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.

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.

Use of methylene blue in patients with refractory septic shock: impact on hemodynamics and gas exchange.

PURPOSE: The purpose of this study was to assess the acute effects of methylene blue, an inhibitor of nitric oxide synthesis, on hemodynamics and gas exchange in patients with refractory septic shock in a prospective clinical trial at medical and surgical intensive care units in a tertiary university hospital. PATIENTS AND METHODS: Prospective, sequential study of 10 consecutive patients admitted with severe septic shock of diverse causes and unable to achieve an adequate arterial pressure despite the use of at least two vasoactive drugs. Six of them also developed acute lung injury. All received 1 mg/kg intravenous bolus of methylene blue. Hemodynamic and respiratory parameters were measured at baseline and at 30, 60, 120, and 180 minutes after the bolus injection. RESULTS: Systolic, diastolic, mean arterial blood pressure, and systemic vascular resistance increased significantly in all patients, whereas no significant changes were observed in cardiac output, oxygen consumption, or oxygen extraction ratio. Gas exchange remained unaffected in patients with acute lung injury. CONCLUSIONS: Methylene blue had an acute vasopressor effect in patients with refractory septic shock, and it was not deleterious on respiratory function.

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.

[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.

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.

[Aseptic meningitis following spinal anesthesia. Report of a case]. / Meningitis aséptica pos anestesia espinal. Caso clínico.

Aseptic meningitis after lumbar puncture and spinal anesthesia is a rare but serious complication, whose acute onset and clinical symptoms mimic septic meningitis. A 33 year old woman presented this complication 5 h after an uneventful cesarean section under subarachnoid blockade. Though lumbar puncture revealed pleocytosis with negative Gram stains and cultures, she was treated with antibiotics and made a full recovery. The clinical picture, differential diagnosis and value of early lumbar puncture are discussed. The successful use of midazolam to treat psychomotor agitation in this patient is also reported.

[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.

[Morphine infusion for postoperative pain management in patients who have undergone upper abdominal surgery]. / Infusión de morfina para el manejo del dolor postoperatorio en pacientes sometidos a cirugía abdominal alta.

We compared the efficacy and side effects of postoperative continuous infusions versus intermittent intravenous on-demand morphine, with or without the addition of clonixin. Eighty five healthy patients, aged 18 to 65 years, scheduled for elective cholecystectomy, were prospectively randomized: Group 1 (n = 22) received morphine 2.5 mg i.v. on-demand; group 2 (n = 22) received a clonixin 400 mg/day i.v. infusion; group 3 (n = 19) a morphine 0.4 mg/kg/day i.v. infusion; and group 4 (n = 22) received a clonixin 400 mg/day plus a morphine 0.4 mg/kg/day i.v. infusion. Groups 2, 3 and 4 also received, on-demand, 2.5 mg i.v. bolus doses of morphine. A blind observer recorder analogue and descriptive pain scores, respiratory rates and side-effects for 72 hours postoperatively. Groups with morphine infusions had less overall pain scores for the first day when compared with intermittent dosing (p < 0.05); these groups also had less pain during the night (p = 0.0016) and required less additional morphine (p < 0.0001). Side-effects were similar and no cases of heavy sedation or respiratory depression were observed. We conclude that a morphine 0.4 mg/kg/day infusion is a safe and effective alternative to on demand dosing in healthy patients after elective cholecystectomy, achieving better analgesia without increasing side-effects. Clonixin 400 mg/day seems to add no significant benefits.

Benzodiazepine premedication causes hypoxemia during spinal anesthesia in geriatric patients.

BACKGROUND AND OBJECTIVES: The use of sedatives during regional anesthesia can lead to life-threatening hypoxemia. Older patients particularly are prone to enhanced effects of these drugs. We studies whether oral premedication with benzodiazepines produced hypoxemia during spinal anesthesia in elderly patients. METHODS: In a prospective, double-blind, and randomized study, we evaluated the effect of oral benzodiazepine premedication on the incidence of hypoxemia measured by pulse oximetry (arterial oxygen saturation less than 90% for 30 seconds or longer) during surgery under spinal anesthesia in 80 geriatric patients divided into four equal groups: 1, control, no premedication; 2, 1 mg flunitrazepam; 3, 1 mg lorazepam; and 4, 7.5 mg midazolam. RESULTS: The incidence of hypoxemia in the four groups was: 1, 15%; 2, 45%; 3, 20%; and 4, 60% (p = 0.0078); overall incidence was 42% in premedicated patients versus 15% in unpremedicated controls (p = 0.0304). Seventy-four percent of patients who presented drowsiness and anesthetic level above T7 had desaturation compared to only 7% of those who were awake and had lower level (p less than 0.0005). No association between hypoxemia and other factors (age, weight, ASA physical status, and position during surgery) was found. All the episodes of desaturation were easily corrected with low supplemental oxygen concentrations. CONCLUSIONS: Premedication with oral benzodiazepines may produce hypoxemia during spinal anesthesia in elderly patients. Lorazepam appeared safer than flunitrazepam and midazolam. Monitoring of arterial blood oxygen saturation and/or supplemental oxygen is mandatory in geriatric patients with high spinal anesthetic level and/or drowsiness during surgery.

[Extracorporeal respiratory assistance. Experience in the treatment of severe acute respiratory failure]. / Apoyo respiratorio extracorpóreo: experiencia en el tratamiento de la insuficiencia respiratoria aguda severa.

Acute respiratory distress syndrome (ARDS) secondary to systemic injury has a high mortality. Symptomatic treatment with mechanical ventilation, PEEP and high levels of inspired oxygen is effective for most of the patients. When ventilatory support fails in reversing hypoxemia, extracorporeal respiratory assistance has been advocated as a temporary treatment until lung repair occurs. We described our experience in eleven patients (9M, 2F, 41 +/- 16 yo) with severe ARDS refractory to conventional treatment and expected to die if not assisted with extracorporeal oxygenation. All patients required invasive monitoring; seven needed continuous renal therapy because of concurrent renal failure. Venous-venous percutaneous cannulation and systemic anticoagulation were performed and extracorporeal oxygenation and CO2 removal started with blood pump flows of 20 to 30% of patient cardiac output. Improved oxygenation and decreased CO2 levels were immediately observed in 10/11 patients. One patient failed to have reversal of hypoxemia because recirculation and died shortly after initiation of extracorporeal therapy. Plasma leak syndrome and bleeding were observed in 3 and 2 patients respectively. Extracorporeal assistance was maintained for 52 +/- 34 h (19-134). Five (45%) patients were weaned off the pump and two (18%) survived and were discharged. Despite the high cost, extracorporeal respiratory assistance, when applied to selected patients, can reverse hypoxia and may save some previously unsalvagable patients, allowing them to return to a normal life.

[Headache following spinal puncture: treatment with epidural blood patch in a 7-year-old patient]. / Cefalea postpunción lumbar: tratamiento con parche de sangre peridural en una paciente de 7 años.

Lumbar puncture is frequently used for diagnostic and therapeutic purposes in children. Theoretically, this group of patients should have high rates of post lumbar puncture headache. However, the scant available literature points to a surprisingly low incidence and an apparently mild course. We present a 7 year-old patient with a severe post lumbar puncture headache successfully treated with an epidural blood patch. To our knowledge, this has not been reported in children younger than 10 years. We believe this procedure should be considered in pediatric patients with post lumbar puncture headache.