Medical Devices Safety Update, Volume 4, Number 6, November 2016

1 November 2016

Medical Devices Safety Update is the medical device safety bulletin of the Therapeutic Goods Administration (TGA)

New insights into orthopaedic implants

An additional 107,740 hip, knee and shoulder joint replacement procedures have been included in this year's Australian Orthopaedic Association National Joint Replacement Registry annual reports, with shoulder procedures included in the main report for the first time.

The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) annual reports offer insight into the performance of orthopaedic implants being used in this country, providing the TGA with vital data to underpin its monitoring of orthopaedic implant safety.

Eight implants with higher-than-expected revision rates were newly identified in the 2016 annual reports published on 1 October, consisting of five hip and three knee prostheses. Two of the newly identified implants are no longer used. The sponsors of the remaining implants have been contacted by the TGA to provide further information.

All surgeons who have used particular implants are notified when the TGA undertakes regulatory action involving those implants, giving them the information they need to optimise patient care.

Among many other functions, the AOANJRR provides population-based data on the comparative outcome of individual prostheses used in Australia. The annual reports contain information about orthopaedic implants that are having higher-than-expected rates of revision. The main AOANJRR report is based on an analysis of 1,123,643 primary and revision joint replacement procedures (498,660 hips, 592,577 knees and 32,406 shoulders) performed before 31 December 2015. This represents a total of 107,740 additional procedures compared with the previous report. Shoulder procedures have been incorporated into the main annual report for the first time in 2016 (shoulders had previously been discussed in one of the AOANJRR’s many supplementary reports).

The reports compare the performance of individual implants with all implants of that type and identify those that do not appear to be performing as well as the others, using the revision rate as a measure. Joint replacement surgery is considered to be one of the most effective forms of surgical intervention and the overall revision rates are generally low, even for many of the implants for which the revision rate is considered to be higher-than-expected.

Expert advice

In reviewing whether the implants identified in the reports require regulatory intervention, the TGA will seek advice from the Orthopaedic Subcommittee (OSC) of the Advisory Committee on the Safety of Medical Devices. The OSC advises the TGA whether the reported revisions are of significant clinical concern. Based on this advice and other information, including that provided by the relevant sponsor, the TGA will then take regulatory action if required.

When regulatory intervention is necessary it is reported to all surgeons who have used the implants through a hazard alert and details of the action/intervention are published on the TGA website. The AOANJRR data regarding the eight newly identified implants, along with the sponsor responses, will be considered at the OSC's December meeting.

Elevated revision rates

Higher rates of revision are of concern because, as with any major surgery, orthopaedic surgery is associated with significant health risks. However, there are many reasons why a particular implant may be having a higher-than-expected rate of revision (including patient-related factors such as age and level of activity) and an elevated revision rate does not necessarily mean that the TGA needs to take regulatory action.

The AOANJRR annual reports list a total of 43 implants identified before 2016 that had higher-than-anticipated revision rates and were still being used during the reporting period. The TGA may choose to continue monitoring implants and not take regulatory action, even though the revision rate is higher-than-anticipated, for a variety of reasons including:

  • the implant had been used in a select patient population that is at a higher risk of revision
  • use of the implant offers unique benefits that compensate for the higher risk of revision
  • the implant is very new to the market, has been used in low numbers and other information indicates that the revision rate will decrease rapidly.

Identified and no longer used

There are 77 implant combinations in this category. In most cases (45) they were identified after the implant combination had been withdrawn from the market or was no longer used. In the other cases (32) the implants were withdrawn after TGA intervention.

Best practice model

All implants have a limited life in the human body and may need to be revised at some point in time. However, it is important to ensure that implants do not require replacement too often or too soon after implantation. The TGA works closely with the AOANJRR and where it is confirmed that the implant is the primary cause of early revisions, the TGA can require its removal from the market.

The AOANJRR and its close links to the TGA are regarded as an international best practice model of the use of post-market data to monitor device safety.

Standard improves heat pack safety

The TGA has collaborated with Standards Australia to improve the safety of microwaveable heat packs.

Microwavable heat packs with filling which has dried and aged, been overheated and/or not used correctly (for example, placed under bedding) have the potential to catch fire. This has resulted in deaths, accidents, burns and loss of property.

The TGA has worked with Standards Australia in the development of an Australian Standard: 'Microwavable heat packs - Wheat and other organic filling materials' (AS/NZS 5116:2016). This Standard informs manufacturers of microwavable heat packs of product labelling requirements (including safety warnings) as well as instructions for testing the packs for overheating.

The aim of the Standard is to provide manufacturers of microwavable heat packs with validated testing methods to ensure their product is sufficiently resistant to overheating. Products that are manufactured using this standard will provide users with sufficient information on how to use the product safely.

The Standard applies to microwavable heat packs including wearable products, bags, pillows, and children's products. It covers products containing organic materials including wheat, rice, legumes, pulses, dried flowers, herbs and other grains, but does not cover packs containing chemicals, crystals or gels.

The TGA was involved in validating the tests detailed in the Standard. Initially the aim of the tests was to minimise the risk of fires associated with overheating of the contents. The final published Standard includes a requirement that - when heated in accordance with the manufacturer's instructions - the pack temperature shall not exceed 70 degrees celsius. This requirement should reduce the risk of serious burns as well as fires.

This Standard has now been published on the Standards Australia website.

Practice points: Postoperative monitoring

Understanding the time periods of highest risk and individual patient risk factors for respiratory depression may assist in efficient resource allocation in postoperative patients.

Drug-induced respiratory depression is associated with significant morbidity and mortality in the postoperative period and medical devices such as telemetry systems are a valuable resource often used for monitoring patients after surgery.[1]

Continuous electronic monitoring of oxygenation and/or ventilation may allow for more rapid diagnosis and prevention of drug-induced postoperative respiratory depression.[1] Given recent calls for vigilance regarding opioid-induced postoperative respiratory depression,[2] telemetry devices may be subject to increasing demand. Understanding the time periods of highest risk, and individual patient risk factors for respiratory depression may assist in efficient resource allocation.

Weingarten et al suggest that the first 24 hours postoperatively are the highest risk time for respiratory depression, with most events occurring in the first 12 hours.[2] This may be the most critical time for the use of telemetry systems.

Patient factors that increase risk for postoperative drug-induced respiratory depression include obesity, sleep apnoea, increasing age, organ system dysfunction, concurrent CNS depressant use and preoperative chronic opioid tolerance.[1]

Patients with these risk factors may also benefit from telemetry monitoring outside of the 24-hour window, but, particularly during high-risk periods.

Staff surveillance vital

Staff surveillance is equally, if not more important than telemetry systems in the monitoring of postoperative patients. Telemetry devices should be used to complement rather than replace staff surveillance. Sole reliance on telemetry devices in the postoperative setting could result in inadequate monitoring, which could lead to catastrophic consequences for patients such as brain injury or death.[3]

At 1 October 2016 the TGA had received 51 reports of adverse events related to the use of telemetry devices. In many of these reports, the device failed to alarm when the monitored patient experienced a serious arrhythmia. The following hypothetical example highlights the importance of combining staff monitoring with the use of telemetry devices:

  • a patient is undergoing monitoring with a telemetry system
  • the patient collapses with the telemetry device connected
  • the telemetry system displays ventricular tachycardia, but the system does NOT alarm
  • the collapse is witnessed by a nurse
  • because the event was witnessed, an appropriate clinical response could be initiated.

In this situation, it was staff monitoring, not the telemetry device that prompted the clinical response.

Such reports highlight the importance of using these devices appropriately in accordance with the Instructions for Use (IFU), and in combination with staff surveillance. This situation could have been catastrophic if staff were relying solely on the device alarming.

Key points:

  • Telemetry devices must be used in combination with staff surveillance.
  • Telemetry devices are a limited resource, and should be allocated according to risk. In the postoperative setting, the period of highest risk of respiratory emergencies, often related to opioid use, is the first 24 hours after surgery.
  • Appropriate use of telemetry devices according to the IFU is crucial
  • All adverse events and near misses should be reported to the TGA via the Incident Reporting and Investigation Scheme (IRIS).

References:

  1. Weinger MB, Lee LA. No patient shall be harmed by opioid-induced respiratory depression; proceedings of essential monitoring strategies to detect clinically significant drug-induced respiratory depression in the postoperative period conference. APSF Newsletter. 2011 Fall; 26:21-40.
  2. Weingarten TN, Warner LL, Sprung J. Timing of postoperative respiratory emergencies: when do they really occur? Curr Opin Anaesthesiol. 2016 Sep 28. [Epub ahead of print]
  3. Top 10 health technology hazards for 2016. Health Devices 2015, Nov. Emergency Care Research Institute. [Log-in required]

Recent safety alerts

Below are TGA safety alerts relating to medical devices published since the last edition of Medical Devices Safety Update.

St Jude ICDs and CRT-Ds - various models: Hazard alert - risk of premature battery depletion

Animas Vibe insulin pumps: Safety advisory - potential battery issues if compartment cracked

Invacare Birdie Lifter series of hoists: Recall for product correction - risk of injury due to D-clip becoming damaged

LFIT Anatomic CoCr V40 femoral heads (used in hip replacements): Hazard alert - risk of adverse events due to potential taper lock failures

Breast implants: Update on TGA monitoring of anaplastic large cell lymphoma

Rehab Assist C-Series ceiling hoists: Recall for product correction - potential for attachment swivel to break

Accu-Chek Connect Diabetes Management app: Safety advisory - update app to correct programming error

Tandem Bipolar Hip System: Hazard alert - potential need for revision surgery due to parts becoming detached

GlucaGen HypoKit: Recall - risk of needles becoming detached from syringes

Comfort impregnated cloth topical skin products: Recall - potential for bacterial contamination

HeartWare Ventricular Assist Device: Hazard alert – potential for electrical fault

What to report? Please report adverse events, as well as near misses

The TGA encourages the reporting of any suspected adverse event or potential adverse event relating to a medical device. Adverse events can involve actual harm to a patient or caregiver, or a near miss that may have resulted in harm.

Some issues relating to medical devices that may lead to adverse events and prompt you to report include:

  • mechanical or material failure
  • design issues
  • labelling, packaging or manufacturing deficiencies
  • software deficiencies
  • device interactions
  • user/systemic errors.

Suspected adverse events or near misses can be reported directly to the TGA:

For more information about reporting, visit www.tga.gov.au or contact the TGA's Medical Devices Branch on 1800 809 361.

Disclaimer

The Medical Devices Safety Update (MDSU) is aimed at health professionals and is intended to provide practical information on medical device safety, including emerging safety issues. The information in the MDSU is necessarily general and is not intended to be a substitute for a health professional's judgment in each case, taking into account the individual circumstances of their patients. Reasonable care has been taken to ensure that the information is accurate and complete at the time of publication. The Therapeutic Goods Administration gives no warranty that the information in this document is accurate or complete, and does not accept liability for any injury, loss or damage whatsoever, due to negligence or otherwise, arising from the use of or reliance on the information provided in this document.

© Commonwealth of Australia 2016

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For correspondence or further information about Medical Devices Safety Update, contact the TGA's Medical Devices Branch at iris@tga.gov.au or 1800 809 361.


Medical Devices Safety Update is written by staff from the Medical Devices Branch.

Editor: Ms Pamela Carter

Deputy Editor: Mr Aaron Hall

TGA Principal Medical Adviser: Dr Tim Greenaway

Contributors include: Dr Jorge Garcia, Dr Alison Stubbs, Mrs Anne Howatt