Induction of mitochondrial dysfunction in patients under cardiopulmonary by-pass: preliminary results.

OBJECTIVE: Cardiac surgery is often performed by cardiopulmonary by-pass (CPB), generally associated with organ dysfunction. The aim of this work was to determine if and how this phenomenon is related to mitochondrial damage. To this purpose, the effect of the addition of serum from CPB patients to human fibroblasts cultures on mitochondrial respiratory chain and oxidative phosphorylation (OXPHOS) activities was investigated. PATIENTS AND METHODS: Serum samples of five patients were obtained before (pre-CPB) and after 6 h CPB weaning (CPB). Mitochondrial OXPHOS activities were examined by polarographic and spectrophotometric assays, and reactive oxygen species (ROS) production was measured by a spectrofluorimeter. RESULTS: Addition of CPB serum to fibroblasts determined a decrease of mitochondrial oxygen consumption due to an inhibition of mitochondrial respiratory chain and some OXPHOS enzymes activities. This inhibition seems to be mainly related to a reduced activity of complex I. CONCLUSIONS: Our data represent the first translational research evidence showing that CPB determines mitochondrial dysfunction which leads to impairment of OXPHOX activities and to an increase in ROS production, compromising tissue bioenergetic efficiency.

Perioperative goal-directed therapy with uncalibrated pulse contour methods: impact on fluid management and postoperative outcome.

Previous meta-analyses suggest that perioperative goal-directed therapy (GDT) is useful to decrease postoperative morbidity. Most GDT studies analysed were done with pulmonary artery catheters, oesophageal Doppler and calibrated pulse contour methods. Uncalibrated pulse contour (uPC) techniques are an appealing alternative but their accuracy has been questioned. The effects of GDT on fluid management (volumes and volume variability) remain unclear. We performed a meta-analysis of randomized controlled trials investigating the effects of GDT with uPC methods on postoperative outcome. The primary endpoint was postoperative morbidity. Fluid volumes and fluid volume variability (standard deviation/mean) over the GDT period were also studied. Nineteen studies met the inclusion criteria (2159 patients). Postoperative morbidity was reduced with GDT (OR 0.46, 95% CI 0.30-0.70, P<0.001). The volume of colloids was higher [weighted mean difference (WMD) +345 ml, 95% CI 148-541 ml, P<0.001] and the volume of crystalloids was lower (WMD -429 ml, 95% CI -634 to -224 ml, P<0.01) in the GDT group than in the control group. However, the total volume of fluid (WMD -220 ml, 95% CI -590 to 150 ml, P=0.25) and the variability of fluid volume (34% vs 33%, P=0.98) were not affected by GDT. The use of GDT with uPC techniques was associated with a decrease in postoperative morbidity. It was not associated with an increase in total fluid volume nor with a decrease in fluid volume variability.

A systematic review and individual patient data meta-analysis on intra-abdominal hypertension in critically ill patients: the wake-up project. World initiative on Abdominal Hypertension Epidemiology, a Unifying Project (WAKE-Up!).

Intra-abdominal hypertension (IAH), defined as a pathologically increase in intraabdominal pressure, is commonly found in critically ill patients. While IAH has been associated with several abdominal as well as extra-abdominal conditions, few studies have examined the occurrence of IAH in relation to mortality. The aim of this paper was to evaluate the prognostic role of IAH and its risk factors at admission in critically ill patients across a wide range of settings and countries. An individual patient meta-analysis of all available data and a systematic review of published (in full or as abstract) medical databases and studies between 1996 and June 2012 were performed. The search was limited to "clinical trials" and "randomized controlled trials", "adults", using the terms "intra-abdominal pressure", "intraabdominal hypertension" combined with any of the terms "outcome" and "mortality". All together data on 2707 patients, representing 21 centers from 11 countries was obtained. Data on 1038 patients were not analysed because of the following exclusion criteria: no IAP value on admission (N.=712), absence of information on ICU outcome (N.=195), age <18 or >95 years (N.=131). Data from 1669 individual patients (19 centers from 9 countries) were analyzed in the meta-analysis. Presence of IAH was defined as a sustained increase in IAP equal to or above 12 mmHg. At admission the mean overall IAP was 9.9±5.0 mmHg, with 463 patients (27.7%) presenting IAH with a mean IAP of 16.3±3.4 mmHg. The only independent predictors for IAH were SOFA score and fluid balance on the day of admission. Five hundred thirteen patients (30.8%) died in intensive care. The independent predictors for intensive care mortality were IAH, SAPS II score, SOFA score and admission category. This systematic review and individual patient data meta-analysis shows that IAH is frequently present in critically ill patients and it is an independent predictor for mortality.

A Systematic Review And Individual Patient Data Meta-Analysis On Intraabdominal Hypertension In Critically Ill Patients: The Wake-Up Project World Initiative on Abdominal Hypertension Epidemiology, a Unifying Project (WAKE-Up!).

Background: Intraabdominal hypertension (IAH), defined as a pathologically increase in intraabdominal pressure, is commonly found in critically ill patients. While IAH has been associated with several abdominal as well as extra-abdominal conditions, few studies have examined the occurrence of IAH in relation to mortality. Objective: To evaluate the prognostic role of IAH and its risk factors at admission in critically ill patients across a wide range of settings and countries. Data sources: An individual patient meta-analysis of all available data and a systematic review of published (in full or as abstract) medical databases and studies between 1996 and June 2012 were performed. The search was limited to "clinical trials" and "randomized controlled trials", "adults", using the terms "intraabdominal pressure", "intraabdominal hypertension" combined with any of the terms "outcome" and "mortality". All together data on 2707 patients, representing 21 centers from 11 countries was obtained. Data on 1038 patients were not analysed because of the following exclusion criteria: no IAP value on admission (n=712), absence of information on ICU outcome (n=195), age <18 or > 95 years (n=131). Results: Data from 1669 individual patients (19 centers from 9 countries) were analyzed in the meta-analysis. Presence of IAH was defined as a sustained increase in IAP equal to or above 12 mmHg. At admission the mean overall IAP was 9.9±5.0 mmHg, with 463 patients (27.7%) presenting IAH with a mean IAP of 16.3±3.4 mmHg. The only independent predictors for IAH were SOFA score and fluid balance on the day of admission. Five hundred thirteen patients (30.8%) died in intensive care. The independent predictors for intensive care mortality were IAH, SAPS II score, SOFA score and admission category. Conclusions: This systematic review and individual patient data meta-analysis shows that IAH is frequently present in critically ill patients and it is an independent predictor for mortality.

Gaze-controlled, computer-assisted communication in Intensive Care Unit: "speaking through the eyes".

BACKGROUND: The aim of this study was to test the hypothesis that a gaze-controlled communication system (eye tracker, ET) can improve communication processes between completely dysarthric ICU patients and the hospital staff, in three main domains: 1) basic communication processes (i.e., fundamental needs, desire, and wishes); 2) the ability of the medical staff to understand the clinical condition of the patient; and 3) the level of frustration experienced by patient, nurses and physicians. METHODS: Fifteen fully conscious medical and surgical patients, 8 physicians, and 15 nurses were included in the study. The experimental procedure was composed by three phases: in phase 1 all groups completed the preintervention questionnaire; in phase 2 the ET was introduced and tested as a communication device; in phase 3 all groups completed the postintervention questionnaire. RESULTS: Patients preintervention questionnaires showed remarkable communication deficits, without any group effect. Answers of physicians and nurses were pretty much similar to the one of patients. Postintervention questionnaires showed in all groups a remarkable and statistically significant improvement in different communication domains, as well as a remarkable decrease of anxiety and disphoric thought. Improvement was also reported by physicians and nurses in their ability to understand patient's clinical conditions. CONCLUSION: Our results show an improvement in the quality of the examined parameters. Better communication processes seem also to lead to improvements in several psychological parameters, namely anxiety and drop-out depression perceived by both patients and medical staff. Further controlled studies are needed to define the ET role in ICU.

Prospective multicenter study on epidemiology of acute kidney injury in the ICU: a critical care nephrology Italian collaborative effort (NEFROINT).

Acute kidney injury (AKI) is an independent risk factor for mortality in critically ill patients whose epidemiology has been made unclear in the past by the use of different definitions across various studies. The RIFLE consensus definition has provided a unifying definition for AKI leading to large retrospective studies in different countries. The present study is a prospective observational multicenter study designed to prospectively evaluate all incident admissions in 10 Intensive Care Units (ICUs) in Italy and the relevant epidemiology of AKI. A simple user-friendly web-based data collection tool was created with the scope to serve for this study and to facilitate future multicenter collaborative efforts. We enrolled 601 consecutive patients into the study; 25 patients with End-Stage Renal Disease were excluded leaving 576 patients for analysis. The median age was 66 (IQR 53-76) years, 59.4% were male, while median SAPS II and APACHE II scores were 43 (IQR 35-54) and 18 (IQR 13-24), respectively. The most common diagnostic categories for ICU admission were: respiratory (27.4%), followed by neurologic (17%), trauma (14.4%), and cardiovascular (12.1%). Crude ICU and hospital mortality were 21.7% and median ICU length of stay was 5 days (IQR 3, 14). Of 576 patients, 246 patients (42.7%) had AKI within 24 hours of ICU admission while 133 developed new AKI later during their ICU stay. RIFLE-initial class was Risk in 205 patients (54.1%), Injury in 99 (26.1%) and Failure in 75 (19.8%). Progression of AKI to a worse RIFLE class was seen in 114 patients (30.8% of AKI patients). AKI patients were older, with higher frequency of common risk factors. 116 AKI patients (30.6%) fulfilled criteria for sepsis during their ICU stay, compared to 33 (16.7%) of non-AKI patients (P<0.001). 48 patients (8.3%) were treated with renal replacement therapy (RRT) in the ICU. Patients were started on RRT a median of 2 (IQR 0-6) days after ICU admission. Among AKI patients, they were started on RRT a median of 1 (IQR 0-4) days after fulfilling criteria for AKI. Median duration of RRT was 5 (IQR 2-10) day. AKI patients had a higher crude ICU mortality (28.8% vs. non-AKI 8.1%, P<0.001) and longer ICU length of stay (median 7 days vs. 3 days [non-AKI], P<0.001). Crude ICU mortality and ICU length of stay increased with greater severity of AKI. Two hundred twenty five patients (59.4% of AKI patients) had complete recovery of renal function, with a SCr at time of ICU discharge which was ≤120% of baseline; an additional 51 AKI patients (13.5%) had partial renal recovery, while 103 (27.2%) had not recovered renal function at the time of death or ICU discharge. Septic patients had more severe AKI, and were more likely to receive RRT with less frequency of renal function recovery. Patients with sepsis had higher ICU mortality and longer ICU stay. The study confirms previous analyses describing RIFLE as an optimal classification system to stage AKI severity. AKI is indeed a deadly complication for ICU patients where the level of severity correlated with mortality and length of stay. The tool developed for data collection resulted user friendly and easy to implement. Some of its features including a RIFLE class alert system, may help the treating physician to collect systematically AKI data in the ICU and possibly may guide specific decision on the institution of renal replacement therapy.

A fatal rhino-cerebral zygomycosis in a young woman with latent diabetes mellitus and cerebral blood vessel agenesis.

Rhino-cerebral zygomycosis (RCZ) is an acute rapidly progressive fungal infection usually occurring in patients with diabetes mellitus and ketoacidosis. Patients typically complain of pain located in the facial, nasal or orbital regions, followed by sudden blindness and cranial nerve palsy. Early diagnosis, correction of risk factors, prompt surgical removal and aggressive antifungal therapy are warranted as life-saving treatments. The following report describes a case of a lethal RCZ which occurred in an apparently healthy woman with latent non-decompensated diabetes mellitus and a fetal-type posterior (FTP) circle of Willis.

Goal-directed haemodynamic therapy and gastrointestinal complications in major surgery: a meta-analysis of randomized controlled trials.

Postoperative gastrointestinal (GI) dysfunction is one of the most frequent complications in surgical patients. Most cases are associated with episodes of splanchnic hypoperfusion due to hypovolaemia or cardiac dysfunction. It has been suggested that perioperative haemodynamic goal-directed therapy (GDT) may reduce the incidence of these complications in cardiac surgery, and other surgery, but clear evidence is lacking. We have undertaken a meta-analysis of the effects of GDT on postoperative GI and liver complications. A systematic search, using MEDLINE, EMBASE, and The Cochrane Library databases, was performed. Sixteen randomized controlled trials (3410 participants) met the inclusion criteria. Data synthesis was obtained using odds ratio (OR) with 95% confidence interval (CI) by random-effects model. Statistical heterogeneity was assessed by Q and I2 statistics. GI complications were ranked as major (required radiological or surgical intervention or life-threatening condition) or minor (no or only pharmacological treatment required). Major GI complications were significantly reduced by GDT when compared with a control group (OR, 0.42; 95% CI, 0.27-0.65). Minor GI complications were also significantly decreased in the GDT group (OR, 0.29; 95% CI, 0.17-0.50). Treatment did not reduce hepatic injury rate (OR, 0.54; 95% CI, 0.19-1.55). Quality sensitive analyses confirmed the main overall results. In patients undergoing major surgery, GDT, by maintaining an adequate systemic oxygenation, can protect organs particularly at risk of perioperative hypoperfusion and is effective in reducing GI complications.

Abdominal hypertension and liver dysfunction in intensive care unit patients: an "on-off" phenomenon?

Intra-abdominal hypertension (IAH) can affect liver hemodynamics but it is not known if has a significant clinical impact on liver function. The aim of this study was to investigate the relationship between IAH and liver function. A prospective study was performed in 110 adult intensive care unit (ICU) patients. Intra-abdominal pressure (IAP) was measured on admission and every other day, and liver sequential organ failure assessment (SOFA) score was collected whenever IAP was measured. IAH was defined by a IAP >or= 10 mm Hg, and liver dysfunction was defined by a hepatic SOFA score >or= 2. An overall IAH incidence of 56.3% was found (n = 62). Thirty-three patients presented a liver SOFA score >or= 2, with an overall incidence of 30%. Liver SOFA score of the group of patients with abdominal hypertension was higher than in group of patients without abdominal hypertension. (0.8 +/- 1.05 vs 0.4 +/- 0.7; P < .05), but IAH and liver dysfunction were not significantly associated (chi2 = 2.03; P = .15). When the whole sample was divided according to the worst IAP score (IAP < 10, IAP between 10 and 15, and IAP > 15), the corresponding liver dysfunction scores in the three groups were 0.35 +/- 0.6, 0.74 +/- 1, and 1.2 +/- 1.3, respectively (P = .01). A strict association between IAH and liver dysfunction was not found. Most likely, low levels of IAH, although able to reduce liver blood flow, are not per se sufficient to produce a real dysfunction; however, a correlation between the degree of IAH and the degree of hyperbilirubinemia exists. IAH does not seem to be an "on-off" phenomenon, but produces liver alterations for increasing levels of its severity.

Independent lung ventilation in patients with unilateral pulmonary contusion. Monitoring with compliance and EtCO(2).

OBJECTIVE: a) to describe a non-barotraumatic ventilatory setting for independent lung ventilation (ILV); b) to determine the utility of single lung end-tidal CO(2) (EtCO(2)) monitoring to evaluate the ventilation to perfusion (V/Q) matching in each lung during ILV and for ILV weaning. DESIGN: prospective study. SETTING: general intensive care unit in a university teaching hospital. PATIENTS: twelve patients with unilateral thoracic trauma needing ILV. INTERVENTIONS AND RESULTS: ILV was started with each lung ventilated with the same tidal volume (Vt): plateau airway pressure (Pplat) was 34.2+/-3.2 cmH2O in diseased lungs (DL) and 18.1+/-1.9 cmH2O in normal lungs (NL) ( P<0.01). Static compliance (Cst) was 9.9+/-1.1 ml/cmH(2)O in DL and 19.3+/-1.7 ml/cmH(2)O in NL ( P<0.01). EtCO2 was 22.5+/-2.2 mmHg in DL and 36.6+/-1.9 mmHg in NL ( P<0.01). PaO(2)/FiO(2) was at 151+/-20. PEEP was applied on the DL and each lung was ventilated with a Vt that developed Pplat < or =26 cmH2O. With this setting, Vt given to the NL was unchanged, whereas it was reduced in the DL (238+/-30 ml vs 350+/-31 ml; P<0.01). Cst and EtCO2 were still significantly lower in the DL ( P<0.01, respectively), while the PaO(2)/FiO(2) ratio remained unchanged. Vt was then progressively increased in the DL as Pplat decreased, but remained unchanged in the NL. ILV was discontinued when Vt, Cst and EtCO(2) were the same in each lung. PaO(2)/FiO(2) ratio had then increased to 295+/-18. CONCLUSIONS: a) during ILV, adequate oxygenation and a reduction in V/Q mismatch can be obtained by setting Vt and PEEP to keep Pplat below a safe threshold for barotrauma; b) measurement of single lung EtCO2 can be useful to evaluate progressive V/Q matching.

Impairment of lung and chest wall mechanics in patients with acute respiratory distress syndrome: role of abdominal distension.

Recent data have suggested that the elastic properties of the chest wall (CW) may be compromised in patients with ARDS because of abdominal distension (4). We partitioned CW and lung (L) mechanics, assessed the role of abdominal distension, and verified whether the underlying disease responsible for ARDS affects the impairment of respiratory mechanics. Volume-pressure (V-P) curves (interrupter technique) were assessed in nine patients with surgical ARDS and nine patients with medical ARDS. Relative to nine patients undergoing heart surgery, V-P curves of the respiratory system (rs) and L of patients with surgical or medical ARDS showed a rightward displacement. V-P curves of the CW and the L showed an upward concavity in patients with medical ARDS and a downward concavity in patients with surgical ARDS. Although the CW and the abdomen (abd) V-P curves in patients with medical ARDS were similar to those obtained in patients undergoing heart surgery, they showed a rightward shift and a downward flattening in patients with surgical ARDS. In five of these patients, a reduction in static end-inspiratory pressure of the abd (69+/-4%), rs (30+/-3%), CW (41+/-2%), and L (27+/-3%) was observed after abdominal decompression for acute bleeding. Abdominal decompression therefore caused an upward and leftward shift of the V-P curves of the respiratory system, chest wall, lung, and abdomen. In conclusion we showed that impairment of the elastic properties of the respiratory system may vary with the underlying disease responsible for ARDS. The flattening of the V-P curve at high pressures observed in some patients with ARDS may be due to an increase in chest wall elastance related to abdominal distension. These observations have implications for the assessment and ventilatory management of patients with ARDS.

Multiplane transesophageal echocardiography to detect effectiveness of selective pulmonary recombinant tissue-type plasminogen activator thrombolysis in pulmonary embolism and patent foramen ovale.

A functionally patent foramen ovale can create a relevant right-to-left shunt during massive pulmonary embolism. This associated feature, although maintaining adequate cardiac output, may explain both the paradoxic embolism and the uneffectiveness of peripherally administered drugs. This case demonstrates the potential of transesophageal echocardiography in monitoring the hemodynamic findings of such patients and, consequently, the effectiveness of thrombolytic treatment.

Effects of positive end-expiratory pressure on right ventricular function in COPD patients during acute ventilatory failure.

OBJECTIVE: To examine the effects of external positive end-expiratory pressure (PEEP) on right ventricular function in chronic obstructive pulmonary disease (COPD) patients with intrinsic PEEP (PEEPi). DESIGN: Prospective study. SETTING: General intensive care unit in a university teaching hospital. PATIENTS: Seven mechanically ventilated flow-limited COPD patients (PEEPi = 9.7 +/- 1.3 cmH2O, mean +/- SD) with acute respiratory failure. INTERVENTION: Hemodynamic and respiratory mechanic data were collected at four different levels of PEEP (0-5-10-15 cmH2O). MEASUREMENTS AND RESULTS: Hemodynamic parameters were obtained by a Swan-Ganz catheter with a fast response thermistor. Cardiac index (CI) and end-expiratory lung volume (EELV) reductions started simultaneously when the applied PEEP was approximately 90% of PEEPi measured on 0 cmH2O (ZEEP). Changes in transmural intrathoracic pressure (PEEPi,cw) started only at a PEEP value much higher (120%) than PEEPi. The reduction in CI was related to a decrease in the right end-diastolic ventricular volume index (RVEDVI) (r = 0.61; p < 0.001). No correlation between CI and transmural right atrial pressure was observed. The RVEDVI was inversely correlated with PEEP-induced changes in EELV (r = -55; p < 0.001), but no with PEEPi,cw (r = -0.08; NS). The relationship between RVEDVI and right ventricular stroke work index, considered an index of contractility, was significant in three patients, i.e., PEEP did not change contractility. In the other patients, an increase in contractility seemed to occur. CONCLUSIONS: In COPD patients an external PEEP exceeding 90% of PEEPi causes lung hyperinflation and reduces the CI due to a preload effect. The reduction in RVEDVI seems related to changes in EELV, rather than to changes in transmural pressures, suggesting a lung/heart volume interaction in the cardiac fossa. Thus, in COPD patients, application of an external PEEP level lower than PEEPi may affect right ventricular function.

Endotoxic shock alters distribution of blood flow within the intestinal wall.

OBJECTIVE: To investigate whether a redistribution of blood flow from the mucosa to the muscular layer of the intestinal wall contributes to the observed increased arterial-mucosal Pco2 gradient and the decreased mucosal tonometric pH during endotoxic shock. DESIGN: A prospective, controlled, animal study. SETTING: Animal laboratory in a university medical center. SUBJECTS: Ten domestic pigs. INTERVENTIONS: Pigs were anesthetized with ketamine and pentobarbital, mechanically ventilated, hemodynamically monitored, and then challenged with Escherichia coli endotoxin (10 micrograms/ kg i.v.). MEASUREMENTS AND MAIN RESULTS: Cardiac output, mesenteric artery blood flow, and systemic, pulmonary, and portal pressures were measured. Intestinal mucosa tonometric Pco2 and pH were determined with saline-filled balloon tonometers. The tissue blood flow to the mucosa and the muscular layer were independently measured with colored microspheres, using the arterial reference sample method. Thus, total intestinal blood flow was evaluated with respect to its transmural (mucosa vs. muscularis) and geographical (proximal jejunum, mid-small intestine, and terminal ileum) distribution. Endotoxin administration with fluid resuscitation induced a distributive shock with a decrease in intestinal mucosa tonometric pH. Under endotoxemic conditions, the mucosal flow increased in each geographical area, with the increase being larger proximally in the jejunum than distally in the ileum. The mucosal tonometric pH was found to correlate inversely with mucosal blood flow. The increase in blood flow to the mucosa was balanced by a decrease in blood flow to the muscularis, with total mesenteric flow remaining unchanged. CONCLUSIONS: Mucosal hypoperfusion does not account for the acidotic mucosal tonometric pH in endotoxic shock. The results suggest either a primary cytotoxic effect or an enhanced counter-current-mediated hypoxic insult in the apical villus. The decrease in blood flow to the muscularis may contribute to loss of intestinal wall peristaltic activity and structural wall integrity.

Right ventricular myocardial function in ARF patients. PEEP as a challenge for the right heart.

OBJECTIVE: To examine the hemodynamic effects of external positive end-expiratory pressure (PEEP) on right ventricular (RV) function in acute respiratory failure (ARF) patients. DESIGN: Prospective, with retrospective analysis on the basis of RV volume response to PEEP. SETTING: General intensive care unit in a university teaching hospital. PATIENTS: 20 mechanically ventilated ARF patients (mean lung injury score = 2.6 +/- 0.45 SD). INTERVENTION: Incremental levels of PEEP (0-5-10-15 cmH2O) were applied and RV hemodynamics were studied by means of a Swan-Ganz catheter with a fast-response thermistor for right ventricular ejection fraction (RVEF) measurement. According to their response to PEEP 15, two groups of patients were defined: group A (9 patients) with unchanged or increased RV end-diastolic volume index (RVEDVI) and group B (11 patients) with decreased RVEDVI. MEASUREMENTS AND RESULTS: At zero PEEP (ZEEP) the hemodynamic parameters of the two groups did not differ. In group A, cardiac index (CI) and stroke volume index (SI) decreased at all PEEP levels (5, 10, and 15 cmH2O), while RVEF started to decrease only at a PEEP of 10 cmH2O (-10.8%), and RVES(systolic)VI increased only at PEEP 15 cmH2O (+21.5%). RVEDVI was not affected by PEEP. In group B, CI and SI decreased at all PEEP levels (5, 10, and 15 cmH2O). Similarly, RVEDVI started to decrease at PEEP 5 cmH2O, while RVESVI decreased only at PEEP 15 cmH2O (-21.4%). RVEF was not affected by PEEP in this group. In each patient the slope of the relationship between RVEDVI and right ventricular stroke work index (RVSWI), expressing RV myocardial performance, was studied. This relationship was significant (no change in RV contractility) in 8 of 11 patients in group B and in only 2 patients in group A. In 4 patients in group A, PEEP shifted the RVSWI/RVEDVI ratio rightward in the plot, indicating a decrease in RV myocardial performance in these patients. CONCLUSIONS: PEEP affects RV function in ARF patients. The decrease in cardiac output is more often associated with a preload decrease and no change in RV contractility. On the other hand, the finding of increased RV volumes with PEEP may be associated with a reduction in RV myocardial performance. Thus, these results suggest that assessment of RV function by PEEP and preload recruitable stroke work may disclose otherwise unpredictable alterations in RV function.

[Effects of PEEP on intrathoracic and extrathoracic blood volumes evaluated with the COLD system in patients with acute respiratory failure. Preliminary study]. / Effetti della PEEP sui volumi ematici intratoracico e totale valutai con sistema COLD in pazienti con insufficienza respiratoria acuta. Studio preliminare.

AIM OF THE STUDY: To evaluate the effects of positive end expiratory pressure (PEEP) on intrathoracic and extrathoracic blood volumes in patients with acute respiratory failure (ARF). METHODS: In 4 ARF patients, we have measured cardiac output (CI), intrathoracic blood volume (ITBVI), global end-diastolic ventricular volume (GEDVI), pulmonary (PBVI) and total (TBVI) blood volumes, during application of two PEEP levels (0 and 10 cm H2O). These measurements have been performed by PULSION COLD Z-021 system, using the double indicator dilution technique (thermal and dye dilution). RESULTS: PEEP application caused a significant reduction in CI (from 3.8 +/- 0.4 to 2.9 +/- 0.1 1/min/m2) and ITBVI (from 888 +/- 48 to 698 +/- 25 ml/m2). The reduction in intrathoracic blood volume was associated with a significant reduction in GEDVI and PBVI. After PEEP application, there was a significant reduction in TBVI (from 2437 +/- 135 to 1984 +/- 49 ml/m2). CONCLUSIONS: PEEP application decreases cardiac index, mainly through a preload reduction, as evidenced by the reduction in intrathoracic and end-diastolic ventricular blood volumes. The preload effect is due to an increase in intrathoracic pressure with reduction in total circulating blood volume. TBVI reduction is consistent with blood pooling in vascular compartments, e.g., splanchnic compartment, characterized by long vascular time constant.