Minerva anestesiologica
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Minerva anestesiologica · Apr 2001
Review Randomized Controlled Trial Clinical TrialPathophysiology of prone positioning in the healthy lung and in ALI/ARDS.
Prone position was initially introduced in healthy anesthetized and paralyzed subjects for surgical specific reasons. Then, it was used during acute respiratory failure to improve gas exchange. The interest on prone position during ALI/ARDS progressively increased, even if the mechanisms leading to a respiratory improvement are not yet completely understood. ⋯ The proportion of responders increased to 85% after 6 hours of prone positioning. The incidence of maneuver-related complications and severe and life-threatening complications was extremely rare. The overall mortality at ICU discharge was 51% and the ICU stay was similar in survivors and non survivors (17.8 +/- 11.6 vs 17.8 +/- 11.4 days).
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The role of analgesia and sedation in intensive care units (ICU) is ancillary to other intensive care strategies, nevertheless they permit that every other diagnostic and therapeutic procedure is safely performed by keeping the patient pain-free, anxiety-free and cooperative. Commonly used opioids in ICU include morphine, fentanyl, sufentanil and remifentanil. The choice among opioid drugs relies on their pharmacokinetics and their pharmacodynamic effects. ⋯ The main indications for opioid analgesia and sedation in ICU include: 1) Anxiety, pain and agitation: in turn, they can increase cardiac workload, myocardial oxygen consumption and rate of dysarrhythmias; 2) immediate postoperative period after major surgery; 3) short-term invasive procedures. Potential advantages offered by opioids in the ICU setting also include: a) Cardiac protection: in animal models, it has been observed that delta-opiate receptor stimulation confers a preconditioning-like protective effects against myocardial ischemia; b) Neuroprotection: recent studies suggest that mu- and kappa-opiate receptors are involved in ischemic preconditioning against seizures in the brain. During opioid therapy in the ICU, drug tolerance and withdrawal symptoms should be anticipated and the dose adjusted accordingly.
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The pressure-volume curve of the respiratory system is a physiological method used for diagnotic purposes to describe the static mechanical properties of the respiratory system. A renewal of interest in the pressure-volume curve has recently appeared because of experimental evidence regarding the information conveyed by the curve, a better understanding of the pathophysiologic factors influencing its interpretation and the beneficial results of clinical trials based on the use of the pressure-volume curve for ventilatory management of acute respiratory distress syndrome. Thus, adapting ventilatory settings to individual characteristics of the patients in terms of respiratory mechanics may be an extremely important aspect for a better management of the most difficult to ventilate patients with acute lung injury. ⋯ The low-flow technique using ventilator technology has several potential advantages. It is hopeful to think that in the future the measurement of the P-V curve and the quantification of alveolar recruitment may be easily provided at the bedside and may help for the titration of the ventilatory settings in clinical practice. This review will focus briefly on the physiologic background, technique description, and recent advances concerning the interpretation of the P-V curve in the critically ill patients.
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Clinical shock is a common problem of the critically ill patient. Assessment of the circulating volume is important to assure adequate oxygen supply to the tissues, and hypovolaemia must be treated promptly to avoid organ dysfunction. ⋯ Clinical signs are often late indicators and the monitoring of hemodynamic variables through cardiac catheterism can be misleading. The fluid challenge approach provides a useful diagnostic test of hypovolaemia, and a method for titrating the dose of fluid tailored to the individual's requirement.
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Minerva anestesiologica · Apr 2001
ReviewPathophysiology and treatment of airway mucociliary clearance. A moving tale.
Airway hygiene depends largely on mucociliary clearance (MCC) which in turn depends upon the movement of viscoelastic mucus along the airway by the beating of the ciliary appendages of airway epithelial cells. Failure to keep the airways sterile by MCC results in a host inflammatory response to the persistent microorganisms which, if it becomes chronic, causes damage to the airway wall and upregulation of mucus production manifest clinically as bronchiectasis, sinusitis and otitis. There are three principal disorders of MCC. ⋯ Secondly, secondary ciliary dyskinesia due principally to microbial toxin-induced dysfunction of the energy pathways required for ciliary beating. Thirdly, abnormalities in the physicochemical properties of mucus, including reduced salt content/osmolality which results in it being unsuitable in quality for cilia to move it. Methods of rectifying this defect promise to restore MCC to normal and interfere in the vicious circle of inflammatory lung damage.