[Target-controlled intravenous anesthesia]

Laryngeal microsurgery under Transnasal Humidified Rapid Insufflation Ventilatory Exchange

Objective

Since 2015, Transnasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) has been used in general anesthesia for preoxygenation or difficult exposure airway management. Its use offers new opportunities in laryngology. THRIVE increases apnea time and frees the access to the upper airway. However, its use may be less stable than orotracheal intubation. The main objective of this work was to evaluate the feasibility of laryngeal microsurgery under THRIVE including using Laser.

Study Design

Retrospective.

Setting

A total of N = 99 patients with laryngeal microsurgery (with or without CO2 laser) under THRIVE were included successively from January 1, 2020 to January 30, 2022.

Method

Medical history, comorbidities, clinical and surgical data were extracted and analyzed. Two groups were constituted regarding the "success" (use of THRIVE along all the procedure) or the "failure" (need for an endotracheal tube) of the use of THRIVE during the procedure.

Results

A failure occurred in N = 15/99 patients (15.2%) mainly due to refractory hypoxia. The odd ratios (OR) for THRIVE failure were: OR = 6.6 [2.9-35] for overweight (BMI >25 kg/m2); OR = 3.8 [1.7-18.7] for ASA score >2; OR = 4.7 [2.3-24.7] for the use of CO2 laser. Elderly patients and patients with pulmonary pathology were not statistically at greater risk of THRIVE failure. No adverse event was described.

Conclusion

This work confirms the feasibility of laryngeal microsurgery under THRIVE, including with CO2 laser. Overweight, ASA >2 and lower fraction of inspired oxygen during CO2 laser use increased the risk for orotracheal intubation.

Anesthesia for endoscopic retrograde cholangiopancreatography: target-controlled infusion versus standard volatile anesthesia

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) is a technique used both for diagnosis and for the treatment of biliary and pancreatic diseases. ERCP has some anesthetic implications and specific complications. The primary outcome aim was to compare two protocols in terms of time of extubation. We also compared anesthetic protocols in terms of hemodynamic and respiratory instability, antispasmodics needs, endoscopist satisfaction, and recovery room stay.

METHODS

Patients were randomized into two groups standard anesthesia group (Gr: SA) in whom induction was done by propofol, fentanyl and cisatracurium and maintenance was done by a mixture of oxygen, nitrousoxide (50%:50%) and sevoflurane; and intravenous anesthesia group to target concentration (Gr: TCI) in whom induction and maintenance of anesthesia were done with propofol with a target 0.5-2 μg/mL, and remifentanil with a target of 0.75-2 ng/mL.

RESULTS

90 patients were included. Extubation time was shorter in Gr: TCI, 15±2.6 vs. 27.4±7.1 min in Gr: SA (P<0.001). The incidence of hypotension was higher in GrL: SA (P=0.009). Satisfaction was better in Gr: TCI (P=0.003). Antispasmodic need was higher in Gr: SA (P=0.023). Six patients in Gr: SA group had desaturation in post-anesthesia care unit (PACU) versus one patient from Gr: TCI (P=0.049). Patients in Gr: TCI had shorter PACU stay 40.2±7.3 vs. 58.7±12.4 min (P<0.001).

CONCLUSION

The use of TCI mode allows better optimization of general anesthesia technique during ERCP.

Comparison of the Effect of Anesthesia With Midazolam-Fentanyl Versus Propofol-Remifentanil on Bispectral Index in Patients Undergoing Coronary Artery Bypass Graft

The aim of this study was to compare the effect of anesthesia with midazolam-fentanyl versus propofol-remifentanil on the BIS (bispectral index) in patients undergoing coronary artery bypass grafting (CABG). Sixty-four patients undergoing CABG were randomly assigned to one of two study groups: midazolam-fentanyl (MF, N= 32) or propofol-remifentanil (PR, N= 32). The BIS was measured before induction of anesthesia, five minutes after induction of anesthesia, at skin incision, sternotomy, pericardiotomy, aorta cannulation, onset of cardiopulmonary bypass, during rewarming, five minutes after separation from cardiopulmonary bypass, at thorax closure, and at the end of the surgery. There were no significant differences between the two groups with regard to age and gender. The difference in mean BIS between the two groups was significant (P < 0.05) at all times, except before induction, five minutes after induction, at skin incision and on rewarming. Changes in the BIS were lower in the PR group than in the MF group. Both techniques can provide adequate anesthesia in patients undergoing CABG. However, the probability of awareness during anesthesia is lower with propofol-remifentanil than with midazolam-fentanyl.

Fibre-optic intubation teaching in sedated patients with anticipated difficult intubation

BACKGROUND AND OBJECTIVES

The objective of the study was to assess the safety of training fibre-optic intubation performed under propofol light general anaesthesia in patients with an anticipated difficult intubation.

METHODS

Patients with ear, nose and throat cancer having at least two criteria for anticipated difficult intubation and scheduled for fibre-optic intubation were included prospectively. In 26 patients, intubation was performed by an anaesthesia resident (under senior supervision), whereas in 20 patients, it was performed by a senior anaesthesiologist. All patients received propofol light general anaesthesia adjusted to maintain both loss of consciousness and spontaneous ventilation.

RESULTS

Of the 46 patients, 45 had successful fibre-optic intubation, and one needed a rescue procedure because of hypoxaemia. Residents failed to intubate four patients, who were easily intubated by the senior. Episodic hypoxaemia (SPO2 < 90%) occurred in three patients in each group. No statistically significant difference was found between junior and senior neither on the duration of the procedure (9.3 +/- 4.9 vs. 7.5 +/- 4.0 min) nor on the propofol consumption (197 +/- 130 vs. 193 +/- 103 mg) or the ETCO2 at the end of the procedure (36 +/- 6 vs. 38 +/- 6 mmHg), respectively.

CONCLUSION

Teaching fibre-optic tracheal intubation in patients with anticipated difficult intubation and sedated with propofol did not increase morbidity significantly compared with an experienced anaesthesiologist. Fibre-optic intubation under propofol light general anaesthesia could be safely performed by a resident as long as a senior anaesthesiologist is permanently present, spontaneous ventilation is maintained and a rescue oxygenation technique is immediately available.

Target concentrations of remifentanil with propofol to blunt coughing during intubation, cuff inflation, and tracheal suctioning

BACKGROUND

The target blood concentrations of propofol and remifentanil, when used in combination, required to blunt the cough response to tracheal intubation, cuff inflation, and tracheal suctioning without neuromuscular blocking agents are not known.

METHODS

In a randomized prospective study, 81 patients were enrolled to determine which of three target remifentanil blood concentrations was required to blunt coughing during intubation, cuff inflation, and tracheal suctioning. Anaesthesia was achieved with propofol at a steady effect-site concentration of 3.5 microg ml(-1). The target blood remifentanil concentrations were 5, 10, or 15 ng ml(-1). These concentrations were maintained for 12 min before intubation.

RESULTS

There was no cough response to intubation in more than 74% of patients and no significant difference in the incidence of coughing with intubation between the three groups. Significant difference in coughing, diminishing with increasing remifentanil target concentration, was observed with cuff inflation (P=0.04) and tracheal suctioning (P=0.007). Bradycardia and hypotension was more frequent with the remifentanil target concentration of 15 ng ml(-1). Tracheal suctioning resulted in more coughing than intubation (P=0.01) or cuff inflation (P=0.004).

CONCLUSION

Target remifentanil blood concentrations of 5, 10, and 15 ng ml(-1) associated with a 3.5 microg ml(-1) propofol target blood concentration provided good intubating conditions and absence of cough about 75% of the time. Higher target remifentanil concentrations were associated with less coughing during tracheal tube cuff inflation and tracheal suctioning.

Sédation peropératoire à objectif de concentration avec le propofol : détermination des concentrations au site d'action et évaluation de l'index bispectral

OBJECTIVES

To determine the effect-site concentration (Ce) of propofol, required to achieving adequate sedation. To assess the efficacy and safety of a target-controlled infusion system during monitored anaesthesia care and to evaluate the ability of bispectral index (BIS) to predict sedation level. Study design. - Prospective clinical study.

PATIENTS

Women scheduled for insertion of tension-free vaginal tape under local anaesthetic infiltration.

METHODS

After premedication with hydroxyzine, 1% propofol was infused using the Diprifusor system at an initial target plasma concentration (Cc) of 1 microg/ml and then adjusted by steps of 0.2 microg/ml at 5 min intervals. The level of sedation was assessed using the observer's assessment of alertness/sedation (OAA/S) scale; the objective was to obtain an OAA/S level at 4 or 3 (response to verbal stimulation). Ce of propofol and BIS were noted every 5 min. Relation between Ce or BIS and OAA/S scale was analysed by linear regression and probability of prediction (P(K)).

RESULTS

Fifty patients aged 62 +/- 12 years were studied. Sedation at level 4 or 3 was observed in all patients. Ce of propofol and BIS to maintain this OAA/S score were, respectively, 1.0 +/- 0.2 microg/ml and 87 +/- 7. There was a linear relation between OAA/S scale and BIS or Ce; however, individual values demonstrate wide variability. The average of P(K) values computed for each patient for the BIS and Ce was 0.84 and 0.83, respectively.

CONCLUSIONS

Target-controlled infusion of propofol provides easy and safe management of intraoperative sedation, allowing a fast and precise adjustment of the propofol concentration to the clinical response of the patient.

Le propofol et l'AIVOC en neuro-anesthésie

Propofol is an intravenous anaesthetic agent, which presents interesting features for its use in neuro-anaesthesia: it is a powerful hypnotic that does not increase the intracranial pressure. The delay of recovery is short even after several hours of continuous infusion. This is essential for a fast neurologic examination. Continuous infusion should be preferred to bolus in order to prevent hypotension and decrease of the cerebral perfusion pressure. Target-controlled infusion models based on effect site concentrations are now available through several softwares. This technique appears especially useful for awake craniotomy and functional neurosurgery. The level of consciousness is easily fixed between deep anaesthesia and light sedation permitting to ask the patient to move following orders. A sedation controlled by the patient himself is even possible.

[Use of midazolam in postoperative sedation of patients with multiple organ failure treated with hemodiafiltration. Clinical study and pharmacokinetics]

OBJECTIVES

Evaluate the risk of accumulation of midazolam and conjugated 1-hydroxy-midazolam in high-risk ICU patients treated by continuous veno-venous haemofiltration.

STUDY DESIGN

A prospective pharmocokinetic and clinical evaluation in 11 patients, with hepatic and renal failure.

METHODS

Midazolam and metabolites were dosed in plasma and ultratiltration liquid by chromatography. Sedation was assessed by a simplified Ramsay score (EDS) with 4 levels.

RESULTS

The mean duration of continuous infusion was 11 +/- 6 days. Peak plasma levels were over 150 ng ml-1 during the first 3 days, but normalized after that, only by drug adjustment based on scoring and clinical observation. There was no progressive accumulation of OH-midazolam, in spite of high levels (> 1000 ng ml-1). The Sieving coefficient (S) was 0.11 +/- 0.10 and 0.44 +/- 0.15 for midazolam and conjugated OH-midazolam respectively. A significant clearance (9.6 +/- 1.9 ml min-1) was observed for the conjugated products. T 1/2 beta was 11 h and was correlated with the mean time of recovery. A significant correlation was found between sedation score and both midazolam (r = 0.47) and OH-midazolam (r = 0.32).

CONCLUSION

OH-midazolam risk of accumulation and significant clearance by haemodiafiltration should be taken into account in the drug adjustment in patients treated by continuous veno-venous haemofiltration.

[Sedation induced by midazolam in intensive care: pharmacologic and pharmacokinetic aspects]

OBJECTIVE

Review on midazolam in order to optimize drug utilisation and therapeutic monitoring.

DATA SOURCES

Research of English or French articles published until August 2001, using Medline database. The key words were: midazolam, pharmacokinetics, pharmacodynamic, sedation, drug interaction.

STUDY SELECTION

Original articles, clinical cases and letters to the Editor were selected. Animal studies were excluded.

DATA EXTRACTION

The articles were analysed according to their interest in midazolam clinical practice.

DATA SYNTHESIS

Midazolam is a benzodiazepine widely used in intensive care unit, as a sedative, anxiety-relieving, and amnesic drug. Midazolam could be used in patients with cardiac, or respiratory failure, and in neurosurgery. A great interindividual variability on pharmacokinetic and pharmacodynamic response was observed. In intensive care patients, elimination half-life is known to be widely increased. Midazolam is metabolised by hepatic microsomes. The major metabolite is the 1-hydroxymidazolam, which is pharmacologically active. A prolonged sedation due to an accumulation of conjugated metabolite was observed in renal failure patients. Enzymatic inductors or inhibitors could influence pharmacokinetics and pharmacodynamic effects of midazolam.

CONCLUSION

According to midazolam pharmacokinetic and pharmacodynamic variability, an individual dosage adjustment is essential for long-term sedation. Target controlled sedation could be a mean to limit the variability and to reach quickly the pharmacodynamic effect.

Effects of fentanyl, alfentanil, remifentanil and sufentanil on loss of consciousness and bispectral index during propofol induction of anaesthesia

The bispectral index (BIS) and a sedation score were used to determine and compare the effect of propofol in the presence of fentanyl, alfentanil, remifentanil and sufentanil. Seventy-five non-premedicated patients were assigned randomly into five groups (15 in each) to receive fentanyl, alfentanil, remifentanil, sufentanil or placebo. Opioids were administered using a target-con-trolled infusion device, to obtain the following predicted effect-site concentrations: fentanyl, 1.5 ng ml(-1); alfentanil, 100 ng ml(-1); remifentanil, 6 ng ml(-1); and sufentanil, 0.2 ng ml(-1). After this, a target-controlled infusion of propofol (Diprifusor) was started to increase concentration gradually, to achieve predicted effect-site concentrations of 1, 2, and 4 microg ml(-1). At baseline and at each successive target effect-site concentration of propofol, the BIS, sedation score and haemodynamic variables were recorded. At the moment of loss of consciousness (LOC), the BIS and the effect-site concentration of propofol were noted. The relationship between propofol effect-site concentration and BIS was preserved with or without opioids. In the presence of an opioid, LOC occurred at a lower effect-site concentration of propofol and at a higher BIS50 (i.e. the BIS value associated with 50% probability of LOC), compared with placebo. Although clinically the hypnotic effect of propofol is enhanced by analgesic concentrations of mu-agonist opioids, the BIS does not show this increased hypnotic effect.

[Target controlled infusion (TCI) anesthesia using propofol. Assessment of training and practice in the operating room]

OBJECTIVE

To evaluate overall awareness of TCI and the need for training in the TCI technique. To assess, among trained anaesthetists, the value of the session and the impact of TCI technique on their working practice.

STUDY DESIGN

Two prospective domestic surveys during the first quarter of 1999.

METHODS

Three hundred anaesthetists representative of French anaesthetists as a whole, and 336 anaesthetists who had taken part in a training course.

RESULTS

The notoriety of TCI was high and greater in the public sector compared with the private sector. Almost 3/4 of anaesthetists believed that training was necessary but only four anaesthetists out of ten TCI users said they had taken part in training sessions. After the training session nine anaesthetists out of ten became TCI users and would have recommended the training course despite the low number and variety of anaesthetic procedures observed during the practical part of training. The main difficulties reported during initial use were the choice of target concentrations and the management of drug interactions. Familiarisation to the technique was rapid (less than 20 procedures). Despite the lack of long experience (< 6 months for more than 2/3 of them), TCI appeared to be more likely used for anaesthesia of average duration.

CONCLUSIONS

TCI was perceived to be an innovative concept with a requirement of a specific training. This preliminary appraisal of training sessions was generally satisfactory but underline a need for future training sessions focused on practical aspects.

[Failure to recover after anesthesia attributed to a transient dissociative state]

Failure of a patient to recover rapidly after anaesthesia is a rare event, due to various causes, including medication related effects, metabolic disturbances or neurologic insults. We report a case in a middle aged physically healthy woman who failed to recover promptly after intravenous anaesthesia. Propofol was administered for 20 minutes. Results of neurologic assessment were normal, as were laboratory tests and CT-scan. Four hours after completion of the anaesthesia, return to consciousness occurred spontaneously. The patient had a history of depressive symptoms. However the psychiatric assessment was unremarkable. We hypothesise that she developed a transient dissociative disorder.