BBI Contributing Editor
ORLANDO, Florida — One of the topics at this year's American Society of Anesthesiologists (ASA; Park Ridge, Illinois), kicked off with the usual day-early refresher courses, was the use of pulmonary artery catheters (PACs) — a subject of interest ever since Journal of the American Medical Association articles in 1996 highlighted the risks and adverse outcomes of their use. Dr. Jeff Vender, professor at Northwestern University's Feinberg School of Medicine (Chicago, Illinois), pointed out several newer articles showing positive outcome differences in patients with pulmonary artery catheters that were properly managed, but qualified his comments by noting some deficiencies in the studies that limited broad generalization of their results. This is of critical importance to companies such as Edwards Lifesciences (Irvine, California), whose PAC business was negatively impacted by the earlier publicity on problems with PACs. Should additional studies continue to support positive outcomes, they could become the basis for a limited resurgence of the use of these devices in certain clinical situations.
The key, as Vender has consistently pointed out, is for clinicians who are using a PAC to know why they are doing the procedure, how to perform it safely and what difference the information will make in the management and outcome of the patient. "Misinterpretation and misapplication of PAC data is an obvious impediment to improved patient outcome and to our ability to demonstrate a clear benefit to PA catheter monitoring," Vender said, suggesting that some indications for PAC use include accessing patient fluid volume status, measuring mixed venous oxygen, determining the (systemic vascular) resistance the heart pumps against and determining and tracking cardiac output.
Amid the disfavor of traditional pulmonary artery-wedging techniques there was no lack of alternative invasive technologies shown during the meeting. Lidco (Coppell, Texas) was showing its PulseCO (Lithium dilution) continuous cardiac output system, which requires only an arterial and venous line but no pulmonary artery line. This is an invasive CO technology being evaluated to replace traditional PAC monitoring. Precision and bias compared to Edwards CCO technologies were performed and reported by John Tollman, MD, of Washington Hospital Center (Washington) in a clinical abstract that was the only new clinical study for this technology reported at this year's meeting.
The Lidco system is but one of three different competing technologies. A new pulmonary artery catheter, TruCCOMS from Aortech (Bellshill, Scotland), was recently introduced into clinical practice. That system uses a thermistor in a small heating coil and measures the energy required to maintain the coil surface at a 1 C differential above the blood temperature. This mechanism of action enables a beat-to-beat update of the cardiac output.
While TruCCOMS' CCO values have been validated against intermittent thermodilution with ice-cold saline, there are currently no data regarding the agreement of those values values with the pulse contour analysis offered by Pulsion Medical Systems (Vista, California). In an abstract studying these two technologies, Berthold Bein, MD, of University Hospital (Keil, Germany) reported good correlation. However, while this would normally clear the way for increased market acceptance of TruCCOMS, just prior to the ASA meeting Aortech reported it was reorganizing due to financial difficulties that developed because of some technical problems with the TruCCOMS technology. This may slow its adoption in the U.S. market, but assuming the technical issues can be worked out quickly, the technology could have a bright future as an alternative to conventional pulmonary artery monitoring.
Looking at all of these technologies, the Pulsion and Lidco technologies seem to be the most likely to quickly emerge as favorites in the U.S. market. Distribution is a key issue, and in this regard Pulsion is the favorite, given the large Philips Medical Systems (Andover, Massachusetts) organization that is selling it in the U.S., as Philips is Pulsion's worldwide marketing partner.
Rivaling these three invasive technologies is the increasing popularity of noninvasive bioimpedance (IAG) approaches offered by market leader CardioDynamics (San Diego, California) and newcomer Sorba Technologies (Brookfield, Wisconsin), neither of which were among the technical exhibitors at ASA. One less-invasive imaging technology, esophageal doppler imaging, is offered by Deltex Medical (Branford, Connecticut). This is a technology that has enjoyed more success in European countries than in America to date. Unfortunately, no new papers reported on this technology at this year's ASA gathering, and it seems to be having trouble gaining critical mass in the domestic market. Another less-invasive hemodynamic technology is the Hemosonic transesophageal ultrasonic monitor by Arrow International (Reading, Pennsylvania). This monitor tracks velocity-time integrals and cross-sectional areas at the same side and time. From this, the monitor calculates blood flow and resistance. Arrow was at the ASA conference, showing this and other products.
Interest continues in oximetry area
While there seemed to be fewer exhibitors at this year's ASA show and no increase in physicians, traffic at some booths was robust during the times when physicians were actually on the exhibit floor. Masimo (Irvine, California) reported taking more than 1,200 leads in the first two days of the conference. There were seven new research papers presented at ASA comparing Masimo SET (Signal Extraction Technology), Nellcor (Pleasanton, California) and other vendors' oximeters in a variety of clinical applications. Fred Robertson, MD, of Children's Hospital (Milwaukee, Wisconsin) presented results of studies comparing Masimo SET and Nellcor oximeters at that hospital, which is a member of the Premier group purchasing organization, with which Masimo has recently signed a distribution agreement. The study concluded, "Both new devices recovered data better than older technology. Although overall agreement between new devices was good, interval analysis showed significant differences at low SIQ and low SpO2. These differences between devices may be clinically significant for patients with low SpO2, such as those with cyanotic heart defects or severe lung disease." As a result, the hospital is switching to Masimo SET in some clinical areas where reduced false alarms and improved motion tolerance is important.
Stephen Barker, MD, of the University of Arizona (Tucson, Arizona) also spoke on new oxygen monitoring developments, highlighting improvements in pulse oximetry and providing a rather sharp criticism of why newer technologies such as in vivo blood gas machines developed in the 1990s were never widely adopted, in spite of proof that they worked. "So why don't we have these types of machines in the respiratory room? It's simple. They didn't succeed because managed care in the 1990s wouldn't pay for them and because there was a reliability problem with the optode."
In commenting on current pulse oximeters, Barker noted the differences among various brands, all of which he continues to test in clinical studies. His work has become foundational for simulation studies and is now well correlated with actual clinical results, which his simulations modeled and predicted.
Others reported on pulse oximetry as well. A paper by Norbert Lutter, MD, of Erlangen University (Erlangen, Germany), studied pulse oximeters on 43 patients receiving electro-convulsive therapy under general anesthesia, finding that the Masimo SET, Nellcor N-395 and Philips CMS oximeters studies all performed acceptably, noting only slight variations among these currently available oximeters. Such results should be encouraging to Nellcor in its ongoing contest with Masimo for clinical validation.
The University of Arizona's Barker also presented the results of his studies on 24 patients undergoing heart surgery on cardiopulmonary bypass. The study collected data during pre-bypass, bypass and post-bypass phases. The data for the oximeters during pre- and post-bypass showed no differences. The data during bypass, however, did show a difference in performance that was notable, with Barker concluding that the Masimo SET oximeter provides more reliable SpO2 data during CPB.
Masimo also used the ASA to introduce its new Rad-9 pulse oximeter. The Rad-9 offers a color LCD display, compatibility with all Masimo sensors, simpler menus but a full range of performance including SpO2 trends in a small package.
The newest battleground in pulse oximetry is the "I'm the fastest-measuring oximeter" space. Since the introduction of Masimo's new ear sensor and its ability to measure desaturations seconds before oximeters using finger sensors (its own or competitors), the speed of measurement is mostly what competitors have been talking about. Nellcor's response was a fast, forehead reflectance sensor, which it showed at the ASA. To make the measurement, Nellcor introduced a new, patented forehead sensor and a new oximeter, the N-595. Masimo also was showing its new reflectance forehead sensor, so 2003 is likely to be orchestrated by continuing claims and counterclaims about whose sensor is fastest, most accurate and has the fewest problems.
Sleep apnea and anesthesia
One important issue emerging in anesthesiology is the special problems associated with providing anesthesia to patients with severe obstructive sleep apnea (OSA). The number of people with undiagnosed OSA is estimated at between 18 million and 40 million, with 95% of sufferers being unaware that they have the condition. Often the first time that these people discover the problem is when they come for elective surgery. Jonathan Benumof, MD, an anesthesiologist at the University of California at San Diego, estimated that 4% of middle-aged men and 2% of middle-aged women have OSA, with one of the biggest risks being obesity. Some 60% to 90% of people with OSA are obese, with the problem expected to grow as the population ages. Benumof noted that the anesthesiologist should postpone surgery until suspected OSA patients are diagnosed and adequately treated.
Most anesthesiologists don't even ask patients in their pre-induction history and exam if they have sleep apnea, or note the answer in their charts. This creates a potential time bomb downstream when patients with severe obstructive sleep apnea have difficulty emerging from anesthesia and reaching stable, auto-breathing status. The failure is generally manifest in the recovery room or even later in the intensive care unit, where the patients can suddenly and rapidly progress into respiratory failure and arrest. That was one of the possible findings of a poster presentation by researchers at the Hoag Hospital (Newport Beach, California), which highlighted the need to use pulse oximetry in post-surgical patients. The Hoag study followed 69 post-major abdominal surgical patients and found 1,300 desaturation events over a two-day period. The researchers used Nellcor oximeters, but did not differentiate between true and false desaturation events.
Benumof also addressed obstructive sleep apnea in the Anesthesia Patient Safety Foundation Newsletter, commenting on previous articles after reviewing 10 cases of adverse patient outcomes. The problem is that in these patients, apnea can result in rapid deterioration, and without being in an ICU, these patients may not be monitored at all, or monitored with stand-alone pulse oximeters and noninvasive blood pressure monitors that do not relay alarms that occur directly to the nursing staff responsible. The answer is continuous etCO2 and SpO2 monitoring of these patients using a wireless LAN to provide continuous surveillance at a centralized location staffed by qualified caregivers, at least registered nurses (RNs).
Nellcor provides such a wireless LAN network with its Oxinet II remote central station and its In-Touch RN Paging system that alerts nurses on alarm, but the key is to assess these patients and intervene before a patient's condition deteriorates to an alarm (and crisis) situation. The impact of the RN shortage on being able to do this, and the general lack of knowledge of many general ward RNs about etCO2 monitoring, makes this both an ongoing challenge and quality issue. Certainly it will be an area for ongoing litigation when avoidable patient arrests occur, as the central network will document the trends and earlier hallmarks which the nursing staff either doesn't recognize or fails to respond to. Ultimately however, it may be the anesthesiologist who is sued, particularly if the patient history and chart from pre-op does not contain data about the patient's history of sleep apnea. This could be considered negligence if such relevant information is omitted from the chart.
Capnography is clearly a vital parameter during anesthesia, but it also is in many other clinical settings. Oridion (Needham, Massachusetts) exhibited its improved and innovative technology. In a paper comparing Datex-Ohmeda (Madison, Wisconsin) and Oridion capnometry on patients receiving anesthesia by nasal canula during office-based gastrointestinal (GI) procedures, Dr. Krutsch of the University of Colorado (Boulder, Colorado) reported that the Oridion technology was significantly more reliable on difficult, obese patients than the Datex-Ohmeda technology for the 30 patients that were studied. The Oridion capnography is able to use a unique nasal sensor and would provide advantages for interventional GI radiology procedures in physician office settings. This improved Oridion etCO2 technology is offered by several of its OEM partners and certainly appears to be the technology of choice, although many competitive technologies exist and are in wider use at the present time.
Alliances impact gas machine sector
Anesthesiologists, like emergency room physicians, will be on the front lines in the event of a biological, chemical or terrorist attack, and that point hasn't escaped the Anesthesia Patient Safety Foundation (Pittsburgh, Pennsylvania) or the ASA. A key question in the event of such an occurrence is, "Will there be enough anesthesiologists and medical monitors available to respond adequately?" A study by Gifford Eckhout, MD, of the Cleveland Clinic (Cleveland, Ohio) reported that, as of this year, there is a shortage of anesthesiologists of somewhere between 3% and 11% of total supply. The study projects that a shortage in the range of 1% to 10% will continue through 2005. These conclusions were detailed in an abstract presented at the conference. How will this shortage be accommodated? One possibility is greater use of nurse anesthetists, but that is something that the ASA has historically lobbied against in Congress. The battle between the anesthesiologist and nurse anesthetist lobbies is one of the more spirited clashes in the medical/legislative arena.
Whoever is behind the gas machine controls is going to have to manage more patients, and this has implications for vendors of monitors, gas machines and other perioperative technology. Future systems must be both more foolproof and simpler-to-use, more intelligent, more integrated — actively assisting the user to a diagnosis of problems which develop in the system, rather than simply presenting alarms and depending upon the user to troubleshoot complex anesthesia systems. Perhaps with this in mind, both of the two major suppliers of anesthesia machines in the U.S. market — Datex-Ohmeda and Drager (Telford, Pennsylvania) — have recently become aligned with monitoring suppliers, and have begun to more actively integrate their partners' patient monitors into their gas machines, at least for their high-end, most sophisticated products. In fact, Drager and Siemens Medical Solutions (Danvers, Massachusetts) have proposed a joint relationship (two-thirds of which is owned by Drager) in which Drager will show its gas machines with integrated Siemens' monitoring equipment in the domestic market. Of course, their gas machines will continue to support the use of other vendors' monitors as well. Datex-Ohmeda, once Philips' OEM partner (and Hewlett Packard's in an earlier existence), then jumped to partnering with GE Medical (formerly Marquette Medical; Milwaukee, Wisconsin) and now has settled on a third alliance. But like rival Drager, the Datex-Ohmeda gas machines will work with other monitoring system vendors as well. There simply are not enough prominent gas machine suppliers to go around for the myriad of monitoring vendors looking for a partner.
This arrangement leaves first-tier competitor Philips without a formal gas machine partner, as it has with all of the second-tier companies that currently offer monitors and anesthetic agent ID and tracking systems. Datascope (Mahwah, New Jersey) has begun to offer its own gas machine in the U.S. market and Penion Ltd. (Abingdon, UK) was at ASA looking for a U.S. partner, but also realistic about its chances of obtaining any significant market share against the two U.S. market leaders. Even with a good product, it is difficult to see how any newcomer without U.S. brand recognition can eke out a significant market share.
At least one non-U.S. vendor, Schiller (Baar, Switzerland), has decided to enter the U.S. patient monitoring and diagnostic device (ECG, etc.) market in a big way. Schiller showed a family of monitoring and perioperative products at ASA, as well as products for cardiology and intensive care units. According to its president, Andrew Jobson, Schiller plans to enter the U.S. market, establish a direct sales organization and become a competitor across almost all hospital-based market segments, including some niche segments, such as magnetic resonance monitoring. Jobson is the husband of Joanna Jobson, Datex-Ohmeda's monitoring sales manager, so this will pit husband and wife in competing marketing roles at competing companies, an unusual arrangement in the U.S. market at least, unless there ends up being some sort of marketing arrangement between Datex-Ohmeda and Schiller.
However, Schiller's relationship with Drager in non-U.S. markets and the need for Datex to digest Spacelabs Medical (Redmond, Washington), which it acquired not long ago, would seem to argue against such an alliance. Undaunted by the success of Invivo Research (Orlando, Florida) in the magnetic resonance (MR) monitoring arena, with an 80% U.S. market share that has diminished or vanquished such U.S. competitors as MedRad (Indianola, Pennsylvania) and Datascope, which represented MR monitors produced by Bruker in the U.S. market, Schiller is offering its own MR monitor as part of its new U.S. presence. With Schiller entering the space vacated by Datascope, only MedRad and its Model 9500 vital signs monitor are left to compete for the U.S. MR monitoring business.
Schiller does not seem to be concerned either about side-by-side demonstrations of its Maglife C Plus MR monitor (for use in MR areas with field strengths up to 3 Tesla) with Invivo's Magnitude monitor (also a 3 Tesla-qualified monitor). Schiller privately showed us a letter from one well-known Midwestern site that had evaluated both systems and wrote Schiller to commend it on its superior performance. Yet Invivo has a commanding lead and announced at the ASA gathering that Drager will provide the Magnitude AS gas machine equipped with the Invivo Magnitude MR monitor as its offering to MR suites where patients require conscious sedation. Drager's partner for such systems in Europe and certain other non-U.S. markets is none other than Schiller. So there now appears to be some aggressive new competition in this niche segment that Invivo previously had almost exclusively to itself. And Drager's isn't the only MR-compatible gas machine available in the U.S. market. Dre Inc. (Louisville, Kentucky) is offering its Integra SP gas machine, which can be used in some MR imaging areas.
Consciousness monitoring via bispectral index (BIS) and audio-evoked potential monitoring continued to be a topic of interest, with no fewer than 72 new papers presented on the technology at this year's ASA gathering. Due to its adoption and growing use, BIS has been and continues to be studied in many clinical settings on patients with a wide variety of clinical conditions. Aspect Medical (Newton, Massachusetts) is the market leader, well ahead of competitors such as Physiometrix (North Billerica, Massachusetts) and Alaris (San Diego, California), who offer technologies with very little U.S. installed base.
Yet the interest in BIS is quickly shifting away from the perioperative space into the ICU, where conscious sedation of ventilated patients for days (rather than hours in the operating room) afford much greater benefits in sparing use on expensive anesthetic agents and reducing length of stay, thus saving money to offset the $15 to $20 the BIS sensors add to the cost of managing the patient. BIS modules also are being added to gas machines, as we saw a BIS XP S/5 module in a Datex-Ohmeda machine at ASA. Aspect Medical, the sole viable competitor offering this, continues to struggle as sales of stand-alone units in anesthesia have dropped before the corresponding sales of individual modules in the monitoring vendors' systems have ramped up to replace them. The company now is almost totally dependent upon sensor revenues for growth, which has caused stagnation in revenues (revenues for the last two years were essentially flat) and fr 2002 will most likely end up in the mid-$40 million range, far less than the $75 million needed for the company to be profitable. The bright spot is the ICU and conscious sedation arena, which now accounts for a significant and growing percentage of total revenues. Meanwhile, some of the research reported indicates a few issues remain to be addressed.
An interesting study performed by Craig Weldon, MD, et. al, at the University of Florida (Gainesville, Florida) was presented at ASA. This research tested the "I can fly blind" hypothesis and established a dramatic outcome. Weldon did a prospective study of 907 patients designed to evaluate the relationship between depth of anesthesia as measured by BIS (but blinded to the anesthesiologist) and one-year survival. Until this study, little research had addressed the possibility of the depth of anesthesia affecting patients' long-term outcome or survival.
BIS was recorded for each of the 907 patients undergoing general anesthesia procedures lasting two hours or more. Exclusion criteria included altered mental capacity, patients undergoing cardiac or intracranial surgery, drug abuse, and disorders of the central nervous system. Interestingly, the BIS was blinded to the anesthesia provider throughout the case and anesthesia was maintained using traditional indicators of anesthetic depth. All patients received general anesthesia but the anesthetic technique was not standardized.
The results demonstrated that there was no difference in baseline BIS levels between survivors and non-survivors. However, mortality tended to be higher if the BIS levels were less than 40 in patients 40 years and older — increasing age and lower BIS scores were both independently associated with higher mortality rates.
Masimo has taken a different approach to the ICU use issue. By making its Radical series oximetry interface directly into an existing vendor's patient monitors (in essence the whole oximeter is seen by the patient monitor as a sensor and not an oximeter), that company is able to leverage the existing patient monitoring system rather than creating a separate one for oximetry alone. Masimo has interfaced to 13 different vendors' systems, including Nellcor's. This is a preferable approach in the intensive care unit, but in a general ward where no such system is installed, it has its limitations compared to the Nellcor approach.
Alliances, new monitors, AIM efforts
In this era of continued market consolidation, in addition to the actual acquisitions and mergers of competitors, there are a growing number of marketing alliances. The Drager-Siemens partnership, which at the time this was written was still pending U.S. regulatory approval, will feature Drager integrating Siemens monitors on its gas machines and representing Siemens in the perioperative monitoring space in the U.S. Drager also will be integrating its MR-compatible Magnitude AS with Invivo's Magnitude monitoring in the U.S., but with Schiller's monitors in several non-U.S. markets.
Some marketing alliances seem to be fragile. Welch Allyn Protocol, a Masimo OEM partner, has nonetheless integrated Nellcor pulse oximetry into a new version of its Micropaq wireless, patient-worn monitor product, a product that previously offered Masimo SET oximetry exclusively. This new version was a bow to market barriers by some hospitals that purchase only Nellcor-based oximetry products. Such non-compliance by Welch Allyn is unlikely to affect Masimo substantially, because even though Welch Allyn's wireless Micropaq sales have increased dramatically relative to its previous wireless sales, the Micropaq still represents less than 2% of the telemetry monitors installed in the U.S. market. With larger competitors such as Datascope and GE Medical Systems Information Technologies (Milwaukee, Wisconsin) firmly committed to Masimo, and with Masimo's recent penetration of key group purchasing organizations, how compliant companies like Welch Allyn actually are to their OEM contracts will not be of major impact.
Philips' Intellivue Model 70, introduced in July, was joined by the new Model 90, which we saw for the first time at the ASA conference. The Model 70 is most comparable to the GE 8000 series, while the Model 90 is most comparable to the GE 9500 series. These monitors offer a unique Ethernet networking scheme that assures real-time transmission of waveform, alarms and vitals, but uses Citrix and some networking slight-of-hand to maintain background call-up of ECG + lab + web + imaging or other applications needed at each bedside. The details that impressed us about both of these new models included limited depth and relatively easy-to-use menu structure; the unique combination of a twist knob, pointer and joystick in one integrated control; the alternatives of touch screen and the ability of the user to use a mouse, track ball or whatever interface is most convenient. The ability to flexibly configure the monitor, as well as its ability to store and recall a wide variety of user-defined configurations, will make these new members of the next generation of Philips' monitors work conveniently in any clinical setting. The sharp display and high screen resolutions provide all the resolution needed for DICOM image displays, recall of 12-lead diagnostic ECG annotated with analysis from either an HP or a GE Medical computerized ECG management system, or the recall of moving ultrasound or video images from other picture archiving and communications or radiology systems. Coupled with call-up of lab results and remote access to Internet-based medical data repositories, these new bedsides can truly be described as point-of-care monitoring and clinical workstations.
Since announcing a year ago that it expects the anesthesia record to become electronic and computerized within five years as a standard of practice, during the last 12 months the Anesthesia Patient Safety Foundation has worked quickly and diligently with all interested anesthesia information systems (AIM) vendors to establish the necessary common terminology or data dictionary for perioperative charting so that outcomes can be described and tracked. The APFS data dictionary task force was led by Terri Monk, professor of anesthesiology at the University of Florida (Gainesville, Florida). A data dictionary was deemed a mandatory prerequisite for collecting data necessary to analyze data outcome questions and establish best practices in anesthesiology.
The anesthesia data dictionary developed by APFS has been submitted to SnoMed, and is expected to be included by that group as part of its growing terminologies for various practice settings. The availability of the APFS terminology is important because AIM vendors who are quick to adopt and integrate this terminology will have a significant advantage over those who do not, an advantage that can translate into fewer sales objections and increased sales. Having integrated the APFS data dictionary, it is hoped that the adoption of AIMs will now be expedited and accelerated so that the current 5% of U.S. hospitals that use such systems will rapidly increase, which should assist a number of vendors offering such systems.
Another step to improving quality and minimizing errors is the barcoding of drugs dispensed. The FDA kicked off the move to barcode drugs when it issued a statement in the Federal Register in June stating that barcodes could make a contribution, and promoted the tracking of the right patient, right drug, right route, right time of administration on drugs. Since then, Abbott Laboratories (Abbott Park, Illinois) has begun microcoding its drugs and B. Braun Medical (Bethlehem, Pennsylvania) also has responded with its Horizon Outlook IV safety system and DoseGuard software. Horizon uses barcode technology to program the pump. Adoption of barcoding by drug suppliers would further eliminate the need for manual labeling of drugs being administered. Alaris Medical also offers dosing safety software, but was not among the vendors exhibiting at ASA. And most recently, Baxter (Deerfield, Illinois), which was at ASA, announced a barcode initiative.