High PEEP levels are associated with overdistension and tidal recruitment/derecruitment in ARDS patients.

BACKGROUND: Positive end-expiratory pressure (PEEP) improves gas exchange and respiratory mechanics, and it may decrease tissue injury and inflammation. The mechanisms of this protective effect are not fully elucidated. Our aim was to determine the intrinsic effects of moderate and higher levels of PEEP on tidal recruitment/derecruitment, hyperinflation, and lung mechanics, in patients with acute respiratory distress syndrome (ARDS). METHODS: Nine patients with ARDS of mainly pulmonary origin were ventilated sequential and randomly using two levels of PEEP: 9 and 15 cmH2 O, and studied with dynamic computed tomography at a fix transversal lung region. Tidal recruitment/derecruitment and hyperinflation were determined as non-aerated tissue and hyperinflated tissue variation between inspiration and expiration, expressed as percentage of total weight. We also assessed the maximal amount of non-aerated and hyperinflated tissue weight. RESULTS: PEEP 15 cmH2 O was associated with decrease in non-aerated tissue in all the patients (P < 0.01). However, PEEP 15 cmH2 O did not decrease tidal recruitment/derecruitment compared to PEEP 9 cmH2 O (P = 1). In addition, PEEP 15 cmH2 O markedly increased maximal hyperinflation (P < 0.01) and tidal hyperinflation (P < 0.05). Lung compliance decreased with PEEP 15 cmH2 O (P < 0.001). CONCLUSION: In this series of patients with ARDS of mainly pulmonary origin, application of high levels of PEEP did not decrease tidal recruitment/derecruitment, but instead consistently increased tidal and maximal hyperinflation.

Tidal volume is a major determinant of cyclic recruitment-derecruitment in acute respiratory distress syndrome.

BACKGROUND: Overdistension and cyclic recruitment-derecruitment contribute to ventilator-induced lung injury. High tidal volumes are thought to increase mortality mainly by inducing overdistension. However, experimental evidence suggests that tidal volume (VT) may also influence cyclic recruitment-derecruitment. Our main goal was to determine whether high tidal volumes increase cyclic recruitment-derecruitment in acute respiratory distress syndrome (ARDS) patients, as measured by dynamic computed tomography (CT). METHODS: We studied 9 ARDS patients with diffuse attenuations on CT who underwent a protocol including 2 ventilatory modes: (a) VT 6 mL/kg, respiratory rate 30/min, PEEP 9 cmH2O, (b) VT 12 mL/kg, respiratory rate 15/min, PEEP 9 cmH2O. A dynamic computed tomography of 8 seconds on a fixed transverse region was performed during each ventilator mode. Cyclic recruitment-derecruitment was determined as non-aerated tissue variation between inspiration and expiration and was expressed as % of lung tissue weight. RESULTS: VT 12 mL/kg exhibited less non-aerated tissue at expiration compared to VT 6 ml/kg (40.15 [35.94-56.00] and 45.31 [37.95-59.32], respectively, P<0.05). However, VT 12 ml/kg increased cyclic recruitment-derecruitment compared to VT 6 mL/kg (7.32 [6.58-9.29] mL/kg vs. 4.51 [3.42-5.75] mL/kg, P<0.01). Tidal hyperinflation was also larger at VT 12 mL/kg (0.55 [0.27-2.24] vs. 0.24 [0.18-0.83], P<0.01). CONCLUSION: High tidal volume is a major determinant of cyclic recruitment-derecruitment in ARDS patients with diffuse attenuations.

[Confusion Assessment Method for diagnosing delirium in ICU patients (CAM-ICU): cultural adaptation and validation of the Spanish version]. / Método para la evaluación de la confusión en la unidad de cuidados intensivos para el diagnóstico de delírium: adaptación cultural y validación de la versión en idioma español.

OBJECTIVE: To adapt the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) for the diagnosis of delirium to the language and culture of Spain and to validate the adapted version. DESIGN: Population validation. SETTING: Intensive care units in a 600-bed university hospital. PATIENTS: We studied 29 critical patients undergoing mechanical ventilation. Mean age was 70 years (range 58-77 years), mean APACHE II score 16 (range 13-21), and mean SOFA score 7 (range 4-8). INTERVENTION: Two independent operators applied the Spanish version of the CAM-ICU and a psychiatrist applied the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition-Revised (DSM IV TR). MAIN OUTCOME VARIABLES: Concordance (kappa index), internal consistency (Cronbach's alpha), and validity (sensitivity and specificity) of the Spanish version of the CAM-ICU were compared to the DSM IV TR, which is considered the current gold standard. RESULTS: The translation and cultural adaptation was carried out in accordance with current international guidelines. A total of 65 assessments were performed in 29 patients. The interobserver concordance was high: kappa statistic 0.91 (95% CI: 0.86-0.96). The internal consistence was adequate: Cronbach's alpha=0.84 (unilateral 95% CI: 0.77). For observer A (a physician), the sensitivity of the Spanish version of the CAM-ICU was 80% and the specificity was 96%. For observer B, (a nurse) the sensitivity was 83% and the specificity was 96%. CONCLUSIONS: The Spanish version of the CAM-ICU is a valid, reliable, and reproducible instrument that can be satisfactorily applied to diagnose delirium in Spanish-speaking ICU patients.

[Characteristics and impact of sedation, analgesia, and neuromuscular blockage in critical patients undergoing prolonged mechanical ventilation]. / Características e impacto de la sedación, la analgesia y el bloqueo neuromuscular en los pacientes críticos que recibieron ventilación mecánica prolongada.

AIM: To describe use of sedatives, analgesics, and neuromuscular blockers (NMB) in patients undergoing long-term mechanical ventilation and to assess factors associated with their use and their association with mortality at 28 days. DESIGN: Prospective observational multicenter cohort study. SETTING: Thirteen intensive care units (ICU) in Chile. PATIENTS: Patients undergoing mechanical ventilation for more than 48h. We excluded patients with neurological disorders, cirrhosis of the liver, chronic renal failure, suspected drug addiction, and early no resuscitation orders. INTERVENTION: None. MAIN MEASUREMENTS: Proportion of use and dosage of sedatives, analgesics, and NMB. Level of sedation observed (SAS). Variables associated with the Sedation Agitation Scale (SAS), use of sedatives, analgesics, and NMB. Multivariate logistic regression of variables associated to mortality at 28 days. RESULTS: A total of 155 patients participated (60+/-18 years, 57% male, SOFA 7 [6-10], APACHE II 18 [15-22], 63% with sepsis, and 47% with acute lung injury/adult respiratory distress syndrome. The drugs most frequently used were midazolam (85%, 4 [1.9-6.8]mg/hr) and fentanyl (81%, 76 [39-140]microg/hr). NMB were administered at least 1 day in 30% of patients. SAS score was 1 or 2 in 55% of patients. There was an association between NMB use and mortality at 28 days, but it was not consistent in all the models of NMB evaluated. CONCLUSIONS: Sedatives were frequently employed and deep sedation was common. Midazolam and fentanyl were the most frequently administered drugs. The use of NMB might be independently associated to greater mortality.

An evidence-based resuscitation algorithm applied from the emergency room to the ICU improves survival of severe septic shock.

BACKGROUND: Septic shock is highly lethal. We recently implemented an algorithm (advanced resuscitation algorithm for septic shock, ARAS 1) with a global survival of 67%, but with a very high mortality (72%) in severe cases [norepinephrine (NE) requirements >0.3 microg/kg/min for mean arterial pressure > or =70 mmHg]. As new therapies with different levels of evidence were proposed [steroids, drotrecogin alpha, high-volume hemofiltration (HVHF)], we incorporated them according to severity (NE requirements; algorithm ARAS-2), and constructed a multidisciplinary team to manage these patients from the emergency room (ER) to the ICU. The aim of this study was to compare the outcome of severe septic shock patients under both protocols. METHODS: Adult patients with severe septic shock were enrolled consecutively and managed prospectively with ARAS-1 (1999-2001), and ARAS-2 (2002-05). ARAS-2 incorporates HVHF for intractable shock. RESULTS: Thirty-three patients were managed with each protocol, without statistical differences in baseline demographics, APACHE II (22.2 vs 23.8), SOFA (11.4 vs 12.7) and NE peak levels (0.62 vs 0.8 microg/kg/min). The 28-day mortality and epinephrine use were higher with ARAS-1 (72.7% vs 48.5%; 87.9% vs 18.2 %); and low-dose steroids (35.9% vs 72.7%), drotrecogin (0 vs 15 %) and HVHF use (3.0% vs 39.4%) were higher for ARAS-2 (P<0.05 for all). CONCLUSION: Management of severe septic shock with a multidisciplinary team and an updated protocol (according to the best current evidence), with precise entry criteria for every intervention at different stages of severity, may improve survival in these patients. Multidisciplinary management, rationalization of the use of vasoactives and rescue therapy based on HVHF instead of epinephrine may have contributed to these RESULTS: Management of severe septic shock with these kinds of algorithms is feasible and should be encouraged.

[Prognosis for acute exacerbation of chronic obstructive pulmonary disease in mechanically ventilated patients]. / Pronóstico de los enfermos con enfermedad pulmonar obstructiva crónica reagudizada que precisan ventilación mecánica.

OBJECTIVE: To determine the variables associated with prognosis for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in mechanically ventilated patients. DESIGN: Prospective cohort study with retrospective analysis. LOCATION: 361 Intensive Care Units (ICU) in 20 countries. PATIENTS AND METHODS: There were included in the study 522 patients who required mechanical ventilation for more than 12 hours due to an acute exacerbation of chronic obstructive pulmonary disease (AECOPD). In order to determine those variables associated with mortality, there was performed a recursive partition analysis in which the following variables were included: demographics, arterial blood gas prior to intubation, complications arising during mechanical ventilation (barotrauma, acute respiratory distress syndrome, ventilator-associated pneumonia, sepsis), organ dysfunction (cardiovascular, renal, liver, coagulation) and duration of ventilatory support. INTERVENTIONS: None. VARIABLES OF PRIME IMPORTANCE: ICU mortality. RESULTS: ICU and hospital mortality rates were 22% and 30%, respectively. Variables associated with mortality were cardiovascular dysfunction, renal dysfunction and duration of ventilatory support > 18 days. Median durations were as follows: mechanical ventilatory support, 4 days (P25: 2, P75: 6); weaning from ventilatory support, 2 days (P25: 1, P75: 5); stay in intensive care unit, 8 days (P25: 5, P75: 13); stay in hospital, 17 days (P25: 10, P75: 27). CONCLUSIONS: Mortality in the studied cohort of patients with AECOPD was associated with cardiovascular dysfunction, renal dysfunction and prolonged mechanical support.

[Preliminary experience with dexmedetomidine treatment of confusional state and hyperadrenergic states at an intensive care unit]. / Experiencia preliminar del tratamiento con dexmedetomidina del estado confusional e hiperadrenergia en la unidad de cuidados intensivos.

Delirium (confusion) is an acute, reversible and fluctuating compromise of awareness and cognitive function, a state that can increase morbidity and mortality. We describe four patients with delirium associated with agitation and hyperadrenergic states refractory to haloperidol but responsive to dexmedetomidine.

Influence of polymeric enteral nutrition supplemented with different doses of glutamine on gut permeability in critically ill patients.

OBJECTIVES: To evaluate the effect of glutamine-supplemented polymeric enteral formulas on the recovery of gut-permeability abnormalities in critically ill patients. METHODS: Twenty-three patients were randomized to receive a conventional casein-based enteral formula (ADN), ADN plus glutamine in a dose of 0.15 g x kg(-1) x d(-1) or ADN plus 0.30 g x kg(-1) x d(-1) of glutamine for 8 d. The lactulose mannitol permeability test (L/M) was performed at baseline and at the end of the study. Nineteen healthy volunteers served as controls for the L/M test. RESULTS: An increase in permeability compared with control subjects was observed in patients at baseline (mean +/- standard error of the mean; L/M ratio: 0.11 +/- 0.03 and 0.025 +/- 0.004, respectively; P < 0.02). The L/M ratio improved after the period of enteral nutrition as a whole (initial L/M: 0.11 +/- 0.03, final L/M: 0.061 +/- 0.01; P < 0.03), but no difference was found between groups. CONCLUSIONS: Even though polymeric enteral nutrition was associated with a significant improvement in the L/M ratio, glutamine supplementation did not show a specific influence in improving recovery of gut permeability in critically ill patients.

[Suprahepatic vein catheterization in 4 cases of severe septic shock]. / Cateterización venosa suprahepática en cuatro casos de shock séptico severo.

Splanchnic hypoperfusion, with pathogenic implications for multiple organ failure, can occur during septic shock. We report four patients with septic shock in whom regional hepatosplenic splanchnic perfusion was monitored through suprahepatic vein catheterization and gastric tonometry. Suprahepatic lactate and oxygen saturation showed splanchnic hypoperfusion in all patients. These parameters improved only in the patient that survived. Gastric tonometry was more inconsistent. We conclude that suprahepatic vein catheterization could have a role in the management of septic shock.

How is mechanical ventilation employed in the intensive care unit? An international utilization review.

A 1-d point-prevalence study was performed with the aim of describing the characteristics of conventional mechanical ventilation in intensive care units ICUs from North America, South America, Spain, and Portugal. The study involved 412 medical-surgical ICUs and 1,638 patients receiving mechanical ventilation at the moment of the study. The main outcome measures were characterization of the indications for initiation of mechanical ventilation, the artificial airways used to deliver mechanical ventilation, the ventilator modes and settings, and the methods of weaning. The median age of the study patients was 61 yr, and the median duration of mechanical ventilation at the time of the study was 7 d. Common indications for the initiation of mechanical ventilation included acute respiratory failure (66%), acute exacerbation of chronic obstructive pulmonary disease (13%), coma (10%), and neuromuscular disorders (10%). Mechanical ventilation was delivered via an endotracheal tube in 75% of patients, a tracheostomy in 24%, and a facial mask in 1%. Ventilator modes consisted of assist/control ventilation in 47% of patients and 46% were ventilated with synchronized intermittent mandatory ventilation, pressure support, or the combination of both. The median tidal volume setting was 9 ml/kg in patients receiving assist/control and the median setting of pressure support was 18 cm H(2)O. Positive end-expiratory pressure was not employed in 31% of patients. Method of weaning varied considerably from country to country, and even within a country several methods were in use. We conclude that the primary indications for mechanical ventilation and the ventilator settings were remarkably similar across countries, but the selection of modes of mechanical ventilation and methods of weaning varied considerably from country to country.

[Use of amphotericin B in lipid emulsions: does it prevent its toxicity in critically ill patients?]. / Uso de anfotericina B en mezcla lipídica: previene la toxicidad de la droga en pacientes críticos?

BACKGROUND: Amphotericin B is efficacious for the treatment of systemic candidiasis, however it has potentially serious toxic effects. Administration as lipid emulsions has been advocated to decrease its toxicity. AIM: To compare the safety and tolerance of amphotericin B administered as lipid emulsion or dissolved in dextrose in water. PATIENTS AND METHODS: Forty five patients with confirmed or highly suspected systemic candidiasis were studied. Between January 1996 and June 1997 amphotericin B was administered in dextrose in water to 17 patients (group 1). Between July 1997 and December 1998, the drug was delivered in lipid emulsions (Intralipid, group 2). Clinical and laboratory parameters (serum creatinine, urea nitrogen and potassium), were assessed daily. RESULTS: Both treatment groups were clinically comparable and had the same survival. Accumulative amphotericin B dose administered was 343.2 +/- 197 and 414.6 +/- 518 mg respectively. Hypokalemia was more frequent in group 2 (52 and 25% respectively, p < 0.05). There were no differences in the outcome of renal function or other adverse reactions. CONCLUSIONS: Administration of amphotericin B as lipid emulsions did not reduce its toxicity in critical patients (Rev Méd Chile 2000; 128: 1101-07).

[Transcranial cytokine gradient and intestinal permeability in acute severe brain injury]. / Gradiente transcraneana de citoquinas y permeabilidad intestinal en la injuria cerebral aguda severa.

BACKGROUND: Acute brain injury is associated with a bimodal hypermetabolic state probably caused by cytokine secretion and high hormone and catecholamine concentrations. In a first stage, the brain would produce these substances and afterwards, another production source, most probably the splanchnic territory, would perpetuate the hypermetabolic state. AIM: To investigate the cytokine production source and to assess intestinal permeability in acute brain injury in the absence of cerebral ischemia and systemic oxygen deficit. PATIENTS AND METHODS: Arterial systemic and cerebral venous bulbar interleukin 1 beta and interleukin 6 levels were measured during the first seven days of evolution in 15 patients with acute brain injury. Serum lactate, the oxygen/lactate ratio, gastric intramucosal pH and intestinal permeability using the lactulose/mannitol test were also assessed in the same period. RESULTS: High arterial and venous interleukin 1 beta and interleukin 6 levels were detected. A positive gradient for interleukin 6 levels was detected throughout the study period with normal intramucosal pH, lactate and oxygen/lactate ratio. There was also an early impairment of intestinal permeability in these patients. CONCLUSIONS: High arterial and venous cytokine concentrations were detected in patients with acute brain injury. The positive gradient for interleukin 6 suggests a brain origin for this cytokine. Intestinal permeability is also altered in these patients.

[Acute effect of dobutamine and amrinone on hemodynamics and splanchnic perfusion in septic shock patients]. / Efecto agudo de dobutamina y amrinona sobre la hemodinamia y perfusión esplácnica de pacientes en shock séptico.

BACKGROUND: Vasoactive drugs used in the reanimation of septic patients, can modify splanchnic perfusion. AIM: To compare the effects of dobutamine and amrinone on gastric intramucosal pH (pHi), lactate levels and hemodynamics in surgical patients with compensated septic shock. PATIENTS AND METHODS: Fourteen postoperative patients with abdominal sepsis and compensated septic shock (pHi < 7.32 or lactate > 2.5 mmol/l) were studied in a prospective, randomized, unblinded study. Patients were randomized to receive (Group 1, n = 7) dobutamine at 5 micrograms/Kg/min or (Group 2, n = 7) amrinone at 5 micrograms/Kg/min. Hemodynamic data, arterial lactate and pHi were measured before and 30, 60 and 120 minutes after starting drug infusion. RESULTS: Both drugs were associated with a decrease in lactate levels. Dobutamine infusion, but not amrinone, increased gastric pHi, as well as cardiac index and oxygen delivery. CONCLUSIONS: An improvement in gastric pHi associated with an increase in oxygen delivery, was observed with dobutamine. Amrinone showed no effect at the fixed, low dose used in the study.

[Ventilatory support in patients with acute disease of the central nervous system]. / Apoyo ventilatorio en pacientes con patología aguda del sistema nervioso central.

Patients with severe head injury are prone to pulmonary complications that result in hypoxemia or hypercarbia, which could worsen their neurological condition. A rational ventilatory approach requires a good knowledge of respiratory and neurological pathophysiology. Airway management is of prime importance in neurological patients. Prophylactic chronic hyperventilation in head trauma is no longer recommended since it could impair cerebral perfusion, although transient hypocarbia could be of benefit to some patients. The use of low or moderate positive and expiratory pressure levels apparently improves oxygenation without worsening intracranial pressure. Ventilatory management should be closely monitored and adjusted to hemodynamic, respiratory and neurological status to achieve a good outcome.

Gut mucosal atrophy after a short enteral fasting period in critically ill patients.

PURPOSE: The purpose of this study was to evaluate the presence of gut mucosal atrophy and changes in mucosal permeability in critically ill patients after a short fasting period. MATERIALS AND METHODS: Fifteen critically ill patients underwent a period of enteral fasting of at least 4 days (mean 7.8 days). We took the following measurements the day before initiating enteral nutrition: indirect calorimetry, serum albumin, prealbumin, and lymphocyte count. We also performed a duodenal endoscopic biopsy with histopathological and mucosal morphometric analysis including villus height and crypt depth. The lactulose-mannitol test was performed to assess gut permeability. A total of 28 healthy volunteers served as controls for duodenal biopsy or lactulose-mannitol test. Clinical data, such as length of fasting, severity score, and previous parenteral nutritional support, were recorded. RESULTS: We found gut mucosal atrophy, expressed as a decrease in villus height and crypt depth, in patients compared with controls. The patients also exhibited an abnormal lactulose-mannitol test. Morphometric changes did not correlate with permeability. Further, we found no correlation between the results of the lactulose-mannitol test and of mucosal morphometry with clinical data. CONCLUSIONS: We found that a short period of enteral fasting was associated with significant duodenal mucosal atrophy and abnormal gut permeability in critically ill patients.

Ondansetron and droperidol in the prevention of postoperative nausea and vomiting.

We have performed a prospective, randomized, double-blind clinical study to assess the efficacy of ondansetron, droperidol, or both, in preventing postoperative emesis. We studied 242 patients undergoing biliary or gynaecological surgery under general anaesthesia. Shortly before induction of anaesthesia, patients received: saline i.v. (group I, n = 62); droperidol 2.5 mg i.v. (group 2, n = 60); ondansetron 4 mg i.v. (group 3, n = 57); or droperidol 2.5 mg with ondansetron 4 mg i.v. (group 4, n = 63). Nausea occurred in 45%, 37%, 32% and 29% (P = 0.234) and vomiting in 23%, 17%, 9% and 5% (P = 0.016) of patients in groups 1, 2, 3 and 4, respectively, during the first 24 h. Groups 2 and 4 had greater sedation scores than group 1 during the first 3 h (P < 0.01). We conclude that both droperidol and ondansetron showed a significant antiemetic effect, ondansetron was not significantly better than droperidol, and the combination of droperidol and ondansetron was better than droperidol but no better than ondansetron alone.

[Systemic inflammatory response syndrome: is it comparable with severe sepsis?]. / Síndrome de respuesta inflamatoria sistémica severa: es comparable a la sepsis severa?

BACKGROUND: In 1992, a consensus conference defined the terms systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis and septic shock. Since then, numerous reports have validated the prognostic usefulness of these operative definitions. AIM: To evaluate if sepsis severity criteria, as defined by the Consensus Conference, can be applied to noninfectious SIRS. PATIENTS AND METHODS: Five hundred eighteen patients admitted to 5 intensive care units (ICU) from 4 hospitals were prospectively evaluated during a 3 months period. Patients that met at least one severity criteria were included. SIRS etiology, organ dysfunction and evolution were recorded in each patient. RESULTS: One hundred two patients were included: 79 with sepsis (group I) and 23 with noninfectious SIRS (group II). ICU and hospital mortality were comparable (43 and 48% in sepsis compared to 43 and 51% in non infectious SIRS). The most common sources of sepsis were pneumonia and peritonitis. Group II patients had a wide variety of diseases. ICU stay, APACHE score and number of organs with dysfunction were not different among groups. Only the incidence of renal dysfunction was higher in the septic group. CONCLUSIONS: The Consensus sepsis severity criteria can be applied to noninfectious SIRS, defining a population subset with similar high mortality and organ dysfunction incidence, although with greatly heterogeneous etiologies.