Nitrogen and Cognitive Impairment

Transcription

1 Nitrogen and Cognitive Impairment How do the impairment effects of dissolved nitrogen in the blood affect problem solving? Subject: Biology Word count: 3278 Candidate Name: Alejandro Arboleda Gomez Candidate Number: Session: May 2016 School: Mont Kiara International School Table of Contents

2 Abstract 2 Nitrogen and Body Impairment 3 Nitrogen and Diving: Decompression Sickness 3 Decompression Theory 5 Nitrogen Narcosis 5 SEASFiRE and PADI 6 Experiment: Design Controlled Variables 7 Experiment: Procedure 8 Scoring Results 10 Trends: Efficiency of Problem Solving skills vs. Depth and Time vs. Depth 13 Conclusion 15 Work Cited 17 Appendix 18 Arboleda 1

3 Abstract Underwater, divers are always exposed to certain cognitive impairment due to the increased levels of nitrogen dissolved in their blood. The aim of this essay is to investigate the extent of how increased levels of dissolved nitrogen in the blood impair drivers abilities to problem solve. The research question formed was: How do the impairment effects of nitrogen dissolved in the blood affect problem solving? The main focus of the essay is the concept of how nitrogen narcosis increasingly impairs a diver as depth underwater is increased. In order to investigate the research question, an experiment was done on advanced divers were they performed Pre SAT math questions at different depths underwater. To further explore the impairment felt underwater, stressors were added in additional trails allowing to see full impairment experienced by a diver and confirm the results from narcosis alone. It was concluded that even at shallow depth were diving as a hobby is allowed, narcosis effects are significant. The divers efficiency and accuracy of problem solving decreased with the increase in depth; their Pre SAT math question results got lower and time of completion increased with depth. With the added stressors, impairment became even more significant affecting the divers abilities vastly compared to their results on land. Divers are always aware that they are under some impairment underwater and safety precaution are always kept in mind. Word count 228 Arboleda 2

4 Nitrogen and Body Impairment Nitrogen is very important to the human body. It is found in various body tissues and most importantly in proteins and DNA in turn making it part of the genetic code (Water Treatment Solutions). Eating an excess of foods with nitrogen compounds, most commonly as dietary protein, can actually increase the amount of bodily proteins and nitrogenous compounds such as muscle tissue. This would be seen in the growth stages of a human being, including pregnancy (Bender, David A.). Yet, nitrogen is also the cause of many problematic situations in the human body in many of its other compound forms. Nitrate, a form of nitrogen found in water or soil, causes Vitamin A shortages and decreased functioning in the thyroid gland, and nitrite, another form of nitrogen, can decrease reactions, haemoglobin and oxygen. These forms of nitrogen come from industrial processes as well as overuse of fertilisers in soils. One form of nitrogen in particular causes certain impairment of the body and the muscles, it is called nitric oxide. Nitric oxide can be produced from combustion processes. It causes certain relaxation in the muscle to decrease their performance and function. There is an enzyme that produces these molecules in our body which actually helps with blood flow to certain areas of need. Yet over excess of this molecule can be very harmful to the body (Water Treatment Solutions). Nitrogen and Diving: Decompression Sickness Nitrogen makes up about 78% of the air. Since it is an inert gas, it does not take part in cellular respiration and is not 'used' by the body, it dissolves in one s blood via the exchange of gases from the lungs to the blood. The blood then carries the gas all over the body to different bodily tissues. At sea level, the air pressure is around 1 bar. Since nitrogen makes up about 78% of the air, its partial pressure, the pressure a gas has in a mixture of gases is around 0.78 bar at Arboleda 3

5 sea level (Models, Neo-Haldane). Dalton s Law of Partial Pressure states that the pressure of a gas is the sum of all the partial pressures of its individual components thus why nitrogen partial pressure in the air is 0.78 bar (Blauch, David N.). 10 meters below sea level, atmospheric pressure rises to around 2 bar, hence the nitrogen partial pressure in the air that the diver breathes from their tank will be 1.56 bar. As a result, more nitrogen dissolves in their blood because its partial pressure has risen compared to what it was at sea level. Since gases dissolving into liquids is an equilibrium process, divers must be very aware of levels of nitrogen absorption. Once a diver rises from a deeper depth, but the body retains some dissolved nitrogen, which slowly dissipates as the partial pressure is reduced due to them being supersaturated with nitrogen as they have a higher partial pressure than their surrounding atmosphere (Models, Neo-Haldane). To establish a state of equilibrium, the nitrogen in the bodily tissues will form microbubbles turning back into a gas which is stated by Henry s Law where a concentration of a solute gas in a solution is directly proportional to the partial pressure of that gas above the solution. Thus as pressure is decreased, nitrogen turns back into a gas to establish equilibrium (Plambeck, James A.). Ascending too quickly can cause larger bubbles to form which can clot veins and arteries, leading to a set of conditions known as decompression sickness (Models, Neo-Haldane). Divers must carefully monitor their depths and dive times. They must control their ascent rate to less than 18 metres per minute at the end of a dive. It is also recommended that divers complete a safety stop, waiting at five meters depth for three minutes before completing their ascent at the end of a dive. This allows the levels of nitrogen in the body to reduce significantly. Then, when a diver rises to the surface, the supersaturation that occurs should be so insignificant so as to cause no harm to the diver. If a diver exceeds their physical limits or ascends too quickly and Arboleda 4

6 decompression sickness occurs, they must go to a hyperbaric chamber, where the atmospheric pressure can be controlled. They are then subjected to greater pressure again, and slowly decompressed so that the nitrogen safely leaves their tissues (Gibb, Natalie). Decompression Theory With information about partial pressure, decompression sickness and theoretical tissues a decompression theory was formed. In 1908 by an English physiologist named John Scott Haldane. He used a body model with hypothetical compartments. The theory was later improved by the US Navy and Schreiner in throughout the 50 s, 60 s and 70 s. The theory describes the relationship inert gas uptake and saturation of bodily tissues when breathing air and other gases at pressures other than normal atmospheric pressure. The theory underpin models developed specifically for scuba diving, which set depth and time limits for divers, so that they can dive safely, in terms of both absorbing nitrogen and allowing it to dissipate from their bodies safely (Models, Neo-Haldane). Nitrogen Narcosis Nitrogen narcosis is an altered state of mind that can occur while diving when absorbing too much nitrogen at a high partial pressure. The average depth at which a diver starts to experience symptoms of narcosis is around 30 meters below sea level. Narcosis has an anaesthetic effect on a diver very similar to that of laughing gas, which is another oxide of nitrogen called nitrous oxide. A diver experiences an emotional effect as well as mental and physical impairment. Depending on the situation a diver might feel overly relaxed and euphoric or very stressed. When divers feel overly relaxed, they may fail to react appropriately or think logically in a potentially harmful or dangerous situation. When stressed, divers might perceive Arboleda 5

7 problems which do not exist which may cause them to damage gear or themselves. Narcosis affects a diver's ability to reason, evaluate and react to situations effectively. Nitrogen absorption can slow down a diver s thinking and reaction times, even without noticeable symptoms of narcosis. Divers may have trouble accomplishing tasks that need a specific set of skills as well as a certain amount of precision of movements on deep dives. Another physical effect of divers from narcosis is decreased control of thermoregulation, the ability to control one s body temperature. The shivering that the body does to warm itself is reduced in amplification as the diver becomes more relaxed. Being mentally impaired they might not even realise how cold they really are. This could lead to hypothermia (Gibb, Natalie). As diver reach lower depths, they are more likely to experience more critical narcosis effects: According to Table 1: Signs and Symptoms of Narcosis, in the appendix, the deeper a diver goes underwater, the symptoms from nitrogen narcosis become more aggressive and severe. After meters, a diver's ability to problem solve and have proper judgement is severely impaired and can even lead to death at deeper depths. Divers are trained to handle and detect nitrogen narcosis underwater. The buddy system in diving means divers look out for each other and if any effects are seen swimming to shallower depth should decrease the symptoms. SEASFiRE and PADI SEASFiRE is an organization which attempts to educate and make a learning environment in and about the ocean and marine life. Its programmes merge learning in subjects (MKIS SEASFiRE) Arboleda 6

8 such as biology (including marine biology), the arts, and multimedia, using scuba diving to achieve specific academic goals. The program includes dive training, which is delivered to PADI (Professional Association of Dive Instructors) standards. PADI is the largest dive certification organisation in the world, PADI instruction covers such topics as decompression sickness and nitrogen narcosis as well as environmental issues which the oceans are facing at this moment in time. SEASFiRE helps a number of high school student to not only become divers but also be educated about marine life, design diving experiments, and contribute to helping the oceans with dives such as dive against debris to clean up the ocean floor. Experiment: Design Controlled Variables During the SEASFiRE trip of March/April 2015, an experiment was carried out to test the effects of nitrogen absorption on cognitive problem solving skills The experiment consisted of making scuba divers who were high school students take a test at various depths (on different dives) to see their rate and effectiveness of completion of the test. To design the experiment, there were many variables that had to be controlled to test for nitrogen levels alone: i. Standardised Testing and Level of Knowledge: For all the individuals to have as equal as possible of chance to do the test as correctly as possible a standardised test was formed from Pre SAT math questions. This test is the practice round of the SAT which is also another standardised form of testing. The Pre SAT divides questions into three categories: easy, medium and hard. The tests formed for the experiment had two easy questions, five medium, and five hard. There were a total of four different test made with all different questions, yet they followed the same Arboleda 7

9 ratio of 2:5:5. The questioned were all multiple choice and had to also be able to answered without the use of a calculator. The Pre SAT was designed to have problems at a 11th grade student s level. The participants were either from 11th or 12th grade (senior students) and were all certified advanced open water divers. Thus, they should have similar levels of underwater skills and knowledge so that no one would be under more physical or atmospheric stress than the other. ii. Stress: Possibly the most important variable to control was environmental and diving stressors. Underwater a diver has multiple things to think about: buoyancy, breathing, not losing the group or your diving buddy, etc. So the tests were designed to be done on a flat area at the ocean floor surrounded by rock so no current could get through. Divers would not have to worry about buoyancy or losing the group as they were not swimming or fighting even the slightest current. Since the experiment was always performed at the beginning of the dive, air consumption was not a big issue to worry about as divers always had plenty of air left in their tanks, but a warning was still given that if a diver had under 70 bar, the dive must be terminated. Three supervisors (both students and instructors) were overseeing the whole test to ensure external stressors were minimised. Experiment: Procedure For every dive the procedure was the same: i. Every diver was given a test, slate, and pencil before the start of the dive and asked to bring this with them. Arboleda 8

10 i. At the beginning of the dive, the group descended to the desired depth, and waited until everyone is settled. This always took at least five minutes so that there would be a reasonable level of nitrogen absorption taking place. ii. The divers would either sit or lie down on the ocean floor to begin the test, taking out their tests, slates and pencils. iii. One supervisor would tell the group the start the test and with a stopwatch time then all simultaneously. The time limit for the test was 10 minutes. iv. Divers would write their answers on their slate. v. Once an individual was done they would raise their hand. The supervisor timing would look at the stopwatch and write down the time the individual finished while another supervisor would collect the test, slate and pencils from the diver. vi. Once everyone was done and materials were collected, everyone moved as a group to conduct a dive with other activities not concerning the experiment. A test was also performed on land in the same exact way with the divers sitting or lying down on the floor while writing their answers on a slate and all being timed. This test was used to compare later compare to those done underwater. Arboleda 9

11 Scoring Results Based on the theory behind nitrogen narcosis, one infers that the number of correct answers would diminish as a diver goes lower in depth. In Figure 1 one can see that the decrease in correct answers was not seen until 24 meters. This might have been due to only having two easy questions in each exam. Yet the expected trend is seen where in the lower depth more divers are only getting one answer correct rather than two. Figure 1: Average Easy Questions Answered Correctly vs. Depth Arboleda 10

12 Figure 2 supports expected results. On land the average score was 3.5 out of 5 and that decreased to 2.5 by 24 meters. When looking at the the correct answers from 0 m to 12 m, they decrease much more significantly than from 12 m to 24. Since in double the depth the consistency of correct answers was similar, one could infer that there is only slight variation in impairment between recreational diving depths. Figure 2: Average Easy Medium Answered Correctly vs. Depth Arboleda 11

13 Figure 3 shows a very similar trend between the hard and medium difficulty questions. The significant drop in answers happened between 0 m and 12 m again from 2.33 to 1.5 answers correct of out 5 respectively. Between 24 m and 12 m again there seem to be that the impairment caused around the recreational depths slows does not increase significantly throughout. Figure 3: Average Hard Questions Answered Correctly vs. Depth From 10 to 30 meters, we can observe that there is already mild impairment caused by nitrogen narcosis. Because of the range in depth, the range in impairment was not boldly defined but still clearly seen. Many of the divers were surprised when they surfaced and looked at the questions again. Some were shocked at how hard the question seemed underwater; they were not aware that they were even under any impairment. But now that they were on land, they saw how simple some of the questions they missed actually were. Not only did the divers cognitive abilities become compromised, but they also found a simple task difficult compared to the same scenario on land. Even though only mild mental impairment was experienced, this shows the Arboleda 12

14 dangers of narcosis as divers are already experiencing some cognitive impairment before they notice any symptoms. Stress Results: An extra Dive Nitrogen narcosis is not the only factor affecting divers underwater. Most of the time, divers do not experience such calm environments as the ones they were under when performing this experiment. To test the full impairment of being underwater, divers were put to take a test at 18 m underwater while sitting in a mild current. With a current, it is very hard for a diver to stay stationary. Not only does the diver have to focus on completing the test, but now they have to focus on staying with the group and remaining as stationary as possible amongst other stressors. Figure 4 below shows that the number of questions answered correctly in each category in the 18 m depth was even lower that any of the other depths. In all three categories, the average was close to 1 question correct. Even though nitrogen narcosis plays a big role on cognitive abilities of divers underwater, many more stressful situation can cause further impairment. factors can come into play and it appears that a Arboleda 13

15 Easy Correctly Figure 5: Answered Figure 6: Average Correctly vs. Depth Collecting purposes: the first combined range of Figure 4: Average Questions Answered vs. Depth Average Medium Questions Correctly vs. Depth Hard Questions Answered this data had two main was to show a full impairment factors that a diver experiences underwater, and the second was to confirm that only the effects of narcosis were isolated for the other depths as best as possible. Because of the many stressors underwater, one needs to make sure that all other variables are controlled in order to test in this kind of environment. The test done at 18m helps to prove that narcosis effects were isolated and that only stressors such as breathing, which are impossible to remove, were left. If not all stressors had removed in the other depths, the results from the 18 m dive would have been higher than those of 24 m or even 12 m which could have compromised the data. Trends: Efficiency of Problem Solving skills vs. Depth and Time vs. Depth Arboleda 14

16 Looking at the average results of the divers trends of both the accuracy and efficiency of their cognitive skills in relation problem solving to depth can be seen: Figure 7: Average Questions Answered Correctly vs. Depth Arboleda 15

17 One can infer that as one goes deeper underwater, the less accurate you will be at problem solving. Figure 7 shows the trend line in relation to the total questions answered correctly versus depth, and one can extrapolate to see that there will be a depth eventually reached where cognitive functioning is very minimum. This was a very simple task yet, the trend line shows that there is a significant decrease in accuracy in just the recreational diving limits. Also, one can see clearly in Figure 6 the significant difference between the test done at 18 m and the rest. It is clearly seen that there are other stressors that were not controlled and took a toll in the accuracy of the divers. Arboleda 16

18 Figure 8: Average Time for Test Completion at Depth Figure 9: Time for Test Completion vs. Depth The time for test Completion was also recorded. The trend was very much the expected one. Divers took longer to complete the test at the deeper depths. Figure 8 and Figure 9 show two graphs that prove there is a continuous increase in the time for test completion throughout all the dives. Almost as fast as the depth increases, there is an increase in time for test completion. From both graphs one can also infer that there will be a depth reached where even this experiment can take over 30 minutes to do when it was designed for less than 10. Yet, this data produces anomaly with the numbers for 18 m. At 18 m it took an average of 9:15 minutes to complete the test yet at 24 m it took 9:28 even though the 18 m had harsher conditions. This does not fit with the rest of the data because at 18 m there were the least answers correctly, yet it follows the pattern in time as if the conditions were the same as in the other dives. This could have been due to lack of focus or the concentration of just finishing the test in order to deal with the other stressors which led to a faster time of completion than expected. The data could also suggest that stressors, including nitrogen narcosis, at recreational diving depths affect more of the accuracy of judgment in cognitive problem solving than the rate at of thought processing for problem solving. This means that stressors underwater are less likely to slow a diver down, but are more likely to cloud their thinking instead. Conclusion In conclusion, the effects of nitrogen dissolved in bodily tissues are highly significant. Divers in this experiment, on average. experienced noticeable effects of nitrogen narcosis in simple problem solving skills in SAT mathematics questions. The effects of nitrogen narcosis Arboleda 17

19 were already being seen at only 12 meters underwater and by 24 meters it was very clear that narcosis had significantly impaired the divers in comparison to then on land. This experiment dealt with very simple problem solving skills, but there are endless possible events that can happen underwater which will require a lot more mental focus and skills. Diving can be enjoyable when the individuals are aware and ready for any scenario that one might face underwater. It is very important to be educated about the risks of nitrogen absorption. The world underwater is a beautiful and majestic place full of things to explore, see, and discover. Organizations such as PADI and SEASFiRE are some of the many that ensure divers can experience underwater environments to the fullest. With enough education, anyone can safely explore the world beneath the waves where life has taken many new and amazing forms. Arboleda 18

20 Work Cited Bender, David A. "The Virtual Laboratory: Nitrogen Balance." Untitled Document. Dept. of Biochemistry and Molecular Biology, UCL, n.d. Web. 22 Feb < Blauch, David N. "Gas Laws." : Dalton's Law. N.p., Web. 12 Nov "Dive Theory - The Recreational Dive Planner (RDP)." IDC Guide. N.p., n.d. Web. < Gibb, Natalie. "What Is Nitrogen Narcosis." Aboutsports. N.p., n.d. Web. <http//scuba.about.com/divemedicinesafety/nitrogen-narcosis-and-scuba-diving-what- Is-Narcosis-And-How-Does-It-Feel.htm>. Lippmann, John; Mitchell, Simon J. (2005). "Nitrogen narcosis". Deeper into Diving (2nd ed.). Victoria, Australia: J. L. Publications. pp ISBN X.OCLC "MKIS SEASFiRE 2015." MKIS N.p., Web. 13 Nov Models, Neo-Haldane. "Decompression Theory." Deep Ocean Diving's Diving Science. N.p., n.d. Web. <http// Plambeck, James A. "Introductory University Chemistry I.". Henry's Law and the Solubility of Gases. N.p., Web. 12 Nov "The Placebo Effect: What Is It?" WebMD. WebMD, n.d. Web. 04 Oct "Water Treatment Solutions." Nitrogen (N). N.p., n.d. Web. 04 Aug Arboleda 19

21 Appendix Pressure (bar) Depth (m) Symptoms Unnoticeable symptoms Mild impairment of performance Mildly impaired reasoning and euphoria Delayed response to visual and auditory stimuli Reasoning and memory decreased Sense of well-being, Anxiety (in murky water) Sleepiness and dizziness Confusion, lack of judgement and delayed response Hallucinations: visual and auditory Terror (in some cases) Poor concentration and loss of memory Increased symptoms as well as stress and irritation Severely impaired sight and hearing Sense of blackout, euphoria, dizziness, depression Lack of sense of time Unconsciousness Death Table 1: Signs and Symptoms of Narcosis (Lippmann, John) Arboleda 20

22 18 m Current 18 m Current Diver # Time (min) Diver # Easy Medium Hard Total / 2 3/ 5 2/ 5 7/ : / 2 2/ 5 2/ 5 5/ / 2 0/ 5 0/ 5 2/ / 2 1/ 5 0/ 5 1/ : / 2 1/ 5 0/ 5 2/ / 2 2/ 5 2/ 5 5/ 12 Figure 10: Raw Data for 18 m Arboleda 21

23 24m Controlled Environment 24 m Controlled Environment Diver # Time (min) Diver # Easy Medium Hard Total / 2 4/ 5 1/ 5 6/ / 2 3/ 5 3/ 5 9/ / 2 2/ 5 0/ 5 3/ / 2 4/ 5 0/ 5 5/ : / 2 2/ 5 3/ 5 8/ / 2 0/ 5 0/ 5 3/ 12 Arboleda 22

24 Figure 11: Raw Data for 24 m 12 m Controlled Environment 12 m Controlled Environment Diver # Time (min) Diver # Easy Medium Hard Total 1 7: / 2 3/ 5 2/ 5 7/ : / 2 5/ 5 4/ 5 10/ : / 2 2/ 5 0/ 5 4/ : / 2 1/ 5 0/ 5 3/ 12 Arboleda 23

25 5 6: / 2 4/ 5 3/ 5 9/ : / 2 1/ 5 0/ 5 3/ 12 Figure 12: Raw Data for 12 m Land Land Diver # Time (min) Diver # Easy Medium Hard Total / 2 4/ 5 4/ 5 10/ / 2 5/ 5 4/ 5 11/ 12 Arboleda 24

26 / 2 3/ 5 1/ 5 5/ / 2 3/ 5 1/ 5 5/ / 2 5/ 5 3/ 5 10/ / 2 1/ 5 1/ 5 4/ 12 Figure 13: Raw Data for 12 m Arboleda 25