Anaesthesia
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Observational Study
Effects of tracheal intubation and tracheal tube position on regional lung ventilation: an observational study.
Take me back to the First Part
This study confirmed the well-known observation of the ventral ventilation shift under positive pressure ventilation, and quantified the contribution from the endotrachial tube itself, versus from muscle relaxation and IPPV.
This ventral shift under IPPV has also been shown to occur during pressure support ventilation with an LMA, when compared with spontaneous breathing under GA (Radke 2012).
Using electrical impedance tomography Lumb et al. confirmed this ventral shift in supine IPPV subjects, and demonstrated that this is primarily due to IPPV rather than the ETT itself, – although they found tube presence contributed to ~16% of the change.
"The generally accepted physiological explanation ... is that of greater cephalad movement of the diaphragm in dependent vs. non‐dependent lung regions during anaesthesia, resulting in changes in regional lung compliance."
"...regional ventilation with positive pressure ventilation during anaesthesia, even with no tracheal tube in place, is grossly different when compared with spontaneous ventilation, with greater ventilation of the left lung and ventral regions of both lungs. These effects are exacerbated by ventilation through a tracheal tube, leading to a greater degree of inhomogeneity of overall ventilation compared with when awake.
Take-home message
The authors note that while anaesthetists understand the detrimental effect of inadvertent endobronchial intubation, simply having the ETT tip close to the carina also worsens V/Q mismatch and is not as well appreciated. In these situations, tube withdrawal and/or 90o rotation may improve V/Q match.
Although this may be clinical insignificant for most patients, it should be considered when needing to improve gas exchange, particularly in critical care patients.
summary -
In our previous study, a Paediatric Early Warning Score could be calculated for only one-fifth of 102,993 children transported by ambulance to hospital, as components other than supplemental oxygen were not reliably measured: respiratory rate 90,358 (88%); Glasgow Coma Score 83,648 (81%); heart rate 83,330 (81%); time to capillary reperfusion 81,685 (79%); oxygen saturation 71,372 (69%); temperature 60,402 (59%); systolic blood pressure 37,088 (36%). We tested 12 abbreviated scores with 3-5 components. ⋯ Scores could be calculated for at most 74,508 (72%) children when heart rate, conscious level and respiratory rate were measured, with or without supplemental oxygen: the discrimination of these two versions was 0.75 and 0.77, respectively. Optimal threshold scores of 3 and 2 for these two abbreviated versions discriminated an outcome rate of 2-3% in about one third of children from the other children who had < 1% rate of outcome.
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Review Meta Analysis
Analgesic benefits and clinical role of the posterior suprascapular nerve block in shoulder surgery: a systematic review, meta-analysis and trial sequential analysis.
Although suprascapular nerve block reduces nausea & vomiting and improves patient satisfaction after shoulder surgery when compared to morphine alone, it results only in clinically insignificant objective improvement of analgesia.
pearl