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Muscle Relaxants and Post-Anesthesia Complications (PORC)

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified September 2008 by Technische Universität München.
Recruitment status was:  Recruiting
Information provided by:
Technische Universität München Identifier:
First received: September 15, 2008
Last updated: NA
Last verified: September 2008
History: No changes posted
This Germany-wide, multi-center, epidemiologic study is designed to evaluate the incidence of post-operative/anesthesia effects of muscle relaxants (i.e. post-operative residual curarization: PORC) and their effect on patient outcome. Aside from biometric data, type of operation, use of muscle relaxants and neuromuscular monitoring, all patients will be clinically evaluated after their operation in the post-anesthesia care unit. To look at long-term effects, patients will be followed-up 28 days after their operation/anesthesia regarding post-operative/anesthesia morbidity and mortality.

Condition Intervention
Postoperative Residual Curarization
Other: None (anesthesia)

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Epidemiologic Study on Short and Long-Term Effects of Anesthesia With Muscle Relaxants (Epidemiologische Untersuchung Kurz- Und längerfristiger Auswirkungen Der Anästhesie Mit Muskelrelaxanzien)

Resource links provided by NLM:

Further study details as provided by Technische Universität München:

Primary Outcome Measures:
  • Survival [ Time Frame: 28 days after anesthesia ]

Estimated Enrollment: 20000
Study Start Date: September 2008
Estimated Study Completion Date: March 2009
Groups/Cohorts Assigned Interventions
Other: None (anesthesia)

Detailed Description:

Muscle relaxants are integral part of modern anesthesia. They optimize intubating conditions, reduce laryngeal trauma and improve operating conditions. Drawback is a possible pharmacological (muscle relaxing) effect of these drugs beyond the end of the operation (i.e. post-operative residual curarization: PORC). PORC is a relevant complication after general anesthesia. Reportedly about 30% of all patients who received muscle relaxants show signs of PORC when arriving in the post-anesthesia care unit. PORC comprises the risk of impaired post-operative fine motor and coordinative skills with a possible impairment of swallowing pharyngeal secretions with an increased risk of aspiration after extubation. Possible deleterious effects of this could be pneumonia, bronchitis, myocardial infarction, cardiac insufficiency, stoke or re-operation. In a pilot study we were able to identify clinical assessment criteria to assess patients' risk for aspiration, which are now part of the post-anesthesia evaluation of every patient.

Unfortunately there is a major pitfall arising from the inability to clearly identify PORC. Although objective neuromuscular monitoring is the golden standard to measure neuromuscular transmission during anesthesia, clinical signs have been used to identify muscle weakness postoperatively. One reason for this practice is the varying action of muscle relaxants at different muscle groups demonstrating neuromuscular monitoring to be insufficiently sensitive to detect PORC symptoms at the pharyngeal muscles. This situation may lead to a seldom use of neuromuscular monitoring devices and may add to a decreasing use of muscle relaxants in clinical anesthesia.

In this Germany-wide, multi-center, epidemiologic study we would like to evaluate if the use of muscle relaxants, or signs of their prolonged effect beyond the end of the operation/anesthesia (PORC), affect the further in-hospital stay and post-operative morbidity and mortality. The sampling in 8 German hospitals should determine the number of patients with clinically relevant signs of muscle weakness at the time of arrival in the post-anesthesia care unit. Therefore a data entry form has been developed by the principal and sub-investigators of the 8 participating study hospitals. This data entry form enables the staff in charge of the post-anesthesia care unit to acquire and to document residual neuromuscular blockades. The sampling will be done in the 8 participating hospitals on 21 randomized working days over a period of 24 hours. To identify the potential risk factors for postoperative residual curarization, the known predictors for neuromuscular rest blockades are recorded as well. Known predictors are for example: type and amount of muscle relaxant, duration of operation and anesthesia, surgical procedure, patients' age, anesthesia-technique, antagonization of muscle relaxant or neuromuscular monitoring. Further, the patients' progress in the post-anesthesia care unit is documented.

The 28 day outcome of patients is followed up with a second data entry form which includes health-economical aspects. Reported are complications, duration of intensive care unit and hospital stay, as well as remaining health damages at the time of discharge. To estimate the significance of PORC, data of patients with PORC is compared to data of patients without PORC. These patients are recruited during the first data collection period in the post-anesthesia care unit. The control for any patient with PORC is the next one arriving in the post-anesthesia care unit without PORC.


Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
All patients receiving anesthesia

Inclusion Criteria:

  • All patients attended by an anesthesiologist

Exclusion Criteria:

  Contacts and Locations
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Please refer to this study by its identifier: NCT00753389

Contact: Manfred Prof.Dr. Blobner, MD 0894140 ext 7206
Contact: Heidrun Dr. Fink, MD 0894140 ext 6289

Klinik für Anaesthesiologie, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22 Recruiting
München, Bavaria, Germany, 81675
Contact: Manfred Prof. Dr. Blobner, MD    +49894140 ext 7206   
Contact: Heidrun Dr. Fink, MD    +49894140 ext 6289   
Principal Investigator: Manfred Prof. Blobner, MD         
Sub-Investigator: Götz Prof. Geldner, MD         
Sub-Investigator: Gabriele Prof. Nölge- Schomburg, MD         
Sub-Investigator: Thomas Prof. Standl, MD         
Sub-Investigator: Hugo Prof. van Aken, MD         
Sub-Investigator: Friedrich Prof. Pühringer, MD         
Sub-Investigator: Jens Prof. Scholz, MD         
Sub-Investigator: Alexander PD. Dr. Schleppers, MD         
Sponsors and Collaborators
Technische Universität München
Principal Investigator: Manfred Prof.Dr. Blobner, MD Klinik für Anaesthesiologie, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 München
  More Information

Responsible Party: Prof. Dr. Manfred Blobner, Klinik für Anaesthesiologie, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Str. 22, 81675 München Identifier: NCT00753389     History of Changes
Other Study ID Numbers: PORC_main
Study First Received: September 15, 2008
Last Updated: September 15, 2008

Keywords provided by Technische Universität München:
Postoperative residual curarization,
muscle relaxants,
morbidity mortality

Additional relevant MeSH terms:
Muscle Hypotonia
Delayed Emergence from Anesthesia
Neuromuscular Manifestations
Neurologic Manifestations
Nervous System Diseases
Signs and Symptoms
Postoperative Complications
Pathologic Processes
Central Nervous System Depressants
Physiological Effects of Drugs processed this record on April 21, 2017