Cardiovascular management of septic shock

The Role of Vasopressin in Vasodilatory Septic Shock

Septic shock that requires therapy with adrenergic agents is associated with high rates of mortality. Inappropriately normal or low serum concentrations of vasopressin contribute to the development of hypotension during sepsis. We critically evaluated the role of administering exogenous vasopressin to patients with septic shock. A computerized search of MEDLINE from January 1966--December 2003 and a manual search of relevant journals for abstracts were conducted. Eleven retrospective, six prospective cohort, and four prospective randomized studies were identified. Most studies evaluated short-term infusions of vasopressin at 0.08 U/minute or less as add-on therapy in patients requiring adrenergic agents. The results show that starting vasopressin in patients with septic shock increases systemic vascular resistance and arterial blood pressure, thus reducing the dosage requirements of adrenergic agents. These effects are rapid and sustained. Substantial enhancement of urine production, likely due to increased glomerular filtration rate, was shown in several studies. A few studies demonstrated clinically significant reduced cardiac output or cardiac index after vasopressin was begun, necessitating cautious use in patients with cardiac dysfunction. Vasopressin was associated with ischemia of the mesenteric mucosa, skin, and myocardium; elevated hepatic transaminase and bilirubin concentrations; hyponatremia; and thrombocytopenia. Limiting the dosage to 0.03 U/minut or less may minimize the development of these adverse effects. Vasopressin 0.03 U/minute or less should be considered if response to one or two adrenergic agents is inadequate or as a method to reduce the dosage of adrenergic agents. At present, vasopressin therapy should not be started as first-line therapy. Additional studies are needed to determine the optimum dosage, duration, and place in therapy of vasopressin relative to adrenergic agents. A multicenter, comparative study of vasopressin 0.03 U/minute as add-on therapy is under way and should provide mortality data.

Endocrinologic response to vasopressin infusion in advanced vasodilatory shock

OBJECTIVES

To evaluate the endocrinologic response to a combined arginine vasopressin and norepinephrine (AVP/NE) infusion in advanced vasodilatory shock, and to examine the relationship between baseline plasma AVP concentrations and the hemodynamic response to AVP.

DESIGN

Preliminary, prospective, randomized, controlled clinical study.

SETTING

Twenty-three-bed general and surgical intensive care unit.

PATIENTS

Thirty-eight patients with advanced vasodilatory shock. Hemodynamic and laboratory data of 34 patients have already been presented in a recently published prospective, randomized, controlled study.

INTERVENTIONS

Continuous AVP (4 units/hr) and NE infusion in study patients; NE infusion only in control patients.

MEASUREMENTS AND MAIN RESULTS

At baseline, 24 hrs, and 48 hrs after randomization, plasma concentrations of AVP, adrenocorticotropic hormone, cortisol, renin, angiotensin II, aldosterone, prolactin, endothelin I, and atrial natriuretic factor were determined. Hemodynamic variables were recorded at baseline and 1, 12, and 24 hrs after randomization. Linear mixed effects models were used to test for differences between groups. The relationship between AVP plasma concentrations and hemodynamic response to AVP was analyzed using linear regression analyses. AVP/NE patients exhibited significantly higher AVP (p <.001) and prolactin (p <.001) plasma concentrations during the study period; there were no significant differences in plasma concentrations of other hormones. No significant correlation was detected between plasma AVP concentrations and the increase in mean arterial pressure after 1 hr (Pearson's correlation coefficient =.134, p =.584) and after 24 hrs (Pearson's correlation coefficient = -.198, p =.417). There were further no correlations between AVP plasma concentrations and the 24-hr response to AVP therapy in heart rate (Pearson's correlation coefficient = -.065, p =.791), stroke volume index (Pearson's correlation coefficient = -.106, p =.687), and NE requirements (Pearson's correlation coefficient =.04, p =.869).

CONCLUSIONS

The preliminary results of this study indicate that a combined AVP and NE infusion increases prolactin plasma concentrations in advanced vasodilatory shock. Hemodynamic effects of AVP infusion are independent of baseline plasma AVP concentrations.

Case review: septic shock in the pregnant patient

This case study involves a 36-year-old female at 15 weeks gestation who presented with severe lower abdominal pain post amniocentesis and subsequently deteriorated into a state of septic shock whilst in the ED. The circumstances surrounding this patient's presentation and subsequent clinical course are presented. The assessment and management of septic shock is also described with specific consideration to this patient's pregnant state.

Optimum treatment of severe sepsis and septic shock: evidence in support of the recommendations

Severe sepsis and septic shock are among the most common causes of death in noncoronary intensive care units. The incidence of sepsis has been increasing over the past two decades, and is predicted to continue to rise over the next 20 years. While our understanding of the complex pathophysiologic alterations that occur in severe sepsis and septic shock has increased greatly asa result of recent clinical and preclinical studies, mortality associated with the disorder remains unacceptably high. Despite these new insights, the cornerstone of therapy continues to be early recognition, prompt initiation of effective antibiotic therapy, and source control, and goal-directed hemodynamic, ventilatory,and metabolic support as necessary. To date, attempts to reduce mortality with innovative, predominantly anti-inflammatory therapeutic strategies have been extremely disappointing. Observations of improved outcomes with physiologic doses of corticosteroid replacement therapy and activated protein C (drotrecogin alfa[activated]) have provided new adjuvant therapies for severe sepsis and septic shock in selected patients. This article reviews the components of sepsis management and discusses the available evidence in support of these recommendations. In addition, there is a discussion of some promising new strategies.

Effects of continuous vasopressin infusion in patients with septic shock

BACKGROUND

Small studies have reported that vasopressin improves hemodynamic instability in patients with septic shock.

OBJECTIVE

To determine whether vasopressin infusion increases blood pressure, decreases catecholamine vasopressor use, and improves renal function in a large patient population with septic shock when used in a clinical setting.

METHODS

A retrospective chart audit was conducted of critically ill patients who received vasopressin infusion for septic shock from January 2000 through September 2002. Demographic, hemodynamic, laboratory, vasopressor, and adverse event data were collected. Statistical methods included ANOVA with Tukey's test for post hoc analysis.

RESULTS

A total of 102 of 353 patients met study criteria. The mean +/- SD vasopressin dosage regimen was 0.11 +/- 0.17 units/min for 53.8 +/- 71.5 hours. Compared with baseline, vasopressin infusion improved mean arterial pressure (MAP) by 15% within one hour (p < 0.05), reduced heart rate by 9% within 4 hours (p < 0.05), and reduced hourly dopamine dosage by 25% within 8 hours (p < 0.05). These effects persisted through 96 hours. Other hemodynamic variables and catecholamine vasopressor usage parameters were not statistically different from baseline. Urine output, serum creatinine, and serum sodium concentrations were not statistically changed from baseline. Adverse events possibly associated with vasopressin infusion included ischemic digits/extremities, myocardial infarction, and hyponatremia.

CONCLUSIONS

Vasopressin infusion was effective in increasing MAP and reducing heart rate while decreasing the dopamine dosage in patients with septic shock. Comparative studies with catecholamine vasopressors are needed to define the optimal role of vasopressin in septic shock therapy. In the meantime, vasopressin infusion at <or=0.03 units/min should be considered only if response to 1 or 2 catecholamine vasopressors is inadequate or as a method to reduce the dose of these therapies.

Clinical skills: assessing and treating shock: a nursing perspective

This article outlines the pathophysiology associated with hypovolaemic, cardiogenic and distributive shock, and discusses how each of these might present clinically in the patient. Nursing assessment of a patient in shock is explored, and the use of tools such as the pulse oximeter is examined. The evidence base for a variety of interprofessional interventions is analysed, including fluid therapies such as blood transfusion, the use of crystalloids and colloids, and drug therapies such as the use of inotropic and vasoactive agents. The nursing role in managing the patient in shock is considered throughout. The importance of recognizing the clinical presentation of shock is highlighted, with an emphasis on understanding the pathophysiology and potential systemic effects. Treatment is discussed and covers: providing optimal oxygen therapy, appropriate patient monitoring and location of care, using effective communication skills, assisting with activities of living, psychological support, and working collaboratively to maximize the overall quality of patient care delivered.

Transduction of NO-bioactivity by the red blood cell in sepsis: novel mechanisms of vasodilation during acute inflammatory disease

Sepsis is an acute inflammatory disease characterized by dysfunctional blood flow and hypotension. Nitric oxide (NO) is elevated during sepsis and plays an integral role in the associated vascular pathology. However, precise mechanisms and functions of NO in sepsis remain unclear. In this study, we show that red blood cells (RBCs) are foci for nitrosative reactions during acute inflammation, resulting in the formation of cells that can promote systemic vascular relaxation in an uncontrolled manner. Specifically, using experimental models of endotoxemia and surgical sepsis, NO adducts were found in the RBCs, including S-nitrosohemoglobin (SNOHb). These RBCs, referred to as septic RBCs, spontaneously stimulated vasodilation in a manner consistent with elevated SNOHb concentrations. Moreover, relaxation was cyclic guanosine monophosphate (cGMP) dependent and was inhibited by RBC lysis and glutathione but not by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5 tetramethylimidazoline 1-oxyl 3-oxide (C-PTIO). The potential mechanism of septic RBC-mediated vasorelaxation is discussed and may involve the intermediate, nitroxyl (HNO). Coupled with data showing that NO adducts in septic RBCs were dependent on the inducible nitric oxide synthase and correlated with plasma nitrite, these findings provide a novel framework to understand mechanisms underlying dysfunctional blood flow responses during sepsis. Specifically, the concept that RBCs directly mediate systemic hypotension through NO-dependent mechanisms is discussed.

Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for severe sepsis and septic shock that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

We used a modified Delphi methodology for grading recommendations, built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations were provided to contrast adult and pediatric management.

RESULTS

Key recommendations, listed by category and not by hierarchy, include early goal-directed resuscitation of the septic patient during the first 6 hrs after recognition; appropriate diagnostic studies to ascertain causative organisms before starting antibiotics; early administration of broad-spectrum antibiotic therapy; reassessment of antibiotic therapy with microbiology and clinical data to narrow coverage, when appropriate; a usual 7-10 days of antibiotic therapy guided by clinical response; source control with attention to the method that balances risks and benefits; equivalence of crystalloid and colloid resuscitation; aggressive fluid challenge to restore mean circulating filling pressure; vasopressor preference for norepinephrine and dopamine; cautious use of vasopressin pending further studies; avoiding low-dose dopamine administration for renal protection; consideration of dobutamine inotropic therapy in some clinical situations; avoidance of supranormal oxygen delivery as a goal of therapy; stress-dose steroid therapy for septic shock; use of recombinant activated protein C in patients with severe sepsis and high risk for death; with resolution of tissue hypoperfusion and in the absence of coronary artery disease or acute hemorrhage, targeting a hemoglobin of 7-9 g/dL; appropriate use of fresh frozen plasma and platelets; a low tidal volume and limitation of inspiratory plateau pressure strategy for acute lung injury and acute respiratory distress syndrome; application of a minimal amount of positive end-expiratory pressure in acute lung injury/acute respiratory distress syndrome; a semirecumbent bed position unless contraindicated; protocols for weaning and sedation/analgesia, using either intermittent bolus sedation or continuous infusion sedation with daily interruptions/lightening; avoidance of neuromuscular blockers, if at all possible; maintenance of blood glucose <150 mg/dL after initial stabilization; equivalence of continuous veno-veno hemofiltration and intermittent hemodialysis; lack of utility of bicarbonate use for pH > or =7.15; use of deep vein thrombosis/stress ulcer prophylaxis; and consideration of limitation of support where appropriate. Pediatric considerations included a more likely need for intubation due to low functional residual capacity; more difficult intravenous access; fluid resuscitation based on weight with 40-60 mL/kg or higher needed; decreased cardiac output and increased systemic vascular resistance as the most common hemodynamic profile; greater use of physical examination therapeutic end points; unsettled issue of high-dose steroids for therapy of septic shock; and greater risk of hypoglycemia with aggressive glucose control.

CONCLUSION

Evidence-based recommendations can be made regarding many aspects of the acute management of sepsis and septic shock that are hoped to translate into improved outcomes for the critically ill patient. The impact of these guidelines will be formally tested and guidelines updated annually and even more rapidly as some important new knowledge becomes as available.

Sepsis in the Interventional Radiology Patient

Interventional radiologists often treat patients who are at risk of becoming acutely septic while in the radiology department. Identifying those most at risk and initiating treatment plans before the acute situation are fundamental to this difficult group of patients. Treatment plans for life-threatening infection are based on controlling the source of infection and administering appropriate systemic antimicrobial therapy as well as volume and cardiopulmonary support. The purpose of this review is to provide a framework for the diagnosis and treatment of sepsis in the interventional radiology patient.

A new weapon against severe sepsis related to necrotizing fasciitis

Necrotizing fasciitis is a life-threatening infection. The purpose of this article is to review necrotizing fasciitis and nursing care as this disease may progress to sepsis.

Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock

OBJECTIVE

To develop management guidelines for severe sepsis and septic shock that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee. The modified Delphi methodology used for grading recommendations built upon a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along 5 levels to create recommendation grades from A-E, with A being the highest grade. Pediatric considerations were provided to contrast adult and pediatric management.

PARTICIPANTS

Participants included 44 critical care and infectious disease experts representing 11 international organizations.

RESULTS

A total of 46 recommendations plus pediatric management considerations.

CONCLUSIONS

Evidence-based recommendations can be made regarding many aspects of the acute management of sepsis and septic shock that will hopefully translate into improved outcomes for the critically ill patient. The impact of these guidelines will be formally tested and guidelines updated annually, and even more rapidly when some important new knowledge becomes available.

New treatment strategies for severe sepsis and septic shock

PURPOSE OF REVIEW

Severe sepsis and septic shock are common causes of morbidity and mortality in critically ill patients. The complexities of the septic cascade continue to emerge and may identify new targets for innovative patient management. This review will highlight some of the recent advances in our management of the patient with sepsis.

RECENT FINDINGS

The early administration of adequate antibiotic therapy, effective source control, and goal-directed hemodynamic resuscitation are the cornerstone of successful management. Prevention of the complications of critical illness and maintenance of normal glucose levels are also important elements of effective management. In patients with vasopressor-dependent septic shock, evaluation for inadequate cortisol response and the provision of physiologic doses of replacement steroids for those found to be deficient may result in improved survival. Administration of drotrecogin alfa (activated), (activated protein C) has been shown to improve survival in patients with severe sepsis and septic shock who have a high risk of mortality. Because of its anticoagulant properties, caution must be exercised with the use of activated protein C in those patients who meet the contraindications for its use or who have risk factors for increased bleeding complications.

SUMMARY

Significant advances have been made in our understanding of the septic cascade and our ability to manage patients with severe sepsis and septic shock. Despite these advances, significant morbidity and mortality continue. In addition, there is also considerable impact on the financial and overall function of the patient.

Metabolic alterations in sepsis and vasoactive drug-related metabolic effects

The main clinical characteristics of sepsis and septic shock are derangements of cardiocirculatory and respiratory function. Additionally, profound alterations in metabolic pathways occur leading to hypermetabolism, enhanced energy expenditure, and insulin resistance. The clinical hallmarks are hyperglycemia, hyperlactatemia, and enhanced protein catabolism. These metabolic alterations are even more pronounced during sepsis as a result of cytokine release and subsequent induction of inflammatory pathways. Increased oxygen demands from mitochondrial oxygen utilization and oxygen consumption related to oxygen radical formation may contribute to hypermetabolism. In addition, mitochondrial dysfunction with impaired cellular respiration may be present. Mainstay therapeutic interventions for hemodynamic stabilization are adequate volume resuscitation and vasoactive agents, which, however, have additional impact on metabolic activity. Therefore, beyond hemodynamic effects, specific drug-related metabolic alterations need to be considered for optimal treatment during sepsis. This review gives an overview of the typical metabolic alterations during sepsis and septic shock and highlights the impact of vasoactive therapy on metabolism.