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Christian Putensen

Publications and source records attributed to Christian Putensen.

At least 19 recordsLinked to original sources
PubMed2006

Dynamic versus static respiratory mechanics in acute lung injury and acute respiratory distress syndrome.

OBJECTIVES: It is not clear whether the mechanical properties of the respiratory system assessed under the dynamic condition of mechanical ventilation are equivalent to those assessed under static conditions. We hypothesized that the analyses of dynamic and static respiratory mechanics provide different information in acute respiratory failure. DESIGN: Prospective multiple-center study. SETTING: Intensive care units of eight German university hospitals. PATIENTS: A total of 28 patients with acute lung injury and acute respiratory distress syndrome. INTERVENTIONS: None. MEASUREMENTS: Dynamic respiratory mechanics were determined during ongoing mechanical ventilation with an incremental positive end-expiratory pressure (PEEP) protocol with PEEP steps of 2 cm H2O every ten breaths. Static respiratory mechanics were determined using a low-flow inflation. MAIN RESULTS: The dynamic compliance was lower than the static compliance. The difference between dynamic and static compliance was dependent on alveolar pressure. At an alveolar pressure of 25 cm H2O, dynamic compliance was 29.8 (17.1) mL/cm H2O and static compliance was 59.6 (39.8) mL/cm H2O (median [interquartile range], p < .05). End-inspiratory volumes during the incremental PEEP trial coincided with the static pressure-volume curve, whereas end-expiratory volumes significantly exceeded the static pressure-volume curve. The differences could be attributed to PEEP-related recruitment, accounting for 40.8% (10.3%) of the total volume gain of 1964 (1449) mL during the incremental PEEP trial. Recruited volume per PEEP step increased from 6.4 (46) mL at zero end-expiratory pressure to 145 (91) mL at a PEEP of 20 cm H2O (p < .001). Dynamic compliance decreased at low alveolar pressure while recruitment simultaneously increased. Static mechanics did not allow this differentiation. The decrease in static compliance occurred at higher alveolar pressures compared with the dynamic analysis. CONCLUSIONS: Exploiting dynamic respiratory mechanics during incremental PEEP, both compliance and recruitment can be assessed simultaneously. Based on these findings, application of dynamic respiratory mechanics as a diagnostic tool in ventilated patients should be more appropriate than using static pressure-volume curves.

Acute Disease↗
PubMed2006

The impact of spontaneous breathing during mechanical ventilation.

PURPOSE OF REVIEW: In patients with acute respiratory distress syndrome, controlled mechanical ventilation is generally used in the initial phase to ensure adequate alveolar ventilation, arterial oxygenation, and to reduce work of breathing without causing further damage to the lungs. Although introduced as weaning techniques, partial ventilator support modes have become standard techniques for primary mechanical ventilator support. This review evaluates the physiological and clinical effects of persisting spontaneous breathing during ventilator support in patients with acute respiratory distress syndrome. RECENT FINDINGS: The improvements in pulmonary gas exchange, systemic blood flow and oxygen supply to the tissue which have been observed when spontaneous breathing has been maintained during mechanical ventilation are reflected in the clinical improvement in the patient's condition. Computer tomography observations demonstrated that spontaneous breathing improves gas exchange by redistribution of ventilation and end-expiratory gas to dependent, juxtadiaphragmatic lung regions and thereby promotes alveolar recruitment. Thus, spontaneous breathing during ventilator support counters the undesirable cyclic alveolar collapse in dependent lung regions. In addition, spontaneous breathing during ventilator support may prevent increase in sedation beyond a level of comfort to adapt the patient to mechanical ventilation which decreases duration of mechanical ventilator support, length of stay in the intensive care unit, and overall costs of care giving. SUMMARY: In view of the recently available data, it can be concluded that maintained spontaneous breathing during mechanical ventilation should not be suppressed even in patients with severe pulmonary functional disorders.

Analgesia↗
PubMed2006

The effects of mechanical ventilation on the gut and abdomen.

PURPOSE OF REVIEW: Mechanical ventilation generates an increase in airway pressure and, therefore, in intrathoracic pressure, which may decrease systemic and intraabdominal organ perfusion. Critically ill patients rarely die of hypoxia and/or hypercarbia but commonly develop a systemic inflammatory response that culminates in multiple-organ dysfunction syndrome and death. In the pathogeneses of this syndrome the gastrointestinal tract and liver have received considerable attention. RECENT FINDINGS: Mechanical ventilation with high positive end-expiratory pressure has been found to decrease splanchnic perfusion. Hepatic arterial buffer response is preserved and an increased hepatic arterial blood flow will compensate the decrease in portal blood flow. Despite an increased cardiac output with an acute moderate increase in arterial PCO2 during protective ventilation it cannot be expected that splanchnic and gut perfusion is improved. In the absence of a significant rise in intraabdominal pressure without impairment in cardiovascular function, splanchnic and gastrointestinal function remained unchanged during short periods of prone positioning. Spontaneous breathing during ventilator support improves systemic blood flow and gastrointestinal and splanchnic perfusion. SUMMARY: In critically ill patients mechanical ventilation should be adjusted to avoid conditions known to be associated with decreased gastrointestinal and splanchnic perfusion.

Abdomen↗
PubMed2005

Spontaneous breathing with airway pressure release ventilation favors ventilation in dependent lung regions and counters cyclic alveolar collapse in oleic-acid-induced lung injury: a randomized controlled computed tomography trial.

INTRODUCTION: Experimental and clinical studies have shown a reduction in intrapulmonary shunt with spontaneous breathing during airway pressure release ventilation (APRV) in acute lung injury. This reduction was related to reduced atelectasis and increased aeration. We hypothesized that spontaneous breathing will result in better ventilation and aeration of dependent lung areas and in less cyclic collapse during the tidal breath. METHODS: In this randomized controlled experimental trial, 22 pigs with oleic-acid-induced lung injury were randomly assigned to receive APRV with or without spontaneous breathing at comparable airway pressures. Four hours after randomization, dynamic computed tomography scans of the lung were obtained in an apical slice and in a juxtadiaphragmatic transverse slice. Analyses of regional attenuation were performed separately in nondependent and dependent halves of the lungs on end-expiratory scans and end-inspiratory scans. Tidal changes were assessed as differences between inspiration and expiration of the mechanical breaths. RESULTS: Whereas no differences were observed in the apical slices, spontaneous breathing resulted in improved tidal ventilation of dependent lung regions (P < 0.05) and less cyclic collapse (P < 0.05) in the juxtadiaphragmatic slices. In addition, with spontaneous breathing, the end-expiratory aeration increased and nonaerated tissue decreased in dependent lung regions close to the diaphragm (P < 0.05 for the interaction ventilator mode and lung region). CONCLUSION: Spontaneous breathing during APRV redistributes ventilation and aeration to dependent, usually well-perfused, lung regions close to the diaphragm, and may thereby contribute to improved arterial oxygenation. Spontaneous breathing also counters cyclic collapse, which is a risk factor for ventilation-associated lung injury.

Animals↗
PubMed2005

Mechanical ventilation strategies and inflammatory responses to cardiac surgery: a prospective randomized clinical trial.

OBJECTIVE: To examine whether postoperative mechanical ventilation with lower tidal volumes (V(T)) has protective effects on inflammatory responses induced by cardiopulmonary bypass (CPB) surgery in smokers and nonsmokers. DESIGN AND SETTING: Prospective, randomized, controlled clinical trial in the intensive care unit of a university hospital. PATIENTS AND PARTICIPANTS: We examined 44 patients (22 smokers, 22 nonsmokers) immediately after uncomplicated CPB surgery. INTERVENTIONS: Ventilation was applied for 6 h with either V(T) of either 6 or 12 ml/kg ideal body weight. MEASUREMENTS AND RESULTS: The time course of serum tumor necrosis factor (TNF) alpha, interleukin (IL) 6, and IL-8 determined 0, 2, 4, and 6 h after randomization did not differ significantly between the ventilatory strategies. By contrast, in bronchoalveolar lavage fluids sampled after 6 h only TNF-alpha levels were significantly higher in the high V(T) group than the low V(T) group (50+/-111 pg/ml vs. 1+/-7 pg/ml). IL-6 and IL-8 concentrations did not differ between groups. Subgroup analysis of patients with serum TNF-alpha level higher than 0 pg/ml after surgery revealed lower TNF-alpha serum levels during lower V(T) ventilation. All observed effects were small, independent of patients' history of smoking, and were not correlated with duration of ventilation and ICU stay. CONCLUSIONS: Ventilation with lower V(T) had no or only minor effect on systemic and pulmonary inflammatory responses in patients with healthy lungs after uncomplicated CPB surgery. Our data do not suggest a clinical benefit of using low V(T) ventilation in these selected patients.

Aged↗
PubMed2005

Prognostic value of plasma N-terminal pro-brain natriuretic peptide in patients with severe sepsis.

BACKGROUND: Increased plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) have been identified as predictors of cardiac dysfunction and prognosis in congestive heart failure and ischemic heart disease. In severe sepsis patients, however, no information is available yet about the prognostic value of natriuretic peptides. Therefore, the aim of the present study was to determine the role of the N-terminal prohormone forms of ANP (NT-proANP) and BNP (NT-proBNP) in the context of outcome of septic patients. Furthermore, the effect of treatment with recombinant human activated protein C [drotrecogin alfa (activated)] on plasma levels of natriuretic peptides in severe sepsis was evaluated. METHODS AND RESULTS: Fifty-seven patients with severe sepsis were included. Levels of NT-proANP and NT-proBNP were measured on the second day of sepsis by ELISA. Septic patients with NT-proBNP levels >1400 pmol/L were 3.9 times more likely (relative risk [RR], 3.9; 95% CI, 1.6 to 9.7) to die from sepsis than patients with lower NT-proBNP values (P<0.01). NT-proANP levels, however, were not predictive of survival in our patient population. A highly significant correlation was found between troponin I levels and plasma concentrations of NT-proBNP in septic patients (r=0.68, P<0.0001). In addition, troponin I significantly accounted for the variation in NT-proBNP levels (P<0.0001), suggesting an important role for NT-proBNP in the context of cardiac injury and dysfunction in septic patients. Twenty-three septic patients who received treatment with drotrecogin alfa (activated) presented with significantly lower concentrations of NT-proANP, NT-proBNP, and troponin I compared with patients not receiving drotrecogin alfa (activated). CONCLUSIONS: NT-proBNP may serve as useful laboratory marker to predict survival in patients presenting with severe sepsis.

APACHE↗
PubMed2005

Prone position in mechanically ventilated patients -- the hard or the soft way?

Prone positioning may even in patients without abdominal hypertension result in an increased intra-abdominal pressure (IAP). Previous research could not demonstrate a marked increase in IAP associated with cardiovascular, renal, or hepato-splanchnic dysfunction when patients were proned in air-cushioned beds. Michelet and colleagues in this issue of Critical Care report that the increase in IAP in the prone position depends on the used mattress type. Compared with air-cushion beds, conventional foam mattresses resulted in a greater increase in IAP which was associated with a decrease in the plasma disappearance rate of indocyanin green (PDRICG) indicating inadequate heptosplanchnic function.

Animals↗
PubMed2005

Assisted breathing is better in acute respiratory failure.

PURPOSE OF REVIEW: Mechanical ventilation is usually provided in acute lung injury to ensure alveolar ventilation and reduce the patients' work of breathing without further damaging the lungs by the treatment itself. Although partial ventilatory support modalities were initially developed for weaning from mechanical ventilation, they are increasingly used as primary modes of ventilation, even in patients in the acute phase of pulmonary dysfunction. The aim of this paper is to review the role of spontaneous breathing ventilatory modalities with respect to their physiologic or clinical evidence. RECENT FINDINGS: By allowing patients with acute lung injury to breathe spontaneously, one can expect improvement in gas exchange and in systemic blood flow, on the basis of both experimental and clinical trials. In addition, by increasing end-expiratory lung volume, as will occur when airway pressure release ventilation is used, recruitment of collapsed or consolidated lung is likely to occur, especially in juxtadiaphragmatic lung regions. Until recently, traditional approaches to mechanical ventilatory support of patients with acute lung injury have called for adaptation of the patient to the mechanical ventilator using heavy sedation and administration of neuromuscular blocking agents. Recent investigations have questioned the utility of sedation, muscle paralysis, and mechanical control of ventilation. Further, evidence exists that lowering sedation levels will decrease the duration of mechanical ventilatory support, the length of stay in the intensive care unit, and the overall costs of hospitalization. SUMMARY: On the basis of currently available data, the authors suggest the use of techniques of mechanical ventilatory support that maintain, rather than suppress, spontaneous ventilatory effort, especially in patients with severe pulmonary dysfunction.

Analgesia↗
PubMed2005

Spontaneous breathing affects the spatial ventilation and perfusion distribution during mechanical ventilatory support.

OBJECTIVE: In acute respiratory failure, gas exchange improves with spontaneous breathing during airway pressure release ventilation (APRV). The mechanisms for this improvement are not fully clear. We have shown that APRV with spontaneous breathing reopens nonaerated lung tissue in dorsal juxtadiaphragmatic regions. We hypothesized that spontaneous breathing during APRV may redistribute ventilation and perfusion toward these reopened regions. DESIGN: Prospective, randomized, controlled study. SETTING: Animal research laboratory SUBJECTS: Twenty controlled mechanically ventilated pigs. INTERVENTIONS: Lung injury was induced by injection of oleic acid into the central circulation; thereafter, pigs were randomized to APRV with or without spontaneous breathing. To induce spontaneous breathing during APRV with spontaneous breathing, the mechanical respiratory rate was decreased by 50% in this group. MEASUREMENTS AND MAIN RESULTS: We measured respiratory mechanics, hemodynamics, gas exchange including the multiple inert gas elimination technique, and the spatial ventilation and perfusion distribution using single photon emission tomography. At similar minute ventilation and airway pressures, shunt remained stable during APRV with spontaneous breathing, whereas it increased during APRV without spontaneous breathing during the 2-hr study period (p = .006). Single photon emission tomography showed more ventilation (p < .001) and pulmonary blood (p < .025) flow in dorsal, juxtadiaphragmatic lung regions when spontaneous breathing was present. CONCLUSIONS: The beneficial effects of spontaneous breathing on intrapulmonary shunt and oxygenation are explained both by increased ventilation of aerated dependent lung tissue and by opening up nonaerated tissue so that ventilation is distributed to a larger share of the lung. Redistribution of perfusion is possibly secondary to the altered ventilation. The overall effect is a more efficient use of available lung tissue for gas exchange.

Animals↗
PubMed2005

Proportional assist versus pressure support ventilation in patients with acute respiratory failure: cardiorespiratory responses to artificially increased ventilatory demand.

OBJECTIVE: To test the hypothesis that in response to increased ventilatory demand, dynamic inspiratory pressure assistance better compensates for increased workload compared with static pressure support ventilation (PSV). DESIGN: Randomized clinical crossover study. SETTING: General intensive care u nits of a university hospital. PATIENTS: Twelve patients with acute respiratory failure. INTERVENTIONS: Patients received PSV, proportional assist ventilation (PAV), and PAV+ automatic tube compensation (ATC) in random order while maintaining mean inspiratory airway pressure constant. During each setting, ventilatory demand was increased by adding deadspace without ventilator readjustment. MEASUREMENTS AND MAIN RESULTS: Cardiorespiratory, ventilatory, and work of breathing variables were assessed by routine monitoring plus pneumotachography; airway, esophageal, and abdominal pressure measurements; and nitrogen washout. After deadspace addition, tidal volume and end-expiratory lung volume increased similarly in all ventilatory modalities. Ventilator work, peak inspiratory flow, and maximum airway pressure increased significantly during PAV+ATC when compared with PSV after deadspace addition. However, increase in ventilator work did not result in a smaller increase in patients' work of breathing with elevated ventilatory demand during PAV+ATC (PSV 807 +/- 204 mJ/L, PAV 802 +/- 193 mJ/L, and PAV+ATC 715 +/- 202 mJ/L, p = .11). Increase in patients' work of breathing was mainly caused by a significantly higher resistive workload during PAV and PAV+ATC. CONCLUSION: In patients with acute respiratory failure, dynamic inspiratory pressure assistance modalities are not superior to PSV with respect to cardiorespiratory function and inspiratory muscles unloading after increasing ventilatory demand. The latter might be explained by higher peak flows resulting in nonlinearly increased resistive workload that was incompletely compensated by PAV+ATC.

Acute Disease↗
PubMed2005

Drotrecogin alfa (activated) treatment in severe sepsis from the global open-label trial ENHANCE: further evidence for survival and safety and implications for early treatment.

OBJECTIVE: To provide further evidence for the efficacy and safety of drotrecogin alfa (activated) treatment in severe sepsis. DESIGN: Single-arm, open-label, trial of drotrecogin alfa (activated) treatment in severe sepsis patients. Enrollment began in March 2001 and day-28 follow-up completed in January 2003. SETTING: ENHANCE took place in 25 countries at 361 sites. PATIENTS: Patients with known or suspected infection, three or four systemic inflammatory response syndrome criteria, and one or more sepsis-induced organ dysfunctions. Of 2,434 adults entered, 2,378 received drotrecogin alfa (activated), and of these, 2,375 completed the protocol. INTERVENTIONS: Drotrecogin alfa (activated) was infused at a dose of 24 mug/kg/hr for 96 hrs. MEASUREMENTS AND MAIN RESULTS: The 28-day all-cause mortality approximated that observed in PROWESS (25.3% vs. 24.7%). Although patients in ENHANCE had increased serious bleeding rates compared with patients in the drotrecogin alfa (activated) arm of PROWESS (during infusion, 3.6% vs. 2.4%; postinfusion, 3.2% vs. 1.2%; 28-day, 6.5% vs. 3.5%), increased postinfusion bleeding suggested a higher background bleeding rate. Intracranial hemorrhage was more common in ENHANCE than PROWESS (during infusion, 0.6% vs. 0.2%; 28-day, 1.5% vs. 0.2%). The incidence of fatal intracranial hemorrhage was the same during infusion (0.2%) and higher at 28 days (0.5% vs. 0.2%). ENHANCE patients treated within 0-24 hrs from their first sepsis-induced organ dysfunction had lower observed mortality rate than those treated after 24 hrs (22.9% vs. 27.4%, p = .01). CONCLUSIONS: ENHANCE provides supportive evidence for the favorable benefit/risk ratio observed in PROWESS and suggests that more effective use of drotrecogin alfa (activated) might be obtained by initiating therapy earlier.

Adult↗
PubMed2005

Methodologic aspects of attenuation distributions from static and dynamic thoracic CT techniques in experimental acute lung injury.

BACKGROUND: In acute lung injury, thoracic CT is used to gain information about lung aeration and consolidation. This can be done either during breath-holding by spiral CT scanning of the entire lung or dynamically by scanning lung slices without interrupting ventilation. We hypothesized that attenuation distribution is dependent on static or dynamic scanning techniques. We also studied whether a variation in the CT cut level, corresponding to the diaphragm movement over a breath, had any effect on the attenuation distribution. METHODS: Twenty-two pigs with oleic acid-induced lung injury were randomly assigned to receive pressure-controlled mechanical ventilation with or without spontaneous breathing. Transversal dynamic CT scans of the chest were performed in apical and juxtadiaphragmatic regions, and end-expiratory and end-inspiratory slices were selected. In addition, after clamping the tube at end-expiration and end-inspiration, respectively, spiral CTs were performed. Guided by morphologic structures, spiral CT slices matching the dynamic scan slice and three additional neighbored slices above the diaphragm were selected. Distributions of CT attenuation were calculated and summarized in ranges for comparison. RESULTS: No significant difference in attenuation distributions between the two scanning methods or an interaction with the factors ventilation mode, ventilation phase, and attenuation range were found. In addition, attenuation distributions of four neighbored juxtadiaphragmatic slices, 8 mm thick, from the spiral CT did not differ statistically. CONCLUSION: In an animal model of oleic acid-induced lung injury, analyses of transverse thoracic slices based on dynamic or static CT scanning showed comparable distributions of attenuation. Variations on the CT cut level of 24 mm had no significant effect on the distribution of Hounsfield unit numbers. CT attenuation distributions of transversal juxtadiaphragmatic slices were not dependent on exact position.

Animals↗
PubMed2005

Effects of spontaneous breathing during airway pressure release ventilation on respiratory work and muscle blood flow in experimental lung injury.

STUDY OBJECTIVES: To evaluate the effects of spontaneous breathing at ambient airway pressure (Paw) and during airway pressure release ventilation (APRV) on respiratory work and respiratory muscle blood flow (RMBF) in experimental lung injury. DESIGN: Prospective experimental study. SETTING: Research laboratory of a university hospital. SUBJECTS: Twelve hemodynamically stable, analgosedated, and tracheotomized domestic pigs. MEASUREMENTS: Respiratory work was estimated by the inspiratory pressure time product (PTPinsp) of esophageal pressure, and RMBF was measured with colored microspheres. Lung injury was induced with IV boli of oleic acid. The first set of measurements was performed before induction of lung injury while pigs were breathing spontaneously at ambient Paw, the second after induction of lung injury while breathing spontaneously at ambient Paw, and the third with lung injury and spontaneous breathing with APRV. RESULTS: After induction of lung injury PTPinsp increased from 138 +/- 14 to 214 +/- 32 cm H2O s/min when pigs breathed spontaneously at ambient Paw (p < 0.05) and returned to 128 +/- 27 cm H2O s/min during APRV. While systemic hemodynamics and blood flow to the psoatic and intercostal muscles did not change, diaphragmatic blood flow increased from 0.34 +/- 0.05 before to 0.54 +/- 0.08 mL/g/min after induction of lung injury and spontaneous breathing at ambient Paw (p < 0.05) and returned to 0.32 +/- 0.05 mL/g/min during APRV (p < 0.05 vs spontaneous breathing at ambient Paw [lung injury]). CONCLUSION: Respiratory work and RMBF are increased in acute lung injury when subjects breathe spontaneously at ambient Paw. Supporting spontaneous breathing with APRV decreases respiratory work and RMBF to physiologic values.

Animals↗
PubMed2004

Clinical review: biphasic positive airway pressure and airway pressure release ventilation.

This review focuses on mechanical ventilation strategies that allow unsupported spontaneous breathing activity in any phase of the ventilatory cycle. By allowing patients with the acute respiratory distress syndrome to breathe spontaneously, one can expect improvements in gas exchange and systemic blood flow, based on findings from both experimental and clinical trials. In addition, by increasing end-expiratory lung volume, as occurs when using biphasic positive airway pressure or airway pressure release ventilation, recruitment of collapsed or consolidated lung is likely to occur, especially in juxtadiaphragmatic lung legions. Traditional approaches to mechanical ventilatory support of patients with acute respiratory distress syndrome require adaptation of the patient to the mechanical ventilator using heavy sedation and even muscle relaxation. Recent investigations have questioned the utility of sedation, muscle paralysis and mechanical control of ventilation. Furthermore, evidence exists that lowering sedation levels will decrease the duration of mechanical ventilatory support, length of stay in the intensive care unit, and overall costs of hospitalization. Based on currently available data, we suggest considering the use of techniques of mechanical ventilatory support that maintain, rather than suppress, spontaneous ventilatory effort, especially in patients with severe pulmonary dysfunction.

Analgesia↗
PubMed2004

The effects of different ventilatory settings on pulmonary and systemic inflammatory responses during major surgery.

UNLABELLED: Mechanical ventilation with high tidal volumes (V(T)) and zero or low positive end-expiratory pressure increased mediator release to inflammatory stimuli or acute lung injury. We studied whether mechanical ventilation modifies the inflammatory responses during major thoracic or abdominal surgery. Sixty-four patients undergoing elective thoracotomy (n = 34) or laparotomy (n = 30) were randomized to receive either mechanical ventilation with V(T) = 12 or 15 mL/kg ideal body weight, respectively, and zero end-expiratory pressure, or V(T) = 6 mL/kg ideal body weight with positive end-expiratory pressure of 10 cm H(2)O. In 62 patients who completed the study, arterial oxygenation was not different between groups. Tumor necrosis factor, interleukin (IL)-1, IL-6, IL-8, IL-10, and IL-12 were determined by cytometric bead array in plasma after 0, 1, 2, and 3 h and in tracheal aspirates after 3 h of mechanical ventilation. Data were log-transformed and analyzed using parametric or nonparametric tests, as indicated. All plasma mediators increased more during abdominal than during thoracic surgery, although the differences were small. However, neither time course nor concentrations of pulmonary or systemic mediators differed between the two ventilatory settings. Our data suggest that the ventilatory settings we studied do not affect inflammatory reactions during major surgery within 3 h. IMPLICATIONS: In 62 patients undergoing elective major thoracic or abdominal surgery, mechanical ventilation with low tidal volumes and positive end-expiratory pressure or high tidal volumes and zero end-expiratory pressure did not result in different pulmonary or systemic levels of measured inflammatory markers.

Abdomen↗
PubMed2003

Remifentanil for analgesia-based sedation in the intensive care unit.

Providing effective analgesia and adequate sedation is a generally accepted goal of intensive care medicine. Due to its rapid, organ independent and predictable metabolism the short acting opioid remifentanil might be particularly useful for analgesia-based sedation in the intensive care unit (ICU). This hypothesis was tested by two studies in this issue of Critical Care. The study by Breen et al. shows that remifentanil does not exert prolonged clinical effects when continuously infused in renal failure patients, although the weak acting metabolite remifentanil acid accumulates. The study by Muellejans et al. reports a multicenter trial comparing a remifentanil versus a fentanyl based regimen in ICU patients. With both substances a target analgesia and sedation level was reached, and no major differences were found when frequent assessments of the sedation level and according readjustments of doses were performed. These results are in accordance with other studies suggesting that the adherence to a clear analgesia-based sedation protocol might be more important then the choice of medications itself.

Analgesics, Opioid↗
PubMed2003

Measurement of functional residual capacity by nitrogen washout during partial ventilatory support.

OBJECTIVE: Evaluation of an open circuit multiple breath nitrogen washout (MBNW) technique for measurement of functional residual capacity (FRC) during partial ventilatory support using corrections for gas viscosity, sampling delay time, and re-inspired nitrogen. DESIGN: Measurements in a lung model with known reference volume simulating spontaneous breathing and duplicate measurements in patients breathing spontaneously with partial ventilatory support. SETTING. Experimental laboratory and intensive care units of a university hospital. PATIENTS: Eighteen patients with acute respiratory failure. INTERVENTIONS: Change of FiO(2) from baseline to 1.0. MEASUREMENTS AND MAIN RESULTS: FRC was measured by MBNW during spontaneous breathing with continuous positive airway pressure, pressure support ventilation, proportional assist ventilation, automatic tube compensation, and airway pressure release ventilation. In the lung model, repeated measurements at three volumes were done with all partial ventilatory support modalities, and baseline FiO(2 )was varied with one mode and FRC. The mean of differences between MBNW (FRC(MBNW)) and reference was 28 ml (1.6%), and the 2.SD-interval was 84 ml (4.9%) for all modes. Measurements up to a baseline FiO(2) of 0.8 showed differences of 5 ml (-0.3%) and the 2.SD-interval of 38 ml (2.2%) between reference and FRC(MBNW). In 18 patients, 66 duplicate measurements revealed a mean difference of 30 ml (0.9%) with a coefficient of repeatability of 358 ml (13%) independent of ventilatory mode and chronological order. CONCLUSION: This study suggests that, using corrections for gas viscosity, sampling delay time, and re-inspired nitrogen, FRC can be determined with good repeatability in patients and good accuracy in a lung model during partial ventilatory support.

Adult↗