Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2002
The mission of the cochrane anesthesia review group: preparing and disseminating systematic reviews of the effect of health care in anesthesiology.
This article illustrates the basic principles of evidence-based medicine and the work within the Cochrane Collaboration and the Cochrane Anesthesia Review Group. It describes how important randomized controlled trials and systematic reviews are in providing the best evidence to answer clinically relevant questions.
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Anesthesia and analgesia · Oct 2002
Comparative Study Clinical TrialPreload index: pulmonary artery occlusion pressure versus intrathoracic blood volume monitoring during lung transplantation.
In this study, during lung transplantation, we analyzed a conventional preload index, the pulmonary artery occlusion pressure (PAOP), and a new preload index, the intrathoracic blood volume index (ITBVI), derived from the single-indicator transpulmonary dilution technique (PiCCO System), with respect to stroke volume index (SVIpa). We also evaluated the relationships between changes (Delta) in ITBVI and PAOP and DeltaSVIpa during lung transplantation. The reproducibility and precision of all cardiac index measurements obtained with the transpulmonary single-indicator dilution technique (CIart) and with the pulmonary artery thermodilution technique (CIpa) were also determined. Measurements were made in 50 patients monitored with a pulmonary artery catheter and with a PiCCO System at six stages throughout the study. Changes in the variables were calculated by subtracting the first from the second measurement (Delta(1)) and so on (Delta(1) to Delta(5)). The linear correlation between ITBVI and SVIpa was significant (r(2)=0.41; P < 0.0001), whereas PAOP poorly correlated with SVIpa (r(2) = -0.01). Changes in ITBVI correlated with changes in SVIpa (Delta(1), r(2) = 0.30; Delta(2), r(2) = 0.57; Delta(4), r(2) = 0.26; and Delta(5), r(2) = 0.67), whereas PAOP failed. The mean bias between CIart and CIpa was 0.15 l. min(-1). m(-2) (1.37). In conclusion, ITBVI is a valid indicator of cardiac preload and may be superior to PAOP in patients undergoing lung transplantation. ⋯ The assessment of intrathoracic blood volume index (ITBVI) by the transpulmonary single-indicator technique is a useful tool in lung transplant patients, providing a valid index of cardiac preload that may be superior to pulmonary artery occlusion pressure. However, more prospective, randomized studies are necessary to evaluate the role and limitations of this technique.
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Anesthesia and analgesia · Oct 2002
Difficult endotracheal intubation in patients with sleep apnea syndrome.
Although sleep apnea syndrome (SAS) is common, studies assessing the anesthetic management of these patients are rare and consist mainly of case studies. We performed a retrospective case-control study to determine the incidence of difficult intubation in SAS patients and to determine the relationship between the severity of SAS and the occurrence of difficult intubation. Among 113 patients included (36 and 77 in the SAS and control groups, respectively), difficult intubation occurred more often in SAS patients than in controls (21.9% versus 2.6%, respectively; P < 0.05). No relationship was found between the severity of SAS and the occurrence of difficult intubation. Disappointingly, no single factor was associated with the occurrence of difficult intubation in SAS patients. We conclude that SAS is a risk factor for difficult intubation. ⋯ Because patients with sleep apnea syndrome have an increased risk of difficult endotracheal intubation and may present with cardiovascular disease, preoperative preventive measures should be undertaken to avoid untoward events.
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Anesthesia and analgesia · Oct 2002
A neurosteroid anesthetic, alphaxalone, inhibits nicotinic acetylcholine receptors in cultured bovine adrenal chromaffin cells.
Several lines of evidence suggest that nicotinic acetylcholine receptors (nAChRs) are a target of general anesthetics. Alphaxalone (5alpha-pregnan-3alpha-ol-11, 20-dion) is a neurosteroid, which was used clinically for anesthesia, but its effects on the function of nAChRs have not been well investigated. We examined the effects of alphaxalone on nAChRs in cultured bovine adrenal chromaffin cells. We studied the effects of alphaxalone on nicotine-induced increases in the cytosolic Ca(2+) concentration ([Ca(2+)](i)) and on membrane currents using Ca(2+)-imaging and whole-cell patch-clamp techniques, respectively, in these cells. We also examined the effects of alphaxalone on gamma-aminobutyric acid A receptors in the same cells and compared them with the effects on nAChRs. Alphaxalone (0.1-100 micro M) inhibited nicotine-induced [Ca(2+)](i) increases in a concentration-dependent manner. Alphaxalone inhibited high K(+)-induced [Ca(2+)](i) increases, but the inhibition was observed only at 100 micro M. In voltage-clamp experiments using negative holding potentials, alphaxalone (0.1-100 micro M) itself induced inward currents, which were abolished by the gamma-aminobutyric acid A receptor antagonist picrotoxin. Alphaxalone also inhibited nicotine-induced inward currents, and the inhibition was unaffected by picrotoxin. We conclude that alphaxalone, at anesthetic concentrations, inhibits nAChRs in adrenal chromaffin cells. Alphaxalone may affect the sympathetic and other nervous systems via inhibition of nAChRs. ⋯ Alphaxalone inhibits the function of nAChRs at clinically relevant concentrations in adrenal chromaffin cells. Thus, the present findings may provide some information for understanding the anesthetic mechanism of alphaxalone.
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Anesthesia and analgesia · Oct 2002
Hypertonic-hyperoncotic solutions reduce the release of cardiac troponin I and s-100 after successful cardiopulmonary resuscitation in pigs.
In some patients, cardiopulmonary resuscitation (CPR) can revive spontaneous circulation (ROSC). However, neurological outcome often remains poor. Hypertonic-hyperoncotic solutions (HHS) have been shown to improve microvascular conductivity after regional and global ischemia. We investigated the effect of infusion of HHS in a porcine CPR model. Cardiac arrest was induced by ventricular fibrillation. Advanced cardiac life support was begun after 4 min of nonintervention and 1 min of basic life support. Upon ROSC, the animals randomly received 125 mL of either normal saline (placebo, n = 8) or 7.2% NaCl and 10% hydroxyethyl starch 200,000/0.5 (HHS, n = 7). Myocardial and cerebral damage were assessed by serum concentrations of cardiac troponin I and astroglial protein S-100, respectively, up to 240 min after ROSC. In all animals, the levels of cardiac troponin I and S-100 increased after ROSC (P < 0.01). This increase was significantly blunted in animals that received HHS instead of placebo. The use of HHS in the setting of CPR may provide a new option in reducing cell damage in postischemic myocardial and cerebral tissues. ⋯ Infusion of hypertonic-hyperoncotic solutions (HHS) after successful cardiopulmonary resuscitation in pigs significantly reduced the release of cardiac troponin I and cerebral protein S-100, which are sensitive and specific markers of cell damage. Treatment with HHS may provide a new option to improve the outcome of cardiopulmonary resuscitation.