CHEM STUDY GUIDE MIDTERM.docx

Sister Mary Bernard - **First officially recognized nurse to practice Nurse Anesthesia.** Alice Magaw- **MOTHER OF ANESTHESIA** **Current president of AANA- Janet Setnor (used to be Dru Riddle)** Agatha Hodgins- **founded the NANA in 1931 (name changed to AANA in 1939)** - Goldie Brangman→...

Sister Mary Bernard - **First officially recognized nurse to practice Nurse Anesthesia.** Alice Magaw- **MOTHER OF ANESTHESIA** **Current president of AANA- Janet Setnor (used to be Dru Riddle)** Agatha Hodgins- **founded the NANA in 1931 (name changed to AANA in 1939)** - Goldie Brangman→ AANA president in 1974 (GOLD STANDARD, GOLD PEOPLE) - Advocated for more diversity in race and gender in AANA - Cared for Martin Luther King Jr. after being shot Ether and nitrous oxide= first anesthetic agents used 1st CRNA certification boarding exam was given in 1945 - President Reagan signed into law the Omnibus Budget Reconciliation Act of 1986 allowed direct reimbursement to CRNAs via Medicare & Medicaid Know the definitions of augment and attenuate - Augment: make something greater by adding to it; increase - Attenuate: the reduction of the force, effect, or value of something 27. To be an effective buffer, the acid must - **Have a p*K*a nearly equal to the desired pH (correct answer)** - Be a strong acid - Have a strong conjugate base - All of these Know vapor pressures of Isoflurane, Sevoflurane, Desflurane, Halothane the partial pressures of these: \"**S**ome **E**lephants **I**n **H**aiti **D**ied\" - Sevoflurane: 160 (in Nagelhout page 228) - Enflurane: 172 - Isoflurane: 240 - H: Halothane: 244 - D: desflurane 669 Know about the 70/30 rule with nitrous - effective nitrous oxide/oxygen anesthesia requires control of relative concentrations at or close to 70/30. Less than 70% nitrous oxide is unlikely to guarantee unconsciousness (Rosen, 1959) and less than 30% oxygen is unlikely to guarantee main- tenance of arterial Po, above 80 mm Hg **A full O2 tank is 660L and is 2000psi** Avogadro's number/ Avogadro\'s hypothesis  Avogadro\'s hypothesis states that equal volumes of all gasses at the same temperature and pressure contain equal numbers of particles What causes rusting of iron **OXIDATION (Losing of electrons)** Vapor Pressure of all of them! (Dennis Has Intercourse Every Sunday) lol Most abundant metal in the body- **CALCIUM (iron in the presentation so i guess choose that)** \*PLASMA is the most abundant matter\* Law of Force equation Metal that makes RBC- **IRON (nickel in the presentation so i guess pick that) lol** Volume the same what's the relationship with t and pressure= they correlate (Charles Law) Two syringes with different needles the bigger will have = 16 times the speed Law of Laplace  VP= temperature \*ALL THE EQUATIONS- Partial Pressures (know the CO2 and O2) (Partial pressure of gas when given to pt) 1 atm=760mmhg=760torr=1bar (1033 mbar) =100kpa=1033 cmH2O- (answer was 55 kPA- NOT an equivalent of this) pH=pKa - weak acid (non-ionized concentration is equal to ionized concentration) Fisher projection = tetra TERFA & IFNA definitions - **TEFRA (Tax Equity and Fiscal Responsibility Act) was designed to control costs and ensured that anesthesiologists demonstrated that certain services were provided as part of a given anesthetic to qualify for payment.** - **IFNA (International Federation of Nurse Anesthetists)- 36** countries are members of the coalition of national associations of nurse anesthetists Know the people (Agatha vs Alice & who they worked with) The separation of substances in a solution= **Sedimentation** Reynold's Number inversely related to n =viscosity Invention of the periodic table by who- **Dmitri Mendeleev** Laminar Flow is dependant on what law- Pouseille's Law  Turbulent flow is dependent on gas density (Graham's Law) Volume the same what's the relationship with t and pressure= they correlate (Charles Law) Bonds strongest to weakest (Covalent \> Ionic \> Polar Covalent \>Van de Waals) IDEAL GAS LAW (CAN THIS GUY'S PENIS BE VAGINA)- label upside down triangle starting on R side and going clockwise **Henry's Law** - At a constant temperature, the amount of gas that dissolves in a solution is directly proportional to the partial pressure of that gas over the solution - The higher the gas pressure, the more it will dissolve into a liquid - Ex: soda - Note: increase in temp will decrease the gas' solubility in the liquid - Application: anesthetic emergence is slower in a hypothermic pt - Solubility coefficients: - O2= 0.003 - Multiplying the PaO2 by 0.003 will tell us how much O2 is in the blood - CO2= 0.067 - Multiple by PaCO2 to find out how much CO2 in blood **Lecture 2 - Chemistry, Biochemistry, and Physics of Anesthesia** **Basics of Organic** - Organic Materials - Made predominantly of hydrogen and carbon atoms - Make up all living organisms - Inorganic Materials - Denote compounds which do not contain carbon **What is Matter?** - Matter - occupies space and mass - Anything that occupies space and mass - Atoms are the basic building blocks of all matter - Solids, liquids, gas and plasma - Chemistry studies matter and the changes it undergoes - Elements -are pure chemical substances that can't be broken down into anything **What constitutes make up the universe?** 1. Energy (Physics) 2. Matter (Chemistry/Biochemistry) - Solids: resistant to changes in shape & volume - Liquids: fluids that have minimal compressibility & may change volume with changes in pressure and temperature - Gases: are compressible & easily change volume with changes in temperature & pressure - All these changes can be physical or chemical - Physical change will transform a substance into a different state but still remain the same substance - Chemical changes will make a new substance **Atoms** - Atoms: Basic building blocks of matter (consists of 3 components) - 1\. [P]rotons (+ [P]ositive charge) - 2\. [N]eutrons ([N]o charge) -- think [N]eutral - 3\. Electrons (- negative charge) - An atom is any particle of matter and its most basic level and is surrounded by one or more electrons (-). - An atom is the smallest unit of element, can't be divided - The nucleus is heavy and contains protons (+) and neutrons (neutron) - Electrons orbit the nucleus in an "electron cloud" - You have different shells of electrons - The negative (electron) charge is attracted to the positive charge of the nucleus - This keeps the electrons from flying away. **Atomic Structure** - **Atomic number = number of protons (in nucleus)** - The chemical properties of elements are related to the **number and characteristics** of the electrons in the outermost orbitals - Number of protons never change - Electrons are arranged in shells - Number of electrons is the same as the number of protons - Each shell must be complete before electrons can fill the next shell - Incomplete shell allows for an atom to react with another atom - A full shell = atom is non-reactive - **Valence electrons = electrons in the Outermost shell** - **Are the most energetic shells** **Definitions** - Matter: Composed of atoms. Has mass and takes up space! - Elements: composed of only two kinds of matter. There are 118 elements that have been identified. - 25 elements are essential for life - Four elements make up about 96% of the mass of most living organisms - **Carbon, Oxygen, Hydrogen, and Nitrogen** - When you combine two elements together you form a compound - Elements are composed of atoms *that are all the same* - Molecules are the smallest part of a substance *that has all the physical and chemical properties* of that substance. - Molecules are made up of one or more atoms. - Compounds are composed of molecules or ion pairs that *are combination of atoms of at least 2 different elements* - ***Atoms ---\> Matter ---\> 2 Matter ---\> Element (atoms all the same)---\> 2 elements ---\> Compound*** **Atomic Weights** - Atoms of elements have different masses - Atomic Mass Unit (AMU) of an element is a measure of its atomic mass. Every element is a different number - The mass of an atom is the sum of its **protons** & **neutrons** - The number of protons NEVER change - For a given element the number of protons (atomic number) is fixed (never changes - top right number) - Protons are always the same, but the number of neutrons may vary and that's when you get an **isotope** **Periodic Table** - Created 1800s by Russian chemist **Dmitri Mendeleev** - **Iron** is the most abundant metal in the body - Nickel is used to produce red blood cells in the body - **NOTE: Dmitri Mendeleev made the periodic table** **Electrical Charge** - Positive charge - \#electrons is less than \# protons  - Neutral charge - \#electrons is equal to \# protons - Negative charge - \# electrons is greater than \# protons - Cation - atom with + charge (lost electrons) - Anion - atom with - with negative charge (gained electron) **Atomic Bonding** - Ionic = complete transfer of valence electrons - When 1 or more electrons is transferred from one atom to another resulting in a positive or negative charge to that atom ---\> making it an ion - Acids & bases - Covalent = equal sharing of valence electrons - Sharing of one or more electrons pairs between atoms (Co-parenting) - Polar covalent = unequal sharing of valence electrons - Water (polar bond) = H2O - Oxygen is negative, 2 hydrogens are positive - \+ AND - causing hydrogen bonding of water, because the oxygen molecule (-) is attracted to the hydrogen (2 +) - Cold "B" **Van de Waals Force** - Electrons are orbiting the molecule in constant motion - It creates a temporary **+ or --** charge in the molecule at any given time - Resulting in a weak bonding ---\> the electron rich areas of a molecule are attracted to a weak area on another molecule - Can break easily - Weak pull that pulls things together) - **Bonds in order of strength** - **Covalent \> Ionic \> Polar covalent \> Van der Waals** **States of Matter** - Solids - Both definite volume and definitive shape - Organized - Liquids - Characterized by a definite volume, but adopt the shape of their container. - Volume stays the same - Gasses - Have neither a definite volume nor a definite shape - Particles moving freely - Vapor Pressure **John Dalton's Atomic Theory (1803)** - Developed a relationship between elements and atoms, introduced that compounds are a combination of elements, and the concept of atomic mass - All matter is comprised of tiny, definite particles called atoms. - Atoms are indivisible and indestructible. - All atoms of a particular element share identical properties, including weight. - Atoms of different elements contain different masses - Compounds are formed by a combination of 2 or more different kinds of atoms (H2O) - Chemical reactions do not create, destroy, or change atoms into atoms of other elements. - Chemical reactions cause atoms to recombine into new substances. **Aqueous Solution** - The word aqueous is derived from a Latin word - Aqueous Solution: The solution which is formed by dissolving a substance in water - Water is present in large amount - solvent - Solution - forms when two or more forms of matter are distributed evenly in a mixture (like sodium chloride) - Why is water a universal solvent - Water has the ability to dissolve many substances - Water is a polar covalent compound, only other polar covalent compounds are soluble in water (salt and sugar) - Nonpolar compounds are not soluble in water - oil and petroleum - What happens when a substance is dissolved in water? - Dissolved in water equally distributed - Dissociates into the sodium and chloride ions **Do Aqueous Solutions Conduct Electricity?** - Yes! - Free ion in aqueous solution will conduct electricity - Left as free ions that conduct electricity - All ionic compounds conduct electricity - Solution that conducts electricity - ELECTROLYTES - Those who don't conduct electricity are non-electrolytes - Give aqueous solutions to patients - LR and Sodium chloride - LR give hyperkalemia - high K - such as renal patients - Sodium chloride - high chloride **Osmosis & Diffusion** - Osmosis is net movement of water across a semipermeable membrane - Solute (salt) and solvent (water) - Water moves from areas of low solute ---\> to high solute concentration - Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. **Tonicity** - Comparison of the osmolarity of a solution to the osmolarity of plasma. - Hypertonic solution - 3% to prevent cerebral edema in neuro. patients with increased ICP - Hypotonic - (hippo) swells - Hypertonic - (skinny and tiny) hyper - Isotonic (the same) no transfer of water, same size **Electrolytes** - Electricity relates to the flow of charged particles under the influence of an electrical field. - Electricity requires charged particles that are freely moving around. - Ionic Compounds that dissolve in water are strong electrolytes - Molecular Compounds that dissolve in water are normally non-electrolytes (SUGAR) - Electrolytes are a substance that dissolves in water to give a solution a means to conduct electricity. - NaCl is a very strong electrolyte (can shock patient) - In anesthesia when you have a pt who gets a TURP, they instill sodium chloride to visualize the prostate. This can potentially shock the patient because that solution is charged - All soluble ionic compounds are strong electrolytes - Strong acids are strong electrolytes (HCl) **Fluid Compartments** - Total body weight = 60% Water & 40% is solids (proteins, lipids, minerals, carbs) - Numbers in anesthesia usually regards to a 70kg patient - Plasma is the MOST COMMON state in matter **Redox Reactions** - Redox reactions are everywhere - In general biology, we talk about cellular respiration and photosynthesis extensively and both are redox reactions - An oxidation-reduction (redox) reaction is a type of chemical reaction that *involves a transfer of electrons between two species*. - It's a reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron. - Example: To protect iron, its covered by a layer of zinc, stops water and oxygen from causing redox reaction so it doesn't rust - Bleach - removes stain by redox reaction - Students memorize which components are oxidized and which are reduced - Oxidation - transfer electrons (reducing agent) Gains Oxygen/Loses Hydrogen - Reduction - gaining electrons (oxidizing agent) Loses Oxygen/Gains Hydrogen - Remember Oxygen is an ass, always takes electrons **Chemical Reactions** - Free radical analogy - Spinning a plate around (electron), outermost shells of the plate have two weights and are evenly distributed. One weight is removed, its gonna fall - Free radical (electron) is unstable  - Free radicals occur when adding an oxygen to another compound - Causing damage - damage tissue and DNA - What is Oxidation? - loss of electrons - creates a positive charge with loss of electrons - Examples: - Hydrogen peroxide - Rusty car (metals, iron) - Brown apple - Oxidation - exposed to oxygen - Antioxidant - acids (lemon) preventing oxidation by adding an electron, and donates electron to make things more stable - Antioxidants donate and electron to an unstable electron (free radical) **Simple Rules for Oxidative and Reduction of Organic Compounds** - Oxidation - transfer electrons - During oxidation there's a loss of an electron and it makes it more positive - Reduction - gaining electrons - Reducing charge - making it more negative with the gain of electrons **Examples of Oxidizers** - Glucose - DM pts ---\> high glucose in the body creates high levels of oxidation when metabolized - Create large number of free radicals - foot necrosis - When take antioxidants like zinc, vitamin C, D or E, or ketones - they act as antioxidants and reduce complications like DM - Oxidative stress we become depleted in vitamins A, C, E, D - Help reduce damage done to the body - Vegetables Oils - highly unstable seed oils (soy corn, cotton seed, canola) causes oxidative stress. - Iron - Rust ---\> Oxygen and iron creates rust - Too much iron in the body is dangerous - can get oxidation too (like red meat) - Chemicals - Pollution - Oxidative stress and inflammation - Low Antioxidants - Highly processed foods - Advanced lipid oxidation end products created - more free radicals - Too many oxidizers ---\> oxidative stress **Acids** - Are proton donor - pH \ - **Types of Acids** - Weak acids do not ionize completely: - boric nitrous phosphoric and sulfurous - Example: Morphine sulfate (base) (sulfuric acid) - Base and acids come together - All drugs like morphine, are either weak acids or weak bases - Drugs are salts - make them stable - When you combine morphine (basic) with sulfuric acid (acid) ---\ stable when placed back into the body - Acid and base separates and work on receptors for pain relief (morphine) - They either become ionized or non-ionized when placed back into the body - Example: Scopolamine (for nausea) - Non- ionized so can cross blood brain barrier - Strong acids ionize completely: - Hydrochloric, Nitric, Sephora, Hydriodic - NOTE: Weak acids are best absorbed in the proximal duodenum, - NOTE: Lidocaine is a weak base, and Pus is a weak acid. Therefore, if you inject the base medicine into the acidic pus they neutralize. **Bases** - Are alkaline agents that produce hydrogen ions (OH \[hydroxide\] in water) - PH \> 7 - Neutralize acids - A proton acceptor and can conduct electricity - Typically have a hydrogen ion- NaOH - Tend to be negatively charged - Are corrosive and caustic (corrosion -\> ammonia, baking soda) - NOTE: Weak bases are best absorbed in the distal ileum **Henderson-Hasselbalch Equation** - The Henderson-Hasselbalch equation provides a relationship between the pH of acids (in aqueous solutions) and their PKA (acid dissociation constant). - Relationship between weak acid and conjugate base = pH - You can use this formula to determine if patient will receive the drug if its ionized or non-ionized (can it cross blood brain barrier) - NOTE: When you use morphine (conjugate base) combined with sulfuric acid (conjugate acid) in the equation, you determine how much of each medication is required to make a non-ionized vs ionized med (example: you need nonionized to cross the BBB) **Salt** - Salt is a neutral substance produced from the reaction of an acid and a base. - Composed of (-) ion of an acid and the (+) of a base. - pH of a salt solution depends on the acid base strength of the acid or base which it is derived from - One of the products of a Neutralization Reaction - Examples: KCL, MgSO4, Na3PO4 **Neutralization Reaction** - If we take two solutions, one acidic and one base = salt and water - Happens all the time - always - Example: Elderly people - usually on anti-acid drug, we give meds used to neutralize reactions **Lecture 3 - Chemistry, Biochemistry, and Physics of Anesthesia** **What is Biochemistry?** - Study of chemistry and chemical process that occur in living systems - Focuses on biomolecules that are the building blocks for living organisms (chemistry of life) - Domain of large molecules - proteins and DNA **Metabolism** - Chemical process by which molecules in the body break down the food we eat to use as energy. - Nutrition comes into play - Health is governed by biochemistry, and all diseases have molecular base. Our entire body is made out of various molecules  **Enzymes** **Stages of Metabolism (Purpose - Energy Source)** - **Primary (Polymers → Monomers)** - The breakdown of large molecules into smaller molecules - Digestion and hydrolysis (chemical process in which a water molecule is added to lyse a substance) - Example: Break down of proteins into amino acids - **Secondary (Monomer → AcetylCoA)** - Breakdown of products from primary metabolism are used to produce reducing equivalence - Conversion of building blocks to acetyl-CoA - Acetyl-CoA ---\> a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism - Degradation (the breakdown) and some oxidation (transfer of an electron and adding oxygen) into smaller molecules - **Tertiary (Acetyl CoA→ Kreb → ATP)** - Reducing equivalents from secondary metabolism are being used up in an electron transport chain to produce energy - Oxidation to CO2, H20, and energy for ATP synthesis **Enzymes** - A substance, proteins, and RNA that speed up biochemical reactions by binding to an active site of a specific substrate - Enzymes are very specific to what they bind to ---\> selective and specific - An enzyme is a biological catalyst (an enzyme, it speeds up the rate of a specific chemical reaction in the cell) and almost always usually a protein (most likely) THINK CYP450. - Many of these enzymes are called co-factors - cations (+) or anions (-) - Co-factors are usually cations (+) ---\> binds to that enzyme and activate it - Modes of actions - Speed reactions - Lower reaction energy - After the processor enzymes binding to substrates, the enzyme not destroyed. Its' reused - Active site is in the enzyme and that's where the substrate binds - Amino acid composition is important in performing an enzyme substrate complex ---\> side chains of amino acid residue play an essential role in providing the specific shape to the pocket in the enzyme to bind and accommodate that substrate - Amino acid residue binds and changes the shape, size and chemical behavior of the enzyme - The picture shows how the basket changes the shape **Cytochrome P450** - Enzyme system known for the metabolism of anesthetic drugs - Known as **"mixed-function oxidase system"** - CYP450 system on patients with anti-seizure medication is highly induced - A highly induced system with anti-seizure medication would make Roc ineffective. Large amounts of medication and no effect. - Toxic to non-toxic, pro-drug to active form of a drug - Inducer - Speeds up reaction - Person who takes a lot of barbiturates or St. John's worts at home ---\> youre going to need more of the medication (fent, versed) to keep pain asleep - Inhibitor - Reduce the rate of an enzyme-catalyzed reaction or prevent enzymes to work in a normal manner - Person who drinks a lot of grapefruit juice (the inhibitor), and they take opioids (fent) or bento (versed) ---\> more effective cause enzyme is inhibited **Plasma pathways of metabolism** - **Types of enzymes that metabolize your drugs** - **Pseudocholinesterase (enzyme)** - Metabolizes Succinylcholine (paralytic) - Succinylcholine ---\> before Sugamadex (several agent today), they used to use neostigmine and glycopyrolate (takes time to wear off) - Because enzyme is in the plasma, it's metabolized a lot faster - **Nonspecific esterase (enzyme)** - Remifentanil - \"Fast on fast off" ---\> fast wake up - **Alkaline Phosphatase (enzyme)** - Frospropofol - Prodrug is converted to propel (active metabolite) by alkaline phosphate - **Hoffman Elimination (pH and Temp)** - Cisatracurium and Atracurium - Example: if you have an acidic and hypothermia patient, Cisatracurium metabolism is going to be slowed down ---\> paralyzed for longer **Cellular Communication** - Extracellular communication occurs in 3 different forms - Chemical - hormones, drugs, or neurotransmitters - Electrical - action potentials (heart) - Mechanical - pressure - Signal is received through the receptor ---\> instructs cells to perform specific functions - Converts extracellular communication to intracellular responses - Most receptors are located in the cell membrane, but some are located intracellularly too **4 Types of Receptors** - **Extracellular Receptors** - **Ion Channels** - **G-protein Coupled Receptors** - **Enzyme Linked Receptors** - **Intracellular Receptors** - Cell Membrane is composed of a phospholipid bilayer, on these layers there's fluids that make constantly make the lipids move around constantly - Fluidity is important for the proteins embedded within the cell membrane **G- Protein Coupled Receptors** - **7 transmembrane receptors (Lock and key model)** - Protein located in cell membrane ---\> transmits signals from substances to intracellular molecule ---\> GTP - Ligand binding causing signal ---\> GTP moves to an activated G protein - 5 different proteins that you can find inside the G-protein Coupled Receptors---\> Channel, transport, enzyme, receptor and structural protein - These receptors have sites to bond to the molecules noncovalently (no sharing of electrons) - Integral membrane protein that are used by cells to convert extracellular signals into intra cellular responses ---\> includes hormones and neurotransmitters - Work by opening or closing ion channel - Activating or inhibiting enzyme inside the cell - Muscarinic 2 (a part of cholinergic receptors --- REST AND DIGEST) receptors on the SA node - M2 located in the SA node will be inhibited and therefore slows down HR - A1 receptor (Example: Neo) is located on the vascular smooth muscle - Causes vasoconstriction **G- Protein Coupled Receptors Steps**  1. **1st Messenger** 2. Ligand either endogenous (hormone) or exogenous (drug) 2. **GPCR** - located in the cell membrane, multiple subunits ---\> Alpha, Beta and Gamma(Y) - Protein Stimulatory---\> Gs, Gq (turn on effectors) - Protein Inhibitory ---\> Gi (turn off effector) 3. **Effector** - Activates 2 messenger - Usually an enzyme (cAMP or phospholipase C) 4. **2nd Messenger** - Causes signal amplification (magnifies response within the cell) - cAMP, cGMP, DAG, Ca+2, IPT3 5. **Cellular Membrane** - Response from 2nd messenger is tissue specific - Once signal amplification is increased within the cell (2nd messenger)---\> increases cAMP and cause different responses within the tissue - **Example** - Muscarinic (rest and digest) receptor in SA node - Works on Gi ---\> inhibitory - Decrease signal amplification ---\> blocks signal amplification at 2nd messenger (can't go through) ---\> decreases cAMP ---\> decreases HR and contractility **Ion Channels (Lipid/Gated)** - An ion conducting pore that can either be open or closed - Open - flow with concentration gradient - Closed - prevents the flow of ions along that concentration gradient - Example: Voltage gated Na+ Channels in neuron **Lipid-Gated Channel (Ion Channel) Steps** 1. Ligand binds to the receptor 2. Receptor gate opens 3. Sodium ions flow into the cell based on their electrochemical gradient 4. K+ ions flow out the cell ("get the K out of here") - 3 in and 2 out - Cell membrane doesn't let any hydrophilic (water loving) go in ---\> very specific **Enzyme Linked Receptors (Catalytic Receptor)** - The receptor also acts as an enzyme - Enzymes are special proteins ---\> accelerate or catalyze chemical reaction - Transmembrane receptor where binding of extracellular ligands causes enzymatic activity within the cells - When it's at rest it's inactivated, when the signal binds to the receptor the domain (area of control) becomes activated - Example: insulin receptor in the skeletal muscle **Enzyme Link Receptor Steps** 1. Ligand binds to the receptor 2. Enzymes are active inside the cell 3. GTP is then transformed into cAMP **Intracellular Receptors** - Diffusion of the signal through cell membranes to bind with the receptor inside - Example: Steroids ---\> bind to the receptor by going through the cytoplasm of the cell (inside the cell) - Example: Thyroid hormone ---\> goes through the cell, through the cytoplasm and into the nucleus to bind ---\> creates that reaction **Intracellular Receptors Steps** - In most cases ligand intracellular receptors are small, hydrophobic (water hating) molecules ---\> to cross plasma membrane and reach receptor - Intracellular responses are receptor proteins found inside the cell ---\> in cytoplasm (steroids) or nucleus (thyroid) 1. Ligand going to cross the plasma membrane (make sure you're small and hydrophobic) 2. Binds with intracellular receptor inside the cytoplasm 3. Goes directly into nucleus (thyroid) and binds to DNA, alters transcription of DNA within the cell - Causes changes very directly **Biomolecules**  - In the body, full of large molecules called Biomolecules - Different types that create living systems (us) - Biomolecules are polymers, which are repeating units of monomers - Polymer are formed when monomers are linked together to create a chain - Each polymer has its own type of monomer - Monomer - is a molecule with a low molecular weight that can combine with others of the same kind to form a chemical compound called a polymer - Example: - Bonds bind sugar monomers and create polymers (glycogen, starch or cellulose) - **Classes** - Polymers - Proteins - Carbohydrates - Lipids - Nucleic Acid - Monomers - Monosaccharide - Amino Acid - Nucleotides - Fatty Acid **Monomer - Amino Acids** - Monomer - is a molecule with a low molecular weight that can combine with others of the same kind to form a chemical compound called a polymer  - **Structure** - Basic amino group ---\> (-NH2) - Acidic carboxyl group ---\> (-COOH) - Organic R group ---\> side chain - Side chain important ---\> unique to each amino acid, varies depending on the type of amino acid ("side chics are all different types") - Every amino acid has its own particular structure, and own specific reactivity. It's the variation in that R group that determines the characteristic of the molecule that it forms when in a group of amino acids (groups of amino acids comes together to create these molecules) **Carbohydrates** - SUGAR (come from same class of molecules) - Name: hydrates with carbon - Carbohydrates are bi-molecules with 7 carbon atoms that each have a pair of hydrogen or hydroxyl group (a functional group with one hydrogen and one oxygen atom) - When they are small ---\> sugar (crose) - They're a group of organic compounds that occur in living tissues and foods in the form of starch, cellulose or sugars - Ratio of oxygen to hydrogen in carbohydrates is the same as water (2 to 1) - Carbohydrates typically broken down in the body to release energy - Simple Carbohydrates are classified based on the functional group found in the molecule **Classification of Carbohydrates**  - Simple Carbohydrates are classified based on the functional group found in the molecule - Example: ketose contains a ketone - Example: aldose contains aldehyde - Polysaccarides are organized by the number of sugar molecules in the chain (Saccaride ---\> sugar) - Poly, Di, or mono ---\> the number of sugars present within that molecule - Classification - Monosaccaride ---\> by number of carbons atoms they contain - building blocks for the monomers of all carbohydrates **Fisher Projections**  - a way to represent three-dimensional molecules in two dimensions on paper - It can depict complex carbs ---\> like glucose or fructose - Helps convey structural information - Horizontal lines represent atoms pointing towards the viewer (horizontal towards) - Vertical lines represent the atoms pointing (protecting) away from the viewer (vertical away) - Medication packets have fisher projection on them **Lewis Dot Structures** - Knowing the type of bonds formed between atoms utilizing valence electrons or/ and lone pairs and how many bonds an atom can or will form with other atoms. **Lipids** - A group of hydrophobic biomolecules (hates water) - Function - Protect, insulation and lubrication with primary function being long-term energy stores - Four groups - Triglycerides, phospholipids, steroids, waxes - All insoluble in water (fat in water) **Phospholipids**  - Similar to triglycerides in which they contain glycerol and 2 fatty acids - Phosphate group rather than a third fatty acid is attached to 3^rd^ carbon of glycerol (\#1) - They're important due to their unique properties, mostly in water - Phosphate's head in hydrophilic, and the tail is hydrophobic ("good hydration ---\> fat ass") - Molecule positions itself with the hydrophilic head that's going to interact with water, the hydrophobic tail hides from water - Phospholipids is a type of lipid molecule that's the main component of the cell membrane - **Each phospholipid is made up of** - **two fatty acids** - **a phosphate group - THIS IS WHAT STANDS OUT** - **glycerol molecule** - Form a double layer that's characteristic in all cell membranes (phospholipid bi-layer) - If phosphate group is removed, you will be left with a triglyceride (two fatty acids and a glycerol molecule) **Steroids** - Compounds of **4 fused rings of carbon**. - Cholesterol serves as a precursor for the synthesis of other steroids. - Present in plasma membrane where it stabilizes the membrane **Waxes** - Nonpolar and repel water - Found of outer surfaces of animals - Found in ears to protect from trauma - Wax is the wave!!! - **NOTES: Steroid are the 4 ring structure, wax is the wave (hydrocarbon tail), and hydroxyl group (OH) = makes cholesterol** **Fatty Acid** - Fats and oils  - Triglycerides and butter are solid in room temp - **Three parts** - Hydrocarbon chain - Acid group - Methyl group - **Types** - Saturated---\> have single bonds connecting the carbon molecules - Higher melting point - Unsaturated ---\> have double bonds connecting the carbon molecules - Effects melting point of that fat ---\> more likely to melt - Lower melting point because of double bond **[Triglycerides]**: - Glycerol head, 3-carbon alcohol, 3 fatty acids, **DNA and RNA** - **DNA** - Responsible for storing and transferring genetic information - Double stranded molecule that contains two antiparallel polynucleotide strands - Two strands joined with the HYDROGEN BONDS - Has Guanine and Cytosine as a pair ---\> Adenine and Thymine as a pair - G and C - A and T - DNA bonds with each other to make that double helix - Located In nucleus - Receipt box for the proteins - mRNA (messenger) going to transcribe that DNA and carry out messages to ribosomes, where protein synthesis is going to take place - tRNA (transfer) matches up with the messenger RNA (mRNA) and delivers amino acids the correct order of synthesis of the given protein - **RNA** - Directly codes for amino acids and as acts as a messenger between DNA and ribosomes to make proteins - Carries out genetic information that's translated by ribosomes into varies different proteins necessary for cellular processes - mRNA, tRNA, and rRNA ---\> protein synthesis - **Difference between DNA and RNA ---\> (DNA has Thymine) and (RNA has Uracil)** **Lecture 4 - Chemistry, Biochemistry, and Physics of Anesthesia** **Physics** - Study of how things work, fundamental law about how the world works around us - Anesthetic gasses - **Units** - Pressure ---\> kPa - Volume ---\> L - Temperature ---\> k (absolute zero) - Amount ---\> mols (Avogadro's number) - **Celsius to Fahrenheit** - Celsius = (F-32)/1.8 - Fahrenheit = (C \* 1.8) + 32 - **Kelvin** - 0 degrees kelvin is called the "ABSOLUTE ZERO" = -273 C or -459 F ---\> temp where there is no molecular activity or movement - No heat or energy lasts in a substance at this point - Kelvin = 273 + C - Celsius = K - 273 - **Measurements** - 1 kg = 2.2 lb - 1 inch = 2.54 cm - 1 atm = 760 mmhg/torr = 1bar= 100kPA= 14.7 psi---\> on sea level - At increased elevations ---\> atmospheric pressure (atm) goes down (submarine, when it goes down under water ---\> atmospheric pressure goes up) - 1 cubic meter (1m3) = 1 Liter - 1 centimeter cubed (1cm3) = 0.001 liters **Ideal (Universal) Gas Law** - Pressure, volume and temperature of an ideal gas are related by the following equation ---\> this what affects gases - Good approximation of the behavior of gases under many conditions - Anesthesia: when you have an e-cylinder and you release air from that compressed gas ---\> pressure inside the cylinder decreases - Each cylinder has a constant volume, when it is released ---\> pressure inside the cylinder decreases ---\> number of mols (gas) is decreasing (n) - **pV = nRT** - p = absolute pressure (atm) - V = volume (L) - n = number of moles of gas (mol) - R = universal gas constant - T = temperature in kelvin (K) \- Example: H2 has a volume of 8.56 L at 0C and 1.5atm. Calculate the moles of H2 present  - **Example:** - **Deflated Tire** - A. When air is pumped in deflated tire, its volume first increases without much increase in pressure - B. When the tire is filled to a certain point, the tire walls resist further expansion and the pressure increases with more air - C. Once the tire is inflated, its pressure increases with temperature **Newton's Laws** **1. Law of Inertia ---\> Object at rest or moving at a constant speed in a straight line tends to stay in motion unless acted upon by another force (" In the water")** - Example: - Splish Splash ---\> Tube going in straight line, the moment it hits the pool (another force) will cause the tube to stop ---\> external friction force of the water will effect the velocity of the tube **2. Law of Force ---\> Force is equal to mass x acceleration** - m = mass in kg - F = force - a = acceleration - Example - Light bowling ball ---\> you need less force to accelerate the bowling ball - Heavy bowling ball ---\> you need more force to accelerate the bowling ball, in order for it to be same speed as the lighter ball - Weight= mass x 9.8 - 9.8= speed of gravity - Mass stays the same anywhere in the universe - Weight can change because force of gravity changes (ex: earth and moon) **3. Law of Reciprocal Action ---\> for every action, there is an equal and opposite reaction** - Example - Pushing a stetcher ---\> you're pushing the stretcher, and you have the force of the stretcher pushing against you **Dalton's Law of Partial Pressure** - **In a mixture of gases, the total pressure exerted by the mixture is equal to the sum of the partial pressures of the individual gases, provided the gases DO NOT mix with each other** - **P~total~= P1 + P2 +...PN** - **The total pressure in a mixture of gases is equal to the sum of the pressures of the individual gases (each gas is said to exert partial pressure).** - **The partial pressure of a gas is calculated by multiplying the percent gas (fractional concentration) times the atmospheric pressure.** - **Anesthesia ---\> Allows us to calculate the percent of a gas if concentration percent is known**  - **In the atmosphere at sea level, the partial pressures are** - **O2 = 160 mm-Hg (21%)** - **N2 = 600 mm-Hg (79%)** - **Total = 760 mm-Hg (100%)** - **Volume % = [Partial pressure] X 100** - **Total Pressure** - **Examples:** **1. What are the partial pressures of N20 and O2 if they are delivered to the patient in a 70%/30% N20/02 mixture (assume sea level)?** - 70% x 760 mmHg = 532 mm-Hg for N20 (N20 can never be given to pt 100%) - 30% x 760 mmHg = 228 mm-Hg for O2 **2. What is the partial pressure of O2 in the mountains where the Patm is 550 mm-Hg?** - 21% x 550 mm-Hg = 116 mmHg **3. What is the partial pressure of CO2 if its concentration in the end-tidal gases is 5%?** - 5% x 760 mmHg = 38 mmHg **What are Vapor Pressures?** - Vapor pressure of a liquid is where an "equilibrium pressure" is reached inside a closed container ---\> where molecules go from gas to liquid or liquid to gaseous states in continuum, - Vapor Pressure is the function of ***[temperature]*** - **Boiling point of a liquid is the temperature at which the vapor pressure is equal to the atmospheric pressure** - **When at a higher altitude ---\> the boiling point goes down (you need less heat to boil a kettle at higher altitudes)** - **Since atmospheric pressure (atm) depends on altitude ---\> boiling point decreases at an increased altitude** - **With each 500 ft increase in elevation ---\> our boiling point is lowered by 1 degree Fahrenheit** - **Critical Temperature** - **The highest possible temperature value at which the substance can exist as a liquid** - The temperature at and above which the vapor of a substance can not liquify - Example: you boil water, you will reach a temperature where it turns into vapor, it doesn't matter what amount of pressure you put on it, once you went over that critical temperature ---\> it won't go back to a liquid - **Vapor Pressure is the Tendency of ALL of the liquid to turn into its gaseous form. That increases as temperature increases.** - Vapor pressure is a measure of the tendency of a ***[material]*** to change into the gaseous or vapor state, and **[it increases with temperature].** - The temperature at which the vapor pressure at the surface of a liquid becomes equal to the pressure exerted by the surroundings is called the boiling point of the liquid. - Every substance has its unique critical temperature above which it exists only as a gas, irrespective of how much pressure is applied to it. At or below this critical temperature, it can exist in both its liquid and gaseous forms; the latter is called a vapor - **Question: Is vapor pressure a function of temperature, volume, or pressure?** - **TEMPERATURE** - **Saturated Vapor Pressure** - **Function of temperature** - **At any given temperature, at any given altitude, at a point where the dynamic equilibrium will occur. The number of molecules leaving the liquid phase is equal to the number reentering it ---\> saturated vapor pressure** - **Pressure that the vapor exerts ---\> equal to leaving and entering** - Saturated VP is the ***[pressure]*** at which the gaseous state is in equilibrium with either the liquid state, solid state, or both. - The boiling point of a liquid is the temperature at which the saturated vapor pressure is equal to the atmospheric pressure- essentially the boiling point of a liquid is dependent on the atmospheric pressure. - Since atmospheric pressure depends on altitude, the boiling point is depressed as altitude increases. - **Evaporation** - Occurs only ***[at the surface]*** of a ***[liquid]*** requires heat energy ---\> the latent heat of vaporization - This can be increases by having the vapor in a closed container ---\> like the vaporizer - Example: when you boil water, the water from the top starts becoming vapor **Dalton's Law in Practice** - The pressure exerted by an individual gas in a mixture is known as its partial pressure - Assuming we have a mixture of ideal gases, we can use the ideal gas law to solve problems involving gases in a mixture - Dalton's law of partial pressure states that the total pressure of a mixture of gases is equal to the sum of partial pressures of the component gases. Gas1+gas2+Gas3 = Total Gas. - NOTE: We don't want to give patient so much oxygen ---\> free radicals ---\> o2 toxicity - **Volatile Agents in a flask** - Example: The vapor pressure is added to a flask of oxygen, what is the percent oxygen and percent of O2 after the Isoflurane is added is (760 -- 240 mm Hg) = 520 mm-Hg. - \% O2 = [520mmHg] x 100% = 68.4% - \% Isoflurane = [240 mmHg] x 100% = 31.6% 760 mmHg **Pressure and Tension** - Measure high pressure ---\> cylinder pressures - Measures pressure relative to atmospheric pressure (not absolute pressure - no matter inside of the space, a p - **When gauge pressure reads zero, its reading atmospheric pressure (atm) ---\> 760 mmHg (zero is reading the atmosphere's pressure)** - These are mechanical pressure instruments **Law of Laplace** - **Cylindrically-Shaped Structures** - Law of Laplace states that for a cylindrically shaped structure with an infinitely thin wall, as a structure expands (the radius increases), the tension (force) in the all of the structure increases - **T = P x r** - **T = wall tension** - **P = pressure of liquid within a cylinder** - **r = radius** - **[T]**he **[P]**erfect **[R]**adius lives in **la place** - **Example** - Blood Vessels ---\> wall tension is proportional to the radius. A larger radius, the higher the tension, the more likely the vessel will rupture - Aortic aneurysm ---\> more likely to rupture because the radius is larger, you increase the tension of the wall to the breaking point - Capillaries ---\> smaller than a vein, because it has a tiny radius compared to a vein, the tension in the wall is much smaller, so it's less likely to rupture because it can withstand a higher pressure - Left Ventricle ---\> the greater filling of the left ventricle, the greater the tension in the ventricular wall. FRANK STARLING. - When filling is increased ---\> ventricular wall tension increases - Since it has more thickness ---\> la place modifies for the thickness - Side Note: Greater tension in the ventricle wall at the end diastole, the greater the SV ---\> Frank Starlings - - - - **Spheres** - **Tension = [pressure x radius ]** - **→ its like an S for spheres but backwards** -  - **Shows how smaller alveoli are more prone to collapse (as their radius decreases, the pressure needed to keep them open increases)** - Surfactant reduces alveolar surface tension and prevents alveolar collapse - Radius of the alveoli changes and distribution of the surfactant ---\> surface tension remains constant because of that surfactant and prevents small alveoli from collapsing - Smaller - Example - Babies first breath, they create large negative intrathoracic pressure ---\> opens alveoli with surfactant ---\> surface tension goes away **Hagen-Poiseuille Law of Physics** - **Q= Flow** - **R= radius of cross section of the tube** - **P= pressure** - **𝜂= Viscosity of gas or liquid** - **L= length of the tube** - Changing radius has the most dramatic effect on flow. - If you double the radius ---\> flow multiplied by 16 - THE SURGEON ALERTS YOU HE ACCIDENTALLY RUPTURED AN ARTERY. YOU HANG BLOOD AND NEED TO INFUSE THAT RAPIDLY, WHAT DO YOU DO? - Put a large bore angiocath into your patient - Increase the height of the IV pole - Use a rapid infuser / pressure bag - Heat the blood to increase flow (hot blood runs faster)  **Reynold's Number** - Helps predict the flow patterns in different fluids or gas law situations - At low Reynold's numbers the flow is dominated by laminar or straight flow - High Reynold's number (greater than 4000) is dominated by turbulent flow - Laminar flow is dependent on gas viscosity (LV) → related to Poiseuille (viscosity) - Turbulent flow is dependent on gas density (TD) → related to Grahams (density, this law states that the lower the density of a gas, the higher the diffusion) - **Flow Becomes Turbulent if** - Velocity of flow if high - Tube wall is rough (corrugated) - There are kinks, bends, narrowing in the tube - RAE Tube - flow is turbulent at the angle (bend) - Resistance to flow increases when flow becomes turbulent, ventilating patients is more difficult when flow is turbulent **Venturi, Bernoulli and Coanda Effect** - **Bernoulli's Principle**  - Relationship between pressure and velocity of a gas or fluid moving through an area of constriction - Moving through wide tube ---\> hits the narrow portion ---\> causes the velocity of the fluid to increase (constriction and then flies) - **Venturi's Effect** - Air flow is large and slow ---\> passes through area of narrowing and the hole ---\> entrains the air inside the area - **Coanda Effect** - Airflow follows the curve (a spoon in water) or continues to one of the two deviations **Henry's Law** - At a ***constant temperature***, the amount of gas dissolved in a solution is directly proportional to the partial pressure of gas over the solution - Increased pressure = increased gas solubility (the more it will dissolves into a liquid) - S (solubility) = Kh (Constant) x P (pressure) - CO2 is 20x more soluble than O2 - Oxygen = 0.003 ml/dL/mmHg - Carbon dioxide = 0.067 ml/dL/mmHg - Examples: - - 1.5 - 0.3 = [1.2 mL O2/100mL blood ] **3. How much O2 is dissolved if FiO2 is 40%?** - If the inspired O2 is given, estimate the PaO2 by multiplying the inspired concentration by 5 40 x 5 = 200mmHg (estimated PaO2) 200mmHg x 0.003 = 0.6 mL O2/100mL blood - **How much CO2 is dissolved** 200mHg x 0.067 = 13.4 mL CO2/100mL blood **4. How much CO2 is dissolved in arterial blood when PaCO2 is 50mmHg?** 50mmhg x 0.067 = 3.35 mL CO2/100mL blood  **Boyle's Law** - At constant temperature, volume of a given mass of gas is inversely proportional to absolute pressure (TB ---\> Temperature constant in Boyle's) - Decreased pressure = increased gas volume - Pressurized cylinder opened slowly (so temp doesn't change), gas released from the cylinder can be estimated by Boyle's Law. The gas is decreased, and the pressure is increased - **Volume increases = Pressure decreases** - **Example: Gas \#1 ---\> 12.3 L, 40.0mmHg pressure** **Gas \#2 ---\> 60 mmHg pressure** **(40mmHg)(12.3L) = (60mmHg)V2** **[V2 = 8.2 L]** **So if we use 3 L of O2 ---\> E type full cylinder will last about 2.7 minutes** - **Clinical application** - Squeezing an ambu bag raises the pressure and decreases the volume - During inspiration when breathing spontaneously, intrapulmonary pressure falls and volume increases - During expiration, intrapulmonary pressure increases and volume decreases - Measurement of FRC body plethysmography uses Boyle's Law **Charles Law** - At a constant pressure, volume of gas is directly proportional to the temperature  - Constant pressure, volume goes up and temp goes up (CP ---\> pressure constant in Charles) - **Clinical Application** - placed into an autoclave for sterilization, temperature increases and volume increases too - If you keep an LMA with cuff pressure, temperature builds ---\> it expands - One way heat lost from the body is that the air next to the the body warms up and rises and from this process, more heat is lost from our patients as they continue to lose heat (important for pediatric patients) **Gay Lussac's Law** - **At constant volume, the absolute pressure of the given mass of gas is directly proportional to the temperature (Gay Valentine ---\> Constant volume in Gay's)** - **Clinical Application** - **Medical gases are stored in cylinders having a constant volume and high pressure (138 Barr in a full O2 / Air cylinder). If these are stored at high temperatures, pressures will rise causing explosions** - **As a N2O cylinder empties, the pressure in the tank decreases even when N2O liquid is present.** - **The Joule-Thompson effect explains the decrease in pressure, as temperature decreases in a constant-volume cylinder = the pressure of the gas in the cylinder decreases (JOULES IS COOL ---\> decreased pressure = decreased temperature)**  **Avogadro's Number and Hypothesis** - States that equal volumes of all gases at the same temperature and pressure contain equal numbers of particles - Avogadro's number ---\> the number of molecules in one mole of a substance is 6.022 X 1023 - Avogadro\'s hypothesis: one mole of a gas at standard temperature (273 K) and standard pressure (1 atm) occupies a volume of 22.4 liters - **Example:** - **Two moles of gaseous N20 occupy what volume under standard conditions? Under standard conditions, two moles of gaseous N20 occupy?** **22.4 x 2 = 44.8 L** - The law can also be defined as one gram molecule weight (one mole) of a gas contains 6.022X1023 - (Avogadro's number) molecules = occupies 22.4L at STP. - PV = n RT is the ideal gas equation - R is the universal gas constant = 1.987 J/degree/mole in SI units - **Clinical Application** - Since the cylinder volume is constant, temperature is constant and R is already a constant P = N - Pressure shown in the Bourdon's gauge is proportional to the number of molecules which is the amount of gas in the cylinder - Hence the pressure gauge acts as a content gauge **Cylinders** - **Critical Temperature** - The highest temperature where a gas can exist as a liquid, and is also the temperature where a gas can not be liquefied regardless of the pressure applied to it above this temperature - **Adiabatic Processes (Constant Heat)** - If a cylinder of compressed gas is opened into a closed space (of pipes) the pressure in the closed space will rise rapidly and the temperature will also rise rapidly, possibly to levels that can ignite a flame. This process occurs without gain or loss of energy (heat) - When you increase pressure ---\> increased temperature - **Joule-Thompson Effect) JOULE IS COOL** - When a compressed gas is allowed to escape freely into space, the process is adiabatic and cooling occurs. - Example: release air from tank ---\> causes decreased temperature - When you decrease pressure ---\> decrease in temp **Nitrous Oxide Cylinder (N20)** - Can't tell how much gas is there based on gauge - As gas escapes from nitrous oxide cylinder, the liquid N20 in the cylinder evaporates. Heat is lost from this liquid vaporization (latent heat of vaporization) and temp in cylinder falls (Joules) - As temperature falls ---\> pressure is also decreased - Full tank of N20 has a PSI of 745 until 1/4 of tank left. At 1/4 or 400 L, you will see drop in pressure - To check how much is left in tank ---\> weight it - **Full tank of N20 = 5.6kg** - **We cannot use N2O cylinders pressure gauges in the same way we use O2 pressure gauges. N20 contains both vapor and liquid so these law do not apply** - **How do anesthesia providers calculate the quantity of N20?** - N2O is stored in cylinders as a liquid - Exists partly as liquid and partly as a gas - Through known cylinder weight and measured weight amount of N2O and usage is calculated using Avogadro's hypothesis. - N20 - PSI → 450 - Liters → 1590 **Calculation of N20** - **Weight of full N20 Cylinder ---\> 5.6kg** - **Tare Weight (empty weight) ---\> 4.5kg** - **Weight of N20 ---\> 1.1 kg (weight of N2O in this problem- subtract full cylinder weight by tare weight)** 1.1 kg of N20 = [22.4L x 1100g] = 560L [ 560L] = 280 minutes 44g 2L/min 1.1 kg= 1100g 22.4L= volume at standard temp and pressure 44g= molecular weight of N2O If we administer 2 liters of N20/min, the cylinder will provide gas for 280 minutes or 4.6 hours.  **Oxygen Cylinder** - You can't liquify oxygen no matter how much pressure or compression you put on it - PSI ---\> 1900-2200 (know 2000) - Liters ---\> 660 L - NOTE: The Pin Index Safety System ---\> The blue pins are located where you hook a cylinder up, it's a safety check to make sure you're not hooking up the wrong gas  **D= fourth letter of the alphabet so multiple by 4 = 0.16** **E= 0.28** **G = (kinda like the number of H&K but minus 1 and decimals rearranged) 2.41 lol** **H&K = 3.14 = pi** **DURATION (min) = (Cylinder Pressure) x (Cylinder Factor)** **---\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--** **(Gas Flow)** Practice questions An E size oxygen cylinder with 2000 psig in it is being used at 4 L/min. How much will be used in 45 minutes? An H size oxygen cylinder, with 1450 psig, is being used at 5L/min. This cylinder will be empty in:  The cylinder at a patient\'s beside contains 1300 psig and is using 7L/min. How long will it take to use 800 psig? The E cylinder on a crash cart contains 900 psig. How long would the cylinder last if used at 10L/min?  An H size cylinder, with 2000 psig, is used for 6 hours at 5L/min. How much gas was used during this time?