Recomendación Clínica: "Recomendaciones para el manejo de pacientes con COVID-19 con indicación terapéutica de ventilación mecánica que eventualmente son conectados a máquinas de anestesia" / Recommendations for patient management with COVID-19 with therapeutic indication mechanical ventilation that eventually are connected to anesthesia machines

La pandemia de COVID-19 producida por SARS-CoV-2 actualmente en curso anticipa una gran demanda por ventiladores mecánicos (VM), ya que un porcentaje relevante de los contagiados cae rápidamente en insuficiencia respiratoria y requiere de cuidados intensivos. Anticipándose a ese exceso de demanda y considerando que es muy probable que el número actual de ventiladores mecánicos en las unidades de cuidados intensivos (UCI) sean insuficientes, se ha solicitado a la SACH un informe técnico en relación al uso de las máquinas de anestesia como VM.

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.

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.

[Limitations of the technique to determine hydrogen peroxide levels in exhaled breath condensate from patients with adult respiratory distress syndrome]. / Limitaciones de la técnica de determinación de peróxido de hidrógeno en el condensado del aire espirado de pacientes con síndrome de distrés respiratorio del adulto.

OBJECTIVE: Exhaled breath condensate represents an alternative to bronchoalveolar lavage for the analysis of markers of inflammation and oxidative stress in patients with adult respiratory distress syndrome (ARDS). However, analysis of hydrogen peroxide (H2O2) yields variable results that do not correlate with severity of the clinical presentation. In an attempt to explain this variability, the aim of the present study was to assess the possible limitations of the most commonly used technique for analyzing H2O2 in breath condensate. PATIENTS AND METHODS: H2O2 levels were analyzed using the Gallati technique (linear range between 0.3 and 10 microM, r=0.99; P<.05) in serial samples of condensate taken from the expiratory tube of a mechanical ventilator in 6 patients with ARDS. RESULTS: The volume of condensate obtained correlated to minute ventilation (r=0.96; P<.05). In 11 out of 23 samples, a spectrophotometer reading was obtained at 450 nm despite the absence of the characteristic color of the reaction and in some of these samples a spontaneous reading was obtained that was indicative of contamination. The absorbance spectrum of these samples did not contain the characteristic peak for H2O2 at 450 nm and pretreatment of some samples with catalase did not affect the absorbance at 450 nm. CONCLUSIONS: The spectrophotometric method commonly used to measure H2O2 levels in breath condensate lacks specificity in ARDS due to the presence of variable levels of contaminants in the samples, which lead to false positives.

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.

[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.

[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.

Utilidad clínica del diagnóstico serológico de TBC por un test de ELISA / Clinical useful of the serological diagnosis of TBC by an ELISA test

La tuberculosis es una enfermedad de alta prevalencia. Sería de gran utilidad disponer de un método serológico principalmente en los casos que son positivos sólo por cultivo que demora 30 a 60 días. El inconveniente de la serología radica en la interpretación de los resultados, por lo que se requiere una cuidadosa evaluación de la utilidad clínica del test en un área determinada. Con el objetivo de implementar y determinar la utilidad clínica del diagnóstico serológico de TBC, se estudiaron los sueros de 101 pacientes divididos en 4 grupos; grupo 1: 26 controles sanos, grupo 2: 25 pacientes con patología pulmonar no TBC, grupo 3: 27 tuberculosos baciloscopia (+) y grupo 4: 2 tuberculosos sólo cultivo (+). Se determinó IgG, IgM y IgA anti antígeno A60 por un ELISA indirecto cenocial. Se calculó para cada suero la sumatoria de las 3 clases de inmunoglobulinas y se estableció un punto de corte de 0,45 absorvancia. La sensibilidad para grupo 4 fue de 78 por ciento y la específidad para grupo 2 fue de 88 por ciento. Con estos resultados la aplicación del test como screening de TBC resulta no recomendable con un alto número de falsos (+) que lleva a tratamientos prolongados e innecesarios. En cambio, el test sería de gran utilidad si se emplea en pacientes hospitalizados, en los que se descarten patologías de diagnóstico diferencial de TBC (cáncer, neumonías, cavitarias, etc). A medida que se va descartando otras patologías, (probabilidad pre-test) va aumentando con lo cual el valor predictivo positivo del examen mejora significativamente: si la probabilidad pre-test es 0,3, el valor predictivo positivo es de 74 por ciento y si la probabilidad pre-test es de 0,7, el valor predictivo positivo aumenta a 94 por ciento. En conclusión, el test de ELISA anti-antígeno A60 sería de gran utilidad como otro elemento de apoyo en pacientes con alta probabilidad clínica de TBC y microbiología negativa