Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR) Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management. Part II

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factor, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

Spanish Society of Anesthesiology, Reanimation and Pain Therapy (SEDAR), Spanish Society of Emergency and Emergency Medicine (SEMES) and Spanish Society of Otolaryngology, Head and Neck Surgery (SEORL-CCC) Guideline for difficult airway management

The Airway Management section of the Spanish Society of Anesthesiology, Resuscitation, and Pain Therapy (SEDAR), the Spanish Society of Emergency Medicine (SEMES), and the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC) present the Guide for the comprehensive management of difficult airway in adult patients. Its principles are focused on the human factor, cognitive processes for decision-making in critical situations, and optimization in the progression of strategies application to preserve adequate alveolar oxygenation in order to enhance safety and the quality of care. The document provides evidence-based recommendations, theoretical-educational tools, and implementation tools, mainly cognitive aids, applicable to airway management in the fields of anesthesiology, critical care, emergencies, and prehospital medicine. For this purpose, an extensive literature search was conducted following PRISMA-R guidelines and was analyzed using the GRADE methodology. Recommendations were formulated according to the GRADE methodology. Recommendations for sections with low-quality evidence were based on expert opinion through consensus reached via a Delphi questionnaire.

Conventional stepwise vs. vital capacity rapid inhalation induction at two concentrations of sevoflurane

BACKGROUND AND OBJECTIVE

A multicentre study was conducted to compare three methods of inhalation induction with sevoflurane in adult premedicated patients.

METHODS

One-hundred-and-twenty-five adult patients of ASA I-II were scheduled for short elective surgical procedures (< 90 min) under general anaesthesia with spontaneous ventilation of the lungs via a laryngeal mask airway. Patients were randomly assigned to one of three groups: conventional stepwise inhalation induction group (Group C) or vital capacity rapid inhalation induction groups at 4.5% (Group VC4.5) or at 8% sevoflurane (Group VC8). Before anaesthetic induction, fentanyl 1 micro kg(-1) was given and the face mask applied with the anaesthetic breathing system primed with sevoflurane 4.5% or 8% in the respective vital capacity groups. Loss of eyelash reflex, time to cessation of finger tapping, laryngeal mask insertion, side-effects and adequacy of induction were recorded.

RESULTS

The time to loss of eyelash reflex was significantly shorter in both vital capacity groups vs. the control group: VC8: 68 +/- 7 s; and VC4.5: 94 +/- 6.5 s vs. C: 118 +/- 6.4s (P < 0.0001). Significant differences were found in all pairwise comparisons for time to cessation of tapping: Group VC8 (62 +/- 7 s), Group VC4.5 (85 +/- 6 s) and Group C (116 +/- 6 s; P < 0.0001). The time to laryngeal mask insertion was significantly shorter in the Group VC8 (176 +/- 13 s) compared with the other two groups, Group VC4.5 (219 +/- 13 s) and Group C (216 +/- 9 s). There were no significant differences in the incidence of side-effects between the three groups.

CONCLUSIONS

Inhalation induction of anaesthesia with sevoflurane with the three techniques tested is safe, reliable and well accepted by the patients. The vital capacity rapid inhalation group primed with sevoflurane 8% was the fastest method with no relevant side-effects.

[Decrease in isoflurane requirements and of postoperative pain with preanesthetic intrathecal morphine]

OBJECTIVES

1) To determine whether preanesthetic intrathecal administration of 0.5 mg morphine reduces isoflurane requirements for anesthetic maintenance. 2) To assess the duration of postoperative analgesia and the type and frequency of complications attributable to the procedure.

PATIENTS AND METHODS

A series of 45 adults were distributed into 3 groups of 15 patients each based on site of surgery and site of preanesthetic (30 min) injection of 0.5 mg pure morphine. Control group (C0) patients underwent lumbar surgery and received subcutaneous morphine. Group C0.5 patients also underwent lumbar surgery but received intrathecal morphine. Group A0.5 patients underwent long-duration high abdominal surgery and received intrathecal morphine. Anesthesia was maintained with nitrous oxide (60%) in oxygen (40%) and a variable concentration of isoflurane. Isoflurane needs were assessed by averaging six consecutive measurements of end-tidal isoflurane pressure (M30FETiso) taken at intervals of 5 min. Postoperative analgesia was evaluated by means of a visual analog scale that was converted to numerical units (VASn).

RESULTS

M30FETiso in group C0 (0.8%) was always higher (p < 0.01) than in the other two groups. M30FETiso in group A0.5 was higher (p < 0.01) than in group C0.5 during the first 150 min of surgery. After 180 min, there were no differences in M30FETiso (0.10-0.16%) between the two groups receiving intrathecal morphine. VASn results (mean +/- SD) in the first 4 hours were higher in group C0 (7.33 +/- 0.6) than in group C0.5 (1.13 +/- 0.35) and group A0.5 (1.07 +/- 0.26). The time of morphine-dependent analgesia was shorter (p < 0.01) in group C0 (0.62 +/- 0.38 hours) than in groups C0.5 (30.4 +/- 5.11 hours) and A0.5 (28 +/- 4.34 hours). There were no significant differences between the two groups receiving intrathecal morphine.

CONCLUSIONS

Preanesthetic subarachnoid lumbar injection of 0.5 mg of pure morphine reduced early requirements for isoflurane in lumbar surgery (0.14% after 60 min). This reduction was initially less in patients undergoing abdominal surgery (0.44% at 60 min) but was the same after 150 min. Postoperative analgesia was long-term and independent of type or duration of surgery. There was no respiratory depression after surgery and the incidence of postoperative complications was similar in the two groups that received subarachnoid morphine.

[Analysis of induction with 5% isoflurane and 60% nitrous oxide in premedicated adults]

OBJECTIVES

To analyze rapid inhalatory anesthetic induction in premedicated adults (fentanyl, droperidol, diazepam and atropine) with an inspired mixture of O2, N2O (60%) and 5% isoflurane as a means for accelerating induction time and reducing complications.

PATIENTS AND METHODS

We studied a series of 35 adult ASA-I patients at four times: baseline (1), premedication (2), induction (3) and postintubation (4). Measurements taken were arterial hemoglobin oxygen saturation (SpO2), arterial pressure (AP), heart rate (HR), end-tidal CO2 pressure (PETCO2) and respiratory frequency. We also recorded maximum end-tidal isoflurane pressure (FEtiso) at time 3; presence of apnea, cough and mask rejection at time 3; arrhythmia at times 3 and 4, and induction recall at time 3. Mean time of induction (time from start of induction to laryngoscopy) and the double product (HR x systolic AP) were calculated.

RESULTS

Coughing was observed in 20% (7/35) and was significantly associated with smoking; mask rejection was observed in 5.71% (2/35). The lowest SpO2 measurements occurred during period 2 and the highest during 3 (98.2 +/- 0.76). The incidence of apnea (77.14%, 27/35) was high during period 3, with mean PETCO2 values (+/- SD) of 40.71 +/- 4.19 mmHg and mean maximal FEtiso values of 1.6 +/- 0.53%. Mean time of induction was 96.28 +/- 5.19 s. There were no cases of recalled induction of arrhythmia in periods 3 and 4. The highest levels of AP and HR were recorded during period 4. The only difference in AP and HR between periods 2 and 3 was in diastolic AP, which was higher (p < 0.05) in period 3.

CONCLUSIONS

Rapid induction with 5% isoflurane is achieved within 1.5 min, with a 20% incidence of coughing and a 5% incidence of mask refusal. The high frequency of apnea (77%) is caused by the rapid elevation of alveolar isoflurane, which has an impact on the apneic threshold. Anesthetic induction with 5% isoflurane and 60% nitrous oxide in premedicated adults is accomplished with good maintenance of hemodynamic stability. However, tachycardia and arterial hypertension appear after laryngoscopy and tracheal intubation.