We could now set working pressure up to 120cm. Respiratory rates changed to 0.5 (to make weaning easier) up to 120 breaths per minute so that we could control infant breathing.

The ventilator was operated as a pressure-cycled unit by changing the mode control to "press.contr" and adjusting inspiratory pressure control to the desired pressure level. Inspiratory time percent where increased to a maximum 80 percent enabling reverse I.E. ratios to be delivered. Minute volume increased to 40Lmin.

Triggering level "sensitivity" could be set at level below the preset positive end expiratory pressure (PEEP) level. As the PEEP was changed, the triggering level automatic compensated to maintain the same degree of inspiratory triggering effort. It also could be  electronically adjusted to 50cmH20.

Monitors and alarms could be set using a selector knob. Finally it had a flush button to allow injection of a completely fresh concentration of a gas.

The answer to respiratory flashback question No. 17: Congratulations to Jhon Conniff, the only person who submitted the right answer: pressure support. The new mode was added to give pressure support during spontaneous breathing in the synchronized intermittent mandatory ventilation (SIMV) mode. The advantage to this system was that it helped the patient overcome tubing and other circuit resistance during spontaneous breaths.

Question No. 18 is one of my favorite. To me it's about what Respiratory Therapy is all about: What was the Servo 900c capable of doing that was never done before?

Also, I would like to welcome to the website: Dinosaur Thalob from Tripoli, Libya. Abby Navarro from the Philippines, Bedair Haroun from Saudi Arabia, and Hipolito Mendiola from Mexico City. They're using the equpment that we're talking about now as the primary instruments to treat patients. 

As we continue on our path through respiratory history, we come to newer ventilators like the Servo (900, 900b, 900c). It was the first vent to use electronic feedback loops with an integrator unit to deliver guaranteed tidal volume. The loops controlled input gas flow based on output delivery with automatic adjustment to meet a preset volume. These ventilators were on the cutting edge of technology, and led the transition to computer-controlled devices.

The Servo was time-cycled and pneumatically powered. It could be an assistor, a controller, or anassistor/controller when used in conjunction with synchronized intermittent mandatory ventilation (SIMV), continuous positive airway pressure (CPAP), and positive end expiratory pressure (PEEP).

The maximum preset working pressure available to empty the bellows to deliver gas to the patient was adjustable to 100 psig. And the preset inspiratory minute volume, which was used to establish the desired minute volume delivered to the patient, was adjustable from 0.5 to 25 L/min.

It could do 6 to 60 breaths per minute (so it would work with adult or pediatric patients) and you could control the peak flow rate as a function of time through the new inspiratory time percentage control. You could adjust the time between 15 and 50 percent of the breathing cycle. Also new was a pause time percentage, which allowed you to adjust the pause that occurs at the end of an inspiration but before the beginning of an exhalation by up to 30 percent.

The flow pattern selector switch had three options: Square wave form was the wave form for a patient that breaths normally .The accelerating wave form was for a person who had a restrictive problem (a problem getting air in.) The decelerating wave form was for a person who had problem getting air out, like in chronic obstructive pulmonary disease.

We used maximum expiratory flow to create expiratory retard by setting the sensitivity usually 2 to 3 cm below the base line working pressure. Sensitivity makes it easier for the patient to start the inspiratory phase of breathing.  

The oxygen blender was separate from the ventilator. It had two hoses, one set up to compressed air and the other hooked up to O2. The blender had a numbered system to give accurate percent of oxygen.

Humidification (a new feature on this vent) is one of the important things to have on a ventilator. It not only gives you moisture, but it heats the air to the temperature that the body requires.  Today's vent have many types of heated humidification, but in the old days, the cascade and the concha where the two to choose from. 

The answer to Flashback Question No. 16: What caused the small tube on the right side of the ventilator to give an incorrect LED read out? The tube gave an inaccurate LED read-out when water came in contact with its sensor.

Question No. 17: What was the big change made between to the Servo 900c that set it apart from earlier models?

Back in the old days, most schools only had two ventilators to learn from.

Bear 1 & 2: They were electronically controlled, pneumatically powered, time, pressure, or volume-cycled ventilators. They provided control, assist/control, synchronized IMV, and CPAP modes. They had over 20 different display and signals alarms.

SIMV: Once IMV rate was established, the machine monitored the patient's spontaneous breaths. If the patient had received an assisted breath, the machine would not deliver another breath until adequate time has passed for exhalation to occur. This approach prevented stacking, leading to increased airway pressure and possible barotrauma.

This ventilator also had one of the first LED displays that would read out both rates, tidal volume, minute volume, I.E. ratios, and temperature. It had an O2 control, sensitivity, nebulizer, visual reset with an alarm silence, peak flow and inverse ratio limits and PEEP, a manometer to measure peak pressure and inspiratory pause. A complete assembly of this device would include attachment of a breathing circuit, humidifier, and other accessories.

There were other vents, of course, but I'm telling you about the ones most old-school students learned on.

The answer to Flashback Question No. 15: How would you make the leak? Go to blog 15 for the correct answer given by Joel Price from NH. He was the only one to get it right!

Question # 16: There is a small tube on the right side of the vent. What caused it to give an incorrect LED read out?  

As I reminisce about old school ventilation, I want to share with you what would seem impossible today: I came off the street with no health care education. I didn't have my CRRT or RRT. As a matter of fact, I had no science education at all. Respiratory Care school at this time was only six weeks long.

It was only a few years after I started working in the hospital that I got a dreaded call from the emergency room. We had a 7-year-old, cold water drowning. She had been under for 45 minutes and was about 40 minutes out from the hospital. I was scared to death! But I knew I had a job to do, so I concentrated on what needed to be done.

I set up the PR-2 ventilator. (Check out a photo of it here) It was a simple R.R. Then I set up an inspiratory pressure with a spirometer so I could get an tidal volume and set up a blender for oxygen. The flow on the ventilator didn't really work.

The open heart and emergency room teams soon were with me. The little girl has a core temperature of 90, no heart rate, and she was not breathing. We heated up the IV's. We didn't think that she would make it. The teams kind of gave up after an hour. But I was only 20 years old; I was not about to let her die! I kept doing compressions and, my God, I got a heart rate. I screamed for everyone to help me.

Today, she's a beautiful mother. There were no side effects. Her story was posted in the first respiratory magazine in the early 70s. If you were around then and still have the magazine, I would love a copy. I lost mine. It's a reminder that miracles happen every day in intensive care units.

The answer to Flashback Question No. 14: What would stop the spirometer from stacking? The spirometer would hold only 2 liters. Sometimes, we would get minute volume's of 20 liters (too much for the bellows to handle) so we opened the top of the spirometer and made a leak.

Question No. 15: How would you make the leak?

We learned that we could better control patients with all new tools like IMV,  positive end expiratory pressure,  and controlled O2s.

On the side of the ventilator was a T-shaped piece with an exhalation port on one side and a bottle under the T-piece to collect water. The expiratory port went up a long tube to an incased larger tube that had bellows that would move up and down based on your expiratory effort. By reading the numbers on the side, we could measure exhaled tidal volume for the first time.

But now, we ran into two problems. The first was that patients' breathing was not in sync with the ventilators' breath, the second was that when the patient would breathe too fast the bellows would stack. Of course, the doctors would stay away because they didn't want to have anything to do with it and there were no books to help. It was up to the first generation techs' responsibility to figure it out.

The answer to Flashback Question No. 13: What was an H-Valve ?: Since I started this blog, only a few people have correctly answered my flashback questions. This week, I decided to give credit to the person who got last week's question: Jean Bolton from Sheldon, IA. Read "Finally, RT's Get Noticed" for the correct answer to Respiratory Care Flashback #13.

Question No. 14: What would stop the spirometer from stacking?

As ventilation abilities began to increase in the world of health care, a new rule of thumb evolved:  put more difficult patients on life-support, and get them off of it sooner.

Intermittence Mandatory Ventilation (IMV) opened that door. The MA-1suddenly did a lot more to help control the needs of patients. A box with a control respiratory rate, tidal volume, oxygen percentage, still new flow rates and Singh's along with alarms and sensitivity were important new tools to improve our emerging field of respiratory care.

With Positive End Expiratory Pressure and IMV respiratory equipment was becoming fun! And with all this new equipment, suddenly respiratory therapists were starting to get noticed. Our peers' eyes were starting to open. It was just the beginning...

The answer to Flashback Question No. 12:  In the MA-1, where did the biggest leak come from? The cascade. The cascade was a bowl with a screw on top along with a tower in the middle. If the top wasn't on tight, air would leak out. Keep in mind this was your responsibility! There were no bio- med or engineers to help you. You had to bag until the next shift, and every shift was comprsed of only one person.

Flashback Question No.13. What was an H-Valve ?

We later realized that we were dealing not only with ventilation but oxygen levels. Thus a new term called positive end expiratory pressure (PEEP) came into being because we could now control O₂ levels. And, most importantly, was the first intermittent mandatory breathing (IMV). This development got the patient off of the machine sooner because the patient's breathing would not get out of sync with the ventilator, wasting valuable energy needed for healing. We also learned that we needed a machine to give the patient humidified air at body temp to match the body's needs. It was called a Concha.

The answer to Flashback Question No. 11: When we went to the pharmacy, what would be the first thing we asked for, other than medications? It was not medication, but a pocket holder! We all had to wear white-only coats. The pocket holder prevented all the tools that we walked around with from turning our lab coats into a mess.

However, a lot of accepted procedures did change in the profession in the early days -- within a few years, saline became preferred over sterile water, there was no unit dose medicines (we had to mix our own), MDIs hadn't been invented yet, and longer lasting, and more easily  accessible drugs became the norm.

Here's how drugs were administered: First, a syringe was filled with 3cc of either saline or sterile water, and then the medication was measured with a dropper in the proper dosage. Along with that we also had to set up an O₂ cylinder for delivery of the mist, set up the circuit, and place it into the nebulizer.

To give a treatment that is oh-so-simple today took us much longer to do back in the early days of respiratory. With 40 to 50 treatments to do daily, much tinkering was needed to keep the system functioning. Tinkering took time. And lots of it.

Answer to Flashback Question No. 10: What was the most important thing we carried with us when working on a mist tent? We had to carry a screwdriver that had a sharp tip on to clean out the particulate matter in the Venturi. If this was not done the tent would not mist.

Back in the 70s when fall was in full swing and upper airway problems flourished, the mist tents would go up like crazy in hospitals. The mistier - and wetter - the better. But now the CDC has recommended that they not be used. I often wonder how much the water actually blocked oxygen from getting to the patient.

One major blind spot with the once-popular tents was the lack of any procedure to prevent the transfer of water from one room to another. After all, the  tent door was always open from families going in and out all day long. We did not know then that it was possible for the families to take airborne, droplet, or even secretion isolations back to their own homes.

Once again, time, education, and change have improved care.

Answer to Flashback Question No. 9: What was the biggest problem with the mist tent on 02? It was the toys brought in for the children -- toys, which could create a spark in those days. The mist tent would go up in a blaze in less than a minute. Because of this, clinicians routinelt were asked to watch a movie on how quickly a child could burn to death, to reinforce the importance of safety measures.

Flashback Question No. 10: 10 What was the most important thing you would carry with you when working on a mist tent?

The change of seasons brings lots of airway problems into the emergency room. What's very harmful is the temperature differential of going back and forth between the cold outside and a warm interior. What does it inflict on the human body? Croup and bronchitis, to name but a couple of possibilities.

As I recall, most upper airway problems in the '70s were treated by child/adult mist tents. The more the mist, the better it worked. Even though it was always very cold and wet in the tent, some mothers would get in the tent with their child, willing to be drenched and miserable.

To keep it cool we had to put ice in the back of the tent. The real pain in the butt was the constant monitoring of the water traps so they wouldn't overflow, making the floors slippery and dangerous. We had to be janitors as well as respiratory therapists.

Flashback Question No. 9:  What was the biggest problem with the mist tent on 02?

Answer to Flashback Question No. 8: When the paramedics arrived at the scene of a code, there was a machine on the  patient doing chest percussions. What was the device that was on the patient? A cravass type cage was placed over the chest with a piston-driven arm that would do compressions automatically, giving the patient a breath every five strokes. However, after such a procedure, the patient would arrive at the hospital with a hole in their chest.

Flashback 8: It feels as though I've been working my shift in ER for seven days straight. All the rooms are full of  IPPB with O2 cylinders. A child with croup comes in requiring a CAM tent. Just as I am about to get it ready a code blue comes in. I have just enough time to start a cool mist, handing the tubing over to the parents so I can get ready for the code blue by setting up the Birds and Bennets, which were the ventilators of choice back then. The ambulance is three minutes out.

Oh no! Code blue CCU. I hope I have time to get the airway in, have the nurse bag, and go back to the code in ER! When the paramedics arrive there is a machine on the patient doing chest percussions and every five compressions it gives a breath.

Flashback Question No. 8: What was the device that was on the patient?

Answer to Flashback Question No. 7: There is a manual device in the center of the PR-2 that you can turn on and off because of its hardness and smoothness. Rubies (yes, real bling!) were placed into the PR-2 to supply the aforementioned hardness and smoothness.  Thousands of them got tossed out in the end.

My next step is to check my ventilators (one Mark-14 Bird and one Purtent-Bennet PR-2), a CAM (child/adult mist) tent, and about six oxygen cylinders. It is important to remember that handheld nebulizers were still more than five years away!

Every treatment was done with intermittent positive-pressure breathing machines. All equipment was non-disposable, so every piece of equipment had to be personally hand-carried to Central Services, taken apart, sterilized, put back together correctly, and returned. With 40 to 60 procedures daily, this process made a difficult job even harder.

We had to make the most of our time. You really had to have your ducks in a row. The earlier you prepared for the day, and the more organized you were, the greater number of patients you could treat. Also, the better your assessment skills were, the sooner you could treat the more critical patients.

The other doctors were still not sure that this new mode of Respiratory Therapy medicine would work and their doubts added to the pressure on us to perform. It took at least five years before we earned their trust.

Answer to Flashback Question  - Do you ventilate a neonate with humidified air and body temperature? What is the current protocol ? Remember? I want to get the answer from you! Do you ventilate a neonate with humidified air at body temperature or room air? I'm waiting...

Flashback 6: Once again it's late in the evening and I get called in to deal with a 34-week premature baby, knowing that I have to get up early and work the next day! I hope it won't be a long night. I already know we can't get a doctor that time of night and a level three nursery is hours away.

As I get into my scrubs I can hear my name being called. The neonate isn't breathing. I set up my manometer and start to manipulate the anesthesia bag manually because we didn't have the equipment back then to automatically ventilate the baby.

I ask how far out the ambulance is and am told it is at least three hours. This delay was not unusual in the early days so I start to bag and mask the neonate 5/25. Because of fog, the ambulance is delayed not for three but for four hours. Other than a nurse to administer meds and myself, there was no one else to back us up.

The feel it requires to work the bag that long is unheard of today, due to the lack of an ET tube and ventilator. Me, being under the warmer for hours, also made conditions much more difficult.

What happened that night started to breed a new kind of specialty in respiratory therapy. It took a combination of guts, experience, and attitude to take the concept of service to this new level. We were risking both our careers and our reputations every day to save lives.

Answer to Flashback question No.5: What was the best "old school" way to ventilate an infant?The bag and mask technique was the best way in the early days due the lack of proper equipment training.

Flashback question No. 6: Do you ventilate a neonate with humidified air and body temperature? What is the current protocol ?

Flashback 5: In the early days of respiratory therapy, one would often hear the words "feel" and "change" because everything depended on touch, not technology. A willingness to take chances was necessary in those days because we found ourselves in situations not covered in any medical texts, and there was no going to Google to find an answer. Often we had to make educated guesses based on intuition and experience.

For instance, take the case of airway pressures in premature babies. In the beginning, we thought it took a lot of pressure to ventilate compromised babies, so we would use higher pressure than necessary. Boy, how quickly we learned that that wasn't the case.

Another misconception back then was the notion that it would be helpful to place little ones in a Heimlich position, tipping them on their heads, so as to drain the secretions causing cranial pressure. The pressure on the still soft skulls, and many other complications caused by this position, if monitored, would have been dangerously high. The link between this procedure and brain damage in infants was eventually discovered and change came rapidly, creating better care. This is one of many bits of knowledge that we take for granted now that was unknown back then. 

Not to worry, the babies didn't get as compromised as you might think. Thank goodness those little one were so tough. Often we were on our own with no backup. You must keep in mind that general practitioners did not like to (or want to) work on infants. It took a lot to have someone on call for "bad babies" so most of the cases would be sent out.

Answer to Flashback Question 4: Why was the Baby Bird hard to work with? The Baby Bird was hard to work with due to the amounts of tubing and the weight of all the water traps which caused premature extubations and difficulty in transport.

Flashback 4: I had just finished a very busy day at work and knew I would be on call for the rest of the night. As expected, as soon as I got home I had to go right back to the hospital. What really blew my mind was that the nurse on duty who had summoned me did so because she did not know the difference between a compressed air flow meter and an oxygen flow meter. Oxygen flow meters weren't hooked up to the wall in those early days -- the hospitals usually used oxygen from tanks.

Once more, as soon as I returned to my apartment, I got called back again that same night to the hospital for a code blue! Staffing was minimal back then so there was no staff to help me when a second code blue came over the loudspeaker. The proper drugs were administered to my code blue as I was busy ventilating the patient, but I was left alone to do both airway and compression at the same time because staff was busy with the other emergency.

What would you have done?

I set up a P.R.1 at a rate of 12 and started at a five-to-one compression ratio to keep oxygen saturation, R.R., and blood pressure good until I could get help. About 45 minutes later, someone finally arrived to assist me. The patient ended up doing fine and he went home in a week. Just for the record, I made a dollar and a quarter an hour for all of that!

Answer to Flashback Question 3: What is Vickers medical equipment used for? The Vickers, which came out of Long Beach, Calif., was the first hyperbaric chamber. The Navy used it to treat the bends. One of its main drawbacks was that it had eight locking devices that took too long to get the patients out of and the cranking noise that the locks made scared the dickens out of the patients. In less than a year, the Sechrist hyperbaric chamber replaced the Vickers and it had only one locking device, thank God.

Flashback Question 4:  Why was the Baby Bird so hard to work with? Answer next week. Take a guess!