Samir G. Sakka

Assessment of cardiac preload and extravascular lung water by single transpulmonary thermodilution

Objective: Transpulmonary double-indicator dilution is a useful monitoring technique for measurement of intrathoracic blood volume (ITBV) and extravascular lung water (EVLW). In this study, we compared a simpler approach using single arterial thermodilution derived measurements of ITBV and EVLW with the double-indicator dilution technique.¶Design: Prospective observational clinical study.¶Setting: Surgical intensive care units of two university hospitals.¶Patients and methods: Global end-diastolic volume (GEDV) derived from single thermodilution was used for calculation of ITBV. Structural regression analysis of the first two thermo-dye dilution measurements in a derivation population of 57 critically ill patients (38 male, 19 female, 18–79 years, 56 ± 15 years) revealed ITBV = (1.25 · GEDV)–28.4 (ml). This equation was then applied to all first measurements in a validation population of 209 critically ill patients (139 male, 70 female, 10–88 years, mean 53 ± 19 years), and single-thermodilution ITBV (ITBVST) and EVLW (EVLWST) was calculated and compared to thermo-dye dilution derived values (ITBVTD, EVLWTD). For inter-individual comparison, absolute values for ITBV and EVLW were normalised as indexed by body surface area (ITBVI) and body weight (EVLWI), respectively.¶Measurements and results: Linear regression analysis yielded a correlation of ITBVIST = (1.05 · ITBVITD)–58.0 (ml/m2), r = 0.97, P < 0.0001. Bias between ITBVITD and ITBVIST was 7.6 (ml/m2) with a standard deviation of 57.4 (ml/m2). Single-thermodilution EVLWI (EVLWIST) was calculated using ITBVIST and revealed the correlation EVLWIST = (0.83 · EVLWITD) + 1.6 (ml/kg), r = 0.96, P < 0.0001. Bias between EVLWITD and EVLWIST was –0.2 (ml/kg) with a standard deviation of 1.4 (ml/kg). In detail, EVLWIST systematically overestimated EVLWITD at low-normal values for EVLWI and underestimated EVLWI at higher values (above 12 ml/kg).¶Conclusion: Determinations of ITBV and EVLW by single thermodilution agreed closely with the corresponding values from the double-indicator technique. Since transpulmonary single thermodilution is simple to apply, less invasive and cheaper, all these features make it a promising technique for the bedside. Nevertheless, further validation studies are needed in the future.

Comparison of pulmonary artery and arterial thermodilution cardiac output in critically ill patients.

Objective: We studied the agreement between cardiac output measurements via pulmonary artery thermodilution [CO(PA)], regarded as the current clinical gold standard, and aortic transpulmonary thermodilution [CO(AORTA)]. Design: Prospective clinical study. Setting: Surgical intensive care unit of a university hospital. Patients: 37 patients with sepsis or septic shock (n = 34) and subarachnoid haemorrhage (n = 3). Measurements and results: We analysed 449 simultaneous cardiac output measurements. All patients were deeply sedated and mechanically ventilated in a pressure controlled mode. Each patient received a 7.5-F five-lumen pulmonary artery catheter and a 4-F aortic catheter with an integrated thermistor. The thermistors of the two different catheters were connected to one computer system (COLD-Z021, Pulsion Medical Systems, Munich, Germany). Linear regression analysis revealed: CO(AORTA) = 0.96 · CO(PA) + 1.02 (l/min) (r = 0.97, p < 0.0001). CO(AORTA) was consistently higher than CO(PA) with a bias of 0.68 (l/min) and a standard deviation of 0.62 (l/min). Conclusion: Cardiac output derived from aortic transpulmonary thermodilution is suitable for measurement in the intensive care unit. Measurements of CO(AORTA) are consistent with, but slightly higher than, those obtained from pulmonary artery thermodilution.

Diagnosis of Bacteremia in Whole-Blood Samples by Use of a Commercial Universal 16S rRNA Gene-Based PCR and Sequence Analysis

ABSTRACT In a prospective, multicenter study of 342 blood samples from 187 patients with systemic inflammatory response syndrome, sepsis, or neutropenic fever, a new commercial PCR test (SepsiTest; Molzym) was evaluated for rapid diagnosis of bacteremia. The test comprises a universal PCR from the 16S rRNA gene, with subsequent identification of bacteria from positive samples by sequence analysis of amplicons. Compared to blood culture (BC), the diagnostic sensitivity and specificity of the PCR were 87.0 and 85.8%, respectively. Considering the 34 BC-positive patients, 28 were also PCR positive in at least one of the samples, resulting in a patient-related sensitivity of 82.4%. The concordance of PCR and BC for both positive and negative samples was (47 + 247)/342, i.e., 86.0%. In total, 31 patients were PCR/sequencing positive and BC negative, in whom the PCR result was judged as possible or probable to true bacteremia in 25. In conclusion, the PCR approach facilitates the detection of bacteremia in blood samples within a few hours. Despite the indispensability of BC diagnostics, the rapid detection of bacteria by SepsiTest appears to be a valuable tool, allowing earlier pathogen-adapted antimicrobial therapy in critically ill patients.

Influence of systolic-pressure-variation-guided intraoperative fluid management on organ function and oxygen transport

BACKGROUND Dynamic variables, for example, systolic pressure variation (SPV), are superior to filling pressures for assessing fluid responsiveness. We analysed the effects of SPV-guided intraoperative fluid management on organ function and perfusion when compared with routine care. METHODS Eighty patients (44 female and 36 male) undergoing elective major abdominal surgery were randomly assigned to a control group [n=40, mean age 66 (sd 10), range 40-84 yr] or SPV group [n=40, age 61 (16), range 26-100 yr] in which intraoperative fluid management was guided by SPV (trigger: SPV>10%). Central venous O2 saturation (ScvO2), lactate and bilirubin, creatinine, indocyanine green plasma disappearance rate (ICG-PDR), and gastric mucosal CO(2) tension were measured after induction of anaesthesia, after 3, 6, 12, and 24 h. RESULTS Patient characteristics, duration of surgery [5.8 (2.5) vs 5.4 (2.5) h], and infusion volumes (median 4865 vs 4330 ml) were comparable between the groups. At 3 and 6 h, SPV (P=0.04, P=0.01) and Deltadown (P=0.005, P=0.01) were significantly higher in the control group. Oxygen transport and organ function were comparable: baseline and 24 h values for ICG-PDR: 28.5 (7.9) and 22.7 (7.8) vs 23.9 (6.9) and 26.1 (5.9)% min(-1), 77.7 (6.6) and 72.6 (5.5) vs 79.3 (7.1) and 72.8 (6.7)% for ScvO2 and 1.0 (0.4) and 1.2 (0.6) vs 0.9 (0.2) and 1.3 (0.5) mmol litre(-1) for lactate. Length of mechanical ventilation, ICU stay, and mortality were comparable. CONCLUSIONS In comparison with routine care, intraoperative SPV-guided treatment was associated with slightly increased fluid adminstration whereas organ perfusion and function was similar.

Perioperative goal-directed hemodynamic therapy based on radial arterial pulse pressure variation and continuous cardiac index trending reduces postoperative complications after major abdominal surgery: a multi-center, prospective, randomized study.

IntroductionSeveral single-center studies and meta-analyses have shown that perioperative goal-directed therapy may significantly improve outcomes in general surgical patients. We hypothesized that using a treatment algorithm based on pulse pressure variation, cardiac index trending by radial artery pulse contour analysis, and mean arterial pressure in a study group (SG), would result in reduced complications, reduced length of hospital stay and quicker return of bowel movement postoperatively in abdominal surgical patients, when compared to a control group (CG).Methods160 patients undergoing elective major abdominal surgery were randomized to the SG (79 patients) or to the CG (81 patients). In the SG hemodynamic therapy was guided by pulse pressure variation, cardiac index trending and mean arterial pressure. In the CG hemodynamic therapy was performed at the discretion of the treating anesthesiologist. Outcome data were recorded up to 28 days postoperatively.ResultsThe total number of complications was significantly lower in the SG (72 vs. 52 complications, p = 0.038). In particular, infection complications were significantly reduced (SG: 13 vs. CG: 26 complications, p = 0.023). There were no significant differences between the two groups for return of bowel movement (SG: 3 vs. CG: 2 days postoperatively, p = 0.316), duration of post anesthesia care unit stay (SG: 180 vs. CG: 180 minutes, p = 0.516) or length of hospital stay (SG: 11 vs. CG: 10 days, p = 0.929).ConclusionsThis multi-center study demonstrates that hemodynamic goal-directed therapy using pulse pressure variation, cardiac index trending and mean arterial pressure as the key parameters leads to a decrease in postoperative complications in patients undergoing major abdominal surgery.Trial registrationClinicalTrial.gov, NCT01401283.

Detection of Candidatus Neoehrlichia mikurensis in two patients with severe febrile illnesses: evidence for a European sequence variant

ABSTRACT Recently, a new genus of Anaplasmataceae termed “Candidatus Neoehrlichia” was discovered in ticks and rodents. Here, we report on two patients who suffered from febrile bacteremia due to “Candidatus Neoehrlichia mikurensis” associated with thrombotic or hemorrhagic events. 16S rRNA and groEL gene sequencing provided evidence of three groups of sequence variants.

Epidemiology and risk factors of sepsis after multiple trauma: An analysis of 29,829 patients from the Trauma Registry of the German Society for Trauma Surgery*

Objectives:The objectives of this study were 1) to assess potential changes in the incidence and outcome of sepsis after multiple trauma in Germany between 1993 and 2008 and 2) to evaluate independent risk factors for posttraumatic sepsis. Design:Retrospective analysis of a nationwide, population-based prospective database, the Trauma Registry of the German Society for Trauma Surgery. Setting:A total of 166 voluntarily participating trauma centers (levels I–III). Patients:Patients registered in the Trauma Registry of the German Society for Trauma Surgery between 1993 and 2008 with complete data sets who presented with a relevant trauma load (Injury Severity Score of ≥9) and were admitted to an intensive care unit (n = 29,829). Interventions:None. Measurements and Main Results:Over the 16-yr study period, 10.2% (3,042 of 29,829) of multiply injured patients developed sepsis during their hospital course. Annual data were summarized into four subperiods: 1993–1996, 1997–2000, 2001–2004, and 2005–2008. The incidences of sepsis for the four subperiods were 14.8%, 12.5%, 9.4%, and 9.7% (p < .0001), respectively. In-hospital mortality for all trauma patients decreased for the respective subperiods (16.9%, 16.0%, 13.7%, and 11.9%; p < .0001). For the subgroup of patients with sepsis, the mortality rates were 16.2%, 21.5%, 22.0%, and 18.2% (p = .054), respectively. The following independent risk factors for posttraumatic sepsis were calculated from a multivariate logistic regression analysis: male gender, age, preexisting medical condition, Glasgow Coma Scale score of ≤8 at scene, Injury Severity Score, Abbreviated Injury ScaleTHORAX score of ≥3, number of injuries, number of red blood cell units transfused, number of operative procedures, and laparotomy. Conclusions:The incidence of sepsis decreased significantly over the study period; however, in this decade the incidence remained unchanged. Although overall mortality from multiple trauma has declined significantly since 1993, there has been no significant decrease of mortality in the subgroup of septic trauma patients. Thus, sepsis has remained a challenging complication after trauma during the past 2 decades. Recognition of the identified risk factors may guide early diagnostic workup and help to reduce septic complications after multiple trauma.

Activity and DNA contamination of commercial polymerase chain reaction reagents for the universal 16S rDNA real-time polymerase chain reaction detection of bacterial pathogens in blood

Universal 16S rRNA gene polymerase chain reaction (PCR) is a promising means of detecting bacteremia. Among other factors, the PCR reagents play a prominent role for obtaining a high sensitivity of detection. The reagents are ideally optimized with respect to the amplifying activity and absence of contaminating DNA. In this study, it was shown in a universal 16S rDNA real-time PCR assay that commercial PCR reagents can vary greatly among each other in these characters. Only 1 of the 5 reagents tested met the criteria of sensitive detection of pathogen DNA with a minimum of false-positive results. The reagent was validated by the detection of pathogens at low titers using bacterial DNA extracted from blood that was spiked with various Gram-positive and Gram-negative bacteria.

Clinical review: influence of vasoactive and other therapies on intestinal and hepatic circulations in patients with septic shock.

The organs of the hepatosplanchnic system are considered to play a key role in the development of multiorgan failure during septic shock. Impaired oxygenation of the intestinal mucosa can lead to disruption of the intestinal barrier, which may promote a vicious cycle of inflammatory response, increased oxygen demand and inadequate oxygen supply. Standard septic shock therapy includes supportive treatment such as fluid resuscitation, administration of vasopressors (adrenergic and nonadrenergic drugs), and respiratory and renal support. These therapies may have beneficial or detrimental effects not only on systemic haemodynamics but also on splanchnic haemodynamics, at both the macrocirculatory and microcirculatory levels. This clinical review focuses on the splanchnic haemodynamic and metabolic effects of standard therapies used in patients with septic shock, as well as on the recently described nonconventional therapies such as vasopressin, prostacyclin and N-acetyl cysteine.

Is the placement of a pulmonary artery catheter still justified solely for the measurement of cardiac output

OBJECTIVE The authors compared four clinical techniques of measuring cardiac output (CO) in critically ill patients: pulmonary artery thermodilution (CO[PA]), transpulmonary aortic thermodilution (CO[AORTA]), Fick principle-derived (CO[FICK]), and continuous pulmonary artery (CCO) measurements. DESIGN Prospective clinical study. SETTING Surgical intensive care unit of a university hospital. PARTICIPANTS Twelve adult patients suffering from sepsis or septic shock. INTERVENTIONS All patients were deeply sedated and mechanically ventilated in a pressure-controlled mode. Each patient received a 7.5F five-lumen pulmonary artery catheter for the continuous measurement of cardiac output and a 4F aortic catheter with an integrated thermistor. The thermistors of the two different catheters were connected to one computer system (COLD-Z021, Pulsion Medical Systems, Munich, Germany). Whole-body oxygen consumption was measured by indirect calorimetry using a metabolic cart (Deltatrac, Datex-Engstroem, Helsinki, Finland) over a 5-minute period, at the end of which arterial and mixed venous blood gases were taken and measured by co-oximetry. During each measuring period, three bolus CO measurements were performed. A total number of 51 CO measurements was analyzed. RESULTS Linear regression analysis revealed the highest correlation between CO(AORTA) and CO(PA) (r = 0.98), whereas agreement between these two techniques and CCO was lower (r = 0.92 and r = 0.93). All three techniques correlated comparably with CO(FICK) (r = 0.85, r = 0.83, and r = 0.83). CONCLUSION The correlations among the four CO techniques were high and similar, with CO(PA) and CO(AORTA) techniques showing the highest agreement. Because CO with similar accuracy can be obtained from transpulmonary aortic thermodilution in a less-invasive manner, it appears that the placement of a pulmonary artery catheter solely for the measurement of CO is no longer justified, unless continuous CO measurements are needed.