Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2020
Comparative StudyPerformance of Air Seal of Flexible Reinforced Laryngeal Mask Airway in Thyroid Surgery Compared With Endotracheal Tube: A Randomized Controlled Trial.
Why is this important?
Indications for the use of laryngeal mask airways (LMAs) increasingly challenge our airway choice for surgical procedures where endotracheal intubation has been the norm. Thyroid surgery, with its limited anaesthetic access to the airway and potential for airway obstruction, has not typically been a first choice for LMA use.
Proponents point to avoiding muscle relaxants and reducing throat pain and laryngeal trauma as the main benefits.
What did they do?
Gong and team randomised 138 ASA 1 & 2 adults to either flexible (reinforced) LMA or intubation with an ETT (7.0 or 7.5 mm). Notably any patients with surgical complexity or BMI > 30 kg/m2 were excluded. The study was single-blinded.
Concluding
The researchers reported the upper 95%-CI for estimated mean difference in peak airway pressure as +0.96 cmH2O, and for endtidal-CO2 +1.99 mmHg – neither of which are clinically significant.
They concluded that flexible-LMA was non-inferior to ETT in terms of PAP and ET-CO2.
Hang on...
The relevance of this study to most thyroid surgical patients is however limited at best. Not only were common groups of patients excluded (ie. BMI > 30) but one of the major arguments for LMA use (avoiding muscle relaxants) was irrelevant: all patients were paralysed with rocuronium.
Further, in 7% of the LMA cases severe air-leak occured and the surgical team were asked to cease or reduce tracheal traction.
Be smart
Although the journal editors conclude in their Key Points that "FLMA is a safe alternative for experienced anesthesiologists in thyroid surgery" this seems quite a stretch given that this small study was neither powered for safety and only investigated airway ventilation performance as a narrow surrogate for acceptability.
Additionally the authors themselves highlight very real surgical concerns that LMA use can distort pharyngeal anatomy with serious consequences.
Not dissimilar to arguments for LMA use in GA caesarean section, the use of an LMA for thyroid surgery edges toward 'just because we can, does not mean we should'.
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Anesthesia and analgesia · Jan 2020
Comparative Study Observational StudyVentilator Mode Does Not Influence Blood Loss or Transfusion Requirements During Major Spine Surgery: A Retrospective Study.
Blood loss during adult spinal deformity surgery is multifactorial. Anesthetic-related factors, such as mode of mechanical ventilation, may contribute to intraoperative blood loss. The aim of this study was to determine the influence of ventilator mode and ventilator parameters on intraoperative blood loss and transfusion requirements in patients undergoing prone position spine surgery. ⋯ In prone position spine surgery, neither mode of mechanical ventilation nor airway pressure is associated with intraoperative blood loss or need for allogeneic transfusion. Use of modern ventilation strategies using lung protective techniques may mitigate differences in blood loss previously observed between PCV and VCV modes.
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Anesthesia and analgesia · Jan 2020
Comparative Study Observational StudyMonitoring Depth of Hypnosis: Mid-Latency Auditory Evoked Potentials Derived aepEX in Children Receiving Desflurane-Remifentanil Anesthesia.
The aepEXplus monitoring system, which uses mid-latency auditory evoked potentials to measure depth of hypnosis, was evaluated in pediatric patients receiving desflurane-remifentanil anesthesia. ⋯ The aepEX can reliably differentiate between a conscious and an unconscious state in pediatric patients receiving desflurane-remifentanil anesthesia.
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Anesthesia and analgesia · Jan 2020
Randomized Controlled TrialImpact of Caffeine Ingestion on the Driving Performance of Anesthesiology Residents After 6 Consecutive Overnight Work Shifts.
Residency training in anesthesiology involves care of hospitalized patients and necessitates overnight work, resulting in altered sleep patterns and sleep deprivation. Caffeine consumption is commonly used to improve alertness when fatigued after overnight work, in preparation for the commute home. ⋯ After consuming a caffeinated energy drink on conclusion of 6 shifts of night-float work, anesthesiology residents had improved control of driving performance variables in a high-fidelity driving simulator, including a significant reduction in collisions as well as slightly faster reaction times.
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Anesthesia and analgesia · Jan 2020
Randomized Controlled TrialDose-Response Study of 4 Weight-Based Phenylephrine Infusion Regimens for Preventing Hypotension During Cesarean Delivery Under Combined Spinal-Epidural Anesthesia.
Prophylactic IV infusion of phenylephrine has been recommended to prevent hypotension during spinal anesthesia for cesarean delivery. However, the optimal infusion dose is unknown. This study aimed to determine the infusion dose of phenylephrine that would be effective in preventing hypotension in 50% (ED50) and 90% (ED90) of patients when administered as a prophylactic infusion at a fixed rate based on the individual body weight. ⋯ Under the conditions of this study, when phenylephrine was given as a fixed-rate prophylactic infusion during spinal anesthesia for cesarean delivery to prevent hypotension, the values for ED50 and ED90 were 0.31 (95% CI, 0.24-0.36) and 0.54 (95% CI, 0.46-0.76) µg/kg/min, respectively.