Anaesthesia and intensive care
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Anaesth Intensive Care · May 2011
Intrabronchial airway pressures in intubated patients during bronchoscopy under volume controlled and pressure controlled ventilation.
Bronchoscope insertion through an endotracheal tube increases airflow resistance. Constant tidal volume (T(v)) ventilation can be maintained by augmenting the inspiratory pressure, but increased outflow resistance cannot be compensated for. Air trapping distal to the tube may lead to higher airway pressures in volume controlled (VC) mode and reduced T(v) in pressure controlled (PC) mode. ⋯ In PC mode, peak airway pressure was unchanged and end-expiratory airway pressure increased from 9.5 cmH2O (7 to 10) to 10.5 cmH2O (9 to 18) (P = 0.017). Median T(v) was reduced from 673 ml (585 to 800) to 450 ml (408 to 560) (P = 0.012); median P(a)CO2 increased from 5.7 kPa to 6.5 kPa (P = 0.012). Using distal measurement, positive end-expiratory airway pressure increased markedly in VC mode but only marginally in PC mode after bronchoscope insertion.
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Anaesth Intensive Care · May 2011
Rohrer's constant, K2, as a factor of determining inspiratory resistance of common adult endotracheal tubes.
The aim of the study was to calculate the in vitro inspiratory resistance (R(ETT)) of adult endotracheal tubes (ETT), via the end-inspiratory occlusion method, and to apply this method in vivo in order to estimate R(ETT) value in real time. By plotting R(ETT) over inspiratory flow (V) and calculating Rohrer's coefficients of linear and nonlinear resistance, K1 and K2 respectively, we determined the resistive behaviour of each ETT. Peak and plateau pressures were recorded at both proximal and distal sites of the ETT after applying a three-second occlusion under constant flow. ⋯ The intraluminal catheter increased R(ETT) No.7.0 by an average of 49%. Finally, ten patients with partially obstructed ETTs were tested and K2 in vivo constants found to be higher than their corresponding in vitro values (P value 0.00012). Therefore, knowing the performing size of an ETT may help the clinicians identify ETT obstruction and deal with weaning problems.
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Anaesth Intensive Care · May 2011
Observational study of anaesthetists' fresh gas flow rates during anaesthesia with desflurane, isoflurane and sevoflurane.
Reducing excessive fresh gas flow rates (FGF) is an established and simple strategy to reduce the administration of volatile anaesthetic agents. We studied clinicians' FGF use to understand better why two previous clinical trials achieved significant reductions in FGF by using feedback to anaesthetists. Anaesthesia information management system data from a US academic medical centre were analysed retrospectively. ⋯ Even if all anaesthetists had identical mean FGF, the standard deviation of FGF among cases would be reduced by less than 0.1 l/minute for all agents. Most of the achievable reductions in FGF were small reductions in FGF for the many cases with < 3 l/minute. These results show that departments choosing to use inexpensive automatic email feedback on FGF should target all anaesthetists and focus on variation in FGF among anaesthetists' cases.
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Anaesth Intensive Care · May 2011
Comment Letter Case ReportsThe use of sugammadex to reverse rocuronium in a patient with myotonic dystrophy.