Cardiopulmonary interactions in acute lung injury

PURPOSE OF REVIEW

Through shared anatomy, pressures, and endothelial connections, the respiratory and cardiovascular systems affect each other in complex but clinically important ways.

RECENT FINDINGS

Lung injury has clinically important circulatory effects, especially with regards to right ventricular function. Mechanical ventilation and PEEP produce a host of circulatory consequences, some beneficial, some life-threatening. At the same time, circulatory impairments and treatments can magnify the impact of lung failure.

SUMMARY

Cardiopulmonary interactions underpin current views of fluid management and mechanical ventilation. Understanding cardiopulmonary interactions and their physiological basis has direct clinical relevance.

Applying dynamic parameters to predict hemodynamic response to volume expansion in spontaneously breathing patients with septic shock

Volume expansion is a mainstay of therapy in septic shock, although its effect is difficult to predict using conventional measurements. Dynamic parameters, which vary with respiratory changes, appear to predict hemodynamic response to fluid challenge in mechanically ventilated, paralyzed patients. Whether they predict response in patients who are free from mechanical ventilation is unknown. We hypothesized that dynamic parameters would be predictive in patients not receiving mechanical ventilation. This is a prospective, observational, pilot study. Patients with early septic shock and who were not receiving mechanical ventilation received 10-mL/kg volume expansion (VE) at their treating physician's discretion after initial resuscitation in the emergency department. We used transthoracic echocardiography to measure vena cava collapsibility index and aortic velocity variation before VE. We used a pulse contour analysis device to measure stroke volume variation (SVV). Cardiac index was measured immediately before and after VE using transthoracic echocardiography. Hemodynamic response was defined as an increase in cardiac index 15% or greater. Fourteen patients received VE, five of whom demonstrated a hemodynamic response. Vena cava collapsibility index and SVV were predictive (area under the curve = 0.83, 0.92, respectively). Optimal thresholds were calculated: vena cava collapsibility index, 15% or greater (positive predictive value, 62%; negative predictive value, 100%; P = 0.03); SVV, 17% or greater (positive predictive value 100%, negative predictive value 82%, P = 0.03). Aortic velocity variation was not predictive. Vena cava collapsibility index and SVV predict hemodynamic response to fluid challenge patients with septic shock who are not mechanically ventilated. Optimal thresholds differ from those described in mechanically ventilated patients.

[Fluid therapy in cardiac surgery. An update]

The anesthetist has 2 major tools for optimizing haemodynamics in cardiac surgery: Vasoactive drugs and the intravascular volume. It is necessary to identify which patients would benefit from one or the other therapies for a suitable response to treatment. Hemodynamic monitoring with the different existing parameters (pressure, volumetric static, volumetric functional and echocardiography) allows the management of these patients to be optimized. In this article a review is presented on the most recent and relevant publications, and the different tools available to control the management of the fluid therapy in this context, and to suggest a few guidelines for the haemodynamics monitoring of patients submitted to cardiac surgery. A systematic search has been made in PubMed, limiting the results to the publications over the last five years up to February 2012.

Respiratory change in ECG-wave amplitude is a reliable parameter to estimate intravascular volume status

Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The "Brody effect", a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS amplitude (ECGmax) and minimal QRS amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax - ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both <12 %. ΔPP were significantly correlated with ΔECG (r(2) = 0.89, p < 0.001). Volume loss induced by haemorrhage increased significantly ΔPP and ΔECG. Moreover, during this state, ΔPP were significantly correlated with ΔECG (r(2) = 0.86, p < 0.001). Re-transfusion significantly decreased ΔPP and ΔECG, and ΔPP were significantly correlated with ΔECG (r(2) = 0.90, p < 0.001). The observed correlations between ΔPP and ΔECG at each time point of the study suggest that ΔECG is a reliable parameter to estimate the changes in intravascular volume status and provide experimental confirmation of the "Brody effect."

SEMICYUC 2012. Recommendations for intensive care management of acute pancreatitis

OBJECTIVE

Significant changes in the management of acute pancreatitis have taken place since the 2004 Pamplona Consensus Conference. The objective of this conference has been the revision and updating of the Conference recommendations, in order to unify the integral management of potentially severe acute pancreatitis in an ICU.

PARTICIPANTS

Spanish and international intensive medicine physicians, radiologists, surgeons, gastroenterologists, emergency care physicians and other physicians involved in the treatment of acute pancreatitis. LEVELS OF EVIDENCE AND GRADES OF RECOMMENDATION: The GRADE method has been used for drawing them up. DRAWING UP THE RECOMMENDATIONS: The selection of the committee members was performed by means of a public announcement. The bibliography has been revised from 2004 to the present day and 16 blocks of questions on acute pancreatitis in a ICU have been drawn up. Firstly, all the questions according to groups have been drawn up in order to prepare one document. This document has been debated and agreed upon by computer at the SEMICYUC Congress and lastly at the Consensus Conference which was held with the sole objective of drawing up these recommendations.

CONCLUSIONS

Eighty two recommendations for acute pancreatitis management in an ICU have been presented. Of these 84 recommendations, we would emphasize the new determinants-based classification of acute pancreatitis severity, new surgical techniques and nutritional recommendations. Note. This summary only lists the 84 recommendations of the 16 questions blocks except blocks greater relevance and impact of its novelty or because they modify the current management.

Sepsis-induced cardiomyopathy

Myocardial dysfunction is one of the main predictors of poor outcome in septic patients, with mortality rates next to 70%. During the sepsis-induced myocardial dysfunction, both ventricles can dilate and diminish its ejection fraction, having less response to fluid resuscitation and catecholamines, but typically is assumed to be reversible within 7-10 days. In the last 30 years, It´s being subject of substantial research; however no explanation of its etiopathogenesis or effective treatment have been proved yet. The aim of this manuscript is to review on the most relevant aspects of the sepsis-induced myocardial dysfunction, discuss its clinical presentation, pathophysiology, etiopathogenesis, diagnostic tools and therapeutic strategies proposed in recent years.

Bench-to-bedside review: functional hemodynamics during surgery - should it be used for all high-risk cases?

The administration of a fluid bolus is done frequently in the perioperative period to increase the cardiac output. Yet fluid loading fails to increase the cardiac output in more than 50% of critically ill and surgical patients. The assessment of fluid responsiveness (the slope of the left ventricular function curve) prior to fluid administration may thus not only help in detecting patients in need of fluids but may also prevent unnecessary and harmful fluid overload. Unfortunately, commonly used hemodynamic parameters, including the cardiac output itself, are poor predictors of fluid responsiveness, which is best assessed by functional hemodynamic parameters. These dynamic parameters reflect the response of cardiac output to a preload-modifying maneuver (for example, a mechanical breath or passive leg-raising), thus providing information about fluid responsiveness without the actual administration of fluids. All dynamic parameters, which include the respiratory variations in systolic blood pressure, pulse pressure, stroke volume and plethysmographic waveform, have been repeatedly shown to be superior to commonly used static preload parameters in predicting the response to fluid loading. Within their respective limitations, functional hemodynamic parameters should be used to guide fluid therapy as part of or independently of goal-directed therapy strategies in the perioperative period.

Prediction of fluid responsiveness in patients admitted to the medical intensive care unit

PURPOSE

Accurate prediction of fluid responsiveness is of importance in the treatment of patients admitted to the intensive care unit (ICU). We investigated whether physical examination, central venous pressure (CVP), central venous oxygen saturation (ScvO2), passive leg raising (PLR) test, and transpulmonary thermodilution (TPTD)-derived parameters can predict volume responsiveness in patients admitted to the ICU.

MATERIALS AND METHODS

In this prospective study, structured clinical examination, measurement of CVP and ScvO2, a PLR test, and TPTD measurements were performed in 31 patients. A fluid challenge test was performed in 24 patients (fluid responsiveness was defined as a cardiac index [CI] increase of ≥ 15%).

RESULTS

Physical examination, CVP, ScvO2, the PLR test, and the TPTD-derived volumetric preload parameter global end-diastolic volume index showed poor prognostic capabilities regarding prediction of fluid responsiveness. Twenty-nine percent of patients were fluid responsive. There was a statistically significant correlation between the fluid challenge-induced increase in CI and changes in global end-diastolic volume index (r = 0.666, P < .001). In only 17% of patients, CI did not increase after fluid loading.

CONCLUSIONS

Prediction of fluid responsiveness is difficult using physical examination, CVP, ScvO2, PLR maneuver, or TPTD-derived variables in critically ill patients. A volume challenge test should be considered for the assessment of fluid responsiveness in critically ill patients admitted to the ICU.

Evaluation of a polymerase chain reaction assay for pathogen detection in septic patients under routine condition: an observational study

Background

Treatment of septic shock relies on appropriate antimicrobial therapy. Current culture based methods deliver final results after days, which may delay potentially lifesaving adjustments in antimicrobial therapy. This study was undertaken to compare PCR with blood culture results under routine conditions regarding 1. impact on antimicrobial therapy, and 2. time to result, in patients with presumed sepsis.

Methodology/Principal Findings

This was an observational study in a 50 beds ICU of a university hospital. In 245 patients with suspected sepsis, 311 concomitant blood cultures and blood for multiplex PCR (VYOO®) were obtained. 45 of 311 blood cultures (14.5%) and 94 of 311 PCRs (30.1%) were positive. However, blood culture or microbiological sampling from the presumed site of infection rarely confirmed PCR results and vice versa. Median time to positivity and interquartile range were 24.2 (18.0, 27.5) hours for the PCR and 68 (52.2, 88.5) hours for BC (p<0.01). PCR median time to result was dependent on technician availability (53.5 hours on Saturdays, 7.2 hours under optimal logistic conditions). PCR results showed good correlation with procalcitonin (p<0.001). In 34% of patients with positive PCRs antimicrobial therapy was considered inadequate according to assessment of clinical arbitrators including 5 patients with vancomycin-resistant enterococci (VRE), 3 cases with multiresistant staphylococci, and 4 patients with fungi.

Conclusions

The results of this observational study support the hypothesis that PCR results are available faster, are more frequently positive, and may result in earlier adjustment of antimicrobial therapy. However, shorter time to result can only be fully exploited when the laboratory is adequately staffed for a 24 hour/7 day service, or when point of care/automated assay systems become available.

Assessment of an uncalibrated pressure waveform device's ability to track cardiac output changes due to norepinephrine dose adjustments in patients with septic shock: a comparison with Doppler echocardiography

OBJECTIVES

The FloTrac Vigileo (FTV) estimates cardiac output (CO) on the basis of an uncalibrated arterial pressure waveform. To assess the ability of the third-generation of FTV (v.3.02) to track changes in CO following norepinephrine dose adjustment in patients with septic shock, we performed a comparative study using Doppler echocardiography (DE).

STUDY DESIGN

Prospective observational study.

PATIENTS

We prospectively included 20 mechanically ventilated patients receiving norepinephrine and monitored with the FTV. Five minutes after each change in norepinephrine dose (decided by the attending physician), CO was measured simultaneously with the FTV (CO(FTV)) and DE (CO(DE)). The changes in CO were compared. ROC curves were built to assess the ability of FTV to detect significant changes in CO(DE) of at least 15%.

RESULTS

Ninety pairs of CO variations measurements were made. The intertechnique correlation coefficient for changes in CO of at least 15% was r=0.59; P=0.0009. The AUC of a ROC curve built to test the FTV's ability to detect a CO(DE) increase of 15% or more was 0.783 (±0.083) (P=0.005). A CO(FTV) threshold value of 15% had a sensitivity of 54% (25-81) and a specificity of 87% (77-94). For a CO(DE) decrease of 15% or more, the ROC curve had an AUC of 0.616 (±0.075) (P=0.12) and a CO(FTV) threshold value of 13% yielded a sensitivity of 53% (27-79) and a specificity of 72% (60-82).

CONCLUSIONS

The FTV was unable to accurately track changes in CO following norepinephrine dose adjustments in critically ill patients with septic shock.

Improvement of left ventricular relaxation as assessed by tissue Doppler imaging in fluid-responsive critically ill septic patients

PURPOSE

Left ventricular (LV) diastolic function is often impaired in critically ill septic patients. The peak velocity of the mitral annulus early wave during diastole (E'), measured by Doppler echocardiography, is a major tool to evaluate LV relaxation, the ATP-dependent part of diastole. The authors hypothesized that if volume expansion (VE) is followed by an increase in stroke volume (SV) ("adequate" VE), LV relaxation and consequently E' may be increased.

METHODS

This was a prospective study in which 83 mechanically ventilated septic patients with circulatory failure were enrolled. Doppler echocardiography was performed before and after the infusion of 500 ml of saline over 20 min. Patients were then classified into two groups according to their response to VE: responders (R) were those in whom SV increased by at least 15 %; all others were considered to be non-responders (NR). SV, mitral flow early wave velocity (E), E' and the E/E' ratio were measured before and after VE. VE-induced variations (∆) in all parameters were compared in R and NR. Patients with an E' < 0.12 m/s were considered to have LV diastolic dysfunction.

RESULTS

Fifty-nine patients (71 %) were R and 24 (29 %) were NR. Fifty-six percent of R patients and 58 % of NR patients had LV diastolic dysfunction. For patients with LV diastolic dysfunction (n = 47), ∆E' was significantly higher in the R group (29 ± 5 vs. 5 ± 8 %; p = 0.01) whilst ∆E/E' was higher in the NR group (35 ± 9 vs. 2 ± 6 %; p = 0.02).

CONCLUSIONS

E' maximal velocity increased with adequate VE, suggesting an improvement of LV relaxation with the correction of hypovolaemia in patients with septic shock.

613 cases of splenic rupture without risk factors or previously diagnosed disease: a systematic review

BACKGROUND

Rupture of the spleen in the absence of trauma or previously diagnosed disease is largely ignored in the emergency literature and is often not documented as such in journals from other fields. We have conducted a systematic review of the literature to highlight the surprisingly frequent occurrence of this phenomenon and to document the diversity of diseases that can present in this fashion.

METHODS

Systematic review of English and French language publications catalogued in Pubmed, Embase and CINAHL between 1950 and 2011.

RESULTS

We found 613 cases of splenic rupture meeting the criteria above, 327 of which occurred as the presenting complaint of an underlying disease and 112 of which occurred following a medical procedure. Rupture appeared to occur spontaneously in histologically normal (but not necessarily normal size) spleens in 35 cases and after minor trauma in 23 cases. Medications were implicated in 47 cases, a splenic or adjacent anatomical abnormality in 31 cases and pregnancy or its complications in 38 cases. The most common associated diseases were infectious (n = 143), haematologic (n = 84) and non-haematologic neoplasms (n = 48). Amyloidosis (n = 24), internal trauma such as cough or vomiting (n = 17) and rheumatologic diseases (n = 10) are less frequently reported. Colonoscopy (n = 87) was the procedure reported most frequently as a cause of rupture. The anatomic abnormalities associated with rupture include splenic cysts (n = 6), infarction (n = 6) and hamartomata (n = 5). Medications associated with rupture include anticoagulants (n = 21), thrombolytics (n = 13) and recombinant G-CSF (n = 10). Other causes or associations reported very infrequently include other endoscopy, pulmonary, cardiac or abdominal surgery, hysterectomy, peliosis, empyema, remote pancreato-renal transplant, thrombosed splenic vein, hemangiomata, pancreatic pseudocysts, splenic artery aneurysm, cholesterol embolism, splenic granuloma, congenital diaphragmatic hernia, rib exostosis, pancreatitis, Gaucher's disease, Wilson's disease, pheochromocytoma, afibrinogenemia and ruptured ectopic pregnancy.

CONCLUSIONS

Emergency physicians should be attuned to the fact that rupture of the spleen can occur in the absence of major trauma or previously diagnosed splenic disease. The occurrence of such a rupture is likely to be the manifesting complaint of an underlying disease. Furthermore, colonoscopy should be more widely documented as a cause of splenic rupture.

Optimization of preload in severe sepsis and septic shock

In sepsis both under- and overresuscitation are associated with increased morbidity and mortality. Moreover, sepsis can be complicated by myocardial dysfunction, and only half of the critically ill patients exhibit preload responsiveness. It is of paramount importance to accurately, safely, and rapidly determine and optimize preload during resuscitation. Traditional methods of determining preload based on measurement of pressure in a heart chamber or volume of a heart chamber ("static" parameters) are inaccurate and should be abandoned in favor of determining preload responsiveness by using one of the "dynamic parameters" based on respiratory variation in the venous or arterial circulation or based on change in stroke volume in response to an endogenous or exogenous volume challenge. The recent development and validation of a number of noninvasive technologies now allow us to optimize preload in an accurate, safe, rapid and, cost-effective manner.

Essentials for selecting antimicrobial therapy for intra-abdominal infections

Intra-abdominal infection (IAI) is a complex disease entity in which different aspects must be balanced in order to select the proper antimicrobial regimen and determine duration of therapy. A current classification indicates different faces of peritonitis. Primary peritonitis implies an intact gastrointestinal tract without overt barrier disruption. Secondary peritonitis refers to localized or diffuse peritoneal inflammation and abscess formation due to disruption of the anatomical barrier. Tertiary peritonitis includes cases that cannot be solved by a single or even sequential surgical intervention, often in combination with sequential courses of antimicrobial therapy. The most frequently used classification distinguishes ‘uncomplicated’ and ‘complicated’ IAI. In uncomplicated IAI, the infectious process is contained within a single organ, without anatomical disruption. In complicated IAI, disease is extended, with either localized or generalized peritonitis. However, there exists more than a single dimension of complexity in IAI, including severity of disease expression through systemic inflammation. As the currently used classifications of IAI often incite confusion by mixing elements of anatomical barrier disruption, severity of disease expression and (the likelihood of) resistance involvement, we propose an alternative for the current widely accepted classification. We suggest abandoning the terms ‘uncomplicated’ and ‘complicated’ IAI, as they merely confuse the issue. Furthermore, the term ‘tertiary peritonitis’ should likewise be discarded, as this simply refers to treatment failure of secondary peritonitis resulting in a state of persistent infection and/or inflammation. Hence, anatomical disruption and disease severity should be separated into different phenotypes for the same disease in combination with either presence or absence of risk factors for involvement of pathogens that are not routinely covered in first-line antimicrobial regimens (Pseudomonas aeruginosa, enterococci, Candida species and resistant pathogens). Generally, these risk factors can be brought back to recent exposure to antimicrobial agents and substantial length of stay in healthcare settings (5–7 days). As such, we developed a grid based on the different components of the classification: (i) anatomical disruption; (ii) severity of disease expression; and (iii) either community-acquired/early-onset healthcare-associated origin or healthcare-associated origin and/or recent antimicrobial exposure. The grid allows physicians to define the index case of IAI in a more unequivocal way and to select the most convenient empirical antimicrobial regimens. The grid advises on the necessity of covering nosocomial Gram-negative bacteria (including P. aeruginosa), enterococci and yeasts. The basis of antimicrobial therapy for IAI is that both Gram-negative and anaerobic bacteria should always be covered.

In recent years, some newer agents such as doripenem, moxifloxacin and tigecycline have been added to the antimicrobial armamentarium for IAI. For patients in whom the source can be adequately controlled, antimicrobial therapy should be restricted to a short course (e.g. 3–7 days in peritonitis).

Pulse pressure variation and prediction of fluid responsiveness in patients ventilated with low tidal volumes

OBJECTIVE

To determine the utility of pulse pressure variation (ΔRESP PP) in predicting fluid responsiveness in patients ventilated with low tidal volumes (V T) and to investigate whether a lower ΔRESP PP cut-off value should be used when patients are ventilated with low tidal volumes.

METHOD

This cross-sectional observational study included 37 critically ill patients with acute circulatory failure who required fluid challenge. The patients were sedated and mechanically ventilated with a V T of 6-7 ml/kg ideal body weight, which was monitored with a pulmonary artery catheter and an arterial line. The mechanical ventilation and hemodynamic parameters, including ΔRESP PP, were measured before and after fluid challenge with 1,000 ml crystalloids or 500 ml colloids. Fluid responsiveness was defined as an increase in the cardiac index of at least 15%. ClinicalTrial.gov: NCT01569308.

RESULTS

A total of 17 patients were classified as responders. Analysis of the area under the ROC curve (AUC) showed that the optimal cut-off point for ΔRESP PP to predict fluid responsiveness was 10% (AUC = 0.74). Adjustment of the ΔRESP PP to account for driving pressure did not improve the accuracy (AUC = 0.76). A ΔRESP PP ≥ 10% was a better predictor of fluid responsiveness than central venous pressure (AUC = 0.57) or pulmonary wedge pressure (AUC = 051). Of the 37 patients, 25 were in septic shock. The AUC for ΔRESP PP ≥ 10% to predict responsiveness in patients with septic shock was 0.484 (sensitivity, 78%; specificity, 93%).

CONCLUSION

The parameter D RESP PP has limited value in predicting fluid responsiveness in patients who are ventilated with low tidal volumes, but a ΔRESP PP>10% is a significant improvement over static parameters. A ΔRESP PP ≥ 10% may be particularly useful for identifying responders in patients with septic shock.

Dynamic variables of fluid responsiveness during pneumoperitoneum and laparoscopic surgery

BACKGROUND

Few data exist on dynamic variables predicting fluid responsiveness during laparoscopic surgery. The aim of this study was to explore the effects of laparoscopy on four dynamic variables: respiratory variations in pulse pressure (ΔPP), stroke volume variation by Vigileo/FloTrac (SVV (Vigileo) ), pleth variability index (PVI) and respiratory variations in pulse oximetry plethysmography waveform amplitude (ΔPOP), and their relation to fluid challenges during laparoscopic surgery.

METHODS

ΔPP, SVV (Vigileo) , PVI and ΔPOP were studied in 20 adult patients before and during pneumoperitoneum (10-12 mmHg). During ongoing laparoscopic surgery, relations between the dynamic variables and changes in stroke volume oesophageal Doppler, (SV(OD) ) after fluid challenges (250 ml colloid) were evaluated.

RESULTS

Pneumoperitoneum changed the dynamic variables as follows {mean [95% confidence interval (CI)]}: ΔPP 0.5 (-1.3, 2.3)%, P = 0.53; SVV (Vigileo) 0.6 (-1.3, 2.5)%, P = 0.52; PVI 2.9 (0.4, 5.3)%, P = 0.025. For ΔPOP, median difference (95% CI) was 2.5 (-0.15, 6.7)%, P = 0.058. During laparoscopic surgery, areas under receiver operating characteristics curves (95% CI) were ΔPP 0.53 (0.31-0.75), SVV (Vigileo) 0.74 (0.51-0.90), PVI 0.61 (0.38-0.81), ΔPOP 0.63 (0.40-0.82). Correlation coefficients (P-values) between changes in dynamic variables and changes in SV(OD) were ΔPP r = -0.65, P = 0.009; SVV (Vigileo) r = -0.73, P = 0.002; PVI r = -0.22, P = 0.44; ΔPOP r = -0.32, P = 0.24.

CONCLUSION

ΔPP and SVV (Vigileo) did not change as pneumoperitoneum was established, whereas PVI increased and ΔPOP tended to increase. All four dynamic variables predicted fluid responsiveness relatively poor during ongoing laparoscopic surgery. ΔPP and SVV (Vigileo) tracked changes in stroke volume induced by fluid challenges during ongoing laparascopic surgery, whereas ΔPOP and PVI did not.

Comparison of superior vena cava and femoroiliac vein pressure according to intra-abdominal pressure

Background

Previous studies have shown a good agreement between central venous pressure (CVP) measurements from catheters placed in superior vena cava and catheters placed in the abdominal cava/common iliac vein. However, the influence of intra-abdominal pressure on such measurements remains unknown.

Methods

We conducted a prospective, observational study in a tertiary teaching hospital. We enrolled patients who had indwelling catheters in both superior vena cava (double lumen catheter) and femoroiliac veins (dialysis catheter) and into the bladder. Pressures were measured from all the sites, CVP, femoroiliac venous pressure (FIVP), and intra-abdominal pressure.

Results

A total of 30 patients were enrolled (age 62 ± 14 years; SAPS II 62 (52–76)). Fifty complete sets of measurements were performed. All of the studied patients were mechanically ventilated (PEP 3 cmH₂0 (2–5)). We observed that the concordance between CVP and FIVP decreased when intra-abdominal pressure increased. We identified 14 mmHg as the best intra-abdominal pressure cutoff, and we found that CVP and FIVP were significantly more in agreement below this threshold than above (94% versus 50%, P = 0.002).

Conclusions

We reported that intra-abdominal pressure affected agreement between CVP measurements from catheter placed in superior vena cava and catheters placed in the femoroiliac vein. Agreement was excellent when intra-abdominal pressure was below 14 mmHg.

Goal-directed fluid therapy using stroke volume variation does not result in pulmonary fluid overload in thoracic surgery requiring one-lung ventilation

Background. Goal-directed fluid therapy (GDT) guided by functional parameters of preload, such as stroke volume variation (SVV), seems to optimize hemodynamics and possibly improves clinical outcome. However, this strategy is believed to be rather fluid aggressive, and, furthermore, during surgery requiring thoracotomy, the ability of SVV to predict volume responsiveness has raised some controversy. So far it is not known whether GDT is associated with pulmonary fluid overload and a deleterious reduction in pulmonary function in thoracic surgery requiring one-lung-ventilation (OLV). Therefore, we assessed the perioperative course of extravascular lung water index (EVLWI) and p_aO₂/F_iO₂-ratio during and after thoracic surgery requiring lateral thoracotomy and OLV to evaluate the hypothesis that fluid therapy guided by SVV results in pulmonary fluid overload. Methods. A total of 27 patients (group T) were enrolled in this prospective study with 11 patients undergoing lung surgery (group L) and 16 patients undergoing esophagectomy (group E). Goal-directed fluid management was guided by SVV (SVV < 10%). Measurements were performed directly after induction of anesthesia (baseline—BL), 15 minutes after implementation OLV (OLVimpl15), and 15 minutes after termination of OLV (OLVterm15). In addition, postoperative measurements were performed at 6 (6postop), 12 (12postop), and 24 (24postop) hours after surgery. EVLWI was measured at all predefined steps. The p_aO₂/F_iO₂-ratio was determined at each point during mechanical ventilation (group L: BL-OLVterm15; group E: BL-24postop). Results. In all patients (group T), there was no significant change (P > 0.05) in EVLWI during the observation period (BL: 7.8 ± 2.5, 24postop: 8.1 ± 2.4 mL/kg). A subgroup analysis for group L and group E also did not reveal significant changes of EVLWI. The p_aO₂/F_iO₂-ratio decreased significantly during the observation period (group L: BL: 462 ± 140, OLVterm15: 338 ± 112 mmHg; group E: BL: 389 ± 101, 24postop: 303 ± 74 mmHg) but remained >300 mmHg except during OLV. Conclusions. SVV-guided fluid management in thoracic surgery requiring lateral thoracotomy and one-lung ventilation does not result in pulmonary fluid overload. Although oxygenation was reduced, pulmonary function remained within a clinically acceptable range.

Respiratory variations of R-wave amplitude in lead II are correlated with stroke volume variations evaluated by transesophageal Doppler echocardiography

OBJECTIVE

The authors hypothesized that variations in electrocardiographically derived R-wave amplitude might be correlated with mechanical ventilation-induced variations in stroke volume as determined by transesophageal echocardiography.

DESIGN

Observational prospective study.

SETTING

Single university hospital.

PARTICIPANTS

Thirty-four patients undergoing coronary artery bypass surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Respiratory R-wave variations in lead II (ΔRII) were correlated with aortic velocity time integral variations (r = 0.82, p < 0.0001). Respiratory R-wave variations in leads III and aVF and pulse pressure variation also were correlated with aortic velocity time integral variations (r = 0.49, p = 0.015; r = 0.61, p = 0.0016; and r = 0.72, p < 0.0001, respectively). R-wave respiratory variations in lead V(5) were not correlated with aortic velocity time integral variations. ΔRII was correlated with pulse pressure variation (r = 0.71, p < 0.0001). A ΔRII cutoff value of 15% accurately predicted stroke volume variations >15%, with a specificity of 92%, a sensitivity of 86%, a positive likelihood ratio of 11.1, a negative likelihood ratio of 0.15, a positive predictive value of 95%, and a negative predictive value of 80%.

CONCLUSIONS

ΔRII is correlated with stroke volume variations as determined by transesophageal echocardiography in mechanically ventilated patients and can identify the stroke volume variation cutoff of 15%, previously determined to be the cutoff for volume responsiveness.

Hemodynamic consequences of auto-PEEP

Auto-positive end-expiratory pressure (PEEP) is a common but frequently unrecognized problem in critically ill patients. It has important physiologic consequences and can cause shock and cardiac arrest. Treatment consists of relieving expiratory airflow obstruction and reducing minute ventilation delivered by positive pressure ventilation. Sedation and fluid management are important adjunctive therapies. This analytic review discusses the prevalence, pathophysiology, and hemodynamic consequences of auto-PEEP and an approach to its treatment.

Spontaneous rupture of the spleen - a rare case

The study presented two cases of spontaneous rupture of the spleen. Both patients were treated at the Department of General, Oncological, and Endocrinological Surgery. The first patient underwent splenectomy. The postoperative course was uneventful. The second patient was subject to pharmacological treatment because of non-acceptance to surgical intervention. The patient died during the following hospitalization. Both patients received oral anticoagulants, due to atrial fibrillation and an implanted heart valve. History of previous trauma was absent. The study presented a detailed description of the clinical course of splenic rupture.

Pyrosequencing reveals the complex polymicrobial nature of invasive pyogenic infections: microbial constituents of empyema, liver abscess, and intracerebral abscess

The polymicrobial nature of invasive pyogenic infections may be underestimated by routine culture practices, due to the fastidious nature of many organisms and the loss of viability during transport or from prior antibacterials. Pyrosequencing was performed on brain and liver abscesses and pleural fluid and compared to routine culture data. Forty-seven invasive pyogenic infection samples from 44 patients [6 intracerebral abscess (ICA), 21 pyogenic liver abscess (PLA), and 18 pleural fluid (PF) samples] were assayed. Pyrosequencing identified an etiologic microorganism in 100 % of samples versus 45 % by culture, p <0.01. Pyrosequencing was also more likely than traditional cultures to classify infections as polymicrobial, 91 % versus 17 %, p <0.001. The median number of genera identified by pyrosequencing compared to culture was 1 [interquartile range (IQR) 1-3] versus 0 (IQR 0-1) for ICA, 7 (IQR 1-15) versus 1 (IQR 0-1) for PLA, and 15 (IQR 9-19) versus 0 (IQR 0-1) for PF. Where organisms were cultured, they typically represented the numerically dominant species identified by pyrosequencing. Complex microbial communities are involved in invasive pyogenic infection of the lung, liver, and brain. Defining the polymicrobial nature of invasive pyogenic infections is the first step towards appreciating the clinical and diagnostic implications of these complex communities.

Hypoperfusion, shock states, and abdominal compartment syndrome (ACS)

Cardiovascular dysfunction and failure are commonly encountered in patients with intra-abdominal hypertension or abdominal compartment syndrome. Accurate assessment and optimization of preload, afterload, and contractility are essential to restoring end-organ perfusion and maximizing patient survival. Application of a goal-directed resuscitation strategy, including abdominal decompression, when indicated, improves cardiac function, reverses end-organ failure, and minimizes intra-abdominal hypertension-related patient morbidity and mortality.

Non-invasive assessment of fluid responsiveness by changes in partial end-tidal CO2 pressure during a passive leg-raising maneuver

Background

The passive leg-raising (PLR) maneuver provides a dynamic assessment of fluid responsiveness inducing a reversible increase in cardiac preload. Since its effects are sudden and transitory, a continuous cardiac output (CO) monitoring is required to appropriately assess the hemodynamic response of PLR. On the other hand, changes in partial end-tidal CO₂ pressure (PETCO₂) have been demonstrated to be tightly correlated with changes in CO during constant ventilation and stable tissue CO₂ production (VCO₂). In this study we tested the hypothesis that, assuming a constant VCO₂ and under fixed ventilation, PETCO₂ can track changes in CO induced by PLR and can be used to predict fluid responsiveness.

Methods

Thirty-seven mechanically ventilated patients with acute circulatory failure were monitored with the CardioQ-ODM esophageal Doppler. A 2-minutes PLR maneuver was performed. Fluid responsiveness was defined according to CO increase (responders ≥ 15%) after volume expansion.

Results

PLR-induced increases in CO and PETCO₂ were strongly correlated (R² = 0.79; P < 0.0001). The areas under the receiver-operating characteristics (ROC) curve for a PLR-induced increase in CO and PETCO₂ (0.97 ± 0.03 SE; CI 95%: 0.85 to 0.99 and 0.94 ± 0.04 SE; CI 95%: 0.82 to 0.99; respectively) were not significantly different. An increase ≥ 5% in PETCO₂ or ≥ 12% in CO during PLR predicted fluid responsiveness with a sensitivity of 90.5% (95% CI: 69.9 to 98.8%) and 95.2% (95% CI: 76.2 to 99.9%), respectively, and a specificity of 93.7% (95% CI: 69.8 to 99.8%).

Conclusion

Induced changes in PETCO₂ during a PLR maneuver could be used to track changes in CO for prediction of fluid responsiveness in mechanically ventilated patients with acute circulatory failure, under fixed minute ventilation and assuming a constant tissue CO₂ production.

Evaluation of fluid responsiveness: is photoplethysmography a noninvasive alternative?

Background. Goal-directed fluid therapy reduces morbidity and mortality in various clinical settings. Respiratory variations in photoplethysmography are proposed as a noninvasive alternative to predict fluid responsiveness during mechanical ventilation. This paper aims to critically evaluate current data on the ability of photoplethysmography to predict fluid responsiveness. Method. Primary searches were performed in PubMed, Medline, and Embase on November 10, 2011. Results. 14 papers evaluating photoplethysmography and fluid responsiveness were found. Nine studies calculated areas under the receiver operating characteristic curves for ΔPOP (>0.85 in four, 0.75–0.85 in one, and <0.75 in four studies) and seven for PVI (values ranging from 0.54 to 0.98). Correlations between ΔPOP/PVI and ΔPP/other dynamic variables vary substantially. Conclusion. Although photoplethysmography is a promising technique, predictive values and correlations with other hemodynamic variables indicating fluid responsiveness vary substantially. Presently, it is not documented that photoplethysmography is adequately valid and reliable to be included in clinical practice for evaluation of fluid responsiveness.

Appreciating the strengths and weaknesses of transthoracic echocardiography in hemodynamic assessments

Transthoracic echocardiography (TTE) is becoming the choice of hemodynamic assessment tool in many intensive care units. With an ever increasing number of training programs available worldwide, learning the skills to perform TTE is no longer a limiting factor. Instead, the future emphasis will be shifted to teach the users how to recognize measurement errors and artefacts (internal validity), to realize the limitations of TTE in various applications, and finally how to apply the information to the patient in question (external validity). This paper aims to achieve these objectives in a common area of TTE application-hemodynamic assessments. We explore the strengths and weaknesses of TTE in such assessments in this paper. Various methods of hemodynamic assessments, such as cardiac output measurements, estimation of preload, and assessment of fluid responsiveness, will be discussed.

Advanced hemodynamic monitoring: principles and practice in neurocritical care

Advanced hemodynamic monitoring is necessary for many patients with acute brain and/or spinal cord injury. Optimizing cerebral and systemic physiology requires multi-organ system function monitoring. Hemodynamic manipulations are cardinal among interventions to regulate cerebral perfusion pressure and cerebral blood flow. The pulmonary artery catheter is not any more the sole tool available; less invasive and potentially more accurate methodologies have been developed and employed in the operating room and among diverse critically ill populations. These include transpulmonary thermodilution, arterial pressure pulse contour, and waveform analysis and bedside critical care ultrasound. A thorough understanding of hemodynamics and of the available monitoring modalities is an essential skill for the neurointensivist.

Hemodynamic changes during a deep inspiration maneuver predict fluid responsiveness in spontaneously breathing patients

Objective. We hypothesized that the hemodynamic response to a deep inspiration maneuver (DIM) indicates fluid responsiveness in spontaneously breathing (SB) patients. Design. Prospective study. Setting. ICU of a general hospital. Patients. Consecutive nonintubated patients without mechanical ventilation, considered for volume expansion (VE). Intervention. We assessed hemodynamic status at baseline and after VE. Measurements and Main Results. We measured radial pulse pressure (PP) using an arterial catheter and peak velocity of femoral artery flow (VF) using continuous Doppler. Changes in PP and VF induced by a DIM (ΔPPdim and ΔVFdim) were calculated in 23 patients. ΔPPdim and ΔVFdim ≥12% predicted responders to VE with sensitivity of 90% and specificity of 100%. Conclusions. In a restricted population of SB patients with severe sepsis or acute pancreatitis, ΔPPdim and ΔVFdim are accurate indices for predicting fluid responsiveness. These results should be confirmed in a larger population before validating their use in current practice.

Year in review 2010: Critical Care--Cardiology

We review key research papers in cardiology and intensive care published during 2010 in Critical Care and quote related studies published in other journals if appropriate. Papers were grouped into the following categories: cardiovascular therapies, biomarkers, hemodynamic monitoring, cardiovascular diseases, and microcirculation.

Photoplethysmographic and pulse pressure variations during abdominal surgery

BACKGROUND

Respiratory variations in pulse pressure (ΔPP) predict fluid responsiveness during mechanical ventilation. Variations in pulse oximetry plethysmography amplitude (ΔPOP) are proposed as a non-invasive alternative. Large variations in ΔPOP and poor agreement between ΔPP and ΔPOP are found in intensive care unit patients. General anaesthesia is suggested to reduce variability of ΔPOP and improve agreement between the variables. We evaluated the variability of the agreement between and the diagnostic values of ΔPP and ΔPOP during ongoing open abdominal surgery. The variability of diagnostic methods in specific clinical conditions is important, as this reflects the stability over time during which clinical decisions are made.

METHODS

Observational study during open abdominal surgery in general anaesthesia. ΔPP and ΔPOP were calculated semi-automatically from recording periods of approximately 5 min both before and after fluid challenges. Fluid responsiveness was evaluated by changes in stroke volume (oesophageal Doppler) after 250 ml colloid.

RESULTS

Thirty-four fluid challenges were performed in 25 patients. Variance both within registration periods and between patients were significantly larger for ΔPOP than for ΔPP (54.1% vs. 22.1% and 69.6% vs. 22.6%, respectively, both P < 0.001). Limits of agreement with a regression-based correction were ± 13.9%. Areas under receiver operating characteristics curves for fluid responsiveness were 0.67 for ΔPP and 0.72 for ΔPOP.

CONCLUSIONS

Analysis of raw signals during open abdominal surgery documents that the variance of ΔPOP is larger than of ΔPP, with wide limits of agreement between ΔPP and ΔPOP. The diagnostic values of ΔPP and ΔPOP are relatively poor.