Early versus Late Tracheostomy Promotes Weaning in Intensive Care Unit Patients

Background and aim of the study: The time interval between the patients’ intubation and the performance of a tracheostomy has been considered as critical for the disease prognosis and outcome. The aim of the present study was to compare and contrast the outcomes of early vs late tracheostomy with regard to intensive care unit (ICU) patients’ weaning from respiratory support. Methods: This retrospective observational study, involved patients who were hospitalized in two general and one Covid-19 ICUs of two tertiary hospitals in Athens and were subjected to tracheostomy. Data were collected from the patients’ medical records in order to estimate the duration of patient weaning and the number of days from the patients’ intubation until the time of tracheostomy. In the present study the term early tracheostomy denotes tracheostomy performed within 14 days from patient intubation and late tracheostomy defines the tracheostomy carried out after 14 days. For Covid-19 patients, guidelines suggested that tracheostomies should be performed 21 days following intubation, due to the high risk of virus transmission. Results: One hundred and thirty-one patients who underwent tracheostomy participated in the study. Most tracheostomies were performed using the percutaneous technique. The group of patients tracheostomized within 14 days after their admission in ICU weaned faster from respiratory support compared to ones who were tracheostomized after 14 days. Conclusions: The most common distinction between early and late tracheostomy is 14 days, with early tracheostomy being more beneficial in terms of patients’ outcomes, and specifically ICU patients’ weaning. (www.actabiomedica.it)

Cooling Strategies for Greenhouses in Summer: Control of Fogging by Pulse Width Modulation

The possibilities for improving the control of greenhouse fogging systems, were studied by comparing several combinations of ventilation cooling techniques, shade screening and low-pressure fogging. The study was divided into three parts: experiments, modelling and simulations. In the first part of the paper, ten combinations of five cooling techniques were tested during the summers of 2002 and 2003 in a 132m2 greenhouse with a steel structure and a single-layer methacrylate cover located in Madrid, Spain. An analysis of variance of the climatic parameters was carried out to determine which combinations produced significant differences in inside temperature or relative humidity. Comparing the values for the inside to outside temperature difference, the combination of a shade screen and above-screen fogging achieved a difference in temperature almost the same as that for under-screen fogging, but the relative humidity was significantly lower. In the second part of the study a dynamic model was developed (2002) and validated (2003). The mean absolute error obtained for inside temperature was similar in the fit and the validation and it was less than 1.5 1C in both cases. The model was used to simulate the inside air temperature for a fog system working without shading, and above and under a shade screen. Control algorithms were developed for reducing system water consumption. In the three cases a simple on/off control with a fixed fogging cycle was compared with a pulse width modulation (PWM) strategy, in which the duration of the fogging pulse was increased as a function of inside temperature. The strategies with PWM applied to the fog system were able to reduce water consumption by 8–15% with respect to the strategies with a fixed fogging cycle

Cumulative Prognostic Score Predicting Mortality in Patients Older Than 80 Years Admitted to the ICU.

OBJECTIVES: To develop a scoring system model that predicts mortality within 30 days of admission of patients older than 80 years admitted to intensive care units (ICUs). DESIGN: Prospective cohort study. SETTING: A total of 306 ICUs from 24 European countries. PARTICIPANTS: Older adults admitted to European ICUs (N = 3730; median age = 84 years [interquartile range = 81-87 y]; 51.8% male). MEASUREMENTS: Overall, 24 variables available during ICU admission were included as potential predictive variables. Multivariable logistic regression was used to identify independent predictors of 30-day mortality. Model sensitivity, specificity, and accuracy were evaluated with receiver operating characteristic curves. RESULTS: The 30-day-mortality was 1562 (41.9%). In multivariable analysis, these variables were selected as independent predictors of mortality: age, sex, ICU admission diagnosis, Clinical Frailty Scale, Sequential Organ Failure Score, invasive mechanical ventilation, and renal replacement therapy. The discrimination, accuracy, and calibration of the model were good: the area under the curve for a score of 10 or higher was .80, and the Brier score was .18. At a cut point of 10 or higher (75% of all patients), the model predicts 30-day mortality in 91.1% of all patients who die. CONCLUSION: A predictive model of cumulative events predicts 30-day mortality in patients older than 80 years admitted to ICUs. Future studies should include other potential predictor variables including functional status, presence of advance care plans, and assessment of each patient's decision-making capacity

Sepsis at ICU admission does not decrease 30-day survival in very old patients: a post-hoc analysis of the VIP1 multinational cohort study.

BACKGROUND: The number of intensive care patients aged ≥ 80 years (Very old Intensive Care Patients; VIPs) is growing. VIPs have high mortality and morbidity and the benefits of ICU admission are frequently questioned. Sepsis incidence has risen in recent years and identification of outcomes is of considerable public importance. We aimed to determine whether VIPs admitted for sepsis had different outcomes than those admitted for other acute reasons and identify potential prognostic factors for 30-day survival. RESULTS: This prospective study included VIPs with Sequential Organ Failure Assessment (SOFA) scores ≥ 2 acutely admitted to 307 ICUs in 21 European countries. Of 3869 acutely admitted VIPs, 493 (12.7%) [53.8% male, median age 83 (81-86) years] were admitted for sepsis. Sepsis was defined according to clinical criteria; suspected or demonstrated focus of infection and SOFA score ≥ 2 points. Compared to VIPs admitted for other acute reasons, VIPs admitted for sepsis were younger, had a higher SOFA score (9 vs. 7, p < 0.0001), required more vasoactive drugs [82.2% vs. 55.1%, p < 0.0001] and renal replacement therapies [17.4% vs. 9.9%; p < 0.0001], and had more life-sustaining treatment limitations [37.3% vs. 32.1%; p = 0.02]. Frailty was similar in both groups. Unadjusted 30-day survival was not significantly different between the two groups. After adjustment for age, gender, frailty, and SOFA score, sepsis had no impact on 30-day survival [HR 0.99 (95% CI 0.86-1.15), p = 0.917]. Inverse-probability weight (IPW)-adjusted survival curves for the first 30 days after ICU admission were similar for acute septic and non-septic patients [HR: 1.00 (95% CI 0.87-1.17), p = 0.95]. A matched-pair analysis in which patients with sepsis were matched with two control patients of the same gender with the same age, SOFA score, and level of frailty was also performed. A Cox proportional hazard regression model stratified on the matched pairs showed that 30-day survival was similar in both groups [57.2% (95% CI 52.7-60.7) vs. 57.1% (95% CI 53.7-60.1), p = 0.85]. CONCLUSIONS: After adjusting for organ dysfunction, sepsis at admission was not independently associated with decreased 30-day survival in this multinational study of 3869 VIPs. Age, frailty, and SOFA score were independently associated with survival

Relationship between the Clinical Frailty Scale and short-term mortality in patients ≥ 80 years old acutely admitted to the ICU: a prospective cohort study.

BACKGROUND: The Clinical Frailty Scale (CFS) is frequently used to measure frailty in critically ill adults. There is wide variation in the approach to analysing the relationship between the CFS score and mortality after admission to the ICU. This study aimed to evaluate the influence of modelling approach on the association between the CFS score and short-term mortality and quantify the prognostic value of frailty in this context. METHODS: We analysed data from two multicentre prospective cohort studies which enrolled intensive care unit patients ≥ 80 years old in 26 countries. The primary outcome was mortality within 30-days from admission to the ICU. Logistic regression models for both ICU and 30-day mortality included the CFS score as either a categorical, continuous or dichotomous variable and were adjusted for patient's age, sex, reason for admission to the ICU, and admission Sequential Organ Failure Assessment score. RESULTS: The median age in the sample of 7487 consecutive patients was 84 years (IQR 81-87). The highest fraction of new prognostic information from frailty in the context of 30-day mortality was observed when the CFS score was treated as either a categorical variable using all original levels of frailty or a nonlinear continuous variable and was equal to 9% using these modelling approaches (p < 0.001). The relationship between the CFS score and mortality was nonlinear (p < 0.01). CONCLUSION: Knowledge about a patient's frailty status adds a substantial amount of new prognostic information at the moment of admission to the ICU. Arbitrary simplification of the CFS score into fewer groups than originally intended leads to a loss of information and should be avoided. Trial registration NCT03134807 (VIP1), NCT03370692 (VIP2)

Influence of misting on the diurnal hysteresis of canopy transpiration rate and conductance in a rose greenhouse

The aim of this study was to evaluate the effects of greenhouse air humidity control on the transpiration rate (TR) and canopy stomatal conductance (gc) of a soilless rose crop (Rosa hybrida, cv. First Red) grown on perlite bags. Measurements of TR, canopy net radiation (Rn), air (Ta) and canopy (Tc) temperature, and air vapour pressure deficit (VPDa) were made in a glasshouse located in the coastal area of eastern Greece during several summer days. The greenhouse was operated (i) without air humidity control and (ii) with control by means of a fog-system operating when the relative humidity of the glasshouse air was lower than 75%. The diurnal course of gc was determined from the relation linking TR to canopy-to-air vapour pressure deficit (VPDC) or from inversion of the Penman-Monteith equation. The two ways of estimating gc were in agreement. Diurnal hysteresis of TR and gc in relation to VPD C were observed and showed different patterns according to changes in the daily amplitudes of VPDC induced by the humidity control system. The hysteresis phenomena were less strong when the fog-system was operating. The changes in the daily course of TR and gc were probably due to the stomatal response to vapour pressure deficit. Thus the prediction of short-term variations of TR and gc in greenhouse environments must account for the magnitude and time-course of VPDC

Influence of aluminized thermal screens on greenhouse microclimate and night transpiration

The aim of this work was to characterize the influence of a thermal screen on: the greenhouse microclimate, energy savings and crop transpiration. Measurements were carried out during winter in a glasshouse cultivated with a rose crop and equipped with an aluminized thermal screen. Air temperature and humidity were recorded at 0.3 m, 0.8 m and 1.8 m high inside the greenhouse. Net radiation over and under the thermal screen; and under the rose crop, leaf temperature and crop transpiration were simultaneously monitored. The results indicated that the thermal screen induced a more homogeneous microclimate, and increased air temperature and canopy temperature by about 2.5°C and 3°C respectively. Canopy net radiation was increased while transpiration was similar in both cases, showing cyclic fluctuations that appeared to be due to internal physiological control processes rather than to response to microclimatic variables. The air vapour pressure deficit VPD in the lower part of the canopy was similar in both cases, as well as the canopy to air VPD and the dew-point temperature. These results suggest that the use of a thermal screen brings several advantages, such as a more homogeneous greenhouse microclimate, a reduction in heat consumption and a significant increase in canopy temperature in the lower part of the crop, but does not improve the humidity conditions

Effect of misting on transpiration and conductances of a greenhouse rose canopy

The influence of greenhouse humidity control on the transpiration rate (lambdaE(c)). sensible heat flux (H-c) and bulk stomatal conductance (g(c)) of a soilless rose canopy (Rosa hybrida. cv. First Red) was studied in a greenhouse located in the coastal area of eastern Greece. Measurements were carried out during several days in the summer (i) without air humidity control and (ii) with a mist system operating when the relative humidity of the greenhouse air was lower than 75%. The diurnal course of g(c) was determined from the relation linking lambdaE(c) to canopy-to-air vapour pressure deficit (D-c) or from inversion of the Penman-Monteith equation. The two ways of estimating g(c) were in good agreement, showing a significant increase of g(c) under mist conditions. Covariation of radiation and humidity during the day caused diurnal hysteresis in lambdaE(c) and g(c). The hysteresis phenomena were less marked when the mist system was operating. Normalising g(c) by radiation removed most of the hysteresis and indicated a curvilinear stomatal response to vapour pressure deficit. The analysis of the energy partition at the canopy showed high negative values of the Bowen ratio (beta approximate to -0.7) in both conditions, indicating that canopy transpiration played a major role in cooling the greenhouse atmosphere. The contribution of the mist system to total evaporative cooling was estimated to be about 20%, with only 40-50% of the mist water being effectively used in cooling. Calculation of the crop water stress index confirmed that the crop was less stressed under misting conditions. It was concluded that the prediction of short-term variations of lambdaE(c) and g(c) in greenhouse environments must account for the magnitude and diurnal variation of air VPD. (C) 2001 Elsevier Science B.V. All rights reserved

Transpiration and energy balance of a greenhouse rose crop in mediterranean summer conditions

The transpiration rate of a soilless rose crop and its interactions with the greenhouse microclimate and energy balance were investigated during summer conditions in Greece. At this aim, measurements of transpiration (γE c), canopy net radiation (Rn), air and canopy temperature (Ti and Tc, respectively), and air vapour pressure deficit (VPDi) were carried out during June and July 1998 in a white-washed glasshouse equipped with fan assistant ventilation. The sensible heat flux of the canopy (Hc) was deduced from the data of γEc and Rn. The results indicated that, although high air VPD were prevailing in the greenhouse (until 5 kPa), the transpiration rate was maintained rather high throughout the day at a level equivalent to double the net radiation. Canopy temperature was found significantly lower than air temperature during most of the day. The canopy conductance to water vapour transfer (gc) was estimated from the direct relationship linking transpiration to canopy-to-air VPD. The maximum values of gc were observed in the early morning, near 10 a.m. Afterwards, gc decreased and, during the afternoon, was found rather constant. Calculation of the crop water stress index (CWSI) indicated that, despite the high VPD, radiation and air temperature, the crop was only slightly stressed, the CWSI being not higher than 0.30 during this period. It was concluded that the crop was able to maintain a high physiological activity throughout the day. The ability of the crop to respond to the high evaporative demand created by the environmental conditions may be ascribed to the high crop LAI (about 4), roof whitening and adequate water supply, probably associated to a well-developed root system

Use of model-artificial leaves for monitoring aerodynamic conductance in greenhouses

Improving the design, control and management of greenhouse ventilation systems requires a better comprehension of the coupling and feedback mechanisms between the crop, the internal climate and the outside climate. The objective of this work was to characterize the leaf boundary-layer conductance (g b) under greenhouse conditions and to study its dependence on ventilation rate and outside conditions. For this purpose, continuous estimation of gb was carried out in a greenhouse cultivated with rose plants, using rose leaf replicas consisting of a pair of model artificial leaves, one being heated and the other unheated. The boundary layer conductance was derived from the energy balance of the pair of model leaves. Inside air velocity measurements were made by means of a 3-D sonic anemometer. The analysis of the data indicated that, for a given vent aperture and wind direction, there is a clear link between gb and the outside wind speed, and therefore between gb and the ventilation conductance. This relation can be described by a simple linear function in the conditions of our experiments. Using this function for expressing the global greenhouse conductance as a function of the leaf area index allowed getting a better insight on the coupling between the crop and the outside climate. The results also confirm that this model sensor (artificial leaves) might have potential applications in the evaluation of the ventilation performances, as well as in greenhouse climate control and management