Cause of Device-Related Incident
*Not stated

Clinical Specialty or Hospital Department
CCU / ICU / NICU; Home Healthcare; Nursery

Device Factors
*Not stated

Document Type
Guidance Articles

External Factors
*Not stated

Mechanism of Injury or Death
Monitoring failure

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
*Not stated

UMDNS
Apnea Monitors [12-575]; Apnea Monitors, Recording [17-885]; Impedance Pneumograph Monitors [12-621]

Issues in Selecting and Using Apnea Documentation Systems



Guidance [Health Devices Oct 1992;21(10):374-9]

The primary purpose of apnea monitoring is to ensure adequate warning of certain life-threatening respiratory and cardiac events, often in infants monitored at home. However, parents often become frustrated by frequent alarms, and others may not use the monitor at all. Unfortunately, ECRI has received a number of incident reports in which infants have died while not connected to their monitors or where a failure to monitor was suspected. We believe that some of these deaths may have been prevented if monitoring had been used properly.

The most important step that parents can take to achieve effective monitoring is to faithfully follow the directions of their doctor. In an effort to ensure parental compliance, documentation capability has been added to many of today's monitors. In addition, those involved in providing patient care, especially the prescribing physicians, durable medical equipment (DME) providers, report scorers, interpreting physicians, and other clinicians, should carefully review their monitoring programs and the available documentation monitoring systems to determine how they can best meet their patients' needs. Below, we discuss the factors to consider when contemplating documented apnea monitoring and when selecting a documented monitoring system.

The Use of Documented Monitoring

Advantages of Documentation Systems

Documented monitoring offers distinct advantages over nondocumented monitoring. Its most important benefit is that it can be used to confirm parental compliance and reveal whether steps must be taken to improve it. It also provides evidence of the time and type of alarms, and the tabular and waveform reports provide physicians with information about a patient's condition that would not be verifiable with conventional apnea monitors. Waveform documentation helps physicians to more accurately distinguish true from false alarms and assess the severity of events.

Documentation can also provide early warnings of monitoring problems, as well as vital information for investigations and research in the event of an infant death. And the use of documentation systems has the potential to reduce the cost of patient care by providing additional criteria for admission to and discharge from apnea programs and also through reduced trips to patients' homes to resolve problems. However, no studies have yet verified that either conventional apnea monitors or documentation systems improve the quality of patient outcome.

Safety Features and Practices

Purchasers should inventory their existing monitors to determine whether they have the essential safety features: heart-beat detectors with heart-rate alarms, remote-alarm capability, power-loss alarms for non-battery-operated units, and electrodes that cannot be plugged into electrical cords or outlets. Any monitor being considered for purchase or currently in use that does not meet these minimum criteria for safety should be replaced as soon as possible.

ECRI recommends that, at a minimum, compliance monitoring be used during the first few weeks of the monitoring period for all patients, and we prefer that documented monitoring be used throughout the monitoring period. In many cases, physicians prescribe full-time compliance monitoring (i.e., monitor on and off times) only when compliance is questionable, rather than routinely prescribing it for every patient. However, if money is an issue and no problems are found, switching to nondocumented monitoring is reasonably safe, as long as compliance and reporting are ensured. In hospitals, compliance monitoring is not as critical because hospital staff will more reliably follow the physician's orders. Unfortunately, we are not aware of any simple, low-cost add-on device that can be used in conjunction with existing conventional apnea monitors to add basic documentation capabilities, such as compliance monitoring.

Selection Factors for Apnea Documentation Monitors

Because no exact method or standard criteria for apnea monitoring yet exist (see Health Devices Oct 1992;21(10):339-41), ECRI believes that greater monitoring capabilities and features (i.e., more channels and complete waveform and tabular documentation) provide clinicians with greater flexibility, which may lead to better patient management. Although greater capabilities may allow more information to be collected, this is an advantage only if the information will be used. Purchasers should therefore consider the available resources and anticipated use of these capabilities when making purchasing decisions. Below, we discuss various selection factors for apnea documentation systems and the relative merits and shortcomings of various capabilities and features. Also see "The FDA Apnea Monitoring Standard" at the end of this article.

Patient Population

Most home apnea monitoring programs are limited to infants. However, some programs include older children and adults. The needs of older patients, especially adults, are different from those of infants, and these needs should be considered in the purchasing process. For example, some adults are monitored at home because they are receiving patient-controlled analgesia (PCA), and some PCA drugs are respiratory suppressants that can significantly slow breathing. Also, many patients (usually adults) are sedated while in the hospital. In these cases, units that alarm and document slow breathing have advantages over other systems.

It is well recognized that impedance pneumography (IP)-based apnea monitors are unable to detect obstructive apnea. Unfortunately, because most adult apnea is obstructive, techniques other than, or in addition to, IP must be used to effectively monitor and record apneic events in adults. Two possible methods are nasal airflow and pulse oximetry (see below).

Monitor Performance and Impedance Pneumography

Although monitoring performance was not the focus of this evaluation of IP-based systems, as it was in our previous study (Health Devices 16[3-4], Mar-Apr 1987), we noted that monitor performance does not appear to have changed significantly over the past five years. As in our last evaluation, most of the monitors in this study worked well most of the time. However, some more than others easily went into or out of alarm status in the presence of aberrant signals. The most serious limitations of IP are that it cannot detect the loss of airflow (obstructive apnea), and it may interpret thoracic movements and other artifacts unrelated to respiration as breaths. However, IP apnea monitoring is still the easiest, most practical method of detecting apnea in the home.

Recording Modes

Although the Event mode of recording is a useful compromise between the need for patient data and the need for memory conservation, it is subject to the shortcomings of IP. Apnea monitors using IP technology do not detect all significant patient events and do not work 100% reliably on all types of patients. Therefore, documentation is not always an accurate representation of patient conditions.

Because some clinicians may tend to trust computer-generated hard-copy information more than they do the parent's log or other account, the documentation now produced by apnea systems may offer a false sense of security in monitor performance that never existed in the past. Tabular data (without waveforms) provides only a thorough chronology of alarms and events; it does not allow the user to verify the accuracy of the recording of the event (e.g., to determine whether an apnea alarm was due to a valid apneic episode or to an artifact). Neither tabular nor waveform Event mode recording can ensure that a patient event was not missed. However, for those well versed in the applications of IP in apnea monitoring, documentation has helped to heighten their awareness of the shortcomings of this technology by giving them insight into what occurred during alarms.

Memory Management and Capacity

Memory management and memory capacity should be fully investigated and understood before selecting a documentation system. Monitoring system memory management methods must be in agreement with the view of data priority adopted by the apnea program. Because of electronic memory limitations and the associated cost factors, each monitor manufacturer has to compromise the duration, quantity, and types of events kept in memory.

The waveform-documentation systems manage memory in one of three ways:

  • First-in-first-out (FIFO). These systems keep the most recent data and overwrite the oldest data. ECRI believes that this helps to maintain trending information that is the most relevant to the patient's current condition; this is in agreement with the general philosophy of trend monitoring. We prefer this approach.
  • Halted recording. These systems stop recording waveforms when the memory fills. These systems are an alternative to FIFO systems and present no increased risk of inappropriate data loss with sufficient memory capacity; also, some physicians prefer to retain the data obtained at the start of the monitoring session.
  • Prioritization. These systems keep events that satisfy specific criteria based on the duration of events. This is the least appropriate method of maintaining patient data, primarily because longer heart-rate events are not necessarily the most severe. Although, theoretically, longer respiratory events can be the most significant, this is not always true because of the shortcomings (e.g., changes in transthoracic impedance [TTI] due to body movements) of IP-based apnea monitoring in the home.

Note that routinely downloading data will ensure that the effects of any memory management method will cause minimal loss of data.

Total waveform time (TWT) is not an absolute measure of which memory system will record more events on a given patient. Actual recording durations vary in the clinical setting. However, during our testing of waveform-logging systems, we did find that TWT is a general indication of recording duration because those systems with the smallest TWT capacities consistently filled first.

During our discussions with clinical users, we found that event and waveform memory-related problems and inconveniences are rare. However, all of the currently available methods of memory management are subject to the loss of data. Trade-offs must be made between the type (i.e., tabular or waveform) of documentation, number and duration of events, system cost, system speed, and memory capacity. Again, the method of memory management selected should be consistent with the goals of the specific apnea monitoring program.

While a capacious memory may seem highly desirable, it is not usually necessary. Apnea monitoring in the home requires personal attention from DME providers. Memory should be considered sufficient if it can record without losing valuable data between visits by the DME; memory capacity limitations should not result in the need for more frequent visits. The frequency of home visits should be based on patient and family needs, independent of documentation features. Documentation should not be viewed as either a substitute for or a cause for increasing the periods between routine home visits. Remote downloading and alarm and event-limit control are useful features when long distances or time limitations may make it more efficient to carry out these functions from a central location.

Cost Factors

Reimbursement and System Configuration

Cost factors, especially reimbursement, will have a significant effect on which, if any, documentation systems are acquired. Those responsible for apnea monitoring programs must have a clear understanding of reimbursement in their area before making purchasing decisions. Some DMEs receive additional reimbursement for documentation monitors over that received for nondocumentation monitors. Some receive no additional reimbursement, and others receive reimbursement for only nondocumented monitoring when periodic documentation studies are performed as proof of the need for monitoring. Reimbursement also varies from region to region. Where reimbursement levels are high, DMEs tend to convert a large percentage of their monitor line to documentation systems; as reimbursement levels degrade, so does the willingness or ability to convert to these systems.

One approach to updating apnea monitoring equipment in light of limited reimbursement is to minimize the major cost factors. For example, for systems that require a computer, purchasing an IBM clone, upgrading an existing underutilized computer, or sharing an existing office computer may help to reduce the computer-related expenses. Also, the DME's labor costs can be reduced by reducing the amount of data recorded after the initial monitoring period; for example, some monitors allow portions of the memory to be turned off. Another approach is to distribute the cost over an extended period. For example, tabular-logging systems are generally less expensive to purchase and operate than waveform-logging systems. Tabular reports may provide enough documentation to satisfy insurance companies' requirement for proof of the need for monitoring and to verify compliance. If physicians prescribe waveform-documentation systems, DMEs can acquire them gradually. It is also important to anticipate upgrading or expanding the documentation capabilities of an apnea program. Some manufacturers offer a trade-in value for their own nondocumentation monitors toward the purchase of documentation monitors. Time and money can be saved when purchasing tabular- and waveform-logging monitors that can be used with the same computer software.

Some systems can directly print tabular event reports without a computer and its associated costs. Before purchasing a computer for use with a documentation system or a documentation system for use with an existing computer, purchasers must confirm that they are compatible.

Some manufacturers of documentation systems also offer nondocumenting apnea monitors. Existing nondocumenting monitors in inventory may influence a DME's decision about which documentation systems to obtain. Apnea programs that are already using one manufacturer's apnea monitors will have to consider whether purchasing documentation monitors from another manufacturer will affect parents by creating confusion in learning and becoming familiar with new monitors. Also, the DME's learning curve, confidence level, physician familiarity, and costs must be considered.

Levels of Documentation

Systems with the most documentation capabilities have the potential to be the most clinically useful and are preferred, especially in areas where reimbursement is adequate.

Four levels of waveform documentation are available:

  • Level 1. The most complete level of documentation is event recording of respiration and ECG waveforms and heart-rate trend during respiration and heart-rate events.
  • Level 2. These systems contain the same channels as level 1, but ECG waveforms are recorded only during a maximum of 10 heart-rate events.
  • Level 3. ECG waveforms are recorded for only a 15 sec portion of heart-rate events.
  • Level 4. These systems contain the least amount of documented waveform data currently available—respiration waveforms and heart-rate trend.

As noted above, although waveform systems can be used to satisfy clinical preferences and answer many questions, they may be more expensive to purchase and operate. Alternatively, tabular documentation systems may cost less initially and can be less complex to operate. They meet the basic needs of compliance, in some cases without a computer, and allow verification of the presence of alarms (although not their validity) without having to rely entirely on the parents' log. However, the initial cost difference between waveform and tabular documentation systems may be under $500, which may not be significant when distributed over the life of the device.

Additional Capabilities and Considerations

Pulse Oximetry

Blood (hemoglobin) oxygen saturation, or SpO2, can be used by physicians to help determine the severity of a patient's condition. Pathologic conditions related to low blood oxygen saturation may in some cases be related to apnea. Oxygen saturation can be monitored noninvasively using a pulse oximeter. Some of the apnea monitor manufacturers offer their own pulse oximeters, and most apnea monitors are compatible with pulse oximeters from other manufacturers. However, at this time, pulse oximetry should be given limited weight when selecting a documentation system.

The oximetry-derived oxygen saturation of hemoglobin value can be documented as a number (SpO2), or it can be represented by a line indicating SpO2 over time (i.e., a trend). One difficulty in documenting pulse oximeter data is the errors that can occur from signal artifact (e.g., from probe movement) and frequent alarms due to excessive motion, which can rapidly fill the monitor's memory. To partly compensate for these problems, all of the evaluated monitors provide some indication of pulse oximeter artifact if an error is suspected. This increases the utility of this SpO2 documentation. Oximetry-derived pulse waveforms may be used to verify the validity of oximeter alarms through a manual comparison of ECG and pulse waveforms.

Although oxygen saturation is valuable data, especially in view of the shortcomings of the IP technology, monitoring SpO2 is expensive and is difficult to reliably obtain on infants in the home because of its susceptibility to false alarms. In addition to unnecessarily upsetting parents, false alarms may fill event memory, requiring more frequent data downloads or loss of important events.

Systems that perform error checking on the SpO2 data are the only type that should be considered for home use. Systems that can be triggered to alarm or record events by the oximeter are preferred; several of the manufacturers participating in our study offer these features with their own oximeter.

Pulse oximetry should be used only in cases when not having the SpO2 data will do more harm than the possibility of false alarms. SpO2 is typically used in 10% or less of home monitoring applications with IP. Although some clinicians prefer pulse oximetry data, ECG waveform data is currently the most practical and cost-effective additional data that can be obtained in apnea monitoring programs.

ECG Waveforms

As noted above, the ability to document ECG waveforms is a significant advantage. Some clinicians use ECG waveforms to help determine the validity of patient events and to determine the nature of aberrant signals. However, ECG waveform data is not generally viewed as a direct indicator of event severity (SpO2 is a better indicator of severity than ECG, but ECG is easier to detect reliably in the home; see below). It also consumes much memory and can increase the time required to download, transmit, and print waveform reports, and it requires more time for analysis. ECG data also increases the frequency of downloading monitor memories. The ability to select ECG waveform recording or to turn it off is therefore an important option for this feature.

Periodic Breathing (PB)

Some apnea monitoring programs and monitoring devices identify and classify PB as a specific type of respiratory event. Breathing is classified as periodic if it contains three or more pauses of greater than 3 sec that are separated by less than 20 sec of normal respiration. However, this is a strict definition, and, as with most patient data, PB must be evaluated on an individual basis.

Alarming on and documenting PB is not generally considered useful, primarily because individual breathing patterns vary widely. PB is more useful with waveform capture so that clinicians can evaluate the event for themselves. However, few clinicians use the PB function. Also, PB is a long event and consumes much memory, which limits the amount of other waveform information that can be stored; therefore, it may be useful to be able to turn off this feature.

Slow Breathing

The ability to detect and document slow breathing rates is a valuable tool for treating patients (usually adults) undergoing drug therapy, whether using PCA at home or being sedated in the hospital, that can cause respiratory suppression. Therefore, the ability to document slow breathing waveforms is a preferred feature in adult applications. However, slow breathing alarms can be excessive in infants and can cause the memory to fill prematurely.

Other Channels

Today [1992], auxiliary input channels for airflow temperature, CO2, and pH are seldom used in the home because of their limited practicality Separate electronic modules (i.e., nasal thermistors, capnometers, and esophageal probes) are required, and these usually do not have alarms. Although data from these separate modules can be documented on some systems, they can trigger an alarm or event recording only if they have the appropriate output signals and the monitor has separate inputs.

Human Factors Design

Human factors design—including report presentation and software operation and features—is very important in many aspects of apnea monitoring and documentation system selection.

Tabular Report Presentation

Criteria

  • Tabular reports should be well organized and should also have the following:

Good text print quality;

Patient identification, report date, and page number on all pages;

Complete tabular report of patient alarms and events, equipment alarms, and time and date of each occurrence; and

The ability to customize the report content (e.g., inclusion of physician's name, drug therapy, and pie charts) may be useful for some users.

Waveform Report Presentation

Criteria

  • Waveform tracings and trends must have good quality, organization, and layout and should meet the criteria for tabular report presentation.
  • In addition, they must also have the following:

Horizontal scales that permit viewing of individual breath and ECG waveforms;

Vertical scales that can accommodate the required range of signals;

A minimum pre-event waveform time equal to or greater than the alarm delays;

Post-event waveform selection of at least 15 sec (preferred); and

Indicators (i.e., markers on graph) for the start and stop of alarms and events.

  • Event parameters should be on the page with the waveform, including event identification or number, type, time, and duration, as well as calculated physiologic values.
  • Adjustable horizontal and vertical scale control for waveforms is preferred to make interpretation easier.

Software Operation and Features

Criteria

  • The software package should be easy to install. The entire procedure should be clearly documented.
  • The system should be easy to learn and use, even with little or no computer experience. It should not be necessary to frequently refer to the manual for instructions.
  • Help screens and prompts should be available at all levels of the program.
  • The software should supply the computer operator with all the necessary tools to download, view, print, and store patient data efficiently.

Portability

Criterion

  • When packaged for transport, the monitor should not be unwieldy to carry.

Bibliography

Adams JA. Monitoring respiration in the neonate. Neonatal Intensive Care 1992 Jan-Feb;5(1):10-3.

Ahmann E, Wulff L, Meny RG. Home apnea monitoring and disruptions in family life: A multidimensional controlled study. Am J Public Health 1992 May;82(5):719-22.

Association for the Advancement of Medical Instrumentation (AAMI). Apnea monitoring by means of thoracic impedance pneumography [Technical Information Report]. Arlington, VA: AAMI, 1989.

Desch LW, Corkins MR, Blondis TA. Evaluation of changes made to an infant home apnea monitoring program in response to findings from a national consensus panel. J Perinatol 1990;10(4):380-5.

ECRI. Infant apnea monitors [evaluation]. Health Devices 1980 Aug-Sep;9(10-11):247-83.

ECRI. Infant apnea monitors [evaluation]. Health Devices 1974 Nov;4(1):3-23.

ECRI. Infant home apnea monitors [evaluation]. Health Devices 1987 Mar-Apr;16(3-4):79-109.

Finer NN, Barrington KJ, Hayes B. Prolonged periodic breathing: Significance in sleep studies. Pediatrics 1992 Mar;89(3):450-3.

Gilmore A. Apnea monitors of little use in preventing SIDS, experts say. Can Med Assoc J 1989 May 1;140(9):1072-6.

Graff M, Goldie E, Lee G, et al. The four-channel pneumogram in infants with recurring apneas and bradycardias. J Perinatol 1991 Mar;11(1):10-4.

Guntheroth WG, Spiers PS. Sleeping prone and the risk of sudden infant death syndrome. JAMA 1992 May 6;267(17):2379-82.

Kelly DH, Pathak A, Meny R. Sudden severe bradycardia in infancy. Pediatric Pulmonology 1991;10(3):199-204.

Meadows W, Mendez D, Lantos J, et al. What is the legal "standard of medical care" when there is no standard of medical care? [abstract]. Neonatal Intensive Care 1992 May-Jun;5(3):43.

National Institute of Child Health and Human Development, Sudden Infant Death Syndrome Research Program. Sudden Infant Death Syndrome Amendments of 1979 (P.L. 96-142). Fiscal year 1991 report to Congress.

National Institutes of Health, U.S. Department of Health and Human Services. Infantile apnea and home monitoring. [Consensus Development Conference Statement]. 1986 Oct 1;6(6). NIH publication no. 87-2905.

Ruggins NR, Milner AD. Site of upper airway obstruction in preterm infants with problematical apnea. Neonatal Intensive Care 1992 Mar-Apr;5(2):16-21.

Schectman VL, Harper RM, Wilson AJ, et al. Sleep apnea in infants who succumb to the sudden infant death syndrome. Pediatrics 1991 Jun;87(6):841-6.

Southall DP. Role of apnea in the sudden infant death syndrome: A personal view. Pediatrics 1988 Jan;80(1):73-84.

Spitzer AR, Fox WW. Infant apnea. Pediatric Clinics North Am 1986 Jun;33(3):561-81.

Steinschneider A. Prolonged apnea and the sudden infant death syndrome: Clinical and laboratory observations. Pediatrics 1972 Oct;50(4):646.

Steinschneider A, Santos V. Parental reports of apnea and bradycardia: Temporal characteristics and accuracy. Pediatrics 1991 Dec;88(6):1100-5.

The Sudden Infant Death Syndrome (SIDS) Alliance. In response to recent infant sleep position recommendations, the SIDS Alliance urges U.S. commitment for increased SIDS research [media alert]. Columbia, MD: The SIDS Alliance, 1992 May 5.

Taylor RB. Growing pains. Continuing Care 1991 Jun;10(6):18-22.

Weese-Mayer DE, Brouillette RT, Morrow AS, et al. Assessing validity of infant monitor alarms with event recording. J Pediatr 1989 Nov;115(5):702-9.

Weese-Mayer DE, Morrow AS, Conway LP, et al. Assessing clinical significance of apnea exceeding fifteen seconds with event recording. J Pediatr 1990 Oct;117(4):568-74.

Wegman ME. Annual summary of vital statistics—1990. Pediatrics 1991 Dec;88(6):1081-92.

Wilson AL, Stevens DC, Becker BK, et al. Mothers' behavior with home infant apnea monitors. Neonatal Intensive Care 1992 Jan-Feb;5(1):41-9.

* * *

The FDA Apnea Monitoring Standard

Scope and Status

The 1976 Medical Device Amendments to the Food, Drug, and Cosmetic Act charge the Food and Drug Administration (FDA) with the responsibility of regulating the safety and efficacy of medical devices and diagnostic products. One means by which this responsibility is met is through the preparation of product standards by FDA's Center for Devices and Radiological Health (CDRH).

Apnea monitors are in a high-priority category for standards because of the risks and hazards associated with them. In 1986, FDA undertook efforts to establish standards to improve the safety and effectiveness of apnea monitoring. To date [1992], it has issued two drafts of "The Standard for the Infant Apnea Monitor." The standard covers requirements for all monitoring modalities in home and hospital infant apnea monitors, including performance features, labeling, and test procedures.

The third draft of the standard is expected to be entered into the Federal Register as a proposed rule sometime in 1992. If this does happen, it will take several more years for finalization and phase-in. FDA estimates that the soonest the final rule would take effect is mid-1995.

FDA and AAMI Cooperation

FDA has been working in consultation with the Apnea Monitoring Committee formed by the Association for Advancement of Medical Instrumentation (AAMI). The committee comprises manufacturers, physicians, and apnea professionals and is subdivided into task groups. These groups focus on different monitoring modalities, such as impedance pneumography (IP), inductive plethysmography, and pulse oximetry.

The committee is currently working on devising an apnea monitor test method; this method is designed to use a database of recorded physiologic waveforms. All meetings are open to interested parties, and participation is encouraged.

Impact

Once the standard is entered in the Federal Register and becomes a final rule, monitor manufacturers will have about one year to phase in the required changes to their apnea monitor systems. All monitors sold in the United States, District of Columbia, and the Commonwealth of Puerto Rico will be affected. Devices sold before the standard compliance deadline are not affected.

Manufacturers' Efforts

In order to make the task of complying with the FDA standard manageable, some monitor manufacturers have been attempting to keep their apnea monitoring systems compliant with the latest versions of the standard. Some manufacturers also have a monitor trade-in program through which monitor purchasers can have systems updated to meet the standard when it becomes effective.

UMDNS Terms

  • Apnea Monitors [12-575]
  • Apnea Monitors, Recording [17-885]
  • Impedance Pneumograph Monitors [12-621]


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