This document provides information about Boyle's anesthesia machine. It discusses the components and functions of an anesthesia machine, including the pneumatic and electrical systems. It describes the different parts of the machine like the flowmeters, vaporizers, check valves, and safety features. The document explains how flowmeters work using the Hagen-Poiseuille equation and factors like viscosity, density, and laminar vs turbulent flow. It discusses temperature and pressure effects on flowmeters as well as protections against delivering a hypoxic gas mixture to the patient.
Neuromuscular monitoring, also known as train of four monitoring, is a technique used during recovery from the application of general anesthesia to objectively determine how well a patient's muscles are able to function. It involves the application of electrical stimulation to nerves and recording of muscle response using, for example, an acceleromyograph. Neuromuscular monitoring is typically used when neuromuscular-blocking drugs have been part of the general anesthesia and the doctor wishes to avoid postoperative residual curarization (PORC) in the patient, that is, the residual paralysis of muscles stemming from these drugs.
mapleson circuits used in anesthesia practice, are in their way out but it is as important to know the mechanism with which the gases flow to and fro through them.
The transversus abdominis plane, more commonly referred to as the TAP block,
Places local anesthetic in the lateral abdominal wall in a plane between the internal oblique and the transversus abdominis muscles.
Here, the local anesthetic block can block many of the abdominal nerves as they pass to the abdominal structures.
anaesthesia Breathing circuits and its classification and functional analysisprateek gupta
anaesthesia breathing circuits. mapleson circuits. classification of circuits. functional analysia of circuits. draw over circuit. advantages and disadvantages of different circuits.
Neuromuscular monitoring, also known as train of four monitoring, is a technique used during recovery from the application of general anesthesia to objectively determine how well a patient's muscles are able to function. It involves the application of electrical stimulation to nerves and recording of muscle response using, for example, an acceleromyograph. Neuromuscular monitoring is typically used when neuromuscular-blocking drugs have been part of the general anesthesia and the doctor wishes to avoid postoperative residual curarization (PORC) in the patient, that is, the residual paralysis of muscles stemming from these drugs.
mapleson circuits used in anesthesia practice, are in their way out but it is as important to know the mechanism with which the gases flow to and fro through them.
The transversus abdominis plane, more commonly referred to as the TAP block,
Places local anesthetic in the lateral abdominal wall in a plane between the internal oblique and the transversus abdominis muscles.
Here, the local anesthetic block can block many of the abdominal nerves as they pass to the abdominal structures.
anaesthesia Breathing circuits and its classification and functional analysisprateek gupta
anaesthesia breathing circuits. mapleson circuits. classification of circuits. functional analysia of circuits. draw over circuit. advantages and disadvantages of different circuits.
This article provides a brief yet concise idea about flow meters and the pertinent terms related to them. This article classifies the different types of flowmeters and cites the different devices for measurement under these categories. Also, this article speaks about the major five classes of flowmeters viz. differential pressure, velocity, positive displacement, mass, and open channel.
Rev. August 2014 ME495 - Pipe Flow Characteristics… Page .docxjoyjonna282
Rev. August 2014 ME495 - Pipe Flow Characteristics… Page 2
2
ME495—Thermo Fluids Laboratory
~~~~~~~~~~~~~~
PIPE FLOW CHARACTERISTICS
AND PRESSURE TRANSDUCER
CALIBRATION
~~~~~~~~~~~~~~
PREPARED BY: GROUP LEADER’S NAME
LAB PARTNERS: NAME
NAME
NAME
TIME/DATE OF EXPERIMENT: TIME , DATE
~~~~~~~~~~~~~~
OBJECTIVE— The objectives of this experiment are
to: a) observe the characteristics of flow in a pipe,
b) evaluate the flow rate in a pipe using velocity
and pressure difference measurements, and c)
perform the calibration of a pressure transducer.
Upon completing this experiment you should have
learned (i) how to measure the flow rate and average
velocity in a pipe using a Pitot tube and/or a resistance
flow meter, and (ii) how to classify the general
characteristics of a pipe flow.
Nomenclature
a = speed of sound, m/s
A = area, m
2
C = discharge coefficient, dimensionless
d = pipe diameter, m
d0 = orifice diameter, m
E = velocity approach factor, dimensionless
f = Darcy friction factor, dimensionless
K0 = flow coefficient, dimensionless
k = ratio of specific heats (cp/cv), dimensionless
L = length of pipe, m
M = Mach number, dimensionless
p = pressure, Pa
p0 = stagnation pressure, Pa
p1, p2 = pressure at two axial locations along a
pipe, Pa
Q = volumetric flow rate, m
3
/s
R = specific gas constant, J·kg/K
Re = Reynolds number, dimensionless
T = temperature, K
V = local velocity, m/s
V = average velocity, m/s
Y = adiabatic expansion factor, dimensionless
= ratio of orifice diameter to pipe diameter,
dimensionless
p = pressure drop across an orifice meter, Pa
= dynamic viscosity, Pa·s
= air density, kg/m3
INTRODUCTION— The flow of a fluid (liquid or
gas) through pipes or ducts is a common part of many
engineering systems. Household applications include
the flow of water in copper pipes, the flow of natural
gas in steel pipes, and the flow of heated air through
metal ducts of rectangular cross-section in a forced-air
furnace system. Industrial applications range from the
flow of liquid plastics in a manufacturing plant, to the
flow of yogurt in a food-processing plant. Because the
purpose of a piping system is to transport a desired
quantity of fluid, it is important to understand the
various methods of measuring the flow rate.
In order to work with a fluid system, and certainly to
design a fluid system that will deliver a prescribed
flow, it is necessary to understand certain fundamental
aspects of the fluid flow. For this, one should be able
to answer questions like: Are compressibility effects
important? Is the flow laminar or turbulent? Is the
viscosity of the fluid important or not? Is the flow
steady or varying with time? What are the primary
forces of importance? For internal ...
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
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Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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Low pressure system in anaesthesia machine
1. Dr. Swadheen kumar Rout
1st year P.G
Dept. of Anaesthesiology
M.K.C.G College & hospital
2. Anaesthesia machine:- Function is to deliver a precisely-known but
variable gas mixture, including anesthetizing
and life-sustaining gases at a controlled &
known pressure.
Types
Intermittent( gas flows only during inspiration)
Ex. – Entonox apparatus
Continuous(Gas flows both during
inspiration and expiration)
Ex.- Boyle`s machine ,.
3. Boyle`s anaesthetic machine is a continuous-flow type
machine used for administration of anaesthetic gases.
was pioneered by Henry Gaskin Boyle (1875-1941).
the original machine from 1917 was carried around in a
wooden box and used ether and nitrous oxide.
It has undergone various modifications with time to increase its
safety & utility.
4. SYSTEM COMPONENTS
ELECTRICAL SYSTEM PNEUMATIC SYSTEM
- Master switch
- Battery back up
- Battery recharge
- Electric outlet for in built monitor
- Circuit breaker
- High pressure system
- Intermediate pressure system
- Low pressure system
5. Extends from the flow control valves to the common gas
outlet.
Consists of : - Flowmeters
- Hypoxia prevention safety devices
- Unidirectional check valve
- Pressure relief valves
- Common gas outlet
- Vaporiser & their mounting devices
6. TUBE: made of glass (THORPE tube).
Tubes are contained in a chromium plated
metal casing protected by a plastic
window.Backplate is luminous & detachable.
Anti-static coating.
INDICATOR: Float / Bobbin made usually of
aluminium.
It is free moving device & must not stick to
tube wall.
If it moves erratically, readings may be
inaccurate.
TYPES Non-rotating H type
Rotating type
Slanted grooves
Ball type
STOP: Prevents float from plugging the outlet &
prevents rising to a point it cannot be seen.
7. Types of flowmeters
1. Variable orifice flowmeters (fixed pressure difference)
2. Fixed orifice flowmeters (variable pressure difference)
• The area between the outside of the bobbin and the inside of the tapered glass
tube represents a orifice / annulus. It can be considered an equivalent to a
circular channel of the same cross-sectional area
Variable orifice flowmeters type used mostly today in modern machines.
(Synonym- Rotameters)
• The glass tube, slightly smaller on
cross-section at bottom than at top (tapered tube)
•Can be single or double taper.
Single taper have gradual increase in diameter from bottom
to top, used when there are different tubes for high & low flows.
Dual taper have two different taper inside the same tube .one for
fine flows (200mL/min to 1L/min) & one for coarse flows.
-used when only one tube is used for a gas.
10. Flowmeters adjust the proportions of medical gases controlled by the
anesthesia machine as well as the total gas flows delivered to the patient
circuit .
Flowmeters measure the drop in pressure that occurs when a gas passes
through a resistance and correlates this pressure drop to flow .
When the flow control valve is opened the gas enters at the bottom and
flows up the tube elevating the indicator.
The indicator floats freely at a point where the downward
force on it (gravity) equals the upward force caused by gas
molecules hitting the bottom of the float.
As the bobbin rises with increased flow, the size of the annulus between it
and the glass tube increases. In other words, there is a variable orifice
around the bobbin which depends on the gas flow.
11. As the bobbin rises from
A to B, the
clearance(annulus)
increases (from X toY)
12. Laminar flow-
Flow (Q) through a tube is laminar.
In order to drive fluid through a tube, a pressure difference (P = P1-P2)
must be present across the ends
• There is a linear relationship so that flow is directly
proportional to pressure under conditions of laminar
flow (Q@P)
• Reducing the diameter (d) in half reduces the flow
to 1/16 of its original value if the pressure drop along
the tube remains the same, i.e. flow is proportional to
the 4th power of the diameter (Q@d4)
• Reducing the length by half, doubles the flow
(Q@1/L)
13. Summary: Q @ P Q = flow through tube
Q @ D4 P = pressure across tube
Q @1/L D = diameter of tube
Q @1/n L = length of tube
n= viscosity of fluid
All these factors are incorporated in the Hagen-Poiseuille equation:
• Viscosity (n) of fluid affects resistance to laminar flow such that the higher the
viscosity, the slower the flow (Q@1/n)
Substituting radius (r)
for diameter
14. Turbulent flow is often present where there is an orifice, a sharp bend or
some other irregularity which may cause local increase in velocity.
Turbulence is also affected by other factors such as viscosity and density
of the fluid and diameter of the tube.
The effect of density on onset of turbulent flow can be illustrated by use of
helium in respiratory disorders
Helium reduces the density of the gas inhaled and so reduces the incidence
of turbulent flow, therefore lower resistance to breathing
These factors combine to give an index called Reynolds number
V = linear velocity of fluid
P = density
D = diameter of tube
U = viscosity
• Reynolds number > 2000 means turbulent flow likely
• Reynolds number < 2000 means flow likely to be laminar
• For a fixed set of conditions, there is a critical velocity at which Reynolds number has
the value of 2000
When the velocity exceeds this critical value, flow is likely to change from
laminar to turbulent .
15. As the bobbin rises
increase in the area of the annular orifice
flow resistance decreases
flow rate increase
The rate of flow through the flowmeter tube depends on:
- Pressure drop across the constriction
Weight Of Float/Cross-sectional Area
- Size of annular orifice
- Physical properties of the gas
16. At low flows:
- gas flow around the bobbin approximates to tubular flow (diameter
of channel less than length)
- gas flow is laminar so viscosity is important
At high flows:
- gas is flowing around the bobbin through an orifice (diameter of
channel greater than length)
- gas flow is turbulent so density is important
Tube = Length >
Diameter
Orifice = Diameter >
Length
17. Flowmeter are calibrated in litres per min. For <1 L/min
expressed in ml or decimal fractions of a litre per minute with a
zero before the decimal point.
Are calibrated at atmospheric pressure
(760 torr) and room temperature(200C) based
on physical properties of individual gases.
Changes in temperature & pressure affect
density & viscosity of gas and affect flowmeter
accuracy.
As flow changes from laminar to turbulent within
the flowmeter the flow changes from being directly
proportional to pressure to proportional to the
square root of pressure and hence the graduations
on the flowmeters are not uniform.
18. There may be one or two rotameters for each gas
Single flowmeter layout is the safest but less precise for low flows.
If two are present for any gas, the first permits accurate
measurement of low flows (usually up to 1 L/min) and the other, of
flows up to 10-12 L/min
Flow indicator tubes for different gases are grouped side by side
The various gas flows meet at the common manifold (mixing
chamber) at the top . In such a case, the tubes may be arranged
either in parallel or in series
19. Parallel arrangement:
•Two complete flow indicator assemblies with a flow control valve for each
assembly
•The total flow of the gas to the common manifold is the sum of the flows on
both flow indicators
•Not presently available because accidental use of low-flow oxygen flow
indicator when a high flow is intended is a hazard whenever two oxygen
flow control knobs are present
Series (tandem) arrangement:
• One flow control valve for the two flow indicator tubes
• Gas from the flow control valve first passes through a tube calibrated up to 1
liter per minute, then passes to a second tube that is calibrated for higher flows
• Total flow is not the sum of the two tubes but that shown in the higher flow
tube.Tandem flow tubes increase accuracy at all flow rates
20. The O2 flowmeter is positioned on the right side (most distally) of
the rotameter bank, downstream from the other flowmeters and
closest to the common gas outlet
In the event of a leak in one of the other flowmeter tubes, this
position is the one least likely to result in a hypoxic mixture.
In A and B a hypoxic mixture can
result because a substantial portion of
oxygen flow passes through the leak,
and all nitrous oxide is directed to the
common gas outlet.
C and D, The safest configuration
exists when oxygen is located in the
downstream position
21. However a leak in the oxygen flowmeter tube can cause a
hypoxic mixture, even when oxygen is located in the
downstream position.
22. Temperature and Pressure Effects
Changes in temperature and pressure alter both viscosity and
density of gases, thereby affecting accuracy of the indicator on the
flowmeters.
Temperature effects are slight and do not cause significant changes
At high altitude, barometric pressure decreases resulting in
increased flow.
At low flow rates, flow is laminar and dependent on gas viscosity, a
property not affected by altitude.
At high flow rates flow becomes turbulent, and flow becomes a
function of density, a property that is influenced by altitude.
The resulting decreases in density will increase the actual flow rate
so the flowmeter will read lower than the actual flow rate.
At increased pressure, as in a hyperbaric chamber, the reverse is
seen; the delivered flow rate is slightly less than the actual flow rate.
23. Back Pressure:
In machines without an outlet check valve, if pressure at the common
gas outlet increases, this is transmitted back to the flowmeters,
compressing the gas above the float
Pressure above the indicator rises forcing the float down, causing the
flowmeter to be read lower than the actual gas flow rate
Static Electricity:
Static electricity causes the float to stick to the side of the tube causing
reading inaccuracy.These electrostatic charges are negligible as long as
the float rotates freely
Hidden Floats:
The float may adhere to the stop at the top of the tube even if no gas
is flowing
The float may disappear from view if there is no stop present e.g.
broken float stop
24. Protection against hypoxic mixture at the flowmeter level.
Prevention of delivery of a hypoxic gas mixture is a major
consideration in the design of contemporary anesthesia machines.
Mandotary minimum oxygen flow: Some machines require a
minimum flow (50-250ml/min) of oxygen before other gas will flow.
Some machine activate an alarm if O2 flow falls below a certain limit.
Minimum oxygen ratio:
In modern anesthesia machines, N2O and O2 flow controls are
physically interlinked so that a fresh gas mixture containing at least
25% O2 is delivered at the flowmeters when only N2O and O2 are
used .
Ohmeda = mechanical + pneumatic interlink (Link–25)
North American Dräger = pneumatic interlink
25. A 14-tooth sprocket is
attached to the N2O flow
control valve, and a 28-tooth
sprocket is attached to the O2
flow control valve. A chain
mechanically links the
sprockets.
For every 2 revolutions of the
N2O flow control spindle, an
O2 flow control, set to the
lowest O2 flow, rotates once
because of the 14:28 ratio of
the gear teeth.
26. Regardless, of the O2 flow set, if the flow of N2O is increased >75%,
the gear on O2 spindle will engage automatically with the O2 flow
control knob causing it to rotate and thereby causing O2 flow to
increase to maintain O2 Conc of 25% with a maximum N2O:O2 ratio
of 3:1.
If attempt is made to increase N2O flow beyond that ratio, O2 flow is
automatically increased & if O2 flow is lowered too much N2O flow
reduces proportionately. The final 3:1 flow ratio results because the
N2O flow control valve is supplied by
approximately 26 psig, whereas the O2 flow
control valve is supplied by 14 psig. Thus, the
combination of the mechanical and pneumatic
aspects of the system yields the final oxygen
concentration.
27. It is a pneumatic O2-N2O interlock system designed to maintain a
fresh gas oxygen concentration of at least 25% .
The ORMC limits N2O flow to prevent delivery of a hypoxic mixture,
unlike the Ohmeda Link-25, which actively increases O2 flow .
composed of an O2 chamber, a N20 chamber, & a N20 slave control valve; all
are interconnected by a mobile horizontal shaft. The pneumatic input into the
device is from the O2 & N20 flowmeters.
These flowmeters have specific resistors located downstream from the flow
control valves which create back pressures directed to the O2 & N2O chambers.
The value of the O2 flowtube resistor is three to four times that of the N2O
flowtube resistor..
The back pressure in the O2 & N2O chambers pushes against rubber
diaphragms attached to the mobile horizontal shaft. Movement of the shaft
regulates the N2O slave control valve, which feeds the N20 flow control valve.
28. The back pressure exerted on the O2 diaphragm, in the upper configuration, is greater
than that exerted on the N2O diaphragm. This causes the horizontal shaft to move to the
left, opening the N2O slave control valve. N2O is then able to proceed to its flow control
valve and out through the flowmeter.
In the bottom configuration, the N2O slave control valve is closed because of
inadequate O2 back pressure
29. The ORMC also rings alarms (it has an electronic component)
to prevent a hypoxic mixture delivery .
Dräger S-ORC (sensitive oxygen ratio controller), newest
hypoxic guard system as found on Fabius GS guarantees a
minimum FIO2 of 23%. Its fail-safe component shuts off nitrous
oxide if the oxygen flow is less than 200 mL/min, or if the
oxygen fresh gas valve is closed.
30. Machines equipped with proportioning systems can still deliver
a hypoxic mixture under the following conditions
Wrong Supply Gas in oxygen pipeline or cylinder.
Defective pneumatic or mechanical components.
Leaks exist downstream of flow control valves.
Inert gas administration( He,CO2) : Proportioning systems
generally link only N2O and O2.
Use of an oxygen analyzer is mandatory if the operator uses a
third inert gas.
31. Present on some machines (Ohmeda)
between the vaporizers and common
gas outlet, upstream of where oxygen
flush flow joins the fresh gas flow .
Positive pressure ventilation & use of O2
flush cause back flow of the gas.
This back flow can cause “pumping
effect”, if not prevented, could cause
increased vaporizer output
concentrations.
• Pressure increase can also increase leaks and cause inaccurate flow
indicator readings.
32. The purpose of the outlet check valve, where present, is to
prevent reverse gas flow,
Newer machines (North American Dräger) are equipped with
vaporizers that incorporate a baffle system and specially
designed manifold to prevent pumping effect, making an outlet
check valve unnecessary.
*Important: Testing the breathing
system for leaks will not detect a leak
in the machine equipped with a check
valve
33. Situated on the back bar of the machine
downstream of voporizers or near
common gas outlet.
Prevents high pressure from transmitted
in to machine & from machine to patient.
When preset pressure is exceeded valve
opens & gas is vented outside.
Usually opens when pressure in the
back bar exceeds 35 Kpa.
34. Located in between flowmeter device and common gas outlet.
Permanent mounting.
Vapourizers and flowmeters are connected to each other and
then bolted with back bar.
35. Receives all gases & vapors from the machine & delivers the
mixture to the breathing system.
Outlet in most of the machines have 15 mm female slip-joint
connection, with coaxial 22 mm male connection•
Machine standards mandates that it be difficult to accidentaly
dis-engage the delivery hose from the outlet.
The pressure delivered at outlet is 5-8 psi.
Editor's Notes
sthesia workstation Components: anesthesia machine, vaporizers ventilator breathing system scavenging system Monitors suction equipment data management system
ELECTRICAL PNEUMATIC
Callibarated for gas at atmospheric pressure & 20 Cnon-rotating HBall type
AS GAS FLOWS AROUND INDICATIOR,IT ENCOUNTERS A FRICTIONAL RESISTANCE BETN THE WALL OF TUBE & INDICATOR ,,THER IS LOSS OF ENERGY REPRESENTED AS A PRESSURE DROP
There may be one or two rotameters for each gas If two are present for any gas, the first permits accurate measurement of low flows (usually up to 1 L/min) and the other, of flows up to 10-12 L/min Flow indicator tubes for different gases are grouped side by side The various gas flows meet at the common manifold (mixing chamber) at the top In such a case, the tubes may be arranged either in parallel or in series
Broad terminology for hypoxic guard systems. prevent final inspired oxygen concentration less than 0.25
An alarm is activated when the ORMC is functioning to prevent a hypoxic mixture when the DrägerNarkomed machine is used in the “N2O/O2” mode