Hospitalized mechanically ventilated patients are at higher risk of enteral underfeeding than non-ventilated patients

BACKGROUND & AIMS

Enteral nutrition (EN) is the preferred method of nutrition support in hospitalized patients but only 50-90% of the required calories are actually delivered. In order to identify where our nutrition support team (NST) should focus its activity, we prospectively evaluated the level of coverage of energy and protein needs during the first 5 days of EN in intensive care unit (ICU) and non-ICU patients and the relationship of energy and protein coverage with serum albumin, transthryretin, insulin-like growth factor-1 (IGF-1) and C-reactive protein (CRP).

METHODS

Subjects (n=183) who required nutrition support and received EN were prospectively recruited. Calorie prescription was 20 and 25, 25 and 30 kcal/kg BW for women and men 60 years and <60 years, respectively. Protein needs were estimated as 1.2g protein/kg BW. Logistic regression analysis was used to estimate odds ratios (OR) for energy and protein delivery 66.6% and <66.6% and albumin, transthryretin, IGF-1 (low vs. normal) and CRP (high vs. normal) in ventilated vs. non-ventilated patients.

RESULTS

Significantly more mechanically ventilated than non-ventilated patients received <66.6% of energy (71% vs. 48%) and protein (96% vs. 65%). The ventilated patients were more likely to be energy (OR 2.1, CI 1.1-4.0) and protein (OR 15.7, CI 4.9-50.8) underfed than non-ventilated patients. There was a significant association on day 5 between low protein delivery and low albumin (OR 2.9, CI 1.3-6.5), low transthyretin (OR 3.0, CI 1.4-6.5), low IGF-1 (OR 2.8, CI 1.2-6.7) and high CRP (OR 3.5, CI 1.6-7.8).

CONCLUSIONS

The energy and protein needs of hospitalized patients are not met during the first 5 days of EN. Ventilated patients are more likely to be energy and protein underfed than non-ventilated patients and to have low plasma protein level. These findings support our decision to intensify EN monitoring by our NST in ventilated patients to optimize their nutritional coverage.

A multicenter randomized trial of computer-driven protocolized weaning from mechanical ventilation

RATIONALE AND OBJECTIVES

Duration of weaning from mechanical ventilation may be reduced by the use of a systematic approach. We assessed whether a closed-loop knowledge-based algorithm introduced in a ventilator to act as a computer-driven weaning protocol can improve patient outcomes as compared with usual care.

METHODS AND MEASUREMENTS

We conducted a multicenter randomized controlled study with concealed allocation to compare usual care for weaning with computer-driven weaning. The computerized protocol included an automatic gradual reduction in pressure support, automatic performance of spontaneous breathing trials (SBT), and generation of an incentive message when an SBT was successfully passed. One hundred forty-four patients were enrolled before weaning initiation. They were randomly allocated to computer-driven weaning or to physician-controlled weaning according to local guidelines. Weaning duration until successful extubation and total duration of ventilation were the primary endpoints.

MAIN RESULTS

Weaning duration was reduced in the computer-driven group from a median of 5 to 3 d (p=0.01) and total duration of mechanical ventilation from 12 to 7.5 d (p=0.003). Reintubation rate did not differ (23 vs. 16%, p=0.40). Computer-driven weaning also decreased median intensive care unit (ICU) stay duration from 15.5 to 12 d (p=0.02) and caused no adverse events. The amount of sedation did not differ between groups. In the usual care group, compliance to recommended modes and to SBT was estimated, respectively, at 96 and 51%.

CONCLUSIONS

The specific computer-driven system used in this study can reduce mechanical ventilation duration and ICU length of stay, as compared with a physician-controlled weaning process.

Automatic adjustment of pressure support by a computer-driven knowledge-based system during noninvasive ventilation: a feasibility study

OBJECTIVE

To evaluate the feasibility of using a knowledge-based system designed to automatically titrate pressure support (PS) to maintain the patient in a "respiratory comfort zone" during noninvasive ventilation (NIV) in patients with acute respiratory failure.

DESIGN AND SETTING

Prospective crossover interventional study in an intensive care unit of a university hospital.

PATIENTS

Twenty patients.

INTERVENTIONS

After initial NIV setting and startup in conventional PS by the chest physiotherapist NIV was continued for 45 min with the automated PS activated.

MEASUREMENTS AND RESULTS

During automated PS minute-volume was maintained constant while respiratory rate decreased significantly from its pre-NIV value (20+/-3 vs. 25+/-3 bpm). There was a trend towards a progressive lowering of dyspnea. In hypercapnic patients PaCO(2) decreased significantly from 61+/-9 to 51+/-2 mmHg, and pH increased significantly from 7.31+/-0.05 to 7.35+/-0.03. Automated PS was well tolerated. Two system malfunctions occurred prompting physiotherapist intervention.

CONCLUSIONS

The results of this feasibility study suggest that the system can be used during NIV in patients with acute respiratory failure. Further studies should now determine whether it can improve patient-ventilator interaction and reduce caregiver workload.

ESPEN Guidelines on Enteral Nutrition: Intensive care

Enteral nutrition (EN) via tube feeding is, today, the preferred way of feeding the critically ill patient and an important means of counteracting for the catabolic state induced by severe diseases. These guidelines are intended to give evidence-based recommendations for the use of EN in patients who have a complicated course during their ICU stay, focusing particularly on those who develop a severe inflammatory response, i.e. patients who have failure of at least one organ during their ICU stay. These guidelines were developed by an interdisciplinary expert group in accordance with officially accepted standards and are based on all relevant publications since 1985. They were discussed and accepted in a consensus conference. EN should be given to all ICU patients who are not expected to be taking a full oral diet within three days. It should have begun during the first 24h using a standard high-protein formula. During the acute and initial phases of critical illness an exogenous energy supply in excess of 20-25 kcal/kg BW/day should be avoided, whereas, during recovery, the aim should be to provide values of 25-30 total kcal/kg BW/day. Supplementary parenteral nutrition remains a reserve tool and should be given only to those patients who do not reach their target nutrient intake on EN alone. There is no general indication for immune-modulating formulae in patients with severe illness or sepsis and an APACHE II Score >15. Glutamine should be supplemented in patients suffering from burns or trauma.

Low initial trough plasma concentrations of lopinavir are associated with an impairment of virological response in an unselected cohort of HIV-1-infected patients

OBJECTIVES

The relationship between lopinavir trough plasma concentration at baseline and virological efficacy 3 months after the beginning of the therapy was investigated in an unselected cohort of HIV-1-infected patients

METHODS

According to initial trough lopinavir plasma level, patients were classified into three groups: the subtherapeutic group (<3 mg/L, n=18), the therapeutic group (between 3 and 8 mg/L, n=50) and the toxic group (>8 mg/L, n=16). The virological response after 3 months of lopinavir treatment, defined as a viral load <200 HIV-1 RNA copies/mL, was compared amongst these groups.

RESULTS

The virological response was significantly different (P<0.05) between the subtherapeutic group (22.% of patients with viral load<200 copies/mL) and the other groups (56.0% of patients with a viral load<200 copies/mL in the therapeutic group and 56.2% in the toxic group).

CONCLUSIONS

A lower virological efficacy should be expected for experienced or naive patients with plasma trough lopinavir concentrations<3 mg/L at the beginning of treatment.

A simple high performance liquid chromatography assay for monitoring plasma concentrations of tipranavir in HIV infected patients

A simple HPLC assay to determine plasma concentration of tipranavir is presented. A liquid/liquid extraction of the drugs in ethyl acetate/hexane from 250 microL of plasma is followed by a reversed phase isocratic HPLC assay with UV detection at 205 nm. The imprecision and inaccuracy are lower than 10%, the low limit of quantitation is 0.4 mg/L. Thus, this method can be used for therapeutic drug monitoring of tipranavir in HIV infected patients.

How a novel programme for increasing awareness of health professionals resulted in a 14% decrease in patients using excessive doses of psychotropic drugs in western France

INTRODUCTION

Consumption of high doses of psychotropic drugs is a public health problem in France. The Center for Evaluation and Information on Pharmacodependence and the General Health Insurance System decided that it was time to begin a regional programme on excessive consumption in a French region.

PURPOSE

The objectives of this programme were: (1) get health professionals (doctors and pharmacists) to realize that some of their patients were consuming excessive doses, and (2) achieve a decrease of excessive psychotropic drug use. In addition, in the course of the programme, we were able to gather some clinical data related to heavy consumers, and evaluate their possible addiction.

METHOD

This study is based on data related to 497,821 psychotropic drug consumers. Psychotropic drugs consumers whose consumption had exceeded twice the maximum allowance during at least 3 months in the second half of 2002 were contacted and unless the patients objected, a report on their personal circumstances was sent to their doctor(s) and pharmacist(s). We determined a quantitative method for the assessment of the results.

RESULTS

Increasing awareness among the health professionals through this original programme resulted in a 14.1% decrease in the percentage of patients receiving excessive doses, a 66% decrease in the number of patients receiving more than twice the maximum recommended dose, among the selected cohort, and some rationalization of consumption as well as a decrease in the "doctor shopping" behaviour.

CONCLUSIONS

Medical practices did evolve and health professionals became aware of the benefit of their preventive action on the decrease of drug addiction.

Non-invasive ventilation in the recovery room for postoperative respiratory failure: a feasibility study

BACKGROUND

Non-invasive ventilation (NIV) has become a standard of care in acute respiratory failure. However, little data is available on its usefulness in recovery ward patients after general surgery. The present study aimed to document the feasibility of implementing NIV in this setting, and its impact on lung function.

METHODS

During a 12-month period, all adult patients who underwent elective general surgical procedures under general anaesthesia during weekdays, were transferred to the recovery ward after extubation, and those who required NIV were included in this prospective observational study. NIV was applied with a bilevel device (VPAP II ST, ResMed, North Ryde, Australia).

RESULTS

4622 patients were admitted to the recovery ward, 83 of whom needed NIV. NIV increased pH (7.38 +/- .06 vs 7.30 +/- .05), reduced PaCO2 (7.38 +/- .06 vs 7.30 +/- .05) in hypercapnic patients (44 +/- 9 vs 55 +/- 10 mm Hg), and increased PaO2 in non-hypercapnic patients (80 +/- 10 vs 70 +/- 11 mm Hg). No complications attributable to NIV occurred. Most patients improved after 1-2 NIV trials, and all were transferred to the ward the same day.

CONCLUSIONS

In recovery ward patients after general surgery, NIV is seldom required. When applied, NIV seems to exert favourable effects on lung function. NIV can be safely implemented with a bilevel device in a recovery ward not accustomed to the use of ICU ventilators. The cost-effectiveness of its systematic use in this setting should be assessed.

Impact of Expiratory Trigger Setting on Delayed Cycling and Inspiratory Muscle Workload

RATIONALE

During pressure-support ventilation, the ventilator cycles into expiration when inspiratory flow decreases to a given percentage of peak inspiratory flow ("expiratory trigger"). In obstructive disease, the slower rise and decrease of inspiratory flow entails delayed cycling, an increase in intrinsic positive end-expiratory pressure, and nontriggering breaths.

OBJECTIVES

We hypothesized that setting expiratory trigger at a higher than usual percentage of peak inspiratory flow would attenuate the adverse effects of delayed cycling.

METHODS

Ten intubated patients with obstructive disease undergoing pressure support were studied at expiratory trigger settings of 10, 25, 50, and 70% of peak inspiratory flow.

MEASUREMENTS

Continuous recording of diaphragmatic EMG activity with surface electrodes, and esophageal and gastric pressures with a dual-balloon nasogastric tube.

MAIN RESULTS

Compared with expiratory trigger 10, expiratory trigger 70 reduced the magnitude of delayed cycling (0.25 +/- 0.18 vs. 1.26 +/- 0.72 s, p < 0.05), intrinsic positive end-expiratory pressure (4.8 +/- 1.9 vs. 6.5 +/- 2.2 cm H(2)O, p < 0.05), nontriggering breaths (2 +/- 3 vs. 9 +/- 5 breaths/min, p < 0.05), and triggering pressure-time product (0.9 +/- 0.8 vs. 2.1 +/- 0.7 cm H2O . s, p < 0.05).

CONCLUSIONS

Setting expiratory trigger at a higher percentage of peak inspiratory flow in patients with obstructive disease during pressure support improves patient-ventilator synchrony and reduces inspiratory muscle effort. Further studies should explore whether these effects can influence patient outcome.

Clinical evaluation of hormonal stress state in medical ICU patients: a prospective blinded observational study

OBJECTIVE

To evaluate whether classification of patients as having low, moderate, or high stress based on clinical parameters is associated with plasma levels of stress hormone.

DESIGN AND SETTING

Prospective, blinded, observational study in an 18-bed medical ICU.

PATIENTS

Eighty-eight consecutive patients.

INTERVENTIONS

Patients were classified as low (n=28), moderate (n=33) or high stress (n=27) on days 0 and 3 of ICU stay, based on 1 point for each abnormal parameter: body temperature, heart rate, systemic arterial pressure, respiratory rate, physical agitation, presence of infection and catecholamine administration. The stress categories were: high: 4 points or more, moderate 2-3 points, low 1 point. Plasma growth hormone (GH), insulin-like growth factor 1 (IGF-1), insulin, glucagon, cortisol were measured on days 0 and 3.

MEASUREMENTS AND RESULTS

Plasma cortisol and glucagon were significantly higher and IGF-1 lower in high vs. low stress patients on days 0 and 3. High stress patients were more likely to have high cortisol levels (odds ratio 5.8, confidence interval 1.8-18.9), high glucagon (8.7, 2.1-36.1), and low IGF-1 levels (5.9, 1.8-19.0) than low stress patients on day 0. Moderate stress patients were also more likely to have high cortisol and glucagon levels than low stress patients. Insulin and GH did not differ significantly. Results were similar for day 3.

CONCLUSIONS

Moderate and severe stress was significantly associated with high catabolic (cortisol, glucagon) and low anabolic (IGF-1) hormone levels. The hormonal stress level in ICU patients can be estimated from simple clinical parameters during routine clinical evaluation.

Helium-oxygen decreases inspiratory effort and work of breathing during pressure support in intubated patients with chronic obstructive pulmonary disease

OBJECTIVE

To evaluate the impact of helium-oxygen (He/O2) on inspiratory effort and work of breathing (WOB) in intubated COPD patients ventilated with pressure support.

DESIGN AND SETTING

Prospective crossover interventional study in the medical ICU of a university hospital.

PATIENTS AND PARTICIPANTS

Ten patients.

INTERVENTIONS

Sequential inhalation (30 min each) of three gas mixtures: (a) air/O2, (b) He/O2 (c) air/O2, at constant FIO2 and level of pressure support.

MEASUREMENTS AND RESULTS

Inspiratory effort and WOB were determined by esophageal and gastric pressure. Throughout the study pressure support and FIO2 were 14+/-3 cmH2O and 0.33+/-0.07 respectively. Compared to Air/O2, He/O2 reduced the number of ineffective breaths (4+/-5 vs. 9+/-5 breaths/min), intrinsic PEEP (3.1+/-2 vs. 4.8+/-2 cmH2O), the magnitude of negative esophageal pressure swings (6.7+/-2 vs. 9.1+/-4.9 cmH2O), pressure-time product (42+/-37 vs. 67+/-65 cmH2O s(-1) min(-1)), and total WOB (11+/-3 vs. 18+/-10 J/min). Elastic (6+/-1 vs. 10+/-6 J/min) and resistive (5+/-1 vs. 9+/-4 J/min) components of the WOB were decreased by He/O2.

CONCLUSIONS

In intubated COPD patients ventilated with pressure support He/O2 reduces intrinsic PEEP, the number of ineffective breaths, and the magnitude of inspiratory effort and WOB. He/O2 could prove useful in patients with high levels of PEEPi and WOB ventilated in pressure support, for example, during weaning.

[Non invasive ventilation in emergency settings]

The use of non invasive ventilation (NIV) in the emergency setting to treat acute respiratory failure (ARF) has received much attention. To date, large studies support the early administration of continuous positive airway pressure (CPAP) in patients with cardiogenic acute pulmonary edema; and 2) non-invasive positive pressure ventilation (NPPV) for exacerbations of chronic obstructive pulmonary disease (COPD). NIV could also be useful in other types of ARF, but its success rate is dependent on the cause of ARF and patient's characteristics. Use of NIV in the emergency setting should take into account validated indications and local expertise of the nursing staff to minimize the risk of complications.

Inhaled nitric oxide therapy in adults: European expert recommendations

BACKGROUND

Inhaled nitric oxide (iNO) has been used for treatment of acute respiratory failure and pulmonary hypertension since 1991 in adult patients in the perioperative setting and in critical care.

METHODS

This contribution assesses evidence for the use of iNO in this population as presented to a expert group jointly organised by the European Society of Intensive Care Medicine and the European Association of Cardiothoracic Anaesthesiologists.

CONCLUSIONS

Expert recommendations on the use of iNO in adults were agreed on following presentation of the evidence at the expert meeting held in June 2004.

Non-invasive ventilation in the recovery room for postoperative respiratory failure: a feasibility study

BACKGROUND

Non-invasive ventilation (NIV) has become a standard of care in acute respiratory failure. However, little data is available on its usefulness in recovery ward patients after general surgery. The present study aimed to document the feasibility of implementing NIV in this setting, and its impact on lung function.

METHODS

During a 12-month period, all adult patients who underwent elective general surgical procedures under general anaesthesia during weekdays, were transferred to the recovery ward after extubation, and those who required NIV were included in this prospective observational study. NIV was applied with a bilevel device (VPAP II ST, ResMed, North Ryde, Australia).

RESULTS

4622 patients were admitted to the recovery ward, 83 of whom needed NIV. NIV increased pH (7.38 +/- .06 vs 7.30 +/- .05), reduced PaCO2 (7.38 +/- .06 vs 7.30 +/- .05) in hypercapnic patients (44 +/- 9 vs 55 +/- 10 mm Hg), and increased PaO2 in non-hypercapnic patients (80 +/- 10 vs 70 +/- 11 mm Hg). No complications attributable to NIV occurred. Most patients improved after 1-2 NIV trials, and all were transferred to the ward the same day.

CONCLUSIONS

In recovery ward patients after general surgery, NIV is seldom required. When applied, NIV seems to exert favourable effects on lung function. NIV can be safely implemented with a bilevel device in a recovery ward not accustomed to the use of ICU ventilators. The cost-effectiveness of its systematic use in this setting should be assessed.

Performance Characteristics of 10 Home Mechanical Ventilators in Pressure-Support Mode

OBJECTIVE

Inspiratory pressure (Pi) support delivered by a bilevel device has become the technique of choice for noninvasive home ventilation. Considerable progress has been made in the performance and functionality of these devices. The present bench study was designed to compare the various characteristics of 10 recently developed bilevel Pi devices under different conditions of respiratory mechanics.

DESIGN

Bench model study.

SETTING

Research laboratory, university hospital.

MEASUREMENTS

Ventilators were connected to a lung model, the mechanics of which were set to normal, restrictive, and obstructive, that was driven by an ICU ventilator to mimic patient effort. Pressure support levels of 10 and 15 cm H(2)O, and maximum were tested, with "patient" inspiratory efforts of 5, 10, 15, 20, and 25 cm H(2)O. Tests were conducted in the absence and presence of leaks in the system. Trigger delay, trigger-associated inspiratory workload, pressurization capabilities, and cycling were analyzed.

RESULTS

All devices had very short trigger delays and triggering workload. Pressurization capability varied widely among the machines, with some bilevel devices lagging behind when faced with a high inspiratory demand. Cycling was usually not synchronous with patient inspiratory time when the default settings were used, but was considerably improved by modifying cycling settings, when that option was available.

CONCLUSIONS

A better knowledge of the technical performance of bilevel devices (ie, pressurization capabilities and cycling profile) may prove to be useful in choosing the machine that is best suited for a patient's respiratory mechanics and inspiratory demand. Clinical algorithms to help set cycling criteria for improving patient-ventilator synchrony and patient comfort should now be developed.

Determination of atazanavir and other antiretroviral drugs (indinavir, amprenavir, nelfinavir and its active metabolite M8, saquinavir, ritonavir, lopinavir, nevirapine and efavirenz) plasma levels by high performance liquid chromatography with UV detection

A global method is proposed for therapeutic drug monitoring of atazanavir, a novel protease inhibitor and of all other protease inhibitors (PI) and non nucleoside reverse transcriptase inhibitors (NNRTI) which are currently used to treat HIV patients. All drugs are extracted after a liquid-liquid extraction and separated on a C18 column with a binary gradient elution except lopinavir which is separated without this gradient. The absorbance is measured at 259 nm except for lopinavir (205 nm) and nevirapine (320 nm). This method is specific, accurate, precise (the intra-day and inter-day imprecision and inaccuracy are lower than 15%) and the limits of quantitation (0.40 mg/L for nevirapine, 0.10 mg/L for indinavir, 0.10 mg/l for M8, 0.05 mg/L for amprenavir, 0.10 mg/L for nelfinavir, 0.10 mg/L for saquinavir, 0.10 mg/L for ritonavir, 0.10 mg/L for efavirenz, 0.10 mg/L for atazanavir and 0.20 mg/L for lopinavir) are consistent with trough plasma concentrations allowing to use this method for therapeutic drug monitoring of PI and NNRTI.

Pharmacology of new antipsychotic drugs: are they stabilizers of schizophrenic psychosis?

Antipsychotic drugs with greater efficacy and tolerance have been sought and studied in recent years. Some of them could be used in new treatment strategies to replace the D(2) receptor antagonism induced by classic neuroleptics such as haloperidol. The development strategies in this field are not only focused on discovering specific antagonists of one subtype of dopaminergic receptor, but on the synthesis of molecules having different effects on different brain areas. Drugs with limbic and frontal cortex specificity are associated with improved tolerance, increased efficacy against negative symptoms and a higher quality of life for patients. Furthermore, some investigation is being made into the possibility of alternatives to the dopaminergic system as a target for antipsychotics. Serotonergic antagonists and alpha-adrenoceptor antagonists, for example, are also being considered as potential options in the treatment of mental diseases such as schizophrenia.

Expiratory trigger setting in pressure support ventilation: from mathematical model to bedside

OBJECTIVE

To evaluate the feasibility of relying on a mathematical model to adjust the optimal level of expiratory trigger, materialized by the ratio of inspiratory flow at the end of inspiratory effort (V'ti) and peak inspiratory flow (V'peak), or V'ti/V'peak, during pressure support, by comparing its predicted values with those measured in intubated patients.

DESIGN

Prospective observational study.

SETTING

Medical intensive care unit, university hospital.

PATIENTS

There were 28 intubated patients undergoing pressure support.

INTERVENTIONS

Pressure support as set by the clinician in charge.

MEASUREMENTS AND MAIN RESULTS

A significant correlation was found between predicted and measured V'ti/V'peak ratios (r =.70; p <.001; mean +/- sd difference, -0.025 +/- 0.07; 95% confidence interval, -0.161 to 0.111). Overall, delayed cycling occurred in obstructive conditions, the delay increasing as obstructive disease was more severe.

CONCLUSIONS

A significant correlation was observed between predicted values of V'ti/V'peak and those values measured in patients undergoing pressure support. These findings should stimulate further research into the possible applications of this mathematical model to optimize expiratory trigger setting. Furthermore, our findings suggest that expiratory trigger should be adjustable and provide a wider range of cutoff levels than that which is currently available.

Higher calorie prescription improves nutrient delivery during the first 5 days of enteral nutrition

AIMS

It is unclear whether prescribing a higher amount of calories by enteral nutrition (EN) increases actual delivery. This prospective controlled study aimed at comparing the progression of EN of two study populations with different levels of calorie prescriptions, during the first 5 days of EN.

METHODS

The daily calorie prescription of group 1 (n=346) was 25 and 20 kcal/kg body weight for women <60 and > or =60 years, respectively, and 30 and 25 kcal/kg body weight for men <60 and > or =60 years, respectively. The prescription of group 2 (n=148) was 5 kcal/kg body weight higher than in group 1. Calorie intakes were expressed as percentage of resting energy expenditure (REE) and protein intakes as percentage of requirements estimated as 1.2 g/kg body weight/day. Patients were classified as <60 and > or =60 years and as medical or surgical patients. Statistical analysis was performed with ANOVA for repeated measures.

RESULTS

Calorie and protein deliveries increased in both groups independently of age and ward categories (P< or =0.0001). Group 2 showed faster progressions of calorie and protein intakes than group 1 in patients altogether (P< or =0.002), > or =60 years (P< or =0.01) and in surgical patients (P< or =0.02). Differences of calorie and protein intakes between day 1 and day 5 were significantly higher in group 2 than group 1 for patients altogether (75+/-61 vs. 56+/-54% of REE; 41+/-30 vs. 31+/-/-27% of protein requirements), those over 60 years (76+/-67 of REE vs. 52+/-59 of protein requirements) and surgical patients (81+/-52 vs. 58+/-57% of REE; 44+/-27 vs. 33+/-29% of protein requirements).

CONCLUSIONS

Increasing the levels of EN prescriptions improved calorie and protein deliveries. While the mean energy delivery over 5 days was sufficient to cover requirements, the protein delivery by EN was insufficient, despite our nutritional support team.

Effects of acute treatment with paroxetine, citalopram and venlafaxine in vivo on noradrenaline and serotonin outflow: a microdialysis study in Swiss mice

1. This study investigated whether a single administration of a range of doses (1, 4 and 8 mg kg-1, i.p.) of paroxetine, citalopram or venlafaxine may simultaneously increase extracellular levels of 5-HT ([5-HT]ext) and noradrenaline ([NA]ext) by using in vivo microdialysis in the frontal cortex (FCx) of awake, freely moving Swiss mice. 2. In vivo, paroxetine induced similar increases in cortical [5-HT]ext at the three doses tested, and induced a statistically significant increase in cortical [NA]ext at 4 and 8 mg x kg-1. Citalopram increased neither [5-HT]ext nor [NA]ext at the lowest dose, but increased both neurotransmitter levels at 4 and 8 mg x kg-1. At these doses, citalopram induced greater increases in cortical [5-HT]ext than in [NA]ext. Venlafaxine increased [5-HT]ext and [NA]ext to about 400 and 140% of the respective basal values at 8 mg kg-1. 3. Citalopram and paroxetine have the highest potency to increase cortical [5-HT]ext and [NA]ext, respectively. In addition, the rank of order of efficacy of these antidepressant drugs to increase [5-HT]ext in vivo in the FCx of mice was as follows: venlafaxine>citalopram>paroxetine, while the efficacy to increase cortical [NA]ext in mice of paroxetine and citalopram is similar, and greater than that of venlafaxine. 4. In conclusion, extracellular levels of cortical [NA]ext increase with the highest doses of the very selective SSRI citalopram, as well as with the very potent SSRI paroxetine. Surprisingly, the SNRI venlafaxine increased cortical [5-HT]ext to a greater extent rather than [NA]ext in the range of doses studied in mice.

Effects of helium-oxygen on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in a porcine model of stable methacholine-induced bronchospasm

OBJECTIVE

To explore the consequences of helium/oxygen (He/O(2)) inhalation on respiratory mechanics, gas exchange, and ventilation-perfusion (VA/Q) relationships in an animal model of severe induced bronchospasm during mechanical ventilation.

DESIGN

Prospective, interventional study.

SETTING

Experimental animal laboratory, university hospital.

INTERVENTIONS

Seven piglets were anesthetized, paralyzed, and mechanically ventilated, with all ventilator settings remaining constant throughout the protocol. Acute stable bronchospasm was obtained through continuous aerosolization of methacholine. Once steady-state was achieved, the animals successively breathed air/O(2) and He/O(2) (FIO(2) 0.3), or inversely, in random order. Measurements were taken at baseline, during bronchospasm, and after 30 min of He/O(2) inhalation.

RESULTS

Bronchospasm increased lung peak inspiratory pressure (49+/-6.9 vs 18+/-1 cm H(2)O, P<0.001), lung resistance (22.7+/-1.5 vs 6.8+/-1.5 cm H(2)O x l(-1).s, P<0.001), dynamic elastance (76+/-11.2 vs 22.8+/-4.1 cm H(2)O x l(-1), P<0.001), and work of breathing (1.51+/-0.26 vs 0.47+/-0.08, P<0.001). Arterial pH decreased (7.47+/-0.06 vs 7.32+/-0.06, P<0.001), PaCO(2) increased, and PaO(2) decreased. Multiple inert gas elimination showed an absence of shunt, substantial increases in perfusion to low VA/Q regions, and dispersion of VA/Q distribution. He/O(2) reduced lung resistance and work of breathing, and worsened hypercapnia and respiratory acidosis.

CONCLUSIONS

In this model, while He/O(2) improved respiratory mechanics and reduced work of breathing, hypercapnia and respiratory acidosis increased. Close attention should be paid to monitoring arterial blood gases when He/O(2) is used in mechanically ventilated acute severe asthma.