Célica L. Irrazábal

Is a Strategy Based on Routine Endotracheal Cultures the Best Way to Prescribe Antibiotics in Ventilator-Associated Pneumonia?

OBJECTIVES The objectives of this study were to evaluate if a strategy based on routine endotracheal aspirate (ETA) cultures is better than using the American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines to prescribe antimicrobials in ventilator-associated pneumonia (VAP). METHODS This was a prospective, observational, cohort study conducted in a 15-bed ICU and comprising 283 patients who were mechanically ventilated for ≥48 h. Interventions included twice-weekly ETA; BAL culture was done if VAP was suspected. BAL (collected at the time of VAP) plus ETA cultures (collected≤7 days before VAP) (n=146 different pairs) were defined. We compared two models of 10 days of empirical antimicrobials (ETA-based vs ATS/IDSA guidelines-based strategies), analyzing their impact on appropriateness of therapy and total antimicrobial-days, using the BAL result as the standard for comparison. RESULTS Complete ETA and BAL culture concordance (identical pathogens or negative result) occurred in 52 pairs; discordance (false positive or false negative) in 67, and partial concordance in two. ETA predicted the etiology in 62.4% of all pairs, in 74.0% of pairs if ETA was performed≤2 days before BAL, and in 46.2% of pairs if ETA was performed 3 to 7 days before BAL (P=.016). Strategies based on the ATS/IDSA guidelines and on ETA results led to appropriate therapy in 97.9% and 77.4% of pairs, respectively (P<.001). The numbers of antimicrobial-days were 1,942 and 1,557 for therapies based on ATS/IDSA guidelines and ETA results, respectively (P<.001). CONCLUSIONS The ATS/IDSA guidelines-based approach was more accurate than the ETA-based strategy for prescribing appropriate, initial, empirical antibiotics in VAP, unless a sample was available≤2 days of the onset of VAP. The ETA-based strategy led to fewer days on prescribed antimicrobials.

Neutropenia and the development of the systemic inflammatory response syndrome

Abstract Objective. To determine outcome and natural course of systemic inflammatory response syndrome (SIRS) stages in adult febrile neutropenic patients. Design and setting. Retrospective cohort study in the medicine department and intensive care unit of a university hospital. Patients. Adults with cancer-related neutropenia and community-acquired fever. Measurements and results. Patients were classified on admission according to SIRS parameters, tumor type, and degree of neutropenia. Records of clinical and laboratory data during hospitalization were reviewed. Univariate and logistic regression analyses were performed. Seventy-nine events in 62 patients were analyzed. Overall mortality rate was 20.2% (16/79). Mortality increased as SIRS stage worsened on admission. No patients with stage 2 SIRS died (neutropenia and fever alone) but 11.1% of patients with SIRS 3, 43.4% with SIRS 4, 66.6% with sepsis induced hypotension, and 90% with septic shock. SIRS stage on admission was an independent predictor of death and was related directly to rate of progression to shock, i.e., none of the patients with SIRS 2, 2.7%(1/36) of those with SIRS 3, and 30.4% (7/23) of those admitted with SIRS 4. Conclusions. Mortality and progression to septic shock increased as more SIRS criteria were met on admission. SIRS stages could serve as a risk-assessing model in febrile neutropenic patients.

Interrelationship between oxygen‐related variables in patients with acute myocardial infarction: an interpretative review

The high mortality rate of cardiogenic shock in acute myocardial infarction (AMI) implies that debate over the correct haemodynamic management is still unresolved. The purpose of this review is to re‐evaluate the reciprocal relationships between oxygen‐related variables and response to treatment in a large number of patients with AMI. A MEDLINE search of reports published between 1970 and 2008 was performed. Twelve clinical reports including 453 patients with AMI and 989 sets of oxygen delivery and oxygen consumption expressed in ml min−1 m−2 and oxygen extraction ratio were selected. While processing this data, we found an early down‐regulation in oxygen demand linked to a decrease in oxygen supply. This mechanism is also supported in some studies by a critically low oxygen uptake that was not associated with lactic acidosis.

Assessing shock resuscitation strtegies by oxygen debt repayment.

To the Editor: Barbee et al. (1) examined the oxygen supplydelivery in relation to the acquisition of an oxygen debt and its relevance to the current understanding of shock and resuscitation. Oxygen debt is defined as the integral difference between the prehemorrhage and pretrauma resting Bnormal[ oxygen consumption (V̇O2) with the level measured at a given time during the shock period. However, extrapolation of this experimental concept to the clinical setting is questionable because most patients often slip slowly into shock with clinical evidence of a low cardiac output, before the development of hypotension and metabolic (lactic) acidosis. Downregulation of metabolic requirements during the early phase of shockVnot associated with anaerobic metabolismVindicates that these patients are not acquiring an oxygen debt (2). A lowering in V̇O2 has been reported in cardiac ischemic syndromes with low cardiac output (3). We recently treated a 64-year-old woman who was transfused before and during the emergency surgical repair of a spleen artery bleeding aneurysm. She was admitted to the intensive care unit in shock, requiring hemodynamic monitoring and management with transfusions, vasoactive agents, and supportive care according to her hemodynamic status. At admission (point A), she had a core temperature of 35.8-C; oxygen delivery index (IDO2), 157 mL min j1 m; oxygen consumption index (IV̇O2), 86 mL I min j1 I m; lactate, 7.2 mmol I L; and base excess (BE), j14 mEq/L. Evolution of these data during a 72-h period are shown for IDO2 and oxygen extraction ratio in the IV̇O2 tendency line depicted in the nomogram of isoconsumption curves (Fig. 1). Clinical improvement was progressively accomplished, associated to correlative (R = 0.94) normalization of both lactate and BE levels (point B: at 72 h). IV̇O2 was steadily maintained at less than 100 mL I min I m as the highly significant tendency line shows, associated with a sharp decrease in oxygen extraction ratio and an increase in IDO2, although without attaining normality. Despite the initial evidence of anaerobic metabolism, the oxygen debt repayment phase was missing during the uneventful recovery period, and the calculation of an oxygen debt in this setting would have been clearly misleading. Downregulation of oxygen demand reflects a metabolic cellular adaptive response to the challenge of a diminished supply, moderating or avoiding the development of an oxygen deficit. Singer et al. (4) hypothesized that the regulated induction of a hypometabolic state, resembling hibernation, may protect the cells from dying, enhancing the chances of recovery of organ function should the patient survive. Lowering oxygen demand may be an important underlying mechanism in many clinical situations with progressive decreases in DO2 and could represent a feasible explanation for different findings, for example, the lack of correlation between IDO2 and lactate levels reported in patients with sepsis and acute myocardial infarction (5). It could also explain why incomplete blood volume replacement in hypotensive resuscitation appears with promising results in this innovative resuscitation concept.