Very Important equations about ventilators, anesthesia and the principles of them for BMEE students
Q1. What organ regulates breathing and how?
The brain regulates breathing and does this automatically.
Q2. Describe the steps through which oxygen passes to produce energy.
Oxygen enters the lungs and moves into the bloodstream, which carries it to the vital organs and tissues to oxygenate them and to produce energy.
Q3. What does ventilation mean?
The movement of gas into and out of the lungs is called ventilation.
Q1. What are the elements of the conductive airways?
The conductive airways consist of the nose, pharynx, larynx, trachea, bronchi and bronchioles.
Q2. What is the role of the epiglottis?
The epiglottis is a switch between the trachea and the esophagus. A closed epiglottis leads food into the esophagus, an open epiglottis allows air to enter the lungs.
Q3. Name the inspiratory muscles.
The inspiratory muscles are the diaphragm and the external intercostal muscles.
Q4. What is diffusion?
Spontaneous movement of molecules from a region of higher concentration (pressure) to a region of lower concentration (pressure).
Q5. What is perfusion ?
Perfusion is the flow of fluid (blood) through a vessel.
Q6. What are the two phases of respiration that must precede oxygen entering the blood?
Ventilation and diffusion are the two phases of respiration that precede the entering of oxygen into the blood.
Q7. What does “ anatomical dead space” mean?
Air volume in airways that does not participate in the gas exchange.
Q8. How much of the total lung capacity does the tidal volume take up?
Tidal volume normally takes up 10 % of the total lung capacity.
Q9. How much of the tidal volume does alveolar ventilation take up?
Alveolar ventilation takes up 70 % of the tidal volume.
Q10. How much is the moisture loss during normal breathing?
The moisture loss is normally 7 mg/l.
Q1. What are the main tasks of circulation?
The two main tasks of circulation are to carry oxygen to cells and carbon dioxide to the lungs.
Q2. Name the three elements of the circulatory system. What are their functions?
The circulatory system consists of the systemic circulation that transports oxygenated blood from the heart to organs and tissues and back to the heart; the pulmonary circulation that transports deoxygenated blood from the heart to the lungs to be oxygenated and returns it to the heart; and the coronary circulation that delivers blood to the heart muscle itself.
Q3. Add the names of the various parts of the heart to the diagram below.
[LEFT] Q4. What does ECG stand for and what does it record?Electrocardiogram, a recording of the changes of electrical potential occurring during heartbeat.Q5. What is the heart muscle called?The heart muscle is called the myocardium.Q6. What is cardiac output (C.O.) and what does it indicate?The amount of blood pumped by the heart during one minute is called the cardiac output. It is determined by the heart rate (HR) and the stroke volume (SV).Q7. If the SV of an adult at rest is 70 ml and their heart rate is 70 beats per minute what is their C.O.?Approx 5 l/min.OxygenationQ1. Briefly describe the functions of the cardiovascular system.The cardiovascular system consists of the heart function and circulation. The deoxygenated hemoglobin binds oxygen in the blood and carries it to the tissues.Q2. What is the function of deoxygenated hemoglobin?The deoxygenated hemoglobin binds oxygen in the blood and carries it to the tissues.Q3. Why is it important that the cardiovascular system functions effectively?It ensures that blood flows to the tissues for the resultant cellular uptake and utilization of oxygen.MetabolismQ1. What is the oxidation process, what is a by-product of this process and what is a quick way to remove if from the body?Oxidation is a process whereby oxygen and nutrients are converted in the body into work and heat. CO2 is a by-product of this process and it is removed from the body quickest by breathing.Q2. Why are changes in the cellular gas exchange level more pronounced in pulmonary VO2 than in pulmonary VCO2?The buffer for the CO2 is twenty times bigger than the buffer for O2.Q3. Give three examples of contributors to increases in energy expenditure (EE) and by how much they may effect our energy expenditure.Shivering and convulsions (200%) Injury (50%)Anxiety (30%)Q4. What is the “RQ” and what does the RQ tell us?It is the respiratory quotient –the ratio of CO production and O consumption. It tells us the kind of substrate that is mainly being metabolized and whether the patient is being adequately fed. Anesthesia ProcessQ1. Write the name of the symbol under each picture.1
- analgesia, painlessness
3. amnesia, forgetfulness
Q2. Name the three different types of anesthesia.
Local, regional and general anesthetic
Q3. Note down the six steps of the process of anesthesia in the order in which they are performed.
1. Preoperative assessment 2. Preparation of the patient
3. Induction 4. Maintenance
5. Emergence 6. Recovery
Q4. What is the beginning of the anesthetic process called?
Q5. What is monitored during preoxygenation to help determine the adequacy of O2 reserves and thus the correct time for intubation?
EtO2 and I-E O2’
Q6. What happens immediately following intubation?
The patient is usually connected to a ventilator.
Q7. What is included in the mixture of gas delivered by an anesthetic delivery system?
Oxygen, nitrous oxide or air and anesthetic agents.
Q8. Name the five inhalational anesthetics.
Halothane, enflurane, isoflurane, sevoflurane and desflurane.
Q9. What is the standard equipment used to deliver anesthesia?
An anesthesia machine, usually including a ventilator.
Q10. Name the two extreme kinds of patient circuit
A non-rebreathing system and a rebreathing system.
Ventilation, Patient Spirometry
Q1. What can patient spirometry assist with?
It helps to optimize ventilation and to prevent and diagnose problems with the ventilator or endotracheal/tracheostomy tube.
Q2. In what form can the information be delivered?
The information from the ventilated patient is integrated with other parameters on the monitoring screenin the form of numerical and graphical information.
Q3. What is meant by the folloving abbreviations I:E, Ppeak, PEEP, Compl and Raw?
I:E is the ratio between inspiratory and expiratory times. Ppeak is the maximum pressure exerted at the patient airway. PEEP is positive end expiratory pressure. Compl, compliance, is a measure of the distensibility of the lung-thoracic system. Raw is airway resistance.
Q4. While investigating the pressure/volume loop at the beginning of inspiration, we can notice that although pressure increases rapidly, volume is lower. Why?
Before flow can start, the pressure must overcome the ventilator tubing and endotracheal tube resistance and the surface tension of alveoli.
Q1. How long can the brain be without oxygen before it may suffer permanent damage?
Without oxygen the brain may be permanently damaged after only a few minutes.
Q2. What is an inadequate O2 supply at tissue level called?
Inadequate O2 supply at tissue level is called hypoxia.
Q3. Why is it important to have a fast oxygen measurement method?
It enables the breath-to-breath analysis of the patient’s respiratory oxygen.
Inhalational Anesthetic Agents and N2O
Q1. Which one of the anesthetic agents mentioned is recommended for asthma patients and why?
Halothane, it does not irritate mucous membranes. It is also a bronchodilator and therefore good for asthma patients.
Q2. What is another name for nitrous oxide?
Nitrous oxide is better known as laughing gas.
Q3. What is the most important characteristic of sevoflurane and how does that influence the anesthetic process?
The most notable characteristic of sevoflurane is its low solubility in blood, which makes it very quick in induction and recovery.
Q4. What does MAC stand for?
MAC = Minimum Alveolar Concentration.
Q5. Why is it important to have agent identification?
It helps to detect misfilled vaporizers, vaporizer contamination and situations in which two anesthetic agents are present at the same time.
Q1. Why is indirect calorimetry performed?
It allows the continuous and non-invasive monitoring of VO2 (oxygen consumption) and VCO2 (carbon dioxide production) and therefore the computation of RQ (respiratory quotient) and EE (energy expenditure).
Q2. Nowadays, how is indirect calorimetry performed?
By the use of gas sensors and flow/ volume transducers to analyze the gas concentrations and volumes of expired air.
Mixed Venous Oxygen Saturation
Q1. What is meant by mixed venous oxygen saturation SvO2 and where is it measured?
Mixed venous oxygen saturation SvO2 is the difference between arterial oxygen saturation and body oxygen oxygen saturation and body oxygen pulmonary artery.
Q2. What is the normal range for SvO2?
The normal range for SvO2 is 60-80%.
Q1. What is the CO2 waveform called ?
The CO2 waveform is called the capnogram.
Q2. EtCO2 is a non-invasive breath-by-breath indicator of three functions. Name them.
Ventilation, circulation and metabolism.
Q3. Why is it advisable to analyze both the numerical and graphical information of EtCO2?
Analyzing both the numerical and graphical information of EtCO2 may indicate the actual reason for abnormal values.
Q4. What is normoventilation?
Maintaining the EtCO2 between 4.7-5.5 % (kPa) or 38-42 mmHg.
Reference ventilatorBeginers Guide (D a t ex - O h m e d a Academy)
Prepared by Eng/