Pool Safety Council Laboratory 2734 Land O'Lakes Boulevard Land O'Lakes, Florida Sincerely,

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1 July 9, 2010 Pool Safety Council Laboratory 2734 Land O'Lakes Boulevard Land O'Lakes, Florida RE: SVRS Technology Dear Mr. Pennington, Thank you for inviting me to the Pool Safety Council Laboratory on July 6, 2010 to see first-hand the SVRS technology. Based on my observations (of about eight trials) that were conducted for me, I can see the benefit of SVRS s ability to eliminate/minimize the pressure differential issues that cause limb (for the demonstration, a plastic bat and composite block) entrapment in an intake pipe. The relatively quick response (on the order of 0.5 to 4.0 seconds based on the eight trials I observed of the Vac-Alert SVRS) should prove to be beneficial in preventing prolonged limb entrapment. Your demontrations of SVRS technology were encouraging, and I am hopeful that your pursuit of this technology and continual improvements will help save lives in the future. Sincerely, Steven M. Jachec, Ph.D., P.E. Assistant Professor of Ocean Engineering

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12 I College of Engineering Department of Marine and Environmental Systems Science Engineering Management September 13, 2010 Pool Safety Council Laboratory 2734 Land O'Lakes Boulevard Land O'Lakes, Florida RE: Evisceration timescale compared to SVRS time Dear Mr. Pennington, Thank you for giving me the opportunity to estimate the timescale for evisceration to occur. Data acquired from the Pool Safety Council (PSC) laboratory helped make this estimation possible. Using published literature and data from various sources (see SATOP #3464 report for details), I estimate the time for evisceration to be 1.86 seconds. Furthermore, based on data from PSC, I can compute the time for SVRS technology to eliminate the vacuum, 1.23 seconds. Utilizing this one set of trial data (50 ft pipe with a diameter of 2 inches of Schedule 40 PVC, 3 HP pump operating 36 inches above the sump producing 70 GPM, with and without SVRS) and computational method discussed in the above report, the SVRS was able to break the vacuum in a shorter amount of time than for evisceration to occur. This is an encouraging result, which suggests SVRS may be suitable technology to minimize or prevent this type of injury from occurring. However, it is still a challenging problem with many physical and anatomical nuances that need to be addressed, better understood, and quantified. I recommend more trials be conducted, the topic be further pursued, and conclusions shared with the pool/spa community. If possible, results should be published in well-respected, peer-reviewed journals to demonstrate the rigor involved in potential experiments and calculations. Sincerely, Steven M. Jachec, Ph.D., P.E. Assistant Professor of Ocean Engineering Florida Institute of Technology High Techwith a Human Touch t50 West University Boulevard, Melbourne, FL (321) Fax: (321) dmes@fit.edu 'f:..~,nvllio S,.- ~ ~~~ ~ :z ~ E"~~S J'YSTl\\\~ Our mission is to integrate oceanography, ocean engineering, environmental science, meteorology and related academic concentrations into interdisciplinary knowiedge-based optimal solutions to vital contemporary issues through education, research and service.

13 Technical Report Summary of: RTA # 3464 Estimating transanal evisceration timescales FINAL REPORT Prepared by: Steven M. Jachec, Ph.D., P.E. Department of Marine and Environmental Systems Florida Institute of Technology 150 W. University Blvd. Melbourne, FL Phone: Fax: sjachec@fit.edu Through: Space Alliance Technology Outreach Program (SATOP) - Florida Technological Research and Development Authority (TRDA) 1050 W. NASA Blvd., Suite 125 Melbourne, FL Phone: x111 Fax: September 2, 2010

14 Abstract Injury and death of children due to transanal eviscertation by sitting on uncovered pool suction drains has been documented. Two factors, pressure and pressure-duration, are responsible for causing the injuries and/or deaths. Survival depends on quick response which leads to minimal intestinal prolapse and/or evisceration. Therefore, a timescale estimate for this process to occur is pursued using a combination of analytical methods, laboratory data, and critical threshold limits. This is a complex and unique process that depends on several anatomical and flow physics factors. The timescale estimate presented here is partitioned into two pieces: a static time estimate is made, which represents the time needed for intestinal avulsion to occur, and a dynamic time, which estimates the time it takes for the intestines to aspire once avulsion has occurred. The sum of the static and dynamic times leads to a total evisceration timescale of 1.86 s. ii

15 Contents 1 Purpose and objectives 1 2 Methodology and results Static assessment Dynamic assessment Synthesis and conclusions 7 iii

16 List of Figures 1 Time-series of pressure from laboratory experiment, which shows the classic signature of a water hammer Closeup of pressure signal at onset of blockage (red star) and critical pressure threshold (black line) Integrated pressure. Black line shows threshold value of pressureduration to induce evisceration Closeup of integrated pressure. The red patch shows the integration build up towards reaching the critical -5.4 psi-s value of pressure duration. The associated time on the time line where this threshold is reached is 5.56 s; the original blockage occurs at 5.12 s. This difference yields 0.44 s iv

17 1 Purpose and objectives Sitting on uncovered pool suction drains can cause rectal prolapse with sigmoid laceration and subsequent small intestine evisceration. Juern et al. (2010). Over the course of several years, injuries and (ultimately) deaths have occurred to children experiencing such traumatic events. Cain et al. (1983); Hultman and Morgan (1994); Juern et al. (2010) provide summaries of published cases. Survival rates vary and those who have survived lead a less than normal quality of life. From the literature, there does seem to be a correlation between survival and length of intestinal prolapse. It seems that the less bowel resection that is needed, the better the chance of survival and a chance at a higher quality of life. Associated with the length of intestinal prolapse is the time exposure over which the pressure difference is applied between the body cavity and the pool suction drain. Therefore, the amount of time it takes for prolapse and complete evisceration to occur is a concern. The purpose of this work is to estimate the time it takes for transanal evisceration to occur based on analytical methods and lab data. 2 Methodology and results The time it takes transanal evisceration to occur due to suction experienced at pool drains is estimated. This is a complex process that involves an individual s anatomy and digestion, suction pressure, length of exposure, and pressure seal. A simplified approach is presented that attempts to model the timescale using a combination of analytical methods, experimental lab data, and existing threshold danger limits. A cornerstone idea towards understanding this process and estimating the time is how much pressure difference the body can withstand and over what duration. It has been determined that danger limits exist in terms of pressure and pressure-duration, which are 2.2 psi and 5.4 psi-s (using animals as test subjects), respectively ( The plan is to partition the evisceration process into two stages, a static one in which the body can with- 1

18 stand pressure differences before avulsion occurs, and a dynamic one in which avulsion has occurred and the intestines are exiting the anus. The sum of the time for the static part (t s ) and the time for the dynamic part (t d ) provides a total time (t) estimate: t = t s + t d. (1) 2.1 Static assessment The lower gastrointestinal system is connected within the body cavity with various ligaments, muscles, and membranes. They vary in strength, but weak points of the bowel are the ligament of Treitz and the ileocecal valve for evisceration cases (Juern et al. 2010). Towards understanding the timescales involved, experimental pressure data subject to complete blockage are collected by the Pool Safety Council. The blockage is meant to choke off the flow and represent what happens when a child sits on a pool suction intake drain. Figure 1 shows pressure (p) results of this experiment using a 3 HP pump flowing at 70 GPM through a 50 ft length of 2 in PVC suction pipe; the black horizontal line represents the critical threshold limit of -2.2 psi (2.2 psi suction pressure). Constant normal (i.e., unblocked) pressure is experienced at the beginning of the experiment of roughly 0.32 psi. At 5.12 s, the constant blockage is created, denoted with a red star in the plot, which generates a sharp decrease in pressure that reaches a maximum suction pressure of psi in 0.76 s. Moreover, it takes about s to reach the critical -2.2 psi threshold; Figure 2 shows a closeup of suction. This sudden and constant blockage causes a positive pressure wave to occur that travels up the pipe at the speed of sound and results in the oscillations observed in this figure. This is known as a water hammer (Crowe et al. 2005). The magnitude of the pressure wave oscillations decrease nonlinearly until viscous effects of the water and inner perimeter pipe friction dampen the pressure signal. At 30 s it has reached a nearly steady-state of (suction) pressure of about psi. In addition to the pressure, the pressure-duration is computed as it is another viewpoint of evisceration. The -2.2 psi is the threshold in which injury begins 2

19 Figure 1: Time-series of pressure from laboratory experiment, which shows the classic signature of a water hammer. to occur, but pressure-duration, the amount of time the lower gastrointestinal system experiences a given pressure, helps guide when evisceration will occur. From it has been determined that -5.4 psi-s (suction pressure duration of 5.4 psi-s) is the critical threshold value. Pressureduration (D) is computed as the time integration of the pressure (p): D = tend t start p dt, (2) where t start is the time associated with the blockage and t end is a time much later in the time-series after the blockage has occurred. Given the pressure data in 3

20 Figure 2: Closeup of pressure signal at onset of blockage (red star) and critical pressure threshold (black line). Figure 1, numerical quadrature can be applied through a trapazoidal rule for integration. Applying this numerical scheme results in a plot of pressure-duration (Figure 3). The plot (and integrations) begins at the time when blockage occurs and extends to the length of the experiment, 30 s. The black line represents the -5.4 psi-s threshold and the pink star on the plot shows this critical value is achieved at 5.56 s, which is seen in Figure 4. The red patch in Figure 4 illustrates the integration up to the -5.4 psi-s threshold, and the associated point on the time line where the threshold is reached is 5.56 s. Since the blockage occurs at 5.12 s, it takes 0.44 s for this critical value to be reached from the blockage onset, or t s = 0.44 s. 4

21 Black line shows threshold value of pressure- Figure 3: Integrated pressure. duration to induce evisceration. 2.2 Dynamic assessment The goal here is compute the dynamic time using a combination of the flow out of the anus and volume to be aspired. The second stage of this process assumes that complete intestinal avulsion has occurred; therefore, no frictional considerations are made. A dynamic time estimate is computed based on an energy equation with an exit loss coefficient (K L ) of 1.0 as p γ = V 2 2g + K V 2 L 2g, (3) 5

22 Figure 4: Closeup of integrated pressure. The red patch shows the integration build up towards reaching the critical -5.4 psi-s value of pressure duration. The associated time on the time line where this threshold is reached is 5.56 s; the original blockage occurs at 5.12 s. This difference yields 0.44 s. which can be re-arrange to solve for the velocity (V ) exiting the anus V = g p γ, (4) where p is the greatest suction (negative) pressure difference of psi (see Figure 1), γ is the specific weight of the fluid (water is chosen) within the bowels that is 0.04 lb in 3, and g is the acceleration due to gravity taken as 386 in s 2. This results in a velocity of 32 ft s 1. Assuming that the anus has a diameter of 6

23 1 in for a 5-6 year old child, leads to a flow (Q) out of the anus of ft 3 s 1. Furthermore, assuming 0.25 ft 3 volume ( ) of bowel and associated anatomy to be aspired for a 5-6 year old child at a flow rate of ft 3 s 1 allows the dynamic time to be estimated using t d = Q, (5) that results in a dynamic time of 1.42 s; t d =1.42 s. This time may be on the short side as it assumes complete avulsion, a constant psi suction pressure, and no frictional effects taken into account. All are likely not the case; all would increase the dynamic time. 3 Synthesis and conclusions Based on the above calculations, the total time estimate for evisceration is summation of the static (t s ) and the dynamic (t d ) times: t = t s + t d = 0.44 s s = 1.86 s. (6) The total time estimate for evisceration to occur is 1.86 s. Evisceration is a complex process and every case is unique. Using the best available data, simplified analytical methods, and existing critical (nonhuman) threshold limits, this estimate has been computed. Better/more data and more sophisticated methods should be pursued, which would refine this estimate. References Cain, W. S., C. G. Howell, M. M. Ziegler, A. J. Finley, M. J. Asch, and J. P. Grant, 1983: Rectosigmoid perforation and intestinal evisceration from transanal suction. Journal of Pediatric Surgery, 18. 7

24 Crowe, C. T., D. F. Elger, and J. A. Roberson, 2005: Engineering Fluid Mechanics. John Wiley & Sons, Inc., eighth edition. Hultman, C. S. and R. Morgan, 1994: Transanal intestinal evisceration following suction from an uncovered swimming pool drain: case report. The Journal of Trauma, 37, Juern, J., D. Schmeling, and B. Feltis, 2010: Transanal wading pool suction-drain injury resulting in complete evisceration of the small intestine: case report and review of literature. Journal of Pediatric Surgery, 45, E1 E3. 8

25 Contact: PSC Media Phone: (877) FOR IMMEDIATE RELEASE NASA Funds Research on Limb Entrapment and Evisceration New research supports pool safety technologies (SVRS) beneficial in preventing limb and evisceration entrapment. WASHINGTON, D.C. August 18, 2010 New research funded by NASA through the Space Alliance Technology Outreach Program (SATOP) verifies the suction forces involved with limb entrapments and that the release of vacuum can free the limb. In a separate report, the estimated number of seconds from start to finish in which eviscerations occur was also discovered. SATOP s Florida center, the Technological Research and Development Authority (TRDA) and the Pool Safety Council (PSC), in conjunction with Florida Institute of Technology conducted a series of tests to confirm these groundbreaking results. In the first of two reports issued by Steven M. Jachec, Ph.D., P.E., of the Florida Institute of Technology, it was determined that the entrapping force on an open pipe is significant due to the suction of the pump, which is amplified when a child s arm becomes entrapped, creating additional friction from the arm itself and the inside of the pipe. In a memo regarding his results, Dr. Jachec confirms that SVRS technology is beneficial in eliminating/minimizing the pressure differential issues that cause a limb to become sucked in and entrapped by an intake pipe. The findings further verify that in the event of limb entrapment, the SVRS devices quick release time (between 0.5 and 4.0 seconds) prevents prolonged limb entrapment. With the release of the vacuum on the pipe, the arm can be freed from both the suction and friction forces. We have long believed that an SVRS would prevent limb entrapments because of reports that show a child s arm is released when a pool pump is shut off said Paul Pennington, Chairman of the Pool Safety Council. This report finally confirms what we ve been saying all along, unfortunately it is too late to save some of these lives, but still soon enough to prevent more injuries and fatalities from happening. In a second report, Dr. Jachec was able to determine the total start to finish time estimate in which an evisceration would occur. According to his report, it is estimated that it takes 1.86 seconds before an evisceration could happen. Pennington added that by finally knowing how long it takes before an evisceration will occur, we can now see that SVRS technology, which is designed to release the vacuum from a pool drain in less than half a second, can mitigate, if not prevent eviscerations all together. According to Pennington, There are five types of entrapment: body, limb, evisceration, hair, and mechanical. In order to comply with pool safety standards, compliant drain covers as well as antientrapment devices must be installed in pools and spas, providing layers of entrapment protection.

26 ASME/ANSI A approved drain covers and back up devices work together to prevent all 5 types of entrapment hazards. SATOP is a cooperative program made up of an alliance of more than 45 private corporations, universities, colleges and NASA centers in Florida, New Mexico, New York, and Texas who assist in providing technological assistance to small businesses and organizations. The Pool Safety Council (PSC) is a Washington, DC-based swimming safety and drowning prevention advocacy group. Members of PSC include Professional Engineers, pool industry professionals, child safety advocates, and concerned parents. The PSC partners with prominent safety groups and testing agencies such as SafeKids USA, Drowning Prevention Foundation, and most recently NASA. The PSC is dedicated to providing information, education, and training to prevent drowning nationwide. It provides comprehensive safety materials and training to pool operators, including guidance on the Pool and Spa Safety Act requirements. For more information please visit

27 Could you tell me a little bit about the Pool Safety Council lab? What are the facilities like? When was it established? What is the objective? The PSC lab is an offshoot of the ASTM atmospheric vent committee. In 2004 extensive ASTM testing was conducted in the Tampa, Florida area. The lab has continued to evolve to accommodate more and more complex tests, and eventually developed the property described below into the PSC lab. We continually add more and more testing capabilities to our lab. The PSC test lab sits on three acres of usable area, consisting of 2,000 square feet of indoor, air conditioned space with a computer data acquisition and monitoring station, pressure and vacuum transducers that are capable of 100 readings per second, flow meters, pressure and vacuum gauges, monometer stations, and temperature monitors and recorders. The test lab also includes a 3,000 square foot area with an outdoor test tank which features interchangeable piping for hydraulic testing, with 25 foot, 50 foot, and 100 foot piping distances from suction outlets to pool equipment. The test facility also features in-ground swimming pool and spa systems for conducting additional real-world testing and training. We have gone to great lengths and expense to ensure we have a state of the art facility for a wide variety of testing scenarios. I understand PSC has been approved for non-profit safety resarch using NASA assets. How does one qualify? NASA funds TDRA (Technological Development and Research Authority), which founded and administers SATOP (Space Alliance Technology Outreach Program). SATOP is a cooperative program made up of an alliance of more than 45 private corporations, universities, colleges, and NASA centers in Florida, New Mexico, New York, and Texas who assist in providing technological assistance to organizations. SATOP assists organizations with technology research and development, and accepted PSC s requests to aid with research regarding limb and evisceration entrapments. SATOP then funded Dr. Steven Jachec, Ph.D., P.E. from Florida Tech to conduct this research. This is a natural relationship because a pool pump suction creates vacuum conditions approaching those found in outer space. They are the leading experts on fluid dynamics, space and space suits, which is related to conditions of entrapment. Using a collaborative relationship with NASA, the PSC lab and many of our Professional Engineer members have been able to do more in depth studies, validating and supporting our conclusions. What was the objective of these particular studies? The objective of these studies was to get closer to understating the factors that play a role in limb and evisceration entrapments. These studies show that vacuum release or vacuum limiting can mitigate or even possibly eliminate limb and evisceration entrapments. What do you believe these results say about the role of safety vacuum release systems and automatic pump shut-offs in protecting against evisceration? In protecting against limb entrapment? The significance of these studies are two-fold. The studies have shown that when a child s arm goes into a 2 pipe, that there is an immediate force. The further the child s arm goes in, the stronger the force becomes, and can actually increase, depending on the size of the child s arm and how far in the pipe it goes. The interesting thing, in which we ll be doing further studies with other organizations (such as National Science Foundation NSF), such as at what point does a vacuum release system relieve the vacuum? This study suggests the theory, which will be researched in greater detail, that a vacuum release system could actually become in a suction limb entrapment scenario a suction limiting system, because the trigger may be sensed by a vacuum release system before there is a seal and a full limb entrapment occurs. We know that when a child s arm is stuck because of suction related

28 forces in a suction pipe, and the power to the pump is shut off or the vacuum is released, the child s arm comes right out of the pipe. Regarding eviscerations, we have learned that there are many variables, such as, has the child recently eaten, the bathing suit, and how the child sits on the suction outlet. We know that in two cases, when the parents turned off the pump to free their child from the suction outlet, there was 8 of intestines pulled out, which is medically repairable, and yet others, the child is completely disemboweled. This study shows that in the most conservative case, this full disembowelment takes approximately 1.86 seconds. A vacuum release or a vacuum limiting system, depending upon pump to sump distance, may relieve the dangerous suction force before full disembowelment occurs. This could be the difference between life and death for the victim. Dr. Jachec did extensive reviews of the American Medical Journals for peer reviewed reports, and had conversations with the medical community that handled past and recent evisceration cases. What other implications would you say these results have? These research results are the seed to start the process for more studies and hopefully more people becoming involved in this new research and analysis. This is important so that we can more thoroughly understand these types of injuries. We hope this will help kick-start new studies and new thinking about the complex issues of limb and evisceration entrapments, so that we ll have a better way to protect bathers from these injuries. This is not the end, but the start of new research. What does Pool Safety Council plan to do with this data? We will use this data to qualify for government funding and further and deeper research. What future testing/studies does Pool Safety Council have planned? See above. PSC has for some time been researching how to properly build dual or split drains and the complex relationship between the open area of a suction outlet cover, the interconnector pipe diameter between two suction outlets, and the importance of port size and sump orientation to minimize elbows and fittings. PSC testing systems are currently capable of measuring 32 different pressure or hydrostatic readings to characterize the fluid dynamics throughout a dual drain system. We will also be doing further testing and research utilizing extensively 3 rd party (i.e. NASA, NSF) organizations to investigate how to prevent entrapments before they happen. This would include proper construction of dual or split drains, gravity systems, hydrostatically balanced atmospheric vent systems, and atmospheric vents in conjunction with skimmers, for both existing and newly constructed pools and spas.