CASMED FORE-SIGHT Identifies Reductions in Cerebral Oxygenation in Beach Chair Shoulder Arthroscopy Patients
– Study Also Observed Link between Cerebral Desaturation Events and
Branford, Conn. – June 22, 2010 – CAS Medical Systems, Inc. (NASDAQ: CASM) today announced that a new study published on-line in Anesthesia & Analgesia demonstrating the benefits associated with monitoring absolute cerebral oximetry using the FORE-SIGHT® Absolute Oximeter on patients undergoing arthroscopic shoulder surgery1.
The beach chair position has been used for shoulder arthroscopic procedures since the early 1980s and has gained popularity because it offers a number of technical advantages over the lateral decubitus approach2,3. In the United States, approximately two-thirds of arthroscopic and open shoulder procedures are performed in the beach chair position and, although rare, catastrophic neurologic events such as brain and spinal cord injury, visual loss, and cerebrovascular events have been reported following surgery in this position4,5,6,7. The Anesthesia Patient Safety Foundation (APSF) Newsletter (Winter 2009-2010) stated, "There have been increasing reports of severe neurological injury in previously healthy patients having surgery in head-above-heart positions (shoulder surgery in the beach chair position) but the incidence and mechanisms are unknown."8
In a recent (Oct 2009) APSF workshop focused on the topic of cerebral perfusion pressure in the beach chair position, Dr. Robert K. Stoelting, President of the APSF, introduced the APSF's position statement regarding this issue: "The APSF believes that reports of global ischemic brain damage following surgical procedures in the semi-sitting beach chair position may reflect unrecognized cerebral hypoperfusion." 9 He also stated, "Patient safety may benefit from a discussion of acceptable cerebral perfusion pressures and methods to monitor the adequacy of cerebral blood flows."9
In response to the workshop, the APSF is funding the creation of the Neurologic Injury after Non-Supine Surgery Registry (NINS) to "collect and analyze adverse neurologic outcomes following shoulder arthroscopy surgery"8 and is also offering research funding to further study problems associated with "unexpected neurocognitive deficits in patients undergoing general anesthesia during surgery in non-supine positions."8
In this new independent study to be published in Anesthesia & Analgesia by researchers at the Department of Anesthesiology, NorthShore University HealthSystem, University of Chicago Pritzker School of Medicine, data was collected on 124 patients undergoing elective shoulder arthroscopy in two approximately equal sized groups. One group had surgery performed in the beach chair position (BCP), the second group had surgery performed in the lateral decubitus position (LDP).
The results from the study showed that cerebral desaturation events occurred frequently in patients in the BCP, whereas there were no desaturation events observed in a similar group of patients undergoing surgery in the LDP. The study included an intervention protocol for clinicians when a cerebral desaturation event as measured by the FORE-SIGHT monitor occurred, thereby allowing clinicians to proactively treat the patients and reduce the duration of the event. The study also reported a strong correlation between cerebral desaturation events and a multi-fold increase in the incidence of post-operative nausea and vomiting.
Lead author, Dr. Glenn S. Murphy, MD, stated, "We routinely use FORE-SIGHT in our cardiac surgery cases. The near-infrared spectroscopy technology provides non-invasive, simple to use, continuous monitoring of regional cerebral tissue oxygen saturation (SctO2) and allows for immediate recognition and treatment of cerebral desaturation events that would otherwise be undetected with conventional intraoperative monitoring. Although orthopedic patients in the beach chair position are at risk for cerebral hypoperfusion, no previous clinical trials have assessed changes in SctO2 in this patient population. Results from this study demonstrate that significant reductions in SctO2 occur in patients in the beach chair position despite the use of a protocol designed to maintain a systemic mean arterial pressure within 20% of pre-surgical supine position pressure."
1 Murphy GS, Szokol JW, Marymont JH, Greenberg SB, Avram MJ, Vender JS, Vaughn J, Nisman M. Cerebral oxygen desaturation events assessed by Near-Infrared Spectroscopy during shoulder arthroscopy in the beach chair and lateral decubitus positions, Anesth Analg 2010 May 27. [Epub ahead of print] Abstract available at: http://www.anesthesia-analgesia.org/content/early/2010/05/27/ANE.0b013e3181e33bd9.abstract.
2 Gelber PE, Reina F, Caceres E, Monllau JC. A comparison of risk between the lateral decubitus and the beach-chair position when establishing an anteroinferior shoulder portal: a cadaveric study. Arthroscopy 2007;23:5228
3 Skyhar MJ, Altchek DW, Warren RF, Wickiewicz TL, OBrien SJ. Shoulder arthroscopy with the patient in the beach-chair position. Arthroscopy 1988;4:2569
4 Friedman DJ, Parnes NZ, Zimmer Z, Higgins LD, Warner JJ. Prevalence of cerebrovascular events during shoulder surgery and association with patient position. Orthopedics 2009;32:256
5 Weber SC, Abrams JS, Nottage WM. Complications associated with arthroscopic shoulder surgery. Arthroscopy 2002;18:8895 5. Pohl A, Cullen DJ. Cerebral ischemia during shoulder surgery in the upright position: a case series. J Clin Anesth 2005;17:4639
6 Bhatti MT, Enneking FK. Visual loss and ophthalmoplegia after shoulder surgery. Anesth Analg 2003;96:899902
7 Papadonikolakis A, Wiesler ER, Olympio MA, Poehling GG. Avoiding catastrophic complications of stroke and death related to shoulder surgery in the sitting position. Arthroscopy 2008;24:4812
8 "President Reviews 2009 Prepares for 2010." APSF Newsletter Winter 2009-2010. [Online] http://www.apsf.org/resource_center/newsletter/2010/winter/02_presreport.htm. Cited 6/11/2010.
9 Lorri Lee, MD and Robert Caplan, MD. SPSF Workshop; Cerebral Perfusion Experts Share Views on Management of Head-Up Cases. APSF Newsletter Winter 2009-2010. [Online] http://www.apsf.org/resource_center/newsletter/2010/winter/01_workshop.htm. Cited 6/11/2010.
About CASMED® - Monitoring What's Vital
The Company's product lines include the high-acuity monitoring capabilities of the FORE-SIGHT Cerebral Oximeter, the bedside patient monitoring line of vital signs monitoring products, proprietary non-invasive blood pressure measurement technology, and supplies and service including blood pressure cuffs and products for neonatal intensive care. CASMED products are designed to meet the needs of a full spectrum of patient populations worldwide, ranging from adults to pediatrics and neonates.
For further information regarding CAS Medical Systems, Inc., visit the Company's website at www.casmed.com.
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