Pharyngeal function and airway protection during subhypnotic concentrations of propofol, isoflurane, and sevoflurane: volunteers examined by pharyngeal videoradiography and simultaneous manometry

Effect of ciprofol on swallowing function in patients undergoing painless gastrointestinal endoscopy

BACKGROUND

Gastroscopy is one of the most commonly used diagnostic modalities for upper gastrointestinal disorders. This study compared the effect of ciprofol and propofol on swallowing function during painless gastroenteroscopy.

METHODS

This was a single-center, placebo-controlled randomized trial. Three hundred sixty-eight patients undergoing painless gastroscopy were included in this study and randomly divided into 2 groups: the propofol group (PRO group, n = 183) and the ciprofol group (CIP group, n = 185). Sufentanil, ciprofol, and propofol are used to anesthetize the patients, and the effects of different solutions on these patients are compared and analyzed. The patient's general condition, vocal cord adduction reflex, dysphagia severity score, penetration and aspiration scale score, vital signs at different times, complications, recovery time (minutes), residence time in the resuscitation room (minutes), and adverse reactions were recorded.

RESULTS

During the examination, the incidence of severe swallowing dysfunction in CIP group was lower than that in PRO group (P < .05). The BP in CIP group was higher than that in PRO Group (P < .05). The HR of CIP group was lower than that of PRO Group (P < .05). SpO2 in CIP group was higher than that in PRO Group (P < .05). The recovery time of CIP group was longer than that of PRO Group, and the postanesthesia care unit stay time of PRO group was longer than that of CIP group(P < .05). The incidence of respiratory depression, hypotension and cough in CIP group was lower than that in PRO Group (P < .05). The incidence of injection pain in CIP group was lower than that in PRO Group (P < .05).

CONCLUSION

Compared with propofol, ciprofol has less inhibition on swallowing function, less impact on hemodynamics, less respiratory depression, and less injection pain, which is more suitable for painless gastroscopy.

Comparison of the effects of intravenous propofol and propofol with low-dose ketamine on preventing postextubation cough and laryngospasm among patients awakening from general anaesthesia: A prospective randomised clinical trial

BACKGROUND

Coughing and laryngospasm are undesirable consequences occurring when patients awaken from general anaesthesia. The objective of the study aimed to compare the effects of intravenous propofol and propofol with low-dose ketamine on preventing postextubation cough and laryngospasm.

METHODS

In all, 120 patients scheduled surgery under general anaesthesia were randomly assigned into three groups. Patients in the control group (C-group) received intravenous 0.9% NaCl, while patients in the propofol group (P-group) received intravenous 0.25mg/kg propofol and patients in the propofol combined with ketamine group (PK-group) received intravenous 0.25mg/kg of propofol plus 0.15mg/kg of ketamine. Drugs were administered before extubation. Incidence and severity of coughing and laryngospasm were recorded by a blinded anaesthesiologist.

RESULTS

Subjects of the PK-group (25%) experienced significantly reduced incidence of postoperative cough than that in the P-group (55%) and C-group (72.5%) (all P < 0.05). The severity of cough in the PK-group was significantly less than that in the P-group and C-group (P = 0.039 and P < 0.001, respectively). No significant difference was found in the incidence and severity of laryngospasm between comparison groups.

CONCLUSION

Intravenous combination of propofol and low-dose ketamine significantly reduced the incidence and severity among patients awakening from general anaesthesia.

General anesthetic techniques for enhanced recovery after surgery: Current controversies

General anesthesia technique can influence not only immediate postoperative outcomes, but also long-term outcomes beyond hospital stay (e.g., readmission after discharge from hospital). There is lack of evidence regarding superiority of total intravenous anesthesia over inhalation anesthesia with regards to postoperative outcomes even in high-risk population including cancer patients. Optimal balanced general anesthetic technique for enhance recovery after elective surgery in adults includes avoidance of routine use preoperative midazolam, avoidance of deep anesthesia, use of opioid-sparing approach, and minimization of neuromuscular blocking agents and appropriate reversal of residual paralysis. Given that the residual effects of drugs used during anesthesia can increase postoperative morbidity and delay recovery, it is prudent to use a minimal number of drug combinations, and the drugs used are shorter-acting and administered at the lowest possible dose. It is imperative that the discerning anesthesiologist consider whether each drug used is really necessary for accomplishing perioperative goals.

A Simple Risk Scoring System for Predicting the Occurrence of Aspiration Pneumonia After Gastric Endoscopic Submucosal Dissection

BACKGROUND

Aspiration pneumonia after endoscopic submucosal dissection (ESD) is rare, but can be fatal. We aimed to investigate risk factors and develop a simple risk scoring system for aspiration pneumonia.

METHODS

We retrospectively reviewed medical records of 7833 patients who underwent gastric ESD for gastric neoplasm under anesthesiologist-directed sedation. Candidate risk factors were screened and assessed for significance using a least absolute shrinkage and selection operator (LASSO)-based method. Top significant factors were incorporated into a multivariable logistic regression model, whose prediction performance was compared with those of other machine learning models. The final risk scoring system was created based on the estimated odds ratios of the logistic regression model.

RESULTS

The incidence of aspiration pneumonia was 1.5%. The logistic regression model showed comparable performance to the best predictive model, extreme gradient boost (area under receiver operating characteristic curve [AUROC], 0.731 vs 0.740). The estimated odds ratios were subsequently used for the development of the clinical scoring system. The final scoring system exhibited an AUROC of 0.730 in the test dataset with risk factors: age (≥70 years, 4 points), male sex (8 points), body mass index (≥27 kg/m2, 4 points), procedure time (≥80 minutes, 5 points), lesion in the lower third of the stomach (5 points), tumor size (≥10 mm, 3 points), recovery time (≥35 minutes, 4 points), and desaturation during ESD (9 points). For patients with total scores ranging between 0 and 33 points, aspiration pneumonia probabilities spanned between 0.1% and 17.9%. External validation using an additional cohort of 827 patients yielded AUROCs of 0.698 for the logistic regression model and 0.680 for the scoring system.

CONCLUSIONS

Our simple risk scoring system has 8 predictors incorporating patient-, procedure-, and sedation-related factors. This system may help clinicians to stratify patients at risk of aspiration pneumonia after ESD.

Sugammadex Versus Neostigmine for Reversal of Rocuronium Neuromuscular Block in Patients Having Catheter-Based Neurointerventional Procedures: A Randomized Trial

BACKGROUND

Catheter-based endovascular neurointerventions require deep neuromuscular blocks during the procedure and rapid subsequent recovery of strength to facilitate neurological evaluation. We tested the primary hypothesis that sugammadex reverses deep neuromuscular blocks faster than neostigmine reverses moderate neuromuscular blocks.

METHODS

Patients having catheter-based cerebral neurointerventional procedures were randomized to: (1) deep rocuronium neuromuscular block with posttetanic count 1 to 2 and 4-mg/kg sugammadex as the reversal agent or (2) moderate rocuronium neuromuscular block with train-of-four (TOF) count 1 during the procedure and neuromuscular reversal with 0.07-mg/kg neostigmine to a maximum of 5 mg. Recovery of diaphragmatic function was assessed by ultrasound at baseline before the procedure and 90 minutes thereafter. The primary outcome-time to reach a TOF ratio ≥0.9 after administration of the designated reversal agent-was analyzed with a log-rank test. Secondary outcomes included time to successful tracheal extubation and the difference between postoperative and preoperative diaphragmatic contraction speed and distance.

RESULTS

Thirty-five patients were randomized to sugammadex and 33 to neostigmine. Baseline characteristics and surgical factors were well balanced. The median time to reach TOF ratio ≥0.9 was 3 minutes (95% confidence interval [CI], 2-3 minutes) in patients given sugammadex versus 8 minutes (95% CI, 6-10 minutes) in patients given neostigmine. Sugammadex was significantly faster by a median of 5 minutes (95% CI, 3-6 minutes; P < .001). However, times to tracheal extubation and diaphragmatic function at 90 minutes did not differ significantly.

CONCLUSIONS

Sugammadex reversed deep rocuronium neuromuscular blocks considerably faster than neostigmine reversed moderate neuromuscular blocks. However, times to extubation did not differ significantly, apparently because extubation was largely determined by the time required for awaking from general anesthesia and because clinicians were willing to extubate before full neuromuscular recovery. Sugammadex may nonetheless be preferable to procedures that require a deep neuromuscular block and rapid recovery.

Refractory Severe Laryngospam During Rapid Sequence Induction: A Case Report

Laryngospasm is a rare cause of upper-airway obstruction in adults. It most commonly occurs during light anesthesia. We report a case of severe laryngospasm following rapid sequence induction in an adult requiring an emergency neurosurgical procedure. Laryngospasm occurred despite deep anesthesia with ketamine and neuromuscular blockade with succinylcholine. Several intubation attempts failed. Therefore, 2 hypotheses are considered: succinylcholine resistance and ketamine-induced laryngospasm. To our knowledge, this is the first description of laryngospasm occurring despite deep anesthesia and neuromuscular blockade. An idiosyncratic effect of ketamine may be involved, although this phenomenon has not yet been studied.

Comparison of remifentanil concentrations with and without dexmedetomidine for the prevention of emergence cough after nasal surgery: a randomized double-blinded trial

Background

Preventing emergence cough after nasal surgery is critical. Emergence cough can provoke immediate postoperative bleeding, which leads to upper airway obstruction. In the present study, we compared the effect-site concentration (Ce) of remifentanil to prevent emergence cough after propofol anesthesia for nasal surgery when remifentanil was or was not combined with dexmedetomidine.

Methods

Forty-seven patients with propofol-remifentanil anesthesia for nasal surgery were randomly assigned to a dexmedetomidine group (Group D, n = 23) or a saline group (Group S, n = 24). Group D and Group S were infused with dexmedetomidine (0.5 μg/kg) and saline, respectively, for 10 min before the completion of surgery. A predetermined Ce of remifentanil was infused until extubation. Remifentanil Ce to prevent cough in 50 and 95% of patients (EC₅₀ and EC₉₅) was estimated using modified Dixon’s up-and-down method and isotonic regression. Hemodynamic and recovery parameters were recorded.

Results

The EC₅₀ of remifentanil Ce was significantly lower in Group D than in Group S (2.15 ± 0.40 ng/mL vs. 2.66 ± 0.36 ng/mL, p = 0.023). The EC₉₅ (95% CI) of remifentanil Ce was also significantly lower in Group D [2.75 (2.67–2.78) ng/mL] than in Group S [3.16 (3.06–3.18) ng/mL]. Emergence and recovery variables did not differ between the two groups.

Conclusion

The remifentanil EC₅₀ to prevent cough after propofol-remifentanil anesthesia was significantly lower (approximately 19%) when a combination of remifentanil and 0.5 μg/kg dexmedetomidine was used than when remifentanil infusion alone was used in patients undergoing nasal surgery. Therefore, the Ce of remifentanil may be adjusted to prevent emergence cough when used in combination with dexmedetomidine.

Trial registration

ClinicalTrials.gov (NCT03622502, August 9, 2018).

Swallowing ability and intra-oral water-retaining ability during moderate propofol sedation in healthy human volunteers: A prospective observational study

BACKGROUND

The cough reflex or aspiration under monitored anaesthesia care might be associated with sedative-induced changes in swallowing and intra-oral water-retaining abilities.

OBJECTIVES

To investigate the effects of moderate propofol sedation on swallowing and intra-oral water-retaining ability.

DESIGN

Prospective observational study.

SETTING

Single tertiary care centre during 2017.

PARTICIPANTS

A total of 13 healthy adult volunteers.

INTERVENTION

Volunteers in the supine position were asked to retain 10 ml of orally injected water for 5 min. After 5 minutes or when the water was spontaneously swallowed, the retention time and residual intra-oral water volume were measured. Subjects then voluntarily swallowed a further 10 ml of injected water and the residual water volume was measured. This whole process was repeated under sedation with propofol at effect-site concentrations of 0.5, 1.0 and 1.5 μg ml-1.

MAIN OUTCOME MEASURES

The primary outcome was the estimated volume swallowed (swallowing volume); the secondary outcome was water retention time.

RESULTS

Median water retention time decreased from 300 to 11 s (P < 0.001), and greater spontaneous swallowing was induced with increased propofol effect-site concentrations measuring up to 1.5 μg ml-1 (P < 0.001). The median of the estimated swallowing volumes with voluntary swallowing while awake and with all three concentrations of propofol were 9.5, 9.6, 9.6 and 9.4 ml, respectively (P = 0.805); more water remained after spontaneous swallowing than after voluntary swallowing at all concentrations. Differences in mean estimated swallowing volumes between voluntary and spontaneous swallowing were 3.4 ml (95% CI, 0.9 to 6.0, P = 0.016) for 0.5 μg ml-1, 4.1 ml (95% CI, 1.8 to 6.3, P = 0.002) for 1.0 μg ml-1 and 5.1 ml (95% CI, 3.4 to 6.8, P < 0.001) for 1.5 μg ml-1.

CONCLUSIONS

Moderate propofol sedation decreases water-retaining ability but has no effect on voluntary swallowing. Ensuring that patients can respond under sedation may effectively prevent the unexpected cough reflex and aspiration by enabling occasional voluntary swallowing.

TRIAL REGISTRATION

UMIN Clinical Trials Registry identifier: UMIN000027517.

Titration of sevoflurane anesthesia to optimize the time to regain airway reflexes in patients undergoing elective surgery: A randomized clinical trial comparing desflurane and sevoflurane anesthesia

BACKGROUND

Desflurane has adverse environmental effects, but has clinical advantages to speed emergence and return of protective airway reflexes compared with sevoflurane. We hypothesized that weaning of the inspired sevoflurane during the final 15 minutes of surgery would eliminate differences in airway reflex recovery between these agents.

METHODS

After obtaining IRB approval and informed consent, 40 patients undergoing elective surgery (≥1-hour) randomly received desflurane or sevoflurane. Patients swallowed 20 mL of water without drooling or coughing, and then received sedation and PONV pre-medication. Anesthesia was induced using propofol and fentanyl and maintained with desflurane or sevoflurane through a laryngeal mask airway maintaining a bispectral index of 45-50 and 50-60 during the final 15 minutes before surgery end. Cardiorespiratory variables and age-adjusted minimal alveolar concentration were recorded. The duration between anesthetic discontinuation and first appropriate response to command was measured; the laryngeal mask airway was removed. Two minutes after responding to command, patients were positioned semi-upright and attempted to swallow water. If successful swallowing was not achieved, the test was repeated every 4 minutes after each failure until successful swallowing was achieved.

RESULTS

Average anesthetic concentration and bispectral index was similar in patients receiving desflurane vs sevoflurane. Response times after discontinuation of anesthetics were similar. There were no differences in the recovery of swallowing ability between desflurane and sevoflurane groups.

CONCLUSION

Weaning of sevoflurane during the final 15 minutes of surgery eliminates clinical advantages of the more rapid return of airway reflexes with desflurane.

Management of Refractory Laryngospasm

Laryngospasm has been well described in patients emerging from general anesthesia (GA) and is routinely managed with intermittent positive-pressure mask ventilation, a temporary increase in the depth of anesthesia, or small, titrated amounts of succinylcholine. Patients with severe laryngospasm require reintubation to maintain adequate oxygenation and ventilation. However, reintubation may be only a temporary solution because laryngospasm may recur during re-emergence and re-extubation; thus, anesthesiologists need a comprehensive plan that addresses potential causes of laryngospasm and incorporates continuous positive airway pressure (CPAP) for patients with difficulty emerging from GA. Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) is a noninvasive ventilation and oxygenation technique used to provide apneic oxygenation, which also generates CPAP. THRIVE uses a high-flow nasal cannula and is more easily tolerated than CPAP with a tight-fitting mask. To our knowledge, we present the first case of refractory laryngospasm during emergence from GA that was successfully managed with THRIVE.

Mandibular advancement impairs swallowing ability more than head extension but less than mouth opening in the supine position

Mandibular advancement in the supine position may influence swallowing during dental treatment under intravenous sedation. This study investigated the influence of mandibular advancement in the supine position on swallowing ability, compared with head extension and mouth opening. The water swallowing test was performed in 13 healthy, awake, supine, adult subjects under four head and mandibular positions. An electromyogram of the suprahyoid muscles was recorded; the duration and peak amplitude were examined. A greater volume of water remained in the mouth during mouth opening and mandibular advancement relative to the neutral position; the volume in the mandibular advancement position was larger and smaller than that in the head extension position and during mouth opening, respectively. The duration of the electromyogram in the head extension position was longer than that in the mandibular advancement position, without differences in the amplitude. Thus, swallowing ability in the supine position was more impaired with mandibular advancement, relative to neutral and head extension positions, but less than that observed with mouth opening. Although unconfirmed by electromyogram, our findings suggest that head extension might improve airway patency by reducing the impairment of swallowing ability compared with mandibular advancement.

Comparison of upper airway patency in patients with mild obstructive sleep apnea during dexmedetomidine or propofol sedation: a prospective, randomized, controlled trial

Background

In addition to propofol, dexmedetomidine is a suitable alternative for intraoperative sedation in procedures requiring regional anesthesia. To date, however, little is known about the influences of each drug on upper airway patency. Accordingly, the authors investigated differences between dexmedetomidine and propofol sedation in the occurrence of upper airway obstruction and requirements for airway intervention in patients with mild obstructive sleep apnea.

Methods

Patients with an apnea/hypopnea index of 5–14/h according to Watch-PAT 200 analysis were enrolled in this study. Spinal anesthesia was routinely performed for surgery. Intraoperative sedation was initiated using either dexmedetomidine or propofol infusion at a level of modified observer’s assessment of alertness/sedation scale 3. The primary outcome was the proportion of patients exhibiting signs of upper airway obstruction. A sign of upper airway obstruction was defined as no detection of end-tidal carbon dioxide for at least 10 s despite respiratory efforts.

Results

A total of 50 patients were included in the final analysis (dexmedetomidine [n = 26]; propofol [n = 24]). During the intraoperative sedation period, there was a significantly lower proportion of patients exhibiting signs of upper airway obstruction in the dexmedetomidine group than in the propofol group (11.5% vs. 41.7%, P = 0.035). An artificial airway was inserted in 1 patients (3.8%) and 5 patient (20.8%) in the dexmedetomidine and propofol groups, respectively (P = 0.093).

Conclusion

Dexmedetomidine sedation was associated with a lower incidence of upper airway obstruction than propofol sedation in patients with mild obstructive sleep apnea.

Trial registration number

Clinical trials.gov (NCT02993718): Retrospectively registered.

The Effect of Anesthetic Choice (Sevoflurane Versus Desflurane) and Neuromuscular Management on Speed of Airway Reflex Recovery

BACKGROUND

Nonintubated patients receiving sevoflurane have slower protective airway reflex recovery after anesthesia compared with patients receiving desflurane. We asked whether this difference would remain significant among intubated patients receiving rocuronium or whether the impact of variable neuromuscular recovery would predominate and thus minimize differences between anesthetics.

METHODS

After obtaining written informed consent, patients were randomly assigned to receive sevoflurane (n = 41) or desflurane (n = 40), with neuromuscular monitoring by quantitative train-of-four (TOF) method using accelerometry. Intubation was facilitated by administration of 1 mg/kg rocuronium. Neuromuscular block was produced, with the goal of maintaining 10% to 15% of baseline function. After surgery, neostigmine 70 µg/kg + glycopyrrolate 14 µg/kg was administered. When TOF ratio reached ≥ 0.7, anesthetic was discontinued and fresh gas flow was raised to 15 L/m. The time of first response to command was noted, after which patients were given a 20-mL water swallowing test at 2, 6, 14, 22, 30, and 60 minutes. The following average time intervals were compared between the 2 intervention groups: anesthetic discontinuation to first response to command (T1); first response to command to first successful passing of swallow test (T2); and anesthetic discontinuation to first successful passing of swallow test (T3). We also compared the rates of successful swallow tests at 2 minutes after first response to command in the 2 groups, first categorizing as failures all those who were unable to take the test at 2 minutes, and then excluding 10 patients unable to take the test at this time for reasons other than somnolence (n = 10).

RESULTS

Patients receiving desflurane passed the swallowing test at shorter time intervals after first response to command than did patients receiving sevoflurane (Wilcoxon-Mann-Whitney odds = 1.60; 95% confidence interval [CI], 1.01-2.69; P = 0.054). Two minutes after the first response to command, among all 81 patients, the chance of passing the swallowing test was higher after desflurane compared with sevoflurane anesthesia (relative risk = 1.6; 95% CI, 1.0-2.5; P = 0.04). Of the 71 patients (as above), we observed a significantly higher chance of passing at 2 minutes after first response to command (relative risk = 1.8; 95% CI, 1.2-2.7; P = 0.006) in patients receiving desflurane (25/33) compared with those receiving sevoflurane (16/38). In 18 of 81 and 16 of 71 patients, the neuromuscular monitoring and reversal protocols were not followed (neostigmine underdosed, extubation at TOF <0.7, or reliance on tactile as opposed to quantitative TOF measurement). In both the total cohort and the subset of 71, neuromuscular protocol adherence increased the chance of passing the swallow test, independent of anesthetic assignment in multivariable logistic regression (P = 0.02 and P = 0.006, respectively), demonstrating significant effect on airway reflex recovery independent of chosen anesthetic.

CONCLUSIONS

Compared with sevoflurane, desflurane allowed faster recovery of airway reflexes after anesthesia in intubated patients. Clinical management of neuromuscular block, including full reversal and the use of quantitative TOF, affects airway reflex recovery-an effect that may be at least as profound as the choice of potent inhaled anesthetic.

Removal of Laryngeal Mask Airway in Adults Under Target-Controlled, Propofol-Fentanyl Infusion Anesthesia: Awake or Deep Anesthesia?

After emergence from anesthesia, the incidence and severity of adverse airway effects caused by the laryngeal mask airway (LMA) can vary, depending on when the device was removed; nonetheless, reports differ regarding the exact optimal timing of LMA removal. The purpose of this study was to compare the rate of adverse events between 2 groups: those whose LMA was removed under general anesthesia ("deep" group) or under target-controlled infusion (TCI) of propofol ("awake" group).Institutional Review Board approval and written informed consent were obtained; 124 patients were then randomly allocated into either the "awake" group or the "deep" group. Anesthesia was induced and maintained using TCI of propofol, as well as intravenous fentanyl. In the "deep" group, the LMA was removed after surgery while the patients were deeply anesthetized using a target effect-site propofol concentration of 2 μg/mL, whereas in the "awake" group, the device was removed while the patients followed verbal instructions. The incidence of the following adverse events was recorded: coughing, straining, bronchospasm, laryngospasm, clenching, breath holding, gross purposeful movement, airway obstruction, retching, vomiting, and oxygen desaturation. If any such event occurred, the LMA removal was considered a failure. Airway hyperreactivity was recorded and graded - based on the severity of cough, breath holding, and oxygen desaturation.The failure rate was higher in the "awake" group (15/61; 24.6%) than in the "deep" group (5/60; 8.3%). Airway hyperreactivity was mild (score, <3) in both groups.Removal of the LMA under deep anesthesia using a target-controlled, effect-site propofol concentration of 2 μg/mL may be safer and more successful than removal when patients are fully awake after surgery.

The effects of propofol, ketamine and combination of them in prevention of coughing and laryngospasm in patients awakening from general anesthesia: A randomized, placebo-controlled, double blind clinical trial

BACKGROUND

Coughing and laryngospasm are undesirable outcomes occurring during emergence from general anesthesia. We compared the effect of small doses of propofol, ketamine and a combination of them on the occurrence and severity of coughing and laryngospasm in patients awakening from general anesthesia.

MATERIALS AND METHODS

160 patients who were scheduled to undergo operations under general anesthesia were randomly assigned to one of the following groups, 40 in each group: propofol group (0.25 mg/kg intravenous (IV) propofol), ketamine group (0.25 mg/kg IV ketamine), combination group (0.25 mg/kg IV propofol, and 0.25 mg/kg IV ketamine) and control (0.1 ml/kg IV saline). Drugs were administered before extubation at previously defined time. Presence and severity of coughing and laryngospasm were recorded within twominutes after extubation.

RESULTS

The presence of coughing in the combination group (27.5%) was less than that in other groups; also it was less frequent in the propofol group (57.5%) than the control (82.5%) (all P < 0.05). But the incidence did not differ between the propofol and the ketamine (70%) group; nor did it differ between the ketamine and control groups (P = 0.356 and P = 0.121, respectively). The cases with severe coughing (grade 3) in the combination group (none) were significantly less than in the propofol (four) and the control groups (seven) (P = 0.040 and P = 0.006 respectively). There was no significant difference between the groups in frequency of laryngospasm.

CONCLUSION

Administration of propofol or combination of propofol and ketamine decreases the incidence of post extubation coughing. This combination can also decrease severe cases.

Effects of morphine and midazolam on pharyngeal function, airway protection, and coordination of breathing and swallowing in healthy adults

BACKGROUND

Drugs used for sedation in anesthesia and intensive care may cause pharyngeal dysfunction and increased risk for aspiration. In this study, the authors investigate the impact of sedative doses of morphine and midazolam on pharyngeal function during swallowing and coordination of breathing and swallowing.

METHODS

Pharyngeal function, coordination of breathing and swallowing, and level of sedation were assessed by manometry, videoradiography, measurements of respiratory airflow, and a visual analog scale in 32 healthy volunteers (age 19 to 35 yr). After baseline recordings, morphine (0.1 mg/kg) or midazolam (0.05 mg/kg) was administered intravenously for 20 min, followed by recordings at 10 and 30 min after the end of infusion.

RESULTS

Pharyngeal dysfunction, seen as misdirected or incomplete swallowing or penetration of bolus to the airway, increased after morphine infusion to 42 and 44% of swallows compared with 17% in baseline recordings. Midazolam markedly increased incidence of pharyngeal dysfunction from 16 to 48% and 59%. Morphine prolonged apnea before swallowing, and midazolam increased the number of swallows followed by inspiration.

CONCLUSION

Morphine and midazolam in dosages that produce sedation are associated with increased incidence of pharyngeal dysfunction and discoordinated breathing and swallowing, a combination impairing airway protection and potentially increasing the risk for pulmonary aspirations.

Anesthesia and increased hypercarbic drive impair the coordination between breathing and swallowing

BACKGROUND

Coordination between breathing and swallowing helps prevent aspiration of foreign material into the respiratory tract. The authors examined the effects of anesthesia and hypercapnia on swallowing-breathing coordination.

METHODS

In a randomized controlled crossover study, general anesthesia with propofol or sevoflurane was titrated using an up-down method to identify the threshold for suppression of the motor response to electrical stimulation of the forearm. Additional measurements included bispectral index, genioglossus electromyogram, ventilation (pneumotachometer), and hypopharyngeal pressure. During wakefulness and at each level of anesthesia, carbon dioxide was added to increase the end-tidal pressure by 4 and 8 mmHg. A swallow was defined as increased genioglossus activity with deglutition apnea and an increase in hypopharyngeal pressure. Spontaneous swallows were categorized as physiological (during expiration or followed by expiration) or pathological (during inspiration or followed by an inspiration).

RESULTS

A total of 224 swallows were analyzed. Anesthesia increased the proportion of pathological swallows (25.9% vs. 4.9%) and decreased the number of swallows per hour (1.7±3.3 vs. 28.0±22.3) compared to wakefulness. During anesthesia, hypercapnia decreased hypopharyngeal pressure during inspiration (-14.1±3.7 vs. -8.7±2 mmHg) and increased minute ventilation, the proportion of pathological swallows (19.1% vs. 12.3%), and the number of swallows per hour (5.5±17.0. vs. 1.3±5.5).

CONCLUSIONS

Anesthesia impaired the coordination between swallowing and respiration. Mild hypercapnia increased the frequency of swallowing during anesthesia and the likelihood of pathological swallowing. During anesthesia, the risk for aspiration may be further increased when ventilatory drive is stimulated.

Addition of sub-anaesthetic dose of ketamine reduces gag reflex during propofol based sedation for upper gastrointestinal endoscopy: A prospective randomised double-blind study

Background and Aims:

Gag reflex is unwanted during upper gastrointestinal endoscopy (UGIE). Experimental studies have demonstrated that N-methyl-D-aspartate receptor antagonism prevents gag reflex. We conducted a study to determine if sub-anaesthetic doses of ketamine, added to propofol, reduce the incidence of gag reflex.

Methods:

This prospective, randomised, double-blind and placebo-controlled study was done in a tertiary care hospital. A total of 270 patients undergoing UGIE, were randomised to propofol (P) group (n = 135) or propofol plus ketamine (PK) group (n = 135). All patients received propofol boluses titrated to Ramsay sedation score of not <4. Patients in PK group in addition received ketamine, 0.15 mg/kg immediately before the first-propofol dose. Top-up doses of propofol were given as required. Stata 11 software (StataCorp.) was used to calculate the proportion of patients with gag reflex and the corresponding relative risk. Propofol consumed and time to recovery in the two groups was compared using Student's t-test and Cox proportional hazards regression respectively.

Results:

Significantly, fewer patients in the PK group had gag reflex compared to the P group (3 vs. 23, risk ratio = 0.214, 95% confidence interval [CI], 0.07-0.62; P = 0.005). The incidence of hypotension (6 vs. 16, risk ratio = 0.519, 95% CI = 0.25-1.038; P = 0.06), number of required airway manoeuvres (4 vs. 19, risk ratio = 0.32, 95% CI = 0.13-0.74; P = 0.014), median time to recovery (4 min vs. 5 min, hazard ratio = 1.311, 95% CI = 1.029-1.671; P = 0.028) and propofol dose administered (152 mg vs. 167 mg, 95% CI = 4.74-24.55; P = 0.004) was also less in the PK group compared to the P group.

Conclusion:

Ketamine in sub-anaesthetic dose decreases gag reflex during UGIE.

Aspiration Induced by Remifentanil

Background:

Remifentanil is widely used for monitored anesthesia care in spontaneously breathing patients. However, the authors’ previous studies have shown that remifentanil induces subjective swallowing difficulties, which may increase the risk of aspiration.

Methods:

Twenty-five healthy volunteers participated in a double-blind, randomized, crossover trial at the University Hospital in Örebro, Örebro, Sweden. The volunteers were studied on two different occasions during which they received either remifentanil with an effect-site target concentration of 3 ng/ml or saline over 1 h. A radionuclide tracer was infused simultaneously into the nasopharynx at a rate of 0.1 ml/min. Aspiration was determined by lung scans, and subjective swallowing difficulties and grip strength were evaluated. The primary outcome was the difference in occurrence of aspiration between remifentanil and placebo treatments. The secondary outcomes were differences in swallowing difficulty and grip strength and the association between aspiration and swallowing difficulty.

Results:

During remifentanil and placebo infusion, 48 and 12% of the volunteers aspirated, respectively, difference: 36% (95% CI, 10 to 62%). A similar significant difference was found for swallowing difficulties but not for the association between aspiration and swallowing. No difference was found in grip strength between the two treatments.

Conclusions:

Remifentanil infusion at concentrations used in monitored anesthesia care increases the incidence of aspiration. However, the subjective swallowing difficulty induced by remifentanil is not indicative of the aspiration risk.

Both head extension and mouth opening impair the ability to swallow in the supine position

Head position and mouth opening in the supine position may impair the ability to swallow. If this does occur, it would lead to retention of intra-oral fluids during dental treatment, which would lead to stimulation of the cough reflex. This study was conducted to investigate how head position and mouth opening affect swallowing ability. The water swallowing test was performed in 13 healthy adult subjects in the supine position. The subjects were asked to swallow 10 mL of water that was injected into the mouth in a single attempt. After swallowing, the residual intra-oral water was suctioned and its volume was measured. An electromyogram (EMG) of the suprahyoid (SH) muscles was also recorded during the test. The duration of SH muscle activity and peak amplitude of SH EMG were examined. The water swallowing test was performed under three head positions (neutral, extended and flexed) and four mouth opening patterns (interincisal distances of 0, 20, 30 and 40 mm). The wider the subject opened the mouth, the more the water remained in the mouth after swallowing. The residual volume of water was more in the extended position compared with that in the neutral and flexed positions. Peak amplitude of SH EMG decreased with mouth opening. Duration of SH muscle activity was longer in the extended position than in the neutral and flexed positions. Head extension and mouth opening can induce difficulty in swallowing in the supine position by extending the duration of SH muscle activity while reducing its intensity.

Pharyngeal function and breathing pattern during partial neuromuscular block in the elderly: effects on airway protection

BACKGROUND

Intact pharyngeal function and coordination of breathing and swallowing are essential for airway protection and to avoid respiratory complications. Postoperative pulmonary complications caused by residual effects of neuromuscular-blocking agents occur more frequently in the elderly. Moreover, elderly have altered pharyngeal function which is associated with increased risk of aspiration. The purpose of this study was to evaluate effects of partial neuromuscular block on pharyngeal function, coordination of breathing and swallowing, and airway protection in individuals older than 65 yr.

METHODS

Pharyngeal function and coordination of breathing and swallowing were assessed by manometry and videoradiography in 17 volunteers, mean age 73.5 yr. After control recordings, rocuronium was administered to obtain steady-state train-of-four ratios of 0.70 and 0.80 followed by spontaneous recovery to greater than 0.90.

RESULTS

Pharyngeal dysfunction increased significantly at train-of-four ratios 0.70 and 0.80 to 67 and 71%, respectively, compared with 37% at control recordings, and swallowing showed a more severe degree of dysfunction during partial neuromuscular block. After recovery to train-of-four ratio of greater than 0.90, pharyngeal dysfunction was not significantly different from the control state. Resting pressure in the upper esophageal sphincter was lower at all levels of partial neuromuscular block compared with control recordings. The authors were unable to demonstrate impaired coordination of breathing and swallowing.

CONCLUSION

Partial neuromuscular block in healthy elderly individuals causes an increased incidence of pharyngeal dysfunction from 37 to 71%, with impaired ability to protect the airway; however, the authors were unable to detect an effect of partial neuromuscular block on coordination of breathing and swallowing.

Effects of anesthetics, sedatives, and opioids on ventilatory control

This article provides a comprehensive, up to date summary of the effects of volatile, gaseous, and intravenous anesthetics and opioid agonists on ventilatory control. Emphasis is placed on data from human studies. Further mechanistic insights are provided by in vivo and in vitro data from other mammalian species. The focus is on the effects of clinically relevant agonist concentrations and studies using pharmacological, that is, supraclinical agonist concentrations are de-emphasized or excluded.

Violating traditional NPO guidelines with PO contrast before sedation for computed tomography

BACKGROUND

Administration of PO contrast within 2 hours before sedation for abdominal computed tomography (CT) is controversial because it violates American Society of Anesthesiologists guidelines that recommend 2 hours of fasting for clear fluids before sedation.

OBJECTIVE

This study aimed to review the administration of PO contrast for patients undergoing propofol sedation for abdominal CT and to evaluate the impact of violation of traditional 2-hour NPO guidelines on care.

METHODS

Sedation records were reviewed from January 2010 to October 2011 from all patients who received PO contrast within 2 hours of propofol sedation for abdominal CT. A control group of patients receiving intravenous contrast only before propofol sedation and abdominal CT was reviewed. Demographics, time between PO contrast administration and sedation, and amount of PO contrast were recorded. Outcome measures including success of sedation and adverse events (vomiting, suctioning, use of O₂ or advanced airway, unplanned admissions) were recorded.

RESULTS

Eighty-five patients received PO contrast within 2 hours before sedation for abdominal CT; 21 controls were identified. No differences in demographics or outcome measures were seen. No significant differences were seen in rates of interventions or adverse outcomes between groups. Median time between the successive PO contrast doses and propofol administration was 1.6 hours and 0.6 hours.

CONCLUSIONS

Administering oral contrast material within 2 hours of propofol sedation for abdominal CT in children seems to be relatively safe compared with those sedated after traditional NPO time frames.

Monitoring during difficult airway management

Monitoring is crucial to assure safety during difficult airway management. Several reports have indicated that the most of the adverse outcomes associated with difficult airway management could have been avoided with the use of necessary monitors, such as a pulse oximeter and a capnometer. Nevertheless, airway complications continue to be major problems during anesthesia, in particular, in patients with difficult airways. In this brief review, I stress the role of monitoring in detecting inadvertent esophageal intubation, during sedation for awake tracheal intubation, during general anesthesia, and during emergence from anesthesia, in patients with difficult airways.

Postoperative Respiratory Muscle Dysfunction

Postoperative pulmonary complications are responsible for significant increases in hospital cost as well as patient morbidity and mortality; respiratory muscle dysfunction represents a contributing factor. Upper airway dilator muscles functionally resist the upper airway collapsing forces created by the respiratory pump muscles. Standard perioperative medications (anesthetics, sedatives, opioids, and neuromuscular blocking agents), interventions (patient positioning, mechanical ventilation, and surgical trauma), and diseases (lung hyperinflation, obesity, and obstructive sleep apnea) have differential effects on the respiratory muscle subgroups. These effects on the upper airway dilators and respiratory pump muscles impair their coordination and function and can result in respiratory failure. Perioperative management strategies can help decrease the incidence of postoperative respiratory muscle dysfunction. Such strategies include minimally invasive procedures rather than open surgery, early and optimal mobilizing of respiratory muscles while on mechanical ventilation, judicious use of respiratory depressant anesthetics and neuromuscular blocking agents, and noninvasive ventilation when possible.

Comparison of the antitussive effect of remifentanil during recovery from propofol and sevoflurane anaesthesia

This prospective randomised study compared the antitussive effect of remifentanil during recovery from either propofol or sevoflurane anaesthesia. Seventy-four female patients undergoing thyroidectomy were anaesthetised with either propofol and remifentanil or sevoflurane and remifentanil. During recovery, remifentanil was maintained at an effect-site concentration of 2 ng.ml(-1) until extubation and the occurrence of coughing, haemodynamic parameters and recovery profiles were compared between the two groups. During recovery, neither the incidence nor the severity of cough (incidence 20% with propofol; 24% with sevoflurane, p = 0.77), nor the haemodynamic parameters were different between the two groups. Time to awakening and time to extubation were significantly shorter in the propofol group (4.7 min, 6.1 min min, respectively) compared with the sevoflurane group (7.9 min and 8.9 min respectively) (p < 0.001 and p = 0.002, respectively). An effect-site concentration of 2 ng.ml(-1) of remifentanil was associated with smooth emergence from both propofol and sevoflurane anaesthesia.

Effect of a small dose of propofol or ketamine to prevent coughing and laryngospasm in children awakening from general anesthesia

BACKGROUND

Coughing during emergence from general anesthesia may be detrimental in children. We compared the effect of a small dose of propofol or ketamine administered at the end of sevoflurane anesthesia on the incidence or severity of coughing in children undergoing a minimal invasive operation.

METHODS

One hundred and eighteen children aged between 3 and 15 years, American Society of Anesthesiologists (ASA) status I, were enrolled in this randomized double blind study. Anesthesia was induced with propofol or ketamine and maintained with sevoflurane in N(2)O/O(2). Each group received propofol 0.25 mg/kg or ketamine 0.25 mg/kg and the control group received saline 0.1 ml/kg. The decision to perform tracheal extubation was based on specified criteria, including the resumption of spontaneous respiration. During emergence from anesthesia and extubation, coughing was observed and graded at predefined times.

RESULTS

The incidence of emergence without coughing was higher in the propofol group than in the ketamine and control group (19%, 11% and 6%, respectively), whereas the incidence of severe coughing was higher in the control group than in propofol and ketamine group (17.14%, 10.0% and 6.98%, respectively).

CONCLUSIONS

The addition of propofol 0.25 mg/kg decreased the incidence of coughing after sevoflurane general anesthesia in children undergoing non-painful procedures.

Breathing and swallowing in normal man--effects of changes in body position, bolus types, and respiratory drive

BACKGROUND

Coordination of breathing and swallowing is essential for airway protection and dyscoordination may cause morbidity and mortality.

METHODS

Using a recently developed technique for high accuracy respiratory measurements of airflow during swallowing, we investigated the effects of body position (upright vs left lateral), bolus type (spontaneously swallowed saliva vs water), and respiratory drive (normo- vs hypercapnia) on coordination of breathing and swallowing in 32 healthy volunteers.

KEY RESULTS

Swallows were in all cases (100%) proceded by expiration and 98% were also followed by expiration, regardless of body position, bolus type, or respiratory drive. While the endpoint of postswallow apnea correlated well to the endpoint of pharyngeal swallowing, duration of preswallow apnea was highly variable. In a small fraction of swallows followed by inspiration (3%), the expiratory phase before swallowing and duration of postswallow apnea was significantly longer. Body position and respiratory drive affected the increase in upper esophageal sphincter tone during inspiration. Increased respiratory drive also reduced swallowing frequency and shortened duration of preswallow apnea. Water swallows had longer duration of preswallow apnea.

CONCLUSIONS & INFERENCES

Swallowing occurs during the expiratory phase of respiration, and the fraction of swallows preceded and followed by expiration approach 100% in healthy humans. This integration between breathing and swallowing remains unchanged regardless of body position, bolus characteristics, or respiratory drive. Our results provide a platform for future studies aiming at understanding how this integration is changed by aging, diseases, and drugs.

The duration of residual neuromuscular block after administration of neostigmine or sugammadex at two visible twitches during train-of-four monitoring

BACKGROUND

Adequate recovery from neuromuscular block (NMB) is imperative for the patient to have full control of pharyngeal and respiratory muscles. The train-of-4 (TOF) ratio should return to at least 0.90 to exclude potentially clinically significant postoperative residual block. Fade cannot be detected reliably with a peripheral nerve stimulator (PNS) at a TOF ratio >0.4. The time gap between loss of visual fade by using a PNS until objective TOF ratio has returned to >0.90 can be considered "the potentially unsafe period of recovery." According to our hypothesis the duration of this period would be significantly shorter with sugammadex than with neostigmine.

METHODS

Fifty patients received volatile anesthetics, opioids, and a rocuronium-induced NMB. TOF-Watch without a preload was used, but the anesthesiologist relied on visual evaluation of the TOF responses only. At end of operation, patients were randomized to receive either neostigmine 50 μg/kg or sugammadex 2 mg/kg, when 2 twitch responses were detected after the last dose of rocuronium. Timing of tracheal extubation was based on PNS and clinical data. Duration of the potentially unsafe period of recovery after reversal by either neostigmine or sugammadex was analyzed. Mann-Whitney U test and Pearson χ(2) test were used for statistical analysis.

RESULTS

The times [mean ± sd (range)] from loss of visual fade to TOF ratio >0.90 were 10.3 ± 5.5 (1.3 to 26.0) minutes and 0.3 ± 0.3 (0.0 to 1.0) minutes in the neostigmine and sugammadex groups, respectively (P < 0.001). The times from reversal by neostigmine or sugammadex to TOF ratio >0.90 were 13.3 ± 5.7 (3.5 to 28.9) and 1.7 ± 0.7 (0.7 to 3.5) minutes, respectively (P < 0.001). The values of TOF ratios at the time of loss of visual fade were 0.34 ± 0.14 (0.00 to 0.56) in patients given neostigmine and 0.86 ± 0.11 (0.64 to 1.04) in patients given sugammadex (P < 0.001).

CONCLUSIONS

There is a significant time gap between visual loss of fade and return of TOF ratio >0.90 after reversal of a rocuronium block by neostigmine. Sugammadex in comparison with neostigmine allows a safer reversal of a moderate NMB when relying on visual evaluation of the TOF response.

Vocal cord function and bispectral index in pediatric bronchoscopy patients emerging from propofol anesthesia

OBJECTIVE

In children undergoing bronchoscopy for evaluation of stridor or respiratory symptoms, movement of the vocal cords is routinely assessed at the conclusion of flexible bronchoscopy with children still anesthetized. The effect of anesthesia on vocal cord function is not well described. This study aimed to characterize the relationship between depth of propofol anesthesia, as measured by Bispectral Index (BIS), and vocal cord movement in pediatric patients.

METHODS

Children between 6 months and 12 years of age presenting for diagnostic flexible bronchoscopy were enrolled in this prospective observational study. Anesthesia was maintained with a propofol infusion which was discontinued upon completion of the lower airway evaluation. An independent observer recorded the BIS score every 15 sec from discontinuation of propofol whereas the pulmonologist continued to observe vocal cord motion. BIS scores were also recorded for each observed clinical endpoint (paradoxical and normal vocal cord movement, complete vocal cord closure, and volitional movement).

RESULTS

Data were analyzed for 47 subjects. The BIS values increased significantly from the conclusion of the lower airway evaluation with return of normal vocal cord movement, complete vocal cord closure, and volitional movement (P < 0.0005). BIS readings were higher for patients younger than 2 years. Paradoxical vocal cord movement was documented in 10.6% of subjects, but resolved in all subjects.

CONCLUSIONS

Our findings suggest that return of vocal cord function during emergence from propofol anesthesia is related to decreasing anesthetic depth with complete vocal cord closure occurring at BIS values near those associated with volitional movement.

Analgesia and sedation for painful interventions in children and adolescents

BACKGROUND

Painful procedures on children and adolescents often have to be performed with the aid of analgesia and sedation in order to prevent pain and emotional distress. Moreover, many procedures can be performed more rapidly and more effectively in a relaxed patient. Because the combination of analgesia and sedation can cause serious or even life-threatening complications, it must be accompanied by the same safety precautions as a general anesthetic.

METHODS

Selective review of the literature.

RESULTS

A high level of safety can be achieved by adherence to the published guidelines of the societies for anesthesiology and pediatrics. The depth of sedation during procedures performed under combined analgesia and sedation is often equivalent to that resulting from general anesthesia. Therefore, in order to avoid serious complications, combined analgesia and sedation should only be administered by physicians trained in pediatric anesthesia or pediatric critical care. This is particularly so when propofol is used, because it has a narrow therapeutic range and can cause cardiorespiratory respiratory problems without warning. As long as the appropriate safety precautions are followed, non-anesthesiologists can also administer propofol in combination with an analgesic, such as ketamine, to children and adolescents.

CONCLUSION

In children and adolescents, the combination of analgesia and sedation can prevent the emotional trauma that would result from a painful procedure, while often enhancing the quality of the procedure itself. This method should be considered a variant of general anesthesia. Accordingly, any non-anesthesiologist employing this method must be as well versed as an anesthesiologist in the management of its specific side effects and complications.

Monitored anesthesia care (MAC) sedation: clinical utility of fospropofol

Fospropofol, a phosphorylated prodrug version of the popular induction agent propofol, is hydrolyzed in vivo to release active propofol, formaldehyde, and phosphate. Pharmacodynamic studies show fospropofol provides clinically useful sedation and EEG/bispectral index suppression while causing significantly less respiratory depression than propofol. Pain at the injection site, a common complaint with propofol, was not reported with fospropofol; the major patient complaint was transitory perianal itching during the drug's administration. Although many clinicians believe fospropofol can safely be given by a registered nurse, the FDA mandated that fospropofol, like propofol, must be used only in the presence of a trained anesthesia provider.

Effect of increased body mass index and anaesthetic duration on recovery of protective airway reflexes after sevoflurane vs desflurane

BACKGROUND

Increased BMI may increase the body's capacity to store potent inhaled anaesthetics, more so with more soluble agents. Accordingly, we asked whether increased BMI and longer anaesthesia prolonged airway reflex recovery.

METHODS

We measured time from anaesthetic discontinuation until first response to command (T1); from response to command until ability to swallow (T2); and from anaesthetic discontinuation to recovery of ability to swallow (T3) in 120 patients within three BMI ranges (18-24, 25-29, and >or=30 kg m(-2)). All received sevoflurane or desflurane, delivered via an LMA.

RESULTS

T1 and T3 after sevoflurane exceeded T1 and T3 after desflurane: 6.6 (sd 4.2) vs 4.0 (1.9) min (P<0.001), and 14.1 (sd 8.3) vs 6.1 (2.0) min (P<0.0001). T3 correlated more strongly with BMI after sevoflurane (28 s per kg m(-2), P=0.02) than desflurane (7 s per kg m(-2), P=0.03). Regarding T2, patients receiving sevoflurane with BMI >or=30 kg m(-2) were less often able to swallow 2 min after response to command than were those with BMI 18-24 or 25-29 kg m(-2) (3/20 vs 10/20 or 9/20, P<0.05). Each sevoflurane MAC-hour delayed T3 by 4.5 min (268 s) (R=0.46, P<0.001) whereas each desflurane MAC-hour delayed T3 by 0.2 min (16 s) (R=0.10, P=0.44).

CONCLUSIONS

Prolonged sevoflurane administration and greater BMI delay airway reflex recovery. The contribution of BMI to this delay is more pronounced after sevoflurane than desflurane.

[Residual curarization and pharyngeal muscles: remain vigilant!]

The different concepts treating of "residual curarization" were presented according to two directions: the analysis of their contents--epidemiologic, clinical, instrumental--and the description of the pharyngeal striated muscles functions in these contexts. It appears that certain, too marked, "residual curarization" levels remain a well-evidenced factor increasing some morbidities in numerous clinical situations. All the methods of instrumental monitoring of the level of curarization--mecanography, electromyography, accelerometry--appeared useful to document the levels of "residual curarization" before patient's extubation or awakening. Today, for our speciality, it became particularly clear that: neither the selected muscle-- adductor pollicis--, neither the test currently privileged--train-of-four 2Hz--, nor the thresholds currently selected--0.90 or 1.00--did not constitute the unavoidable proof of a "residual curarization" complete absence. For the healthy volunteer receiving a curare, a train of four of the adductor pollicis greater than 0.90 can exist in presence of spirometric alterations evidencing the lack of adequate pharyngeal dilatation. In daily routine, the pharyngeal control is already disturbed by numerous molecules including: benzodiazepines, halogenated vapours, propofol, i.e. even under non-hypnotic concentrations. Faced to such evidences, our medical speciality will, undoubtedly, have to acquire new knowledge to develop muscle relaxant management control processes eliminating the surmorbidities related to "residual curarization". These tests must be validated also to exclude morbidity-prone dysfunctions of the pharyngeal striated muscles. Considering this new paradigm would be a major safety evolution for our speciality.