Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2021
Relationship Between Propofol Target Concentrations, Bispectral Index, and Patient Covariates During Anesthesia.
Internationally, propofol is commonly titrated by target-controlled infusion (TCI) to maintain a processed electroencephalographic (EEG) parameter (eg, bispectral index [BIS]) within a specified range. The overall variability in propofol target effect-site concentrations (CeT) necessary to maintain adequate anesthesia in real-world conditions is poorly characterized, as are the patient demographic factors that contribute to this variability. This study explored these issues, hypothesizing that the variability in covariate-adjusted propofol target concentrations during BIS-controlled anesthesia would be substantial and that most of the remaining interpatient variability in drug response would be due to random effects, thus suggesting that the opportunity to improve on the Schnider model with further demographic data is limited. ⋯ Our hypothesis was confirmed. The variability in covariate-adjusted propofol CeT30 titrated to BIS in real-world conditions is considerable, and only a small portion of the remaining variability in drug response is explained by patient demographic factors. This finding may have important implications for the development of new pharmacokinetic (PK) models for propofol TCI.
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Anesthesia and analgesia · Mar 2021
Comparative StudyComparison of Chloroprocaine Versus Lidocaine With Epinephrine, Sodium Bicarbonate, and Fentanyl for Epidural Extension Anesthesia in Elective Cesarean Delivery: A Randomized, Triple-Blind, Noninferiority Study.
For emergent intrapartum cesarean delivery (CD), the literature does not support the use of any particular local anesthetic solution to extend epidural analgesia to cesarean anesthesia. We hypothesized that 3% chloroprocaine (CP) would be noninferior to a mixture of 2% lidocaine, 150 µg of epinephrine, 2 mL of 8.4% bicarbonate, and 100 µg of fentanyl (LEBF) in terms of onset time to surgical anesthesia. ⋯ Both anesthetic solutions have a rapid onset of anesthesia when used to extend low-dose epidural sensory block to surgical anesthesia. Data from the current study provide insufficient evidence to confirm that CP is noninferior to LEBF for rapid epidural extension anesthesia for CD, and further research is required to determine noninferiority.
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Anesthesia and analgesia · Mar 2021
Predicting Unacceptable Pain in Cardiac Surgery Patients Receiving Morphine Maintenance and Rescue Doses: A Model-Based Pharmacokinetic-Pharmacodynamic Analysis.
Optimal analgesic treatment following cardiac surgery is crucial for both patient comfort and successful postoperative recovery. While knowledge of both the pharmacokinetics and pharmacodynamics of analgesics is required to predict optimal drug dosing, models quantifying the pharmacodynamics are scarce. Here, we quantify the pharmacodynamics of morphine by modeling the need for rescue morphine to treat unacceptable pain in 118 patients after cardiac surgery. ⋯ The pharmacodynamics of morphine after cardiac surgery was successfully quantified using RTTE modeling. Future studies can be used to expand the model to better predict morphine's pharmacodynamics on the individual level and to include the pharmacodynamics of other analgesics so that improved postoperative pain treatment protocols can be developed.
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Anesthesia and analgesia · Mar 2021
Randomized Controlled Trial Multicenter Study Comparative StudyHead Rotation Reduces Oropharyngeal Leak Pressure of the i-gel and LMA® Supreme™ in Paralyzed, Anesthetized Patients: A Randomized Trial.
This airway study is a neat little randomised-but-not-blinded study of the effect of head rotation on the oropharyngeal leak pressure of both the i-gel and LMA Supreme 2nd generation supraglottic airways.
The researchers investigated the leak pressure (OPLP) of the i-gel and LMA Supreme in paralysed patients with the head: 1. neutral, 2. rotated 30°, and 3. rotated 60°. They found that rotation of the head through 30° and 60° progressively increased OPLP by a clinically-significantly amount (0° vs 60° 5.5 cmH2O (3.3-7.8) & 6.5 cmH2O (5.1-8.0) respectively).
Before you get too excited...
The result however may not be reliably applicable to all populations, notably the study subjects were overwhelmingly small (x̄ ~160cm & 60kg) Japanese women (71%), receiving a TIVA muscle-relaxant anaesthetic (propofol, remifentanil, rocuronium). How well this improvement-with-rotation holds up among, for example, spontaneously ventilating large Caucasian males, is unclear.
Bottom-line
When using an i-gel or LMA Supreme 2nd generation supraglottic airway, careful head rotation to 60° may increased oropharyngeal leak pressure and so assist with ventilation troubleshooting. However head and neck rotation of anaesthetised, paralysed patients should be performed gently and cautiously – you are after all, not a chiropractor!
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