Erector spinae plane block level does not impact analgesic efficacy in enhanced recovery for lumbar spine surgery.

BACKGROUND CONTEXT: Postoperative pain control following spine surgery can be difficult. The Enhanced Recovery After Surgery (ERAS) programs use multimodal approaches to manage postoperative pain. While an erector spinae plane block (ESPB) is commonly utilized, the ideal distance for injection from the incision, referred to as the ES (ESPB to mid-surgical level) distance, remains undetermined. PURPOSE: We evaluated the impact of varying ES distances for ESPB on Numerical Rating Scale (NRS) measures of postoperative pain within the ERAS protocol. STUDY DESIGN/SETTING: Retrospective observational study. PATIENT SAMPLE: Adult patients who underwent elective lumbar spine fusion surgery. OUTCOME MEASURES: Primary outcome measures include the comparative postoperative NRS scores across groups at immediate (T1), 24 (T2), 48 (T3), and 72 (T4) hours postsurgery. For secondary outcomes, a propensity matching analysis compared these outcomes between the ERAS and non-ERAS groups, with opioid-related recovery metrics also assessed. METHODS: All included patients were assigned to one of three ERAS groups according to the ES distance: Group 1 (G1, ES > 3 segments), Group 2 (G2, ES = 2-3 segments), and Group 3 (G3, ES<2 segments). Each patient underwent a bilateral ultrasound-guided ESPB with 60 mL of diluted ropivacaine or bupivacaine. RESULTS: Patients within the ERAS cohort reported mild pain (NRS < 3), with no significant NRS variation across G1 to G3 at any time. Sixty-five patients were matched across ERAS and non-ERAS groups. The ERAS group exhibited significantly lower NRS scores from T1 to T3 than the non-ERAS group. Total morphine consumption during hospitalization was 26.7 mg for ERAS and 41.5 mg for non-ERAS patients. The ERAS group resumed water and food intake sooner and had less postoperative nausea and vomiting. CONCLUSIONS: ESPBs can be effectively administered at or near the mid-surgical level to the low thoracic region for lumbar spine surgeries. Given challenges with sonovisualization, a lumbar ESPB may be preferred to minimize the risk of inadvertent pleural injury.

Logistic Regression Is Non-Inferior to the Response Surface Model in Patient Response Prediction of Video-Assisted Thoracoscopic Surgery.

Response surface models (RSMs) are a new trend in modern anesthesia. RSMs have demonstrated significant applicability in the field of anesthesia. However, the comparative analysis between RSMs and logistic regression (LR) in different surgeries remains relatively limited in the current literature. We hypothesized that using a total intravenous anesthesia (TIVA) technique with the response surface model (RSM) and logistic regression (LR) would predict the emergence from anesthesia in patients undergoing video-assisted thoracotomy surgery (VATS). This study aimed to prove that LR, like the RSM, can be used to improve patient safety and achieve enhanced recovery after surgery (ERAS). This was a prospective, observational study with data reanalysis. Twenty-nine patients (American Society of Anesthesiologists (ASA) class II and III) who underwent VATS for elective pulmonary or mediastinal surgery under TIVA were enrolled. We monitored the emergence from anesthesia, and the precise time point of regained response (RR) was noted. The influence of varying concentrations was examined and incorporated into both the RSM and LR. The receiver operating characteristic (ROC) curve area for Greco and LR models was 0.979 (confidence interval: 0.987 to 0.990) and 0.989 (confidence interval: 0.989 to 0.990), respectively. The two models had no significant differences in predicting the probability of regaining response. In conclusion, the LR model was effective and can be applied to patients undergoing VATS or other procedures of similar modalities. Furthermore, the RSM is significantly more sophisticated and has an accuracy similar to that of the LR model; however, the LR model is more accessible. Therefore, the LR model is a simpler tool for predicting arousal in patients undergoing VATS under TIVA with Remifentanil and Propofol.

Opioid-sparing anesthesia with dexmedetomidine provides stable hemodynamic and short hospital stay in non-intubated video-assisted thoracoscopic surgery: a propensity score matching cohort study.

OBJECTIVES: Dexmedetomidine is an alpha-2 agonist with anti-anxiety, sedative, and analgesic effects and causes a lesser degree of respiratory depression. We hypothesized that the use of dexmedetomidine in non-intubated video-assisted thoracic surgery (VATS) may reduce opioid-related complications such as postoperative nausea and vomiting (PONV), dyspnea, constipation, dizziness, skin itching, and cause minimal respiratory depression, and stable hemodynamic status. METHODS: Patients who underwent non-intubated VATS lung wedge resection with propofol combined with dexmedetomidine (group D) or alfentanil (group O) between December 2016 and May 2022 were enrolled in this retrospective propensity score matching cohort study. Intraoperative vital signs, arterial blood gas data, perioperative results and treatment outcomes were analyzed. Of 100 patients included in the study (group D, 50 and group O, 50 patients), group D had a significantly lower degree of decrement in the heart rate and the blood pressure than group O. Intraoperative one-lung arterial blood gas revealed lower pH and significant ETCO2. The common opioid-related side effects, including PONV, dyspnea, constipation, dizziness, and skin itching, all of which occurred more frequently in group O than in group D. Patients in group O had significantly longer postoperative hospital stay and total hospital stay than group D, which might be due to opioid-related side effects postoperatively. CONCLUSIONS: The application of dexmedetomidine in non-intubated VATS resulted in a significant reduction in perioperative opioid-related complications and maintenance with acceptable hemodynamic performance. These clinical outcomes found in our retrospective study may enhance patient satisfaction and shorten the hospital stay.

Pharmacodynamic modeling of moderate sedation and rationale for dosing using midazolam, propofol and alfentanil.

PURPOSE: Regulations have broadened to allow moderate sedation administration for gastrointestinal endoscopy by non-anesthesia personnel. The line between moderate and deep sedation is ambiguous. Deep sedation offers patient comfort as well as greater safety concerns. Unintended deep sedation can occur if drug interactions are overlooked. We present a pharmacodynamic model for moderate sedation using midazolam, alfentanil and propofol. The model is suitable for training and devising rationales for appropriate dosing. METHODS: The study consists of two parts: modeling and validation. In modeling, patients scheduled for esophagogastroduodenoscopy (EGD) or colonoscopy sedation are enrolled. The modified observer's assessment of alertness/sedation (MOAA/S) score < 4 is defined as loss of response to represent moderate sedation. Two patient groups receiving bronchoscopy or endoscopic retrograde cholangiopancreatography (ERCP) are used for validation. Model performance is assessed by receiver operating characteristic (ROC) curves and area under the curve (AUC). Simulations are performed to demonstrate how the model is used to rationally determine drug regimen for moderate sedation. RESULTS: Interaction between propofol and alfentanil is stronger than the other pairwise combinations. Additional synergy is observed with three drugs. ROC AUC is 0.83 for the modeling group, and 0.96 and 0.93 for ERCP and bronchoscopy groups respectively. Model simulation suggests that 1 mg midazolam, 250 µg alfentanil and propofol maximally benefits from drug interactions and suitable for moderate sedation. CONCLUSION: We demonstrate the accurate prediction of a three-drug response surface model for moderate sedation and simulation suggests a rational dosing strategy for moderate sedation with midazolam, alfentanil and propofol.

Opioid and propofol pharmacodynamics modeling during brain mapping in awake craniotomy.

BACKGROUND: Awake craniotomy (AC) is performed to identify cerebral language center. The challenge of anesthesia is to maintain a calm, comfortable, and cooperative patient during the mapping phase. Response surface models (RSMs) are multidrug modeling algorithms. In this pharmacodynamic study, we investigate the first use of RSM with bispectral index (BIS) to predict patient's response to name calling (RNC) and wakefulness (complete neurological tests) during AC. METHODS: The study is performed in two phases. We prospectively enrolled 40 patients who received video-assisted thoracoscopic surgery (VATS) using propofol and fentanyl as the modeling group. Effect-site concentrations (Ce) and BIS values were recorded and a RSM is built from the data set. We verified the RSM retrospectively in AC patients, designated as the validation group. Corresponding BIS values were analyzed for RNC and wakefulness. RESULTS: A total of 155 data sets of propofol Ce, fentanyl Ce, and BIS pairs were available for modeling. The range of propofol and fentanyl Ce were 0 to 9.95 µg/mL and 0 to 3.69 ng/mL, respectively. Observed BIS ranged from 21 to 98. The model identified an additive interaction between propofol and an opioid. RNC at BIS 64 is predicted by the model and 70 is required for wakefulness. CONCLUSION: RSM built from VATS patients is verified with a separate group of AC patient. The BIS target advised for RSM-predicted wakefulness is 70. The model illustrates the timeline to wakefulness during AC under propofol and an opioid. It has implications in guiding, dosing, and estimation of time to wakefulness with propofol and an opioid.

Plasma concentration based response surface model predict better than effect-site concentration based model for wake-up time during gastrointestinal endoscopy sedation.

BACKGROUND: Sedation for esophagogastroduodenoscopy (EGD) and colonoscopy is characterized by rapid patient induction and emergence. The drugs midazolam and alfentanil have long been used for procedural sedation; however, the relationship between plasma or effect-site concentrations (Cp or Ce, respectively) and emergence remains unclear. The aim of this study is to develop patient wake-up prediction models for both Cp and Ce using response surface modeling, a pharmacodynamics tool for assessing patients' responses. METHODS: The Observer's Alertness/Sedation (OAA/S) score was used to monitor sedation depth during the examinations. Concentration pairs of midazolam and alfentanil were calculated for each of Cp and Ce using pharmacokinetic simulation software. Response surface models were developed using the Greco construct. Temporal analysis was done by comparing model-predicted wake-up time with true patient wake-up time. RESULTS: Thirty-three patients with an average body mass index of 21.85 ± 2.3 kg/m2 were pooled for analysis. The average duration of examination were 2.9 ± 1.4 min for EGD and 6.6 ± 2.7 min for colonoscopy. Seventy-five concentration pairs of midazolam and alfentanil were obtained for each Cp and Ce. The Cp-based Greco response surface model showed significant synergy between midazolam and alfentanil and was a better predictor of patient wake-up time, with an average deviation of 1.0 ± 3.9 min, while the Ce model show time deviation greater than 20 min. CONCLUSION: The early phases of drug distribution are unique and complicated by nonsteady-state concentrations, and our study revealed that Ce-based wake-up time prediction is more difficult under these circumstances.

Patient response prediction with logistic regression in gastrointestinal endoscopy under midazolam-alfentanil sedation performed as well as response surface model.

BACKGROUND: Researchers have used logistic regression (LR) and non-linear response surface models (RSMs) to predict patient responses to sedation. The reduced Greco and hierarchy RSMs have proven to be more appropriate than other RSMs in gastrointestinal endoscopies using midazolam and alfentanil. In this study, we evaluate the performance of a simpler model, LR, and compared it with that of RSM. METHODS: Thirty-three patients who received esophagogastroduodenoscopy (EGD) and colonoscopy sedation with midazolam and alfentanil were enrolled in the study. LR was performed for the EGD group and validated using the colonoscopy group. The two RSMs were performed using the same process, and performances and receiver operating characteristic (ROC) curves of the models were evaluated. RESULTS: The native EGD LR model had an ROC curve area of 0.94. For external validation, the ROC curves were 0.92, 0.94, and 0.94 for the reduced Greco, hierarchy, and LR models, respectively. Pairwise comparison between models was not significant. CONCLUSION: The LR model performed as well as RSM in generalizing the predicted sedative effect of midazolam and alfentanil during gastrointestinal endoscopies. LR may be used for generalization across patients experiencing procedures with similar stimulus intensities.

A previously published propofol-remifentanil response surface model does not predict patient response well in video-assisted thoracic surgery.

Modern anesthesia usually employs a hypnotic and an analgesic to produce synergistic sedation and analgesia. Two remifentanil-propofol interaction response surface models were used to predict sedation using Observer's Assessment of Alertness/Sedation (OAA/S) scores; one predicts an OAA/S <2 and the other <4. We hypothesized that both models would predict regained responsiveness (RR) after video-assisted thoracic surgery (VATS) to reduce total anesthesia time and make early extubation clinically relevant. We included 30 patients undergoing VATS received total intravenous anesthesia (TIVA) combined with thoracic epidural anesthesia (TEA). Pharmacokinetic profiles were calculated using Tivatrainer. Model predictions were compared with observations to evaluate the accuracy and precision of emergence model predictions. The mean (standard deviation) differences between when a patient responded to their name and the time when the model predicted a 50% probability of patient response were 30.80 ±â€Š17.77 and 13.71 ±â€Š11.35 minutes for the OAA/S <2 model and <4 model, respectively. Both models had a limited ability to predict patient response in our patients. Both models identified target concentration pairs predicting time of RR in volunteers and some elective surgeries, but another model of epidural and intravenous anesthetic combinations may be needed to predict time of RR after VATS under TIVA with TEA.

A desflurane and fentanyl dosing regimen for wake-up testing during scoliosis surgery: Implications for the time-course of emergence from anesthesia.

BACKGROUND/PURPOSE: The Stagnara wake-up test assesses neurological deficits during scoliosis surgery, and response surface interaction models for opioids and inhaled agents predicts anesthetic drug effects. We hypothesized that there is an optimal desflurane-fentanyl dosing regimen that can provide a faster and more predictable wake-up time, while also ensuring adequate analgesia during wake-up testing. METHODS: Twenty-three American Society of Anesthesiologists Class I-II scoliosis patients who received desflurane-fentanyl anesthetic regimens were enrolled in this posthoc study, and their intraoperative drug administration data were collected retrospectively. Desflurane and fentanyl effect site concentrations were calculated using pharmacokinetic models, and converted to equivalent remifentanil-sevoflurane concentrations. RESULTS: Results were fitted into Greco models for predicting the probability of an Observers Assessment of Alertness/Sedation score of <2. At time of wake-up, the models correctly predicted the probability that patients would respond to voice prompts and prodding was approximately 50%. The probability of pain intensity was distributed between 50% and 95%, indicating a low degree of pain at emergence. When comparing subgroups defined by calculated effect-site fentanyl concentrations, the wake-up time in the intermediate concentration group was significantly shorter than that in the high concentration group (p = 0.024). CONCLUSION: This study provides evidence that desflurane-fentanyl-based anesthesia is conducive to rapid emergence followed by an immediate neurological evaluation. Intermediate fentanyl effect-site concentrations (1-2 ng/mL) at time of wake-up were associated with good balance between rapid emergence and adequate analgesia. Furthermore, we believe that generalizing response surface models to a variety of inhalation agent-opioid combinations using simple relative potency relationships is possible and practical.

A Response Surface Model Exploration of Dosing Strategies in Gastrointestinal Endoscopies Using Midazolam and Opioids.

Classical midazolam-opioid combination for gastrointestinal endoscopy sedation has been adopted for decades. Dosing regimens have been studied but most require fixed dosing intervals. We intend to use a sophisticated pharmacodynamic tool, response surface model (RSM), to simulate sedation using different regimens. RSM can predict patient's response during different phases of the examination and predict patient's wake-up time with precision and without the need for fixed dosing intervals. We believe it will aid physicians in guiding their dosing strategy and timing.The study is divided into 2 parts. The first part is the full Greco RSMs development for 3 distinct phases: esophagogastroduodenoscopy (EGD), colonoscopy, and intersession (the time lapse between procedures). Observer's Assessment of Alertness Score (OAA/S) is used to assess patient response. The second part simulates 6 regimens with different characteristics using the RSMs: midazolam only, balanced midazolam and opioids, high-dose opioids and midazolam, low-dose midazolam with high-dose opioids, high-dose midazolam and low-dose opioids, and finally midazolam with continuous opioid infusion. Loss of response at 95% probability for adequate anesthesia during examination and return of consciousness at 50% probability during intersession was selected for simulation purposes.The average age of the patient population is 49.3 years. Mean BMI is 21.9 ±â€Š2.3 kg/m. About 56.7% were females and none received prior abdominal surgery. The cecal intubation rate was 100%. Only 1 patient (3%) developed temporary hypoxemia, which was promptly managed with simple measures. The RSMs for each phase showed significant synergy between midazolam and alfentanil. The balanced midazolam and alfentanil combination provided adequate anesthesia and most rapid return of consciousness. The awakening time from the final drug bolus was 7.4 minutes during EGD and colonoscopy stimulation, and 9.1 minutes during EGD simulation.Simulation of regimens with different characteristics gives insights on dosing strategies. A balanced midazolam-alfentanil regimen is adequate in providing good anesthetic depth and most rapid return of consciousness. We believe with the aid of our RSM, clinicians can perform sedation with more flexibility and precision.

Predicting the Best Fit: A Comparison of Response Surface Models for Midazolam and Alfentanil Sedation in Procedures With Varying Stimulation.

BACKGROUND: Selecting an effective dose of sedative drugs in combined upper and lower gastrointestinal endoscopy is complicated by varying degrees of pain stimulation. We tested the ability of 5 response surface models to predict depth of sedation after administration of midazolam and alfentanil in this complex model. The procedure was divided into 3 phases: esophagogastroduodenoscopy (EGD), colonoscopy, and the time interval between the 2 (intersession). METHODS: The depth of sedation in 33 adult patients was monitored by Observer Assessment of Alertness/Scores. A total of 218 combinations of midazolam and alfentanil effect-site concentrations derived from pharmacokinetic models were used to test 5 response surface models in each of the 3 phases of endoscopy. Model fit was evaluated with objective function value, corrected Akaike Information Criterion (AICc), and Spearman ranked correlation. A model was arbitrarily defined as accurate if the predicted probability is <0.5 from the observed response. RESULTS: The effect-site concentrations tested ranged from 1 to 76 ng/mL and from 5 to 80 ng/mL for midazolam and alfentanil, respectively. Midazolam and alfentanil had synergistic effects in colonoscopy and EGD, but additivity was observed in the intersession group. Adequate prediction rates were 84% to 85% in the intersession group, 84% to 88% during colonoscopy, and 82% to 87% during EGD. The reduced Greco and Fixed alfentanil concentration required for 50% of the patients to achieve targeted response Hierarchy models performed better with comparable predictive strength. The reduced Greco model had the lowest AICc with strong correlation in all 3 phases of endoscopy. Dynamic, rather than fixed, γ and γalf in the Hierarchy model improved model fit. CONCLUSIONS: The reduced Greco model had the lowest objective function value and AICc and thus the best fit. This model was reliable with acceptable predictive ability based on adequate clinical correlation. We suggest that this model has practical clinical value for patients undergoing procedures with varying degrees of stimulation.

Previously published midazolam-alfentanil response surface model cannot predict patient response well in gastrointestinal endoscopy sedation.

BACKGROUND: A response surface model is a mathematical model used to predict multiple-drug pharmacodynamic interactions. With the use of a previously published volunteer model, we tested the accuracy of the midazolam-alfentanil response surface model during gastrointestinal endoscopy. METHODS: We enrolled 35 adult patients scheduled for combined endoscopic procedures. Patients were sedated with intravenous midazolam and alfentanil, and monitored with real-time auditory evoked potential. Sedation Observer's Assessment of Alertness/Sedation (OAA/S) scores were recorded by an independent observer every 2 minutes. Patients with OAA/S scores of ≥ 4 were designated as "awake". Pharmacokinetic profiles were calculated using the TIVA trainer. The published response surface model was modified to make estimations more reasonable. Patient response (OAA/S score ≥ 4 or <4) was then estimated using the modified version of the model. RESULTS: The average procedural times were 3.3 ± 2 minutes and 6.5 ± 2.3 minutes for esophagogastroduodenoscopy and colonoscopy, respectively. The model poorly predicted patient response during gastrointestinal endoscopic procedure sedation. Accuracy in predicting an OAA/S score of <4 was 6% for the original model and 0% for the modified model. The estimated probability of loss of response ranged from 0.04% to 2.94% at the time of arousal (OAA/S score ≥ 4) and from 0.24% to 15.55% when the patient was asleep (OAA/S score < 4). CONCLUSION: The model showed significant synergy between midazolam and alfentanil; however, it was inadequate in predicting the response of patients undergoing sedated gastrointestinal endoscopic procedures. Future model parameter adjustments are required.

Successful anesthetic management of a patient with thyroid carcinoma invading the trachea with tracheal obstruction, scheduled for total thyroidectomy.

We report a case of large thyroid carcinoma with tracheal and esophageal invasion who presented with preoperative stridor scheduled for total thyroidectomy and segmental tracheal resection. Careful and comprehensive preoperative anesthetic planning was done. Extracorporeal circulation membrane oxygenation (ECMO) was set up and running prior to induction under local anesthesia, due to an increased international normalized ratio (INR) and fear of bleeding in the airway. Fiberoptic bronchoscopy (FOB) is the first choice in many circumstances of difficult airway. However, we twice failed to intubate under FOB guidance. Successful intubation was done with traditional laryngoscopy and a Glidescope. The operative course was smooth. The oral endotracheal tube (ETT) was changed to a nasal ETT after surgery with the Glidescope. FOB-assisted intubation carries a chance of failure, and in critical patients, the presence of other intubating modalities such as video-assisted or fiberoptic-assisted technology or safety measures, including ECMO, will greatly increase the safety of anesthesia and surgery.

Successful management of contrast medium extravasation injury through stellate ganglion block and intra-arterial nitroglycerin.

We describe the successful management of extravasation injury to the left hand by contrast medium with stellate ganglion block and intra-arterial nitroglycerin in a patient which befell during contrast-enhanced imaging. The incidence of contrast-medium extravasation injury is increasing because of the convenience and availability of contrast-enhanced imaging and ease of injection access. Extravasation of contrast medium may results in severe pain, erythema, cyanosis, and edema or even skin necrosis, which is largely related to the ionization, osmolarity, and volume of the contrast medium. The conservative treatment is often adequate in small amount extravasation, but if the extravasation is overwhelming further energetic management is mandatory. A 29-year-old man was brought to our emergency because of diffuse abdominal pain and he was arranged to receive intravenous contrast media enhanced abdominal computed tomography for diagnosis. Ruptured appendicitis with abscess formation was suspected; then the patient underwent emergent appendectomy and drainage of the abscess. However, severe swelling and cyanotic change that radiated from the intravenous catheter insertion site in every direction over the entire dorsum of the left hand were noted after the surgery. Contrast-medium extravasation injury was highly contemplated and a left stellate ganglion block was performed immediately for relief of symptoms. The consulting surgeon ruled out compartment syndrome, but advised emergent left upper limb arteriography, which revealed signs of vasospasm with high intravascular pressure of the left distal ulnar and radial arteries; thus nitroglycerin was injected into left distal ulnar and radial arteries for relief of vasospasm. The clinical symptoms were improved after the above managements and the patient was discharged 7 days later without any sequela.