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Sevoflurane and Laryngeal Reflex Responses in Pediatric Patients

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ClinicalTrials.gov Identifier: NCT00665418
Recruitment Status : Terminated (Recruitment finished earlier, because all 40 patients enrolled)
First Posted : April 23, 2008
Last Update Posted : March 12, 2009
Information provided by:
University Hospital, Basel, Switzerland

Brief Summary:
To describe laryngeal and respiratory reflex responses after controlled laryngeal stimulation in pediatric patients anesthetized with sevoflurane and to compare the evoked responses at two levels of anesthesia. To determine whether laryngeal and respiratory reflex responses after controlled laryngeal stimulation are completely suppressed in subjects when anesthetized with a MACEI95 (EI = endotracheal intubation) sevoflurane Hypothesis: The incidence of apnea with laryngospasm evoked by laryngeal stimulation will be reduced by 20% (from 25% to 5%) when the end-tidal concentration of sevoflurane is increased from 2.5% (MAC50) to 4.7% (MACEI95)

Condition or disease Intervention/treatment Phase
Laryngospasm Drug: sevoflurane Phase 4

Detailed Description:

Induction of anesthesia inhaling sevoflurane is a very common practice in pediatric anesthesia.However, unwarranted exaggerated upper airway defensive reflexes that develop into apnea and laryngospasm with resultant hypoxemia is more common and also more severe.

Despite their obvious clinical significance, reflexes that involve the function of the upper airway are only minimally understood and information on such reflexes is scarce in anesthetized humans. Nonetheless, a model was developed by analyzing respiratory variables and endoscopic images after stimulating the laryngeal mucosa with a small amount of distilled water. Clinical experience suggests that laryngeal reflexes occur more frequently under light levels of anesthesia. However, in contrast to other inhalational agents such as halothan, available data for sevoflurane suggest that an inverse correlation of laryngeal responsiveness to depth of hypnosis or end-tidal concentrations of sevoflurane (in adults and children) is less obvious. However, in all previous studies assessing laryngeal reflex responses under sevoflurane only low concentrations of sevoflurane (range of 1.0 - 2.5 Vol%) were examined. This is an important limitation because in clinical practice higher concentrations of sevoflurane are used, especially during manipulation of the airway, while the risk of airway irritation is high. Thus, the proposed study aims to explore the question whether the occurrence of laryngospasm can be reliably suppressed when high concentrations of sevoflurane are used.

Based on results of experiments assessing conditions that facilitate tracheal intubation, it is clear, that increasing the end-tidal concentration of volatile agents obtunds airway reflexes. Regarding intubation conditions, the concept of MACEI 50% or 95% describes the minimum alveolar concentration (MAC) of a volatile anesthetic needed by 50 or 95% of the patients, respectively, to prevent all movement during and immediately after tracheal intubation. The proposed study aims to assess respiratory reflex responses at these levels of anesthesia by analyzing the respiratory variables and endoscopic images. The incidences of well-defined airway reflexes (cough reflex, spasmodic panting, expiration reflex, and apnea with laryngospasm, central apnea) will be examined. Apnea with laryngospasm will be of primary interest in our study and digital video analysis of the glottic opening will allow for a detailed analysis of laryngeal performance.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 40 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Prevention
Official Title: Impact of High Concentrations of Sevoflurane on Laryngeal Reflex Responses in Pediatric Patients
Study Start Date : February 2008
Actual Primary Completion Date : August 2008
Actual Study Completion Date : August 2008

Resource links provided by the National Library of Medicine

Drug Information available for: Sevoflurane

Arm Intervention/treatment
Experimental: 1 Drug: sevoflurane
sevoflurane 2.5% versus 4.7% (inhaled concentration) 10min each
Other Name: Ultane

Primary Outcome Measures :
  1. Occurence of laryngospasm (defined as complete closure of the vocal or false cords with apnea lasting >10sec) after laryngeal stimulation [ Time Frame: 5min ]

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Ages Eligible for Study:   25 Months to 84 Months   (Child)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • ASA I + II
  • Elective intervention under general anesthesia

Exclusion Criteria:

  • Reactive airway disease
  • Respiratory tract infection (previous 2 weeks)
  • Malignant hyperthermia
  • Neuromuscular disease
  • Cardiac disease

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00665418

Sponsors and Collaborators
University Hospital, Basel, Switzerland
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Principal Investigator: Thomas O Erb, MD Universitiy children's hospital Basel
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Responsible Party: Albert Urwyler MD, Department of Anesthesia
ClinicalTrials.gov Identifier: NCT00665418    
Other Study ID Numbers: UNIBAS_UKBB_ANE_LR4
First Posted: April 23, 2008    Key Record Dates
Last Update Posted: March 12, 2009
Last Verified: March 2009
Keywords provided by University Hospital, Basel, Switzerland:
Additional relevant MeSH terms:
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Vocal Cord Dysfunction
Laryngeal Diseases
Respiratory Tract Diseases
Respiration Disorders
Otorhinolaryngologic Diseases
Platelet Aggregation Inhibitors
Anesthetics, Inhalation
Anesthetics, General
Central Nervous System Depressants
Physiological Effects of Drugs