as an anesthesiologist I often get questions about the medications I administer and the procedures that I do but the critically important and very intricate anesthesia machine almost always flies under the radar my name is Max binstein and I'm an anesthesiologist filming here at the mount siai Hospital in New York City and in this video I give a tour of the pretty obvious centerpiece of the operating room that doesn't get a lot of attention despite its key role in anesthesia if you find this video interesting or helpful I'd really appreciate it if you liked it and subscribe to the channel let's dive [Music] in when I'm working with trainees I often describe the anesthesiologist top priorities as delivering oxygen to a patient's vital organs and also ensuring that patients are comfortable and with these two priorities in mind as context I think there's actually a pretty logical way that we can go through the anesthesia machine so if we start by thinking about where oxygen comes from here in the operating room it's actually piped in from a central storage system in the hospital and it comes into the operating room through the wall or the ceiling and it's really important for anesthesiologist have a good understanding of the plumbing of the gases that come into and out of the operating room because although rare if there was an issue with the hospital Central oxygen supply then we'd have to have an understanding of how to diagnose the problem and provide a solution and very short period of time here you can see a number of gases that are piped into the operating room Chief among which is oxygen which makes its way over to the back of the anesthesia machine this comes off the wall at 50 lbs per square inch pressure and you can appreciate that there are a couple of backup tanks behind the anesthesia machine including a green oxygen backup tank as well as a yellow medical air backup tank as oxygen and or medical air make its way through the anesthesia machine it's driven by this Bellow system which you can appreciate moving up and down to push the gas mixture through the circuit some machines have pneumatic controls for Bellow and others have electronic controls but functionally they work pretty similarly if an anesthetic gas is being added to the mixture then this is where the vaporizer allows that to join the circuit and that's controlled in a different part of the vent that we'll get to later Circle anesthesia circuits like this one feature a series of one-way valves that prevent gas mixtures from moving backwards here the bottom Arrow indicates the inspiratory limb of the circuit which is the part of the gas mixture that the patient is inhaling right now this circuit has a mask that's hooked up to it so that we can deliver anywhere between 21% and 100% oxygen and also anesthetic gas if we needed to later I'll show you how you can disconnect this and attach an endot trical Tube gas that's exhaled from the patient passes through this CO2 absorber so that CO2 does not accumulate in the circle breathing circuit depending on the configuration of the circuit sometimes gas is intentionally removed from it and that exits the machine through this purple waste anesthesia gas disposal line which ends up going into the wall and is piped out of the operating room and depending on the hospital actually just exits into the atmosphere from the roof of the hospital oh yeah and a lot of anesthesia machines have a Nifty little light that makes me feel fancy inside the operating room especially when it's dark that was an extremely brief overview of the anesthesia machine and now that we have Kobe here we'll get into some more of the interesting technical aspects of everything that makes this work going back behind the machine again I'll point out that these hookups for oxygen air nitrous oxide vacuum and the waist anesthesia gas disposal circuit are actually not interchangeable so it's not possible to plug in the oxygen tubing into the airport for example this is an important safety feature another critical safety feature is the presence of these backup e cylinders with oxygen and medical air which are also not interchangeable with each other it's worth pointing out that these e cylinders are filled at typically a much higher pressure with oxygen around 2200 PSI when full inside the machine a pressure regulator brings this down to about 45 PSI these tanks are opened and closed manually and it's important to ensure that they're closed when not in use because otherwise they can leak slowly and become empty over a period of days in addition to going through the main circuit of the anesthesia machine oxygen is also piped through this port here which can be connected to devices like nasal canulas or face mask and turned up manually up to 10 or 15 L per minute depending on the machine this very official looking bag to vent switch allows the anesthesiologist to toggle between a spontaneous mode where manual bag ventilation is possible or ventilator mode which isolates the bag as well as the APL valve that we'll talk about shortly it's important to be aware of the one-way inspiratory and expiratory valves which sometimes need to be troubleshooted shout out to the anesthesia techs who help out when there's an issue with one of these Valves and they need to be replaced on short notice anytime oxygen needs to be added quickly to the anesthesia circuit that can be done by pressing this green oxygen flush valve but keep in mind that this sees a pipeline pressure up to 50 psi which can result in gas flows up to 75 L per minute when patients are intubated the normal warming and humidifying functions of the upper Airways are bypassed and so this heat and moisture exchanger is designed to conserve the patient's exhaled heat and moisture keep it within the circuit it can actually play a pretty big role in maintaining a normal temperature especially in pediatric patients when the ventilator is turned off and the Machine is set to spontaneous bag ventilation mode this adjustable pressure limiting valve allows me to set the maximum amount of pressure in the circuit if the pressure in the circuit exceeds the number set on the APL valve the XX pressure is released this is really important for protecting patient lungs which technically become part of the circuit when a patient is intubated I'll show you an example of what that looks like when the APL is what we would describe as closed all the way at 70 mm of water you'll just have to take my word for it that there are 10 L per minute of oxygen flowing through the circuit which I can feel on my hand right now when I put my thumb on the circuit and olude it you can appreciate that this bag which is connected to the APL valve gets quite tight the maximum pressure inside the circuit is 70 mm of water which is what I dialed in to the APL valve now if I open the APL valve by turning it all the way down to its minimal setting and and then attempt to olude the Circuit again with my thumb you can see that the bag doesn't really inflate very much because not much pressure is allowed to build up in it the excess pressure is released by the APL valve switching off the ventilator and turning on spontaneous bag ventilation mode is a very helpful diagnostic tool to help troubleshoot any kind of intraoperative issue with breathing anesthesia circuits are designed with universal standardized connection sizes that allow for interoperability between basically any endot tricle tube and the circuit itself as well as between face masks like this one and the circuit itself this is important because often we'll start out by providing oxygen to an awake patient through a mask and then switch over to an endot trical tube after the patient has gone under general anesthesia and been intubated then if the patient's being extubated at the end of the case we'll disconnect the endot trical tube once that's been removed and reconnect the face mask to provide support with oxygenation and ventilation the CO2 absorber that's present in circle system effectively eliminates carbon dioxide from the exhaled gases which allows the patients to rebreathe them this allows for the conservation of heat and volatile gas in the circuit but keep in mind that these absorbents have a limited lifetime so one of the indicators you need to change it is if it starts to change color and another indicator might be that your patient intitle CO2 starts to creep up because they're rebreathing their exhaled CO2 some anesthesia workstations have a lot of screens attached to them like this one but ultimately there's only one screen that displays the actual information from the ventilator itself in this case it's the screen that's right behind me to turn this particular machine on we'll just hit start case and it will bring up some basic parameters that I can dial in that will help me with some default settings I'll go ahead and leave everything default for now and hit start case on the bottom left of the screen for this particular ventilator you can see information related to gas G flow starting on the left hand side we've got our fraction of inspired oxygen that we can dial in either with a button or by using this scroll wheel we can also dial in the amount of flow that we have going through the machine this is in liters per minute we better turn it down to not waste oxygen you can also dial in the amount of volatile anesthetic that you would like the patient to receive which can also controlled with the scroll wheel we better leave that off so I don't accidentally anesti myself we've also got some additional parameters we can dial in such as some details about the circuit and whether we'd like to include nitrous oxide in the circuit as well as more information about the flows on the bottom right corner for this particular ventilator we've got the actual ventilator controls starting with the ventilator mode here we have quite a few modes that are available and depending on what ventilator you're using you may have some that are similar to these fundamentally most ventilator modes are based either on volume control or pressure control some combination or riff off of that there's also a pressure support ventilation mode which I find to be very useful at times the rest of these controls are for dialing in specific ventilator parameters such as tital volumes respiratory rate inspiration to expiration ratio and positive end expiratory pressure the right hand side of the screen consists of buttons mostly for customization as well as monitors and importantly there's a timer so that you can actually time the surgeon when they tell you how long the case is going to be I'm just kidding we don't actually do that well mostly kidding the rest of the real estate on the screen is highly customizable and in this default view there is information about peak airway pressures title volumes CO2 that's exhaled by the patient that's called intital CO2 as well as a pressure volume Loop respiratory rate information gas information which in this case is oxygen that's both intital oxygen so what the patient is breathing off and the fraction of inspired oxygen which is what we have dialed in for the patient to inhale finally we've got information about our volatile gas isof Florine and this case how much is being exhaled and how much is being inhaled this is an extremely superficial look at the anesthesia ventilator and the ins and outs of how to use it are learned through the years of training becoming an anesthesiologist the other screens that are attached to this anesthesia workstation include patient monitors which I go through in a separate video which you can watch by clicking this link right here as well as a couple of specialty pieces of equipment that are used in cases where you'd like to monitor close information about the patient's brain so in this case this is a processed EEG monitor which looks at the brain's electrical activity and this is a regional oximetry device that allows us to look at the oxygen saturation of the front part of the brain and then the last screen that's right behind me is actually just a computer because all of the anesthesia records in this Hospital are kept electronically on a computer I've been recording this video in an operating room that's typically used for cardiac surgery and if you'd like to watch another video I go through the setup for cardiac anesthesia you can check that out right here thanks very much for watching I'll see you next [Music] time