Reptile Face Masks Preliminary Design Report October 19, 2005 Team Members: Katy Reed – Team Leader Kristen Seashore – Communicator Steve Skroch – BWIG Janelle Anderson – BSAC Clients: Kurt Sladky, DVM Professor – School of Veterinary Medicine Steve Johnson, MD Professor – School of Veterinary Medicine Advisor: Professor Walter BlockAbstract: The objective of this project is to construct four airtight masks for a Corn Snake and Bearded Dragon that can be attached to a pneumotachometer so the affects of opiates on reptile respiration can be measured. The masks should be non-invasive and comfortable for the test subjects while being easy to use and clean by the researchers. These masks will help our client collect respiratory data for a study analyzing the effects of opioids on reptile pain response and breathing. Background: Problem Statement Dr. Kurt Sladky and Dr. Steve Johnson are investigating the effects of opioids on reptile respiration and pain response latency. Our clients have already collected relevant data for aquatic turtles, but they lack a device to collect pneumotachometric data from terrestrial reptiles. Two devices for a Corn Snake (Figure 1) and two devices for a Bearded Dragon (Figure 2) are required. Problem Overview Two devices for each reptile species used are needed. The Corn Snake device must have an air-tight fit with the reptile’s skin. Each device must have two ports, one for incoming air regulated at a constant pressure, and the other for outgoing air that leads to the pneumotachometer. The devices must be easy to use and easy to clean with common disinfecting detergents. Also, the devices must not harm the reptiles. Figure 2: A Bearded Dragon [6] Figure 1: A Corn snake [6] Problem Motivation Very little research has been done on the effects of opioids on reptiles. There are no standard designs for reptilian pneumotachometric experiments currently on the market, making investigation of the effects of opioids on reptile respiration extremely difficult at this time. Research on anesthetics such as opioids is important because the proper dosage of anesthetics for reptiles during surgery is currently unknown. Over-anesthetizing the reptile may kill it while under-anesthetizing it might not suppress its pain. This research will allow us to determine the appropriate amount and type of opioids to use on the reptile to be effective without causing any harm.Design Constraints There must be four separate airtight devices, two each for Corn Snakes and Bearded Dragons. The devices must be large enough to hold the reptile’s head with a minimal amount of dead or unused space in the chamber. The snake has a neck ~ 10mm wide and ~ 9mm thick; the head is ~ 13mm wide, ~ 9mm thick and ~ 34mm long. The Bearded Dragon has a neck ~ 22mm wide and ~ 18mm thick; the head is ~ 40mm at the widest point, ~ 22mm thick, and ~ 47mm long. These devices must be comfortable for the laboratory reptiles. The devices should also be easy to use and clean by the researchers to keep the reptiles healthy. There are several design features that must be considered in both pairs of pneumotachometer devices. All pneumotachometer device designs need to have two ports, one to allow air intake for inhalation and the second to allow exhaled air to pass to the pneumotachometer for data collection. The air intake port should be positioned so that the air flowing into the device does not blow directly into the reptile’s face to avoid drying out the reptile’s eyes. Our devices need to be rigid and airtight to ensure durability for experiments lasting two to eight hours and to prevent experimental errors in the pneumotachograph readings caused by air leakage. The devices need to be lightweight so that the reptiles are not strained or made uncomfortable. The devices must be made of non-toxic, allergen-free materials so that the reptiles are not harmed. The device for the Bearded Dragon has a few additional design challenges. This device must fit snugly and create an airtight seal around the Bearded Dragon’s spiky head using materials resistant to the Dragon’s spikes. Also, the device needs to be secure and resistant to the Bearded Dragon’s attempts to push the mask off with its forelegs. The Bearded Dragon has a mandible that is approximately 31.5 mm long, and the device must account for this length [6]. Pneumotachometry Pneumotachometry is a method used to measure the frequency, tidal volume, and peak air flow of breathing in animals and humans. A pressure difference exists between the two sides of a semipermeable resistive membrane (Figure 3). The high pressure on one side of the membrane forces the air to flow to the low pressure zone on the other side of the membrane. This air flow is directly proportional to the resistance of the membrane. The equation that governs this relationship is ∆P = QR, where ∆P is the pressure difference, Q is the air flow, and R is the resistance of the membrane to air flow [8]. Since we cannot directly measure air flow, we must measure the pressure difference. By hooking a simple differential pressure transducer up to the two sides of the membrane we can obtain this measurement. A sample reading from a pneumotachometer is shown in Figure 4.Figure 4: Data from a Pneumotachometer. The peaks represent the tidal volume and the distance between the peaks represents the time between the breaths [6]. Figure 3: Pneumotachograph Schematic [8]. Physical Characteristics of Corn Snakes and Bearded Dragons Corn Snakes have smooth even skin and narrow heads. The size of a Corn Snake’s head does not increase proportionally with body size. Snakes can also dislocate their jaws. Bearded dragons have very spiky skin on the sides of the head and prominent brow ridges on the top of the head. Their skulls are much wider than their necks. Bearded Dragons can breathe through their mouths if their nose is blocked. Reptile Opioid Research The effects of opioids on reptiles are widely unknown even though opioids are commonly used for pain treatment in both laboratory and research settings [7]. The reptile’s response to opioid derivatives depends on which receptors (µ, κ, or δ) the species has and which receptors the specific opioid activates. Pain and breathing suppression are both effects of opioids on reptiles but they are not dependent on each other. For instance, the reptile
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