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Appendix E The Regulatory History of Cerebrospinal Fluid Shunts for Hydrocephalus
Appendix E The Regulatory History of Cerebrospinal Fluid Shunts for Hydrocephalus
Pages 347-381
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has regulatory authority over these and all medical devices. Historically the FDA has taken a limited regulatory approach toward CSF shunts.
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348 SAFE MEDICAL DEVICES FOR CHILDREN tricles. The largest of the ventricles are the two lateral ventricles, which occur in parallel and have a shape that is complex but that can be broadly described as the appearance of a medially angulated letter C with a tail extending from their back (Figure E.1)
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APPENDIX E 349 FIGURE E.2 The cerebrospinal fluid system (4)
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350 SAFE MEDICAL DEVICES FOR CHILDREN fluid produced and reabsorbed. Some of these pathologic processes are congenital (e.g., congenital obliteration or stenosis of aqueducts or obliteration of the resorbtive capacity of the arachnoid granulations)
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In infants, this manifests as head growth that exceeds the normal rate, bulging of the normally flat anterior fontanelle (soft spot) of the skull, and behavioral signs, including irritability and unexplained vomiting.
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The natural history of untreated hydrocephalus is ominous. While some patients are able to arrive at an equilibrium in which excess CSF volume is compensated by head growth and brain volume reduction to result in normal intracranial pressure, most are not.
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APPENDIX E 353 FIGURE E.3 CT scans of a child with hydrocephalus and a child with transependymal flow at the tips of the lateral ventricles. (Courtesy of Jeffrey P
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354 SAFE MEDICAL DEVICES FOR CHILDREN FIGURE E.4 MRIs of a child with hydrocephalus. (Courtesy of Jeffrey P
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APPENDIX E 355 surgical treatment once the diagnosis is established. Occasionally these medications can be used to temporize until surgical therapy is undertaken, but there is no significant role for medical therapy in the long-term, contemporary treatment of hydrocephalus.
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With time and experience, a number of complications related to the placement of CSF shunt catheters within the vascular system were identified. When such catheters stopped working, the revision operation could be quite challenging (7)
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APPENDIX E 357 the need for elective lengthening of the atrial catheter was reported in 1976 (9)
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358 SAFE MEDICAL DEVICES FOR CHILDREN tion or fracture of tubing) , migration of the system (often, but not always, associated with disconnection or fracture)
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APPENDIX E 359 word-of-mouth dissemination of the knowledge of bowel perforation complications, the distal spring valve fell quickly out of use. Advances in the understanding of CSF physiology fostered technologic advances in valve design in the 1980s and early 1990s.
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APPENDIX E 361 20 shunt nephritis 18 infection 16 14 12 Publications 10 of 8 Number 6 4 2 0 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Year of Publication FIGURE E.6 Shunt infection publications by year. gradual increase in the number of peritoneal shunts represents a successful hallmark in the history of CSF shunts.
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362 SAFE MEDICAL DEVICES FOR CHILDREN damage. The spread of a brain tumor outside of the central nervous system through a shunt can seriously complicate the treatment of the tumor.
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APPENDIX E 363 TABLE E.1 Articles on Shunt Complications by Type of Complication Complication Articles # % Malfunction 179 14.1 Occlusion 59 4.6 Disconnection 16 1.3 Migration 29 2.3 Organ perforation 75 5.9 Infection 388 30.5 Infection 293 23.0 Abdominal: cyst or peritonitis 7 0.6 Shunt nephritis 88 6.9 Abdominal Cyst (no infection) 43 3.4 Hemorrhage 55 4.3 Abdominal metastasis 54 4.3 Pneumocephalus 28 2.3 Slit ventricles 33 2.6 Cardio-pulmonary 68 5.3 Mortality 12 0.9 Miscellaneous 412 32.4 Total 1,272 The relative frequency of publication of types of complication by year is shown in Figure E.7.
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THE PERIOD OF REGULATION Regulation Prior to Marketing In 1976, amendments to the Federal Food, Drug, and Cosmetic Act gave the FDA its first real authority to regulate medical devices. Devices were placed in three classes.
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The introduction to the subsequent report indicates that the decision to classify shunts as Class II medical devices was "based upon the belief that standards could be written to assure the safety and effectiveness of marketed shunts, and that clinical experience had proven shunts to be reasonably safe and effective" (64)
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database AN Approved Evaluation of Automatic Class III Designation ST Substantially Equivalent Subject to Tracking Regulations PT Substantially Equivalent Subject to Tracking and Postmarket Surveillance SF Substantially Equivalent Waiting on Future Policies SS Substantially Equivalent Special Labeling SE Substantially Equivalent SA Substantially Equivalent Awaiting Device Approval SW Substantially Equivalent Awaiting Drug Approval CS Substantially Equivalent CLIA Submission SK Substantially Equivalent Kit KD Substantially Equivalent Kit with Drugs SI Substantially Equivalent Market after Inspection SP Substantially Equivalent Postmarket Surveillance PR Substantially Equivalent Proposed Recision SU Substantially Equivalent with Limitations SN Substantially Equivalent for Some Indications SD Substantially Equivalent with Drug Determination of Non-Substantial Equivalence listed in FDA decision codes FB Subject to 515(b) Requires PMA NE Not Substantially Equivalent SC Not Substantially Equivalent Cannot Market SL Not Substantially Equivalent Improper Label RE Rescind Substantial Equivalence UD Unable to Determine Equivalence UO Unable to Determine Equivalence Outstanding Drug Issue UR Not Substantially Equivalent Unreliable Data OD Unable to Determine Equivalence Outstanding Device Issue SOURCE: (65)
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One must ask if this is a reasonable conclusion or if this conclusion is based on short-term effectiveness without sufficient consideration of long-term effectiveness and complications. Postmarketing Surveillance In 1999, the FDA convened the previously mentioned STAMP conference, "Shunt Technology: Challenges and Emerging Directions." The conference reviewed "families of closely related medical devices having broad use and most often, several years of marketing experience, as well as, a significant potential for adverse events." In presentations, patient advocates, industry representatives, and physicians familiar with cerebrospinal fluid shunts and the associated complications stressed continuing difficulty with problems of shunt function and infection.
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The existing system for monitoring these devices for problems should be examined for effectiveness both in identifying problems and in prompting corrective action. The 1976 Medical Device Amendments granted FDA authority to issue regulations requiring adverse event reporting for marketed medical devices.
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, a not-forprofit health services research agency, maintains a version of the MDR and MAUDE databases with additional search capabilities. Both versions of the databases were used for this report.
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370 SAFE MEDICAL DEVICES FOR CHILDREN TABLE E.3 Search Strategy (MDR Reports) for Adverse Events for CSF Shunts Step Items Description (use 4 digit years)
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APPENDIX E 371 TABLE E.4 CSF Shunt Reports in the MAUDE Database Misclassified as a Non-Shunt Device Listed FDA Product Code Actual Product Report # |
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This analysis of the reporting of shunt-related death suggests that both the outcome section of the reports and the automated text search of the entire narrative file result in overlapping and incomplete ascertainment of specific problems. Because there were simply too many reports for individual review, and accepting the likely inaccuracies suggested by the detailed review of reporting of "DEATH," the computerized text searching of the MDR and MAUDE databases using the strategies described above was used to classify the reported complications using the classification scheme presented in Part 2.
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No alerts were identified. ECRI defines action items as "reports of medical device problems, hazards, and recalls that have been verified by ECRI with the device manufacturer/distributor.
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to the shunt subset of the MAUDE database. Shunt complications in the database were identified by searching the text of the narrative descriptions of adverse events in the database (the details are given in Appendix D of the main report)
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A subsequent study identified 26 cases of meningitis in 4,264 children with cochlear implants. This represents a substantial increase over the expected rate of meningitis, but is far below the rate of 7 to 9 percent for CSF infections as seen with CSF shunts (74)
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As of June 2003, there were 171 CSF shunt-related premarket notifications in the FDA database, resulting in decisions affirming "substantial equivalence." These decisions have allowed manufacturers to introduce many variations and modifications of the CSF shunt and its parts. For an important medical device with a relatively small market, the 510(k)
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The current structure of the adverse event reporting system makes it difficult to search it for the details necessary to analyze specific complications. Frequently, the data necessary to classify the adverse event report in a clinically useful manner is simply not present.
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378 SAFE MEDICAL DEVICES FOR CHILDREN have failed to reduce rates of obstruction. This failure has heightened collective awareness concerning our incomplete understanding of CSF physiology and the pathophysiology of hydrocephalus.
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Predictors of death in pediatric patients requiring cerebrospinal fluid shunts. J Neurosurg Spine 2004;100(5)
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Cerebrospinal fluid shunt infection: a prospective study of risk factors. J Neurosurg 2001;94(2)
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Postoperative infection in cochlear implant patients. Otolaryngol Head Neck Surg 2004 July;131(1)
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