Semi-sitting Versus Supine Position in Endoscopic Skull Base Surgery (PosESS)

  • End date
    Aug 20, 2023
  • participants needed
  • sponsor
    University Hospital, Basel, Switzerland
Updated on 20 April 2022


This study is to prospectively compare the standard supine (control group) and the semi-sitting position (head elevation of 30°; intervention group) in endoscopic endonasal pituitary surgery.


The endonasal endoscopic approach (EEA) for pituitary surgery is standardly performed with the patient in supine position (SP). The semi-sitting position (SSP) is routinely used for the traditional microscopic transsphenoidal approach and also for posterior fossa surgery. The SSP results in lower intracranial pressure when compared to the supine position due to decreased venous congestion. As a result, intraoperative bleeding may be reduced, potentially leading to decreased surgical morbidity and improved surgical workflow. Studies during endoscopic sinus surgery have shown a significant reduction of blood loss when the patient is placed in a reverse Trendelenburg position with a head elevation of 30°. This study is to prospectively compare the standard supine (control group) and the semi-sitting position (head elevation of 30°; intervention group) in endoscopic endonasal pituitary surgery.

Condition Pituitary Adenoma
Treatment Endonasal endoscopic pituitary surgery in semi-sitting position, Endonasal endoscopic pituitary surgery in supine position
Clinical Study IdentifierNCT04584866
SponsorUniversity Hospital, Basel, Switzerland
Last Modified on20 April 2022


Yes No Not Sure

Inclusion Criteria

Patients with a presumed pituitary pathologies who are suitable for endoscopic endonasal surgical resection

Exclusion Criteria

Patients with known hemorrhagic or thrombophilic disorders
Patients with conditions associated with high central venous pressure: congestive heart failure, pulmonary hypertension, chronic obstructive pulmonary disease (COPD), interstitial lung disease, pregnancy
Patients with poor cardiopulmonary condition (unable to perform 4 metabolic equivalents without stopping (climb a flight of stairs))
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