the HH ( 35.7 - 35.9 ° C ) and either HME ( hydrophobic 35.3 - 35.4 ° C , hygroscopic 36.2 - 36.3 ° C ) . Conclusion In intensive care unit ( ICU ) mechanically ventilated patients , total respiratory heat loss was twice as much with either hydrophobic or hydroscopic HME than with the HH . This suggests that a much greater amount of heat was extracted from the respiratory tract by the HMEs than by the HH . Tracheal temperature , although simple to measure in ICU patients , does not appear to be a reliable estimate of total respiratory heat loss OBJECTIVE To compare the degree of bacterial circuit colonization , frequency of ventilator-associated pneumonia ( VAP ) , character of respiratory secretions , rewarming of hypothermic patients , disposable costs , and air flow resistance in intensive care patients ventilated using either a heat and moisture exchanger ( HME ) or hot water ( HW ) humidifier circuit .  DESIGN A prospect i ve , r and omized blinded trial of patients in the intensive care unit undergoing mechanical ventilation .  SETTING A metropolitan teaching hospital . PATIENTS One hundred sixteen patients undergoing mechanical ventilation for a minimum period of 48 hrs were enrolled . INTERVENTIONS Patients were r and omized to three ventilation groups using a ) an HW circuit with a 2-day circuit change ( n = 41 ) ; or b ) a bacterial-viral filtering HME in the circuit , with either a 2-day ( n = 42 ) ; or c ) a 4-day circuit change ( n = 33 ) . MEASUREMENTS AND MAIN RESULTS Circuit colonization was assessed using quantitative culture of washings taken from the circuit tubing and semiquantitative culture of swabs from the Y connectors . Sixty-seven percent of HW circuits became contaminated compared with 12 % in the two HME groups ( p < .0001 ) . Median colony counts were lower in the HME groups ( p < .0001 ) . If circuits at first circuit change were contaminated in the HW group , 89 % of subsequent circuit changes became contaminated compared with 0 % and 25 % for the 2- and 4-day HME groups , respectively . The frequency of VAP , the time to resolution of admission hypothermia , and the volume and fluidity of secretions were similar for all groups . The resistance of the HME after 24 hrs of use was < 0.025 cm H2O/L at gas flows of 40 L/min . HME use result ed in a cost reduction of $ 1.48 (Australian)/day . CONCLUSIONS Circuits with a bacterial-viral filtering HME are less readily colonized by bacteria . Contamination is a r and om event . Humidification technique has no influence on the frequency rate of VAP , the effectiveness of rewarming , nor the character of the respiratory secretions . Breathing resistance is generally low and disposable costs are reduced when an HME is used Abstract Objective In mechanically ventilated patients with induced hypothermia , the efficacy of heat and moisture exchangers and heated humidifiers to adequately humidify the airway is poorly known . The aim of the study was to assess the efficacy of different humidification devices during moderate hypothermia . Design Prospect i ve , cross-over r and omized study . Setting sMedical Intensive Care Unit in a University Hospital . Patients and participants Nine adult patients hospitalized after cardiac arrest in whom moderate hypothermia was induced ( 33 ° C for 24 h ) . Interventions Patients were ventilated at admission ( period design ated “ normothermia ” ) with a heat and moisture exchanger , and were r and omly ventilated during hypothermia with a heat and moisture exchanger , a heated humidifier , and an active heat and moisture exchanger . Measurements and results Core temperature , inspired and expired gas absolute and relative humidity were measured . Each system demonstrated limitations in its ability to humidify gases in the specific situation of hypothermia . Performances of heat and moisture exchangers were closely correlated to core temperature ( r2 = 0.84 ) . During hypothermia , heat and moisture exchangers led to major under-humidification , with absolute humidity below 25 mgH2O/l . The active heat and moisture exchanger slightly improved humidification . Heated humidifiers were mostly adequate but led to over-humidification in some patients , with inspiratory absolute humidity higher than maximal water content at 33 ° C with a positive balance between inspiratory and expiratory water content . Conclusions These results suggest that in the case of moderate hypothermia , heat and moisture exchangers should be used cautiously and that heated humidifiers may lead to over-humidification with the currently recommended setting Heat and moisture exchangers ( HME ) are increasingly used to warm and humidify inspired gases in intubated ventilated patients . But these devices add dead space that may alter the alveolar ventilation . This could impair the efficiency of spontaneous ventilation ( SV ) during weaning trials from mechanical ventilation . Fifteen patients were tested with an HME ( Hygrobac-DAR ) and a heated humidifier ( HH ) ( Fischer-Paykel MR 450 ) in a r and om order during weaning trials in SV with inspiratory pressure support . Minute ventilation VE , tidal volume ) , and respiratory rate were recorded and arterial blood was sample d for blood gas analysis with each device . The HME gave a significantly greater VE than the HH ( 9.3 + /- 0.8 L/min vs 8.1 + /- 0.8 L/min ; p < 0.005 ) , because of increased respiratory rate ( 21 + /- 2/min vs 19 + /- 2/min ; p < 0.05 ) . Tidal volume was unchanged for HME and HH ( 470 + /- 32 mL vs 458 + /- 39 mL ) . The higher PaCO2 with HME than with HH ( 44 + /- 2 mm Hg vs 42 + /- 2 mm Hg ; p < 0.005 ) revealed an insufficient alveolar ventilation response to the increase in dead space . Arterial Po2 rose with the HME , but not significantly above the HH values ( 103 + /- 6 mm Hg vs 97 + /- 6 mm Hg ; p = 0.055 ) , possibly because of a positive end-expiratory pressure effect of the HME . The need to increase VE in SV when an HME is used should be taken into account during difficult weaning from mechanical ventilation Objective : To investigate the mechanical effects of artificial noses . Setting : A general intensive care unit of a university hospital . Patients : 10 patients in pressure support ventilation for acute Introduction Some guidelines to prevent  ventilator-associated pneumonia ( VAP ) do not establish a recommendation for the preferential use of either heat and moisture exchangers ( HMEs ) or heated humidifiers ( HHs ) , while other guidelines clearly advocate the use of HMEs . The aim of this study was to determine the incidence of VAP associated with HHs or HMEs . Methods A r and omized study was conducted in the intensive care unit of a university hospital involving patients expected to require mechanical ventilation for > 5 days . Patients were assigned to two groups ; one group received HH and the other group received HME . Tracheal aspirate sample s were obtained on endotracheal intubation , then twice a week , and finally on extubation , in order to diagnose VAP . Throat swabs were taken on admission to the intensive care unit , then twice a week , and finally at discharge from the intensive care unit in order to classify VAP as primary endogenous , secondary endogenous , or exogenous . Results A total of 120 patients were assigned to HMEs ( 60 patients ) and HHs ( 60 patients ) ; 16 patients received mechanical ventilation for less than five days and were excluded from the analysis . Data analysis of the remaining 104 patients ( 53 HMEs and 51 HHs ) showed no significant differences between groups regarding sex , age , Acute Physiology and Chronic Health Evaluation II score , pre-VAP use of antibiotics , days on mechanical ventilation , and diagnosis group . VAP was found in eight of 51 ( 15.69 % ) patients in the HH group and in 21 of 53 ( 39.62 % ) patients in the HME group ( P = 0.006 ) . The median time free of VAP was 20 days ( 95 % confidence interval , 13.34–26.66 ) for the HH group and was 42 days ( 95 % confidence interval , 35.62–48.37 ) for the HME group ( P < 0.001 ) . Cox regression analysis showed the HME as a risk factor for VAP ( hazard rate , 16.2 ; 95 % confidence interval , 4.54–58.04 ; P < 0.001 ) . Conclusion The patients mechanically ventilated for more than five days developed a lower incidence of VAP with a HH than with a HME Purpose To compare the effects of two humidifier systems on endotracheal tube ( ETT ) resistance during mechanical ventilation , either an active heated humidifier ( HH ) or a passive heat and moisture exchanger ( HME ) was selected using current clinical recommendations . Methods This 
    Output:
    
Conclusions In this meta- analysis we found no superiority of HMEs and HHs , in terms of artificial airway occlusion , pneumonia and mortality .