25 May 09
Posted in Echocardiography, Mechanical ventilation at 2:15 by Laci
By B Lamia, J Maizel, A Ochagavia, D Chemla, D Osman, C Richard, JL Teboul
Crit Care Med 2009; 37:1696-1701
Weaning-induced pulmonary edema is a cause of weaning failure in high-risk patients. The diagnosis may require pulmonary artery catheterization to demonstrate increased pulmonary artery occlusion pressure (PAOP) during weaning. Transthoracic echocardiography can estimate left ventricular filling pressures using early (E) and late (A) peak diastolic velocities measured with Doppler transmitral flow, and tissue Doppler imaging of mitral annulus velocities including early (Ea) peak diastolic velocity. We tested the hypothesis that E/A and E/Ea could be used to detect weaning-induced PAOP elevation defined by a PAOP >=18 mm Hg during a spontaneous breathing trial (SBT).
Measurements and main results
We included 39 patients who previously failed two consecutive SBTs. A third SBT was performed over a maximum 1-hour period using a T-piece. The PAOP, E/A, and E/Ea were measured before and during this SBT. Receiver operating characteristic curves were constructed to determine the optimal sensitivity and specificity values of E/A and E/Ea obtained at the end of the SBT for predicting a weaning-induced PAOP elevation. Weaning-induced PAOP elevation occurred in 17 patients. A value of E/A >0.95 at the end of the SBT predicted weaning-induced PAOP elevation with a sensitivity of 88% and a specificity of 68%. A value of E/Ea >8.5 at the end of the SBT predicted weaning-induced PAOP elevation with a sensitivity of 94% and a specificity of 73%. The combination of E/A >0.95 and E/Ea >8.5 predicted a weaning-induced PAOP elevation with a sensitivity of 82% and a specificity of 91%.
Conclusion
At the end of an SBT, the combination of E/A >0.95 and E/Ea >8.5 measured with transthoracic echocardiography allowed an accurate noninvasive detection of weaning-induced PAOP elevation.
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10 May 09
Posted in Obstructive sleep apnea, Pre-operatie evaluation at 18:46 by Laci
By F Chung, H Elsaid
Current Opinion in Anaesthesiology 2009;22:405-411
The purpose of this article is to review the screening tools available in the preoperative clinic for patients at risk of obstructive sleep apnea.
Recent findings
Obstructive sleep apnea (OSA) is the most prevalent sleep disorder. An estimated 82% of men and 92% of women with moderate-to-severe sleep apnea have not been diagnosed. Patients with undiagnosed OSA may have increased perioperative complications. The perioperative risk of patients with OSA may be reduced by appropriate screening to detect undiagnosed OSA in patients. The snoring (S), tiredness (T) during daytime, observed apnea (O), and high blood pressure (P) (STOP) questionnaire is a concise and easy-to-use screening tool to identify patients with a high risk of OSA. It has been validated in surgical patients at preoperative clinics as a screening tool. Incorporating BMI, age, neck size and gender into the STOP questionnaire (STOP-Bang), will further increase the sensitivity and negative predictive value (NPV), especially for patients with moderate-to-severe OSA.
Summary
The STOP questionnaire is short and can be easily incorporated into routine screening of general or surgical patients.
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Posted in Fluid management at 18:44 by Laci
By N Villela, B Vazques, M Intaglietta
Current Opinion in Anaesthesiology 2009;22:163-167
Plasma expanders are reviewed to determine their ability to restore microvascular function as a means for extending the transfusion trigger and delaying the use of blood transfusions. This outcome is currently achievable because of the emergence of a new understanding of optimal tissue function that prioritizes maintenance of functional capillary density, which results from the normalization of blood viscosity via the increase in plasma viscosity with new viscogenic colloids.
Recent findings
Use of viscous plasma expanders in experimental models of extreme hemodilution, hemorrhagic shock and endotoxemia shows that the limiting factor in anemia is not oxygen-carrying capacity but the decline of microvascular function due to the lowering of functional capillary density. In support of this hypothesis, we find that viscogenic colloids including high-molecular-weight starches, dextrans, polyvinylpyrrolidone, keratin and polyethylene glycol-conjugated albumin maintain or restore microvascular function in extreme hemodilution, polyethylene glycol-conjugated albumin yielding the best results.
Summary
Preclinical studies show that polyethylene glycol-conjugated albumin at concentrations in the range of 2-4% extends the transfusion trigger, providing the more extended and complete microvascular and systemic recovery from hemorrhagic shock, extreme hemodilution and endotoxemia, postponing the need of reestablish intrinsic blood oxygen-carrying capacity to hemoglobin concentrations lower than those associated with accepted transfusion triggers.
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Posted in Anesthesia at 18:42 by Laci
By J Campos
Current Opinion in Anaesthesiology 2009;22:4-10
This review is focused on tracheobronchial anatomy and the use of flexible fiberoptic bronchoscopy in thoracic anesthesia.
Recent findings
A complete knowledge of tracheobronchial anatomy is a key factor in determining proper position of lung isolation devices, namely double-lumen endotracheal tubes and bronchial blockers. In addition, changes occur in tracheobronchial anatomy with age; therefore, it is very important that every anesthesiologist is familiar with these anatomical changes in order to recognize anatomical landmarks and perform a successful placement of lung isolation devices. Flexible fiberoptic bronchoscopy must be considered an art in the practice of thoracic anesthesia.
Summary
Recognition of tracheobronchial anatomy and familiarity with the use of flexible fiberoptic bronchoscope are key components while managing patients undergoing thoracic surgery and anesthesia.
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