Practice parameters for hemodynamic support of sepsis in adult patients: 2004 update

Plasma-induced endothelial oxidative stress is related to the severity of septic shock*

OBJECTIVE

To estimate the capacity of plasma from septic shock patients to induce in vitro reactive oxygen species (ROS) production by endothelial cells and to analyze whether ROS production is related to the severity of the septic shock.

DESIGN

Prospective, observational study.

SETTING

Medical intensive care unit in a university hospital.

PATIENTS

Twenty-one patients with septic shock.

INTERVENTIONS

The in vitro capacity of plasma from septic shock patients to induce ROS production by naive human umbilical vein endothelial cells (HUVEC) was quantified by using a fluorescent probe (2',7'-dichlorodihydrofluorescein diacetate).

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected on day 1, day 3, and day 5 from 21 consecutive septic shock adult patients and from ten healthy volunteers. Patients mean age was 58 yrs old, mean Sequential Organ Failure Assessment (SOFA) score at admission was 12, mean severity illness assessed by Simplified Acute Physiology Score (SAPS) II was 53, and the mortality rate was 47%. In addition to assessment of in vitro ROS generation by HUVEC, oxidative stress in blood was evaluated by measuring lipid peroxidation products and enzymatic and nonenzymatic antioxidants. Septic shock was associated with oxidative stress and an imbalance in antioxidant status. As compared with controls, plasma-induced ROS production by naive HUVEC was significantly higher in septic shock. Moreover ROS production was significantly correlated with SAPS II (p = .028) and SOFA values (p = .0012) and was higher in nonsurvivors than in survivors. In contrast, no correlation was found between the severity of the septic shock and any of the levels of lipid peroxidation products or enzymatic and nonenzymatic antioxidants.

CONCLUSION

Plasma from septic shock patients induces ROS formation by naive HUVEC, and the extent of ROS formation correlates with mortality and with criteria of the severity of septic shock as SOFA score and SAPS II.

Cardiac filling pressures are not appropriate to predict hemodynamic response to volume challenge

OBJECTIVE

Values of central venous pressure of 8-12 mm Hg and of pulmonary artery occlusion pressure of 12-15 mm Hg have been proposed as volume resuscitation targets in recent international guidelines on management of severe sepsis. By analyzing a large number of volume challenges, our aim was to test the significance of the recommended target values in terms of prediction of volume responsiveness.

DESIGN

Retrospective study.

SETTING

A 24-bed medical intensive care unit.

PATIENTS

All consecutive septic patients monitored with a pulmonary artery catheter who underwent a volume challenge between 2001 and 2004.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

A total of 150 volume challenges in 96 patients were reviewed. In 65 instances, the volume challenge resulted in an increase in cardiac index of > or =15% (responders). The pre-infusion central venous pressure was similar in responders and nonresponders (8 +/- 4 vs. 9 +/- 4 mm Hg). The pre-infusion pulmonary artery occlusion pressure was slightly lower in responders (10 +/- 4 vs. 11 +/- 4 mm Hg, p < .05). However, the significance of pulmonary artery occlusion pressure to predict fluid responsiveness was poor and similar to that of central venous pressure, as indicated by low values of areas under the receiver operating characteristic curves (0.58 and 0.63, respectively). A central venous pressure of <8 mm Hg and a pulmonary artery occlusion pressure of <12 mm Hg predicted volume responsiveness with a positive predictive value of only 47% and 54%, respectively. With the knowledge of a low stroke volume index (<30 mL.m), their positive predictive values were still unsatisfactory: 61% and 69%, respectively. When the combination of central venous pressure and pulmonary artery occlusion pressure was considered instead of either pressure alone, the degree of prediction of volume responsiveness was not improved.

CONCLUSION

Our study demonstrates that cardiac filling pressures are poor predictors of fluid responsiveness in septic patients. Therefore, their use as targets for volume resuscitation must be discouraged, at least after the early phase of sepsis has concluded.

Dobutamine reverses the vasopressin-associated impairment in cardiac index and systemic oxygen supply in ovine endotoxemia

Introduction

Arginine vasopressin (AVP) is increasingly used to treat sepsis-related vasodilation and to decrease catecholamine requirements. However, AVP infusion may be associated with a marked decrease in systemic blood flow and oxygen transport. The purpose of the present study was to evaluate whether dobutamine may be titrated to reverse the AVP-related decrease in cardiac index (CI) and systemic oxygen delivery index (DO₂I) in an established model of ovine endotoxemia.

Methods

Twenty-four adult ewes were chronically instrumented to determine cardiopulmonary hemodynamics and global oxygen transport. All ewes received a continuous endotoxin infusion that contributed to a hypotensive-hyperdynamic circulation and death of five sheep. After 16 hours of endotoxemia, the surviving ewes (n = 19; weight 35.6 ± 1.5 kg (mean ± SEM)) were randomized to receive either AVP (0.04 Umin^-1) and dobutamine (n = 8) or the vehicle (normal saline; n = 6) and compared with a third group treated with AVP infusion alone (n = 5). Dobutamine infusion was started at an initial rate of 2 μg kg^-1min^-1 and was increased to 5 and 10 μg kg^-1 min^-1 after 30 and 60 minutes, respectively.

Results

AVP infusion increased mean arterial pressure (MAP) and systemic vascular resistance index at the expense of a markedly decreased CI (4.1 ± 0.5 versus 8.2 ± 0.3 l min^-1 m^-2), DO₂I (577 ± 68 versus 1,150 ± 50 ml min^-1 m^-2) and mixed-venous oxygen saturation (S_vO₂; 54.5 ± 1.8% versus 69.4 ± 1.0%; all p < 0.001 versus control). Dobutamine dose-dependently reversed the decrease in CI (8.8 ± 0.7 l min^-1 m^-2 versus 4.4 ± 0.5 l min^-1 m^-2), DO₂I (1323 ± 102 versus 633 ± 61 ml min^-1 m^-2) and S_vO₂ (72.2 ± 1.7% versus 56.5 ± 2.0%, all p < 0.001 at dobutamine 10 μg kg^-1 min^-1 versus AVP group) and further increased MAP.

Conclusion

This study provides evidence that dobutamine is a useful agent for reversing the AVP-associated impairment in systemic blood flow and global oxygen transport.

Vasopressor Therapy Using Vasopressin Prior to Crystalloid Resuscitation in Irreversible Hemorrhagic Shock under Isoflurane Anesthesia in Dogs

In the present study, we tested the hypothesis that vasopressin administration prior to crystalloid resuscitation can be used to improve hemodynamic and oxygen delivery functions. Hemorrhagic shock was experimentally induced by maintaining mean arterial pressure at 60 mmHg for 30 min in sixteen healthy dogs weighing from 8 to 10.6 kg. Vasopressin was administered and then volume resuscitation was performed for the 6 dogs of V-C group, while vasopressin was administered at the end of volume resuscitation in the 5 dogs of C-V group. The control group (n=5) was administered 0.4 IU/kg of vasopressin after induction of shock without fluid resuscitation. In all groups, hemodynamic parameters were measured pre- and post-hemorrhage and for 60 min after fluid resuscitation. The dogs in V-C group had substantially increased systolic arterial pressure (SAP) for 60 min and improved pulmonary capillary wedge pressure (PCWP), cardiac output (CO), oxygen delivery, and oxygen consumption indexes compared with C-V and control groups. Diastolic pressure and systemic vascular resistance was significantly lower in the V-C group than those in the C-V and control groups (P<0.05). In the V-C group, there was effective and rapid restoration of the SAP, CO, PCWP, and oxygen delivery parameters after treatment. This study indicates that vasopressin administration before crystalloid resuscitation is a more efficient way of improving hemodynamic and oxygen delivery functions in hemorrhagic shock in dogs.

Hemodynamic goals in randomized clinical trials in patients with sepsis: a systematic review of the literature

INTRODUCTION

Patients with sepsis suffer high morbidity and mortality. We sought to conduct a systematic review of the literature to evaluate the association between hemodynamic goals of therapy and patient outcomes.

METHODS

We conducted a comprehensive search of the literature to systematically review hemodynamic goals used in clinical trials in patients with sepsis. We searched the literature using the Pubmed (1965-June 2006), Embase (1974-June 2006), CINAHL (1982-June 2006), pre-CINAHL, and Cochrane Library (2006, issue 3) electronic databases on 1 August 2006 for the following terms: sepsis, septic shock, severe sepsis, human clinical trials. We also hand-searched references and our personal files. Studies were selected if they met all of the following criteria: randomized, controlled trial study design; enrollment of adult patients with sepsis; presence of a hemodynamic goal for patient management; > 24-hour follow-up; and survival included as an outcome. Studies were independently selected and reviewed by two investigators.

RESULTS

A total of 6,006 citations were retrieved, and 13 eligible articles were reviewed. Mean arterial pressure was a treatment goal in nine studies, and systolic blood pressure was a treatment goal in three studies. A goal for pulmonary artery occlusion pressure, central venous pressure, and cardiac index was given in four, three, and five studies, respectively. The range of hemodynamic goals used in the trials were: mean arterial pressure 60-100 mmHg, central venous pressure 6-13 mmHg, pulmonary artery occlusion pressure 13-17 mmHg, and cardiac index 3-6 l/min/m2. All trials that used a systolic blood pressure goal used 90 mmHg as the aim.

CONCLUSION

For those trials that specify hemodynamic goals, the wide range of treatment targets suggest a lack of agreement on blood pressure and filling pressure goals for management of patients with sepsis. There was also inconsistency between trials in which measures were targeted. Further research is necessary to determine whether this lack of consistency in hemodynamic goals may contribute to heterogeneity in treatment effects for clinical trials of novel sepsis therapies.

A reappraisal of isoproterenol in goal-directed therapy of septic shock

The goal of the study was to evaluate the effect of isoproterenol prescribed in goal-directed therapy for septic shock. Out of a cohort of 89 patients with septic shock, 14 patients treated with fluid and norepinephrine had inappropriate mixed venous oxygen saturation (SvO2<70%) not responding to correction of hypoxemia and anemia (>8 g.dL-1). Isoproterenol administration was started at a dose of 0.04 microg.kg-1.minute-1 with 0.025 microg.kg-1.minute-1 increments every 30 minutes until SvO2 was greater than 70%. Mean arterial pressure was maintained>or=65 mm.Hg by adjusting the norepinephrine infusion. Hemodynamic, oxygen, and renal variables were collected during a 12-h period. Patients with a known prior history of coronary disease were not eligible. Isoproterenol administration increased significantly SvO2 (62%+/-10% to 71%+/-9%), cardiac index (3.1+/-0.6 to 4.4+/-1.4 L.min-1.m-2), stroke index (27+/-3.4 to 38+/-6.1 mL.m-2), and left ventricular stroke work index (24+/-3.4 to 40+/-5.0 g.m-1.m-2). Heart rate rise did not reach a significant level. Arterial lactate concentration decreased significantly during the study period (5.7+/-2.8 to 3.4+/-1.6 mmol.L-1). No cardiac adverse events occurred with any electrocardiographic aspects of myocardial ischemia. This study suggests that isoproterenol is efficient to improve hemodynamics and oxygen variables in septic shock patients. There is a need for future investigations in larger groups of patients to determine whether isoproterenol can be an alternative to dobutamine.

Early goal-directed therapy in severe sepsis and septic shock revisited: concepts, controversies, and contemporary findings

Studies of acute myocardial infarction, trauma, and stroke have been translated into improved outcomes by earlier diagnosis and application of therapy at the most proximal stage of hospital presentation. Most therapies for these diseases are instituted prior to admission to an ICU; this approach to the sepsis patient has been lacking. In response, a trial comparing early goal-directed therapy (EGDT) vs standard care was performed using specific criteria for the early identification of high-risk sepsis patients, verified definitions, and a consensus-derived protocol to reverse the hemodynamic perturbations of hypovolemia, vasoregulation, myocardial suppression, and increased metabolic demands. Five years after the EGDT publication, there has been much discussion generated with regard to the concepts of EGDT, as well as debate fueled regarding diagnostic and therapeutic interventions. However, during this time period further investigations by the primary investigators and others have brought additional contemporary findings. EGDT modulates some of the components of inflammation, as reflected by improved organ function. The end points used in the EGDT protocol, the outcome results, and the cost-effectiveness have subsequently been externally validated, revealing similar or even better findings than those from the original trial. Although EGDT is faced with challenges, a coordinated approach to sepsis management is necessary to duplicate the progress in outcomes seen in patients with conditions such as acute myocardial infarction, stroke, and trauma.

Rescue therapy in septic shock--is terlipressin the last frontier?

Use of terlipressin, an analogue of vasopressin, can be considered in septic shock patients with intractable hypotension and high cardiac output in whom fluid resuscitation and high-dose conventional catecholamines have failed. The effects of this agent on organ function are poorly evaluated in humans. The limited number of patients evaluated precludes any analysis of adverse outcomes and prognosis.

Small volume of hypertonic saline as the initial fluid replacement in experimental hypodynamic sepsis

INTRODUCTION

We conducted the present study to examine the effects of hypertonic saline solution (7.5%) on cardiovascular function and splanchnic perfusion in experimental sepsis.

METHODS

Anesthetized and mechanically ventilated mongrel dogs received an intravenous infusion of live Escherichia coli over 30 minutes. After 30 minutes, they were randomized to receive lactated Ringer's solution 32 ml/kg (LR; n = 7) over 30 minutes or 7.5% hypertonic saline solution 4 ml/kg (HS; n = 8) over 5 minutes. They were observed without additional interventions for 120 minutes. Cardiac output (CO), mean arterial pressure (MAP), portal and renal blood flow (PBF and RBF, respectively), gastric partial pressure of CO2 (pCO2; gas tonometry), blood gases and lactate levels were assessed.

RESULTS

E. coli infusion promoted significant reductions in CO, MAP, PBF and RBF (approximately 45%, 12%, 45% and 25%, respectively) accompanied by an increase in lactate levels and systemic and mesenteric oxygen extraction (sO2ER and mO2ER). Widening of venous-arterial (approximately 15 mmHg), portal-arterial (approximately 18 mmHg) and gastric mucosal-arterial (approximately 55 mmHg) pCO2 gradients were also observed. LR and HS infusion transiently improved systemic and regional blood flow. However, HS infusion was associated with a significant and sustained reduction of systemic (18 +/- 2.6 versus 38 +/- 5.9%) and mesenteric oxygen extraction (18.5 +/- 1.9 versus 36.5 +/- 5.4%), without worsening other perfusional markers.

CONCLUSION

A large volume of LR or a small volume of HS promoted similar transient hemodynamic benefits in this sepsis model. However, a single bolus of HS did promote sustained reduction of systemic and mesenteric oxygen extraction, suggesting that hypertonic saline solution could be used as a salutary intervention during fluid resuscitation in septic patients.

Dopexamine and norepinephrine versus epinephrine on gastric perfusion in patients with septic shock: a randomized study [NCT00134212]

Introduction

Microcirculatory blood flow, and notably gut perfusion, is important in the development of multiple organ failure in septic shock. We compared the effects of dopexamine and norepinephrine (noradrenaline) with those of epinephrine (adrenaline) on gastric mucosal blood flow (GMBF) in patients with septic shock. The effects of these drugs on oxidative stress were also assessed.

Methods

This was a prospective randomized study performed in a surgical intensive care unit among adults fulfilling usual criteria for septic shock. Systemic and pulmonary hemodynamics, GMBF (laser-Doppler) and malondialdehyde were assessed just before catecholamine infusion (T₀), as soon as mean arterial pressure (MAP) reached 70 to 80 mmHg (T₁), and 2 hours (T₂) and 6 hours (T₃) after T₁. Drugs were titrated from 0.2 μg kg^-1 min^-1 with 0.2 μg kg^-1 min^-1 increments every 3 minutes for epinephrine and norepinephrine, and from 0.5 μg kg^-1 min^-1 with 0.5 μg kg^-1 min^-1 increments every 3 minutes for dopexamine.

Results

Twenty-two patients were included (10 receiving epinephrine, 12 receiving dopexamine–norepinephrine). There was no significant difference between groups on MAP at T₀, T₁, T₂, and T₃. Heart rate and cardiac output increased significantly more with epinephrine than with dopexamine–norepinephrine, whereas. GMBF increased significantly more with dopexamine–norepinephrine than with epinephrine between T₁ and T₃ (median values 106, 137, 133, and 165 versus 76, 91, 90, and 125 units of relative flux at T₀, T₁, T₂ and T₃, respectively). Malondialdehyde similarly increased in both groups between T₁ and T₃.

Conclusion

In septic shock, at doses that induced the same effect on MAP, dopexamine–norepinephrine enhanced GMBF more than epinephrine did. No difference was observed on oxidative stress.

Emerging drugs for the treatment of sepsis

Septic shock still places a major burden on the healthcare system, although recent years have been marked by the demonstration that corticosteroids and activated protein C may substantially improve survival in selected populations. This review discusses the current management of septic shock and the potential development of new therapeutics following impressive advances in the pathomechanisms of septic shock.

Arterial minus end-tidal CO2 as a prognostic factor of hospital survival in patients resuscitated from cardiac arrest

AIMS

The purpose of this study was to determine the clinical value of arterial minus end-tidal CO(2) [P(a-et)CO(2)] and alveolar dead space ventilation ratio (V(dA)/V(t)) as indicators of hospital mortality in patients that have been resuscitated from cardiac arrest at emergency department.

MATERIALS AND METHODS

Forty-four patients with a return of spontaneous circulation (ROSC) after cardiac arrest were studied in the emergency department of a university teaching hospital from March 2004 to February 2006. Mean arterial pressure (MAP), serum lactate, arterial blood gas studies, end-tidal CO(2) (EtCO(2)), P(a-et)CO(2), and V(dA)/V(t) were evaluated at 1 h after ROSC. We compared these variables between hospital survivors and non-survivors.

RESULTS

The rates of ventricular fibrillation and pulseless ventricular tachycardia in hospital survivors were higher than those of non-survivors (53.0 and 9.7%, respectively, p=0.002). Hospital survivors had significantly higher MAP, lower serum lactate, lower P(a-et)CO(2), and lower V(dA)/V(t) value than non-survivors. Receiver operator characteristic (ROC) curves of serum lactate, P(a-et)CO(2), and V(dA)/V(t) showed significant sensitivity and specificity for hospital mortality. Specifically, lactate > or = 10.0 mmol/L, P(a-et)CO(2) > or = 12.5 mmHg, and V(dA)/V(t) > or = 0.348 were all associated with high hospital mortality (p=0.000, 0.001 and 0.000, respectively).

CONCLUSIONS

This study showed that high serum lactate, high P(a-et)CO(2) and high V(dA)/V(t) during early ROSC in cardiac arrest patients suggest high hospital mortality. If future studies validate this model, the P(a-et)CO(2) and V(dA)/V(t) may provide useful guidelines for the early post-resuscitation care of cardiac arrest patients in emergency departments.

Early microcirculatory perfusion derangements in patients with severe sepsis and septic shock: relationship to hemodynamics, oxygen transport, and survival

STUDY OBJECTIVE

To study early microcirculatory perfusion indices in patients with severe sepsis/septic shock, compare early microcirculatory indices in sepsis survivors versus nonsurvivors, and identify systemic hemodynamic/oxygen transport variables that correlate with early microcirculatory perfusion indices.

METHODS

This prospective observational study used orthogonal polarization spectral imaging to directly visualize the sublingual microcirculation in patients with severe sepsis/septic shock treated with early goal-directed therapy. We performed initial imaging within 6 hours of early goal-directed therapy initiation and late follow-up studies at 24-hour intervals until death or resolution of organ dysfunction. We imaged 5 sublingual sites and analyzed the data offline in a blinded fashion. We calculated 3 microcirculatory perfusion indices: flow velocity score, flow heterogeneity index, and capillary density. We analyzed early data to compare survivors versus nonsurvivors and examine correlations with systemic hemodynamic measurements. We used a linear mixed-effects model for longitudinal analyses.

RESULTS

We performed 66 orthogonal polarization spectral studies in 26 sepsis patients. Early microcirculatory indices were more markedly impaired (lower flow velocity and more heterogeneous perfusion) in nonsurvivors compared with survivors. These same early indices, flow velocity and heterogeneity, were also more markedly impaired with increasing severity of systemic cardiovascular dysfunction (lower arterial pressure or increasing vasopressor requirement).

CONCLUSION

Early microcirculatory perfusion indices in severe sepsis and septic shock are more markedly impaired in nonsurvivors compared with survivors and with increasing severity of global cardiovascular dysfunction.

The role of bundles in sepsis care

The understanding of the pathogenesis of sepsis has substantially changed in past years and continues to improve. New therapeutic options are being developed and incorporated into clinical practice. There are different specific interventions and therapies that benefit patients' outcome. As demonstrated by the early goal-directed therapy strategy, the success of the resuscitation treatment is strongly time dependent. The recognition of severe sepsis should be accompanied without delay by very well defined therapeutic measures. In 2002 the Surviving Sepsis Campaign was introduced with the overall goal of increasing clinicians' awareness and improving outcome in severe sepsis and septic shock.

Management of sepsis in the critically ill patient: key aspects

Severe sepsis is a major cause of morbidity and mortality in the critically ill patient. Management involves identification and treatment of the underlying causative infection, with antimicrobial agents and surgery where necessary, haemodynamic resuscitation with fluids and vasoactive agents, steroids (for septic shock) and immunomodulation with drotrecogin-alpha (activated), where not contraindicated. Every effort must be made to identify sepsis early so as to optimise the patient's chances of a good outcome.

Failure to implement evidence-based clinical guidelines for sepsis at the ED

OBJECTIVE

The main objective was to evaluate if consensus "bundle" measures to optimize the treatment of sepsis have been integrated in our routine practice. We also tried to identify variables significantly associated to mortality.

METHODS

An observational, unblinded study of those patients who, according to their physicians, met criteria for sepsis under its different stages of severity was conducted. Six items as proposed by surviving sepsis campaign were evaluated: (1) measurement of blood lactate; (2) obtaining blood samples for culture before use of antibiotics; (3) early use of antibiotics (>3 h); (4) fluid replacement with at least 20 mL/kg of crystalloids in the first hour, unless contraindicated, if hypotension or blood lactate >4 mmol/L; (5) use of vasoactive drugs, other than dopaminergic doses of dopamine, if hypotension or shock; (6) measurement of central venous pressure and central venous O2 saturation in shock. Data concerning several aspects of diagnosis, treatment, and consultation to ICU were collected.

RESULTS

Compliance with published guidelines is poor after evaluating the 6 items proposed: 12.5% of shocked patients had determinations of blood lactate; 15% of septic patients had no blood cultures drawn; 32% had received their first dose of antibiotics in the first 3 hours after admission; 46.6% of the cases of severe sepsis or shock received a fluid aggressive therapy; 43.3% of the patients with an indication for vasoactive drugs received them; no patient had central venous pressure monitoring at the ED. In addition, intensive care specialists were seldom consulted (17%). Having used dopaminergic doses of dopamine and having a respiratory focus as a source of infection were independently associated to mortality, respective OR: 21 ([1.7-254.9]; 95% CI) and 9.6 ([1.7-52]; 95% CI).

CONCLUSIONS

The "bundle" measures proposed in the surviving sepsis campaign seem not to have had enough impact in our ED. This is the start point of a "plan-do-study-act" process directed to improve the outcome of patients with sepsis at our institution.

The value of sepsis definitions in daily ICU-practice

Sepsis is a major disease entity with important clinical and economic implications. Sepsis is the hosts' reaction to infection and is characterized by a systemic inflammatory response. Because of difficulties in defining sepsis, the SIRS was introduced trying to summarize the inflammatory response in a limited set of elementary characteristics (fever or hypothermia, leucocytosis or leucopenia, tachycardia, hyperventilation). In daily practice it is essential to identify septic patients as soon as possible because early recognition results in better survival rates. However, in order to allow early detection, a more stringent description of "the septic profile" is needed. From the start, even after revision of the primary sepsis description, these definitions have caused much controversy and debate because they lack sensitivity and specificity. Conclusively, almost all patients admitted to the intensive care unit meet or develop the systemic inflammatory response syndrome. Therefore, it is difficult to distinguish patients with true sepsis from those with severe inflammation due to non-infectious causes. This review highlights the current sepsis definitions, and discusses their strengths as well as their shortcomings for daily intensive care unit practice.

Heterogeneity and prediction of hemodynamic responses to dobutamine in patients with septic shock

OBJECTIVE

To establish the heterogeneity of hemodynamic responses to dobutamine in patients with septic shock and to identify the predictive factors of these hemodynamic responses.

DESIGN

Prospective study.

SETTING AND PATIENTS

A total of 12 patients with septic shock in a tertiary medical intensive care unit.

INTERVENTIONS

A 20-min dobutamine infusion at 5 microg.kg(-1).min(-1) with subsequent increments to 8, 12.6, and 20 microg.kg(-1).min(-1), on two consecutive days. Responses were dichotomized into changes in heart rate (HR) or stroke volume index (SVI) of >10% and < or =10% at the maximal dobutamine infusion.

MEASUREMENTS AND MAIN RESULTS

No differences were found in survival, Acute Physiology and Chronic Health Evaluation II score, maximal dobutamine doses, or pharmacokinetics of dobutamine between HR and SVI groups. In DeltaHR > 10% vs. DeltaHR < or = 10%, baseline HR was lower, and baseline mixed venous oxygen tension and saturation were higher. During dobutamine infusion, mean arterial pressure decreased in DeltaHR > 10%. Cardiac index and the systemic oxygen delivery index increased and the systemic vascular resistance index decreased at unchanged SVI. Pressure work index increased and the ratio of the diastolic to systolic aortic pressure time indices decreased but not to <0.6. In DeltaHR < or = 10%, systemic vascular resistance index and the ratio of the diastolic to systolic aortic pressure time indices decreased (but remained >0.6) without changes in SVI or cardiac index. Baseline hemodynamic and metabolic variables did not differ between SVI groups. In DeltaSVI > 10%, cardiac index increased with dobutamine, but Pao2 and the systemic oxygen delivery index decreased. In DeltaSVI < or = 10%, HR and the systemic oxygen delivery index increased; mean arterial pressure, left ventricular stroke work index, systemic vascular resistance index, and the ratio of the diastolic to systolic aortic pressure time indices decreased.

CONCLUSIONS

Patients with a positive chronotropic response to dobutamine had lower baseline HR values, and a chronotropic rather than inotropic response predicted an increase in cardiac index and systemic oxygen delivery index. Incremental dosages of dobutamine did not compromise indirectly measured myocardial oxygen balance.

Nitric oxide involvement in the hemodynamic response to fluid resuscitation in endotoxic shock in rats

OBJECTIVE

Fluid loading is an essential part of cardiovascular resuscitation in septic shock. We hypothesized that fluid administration increases blood flow velocity and thus endothelial shear stress, causing the release of nitric oxide by the vascular endothelium. Because of endothelial dysfunction in sepsis, this mechanism would be less effective in septic animals. Fluid loading may have different effects in septic compared with control animals.

DESIGN

Prospective, randomized, controlled study.

SETTING

Animal research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

We tested the involvement of nitric oxide in the fluid-induced cardiovascular response after administration of lipopolysaccharide (5 mg/kg, n = 10) or vehicle (control, n = 10) in rats subsequently randomized after 165 mins to receive L-N(G)-nitroarginine (7.5 mg/kg) or saline (n = 5 in each group). At 180 mins, all animals received hydroxyethyl starch (fluid loading, 15 mL/kg in 15 mins). Reversal of L-N(G)-nitroarginine was studied with an intravenous bolus of L-arginine (300 mg/kg).

MEASUREMENTS AND MAIN RESULTS

Lipopolysaccharide injection induced a hypokinetic shock (low blood pressure: -30% +/- 9%, p < .05), low cardiac output (aortic pulsed-Doppler probe: -20% +/- 8, p < .05), and unchanged systemic conductance, which turned into a hyperkinetic shock by fluid loading. Pretreatment with L-N(G)-nitroarginine totally abolished this fluid loading-induced vasodilation in control rats but only partially in lipopolysaccharide-treated rats, suggesting an altered endothelial response after lipopolysaccharide injection. Maximal aortic blood flow acceleration was used as an index of left ventricular systolic function. The improvement of maximal aortic blood flow acceleration observed during fluid loading in lipopolysaccharide-treated or control animals was blunted by L-N(G)-nitroarginine pretreatment, suggesting the involvement of nitric oxide in the myocardial response to fluid loading.

CONCLUSIONS

These results suggest that the endothelium participates in the hemodynamic response to fluid loading in control rats, but less in rats with septic shock, secondary to an altered nitric oxide-dependent vasodilation.

Systemic and regional hemodynamic effects of enalaprilat infusion in experimental normotensive sepsis

Angiotensin-converting enzyme inhibitors have been shown to improve splanchnic perfusion in distinct shock states. We hypothesized that enalaprilat potentiates the benefits of early fluid resuscitation in severe experimental sepsis, particularly in the splanchnic region. Anesthetized and mechanically ventilated mongrel dogs received an intravenous infusion of live Escherichia coli over a period of 30 min. Thereafter, two interventions were performed: fluid infusion (normal saline, 32 mL/kg over 30 min) and enalaprilat infusion (0.02 mg kg(-1) min(-1) for 60 min) in randomized groups. The following groups were studied: controls (fluid infusion, N = 4), E1 (enalaprilat infusion followed by fluid infusion, N = 5) and E2 (fluid infusion followed by enalaprilat infusion, N = 5). All animals were observed for a 120 min after bacterial infusion. Mean arterial pressure, cardiac output (CO), portal vein blood flow (PVBF), systemic and regional oxygen-derived variables, and lactate levels were measured. Rapid and progressive reductions in CO and PVBF were induced by the infusion of live bacteria, while minor changes were observed in mean arterial pressure. Systemic and regional territories showed a significant increase in oxygen extraction and lactate levels. Widening venous-arterial and portal-arterial pCO2 gradients were also detected. Fluid replacement promoted transient benefits in CO and PVBF. Enalaprilat after fluid resuscitation did not affect systemic or regional hemodynamic variables. We conclude that in this model of normotensive sepsis inhibition of angiotensin-converting enzyme did not interfere with the course of systemic or regional hemodynamic and oxygen-derived variables.

Is the current management of severe sepsis and septic shock really evidence based?

Vincent discusses the reasons why evidence-based medicine may be particularly difficult to apply in the management of patients with severe sepsis.

Accuracy of weight and height estimation in an intensive care unit: Implications for clinical practice and research

OBJECTIVE

Numerous calculations routinely used in the intensive care require the knowledge of patients' weight and height, although these measurements are not always made. Estimates by doctors or nurses are often substituted. This study sought to ascertain the accuracy of estimates of weight and height of patients made by intensive care unit (ICU) staff.

DESIGN

: Prospective clinical study.

SETTING

Sixteen-bed mixed medical and surgical ICU in a university teaching hospital.

PATIENTS

Fourteen patients had their height and weight estimated by 20 members of the medical and nursing staff.

MEASUREMENTS

After all estimates had been recorded, measurements of weight and height were obtained. Weight was measured by means of a patient hoist with a calibrated weighing facility and height using a steel tape measure.

MAIN RESULTS

Estimation of weight was poor, with 47% of estimates at least 10% different and 19% of estimates at least 20% different from the measured values. The majority of height estimates were within 10% of the measured values.

CONCLUSIONS

Individual estimates of weight and height are frequently inaccurate. These errors of estimation could compromise application of effective therapies, as well as contribute to a reduction in design sensitivity of clinical trials.

Pharmacokinetics of unbound linezolid in plasma and tissue interstitium of critically ill patients after multiple dosing using microdialysis

The antimicrobial agent linezolid is approved for the treatment of severe infections caused by, e.g., methicillin-resistant Staphylococcus strains. In order to evaluate the penetration of linezolid into the interstitial space fluid (ISF) of subcutaneous adipose tissue and skeletal muscle of the target population, a microdialysis study was performed with 12 patients with sepsis or septic shock after multiple intravenous infusions. Unbound linezolid concentrations were determined for plasma and microdialysates by use of a validated high-performance liquid chromatography method. Individual compartmental pharmacokinetic (PK) analysis was performed using WinNonlin. In vivo microdialysis was found to be feasible for the determination of unbound linezolid concentrations at steady state in the ISF of critically ill patients. On average, linezolid showed good distribution into ISF but with high interindividual variability. A two-compartment model was fitted to unbound concentrations in plasma with a geometric mean distribution volume of 62.9 liters and a mean clearance of 9.18 liters/h at steady state. However, disposition characteristics changed intraindividually within the time course. In addition, an integrated model for simultaneous prediction of concentrations in all matrices was developed and revealed similar results. Based on the model-predicted unbound concentrations in ISF, a scheme of more-frequent daily dosing of linezolid for some critically ill patients might be taken into consideration to avoid subinhibitory unbound concentrations in the infected tissue. The developed integrated model will be a valuable basis for further PK data analysis to explore refined dosing guidelines that achieve effective antimicrobial therapy in all patients by use of the population PK approach.

The effect of normal saline resuscitation on vital organ blood flow in septic sheep

OBJECTIVE

To study the effect of resuscitation with normal saline on vital organ blood flow and renal function in sepsis.

DESIGN AND SETTING

Randomized controlled cross-over animal study in the animal laboratory of university physiology institute.

SUBJECTS

Six merino cross-ewes.

INTERVENTIONS

Chronic implantation of flow probes around aorta, coronary, renal and mesenteric arteries. Intravenous administration of live Escherichia coli. Random allocation to normal saline resuscitation (20 ml/kg over 15 min) or observation (control) for 210 min. Continuous measurement of central haemodynamics, organ blood flow and renal function.

RESULTS

Live E. coli induced hyperdynamic sepsis with oliguria (28.3 +/- 12.6 to 16.7 +/- 11.9 ml/30 min) and reduced creatinine clearance (87.9 +/- 24.5 to 44.3 +/- 34.5 ml/min). During this septic state mesenteric, coronary and renal blood flow increased. During the first hour (early effect) after saline resuscitation, central venous pressure, cardiac output, stroke volume, coronary blood flow, mesenteric blood flow, urine output and creatinine clearance increased, but there was no change in renal blood flow. In the following 2 h these increments were significantly attenuated, but urine output and creatinine clearance remained greater than controls; renal blood flow decreased slightly and the fractional excretion of sodium increased significantly.

CONCLUSION

In hyperdynamic sepsis resuscitation with normal saline increases central venous pressure, cardiac output, mesenteric blood flow, urine output, creatinine clearance, and fractional excretion of sodium despite a lack of effect on renal blood flow. These effects, however, are transient.

Echocardiographic measurement of fluid responsiveness

PURPOSE OF REVIEW

Fluid responsiveness is a relatively new concept. It enables the efficacy of volume expansion to be predicted before use, rather than assessed afterwards, thus avoiding inappropriate fluid infusion. Echocardiography is a fantastic noninvasive tool which can directly visualize the heart and assess cardiac function. Its use was long limited by the absence of accurate indices to diagnose hypovolemia and predict the effect of volume expansion. In the last few years, several French teams have used echocardiography to develop new parameters of fluid responsiveness, taking advantage of its ability to monitor cardiac function beat by beat during the respiratory cycle.

RECENT FINDINGS

In mechanically ventilated patients perfectly adapted to the respirator, respiratory variations in superior and inferior vena cava diameters and in left ventricular stroke volume have been validated as parameters of fluid responsiveness. In our opinion, the collapsibility index of the superior vena cava is the most reliable of these parameters, but does require transesophageal echocardiography.

SUMMARY

Echocardiography has been widely demonstrated to predict fluid responsiveness accurately. This is now a complete and noninvasive tool able to accurately determine hemodynamic status in circulatory failure.

Severe sepsis and septic shock: review of the literature and emergency department management guidelines

Severe sepsis and septic shock are as common and lethal as other acute life-threatening conditions that emergency physicians routinely confront such as acute myocardial infarction, stroke, and trauma. Recent studies have led to a better understanding of the pathogenic mechanisms and the development of new or newly applied therapies. These therapies place early and aggressive management of severe sepsis and septic shock as integral to improving outcome. This independent review of the literature examines the recent pathogenic, diagnostic, and therapeutic advances in severe sepsis and septic shock for adults, with particular relevance to emergency practice. Recommendations are provided for therapies that have been shown to improve outcomes, including early goal-directed therapy, early and appropriate antimicrobials, source control, recombinant human activated protein C, corticosteroids, and low tidal volume mechanical ventilation.

Effects of epinephrine, norepinephrine, and phenylephrine on microcirculatory blood flow in the gastrointestinal tract in sepsis*

OBJECTIVE

The use of vasopressors for treatment of hypotension in sepsis may have adverse effects on microcirculatory blood flow in the gastrointestinal tract. The aim of this study was to measure the effects of three vasopressors, commonly used in clinical practice, on microcirculatory blood flow in multiple abdominal organs in sepsis.

DESIGN

Random order, cross-over design.

SETTING

University laboratory.

SUBJECTS

Eight sedated and mechanically ventilated pigs.

INTERVENTIONS

Pigs were exposed to fecal peritonitis-induced septic shock. Mesenteric artery flow was measured using ultrasound transit time flowmetry. Microcirculatory flow was measured in gastric, jejunal, and colon mucosa; jejunal muscularis; and pancreas, liver, and kidney using multiple-channel laser Doppler flowmetry. Each animal received a continuous intravenous infusion of epinephrine, norepinephrine, and phenylephrine in a dose increasing mean arterial pressure by 20%. The animals were allowed to recover for 60 mins after each drug before the next was started.

MEASUREMENTS AND MAIN RESULTS

During infusion of epinephrine (0.8 +/- 0.2 mug/kg/hr), mean arterial pressure increased from 66 +/- 5 to 83 +/- 5 mm Hg and cardiac index increased by 43 +/- 9%. Norepinephrine (0.7 +/- 0.3 mug/kg/hr) increased mean arterial pressure from 70 +/- 4 to 87 +/- 5 mm Hg and cardiac index by 41 +/- 8%. Both agents caused a significant reduction in superior mesenteric artery flow (11 +/- 4%, p < .05, and 26 +/- 6%, p < .01, respectively) and in microcirculatory blood flow in the jejunal mucosa (21 +/- 5%, p < .01, and 23 +/- 3%, p < .01, respectively) and in the pancreas (16 +/- 3%, p < .05, and 8 +/- 3%, not significant, respectively). Infusion of phenylephrine (3.1 +/- 1.0 mug/kg/min) increased mean arterial pressure from 69 +/- 5 to 85 +/- 6 mm Hg but had no effects on systemic, regional, or microcirculatory flow except for a 30% increase in jejunal muscularis flow (p < .01).

CONCLUSIONS

Administration of the vasopressors phenylephrine, epinephrine, and norepinephrine failed to increase microcirculatory blood flow in most abdominal organs despite increased perfusion pressure and-in the case of epinephrine and norepinephrine-increased systemic blood flow. In fact, norepinephrine and epinephrine appeared to divert blood flow away from the mesenteric circulation and decrease microcirculatory blood flow in the jejunal mucosa and pancreas. Phenylephrine, on the other hand, appeared to increase blood pressure without affecting quantitative blood flow or distribution of blood flow.

Dobutamine does not influence inflammatory pathways during human endotoxemia*

OBJECTIVE

Catecholamines have anti-inflammatory and anticoagulant properties. Dobutamine is a synthetic catecholamine frequently used in patients with septic myocardial dysfunction. The objective was to determine whether a continuous infusion of dobutamine exerts immunomodulatory effects in healthy volunteers challenged with endotoxin.

DESIGN

Prospective, open-label study.

SETTING

Clinical research unit of a university hospital.

PARTICIPANTS

Sixteen male healthy volunteers.

INTERVENTIONS

Volunteers received a constant infusion with dobutamine (10 microg.kg.min, n = 8) or physiologic saline (n = 8). All participants were challenged with a bolus injection of endotoxin prepared from Escherichia coli (4 ng/kg). Dobutamine infusion was commenced 1 hr before endotoxin challenge and was continued until 3 hrs thereafter.

MEASUREMENTS AND MAIN RESULTS

Dobutamine infusion was associated with an increase in mean arterial blood pressure (peak 122 +/- 5 mm Hg) and heart rate (peak 84 +/- 4 beats/min, both p < .05 vs. saline). Endotoxin injection induced the systemic release of cytokines (tumor necrosis factor-alpha, interleukins-6, -8, and -10) and secretory phospholipase A2, endothelial cell activation (increase in the plasma levels of soluble E-selectin and von Willebrand factor), activation of coagulation (increased plasma levels of soluble tissue factor, F1 + 2 prothrombin fragment, and thrombin-antithrombin complexes), and activation with subsequent inhibition of fibrinolysis (increased plasma concentrations of tissue-type plasminogen activator, plasminogen activator inhibitor type I, and plasmin-alpha2-antiplasmin complexes). None of these responses were influenced by dobutamine.

CONCLUSIONS

Dobutamine, infused in a clinically relevant dose, does not influence inflammatory and coagulant pathways during human endotoxemia.

Does dopamine administration in shock influence outcome? Results of the Sepsis Occurrence in Acutely Ill Patients (SOAP) Study

OBJECTIVE

The optimal adrenergic support in shock is controversial. We investigated whether dopamine administration influences the outcome from shock.

DESIGN

Cohort, multiple-center, observational study.

SETTING

One hundred and ninety-eight European intensive care units.

PATIENTS

All adult patients admitted to a participating intensive care unit between May 1 and May 15, 2002.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were followed up until death, until hospital discharge, or for 60 days. Shock was defined as hemodynamic compromise necessitating the administration of vasopressor catecholamines. Of 3,147 patients, 1,058 (33.6%) had shock at any time; 462 (14.7%) had septic shock. The intensive care unit mortality rate for shock was 38.3% and 47.4% for septic shock. Of patients in shock, 375 (35.4%) received dopamine (dopamine group) and 683 (64.6%) never received dopamine. Age, gender, Simplified Acute Physiology Score II, and Sequential Organ Failure Assessment score were comparable between the two groups. The dopamine group had higher intensive care unit (42.9% vs. 35.7%, p=.02) and hospital (49.9% vs. 41.7%, p=.01) mortality rates. A Kaplan-Meier survival curve showed diminished 30 day-survival in the dopamine group (log rank=4.6, p=.032). In a multivariate analysis with intensive care unit outcome as the dependent factor, age, cancer, medical admissions, higher mean Sequential Organ Failure Assessment score, higher mean fluid balance, and dopamine administration were independent risk factors for intensive care unit mortality in patients with shock.

CONCLUSIONS

This observational study suggests that dopamine administration may be associated with increased mortality rates in shock. There is a need for a prospective study comparing dopamine with other catecholamines in the management of circulatory shock.

Patient-safety and quality initiatives in the intensive-care unit

PURPOSE OF REVIEW

Patient safety has become the primary focus of health-care improvement in the last few years as an increasing body of evidence emphasizes the magnitude of harm posed to patients by medical errors. The intensive-care unit, by virtue of the high technology aggressive level of care the unit provides, has been identified as a significant source of patient harm. Consequently, the intensive-care unit also represents a tremendous opportunity to study and implement patient-safety initiatives, as significant improvements can be realized in this environment.

RECENT FINDINGS

Several broad areas of successful patient-safety initiatives have been reported over the recent past including implementation of Comprehensive Unit-based Safety Programs, introduction of communication tools (for example daily goal sheets), application of care bundles (that is mechanical ventilation or sepsis), as well as team approaches that can eradicate catheter-related bloodstream infections. Specific interventions are gaining supportive evidence and widespread acceptance for their ability to reduce harm including tight glucose control and ultrasonography for reducing central-line placement complications. Recent data also demonstrate the value of an intensivist as the team leader for the critically ill within the intensive-care unit and potentially with rapid-response teams.

SUMMARY

Many patient safety and quality-of-care initiatives that have broad application to all areas of medical care have been successfully developed in the intensive-care unit. The intensive-care unit appears to be a fertile ground for the development of safety initiatives.

Catecholamines and vasopressin during critical illness

In critical care medicine, catecholamines are most widely used to reverse circulatory dysfunction and thus to restore tissue perfusion. However, catecholamines not only influence systemic and regional hemodynamics, but also exert a variety of significant metabolic, endocrine, and immunologic effects. Arginine vasopressin is a vasomodulatory hormone with potency to restore vascular tone in vasodilatory hypotension. Although the evidence supporting the use of low doses of vasopressin or its analogs in vasodilatory shock is increasing, lack of data regarding mortality and morbidity prevent their implementation in critical care protocols.

Haemodynamic response to acute hypovolaemia, rapid blood volume expansion and adrenaline administration in an infant animal model

We performed a prospective experimental animal study in seven sedated and mechanically ventilated piglets weighing 9+/-0.8 kg, to assess the haemodynamic response to acute hypovolaemia, rapid blood volume expansion and adrenaline (epinephrine) administration in an infant animal model. Withdrawal of 20 mL/kg of blood (hypovolaemia), rapid infusion of 20 mL/kg of blood (expansion) and the administration of 0.01 mg/kg of adrenaline were made in each animal. Heart rate, mean blood pressure (MBP), central venous pressure (CVP), pulmonary capillary pressure (PCP), cardiac index (CI), systemic vascular resistance index (SVRI), left ventricular contractility (Dp/dtmax), blood volume variables, including intrathoracic blood volume index (ITBI), global end-diastolic volume (GEDVI) and extravascular lung water index (ELWI). Hypovolaemia produced a significant decrease in the pressure, volume and CI variables, with an increase in SVRI and a decrease in Dp/dtmax. After expansion, all variables returned towards normal, with persistence of the SVRI increase and Dp/dtmax decrease. Changes in the blood volume variables (ITBI and GEDVI) were larger than in the pressure variables (CVP, PCP) in the case of both hypovolaemia and expansion. Adrenaline caused a slight increase in heart rate, MBP, CVP, PCP and Dp/dtmax with a greater increase in SVRI. None of the interventions led to changes in ELWI. We conclude that acute hypovolaemia produces an increase in SVRI and a decrease in Dp/dtmax that does not return fully to normal with restoration of blood volume. ITBI and GEDVI are more sensitive to changes in blood volume than CVP and PCP. Rapid blood volume expansion and adrenaline administration do not affect extravascular lung water.

Cardiovascular response to dopamine and early prediction of outcome in septic shock: a prospective multiple-center study

OBJECTIVES

To compare mortality rates between dopamine-sensitive (Dopa-S) and dopamine-resistant (Dopa-R) septic shock patients, the latter group defined by a mean arterial pressure <70 mm Hg despite the use of 20 mug/kg/min dopamine.

DESIGN

A human, prospective observational, multiple-center, clinical trial.

SETTING

Ten intensive care units from ten hospitals.

PATIENTS

110 patients with septic shocks.

INTERVENTIONS

Following volume resuscitation, patients were treated by a rapid increase in dopamine infusion from 10 to 20 mug/kg/min. If mean arterial pressure remained <70 mm Hg, dopamine treatment was promptly switched to norepinephrine or epinephrine.

MEASUREMENTS AND MAIN RESULTS

Dopamine sensitivity, arterial gas, lactate, and organ system failure scores were measured at admission and after 6, 12, 24, 48, 72, 96, and 120 hrs. The overall 28-day mortality rate was 54% for the entire population under study. In multivariate analysis, independent predictors of death were dopamine resistance (odds ratio, 9.5; 95% confidence interval, 3-25), arterial lactate >3.5 mmol/L (odds ratio, 1.75; 95% confidence interval, 1.06-2.55), and Sepsis-related Organ Failure Assessment score >10 (odds ratio, 1.40; 95% confidence interval, 1.07-2.12). Of the 110 patients studied, 66 were observed to be resistant to dopamine (60%). In the Dopa-S group, the 28-day mortality rate was 16% (seven of 44 patients) compared with 78% (52 of 66 patients) in the Dopa-R group (p = .0006). The capacity of dopamine resistance to predict death was associated with a sensitivity of 84% and a specificity of 74%. At 24 hrs, the association of dopamine resistance to a lactate level >3.5 mmol/L improved the prognostic value (sensitivity, 90%, specificity, 92%).

CONCLUSIONS

Dopamine sensitivity is associated with decreased mortality rate. Early recognition of dopamine resistant septic shock could allow for better screening of patients with an ominous prognosis.

Fluid responsiveness in spontaneously breathing patients: A review of indexes used in intensive care

OBJECTIVE

In spontaneously breathing patients, indexes predicting hemodynamic response to volume expansion are very much needed. The present review discusses the clinical utility and accuracy of indexes tested as bedside indicators of preload reserve and fluid responsiveness in hypotensive, spontaneously breathing patients.

DATA SOURCE

We conducted a literature search of the MEDLINE database and the trial register of the Cochrane Group.

STUDY SELECTION

Identification of reports investigating, prospectively, indexes of fluid responsiveness in spontaneously breathing critically ill patients. All the studies defined the response to fluid therapy after measuring cardiac output and stroke volume using the thermodilution technique. We did not score the methodological quality of the included studies before the data analysis.

DATA EXTRACTION

A total of eight prospective clinical studies in critically ill patients were included. Only one publication evaluated cardiac output changes induced by fluid replacement in a selected population of spontaneously breathing critically ill patients.

DATA SYNTHESIS

Based on this review, we can only conclude that static indexes are valuable tools to confirm that the fluid volume infused reaches the cardiac chambers, and therefore these indexes inform about changes in cardiac preload. However, respiratory variation in right atrial pressure, which represents a dynamic measurement, seems to identify hypotension related to a decrease in preload and to distinguish between responders and nonresponders to a fluid challenge.

CONCLUSIONS

Further studies should address the question of the role of static indexes in predicting cardiac output improvement following fluid infusion in spontaneously breathing patients.

The Pulmonary Artery Catheter: Gold Standard or Redundant Relic

Pulmonary artery catheter (PAC) technology has changed significantly and use has decreased over the last 20 years. Barriers to use include: (a) increased patient risk with placement; (b) ability to measure similar variables via less invasive measures; (c) increased cost; (d) inaccurate measurement leading to misuse of PAC-derived variables; (e) incorrect interpretation and clinical application; and (f) lack of proven benefit for patient management. Advances in technology have allowed for continuous trending of hemodynamic parameters measured via the PAC. Patient risk is similar to that of central line placement; however risks associated with pulmonary artery infarction and rupture are inherent to the PAC. Less invasive assessment of cardiac output equals that of the PAC, whereas pulmonary capillary wedge pressure and mixed venous oxygen saturation monitoring are unique features of the PAC. Effective use of PAC data will require ongoing standardized education. More studies are needed on the cost-effectiveness of PAC monitoring as well as outcome benefits. Much of the data available from the PAC can be obtained via less invasive methods. However, the PAC continues to be useful in specific situations and remains the gold standard for comparison of new technologies. This paper discusses use of the PAC during the past 2 decades and reviews studies affecting its use in clinical practice.

Bench-to-bedside review: Is there a place for epinephrine in septic shock?

The use of epinephrine in septic shock remains controversial. Nevertheless, epinephrine is widely used around the world and the reported morbidity and mortality rates with it are no different from those observed with other vasopressors. In volunteers, epinephrine increases heart rate, mean arterial pressure and cardiac output. Epinephrine also induces hyperglycemia and hyperlactatemia. In hyperkinetic septic shock, epinephrine consistently increases arterial pressure and cardiac output in a dose dependent manner. Epinephrine transiently increases lactate levels through an increase in aerobic glycolysis. Epinephrine has no effect on splanchnic circulation in dopamine-sensitive septic shock. On the other hand, in dopamine-resistant septic shock, epinephrine has no effect on tonometric parameters but decreases fractional splanchnic blood flow with an increase in the gradient of mixed venous oxygen saturation (SVO₂) and hepatic venous oxygen saturation (SHO₂). In conclusion, epinephrine has predictable effects on systemic hemodynamics and is as efficient as norepinephrine in correcting hemodynamic disturbances of septic shock. Moreover, epinephrine is cheaper than other commonly used catecholamine regimens in septic shock. The clinical impact of the transient hyperlactatemia and of the splanchnic effects are not established.

Pre-ejection period variations predict the fluid responsiveness of septic ventilated patients

OBJECTIVES

In septic patients with acute circulatory failure, reliable predictors of fluid responsiveness are needed at the bedside. We hypothesized that the respiratory change in pre-ejection period (DeltaPEP) would allow the prediction of changes in cardiac index following volume administration in mechanically ventilated septic patients.

DESIGN

Prospective clinical investigation.

SETTING

A ten-bed hospital intensive care unit.

PATIENTS

Patients admitted after septic shock equipped with an arterial catheter.

INTERVENTIONS

Pre-ejection period (PEP)--defined as the time interval between the beginning of the R wave on the electrocardiogram and the upstroke of the radial arterial pressure curve (PEPKT) or the pulse plethysmographic waveforms (PEPPLET)--and cardiac index (transthoracic echocardiography-Doppler) were determined before and after volume infusion of colloid (8 mL x kg). DeltaPEP (%) was defined as the difference between expiratory and inspiratory PEP divided by the mean of expiratory and inspiratory values. Respiratory changes in pulse pressure (DeltaPP) was also measured.

MEASUREMENTS AND MAIN RESULTS

: Twenty-two volume challenges were done in 20 deeply sedated patients. DeltaPEPKT, DeltaPEPPLET, and DeltaPP (measured in all patients) before volume expansion were correlated with cardiac index change after fluid challenge (r = .73, r = .67, and r = .70, respectively, p < .0001). Patients with a cardiac index increase induced by volume expansion > or = 15% and <15% were classified as responders and nonresponders, respectively. Receiver operating characteristic curves showed that the threshold DeltaPP value of 17% allowed discrimination between responder/nonresponder patients with a sensitivity of 85% and a specificity of 100%. For both DeltaPEPKT and DeltaPEPPLET, the best threshold value was 4% with a sensitivity-specificity of 92%-89% and 100%-67%, respectively.

CONCLUSIONS

The present study found DeltaPEPKT and DeltaPEPPLET to be as accurate as DeltaPP in the prediction of fluid responsiveness in mechanically ventilated septic patients.