Critical care : the official journal of the Critical Care Forum
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Air-space enlargement may result from mechanical ventilation and/or lung infection. The aim of this study was to assess how mechanical ventilation and lung infection influence the genesis of bronchiolar and alveolar distention. ⋯ Lung infection induces bronchiolar and alveolar distention. Mechanical ventilation induces secondary lung infection and is associated with further air-space enlargement. The combination of primary lung infection and mechanical ventilation markedly increases air-space enlargement, the degree of which depends on the severity and extension of lung infection.
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Methadone, the most widely delivered maintenance therapy for heroin addicts, may be responsible for life-threatening poisonings with respiratory depression. The toxicokinetics and the toxicokinetic/toxicodynamic (TK/TD) relationships of methadone enantiomers have been poorly investigated in acute poisonings. The aim of this study was to describe the relationships between methadone-related respiratory effects and their corresponding concentrations. ⋯ After the ingestion of a toxic dose of a racemic mixture, plasma R- and S-enantiomer concentrations decreased in parallel. Despite large inter-individual variability in methadone toxicokinetics and toxicodynamics, TK/TD relationships would be helpful for providing quantitative data regarding the respiratory response to methadone in poisonings. However, further confirmatory TK/TD data are needed.
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Consequences of lung recruitment with prolonged high positive end-expiratory pressure (PEEP) ventilation for liver function are unclear. We therefore investigated liver dysfunction during two different ventilation treatment regimens of experimental acute respiratory distress syndrome. ⋯ The PCV+R group showed a more prominent inflammatory reaction in their liver sinusoids accompanied by increased serum levels of liver enzymes and HA. Therefore, recruitment with higher PEEP levels for treatment of respiratory failure might lead to liver dysfunction.
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Decreases in oxygen saturation (SO2) and lactate concentration [Lac] from superior vena cava (SVC) to pulmonary artery have been reported. These gradients (Delta SO2 and Delta[Lac]) are probably created by diluting SVC blood with blood of lower SO2 and [Lac]. We tested the hypothesis that Delta SO2 and Delta[Lac] result from mixing SVC and inferior vena cava (IVC) blood streams. ⋯ Mixing of SVC with IVC blood does not account for the development of Delta SO2 and Delta[Lac] in hemodynamically stable individuals with pulmonary artery hypertension. An alternate mechanism is mixing with coronary sinus blood, implying that Delta SO2 and Delta[Lac] may reflect changes in coronary sinus SO2 and [Lac] in this patient population.
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Editorial Comment
Perioperative goal directed haemodynamic therapy--do it, bin it, or finally investigate it properly?
The literature concerning the use of goal directed haemodynamic therapy (GDHT) in high risk surgical patients has been importantly increased by the study of Lopes and colleagues. Using a minimally invasive assessment of fluid status and pulse pressure variation monitoring during mechanical ventilation, improvements were seen in post-operative complications, duration of mechanical ventilation, and length of hospital and intensive care unit (ICU) stay. Many small studies have shown improved outcome using various GDHT techniques but widespread implementation has not occurred. Those caring for perioperative patients need to accept the published evidence base or undertake a larger, multi-centre study.