Minerva anestesiologica
-
The recording of dead space will give information on how much of total ventilation that reaches both ventilated and perfused alveoli and thus allows gas exchange between alveoli and pulmonary blood. Realising that CO2 retention can be an effect not only of low total ventilation but also of increased dead space is one important information. Moreover, dead space will give insight into the matching of ventilation and perfusion. ⋯ However, both are subjected to potential errors that have to be considered to make a dead space recording meaningful. A correct measurement and calculation of the dead space will give valuable information on the ventilatory support of the critically ill patient and can also be a valuable diagnostic tool. It should therefore not be forgotten in the intensive care setting.
-
Hypercapnia has traditionally been avoided in the quest to keep parameters normal. Recent understanding of the role of excessive tidal stretch has prompted clinicians to avoid high tidal volumes or plateau pressures, and the resulting permissive hypercapnia has been increasingly tolerated by clinicians. Newer data point to the potential for elevated CO2 to be protective, and in some experimental situations, to cause harm. The protective effects of so called therapeutic hypercapnia' remain experimental at present, but promising laboratory studies suggest potential roles for the eventual selective application at the bedside.
-
Minerva anestesiologica · Jun 2006
Review Multicenter StudyCaudal anesthesia in pediatrics: an update.
Caudal anesthesia is one of the most used-popular regional blocks in children. This technique is a useful adjunct during general anesthesia and for providing postoperative analgesia after infraumbilical operations. The quality and level of the caudal blockade is dependent on the dose, volume, and concentration of the injected drug. Although it is a versatile block, one of the major limitations of the single-injection technique is the relatively short duration of postoperative analgesia. The most frequently used method to further prolong postoperative analgesia following caudal block is to add different adjunct drugs to the local anesthetics solution. Only few studies evaluated quality and duration of caudal block against the volume of the local anaesthetic applied. After reviewing recent scientific literature, the authors compare the duration of postoperative analgesia in children scheduled for hypospadia repair when 2two different volumes and concentrations of a fixed dose of ropivacaine are used. ⋯ In children undergoing hypospadia repair, caudal block with a ''high volume, low concentration'' regimen produces prolonged analgesia and less motor block, compared to a ''low volume, high concentration'' regimen.
-
Minerva anestesiologica · Jun 2006
Review Comparative StudyLow vs high positive end-expiratory pressure in the ventilatory management of acute lung injury.
Positive end-expiratory pressure (PEEP) has become an essential component of the care of many critically ill patients who require ventilatory support. The application of PEEP is expected to improve lung mechanics and gas exchange as it recruits lung volume. ⋯ Although the data from those animal studies and clinical trials could be seen as very convincing, there are insufficient data to propose an universal approach for the use of PEEP in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In this article I will review the basic mechanisms of PEEP and the current knowledge of the effects of PEEP on the evolution and outcome of ALI/ARDS.
-
Minerva anestesiologica · Jun 2006
ReviewVolumetric capnography in the mechanically ventilated patient.
Expiratory capnogram provides qualitative information on the waveform patterns associated with mechanical ventilation and quantitative estimation of expired CO2. Volumetric capnography simultaneously measures expired CO2 and tidal volume and allows identification of CO2 from 3 sequential lung compartments: apparatus and anatomic dead space, from progressive emptying of alveoli and alveolar gas. Lung heterogeneity creates regional differences in CO2 concentration and sequential emptying contributes to the rise of the alveolar plateau and to the steeper the expired CO2 slope. ⋯ Calculations derived from volumetric capnography are useful to suspect pulmonary embolism at the bedside. Alveolar dead space is large in acute lung injury and when the effect of positive end-expiratory pressure (PEEP) is to recruit collapsed lung units resulting in an improvement of oxygenation, alveolar dead space may decrease, whereas PEEP-induced overdistension tends to increase alveolar dead space. Finally, measurement of physiologic dead space and alveolar ejection volume at admission or the trend during the first 48 hours of mechanical ventilation might provide useful information on outcome of critically ill patients with acute lung injury or acute respiratory distress syndrome.