13CO2 recovery fraction in expired air of septic patients under mechanical ventilation

The continuous intravenous administration of isotopic bicarbonate (NaH13CO2) has been used for the determination of the retention of the 13CO2 fraction or the 13CO2 recovered in expired air. This determination is important for the calculation of substrate oxidation. The aim of the present study was to evaluate, in critically ill patients with sepsis under mechanical ventilation, the 13CO2 recovery fraction in expired air after continuous intravenous infusion of NaH13CO2 (3.8 µmol/kg diluted in 0.9% saline in ddH2O). A prospective study was conducted on 10 patients with septic shock between the second and fifth day of sepsis evolution (APACHE II, 25.9 ± 7.4). Initially, baseline CO2 was collected and indirect calorimetry was also performed. A primer of 5 mL NaH13CO2 was administered followed by continuous infusion of 5 mL/h for 6 h. Six CO2 production (VCO2) measurements (30 min each) were made with a portable metabolic cart connected to a respirator and hourly samples of expired air were obtained using a 750-mL gas collecting bag attached to the outlet of the respirator. 13CO2 enrichment in expired air was determined with a mass spectrometer. The patients presented a mean value of VCO2 of 182 ± 52 mL/min during the steady-state phase. The mean recovery fraction was 0.68 ± 0.06%, which is less than that reported in the literature (0.82 ± 0.03%). This suggests that the 13CO2 recovery fraction in septic patients following enteral feeding is incomplete, indicating retention of 13CO2 in the organism. The severity of septic shock in terms of the prognostic index APACHE II and the sepsis score was not associated with the 13CO2 recovery fraction in expired air.Pró-Reitoria de Pesquisa da Universidade de São Paulo (USP)(FAEPA) Fundação de Amparo ao Ensino, Pesquisa e AssistênciaFAPES

Circulatory shock syndrome

Circulatory shock is marked by critical reductions on tecidual perfusion, causing severe systemic alterations, impairing cellular and organic function, with a high mortality rate as result. The prompt diagnosis and therapeutics should be based on individual response, emphasizing ventilatory and hemodynamic support. The knowledge of physiopathology directs therapeutic decisions, since the objectives to be reached are based on physiopathology. Several recent therapies are being investigated on patients with circulatoty shock, such as fluid resuscitation, red cells bood substitutes, and therapies directed to mediators (cytokines, endotoxins, prostaglandins, leukotrienes, and platelet-activating factor).O choque circulatório é marcado por reduções críticas na perfusão tecidual, provocando alterações sistêmicas graves, com comprometimento da função celular e orgânica, com alto índice de mortalidade. O diagnóstico e a instituição de medidas terapêuticas devem ser precoces e baseados na resposta individual de cada paciente, dando-se ênfase ao suporte ventilatório e hemodinâmico. O conhecimento profundo da sua fisiopatologia norteia as decisões terapêuticas, uma vez que através dela se estabelecem objetivos a serem atingidos. Diversas condutas recentes estão sendo pesquisadas em pacientes com choque circulatório. Estas medidas incluem reposições volêmicas, simples, soluções substitutas de hemácias e terapias dirigidas aos mediadores (citoquinas, endotoxinas, prostaglandinas, leucotrienos e fator de ativação plaquetária)

Effect of heat and moisture exchangers on the prevention of ventilator-associated pneumonia in critically ill patients

Ventilator-associated pneumonia (VAP) remains one of the major causes of infection in the intensive care unit (ICU) and is associated with the length of hospital stay, duration of mechanical ventilation, and use of broad-spectrum antibiotics. We compared the frequency of VAP 10 months prior to (pre-intervention group) and 13 months after (post-intervention group) initiation of the use of a heat and moisture exchanger (HME) filter. This is a study with prospective before-and-after design performed in the ICU in a tertiary university hospital. Three hundred and fourteen patients were admitted to the ICU under mechanical ventilation, 168 of whom were included in group HH (heated humidifier) and 146 in group HME. The frequency of VAP per 1000 ventilator-days was similar for both the HH and HME groups (18.7 vs 17.4, respectively; P = 0.97). Duration of mechanical ventilation (11 vs 12 days, respectively; P = 0.48) and length of ICU stay (11 vs 12 days, respectively; P = 0.39) did not differ between the HH and HME groups. The chance of developing VAP was higher in patients with a longer ICU stay and longer duration of mechanical ventilation. This finding was similar when adjusted for the use of HME. The use of HME in intensive care did not reduce the incidence of VAP, the duration of mechanical ventilation, or the length of stay in the ICU in the study population

Low pressure support changes the rapid shallow breathing index (RSBI) in critically ill patients on mechanical ventilation

Background: The rapid shallow breathing index (RSBI) is the most widely used index within intensive care units as a predictor of the outcome of weaning, but differences in measurement techniques have generated doubts about its predictive value. Objective: To investigate the influence of low levels of pressure support (PS) on the RSBI value of ill patients. Method: Prospective study including 30 patients on mechanical ventilation (MV) for 72 hours or more, ready for extubation. Prior to extubation, the RSBI was measured with the patient connected to the ventilator (Drager (TM) Evita XL) and receiving pressure support ventilation (PSV) and 5 cmH(2)O of positive end expiratory pressure or PEEP (RSBI_MIN) and then disconnected from the VM and connected to a Wright spirometer in which respiratory rate and exhaled tidal volume were recorded for 1 min (RSBI_ESP). Patients were divided into groups according to the outcome: successful extubation group (SG) and failed extubation group (FG). Results: Of the 30 patients, 11 (37%) failed the extubation process. In the within-group comparison (RSBI_MIN versus RSBI_ESP), the values for RSBI_MIN were lower in both groups: SG (34.79 +/- 4.67 and 60.95 +/- 24.64) and FG (38.64 +/- 12.31 and 80.09 +/- 20.71; p&lt;0.05). In the between-group comparison, there was no difference in RSBI_MIN (34.79 +/- 14.67 and 38.64 +/- 12.31), however RSBI_ESP was higher in patients with extubation failure: SG (60.95 +/- 24.64) and FG (80.09 +/- 20.71; p&lt;0.05). Conclusion: In critically ill patients on MV for more than 72h, low levels of PS overestimate the RSBI, and the index needs to be measured with the patient breathing spontaneously without the aid of pressure support.Contextualização: O índice de respiração rápida e superficial (IRRS) tem sido o mais utilizado dentro das unidades de terapia intensiva \ud (UTIs) como preditor do resultado do desmame, porém diferenças no método de obtenção têm gerado dúvidas quanto a seu valor \ud preditivo. Objetivo: Verificar a influência de baixos níveis de pressão de suporte (PS) no valor do IRRS em pacientes graves. Método: \ud Estudo prospectivo, incluindo 30 pacientes sob ventilação mecânica (VM) por 72 horas ou mais, prontos para extubação. Anteriormente \ud à extubação, o IRRS foi obtido com o paciente conectado ao ventilador Evita-XL da Drager™ recebendo pressão de suporte ventilatório \ud (PSV) e PEEP=5 cmH2\ud O (IRRS_MIN) e, logo após, desconectado da VM e conectado a um ventilômetro de Wright™, onde sua frequência \ud respiratória e o volume corrente exalado eram registrados durante 1 minuto (IRRS_ESP). Os pacientes foram divididos de acordo com \ud o desfecho em grupo sucesso extubação (GS) e grupo insucesso extubação (GI). Resultados: Dos 30 pacientes, 11 (37%) falharam no \ud processo de extubação. Na comparação intragrupos (IRRS_MIN x IRRS_ESP), os valores foram menores para o IRRS_MIN em ambos \ud os grupos: GS (34,79±4,67 e 60,95±24,64) e GI (38,64±12,31 e 80,09±20,71) (p<0,05). Na comparação intergrupos não houve diferença \ud entre IRRS_MIN (34,79±14,67 e 38,64±12,31), por outro lado, IRRS_ESP foi maior nos pacientes com falha na extubação: GS (60,95±24,64) \ud e GI (80,09±20,71) (p<0,05). Conclusão: Em pacientes graves e sob VM acima de 72 horas, níveis mínimos de PS superestimam o IRRS, \ud sendo necessária sua obtenção com o paciente respirando de forma espontânea sem o auxílio de PS

Thermodiluition cardiac output measurements

The purpose of this paper is to review the aspects concerning the invasive hemodynamic monitoring of the Swan-Ganz catheter. This routine, at the bedside, will be analysed regarding its indications, its insertion techniques, the checking of this position ¾&nbsp; through the surveillance of the pressure waves and the pulmonary capillary wedge pressure, and the thorax radiography ¾&nbsp; and its steps for the hemodynamic measurements, examining the main error factors that can be perpetrated, and the possible complications succeeding that procedure. &nbsp; &nbsp;O objetivo deste artigo é revisar todos os aspectos envolvidos na monitorização hemodinâmica invasiva do uso do cateter de Swan-Ganz. Esta prática, à beira do leito, será analisada em termos da sua indicação, da sua técnica de introdução, da verificação do seu posicionamento ¾ através do acompanhamento das ondas de pressão e de encunhamento, e da radiografia do tórax ¾&nbsp; e do procedimento para as medidas hemodinâmicas, discutindo-se os principais fatores de erros que podem ser cometidos e as possíveis complicações do uso desse procedimento. &nbsp; &nbsp