Ability of short-time low peep challenge to predict fluid responsiveness in mechanically ventilated patients in the intensive care.

Short-time low PEEP challenge (SLPC, application of additional 5 cmH2O PEEP to patients for 30 s) is a novel functional hemodynamic test presented in the literature. We hypothesized that SLPC could predict fluid responsiveness better than stroke volume variation (SVV) in mechanically ventilated intensive care patients. Heart rate, mean arterial pressure, stroke volume index (SVI) and SVV were recorded before SLPC, during SLPC and before and after 500 mL fluid loading. Patients whose SVI increased more than 15% after the fluid loading were defined as fluid responders. Reciever operating characteristics (ROC) curves were generated to evaluate the abilities of the methods to predict fluid responsiveness. Fifty-five patients completed the study. Twenty-five (46%) of them were responders. Decrease percentage in SVI during SLPC (SVIΔ%-SLPC) was 11.6 ± 5.2% and 4.3 ± 2.2% in responders and non-responders, respectively (p < 0.001). A good correlation was found between SVIΔ%-SLPC and percentage change in SVI after fluid loading (r = 0.728, P < 0.001). Areas under the ROC curves (ROC-AUC) of SVIΔ%-SLPC and SVV were 0.951 (95% CI 0.857-0.991) and 0.747 (95% CI 0.611-0.854), respectively. The ROC-AUC of SVIΔ%-SLPC was significantly higher than that of SVV (p = 0.0045). The best cut-off value of SVIΔ%-SLPC was 7.5% with 90% sensitivity and 96% specificity. The percentage change in SVI during SLPC predicts fluid responsiveness in intensive care patients who are ventilated with low tidal volumes; the sensitivity and specificity values are higher than those of SVV.

Learning curve of ultrasound measurement of subglottic diameter for endotracheal tube selection in pediatric patients.

BACKGROUND: Endotracheal tube size can be predicted according to ultrasound measurement of subglottic airway diameter. The learning curve for this method is not yet established. The aim was to evaluate the learning curve of anesthesiology residents in ultrasound measurement of subglottic airway diameter for prediction of endotracheal tube size using cumulative sum analysis. METHODS: Sixteen anesthesiology residents measured transverse subglottic airway diameter in children undergoing general anesthesia with cuffed endotracheal intubation. Each resident performed 30 ultrasound examinations. Primary outcome was the successful prediction of endotracheal tube size according to ultrasound measurement. Cumulative sum analysis was performed with acceptable and unacceptable failure rates set as 20 and 40%, respectively. RESULTS: Ten out of 16 residents (62.5%) were deemed successful as they were able to pass lower decision boundary, whereas six residents' CUSUM scores were between the decisions lines deeming them indeterminate. The overall success rate for determining the correct endotracheal tube size was 77.5%. Median number of attempts to cross lower decision boundary was 29 with minimum of 18 and maximum of 29 attempts among successful residents. CONCLUSION: Learning curves constructed with cumulative sum analysis in this study showed that only 62.5% of residents were able to correctly predict cuffed endotracheal tube size with 80% success rate. Considerable variability in achieving competency necessitates objective follow-up of individual improvement.

Transpulmonary thermodilution monitoring-guided hemodynamic management improves cognitive function in patients with aneurysmal subarachnoid hemorrhage: a prospective cohort comparison.

BACKGROUND: The effects of goal-directed hemodynamic management using transpulmonary thermodilution (TPT) monitor on the cognitive function of patients with aneurysmal subarachnoid hemorrhage (aSAH) remain unclear. The present study aimed to determine whether hemodynamic management with TPT monitor provides better cognitive function compared with standard hemodynamic management. METHODS: Patients with aSAH who were admitted to the intensive care unit in 2016 were assigned to cohort 1, and those admitted in 2017 were assigned to cohort 2. In cohort 1, hemodynamic and fluid management was performed in accordance with the traditional pressure-based hemodynamic parameters and clinical examination, whereas in cohort 2, it was performed in accordance with the TPT monitor-measured flow-based parameters. The incidence of delayed cerebral ischemia (DCI) and pulmonary edema (PE) was determined. The functional outcome of patients was assessed using the modified Rankin scale (mRS) score and Montreal cognitive assessment (MoCA) test at 1 year following aSAH. RESULTS: Cohort 1 included 45 patients and cohort 2 included 39 patients who completed the trial. The incidence of DCI (38% versus 26%) and PE (11% versus 3%) was comparable between the cohorts (p > 0.05). The mRS score was similar between the cohorts (p = 0.11). However, the MoCA score was 20.2 (19.2-21.4) and 23.5 (22.2-24.8) in cohort 1 and cohort 2, respectively (p < 0.001). Accordingly, the occurrence of poor MoCA score (38% versus 18%) was significantly lower in cohort 2 (p = 0.045). CONCLUSIONS: TPT monitor-based hemodynamic management provides better cognitive outcome than standard hemodynamic management in patients with aSAH.

Comparison of ability of pulse pressure variation to predict fluid responsiveness in prone and supine position: an observational study.

We aimed to compare the ability of pulse pressure variation (PPV) to predict fluid responsiveness in prone and supine positions and investigate effect of body mass index (BMI), intraabdominal pressure (IAP) and static respiratory compliance (CS) on PPV. A total of 88 patients undergoing neurosurgery were included. After standardized anesthesia induction, patients' PPV, stroke volume index (SVI), CS and IAP values were recorded in supine (T1) and prone (T2) positions and after fluid loading (T3). Also, PPV change percentage (PPVΔ%) between T2 and T1 times was calculated. Patients whose SVI increased more than 15% after the fluid loading were defined as volume responders. In 10 patients, PPVΔ% was ≤ - 20%. All of these patients had CST2 < 31 ml/cmH2O, seven had BMI > 30 kg/m2, and two had IAPT2 > 15 mmHg. In 16 patients, PPVΔ% was ≥ 20%. In these patients, 10 had CST2 < 31 ml/cmH2O, 10 had BMI > 30 kg/m2, and 12 had IAPT2 > 15 mmHg. Thirty-nine patients were volume responder. When all patients were examined for predicting fluid responsiveness, area under curves (AUC) of PPVT2 (0.790, 95%CI 0.690-0.870) was significantly lower than AUC of PPVT1 (0.937, 95%CI 0.878-0.997) with ROC analysis (p = 0.002). When patients whose CST2 was < 31 ml/cmH2O and whose BMI was > 30 kg/m2 were excluded from analysis separately, AUC of PPVT2 became similar to PPVT1. PPV in the prone can predict fluid responsiveness as good as PPV in the supine, only if BMI is < 30 kg/m2 and CS value at prone is > 31 ml/cmH2O.

Relation of gray-white matter ratio with long-term cognitive functions and quality of life in patients with mild to moderate aneurysmal subarachnoid hemorrhage: a prospective observational study.

BACKGROUND: In the present study, we hypothesized that a low gray matter-white matter ratio (GWR) is associated with poor cognitive function and low quality of life in patients with mild to moderate (WFNS ≤3) aneurysmal subarachnoid hemorrhage (aSAH). METHODS: All patients with aSAH who were admitted to the neurointensive care unit (Neuro ICU) and whose WFNS score was ≤ 3 were enrolled in the study. During the Neuro ICU follow-up period, the following variables were recorded: demographics, neurological status, comorbidities, time elapsed between onset of bleeding and Neuro ICU admission, treatment method, number of days with vasospasm symptoms (DVS) and vasopressor usage. One year after bleeding, all patients except those who could not answer the questionnaires appropriately were administered the MoCA and SF-36 tests, and brain magnetic resonance imaging and then volumetric brain analysis were performed. RESULTS: Eighty-two patients completed the study. One year after aSAH, cognitive dysfunction and low quality of life were observed in 59.8% and 25.6% of patients, respectively. Among the variables obtained during Neuro ICU follow-up, DVS was found to be a major risk factor for cognitive dysfunction (OR: 3.9, 95% CI: 1.9-7.8; p < 0.001), poor quality of life (OR: 2.8, 95% CI: 1.4-5.3, p = 0.002) and a lower GWR value (p < 0.001, correlation coefficient = -0.410, R2 = 0.234). One year after aSAH, higher GWR values were associated with higher MoCA (R2 = 0.506 for males, R2 = 0.413 for females) and SF-36 (R2 = 0.270 for males, R2 = 0.364 for females) scores in both genders. Also, GWR ≤ 1.35 in males and GWR ≤1.33 in females indicated MoCApoor patients with over 80% specificity and sensitivity. CONCLUSION: GWR has good correlation with the MoCA and SF-36 score, and a low GWR can indicate cognitive dysfunction. In this context, GWR can be used as an additional method to evaluate cognitive function and quality of life.

The role of ultrasound in appropriate endotracheal tube size selection in pediatric patients.

BACKGROUND: The aim of this prospective study was to investigate the success of ultrasound in pediatric patients in determining the appropriate sized cuffed endotracheal tube and to compare the results with conventional height-based (Broselow) tape and age-based formula tube size. METHODS: One hundred and fifty-two children of 1-10 years of age, who received general anesthesia for adenotonsillectomy were enrolled to the study. In all participants, the transverse diameter of the subglottis was measured with ultrasound during apnea. An endotracheal tube was chosen with the outer diameter matched to the measured subglottic airway diameter. An age-based (Motoyama-Khine) and height-based (Broselow) endotracheal tube size was calculated. If there was resistance to passage of the tube into the trachea or an airway pressure >25 cmH2 0 was required to detect an audible leak, the endotracheal tube was replaced with internal diameter of 0.5 mm smaller. If there was an audible leak at airway pressure <10 cmH2 O, or peak pressure >25 cmH2 0 or a cuff pressure > 25 cmH2 O was required to seal, the tube was changed to the 0.5 mm larger internal diameter. Best-fit tube internal diameter was the resultant tube internal diameter that met the previously stated conditions. The need for endotracheal tube replacement and peak airway pressure were recorded. RESULTS: The internal diameter of ultrasound determined tube was the same as best-fit tube in 88% of children. Endotracheal tube was replaced in 15 patients with a one size larger, and in three patients with one size smaller tube. Using Bland-Altman analysis, a better agreement was observed with ultrasound measurement rather than height-based estimation and age-based formulas. CONCLUSION: Our findings show that subglottic diameter measured by ultrasound appears to be a reliable predictor for the assessment of the subglottic diameter of the airway in estimating appropriate size pediatric endotracheal tube.

Comparison of Ultrasound-Guided Axillary Brachial Plexus Block Properties in Diabetic and Nondiabetic Patients: A Prospective Observational Study.

PURPOSE: Patients with diabetes mellitus (DM) type 2 may have subclinical peripheral nerve neuropathy. We performed this study to compare the differences in duration of axillary brachial plexus blocks in patients with type 2 DM and without DM (NODM). Our hypothesis was that the sensory block duration would be prolonged in patients with DM. METHODS: A total of 71 patients who were scheduled for elective forearm and/or hand surgery were enrolled in this study. Before surgery, they received ultrasound-guided axillary brachial plexus blocks with a mixture of 10 mL lidocaine 2% and 20 mL bupivacaine 0.5%. After surgery, all patients received 1 g paracetamol every 6 hours as needed. The primary end point was sensory block duration. Secondary end points were motor block duration, time until first pain (numeric rating scale [NRS] 4 or greater), highest NRS pain scores, and rescue analgesic consumption (NRS 4 or greater) through the first 2 postoperative days. RESULTS: In all, 67 patients completed the study: 22 in the DM group and 45 in the NODM group. Sensory and motor block durations were longer in the DM group than in the NODM group (mean [range], 773.5 [479-1155] vs 375 [113-900] minutes, and 523 [205-955] vs 300 [110-680] minutes). Time until first pain was 855 (590-1,285) minutes in the DM group and 500 (200-990) minutes in the NODM group. The highest NRS scores were also significantly lower in the DM group at 6 and 12 hours. Paracetamol consumption was lower in the DM group through the first 2 postoperative days. CONCLUSIONS: The presence of DM was associated with longer duration of the sensory block after axillary brachial plexus block. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

Bispectral index dynamics during propofol hypnosis is similar in red-haired and dark-haired subjects.

BACKGROUND: We have previously shown that red hair is associated with increased desflurane requirement for immobility, compared with dark hair. The effect of red hair on IV anesthetic requirement remains unknown. We tested the hypothesis that the propofol concentration in the effect site associated with half maximal electroencephalogram response, Ce50, is at least 50% higher in subjects with red hair. METHODS: We modeled the propofol concentration versus electroencephalogram response relationship using a 2-step approach in 29 healthy dark- and red-haired volunteers receiving a propofol infusion to produce loss of consciousness. Bispectral Index (BIS) was the measure of drug effect. The parameters of a 3-compartment pharmacokinetic model were fit to measured arterial propofol concentrations. The relationship between effect-site propofol concentration (Ce) and BIS was characterized using a sigmoid Emax model. Model performance and accuracy of the estimated parameters were evaluated using accepted metrics and bootstrap resampling. The effect of hair color on the Ce50 for BIS response in the final model was assessed using a threshold of 6.63 (P<0.01) in reduction of -2 log likelihood. The influence of body weight on the model was also assessed. RESULTS: The inclusion of hair color as a model covariate did not improve either the pharmacokinetic or the pharmacodynamic model. A separate analysis for the dark- and red-haired subjects estimated a median (95% confidence interval) Ce50 BIS of 2.71 µg/mL (2.28-3.36 µg/mL) and 2.57 µg/mL (1.68-3.60 µg/mL), respectively. Body weight was a significant covariate for the CL1 and V1. CONCLUSIONS: Red hair phenotype does not affect the pharmacokinetics or pharmacodynamics of propofol.

Integration of functional capacity to medically necessary, time-sensitive scoring system: A prospective observational study.

OBJECTIVES: To evaluate 2 new modifications to medically necessary, time-sensitive (MeNTS) scoring systems integrating functional capacity assessment in estimating intensive care unit (ICU) requirements. METHODS: This prospective observational study included patients undergoing elective surgeries between July 2021 and January 2022. The MeNTS scores and our 2 modified scores: MeNTS-METs (integrated Duke activity status index [DASI] as metabolic equivalents [METs]) and MeNTS-DASI-5Q (integrated modified DASI [M-DASI] as 5 questions) were calculated. The patients' ICU requirements (group ICU+ and group ICU-), DASIs, patient-surgery-anesthesia characteristics, hospital stay lengths, rehospitalizations, postoperative complications, and mortality were recorded. RESULTS: This study analyzed 718 patients. The MeNTS, MeNTS-METs, and MeNTS-DASI-5Q scores were higher in group ICU+ than in group ICU- (p<0.001). Group ICU+ had longer operation durations and hospital stay lengths (p<0.001), lower DASI scores (p<0.001), and greater hospital readmissions, postoperative complications, and mortality (p<0.001). The MeNTS-METs and MeNTS-DASI-5Q scores better predicted ICU requirement with areas under the receiver operating characteristic curve (AUC) of 0.806 and 0.804, than the original MeNTS (AUC=0.782). CONCLUSION: The 5-questionnaire M-DASI is easy to calculate and, when added to a triage score, is as reliable as the original DASI for predicting postoperative ICU requirements.

Single and double injection paravertebral block comparison in reduction mammaplasty cases: a randomized controlled study.

BACKGROUND: This study compares the analgesic effects and dermatomal blockade distributions of single and double injection bilateral thoracic paravertebral block (TPVB) techniques in patients undergoing reduction mammaplasty. METHODS: After obtaining ethics committee approval, 60 patients scheduled for bilateral reduction mammaplasty were included in the study. Preoperatively, the patients received one of single (Group S: T3-T4) or double (Group D: T2-T3 & T4-T5) injection bilateral TPVBs using bupivacaine 0.375% 20 ml per side. All patients were operated under general anesthesia. The T3-T6 dermatomal blockade distributions on the midclavicular line were followed by pin-prick test for 30 min preoperatively and 48 h postoperatively. All patients received paracetamol 1 g when numeric rating scale (NRS) pain score was ≥ 4, and also tramadol 1 mg/kg when NRS was ≥ 4 again after 1 h. The primary endpoint was NRS pain scores at postoperative 12th h. The secondary endpoints were dermatomal blockade distributions and NRS scores through the postoperative first 48 h, time until first pain and the analgesic consumption on days 1 and 2. RESULTS: Fifty-two patients completed the study. The NRS pain scores at 12th h were similar (right side: P = 0.100, left side: P = 0.096). The remaining NRS scores and other parameters were also comparable within the groups (P ≥ 0.05). Only single injection TPVB application time was shorter (P < 0.001). CONCLUSIONS: The single injection TPVB technique provided sufficient dermatomal distribution and analgesic efficacy with the advantages of being faster and less invasive.

Epidemiology of surgery associated acute kidney injury (EPIS-AKI): a prospective international observational multi-center clinical study.

PURPOSE: The incidence, patient features, risk factors and outcomes of surgery-associated postoperative acute kidney injury (PO-AKI) across different countries and health care systems is unclear. METHODS: We conducted an international prospective, observational, multi-center study in 30 countries in patients undergoing major surgery (> 2-h duration and postoperative intensive care unit (ICU) or high dependency unit admission). The primary endpoint was the occurrence of PO-AKI within 72 h of surgery defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Secondary endpoints included PO-AKI severity and duration, use of renal replacement therapy (RRT), mortality, and ICU and hospital length of stay. RESULTS: We studied 10,568 patients and 1945 (18.4%) developed PO-AKI (1236 (63.5%) KDIGO stage 1500 (25.7%) KDIGO stage 2209 (10.7%) KDIGO stage 3). In 33.8% PO-AKI was persistent, and 170/1945 (8.7%) of patients with PO-AKI received RRT in the ICU. Patients with PO-AKI had greater ICU (6.3% vs. 0.7%) and hospital (8.6% vs. 1.4%) mortality, and longer ICU (median 2 (Q1-Q3, 1-3) days vs. 3 (Q1-Q3, 1-6) days) and hospital length of stay (median 14 (Q1-Q3, 9-24) days vs. 10 (Q1-Q3, 7-17) days). Risk factors for PO-AKI included older age, comorbidities (hypertension, diabetes, chronic kidney disease), type, duration and urgency of surgery as well as intraoperative vasopressors, and aminoglycosides administration. CONCLUSION: In a comprehensive multinational study, approximately one in five patients develop PO-AKI after major surgery. Increasing severity of PO-AKI is associated with a progressive increase in adverse outcomes. Our findings indicate that PO-AKI represents a significant burden for health care worldwide.

Evaluation of Postoperative Complication with Medically Necessary, Time-Sensitive Scoring System During Acute COVID-19 Pandemic: A Prospective Observational Study.

BACKGROUND: High scores in the Medically Necessary, Time-Sensitive (MeNTS) scoring system, used for elective surgical prioritization during the coronavirus disease 2019 pandemic, are assumed to be associated with worse outcomes. We aimed to evaluate the MeNTS scoring system in patients undergoing elective surgery during restricted capacity of our institution, with or without moderate or severe postoperative complications. STUDY DESIGN: In this prospective observational study, MeNTS scores of patients undergoing elective operations during May and June 2020 were calculated. Postoperative complication severity (classified as Group Clavien-Dindo < II or Group Clavien-Dindo ≥ II), as well as Duke Activity Index, American Society of Anesthesiologists (ASA) physical status, presence of smoking, leukocytosis, lymphopenia, elevated C-reactive protein (CRP), operation and anesthesia characteristics, intensive care requirement and duration, length of hospital stay, rehospitalization, and mortality were noted. RESULTS: There were 223 patients analyzed. MeNTS score was higher in the Clavien-Dindo ≥ II Group compared with the Clavien-Dindo < II Group (50.98 ± 8.98 vs 44.27 ± 8.90 respectively, p < 0.001). Duke activity status index (DASI) scores were lower, and American Society of Anesthesiologists physical status class, presence of smoking, leukocytosis, lymphopenia, elevated CRP, and intensive care requirement were higher in the Clavien-Dindo ≥ II Group (p < 0.01). Length of hospital stay was longer in the Clavien-Dindo ≥ II Group (15 [range 2-90] vs 4 [1-30] days; p < 0.001). Mortality was observed in 8 patients. Area under the receiver operating characteristic curve of MeNTS and DASI were 0.69 and 0.71, respectively, for predicting moderate/severe complications. CONCLUSIONS: Although significant, MeNTS score had low discriminating power in distinguishing patients with moderate/severe complications. Incorporation of a cardiovascular functional capacity measure could improve the scoring system.

Effects of short-term hyperoxic ventilation on lung, kidney, heart, and liver in a rat model: A biochemical evaluation.

BACKGROUND: Despite studies on the adverse effects of hyperoxia, its use is still recommended by the World Health Organization. The aim of this study was to test the possible harmful effects of hyperoxia on the lung, kidney, heart, and liver in a rat mechanical ventilation model. METHODS: Male Wistar rats were randomly assigned into two groups (n=6/group): Normoxic (FiO2: 0.3) or hyperoxic (FiO2: 1.0) ventilation for 4 h. The injury was evaluated in bronchoalveolar lavage (BAL), blood, lung, liver, kidney, and heart was evaluated in terms of cell surface integrity, extracellular matrix (sialic acid, syndecan-1), osmotic stress (free hemoglobin), and redox homeostasis-lipid peroxidaation (malondialdehyde). BAL and wet/dry weight ratio were also evaluated for cellular permeability. RESULTS: Four hours of hyperoxic ventilation did not lead to significant changes in (1) sialic acid, syndecan-1, (2) malondialdehyde levels and wet/dry weight ratio in liver, kidney, heart, and lung compared to normoxic ventilation. CONCLUSION: Mechanical ventilation with hyperoxia seems to have almost similar effects compared to ventilation with normoxia. However, the long term effect of hyperoxia should be evaluated.

Suppression of shivering during hypothermia using a novel drug combination in healthy volunteers.

BACKGROUND: Hypothermia may be beneficial in stroke victims; however, it provokes vigorous shivering. Buspirone and dexmedetomidine each linearly reduce the shivering threshold with minimal sedation and no respiratory depression. This study tested the hypotheses that the combination of buspirone and dexmedetomidine would (1) synergistically reduce the shivering threshold, (2) synergistically reduce the gain and maximum intensity of shivering, and (3) produce sufficient inhibition to permit cooling to 34 degrees C without excessive hypotension or sedation. METHODS: Eight healthy men were randomly assigned on 4 days to (1) no drug, (2) buspirone (60 mg orally), (3) dexmedetomidine (intravenous infusion to target plasma concentration of 0.6 ng/ml), or (4) combination of buspirone and dexmedetomidine at same doses. Lactated Ringer's solution (approximately 3 degrees C) was infused intravenously to decrease tympanic membrane temperature by 1.5 degrees C/h. Shivering threshold was defined as an increase in oxygen consumption greater than 20%. Sedation was evaluated using the Observer's Assessment of Sedation/Alertness scale. RESULTS: Mean arterial pressure and heart rate were slightly lower on dexmedetomidine and combination days. Likewise, the level of sedation was statistically different on these 2 days but clinically unimportant. Buspirone reduced the shivering threshold from 36.6 degrees C +/- 0.4 degrees C to 35.9 degrees C +/- 0.4 degrees C, dexmedetomidine reduced it to 34.7 degrees C +/- 0.5 degrees C, and the combination to 34.1 +/- 0.4 degrees C. The interaction effect of 0.04 degrees C was not significant. The gain of shivering and maximum shivering intensity were similar on each day. CONCLUSIONS: The combination of buspirone and dexmedetomidine additively reduced the shivering threshold. Thus, supplementing dexmedetomidine with buspirone blocks shivering and causes only minimal sedation.

Neuromuscular block differentially affects immobility and cortical activation at near-minimum alveolar concentration anesthesia.

BACKGROUND: Anesthesia-induced immobility and cortical suppression are governed by anatomically separate, but interacting, areas of the central nervous system. Consequently, larger volatile anesthetic concentrations are required to suppress cortical activation than to abolish movement in response to noxious stimulation. We examined the effect of decreased afferent input, as produced by neuromuscular block (NMB), on immobility and cortical activation, as measured by bispectral index (BIS) of the electrocardiogram, in the presence of noxious stimulation during approximately minimum alveolar concentrations (MACs) of desflurane anesthesia. METHODS: The effect of NMB on the median effective end-tidal concentration of desflurane (EtDes(50), or MAC(tetanus)) for immobility was estimated using the up-and-down method and isolated forearm technique in 24 healthy volunteers. Each volunteer sequentially received saline, mivacurium, and succinylcholine in a randomized order, while EtDes concentration during each of the treatments was determined based on the movement response of the previous volunteer on the same treatment. Nonlinear mixed-effects modeling was used to evaluate the effect of NMB on BIS versus EtDes concentration relationship at baseline and after noxious stimulation, while the frontal electromyogram (EMG(BIS)) effect on BIS was also modeled as a covariate. Cardiovascular responses to noxious stimulation were compared across treatments. RESULTS: Succinylcholine and mivacurium significantly reduced MAC(tetanus) (95% confidence interval) from 5.00% (4.85%-5.13%), during saline, to 4.05% (3.81%-4.29%) and 3.84% (3.60%-4.08%), respectively. Noxious stimulation significantly, although minimally, increased BIS response during all treatments. Succinylcholine increased BIS independently of an effect on EMG(BIS). Succinylcholine administration increased cardiovascular activity. Interestingly, although cardiovascular reaction to the noxious event was ablated by mivacurium, cortical response, as determined by BIS, was retained. CONCLUSIONS: Both succinylcholine and mivacurium enhanced immobility during near-MAC anesthesia. All treatments were associated with a small, although significant, BIS increase in response to noxious stimulation, whereas succinylcholine increased BIS independently of noxious stimulation or EMG(BIS). Mivacurium suppressed autonomic response to a noxious event.

Learning Curves for Two Fiberscopes in Simulated Difficult Airway Scenario With Cumulative Sum Method.

INTRODUCTION: The aims of this randomized prospective mannequin study were to determine the amount of attempts required for successful intubation using different fiberscopes (Bonfils and SensaScope) by inexperienced anesthesiologists in a difficult airway scenario and to build the associated learning curves. METHODS: Difficult airway simulation was achieved with tongue edema in mannequin. After approval of volunteers, we asked 15 anesthesiology residents without any experience with fiberscopes to intubate with each device in a random order. Intubation success (endotracheal intubation within 120 seconds), the degree of difficulty of intubation, and reality of simulation using a 10-point scale were recorded. Learning curves were generated with cumulative sum method. RESULTS: With Bonfils, 13 volunteers were able to pass lower decision boundary with a median number of 26 [95% confidence interval (CI) = 21.4-25.9] attempts, whereas in SensaScope, the same outcome was observed in 10 residents with a median number of attempts of 26 (95% CI = 23.5-32.5). Total success rate was found significantly higher with Bonfils compared with SensaScope (550/600 vs 512/600, respectively, P < 0.001). Intubation with Bonfils was considered as less difficult compared with SensaScope [median = 4 (95% CI = 3.32-4.42) and 6 (95% CI = 4.96-6.64), P = 0.01, respectively]. The reality of the simulation was rated as a median of 5 (95% CI = 4.37-5.8). CONCLUSIONS: Although a similar number of attempts were required to reach predetermined competency for both fiberscopes, only 10 of residents were able to obtain the targeted success using SensaScope as compared with 13 with Bonfils. Inexperienced residents found intubation via Bonfils less difficult than SensaScope. High individual variability in obtaining competency observed in this study with cumulative sum analysis underlines the importance of defining success a priori to simulation, the need for follow-up of individual progress, and the need to offer adequate trials to achieve competency. Therefore, learning opportunities should be adapted accordingly.

Ability of mini-fluid challenge to predict fluid responsiveness in obese patients undergoing surgery in the prone position.

BACKGROUND: Pulse pressure variation (PPV) and stroke volume variation (SVV) can predict fluid responsiveness effectively. However, high Body Mass Index (BMI) can restrict their use due to changes in respiratory system compliance (CS), intra-abdominal pressure, and stroke volume (SV) in the prone position. Therefore, we aimed to investigate the effectiveness of mini-fluid challenge (MFC) in predicting fluid responsiveness in obese (BMI ≥30 kg/m2) patients in the prone position. METHODS: A total of 33 patients undergoing neurosurgery were included. After standardized anesthesia induction, patients' PPV, SVV, stroke volume index (SVI) and CS values were recorded in the prone position (T1), after the infusion of 100 mL of crystalloid named as MFC (T2) and after fluid loading was completed with additional 400 mL of crystalloid. Patients whose SVI increased more than 15% after the fluid loading were defined as volume responders. RESULTS: Fifteen (45%) patients were responders to 500 mL fluid loading. After the 100 mL fluid load, a higher percentage increase in SVI was observed among responders (P<0.001), with values of 6.6% (6.2-8.6%) and 3.5% (1.7-4.8%) in responders and non-responders, respectively. Areas under the receiver operating characteristic curves of MFC, PPV, and SVV were 0.967 (95% CI: 0.838-0.999), 0.683 (95% CI: 0.499-0.834), and 0.709 (95% CI: 0.526-0.853), respectively. The area under the curve of MFC was significantly higher than that of PPV (P=0.003) and SVV (P=0.005). CONCLUSIONS: The increase in SVI after a rapid infusion of 100 mL crystalloid could predict fluid responsiveness in patients with BMI ≥30 kg/m2 in the prone position.

A challenge with 5 cmH2O of positive end-expiratory pressure predicts fluid responsiveness in neurosurgery patients with protective ventilation: an observational study.

BACKGROUND: Positive end-expiratory pressure (PEEP) increment induces a decrease in Stroke Volume Index (SVI). We hypothesized that the magnitude of SVI reduction due to a 5 cmH2O increase in PEEP could predict fluid responsiveness during low tidal volume ventilation. METHODS: Forty-eight patients completed the study. Heart rate, mean arterial pressure, SVI, pulse pressure variation (PPV) and stroke volume variation (SVV) were recorded before short-time low PEEP (SLPC) challenge (applied additional 5 cmH2O PEEP to patients for 30 seconds), during SLPC and before and after 500 mL fluid loading. Patients whose SVI increased more than 15% after the fluid loading were defined as volume responders. RESULTS: Twenty-one (44%) patients were volume responder. Decrease percentage in SVI during SLPC was 17.4±3.6% and 9.9±3.1% in responders and non-responders respectively (P<0.001). A strong correlation was found between decrease percentage in SVI during SLPC and increase percentage in SVI after fluid loading (R2=0.680, P<0.001). The area under receiver operating curves generated to predict fluid responsiveness for decrease percentage in SVI during SLPC (0.944, 95% CI: 0.836-0.990) was significantly higher than that for PPV (0.777, 95% CI: 0.634-0.884, P=0.025) and SVV (0.773, 95% CI: 0.630-0.882, P=0.022). Best cut-off values of decrease percentage in SVI during SLPC was -14.2 with 95% sensitivity and 89% specificity. CONCLUSIONS: SVI change percentage during SLPC can predict fluid responsiveness better than PPV and SVV in neurosurgery patients ventilated with low tidal volume.

Does supplemental oxygen reduce postoperative nausea and vomiting? A meta-analysis of randomized controlled trials.

BACKGROUND: Studies on the ability of supplemental oxygen to decrease the incidence of postoperative nausea and vomiting (PONV) are inconsistent, with initial studies suggesting benefit while subsequent trials demonstrate no decrease in PONV. METHODS: To clarify whether supplemental oxygen is an effective and reliable method to reduce PONV, we performed a systematic review (MEDLINE, Cochrane Library, hand searching and bibliographies, with no language restriction, through March 2006) of randomized, controlled trials comparing perioperative 80% versus 30%-40% Fio(2) on the incidence of PONV. For this systematic review, PONV was defined as any nausea, retching, and/or vomiting in the first 24 h after surgery. The end-points were early PONV (0-6 h), late PONV (6-24 h), and overall PONV (0-24 h). Data from 10 trials with 1729 patients were included in our meta-analysis: 860 received 80% Fio(2) and 869 received 30%-40% Fio(2). RESULTS: In patients who received 80% Fio(2),the relative risk (95% confidence intervals) of experiencing early PONV was 0.91 [0.71-1.16]; late PONV, 0.88 [0.69-1.11]; and overall PONV, 0.91 [0.77-1.06]. Results were similar for early, late, and overall nausea and vomiting. CONCLUSIONS: The positive results of two initial studies reducing the risk for PONV in patients given 80% Fio(2) were not confirmed by any of the subsequent trials. Considering all available evidence, 80% Fio(2) should no longer be considered an effective or reliable method to reduce overall PONV.

Comparison of sevoflurane and ketamine for anesthetic induction in children with congenital heart disease.

BACKGROUND: Sevoflurane is widely used in pediatric anesthesia for induction. Ketamine has been preferred in pediatric cardiovascular anesthesia. Aim of this study was to compare the hemodynamic effects and the speed of ketamine and sevoflurane for anesthesia induction in children with congenital heart disease. MATERIALS AND METHODS: Children with congenital heart disease undergoing corrective surgery were included in the study. After oral premedication with midazolam (0.5 mg.kg(-1)), anesthesia induction was started with 5 mg.kg(-1) intramuscular ketamine (group K). In the second group, induction was achieved with sevoflurane (group S); the first concentration was 3% and increased after every three breaths. Intravenous access time and intubation times were enrolled for each child. Hemodynamic data and oxygen saturation were recorded every 2 min and any event during induction period was also noted. RESULTS: Forty-seven children were included in the study; 23 in group K and 24 in group S. Heart rates and oxygen saturation values were similar between groups during the study. No difference was found between intravenous access time and intubation times. However, blood pressure levels were significantly lower in group S after recording baseline values till the intubation time (at 4, 6, and 8 min). Respiratory complications observed during the study were mild and were less frequent in group K than in group S (4 vs 13). CONCLUSION: Ketamine appears a good alternative for induction in patients with congenital heart disease. It permits preservation of hemodynamic stability with minimal side effects.