Target-Controlled Infusion for Remifentanil in Vascular Patients Improves Hemodynamics and Decreases Remifentanil Requirement

Sedation vs. general anesthesia in stone ureteroscopy: Comparison of efficacy and safety, a post COVID-19 report

INTRODUCTION

Ureterorenoscopy (URS) for ureteral or renal stones is traditionally performed under general anesthesia (GA). Sedation is an alternative to GA, allowing control of the level of consciousness, spontaneous ventilation, and faster recovery. Our aim was to compare sedation and GA for patients undergoing ureterorenoscopy. Endpoints were stone-free rate (SFR) and complication rates.

METHOD

Monocentric comparative retrospective study including all consecutive ureterorenoscopies for ureteral or renal stone. The inclusion period was dichotomized in two 6-months periods due to the COVID-19 pandemic: from January 1 to July 1, 2019 (URS under GA) and from January 1 to July 1, 2021 (URS under GA or sedation). Stone-free (SF) status was defined as the absence of stone or fragment>4mm after the first ureterorenoscopy. Complication rates were assessed according to the Satava (perioperative complications) and Clavien-Dindo (postoperative complications) classifications. Statistical analysis was performed by Chi-square test.

RESULTS

A total of 185 patients were included for a total of 206 ureterorenoscopies; 82 underwent ureterorenoscopy under GA and 103 under sedation. The median stone size was 10 [7-16] mm. In all, 150 (81%) patients had at least one intrarenal stone. The SFR was similar between the two groups (67% GA group, 69% sedation group, P=0.912). In the sedation group, the mean SFR in ureter was 83.7% vs. 92.5% in the GA group. In renal cavities, the mean SFR was 46.4% in the sedation group vs. 42.5% in the GA group. Satava grade I, IIa, and IIb complications were 5 (6%), 5 (6%), and 1 (1%) in the GA group and 6 (6%), 1 (1%), and 3 (3%) in the sedation group, respectively (P=0.214). The grade I, II, III, and IV Clavien complications were 6 (7%), 3 (4%), 0 (0%), and 2 (2%) in the GA group and 6 (6%), 4 (4%), 1 (1%), and 4 (4%) in the sedation group, respectively (P=0.928).

CONCLUSION

Our post COVID-19 study showed no difference in efficacy and safety between ureterorenoscopy under sedation and GA for patients with renal stones. Our results confirm the interest of the sedation procedure, particularly in the context of outpatient surgery.

LEVEL OF EVIDENCE: 4

Pharmacokinetic and Pharmacodynamic Changes in the Elderly: Impact on Anesthetics

Anesthesiologists are increasingly required to care for frail elderly patients. A detailed knowledge of the influence of age on the pharmacokinetics and dynamics of the anesthetic drugs is essential for optimal safety and care. For most of the anesthetic drugs, the elderly need lower doses to achieve the same plasma concentrations, and at any given plasma and effect-site concentration, they will have more profound clinical effects than younger patients. Caution is required, with close monitoring of clinical effects and active titration of dose administration to achieve the desired level of effect, ideally following the "start low, go slow" principle.

Hypobaric Unilateral Spinal Anesthesia Versus General Anesthesia for Hip Fracture Surgery in the Elderly: A Randomized Controlled Trial

BACKGROUND

Hypotension during surgery is frequent in the elderly population and is associated with acute kidney and myocardial injury, which are, themselves, associated with increased 30-day mortality. The present study compared the hemodynamic effects of hypobaric unilateral spinal anesthesia (HUSA) to general anesthesia (GA) in patients ≥70 years of age undergoing hip fracture surgery.

METHODS

We conducted a single-center, prospective, randomized study. In the HUSA group, patients were positioned with the operated hip above, and the hypobaric anesthetic solution was composed of 9 mg ropivacaine, 5 µg sufentanil, and 1 mL of sterile water. Anesthesia was adjusted for the GA group. Mean arterial pressure (MAP) was measured with a noninvasive blood pressure upper arm cuff every 3 minutes. Hypotension was treated with a bolus of ephedrine and then a continuous intravenous of norepinephrine to obtain a MAP ≥65 mm Hg. Primary outcome was the occurrence of severe hypotension, defined as a MAP <65 mm Hg for >12 consecutive minutes.

RESULTS

A total of 154 patients were included. Severe hypotension was more frequent in the GA group compared to the HUSA group (odds ratio, 5.6; 95% confidence interval, 2.7-11.7; P < .001). There was no significant difference regarding the short-term outcomes between the HUSA and GA groups: acute kidney injury (respectively, 5.1% vs 11.3%; P = .22), myocardial injury (18.0% vs 14.0%; P = .63), and 30-day mortality (2.4% vs 4.7%; P = .65).

CONCLUSIONS

HUSA leads to fewer episodes of severe intraoperative hypotension compared to GA in an elderly population undergoing hip fracture surgery.

The Effects of Remifentanil on Hemodynamic Response Attenuation After Electroconvulsive Therapy Under Sevoflurane Anesthesia

PURPOSE

We evaluated the effects of a single loading dose of remifentanil (1 μg/kg) administered as an adjunct to sevoflurane, on the duration of seizure activity, recovery times, and hemodynamic profiles, during electroconvulsive therapy.

METHODS

The patients were randomly allocated to receive sevoflurane-saline (Group SS) or sevoflurane-remifentanil (Group SR). Sevoflurane (8%) was initiated for anesthesia induction in both groups until loss of consciousness was achieved. Remifentanil was then administered to Group SR via a 1-μg/kg intravenous bolus. Patients in Group SS received saline in the same manner. Mean arterial pressure (MAP) and heart rate (HR) were recorded before anesthetic induction (T1), at the loss of consciousness (T2), and at 0, 1, 3, and 10 minutes after the electrical stimuli were completed (T3, T4, T5, and T6, respectively).

RESULTS

Compared with the baseline values, HR increased significantly in Group SS at times T2 and T4 to T6 and decreased significantly in Group SR at time T2. When the groups were compared, we found that HR decreased significantly in Group SR at T2 and T4 to T6. Compared with baseline, MAP increased in Group SS between T3 and T6, and MAP decreased in Group SR at T2 and increased at T3 to T4. Mean arterial pressure decreased to a greater extent in Group SR than in Group SS during the T2 to T6 period. There were no group differences in seizure duration or recovery time.

CONCLUSIONS

The addition of 1-μg/kg remifentanil to anesthetic induction with sevoflurane attenuated the acute hemodynamic response to electroconvulsive therapy under sevoflurane anesthesia without adversely affecting the duration of seizure activity or the recovery profile.

Effect-site concentration of remifentanil required to blunt haemodynamic responses during tracheal intubation: A randomized comparison between single- and double-lumen tubes

Objective

To investigate the effect-site concentration of remifentanil required to blunt haemodynamic responses during tracheal intubation with a single-lumen tube (SLT) or a double-lumen tube (DLT).

Methods

Patients scheduled for thoracic surgery requiring one-lung ventilation were randomly allocated to either the SLT or DLT group. All patients received a target-controlled infusion of propofol and a predetermined concentration of remifentanil. Haemodynamic parameters during intubation were recorded. The effect-site concentration of remifentanil was determined using a delayed up-and-down sequential allocation method.

Results

A total of 92 patients were enrolled in the study. The effective effect-site concentrations of remifentanil required to blunt haemodynamic responses in 50% of patients (EC₅₀) estimated by isotonic regression with bootstrapping was higher in the DLT than the SLT group (8.5 ng/ml [95% confidence interval (CI) 8.0–9.5 ng/ml] versus 6.5 ng/ml [95% CI 5.6–6.7 ng/ml], respectively). Similarly, the effective effect-site concentrations of remifentanil in 95% of patients in the DLT group was higher than the SLT group (9.9 ng/ml [95% CI 9.8–10.0 ng/ml] versus 7.0 ng/ml [95% CI 6.9–7.0 ng/ml], respectively).

Conclusions

This study demonstrated that a DLT requires a 30% higher EC₅₀ of remifentanil than does an SLT to blunt haemodynamic responses during tracheal intubation when combined with a target-controlled infusion of propofol.

Trial registration

Clinicaltrials.gov identifier: NCT01542099.

Hemodynamic Effects of Co-administration of Midazolam during Anesthesia Induction with Propofol and Remifentanil in Hypertensive Patients

Objectives Propofol, midazolam and remifentanil are commonly used for clinical anesthesia. We compared the effects of midazolam-propofol-remifentanil and propofol-remifentanil on hemodynamic responses during anesthesia induction in hypertensive patients. Methods Seventy-six hypertensive patients with ASA II-III were assigned to receive midazolam-propofol (group MP; n = 38) or propofol (group P; n = 38). Anesthesia was induced with midazolam 0.03 mg/kg (group MP) or saline 0.03 ml/kg (group P). After two minutes, propofol 1.0 mg/kg (group MP) or 1.5 mg/kg (group P) i.v. bolus was administered. Simultaneously, 4 ng/ml of remifentanil target controlled infusion (TCI) was administered in both groups. Anesthesia was maintained using sevoflurane and 2 ng/ml of remifentanil TCI. Systolic, diastolic, and mean blood pressure (SBP, DBP, and MBP) and heart rate (HR) were measured before induction, 2 min after midazolam or normal saline, 2 min after propofol, 1 min after rocuronium, and immediately, 1 min, 2 min, and 3 min after intubation. Results SBP, DBP, and MBP decreased after propofol administration and increased immediately after intubation in both groups ( P &lt; 0.05). After intubation, SBP, DBP, and MBP decreased more than baseline values in either group. Although the overall BP of Group P was lower than that of Group MP, there were no significant differences except for SBP at 2min after intubation ( P &lt; 0.05). HR was no significant difference in either group. Conclusion Our results suggest that midazolam-propofol-remifentanil has similar hemodynamic effect with propofol-remifentanil during anesthesia induction in hypertensive patients.

Fiber optic bronchoscopy and remifentanil target-controlled infusion in critically ill patients with acute hypoxaemic respiratory failure: A descriptive study

INTRODUCTION

Sedation optimizes patient comfort and ease of execution during fiber optic bronchoscopy (FOB). Our objective was to describe the safety and efficacy of remifentanil-TCI during FOB in non-intubated, hypoxaemic, thoracic surgery ICU patients.

METHODS

Consecutive spontaneously breathing adults requiring FOB after thoracic surgery were included if they had hypoxaemia (PaO₂/FiO₂<300mmHg or need for non-invasive ventilation [NIV]) and prior FOB failure under topical anaesthesia. The remifentanil initial target was chosen at 1ng/mL brain effect-site concentration (Cet), then titrated to 0.5ng/mL Cet increments according to patient comfort and coughing. Outcomes were patient-reported pain and discomfort (Visual Analogue Scale scores), ventilatory support intensification within 24hours after bronchoscopy, and ease of FOB execution.

RESULTS

Thirty-nine patients were included; all had a successful FOB. Their median PO₂/FiO₂ before starting FOB was 187±84mmHg and 24 patients received NIV. Median [interquartile range] pain scores were not different before and after FOB (1.0 [0.0-3.0] and 0.0 [0.0-2.0], respectively). Discomfort was reported as absent or minimal by 27 patients (69%; 95% confidence interval [95% CI], 54-81%) and as bothersome but tolerable by 12 patients (31%; 95% CI, 19-46%). Mean FiO₂ returned to baseline within 2hours after FOB in 30 patients; the remaining 9 patients (23%; 95% CI, 13-38%) received ventilatory support intensification. Ease of execution was good or very good in 34 patients (87%; 95% CI, 73-94%), acceptable in 4 patients, and poor in 1 patient (persistent cough).

CONCLUSION

Sedation with remifentanil-TCI during FOB with prior failure under topical anaesthesia alone was effective and acceptably safe in non-intubated hypoxaemic thoracic surgery patients.

A survey of the intravenous sedation status in one provincial dental clinic center for the disabled in Korea

Background

The objective of the present study was to examine the status of patients who had received dental treatment under intravenous (IV) sedation at Chungnam Dental Clinic for the Disabled in Korea from its inception to the present time, and to review the analysis results.

Methods

Retrospective analysis was performed on 305 cases of patients who had received dental treatments under IV sedation between January 2011 and May 2016. The analysis examined the patient's sex, age, primary reason for IV sedation, duration of anesthesia and dental treatment, type of dental treatment performed, number of clinical departments involved in the dental treatment and level of multidisciplinary cooperation, and annual trends.

Results

Most dental treatments using intravenous sedation were performed on medically disabled patients or dentally disabled patients with an extreme gag reflex or dental phobia. The mean duration of IV sedation was 72.5 min, while the mean duration of treatment was 58.0 min. The types of dental treatments included surgical treatment (n = 209), periodontal treatment (n = 28), prosthodontic treatment (n = 28), restorative treatment (n = 23), implant surgery (n = 22), endodontic treatment (n = 9), reduction of temporomandibular joint dislocation (n = 1), and treatment of traumatic injuries (n = 1), with treatments mostly performed on adult patients.

Conclusions

With increasing demand for minimally painful treatment, cases using IV sedation are on an upward trend and are expected to continue to increase.

Remifentanil-acute opioid tolerance and opioid-induced hyperalgesia: a systematic review

The use of opioids may seem to be a double-edged sword; they provide straight analgesic and antihyperalgesic effects initially, but subsequently are associated with the expression of acute opioid tolerance (AOT) and opioid-induced hyperalgesia (OIH) that have been reported in experimental studies and clinical observations. It has been suggested that opioids can induce an acute tolerance and hyperalgesia in dose- and/or time-dependent manners even when used within the clinically accepted doses. Recently, remifentanil has been used for pain management in clinical anesthesia and in the intensive care units because of its rapid onset and offset. We reviewed articles analyzing AOT and/or OIH by remifentanil and focused on the following issues: (1) evidence of remifentanil inducing AOT and/or OIH and (2) importance of AOT and/or OIH in considering the reduction of remifentanil dosage or adopting preventive modulations. Twenty-four experimental and clinical studies were identified using electronic searches of MEDLINE (PubMed, Ovid, Springer, and Elsevier). However, the development of AOT and OIH by remifentanil administration remains controversial. There is no sufficient evidence to support or refute the existence of OIH in humans.

Pharmacokinetic-pharmacodynamic relationship of anesthetic drugs: from modeling to clinical use

Anesthesia is a combination of unconsciousness, amnesia, and analgesia, expressed in sleeping patients by limited reaction to noxious stimulations. It is achieved by several classes of drugs, acting mainly on central nervous system. Compared to other therapeutic families, the anesthetic drugs, administered by intravenous or pulmonary route, are quickly distributed in the blood and induce in a few minutes effects that are fully reversible within minutes or hours. These effects change in parallel with the concentration of the drug, and the concentration time course of the drug follows with a reasonable precision mathematical models based on the Fick principle. Therefore, understanding concentration time course allows adjusting the dosing delivery scheme in order to control the effects.   The purpose of this short review is to describe the basis of pharmacokinetics and modeling, the concentration-effects relationship, and drug interactions modeling to offer to anesthesiologists and non-anesthesiologists an overview of the rules to follow to optimize anesthetic drug delivery.

Target-Controlled Infusion of Remifentanil Without Muscle Relaxants Allows Acceptable Surgical Conditions During Thoracotomy Performed Under Sevoflurane Anesthesia

OBJECTIVES

To test the hypothesis that the use of a nonmuscle relaxant anesthetic technique (NMRT) during thoracotomy would be associated with comparable surgical conditions with the standard use of neuromuscular blocking drugs.

DESIGN

A prospective, randomized, single-blind, controlled study.

SETTING

A single university hospital.

PARTICIPANTS

Sixty-six patients scheduled for open thoracotomy under sevoflurane anesthesia with a target-controlled infusion (TCI) of remifentanil.

INTERVENTIONS

After ethical approval, patients were randomly assigned to receive cisatracurium or saline (n = 33 for each group) during the entire study period.

MEASUREMENTS AND MAIN RESULTS

The four-point ordinal surgical rating scale, the intubating conditions, the use of anesthetics and vasopressors, the incidence of light anesthesia (defined as an episode with state entropy values that exceeded 50 and/or mean arterial blood pressure and heart rate values that exceeded the baseline by 20% and lasted for more than 3 consecutive minutes), and the times to clinical recovery and postanesthesia care unit (PACU) discharge, hospital stays, and postoperative residual curarization (PORC) were recorded. Compared with the use of cisatracurium, the use of NMRT resulted in comparable good-to-excellent surgical rating scales (90.9% v 94.0%, respectively; p = 0.642), good-to-excellent laryngoscopy and endobronchial intubating conditions (93.9% v 100%, respectively; p>0.09), use of anesthetic and vasopressor medications, and hospital stays, together with shorter clinical recovery, extubation times (7.6 [95% CI 6.82 to 8.39] v 19.0 [95% CI 15.76 to 22.23] minutes, respectively; p<0.001), and PACU stays (37.4 [95% CI 35.09 to 39.79] v 70.9 [95% CI 56.90 to 84.91] minutes, respectively; p<0.001). The use of cisatracurium resulted in a nonstatistical number of light anesthesia episodes upon positioning, skin incision, and rib separation (p>0.624, with Fisher's exact test). There were no failed intubations in the 2 groups. No patient received cisatracurium in the NMRT group. Two patients (6.1%) in the cisatracurium group experienced PORC that required tracheal intubation in the PACU.

CONCLUSION

The use of TCI of remifentanil with NMRT offers acceptable laryngoscopy, intubating, and surgical conditions during sevoflurane anesthesia for open thoracotomy, especially when. the anesthesiologists have more than 10 years' experience.

Conscious sedation for awake fibreoptic intubation: a review of the literature

PURPOSE

Awake fibreoptic intubation (AFOI) is the gold standard of management of the predicted difficult airway. Sedation is frequently used to make the process more tolerable to patients. It is not always easy to strike a balance between patient comfort and good intubating conditions on the one hand and maintaining ventilation and a patent airway on the other. In the last 30 years, many drugs and drug combinations have been described, but there is very little in the literature to help guide the practitioner to choose between them. The objective of this article is to discuss the evidence supporting the use of the agents described with regard to their efficacy, recommended doses and techniques, and limitations to their use for AFOI.

SOURCE

Publication databases were searched for articles published from 1996 to 2012 relating to sedation for AFOI.

PRINCIPLE FINDINGS

Benzodiazepines, propofol, opioids, alpha2-adrenoceptor agonists, and ketamine are the main classes of drugs that have been described to facilitate AFOI. Drugs that are most suitable have a combination of both anxiolytic and analgesic properties. The ideal choice of drug may vary depending on the patient and the indication for AFOI.

CONCLUSION

There is good evidence to support the use of two drugs in particular, remifentanil and dexmedetomidine. Each has certain unique characteristics that make them an attractive choice for an AFOI.

Usefulness of Intravenous Anesthesia Using a Target-controlled Infusion System with Local Anesthesia in Submuscular Breast Augmentation Surgery

Background

Patients have anxiety and fear of complications due to general anesthesia. Through new instruments and local anesthetic drugs, a variety of anesthetic methods have been introduced. These methods keep hospital costs down and save time for patients. In particular, the target-controlled infusion (TCI) system maintains a relatively accurate level of plasma concentration, so the depth of anesthesia can be adjusted more easily. We conducted this study to examine whether intravenous anesthesia using the TCI system with propofol and remifentanil would be an effective method of anesthesia in breast augmentation.

Methods

This study recruited 100 patients who underwent breast augmentation surgery from February to August 2011. Intravenous anesthesia was performed with 10 mg/mL propofol and 50 µg/mL remifentanil simultaneously administered using two separate modules of a continuous computer-assisted TCI system. The average target concentration was set at 2 µg/mL and 2 ng/mL for propofol and remifentanil, respectively, and titrated against clinical effect and vital signs. Oxygen saturation, electrocardiography, and respiratory status were continuously measured during surgery. Blood pressure was measured at 5-minute intervals. Information collected includes total duration of surgery, dose of drugs administered during surgery, memory about surgery, and side effects.

Results

Intraoperatively, there was transient hypotension in two cases and hypoxia in three cases. However, there were no serious complications due to anesthesia such as respiratory difficulty, deep vein thrombosis, or malignant hypertension, for which an endotracheal intubation or reversal agent would have been needed. All the patients were discharged on the day of surgery and able to ambulate normally.

Conclusions

Our results indicate that anesthetic methods, where the TCI of propofol and remifentanil is used, might replace general anesthesia with endotracheal intubation in breast augmentation surgery.

Flexible fiberoptic bronchoscopy and remifentanil target-controlled infusion in ICU: a preliminary study

PURPOSE

Flexible fiberoptic bronchoscopy (FFB) is a major diagnostic tool commonly used in intensive care unit (ICU). However, it generates discomfort and pain and can worsen respiratory and/or hemodynamic condition of critically ill patients. Remifentanil is an ultrashort-acting opioid drug that has been shown to provide effective sedation for painful procedures in spontaneous breathing patients. The aim of this study is to evaluate the safety and efficacy of sedation with remifentanil target-controlled infusion (Remi-TCI) in patients with spontaneous ventilation undergoing FFB in ICU.

METHODS

Monocentric prospective study. All patients received Remi-TCI with initial effect-site target concentration of 2 ng/mL, progressively titrated according to their comfort and sedation. Respiratory and hemodynamic parameters were assessed before, during, and after the procedure, as well as comfort, level of sedation, FFB conditions, and recovery patterns. Global Remi-TCI data and potential complications of the procedure were also recorded.

RESULTS

Fourteen patients were included. FFB was successful in all patients with good conditions (sedation, global comfort, and cough). No severe hemodynamic or respiratory complications occurred during procedure. Maximum target concentration and total dose of remifentanil were 2.5 ng/mL (2-4 ng/mL) and 1.4 μg/kg (0.7-2.4 μg/kg), respectively, over 10 min. Patients reported low level of pain and good satisfaction with the procedure.

CONCLUSIONS

FFB under sedation with Remi-TCI seems to be safe and effective in critically ill patients with spontaneous ventilation. Such results could be the first step towards wider use of Remi-TCI in patients experiencing awkward and/or painful procedures in this setting.

The cardiovascular effects of midazolam co-induction to propofol for induction in aged patients

BACKGROUND

The aim of this study was to investigate whether a small dose of midazolam and lessening the propofol dosage could prevent cardiovascular change at tracheal intubation for induction in aged patients.

METHODS

Eighty patients over 65 years (ASA physical status 1, 2) scheduled for elective surgery received general anesthesia with remifentanil and propofol or midazolam. Patients in group P (n = 40) were induced with 0.9% NaCl 0.03 ml/kg, propofol 1. 2 mg/kg and remifentanil. Patients in group MP (n = 40) were induced with midazolam 0.03 mg/kg, propofol 0.8 mg/kg and remifentanil. The time taken to reach loss of consciousness (LOC) and the value of bispectral index score (BIS) at LOC were recorded. After LOC, 0.8 mg/kg of rocuronium was given and tracheal intubation was performed. The mean blood pressure (MBP) and heart rate (HR) were recorded before induction as the base value, before intubation, immediately post-intubation and 3 minutes after intubation.

RESULTS

Compared with the base values, MBP at before intubation and 3 minutes after intubation was significantly decreased in group P and group MP (P < 0.05). Compared with group P, the decrease of MBP was significantly less at before intubation, immediately after intubation and 3 minutes after intubation in group MP (P < 0.05). The time taken to reach LOC was significantly decreased in group MP compared with that in group P (P < 0.05). There were no significant differences of HR at any time between the two groups.

CONCLUSIONS

Co-induction with midazolam and propofol could prevent a marked BP decrease at tracheal intubation for induction in aged patients.

Low-dose remifentanil to modify hemodynamic responses to tracheal intubation: comparison in normotensive and untreated/treated hypertensive Korean patients

Background

Remifentanil has been shown to be effective at treating potentially adverse hemodynamic responses to tracheal intubation even at low doses (< 1 µg/kg/min), which needs to be evaluated in patients with diverse cardiovascular conditions.

Methods

A low-dose regimen of remifentanil (continuous infusion of 0.1 µg/kg/min, preceded by 0.5 µg/kg bolus) was given before induction with bolus propofol and rocuronium, and heart rate as well as systolic, diastolic, and mean arterial pressures were measured at 1 min intervals from before induction to 5 min after tracheal intubation in normotensive patients, untreated hypertensive patients, and patients with known hypertension.

Results

The low-dose regimen of remifentanil resulted in parallel hemodynamic responses in all three groups, and was effective at limiting hemodynamic responses to tracheal intubation without excessive cardiovascular depression. Hemodynamic responses in our study showed a similar pattern to that reported in previous investigations, except for elevations in heart rate and arterial pressures over the baseline values immediately after intubation.

Conclusions

We suggest that the low-dose regimen of remifentanil in our study could be routinely used to modify hemodynamic responses to tracheal intubation in patients with diverse hemodynamic characteristics. However, the development of supplementary regimens is still needed to control the brief, but exaggerated responses to tracheal intubation, especially in untreated hypertensive patients.

[An awake fiberoptic intubation protocol: descriptive retrospective assessment of safety and efficacy]

BACKGROUND AND OBJECTIVE

Flexible fiberoptic intubation of the trachea is emphasized in guidelines on the management of difficult airway. The aim of this study was to analyze the efficacy and safety of our tertiary hospital's awake fiberoptic intubation protocol.

MATERIAL AND METHODS

For retrospective descriptive study we collected information on all fiberoptic intubations performed on awake patients in the 3 years after a specific protocol was implemented. The protocol's key points focus on operating room arrangement, required staff, and sedation before the procedure. Data gathered included demographic variables, patients' diseases, preanesthetic assessment of potential difficult airway, adherence to the protocol, medication administered, and complications recorded.

RESULTS

In the course of the study, 634 fiberoptic intubations were performed; 473 patients (74.6%) had at least 1 risk factor for aspiration and 232 patients (36.5%) had at least 1 type of cardiovascular comorbidity. Difficult intubation was expected in 67%. In 99%, remifentanil was administered via target controlled infusion with a mean effect concentration of 2.9 ng/mL. The operating room arrangement and staffing protocol was followed in all cases. No pulmonary or hemodynamic complications occurred during fiberoptic intubation or immediately after surgery.

CONCLUSION

Our hospital's protocol was followed in all cases and no post-implementation complications were detected.

Automated anesthesia

PURPOSE OF REVIEW

Anesthesiologists are overloaded with information and multitasking necessities in an extremely complex work environment. The purpose of this review is to present recent developments toward automated anesthesia and present future technologies for everyday clinical practice.

RECENT FINDINGS

Decision support systems integrate different parameters, clinical scenarios and assessments by (non)-trained personnel into algorithms, which lead to diagnostic suggestions, triage evaluations or treatment options. Target-controlled anesthesia infusion systems reduce the anesthesiologist's workload; target-controlled analgesia systems have the potential to provide more stable hemodynamic control. Closed-loop delivery of anesthesia is feasible and provides anesthetic control as good as or better than human delivery. Teleanesthesia offers the possibility of distant preoperative assessment of the patient's fitness for anesthesia, aid of trained personnel to perform anesthetic tasks and the control of anesthesia delivery in a distant location.

SUMMARY

Decision support systems help to make reliable and standardized decisions in complex environments. Target-controlled infusion systems reduce the anesthetic workload. Closed-loop systems will automate anesthesia care in the near future. Teleanesthesia offers the opportunity to provide safe anesthetic care whenever trained personnel are not available or need support.

Wake-up test decrease shunts insertion during carotid endarterectomy under general anesthesia

OBJECTIVE

The use of locoregional anesthesia versus general anesthesia (GE) in carotid endarterectomy (CEA) has been a debatable issue in clinical studies for the past several years. In our study, GE with wake-up tests (WUTs) during carotid cross-clamping was used instead of stump pressure (SP) to directly assess the neurological status of the patient to determine whether shunting was needed. Our study assessed the percentage of patients under light sedation and mechanically ventilated needing shunting based on WUT compared to a systolic stump pressure (SPs) cutoff value of <or=40 mm Hg.

DESIGN

Retrospective, observational study.

SETTING

University hospital clinic.

PARTICIPANTS

Three hundred fifty-one patients (American Society of Anesthesiologists physical class II-III) with carotid artery stenosis scheduled for CEA under GE.

INTERVENTIONS

The WUT was used to assess the neurological status in patients undergoing CEA, which involved the gradual reduction of depth of anesthesia until the patient was capable of responding to a verbal stimulus and provide full collaboration while only receiving remifentanil. A positive WUT indicated that patient was not able to carry out the order.

MEASUREMENTS AND MAIN RESULTS

Of 343 patients, 20 (5.8%) were shunted due to a positive WUT after cross-clamping in comparison to 45 patients (12.8%) based on the SPs <or=40 mm Hg criteria.

CONCLUSION

Wake-up test can be used to directly assess the neurological status in patients undergoing CEA to determine whether shunting is required. Our results showed that less patients required shunting based on WUT compared to the SP criteria.

Population pharmacokinetics of landiolol hydrochloride in healthy subjects

Landiolol hydrochloride is a newly developed cardioselective, ultra short-acting beta(1)-adrenergic receptor blocking agent used for perioperative arrhythmia control. The objective of this study was to characterize the population pharmacokinetics of landiolol hydrochloride in healthy male subjects. A total of 420 blood concentration data points collected from 47 healthy male subjects were used for the population pharmacokinetic analysis. NONMEM was used for population pharmacokinetic analysis. In addition, the final pharmacokinetic model was evaluated using a bootstrap method and a leave-one-out cross validation method. The concentration time course of landiolol hydrochloride was best described by a two-compartment model with lag time. The final parameters were total body clearance (CL: 36.6 mL/min/kg), distribution volume of the central compartment (V1: 101 mL/kg), inter-compartmental clearance (16.1 mL/min/kg), distribution volume of the peripheral compartment (55.6 mL/kg), and lag time (0.82 min). The inter-individual variability in the CL and V1 were 21.8% and 46.3%, respectively. The residual variability was 22.1%. Model evaluation by the two different methods indicated that the final model was robust and parameter estimates were reasonable. The population pharmacokinetic model for landiolol hydrochloride in healthy subjects was developed and was shown to be appropriate by both bootstrap and leave-one-out cross validation methods.

Effects of maintaining a remifentanil infusion on the recovery profiles during emergence from anaesthesia and tracheal extubation

BACKGROUND

Emergence from anaesthesia and tracheal extubation can be associated with hyperdynamic circulatory responses. We examined the effects of maintaining a remifentanil infusion on recovery profiles such as coughing and cardiovascular responses after general anaesthesia.

METHODS

Forty patients undergoing endoscopic sinus surgery under general anaesthesia using total i.v. anaesthesia (propofol and remifentanil) were randomly allocated to a control group (n=20) or remifentanil group (n=20) during emergence from anaesthesia. At the end of surgery, propofol was ceased and the infusion of remifentanil was stopped in the control group and maintained in the remifentanil group at a target organ concentration of 1.5 ng ml(-1) until extubation. Heart rate (HR), mean arterial pressure (MAP), and recovery profiles were measured and evaluated.

RESULTS

There was no significant difference in sex ratio, age, weight, height, time to eye opening, time to extubation, nausea, visual analogue scale, and time to discharge. Increases in HR and MAP occurred during emergence in the control group compared with baseline values. Increases in HR were attenuated in the remifentanil group and MAP decreased during recovery compared with baseline values. HR and MAP values were significantly higher in the control group [103 (23) beats min(-1), 129 (17) mm Hg] compared with the remifentanil group [79 (17) beats min(-1), 112 (15) mm Hg] during emergence and tracheal extubation. Moderate or severe coughing was observed only in the control group (8/20 vs 0/20, P<0.001).

CONCLUSIONS

Maintaining a remifentanil infusion reduced haemodynamic changes and coughing associated with tracheal extubation almost without significantly delaying recovery from anaesthesia.

Adequate sevoflurane concentrations in inhalation induction of sevoflurane following administration of remifentanil

BACKGROUND

Currently, sevoflurane and remifentanil are utilized frequently for the inhalation induction of anesthesia. However, there is currently an insufficient amount of clinical data regarding the inhalation induction of sevoflurane after the administration of remifentanil.

METHODS

80 patients undergoing elective surgery were allocated randomly to four groups. Group A inhaled only sevoflurane at 8 vol%. Other groups were administered 3 ng/ml of remifentanil and inhaled sevoflurane at 8 vol% (group B) or 6 vol% (group C) or 4 vol% (group D). All groups also received 0.6 mg/kg of rocuronium. The blood pressure and heart rate were measured at pre-induction, and before and after tracheal intubation. After operation, the patients??levels of satisfaction with the inhalation induction were evaluated.

RESULTS

The time to loss of consciousness was substantially longer in group D than in the other groups, but no significant differences were noted among the groups in terms of satisfaction scores. The HR in groups B, C and D increased significantly after pre-intubation as compared to baseline in group A. The HR decreased significantly during induction as compared to group A. The MAP in groups B, C and D decreased significantly at 1 and 2 minutes after tracheal intubation as compared to group A. In group D only, we noted no significant differences in the MAP as compared to baseline at 1, 2 minutes after tracheal intubation.

CONCLUSIONS

4 vol% sevoflurane was a more appropriate concentration for the inhalation induction of anesthesia when coupled with 3 ng/ml of remifentanil.

The effects of midazolam and remifentanil on induction of anesthesia and hemodynamics during tracheal intubation under target-controlled infusion of propofol

BACKGROUND

The combined induction using two or more agents has a potential benefit that anesthesia could be induced with smaller anesthetic agents with fewer side effects. We studied the effects of co-administration with midazolam and remifentanil on the dose of propofol, the time to loss of consciousness (LOC) and hemodynamics during tracheal intubation.

METHODS

Sixty patients were randomly assigned to three groups. Group 1 was induced with target-controlled propofol alone. Group 2 received midazolam (0.05 mg/kg) and target-controlled propofol. Group 3 received midazolam (0.025 mg/kg), remifentanil (2 ng/ml) and target-controlled propofol. The time to LOC, the infused propofol dose and the effect site concentration at LOC were recorded. After LOC, rocuronium (0.6 mg/kg) was given and tracheal intubation was performed. The noninvasive blood pressure, heart rate (HR) and bispectral index were recorded.

RESULTS

The time and the dose of propofol to LOC were significantly reduced in group 2, 3 than in group 1 (P < 0.05). Compared with pre-induction values, mean blood pressure at immediately after intubation was increased in group 1, 2 with no change in group 3. The HR immediately after intubation was significantly increased in all groups compared to the pre-induction values, but the rate of increase of HR in group 3 were significantly lower than those group 1, 2 (P < 0.05).

CONCLUSIONS

The co-administration with midazolam and remifentanil reduces the time to LOC and the dose of propofol. That also attenuates hemodynamics during tracheal intubation under target-controlled infusion of propofol.

The optimal effect site concentration of remifentanil for tracheal intubation without muscle relaxant during inhalation anesthetic induction using sevoflurane in adult

BACKGROUND

Sevoflurane has been shown to be suitable for inhalation induction of anesthesia in adults. The addition of remifentanil during sevoflurane induction allows for rapid and smooth tracheal intubation without muscle relaxant. The high concentration of remifentanil can result in improved conditions for tracheal intubation but also caused a cardiovascular instability. We tried to estimate optimal effect site concentration of remifentanil for tracheal intubation without muscle relaxants during inhalation anesthetic induction with 8 vol% sevoflurane and 50% N2O.

METHODS

One hundred five ASA I and II patients were randomly allocated to receive an effect site concentration of remifentanil 2, 4, or 6 ng/ml. Trachea was intubated without muscle relaxant after 3 minutes of inhalation induction with 8 vol% sevoflurane and 50% N2O. The intubating conditions for tracheal intubation were assessed and blood pressure and heart rate were recorded at the baseline, before intubation, just after intubation, 1, and 3 minute after intubation.

RESULTS

Tracheal intubation was successful in all patients. Clinically acceptable intubation conditions were 60%, 94%, and 100% in 2 ng/ml, 4 ng/ml, and 6 ng/ml group respectively. However, the number of patient who requested rescue medication for bradycardia in 6 ng/ml group was significantly higher than that in the other group (P < 0.05).

CONCLUSIONS

We concluded that 4 ng/ml effect site concentration of remifentanil is adequate concentration for tracheal intubation without muscle relaxants during inhalation induction using sevoflurane.

Effect-site concentration of remifentanil for laryngeal mask airway insertion during target-controlled infusion of propofol

The purpose of this study was to determine the effect-site concentration of remifentanil that would provide optimal conditions for successful laryngeal mask airway insertion during a target-controlled infusion (TCI) of propofol at 3.5 microg.ml(-1) without the use of neuromuscular blockade. Five minutes after propofol infusion, remifentanil was infused at a dose determined by a modified Dixon's up-and-down method. Five minutes after remifentanil infusion, the laryngeal mask was inserted. The effect-site concentration of remifentanil for successful laryngeal mask insertion in 50% of adults (EC(50)) was 3.04 (SD 0.49) ng.ml(-1) during a TCI of 3.5 microg.ml(-1) propofol without neuromuscular blockade. From the probit analysis, the EC(50) and EC(95) of remifentanil were 2.84 ng.ml(-1) (95% CI 2.09-3.57 ng.ml(-1)) and 3.79 ng.ml(-1) (95% CI 3.26-9.25 ng.ml(-1)), respectively.

[Target-controlled infusion (TCI) - a concept with a future?: state-of-the-art, treatment recommendations and a look into the future]

Over the last 10 years the technique of target-controlled infusion (TCI) has substantially influenced the development and practice of intravenous anaesthesia. It opened the possibility of many new and exciting applications of perioperative anaesthetic care. More recent and current developments, such as open TCI (target-controlled infusion) and the availability of generic anaesthetic agents combined with modern infusion pumps, means that TCI can become a standard procedure in anaesthesia and is no longer just a research tool for specialists and enthusiasts. This review explains the fundamentals and applications of intravenous drug delivery by TCI and gives practice guidelines to successfully implement the technique into clinical practice. The aim is to provide a comprehensive reference based on clinically proven evidence.

Remifentanil-TCI and propofol-TCI for conscious sedation during fibreoptic intubation in the acromegalic patient

BACKGROUND AND OBJECTIVE

To evaluate the use of remifentanil-propofol administered as target-controlled infusion during awake fibreoptic intubation for anticipated difficult tracheal intubation in acromegalic patients.

METHOD

In all, 20 consecutive acromegalic patients underwent elective endonasal endoscopic transsphenoidal pituitary surgery. After premedication with midazolam 0.03 mg kg(-1), initially a target-controlled infusion of remifentanil 1.0 ng mL(-1) and propofol 1.5 microg mL(-1) was started. The fibreoptic intubation was performed by the same physician experienced with the fibreoptic technique. During the fibreoptic procedure the target concentrations of remifentanil and propofol ranged between 1.0 and 5.0 ng mL(-1), and between 1.5 and 3.5 microg mL(-1), respectively. Changes in heart rate and mean arterial pressure were recorded during airway manipulation, during tracheal intubation, and at 1 and 3 min after. On the first postoperative day, patient recall and level of discomfort during fibreoptic intubation were evaluated.

RESULTS

Endotracheal intubation was efficaciously and quickly secured in all patients. A significant increase in mean arterial pressure and heart rate was recorded only during tracheal intubation (P < 0.05). Oxygenation was sufficient and no bradypnea or apnoea was recorded. All patients later described their anaesthetic experience as satisfactory. During fibreoptic intubation, remifentanil (ng mL(-1)) and propofol (microg mL(-1)) mean effect-site concentrations were 3.2 +/- 0.3 and 2.0 +/- 1.0, respectively.

CONCLUSION

Remifentanil and propofol target-controlled infusion provided satisfactory conscious sedation allowing for successful oral fibreoptic intubation in acromegalic patients with no recall.