Glottic insertion of the ProSeal LMA occurs in 6% of cases: a review of 627 patients.

PURPOSE: Glottic insertion of the ProSeal Laryngeal Mask Airway (PLMA) has received little attention in the anesthesiology literature. We investigated the incidence and depth of insertion associated with this important cause for a failed insertion attempt with the PLMA. METHODS: With Institutional Review Board approval, we reviewed 15-months' use of the PLMA. Diagnosis of glottic insertion involved a test with children's bubble solution placed on the drain tube port, as well as a fibreoptic examination of the airway of patients experiencing airway obstruction. Patients were anesthetized and paralyzed and the PLMA was inserted deflated with the fingertip method (women size 4, men size 5). The cuff was inflated and a soap membrane established on the drain tube port. Glottic insertion was diagnosed by applying fingertip pressure to the patient's chest wall and observing pulmonary exhalation via the drain tube and bubble formation. The PLMA was then removed and reinserted without further assessment. For all patients, we used a fibrescope to determine the cause of unexplained airway obstruction after the PLMA was considered successfully inserted. RESULTS: There were 627 patients (391 women, 236 men). We diagnosed glottic insertion in 38/627 (6.1%) patients, 37 by the soap membrane test and one with airway obstruction and direct fibreoptic visualization of malposition. Following glottic insertion, successful reinsertion of the PLMA behind the larynx was always associated with greater depth of insertion by an average 2.0 cm. CONCLUSION: Glottic insertion can be easily and quickly diagnosed and our results suggest the incidence and importance of malposition are under-reported in the literature.

Paradoxical embolism in the left main coronary artery: diagnosis by transesophageal echocardiography.

We describe a patient with a paradoxical coronary embolism diagnosed by transesophageal echocardiography. The patient developed a stroke followed by a myocardial infarction. Coronary angiography showed an obstruction of the left main coronary artery. Transesophageal echocardiography showed the mechanism of the neurologic and cardiac events to be a paradoxical embolism. Emergency surgical retrieval of the thrombus lodged in the left main coronary ostium and of a separate thrombus traversing a patent foramen ovale was performed. To our knowledge, direct visualization of the paradoxical coronary embolism by echocardiography has not been reported previously. We discuss mechanisms responsible for paradoxical coronary embolism and review the literature pertaining to this condition.

Maximum minute ventilation test for the ProSeal laryngeal mask airway.

UNLABELLED: One of the distinguishing features of the ProSeal laryngeal mask airway (PLMA) is that it can cause upper airway obstruction, even when it is correctly inserted behind the cricoid cartilage. We used a hyperventilation test, the maximum minute ventilation test (MMV test), to aid in the diagnosis of upper airway obstruction after PLMA insertion. The patient was briefly hyperventilated for 15 s yielding a MMV value equal to 4 x (breaths/15 s) x (exhaled tidal volume). MMV values were collected in 317 adult women and men over 6 mo. Critical MMV values were obtained in 17 of 317 patients, 15 of 317 (4.7%) of which were due to insertion of the PLMA. The PLMA was removed in seven of 317 (2.2%) patients. The most common cause of upper airway obstruction due to the PLMA was laryngeal obstruction. This refers to compression of supraglottic and glottic structures with resulting narrowing and compromise of the airway. A second, much less common, form of airway obstruction was bilateral cuff infolding with or without downfolding of the epiglottis. Finally, we discuss the margin of safety for minute ventilation, defined as the excess of the MMV over and above basal minute ventilation requirements for the patient. With critical MMV, the margin of safety is drastically reduced or nonexistent. IMPLICATIONS: One of the distinguishing features of the ProSeal laryngeal mask airway (PLMA) is that it can cause upper airway obstruction, even when it is correctly inserted behind the cricoid cartilage. We used a hyperventilation test, the maximum minute ventilation test, to aid in the diagnosis of upper airway obstruction after PLMA insertion.

Gastric distention in a spontaneously ventilating patient with a ProSeal laryngeal mask airway.

IMPLICATIONS: Partial upper airway obstruction during spontaneous respiration with a ProSeal laryngeal mask airway can result in gastric distention.

Esophageal insufflation with normal fiberoptic positioning of the ProSeal laryngeal mask airway.

IMPLICATIONS: Esophageal insufflation can occur simultaneously with venting from the drain tube during positive pressure ventilation with the ProSeal laryngeal mask airway.