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Anesthesia/Complication of Endotracheal Intubation

NOMINATED TOPIC | January 26, 2021

Anesthesia/Complication of Endotracheal Intubation

1. What is the decision or change you are facing or struggling with where a summary of the evidence would be helpful?

A need for Mandated Standards of Care in Anesthesia to prevent disastrous life-long complications. Standards that only take a moment and all research and the manufacturer directions say to perform. These two simple safety measures are: Check that the blood supply is intact to the trachea with a pressure measuring device with every intubation and use the correct size tube for the size of the patients tracheal diameter.

I have been trying to get attention to a catastrophic, debilitating and preventable life changing and even fatal complication of anesthesia due to the lack of safety measures. Simple safety measures to prevent the blood supply to the area under the vocal cords from being shut off from the cuff of the endotracheal tube. When there is a lack of blood and oxygen supply, it causes ischemia, necrosis and ultimately, subglottic stenosis (SGS). It happens when the tissue dies from a lack of oxygen and blood perfusion, it forms dense scar tissue and slowly and progressively narrows the trachea until the patient can no longer breath. Because this process takes years to develop and be diagnosed, airway doctors label the patient as idiopathic and will not consider any previous intubation as cause, despite the fact that the #1 known cause of SGS is an intubation with high cuff pressure and use of too large of endotracheal tube. It only takes 15 minutes of no oxygen or blood for the damage to occur. In relation to Covid: research also shows the #1 associated risk factor of Ventilator Associated Pneumonia (VAP) is LOW cuff pressure, allowing secretions to enter this lung and increases morbidity, mortality and ICU days. It is critical to maintain cuff pressure between 20-30 through direct pressure measurement and not depend on minimal occlusive pressure or the palpation technique of cuff pressure determination - both long ago determined to be extremely inaccurate and placing patients at high risk of harm. Please read the following and help me protect patients from this nightmare because the airway is not protected with mandated simple safety standards, despite all research and the manufacturer saying these safety measures are necessary.

I have reliable and science based evidence that shows even a short term intubation can result in the catastrophic diagnosis of subglottic stenosis many years afterwards. These patients that are harmed have been hidden under the guise of idiopathic subglottic stenosis (ISS) for far too long. The evidence is compelling; the absolute majority of these patients labeled as idiopathic have had an anesthetic prior to the onset of their narrowed airway symptoms, patients all have their site of stenosis directly under their vocal cords, exactly where the cuff of the ETT sits, and the pathology results of the stenotic tissue of idiopathic and intubation caused is the same. Although an intubation with high cuff pressure and use of too large ETT are the known primary causes of SGS, ENT airway doctors refuse to look at prior intubations as cause, preferring to label them as idiopathic. To exclude an intubation if it wasn’t recent, within 2 years, prolonged or due to hormones are simply opinions and not evidenced-based.

The average time length is 8 to 10 years from an intubation to diagnosis of SGS in patients labeled as ‘idiopathic’ and those who are intubation caused. There is an average of 3.5 years from symptoms to diagnosis for both idiopathic and intubation caused. Both groups of patients are misdiagnosed and wrongly medically treated during this time period; they are most often incorrectly diagnosed and mistreated for asthma, ‘silent’ gastric reflux, sinus problems, being old, being out of shape and panic attacks. Symptoms of SGS are directly related to the degree of narrowing in the trachea and do not begin until the diameter is reduced to approximately 8 mm by scar tissue. It is unknown why the short time frames had ever been imposed for an intubation to be the etiologic factor of SGS since this data shows it takes years for it to be diagnosed after an intubation. The rate of SGS is rapidly spiking due to intubations in Covid - just think if this suffering and long term complications can be prevented! LOW cuff pressure is the #1 associated factor of Ventilator Associated Pneumonia (VAP) allowing for increased morbidity, mortality and ICU days. It is prevented with a cuff manometer to make sure the pressure is within the narrow safety parameter of 20-30 cm H2O pressure.

2. Why are you struggling with this issue?

The fact is that all research shows damage to the trachea can occur within 15 minutes, the manufacturers issue strong warnings to use a cuff manometer but there has been a total system failure in anesthesia to protect patients from KNOWN HARM and institute safety measures. I will discuss these above facts with you as well as the false assumptions that have prevented the proper correlation between prior intubations and later diagnosis of stenosis when we meet. A few of these false assumptions to be discussed are:

  1. An intubation must be prolonged to be the cause: FALSE. There is no research to support this. ALL research show damage begins within 15 minutes of high cuff pressure and resultant compromised tissue perfusion. There is no part of the body that can withstand over 15 minutes without a blood or oxygen supply and the trachea is no different. 
  2. An intubation must be within 2 years or recent to be the cause: FALSE. There is no research to support this. All patient evidence points that it takes years from intubation to correct diagnosis. Most patients are diagnosed at a tracheal diameter of 4 mm and it is errant to put a 2 year time limitation for this narrowing to occur. No one knows the exact length of time it takes for a trachea to narrow with dense scar tissue from a beginning diameter of perhaps 12-14 mm (and larger) to 3 to 4 mm — where SOB with rest occurs and most are diagnosed. There is no other disease process that have an imposed time limitation for a diagnosis and it is a medical embarrassment for tracheal stenosis to be the only one. 
  3. Since more women than men are affected, it must be hormones: FALSE. There is no research to support this. ALL research shows women have smaller tracheas and when man sized tubes are used, damage happens. A size 7 ETT is only a reflection of the inner diameter, the outer diameter is 9.6. Female tracheal diameters can be as small as 7-9 mm and when the balloon is over-inflated, the cuff pressure now exceeds tracheal perfusion causing ischemia and necrosis. Mean cuff pressure of men = 27 and within the safety margins. Mean cuff pressure of women = 56 and exceeds tracheal perfusion. In cuff pressures comparisons of men vs women, 10 women had pressures over 100 vs. only 1 for men. 
  4. The injection and palpation technique of cuff inflation is accurate and reliable, protecting patients from harm. FALSE. ALL research shows this technique is highly unreliable and will result in predominately high cuff pressures and compromised tracheal perfusion. The only reliable method of cuff pressure inflation is with a cuff manometer yet there is no safety standards to mandate its use — allowing for high cuff pressure and resultant harm.
  5. The ETT cuff is low pressure and therefore safe. FALSE. The cuff is low pressure until it is over-inflated. The moment it is over-inflated, it becomes a high pressure cuff.
  6. SGS is not preventable. FALSE. SGS is easily preventable through evidence based care of preservation of tracheal perfusion and use of correct sized ETT for the size of the patients tracheal diameter.
  7. There are no law suits so there is no problem: FALSE. Patients are labeled as idiopathic instead of intubation related and patients are told it is “too hard to prove” that the intubation is the cause — even when the patient insists all symptoms of a narrowing airway began after a surgery. The 2 year statute of limitation for lawsuits also prevents most patients from filing because they are not diagnosed until years later.
  8. SGS is nothing to fear. FALSE. SGS can cause a patient to literally suffocate and it destroys their lives emotionally, financially and physically. They struggle to breath, can’t exercise or ride their bikes, can’t carry laundry up a flight of stairs or ride bikes with their children. They go bankrupt due to medical costs, they lose jobs, they lose their voice due to recurrent laryngeal nerve damage, they cough constantly due to damaged ciliary action and narrowed airways; a common cold can kill. Their lives are controlled by brief periods of easy breathing after a dilation followed by the constant struggle to breathe as their tracheas begin to narrow again.
  9. SGS is easily treated and curable: FALSE. Patients have to undergo constant dilations and laser surgeries to keep their tracheas open. If lucky, they will get months or a few years between dilations or laser treatments. Some patients will have tracheal resections but these resections can fail. In one case, which is not unique, a patient has had over 20 dilations in a 2 year period. Just think that this suffering and financial burden could be prevented with simple safety measures of using the correct size ETT and preservation of tracheal perfusion.
  10. SGS is a rare problem: FALSE. There are currently over 4,600 members in just one on-line support group with more patients being ‘welcomed’ every day. One estimate is up to 11% of intubated patients will develop post-operative tracheal stenosis, even after short term intubations.
  11. There are no mandated standards in anesthesia to prevent this: TRUE. Literally all research indicates a cuff manometer MUST be used to maintain tracheal perfusion yet neither the ASA nor the AANA have mandated standards to protect patients from this preventable harm. Even the ETT manufacturer’s directions are to use a cuff manometer yet anesthesia providers ignore this allowing harm to occur to countless patients.
  12. From the ETT manual “WARNINGS Cuff inflation by “feel” alone or using a measured amount of air is not recommended because resistance is an unreliable guide during inflation. Intracuff pressure must be closely monitored with a pressure-monitoring device. Do not over-inflate cuff. Ordinarily, cuff pressure should not exceed 25 cm H2O. Over-inflation can result in tracheal damage…” Adverse reactions listed by the manufacturer include development of dense or diffuse fibrosis invading the entire glottic area, replacement of the trachea wall with scar tissue, subglottic annular cicatricial stenosis and tracheal stenosis, fibrin deposition, rupture of the trachea, ulcerations exposing cartilaginous rings and formation of subglottic web. Clearly these adverse post-intubation events are related to the pathophysiology of damage from high cuff pressure and use of too large ETT and can be prevented by following the manufacturers guidelines to use a tracheal-perfusion pressure measuring device (cuff manometer).

There are decades of scientific research that show the damage of high cuff pressure and use of too large ETTs cause. There are decades of research that shows the inaccuracy of all cuff inflation techniques except direct measurement to keep the trachea safe. All research shows cuff pressure must be kept within the narrow safety margin of 20-30 cm H2O pressure. All research shows tracheal perfusion begins to be compromised at pressures greater than 40 with total occlusion above this. All research shows lack of blood supply results in ischemia, necrosis and subsequent development of scar tissue (SGS). All research shows the cuff manometer is the only reliable method of cuff inflation to preserve tracheal perfusion. All research recommends cuff inflation with a cuff manometer for every intubation. All research recommends the proper sized ETT for the size of the patients tracheal diameter. ALL of this research is ignored.

3. What do you want to see changed? How will you know that your issue is improving or has been addressed?

To prevent subglottic stenosis, the following measures must be enacted immediately: Maintain tracheal perfusion with every intubation, regardless of length of intubation, through direct cuff pressure measurement with a cuff manometer. Maintaining proper cuff pressure also protects the RLN from injury — the nerve that innervates the vocal cords. Utilize the size of ETT that correlates with the patients tracheal diameter to prevent injury. Discard the ‘one size fits all’ philosophy of endotracheal intubation.

It is apparent this letter and call for immediate patient safety measures is highly unusual. I gain nothing and risk my reputation on this research and call for change. My only goal is to prevent the needless and long term suffering that patients with SGS experience. At every hospital I have worked and presented this research, there was a placement of cuff manometers in every anesthetic location and a downsizing of ETTs, especially for women. Neither the major medical centers nor small hospitals would have ever spent the money necessary for cuff manometers if not for sound scientific proof of its need. One point that needs to be made is that a cuff manometer costs only $179; what is a patients trachea worth?

Anything and everything must be done to prevent needless long term catastrophic suffering from the lack of safety standards in anesthesia. If you believe in the first tenet in the Oath of Hippocrates of “First do no harm” you must take this letter seriously and have prevention of harm as your first priority.

FYI: Just ONE scientific research article that shows the damage of ETTs without proper use: Complications of endotracheal intubation and other airway management procedures, p. 308 JV Divatia, K Bhowmick. Tracheal stenosis: Intracuff pressure is transmitted laterally against the wall of the trachea. Ischemia and eventual necrosis occur when the lateral tracheal wall pressure exceeds the capillary perfusion pressure of about 25 mmHg. Necrosis of the tracheal mucosa leads to sloughing and ulceration of the mucosal membrane, exposing tracheal cartilage. Continued ischemia may be followed by partial or complete destruction of cartilaginous tracheal rings and loss of the structural integrity of the affected tracheal segment, leading to tracheal dilatation. Healing of the injured tracheal segment during any stage of this process may lead to a tight fibrous stricture (tracheal stenosis). These can be prevented by proper management of low pressure cuffs. Only high volume, low pressure cuffs must be used, and the cuff inflated to pressure not exceeding 25 mmHg or 30 cm H2O. Over inflation of these cuffs causes them to function just like high pressure cuffs. It is therefore essential to inflate only as much air as is required to just seal the air leak during IPPV (minimal inflation technique), and to check the intracuff pressure with a cuff-pressure manometer.

4. When do you need the evidence report?

Sat, 05/01/2021

5. What will you do with the evidence report?

Mandated safety standards with every intubation to prevent harm. The manufacturers direction and all evidence based research needs to be followed every time a patient is intubated. Mandatory cuff pressure measurements are also needed in ventilated patients in the ICUs to prevent ventilated associated pneumonia. Research excerpts: Tracheal tube and laryngeal mask cuff pressure during anesthesia — mandatory monitoring is in need, Rokamp.

When the cuff to tracheal wall pressure exceeds the tracheal pressure (27-40 cm H2O) for approximately 15 min, the tracheal mucous membrane becomes ischemic. Endotracheal cuff pressure and tracheal mucosal blood flow: endoscopic study of effects of four large volume cuffs, Seegobin van Hasselt.

Low pressure cuffs, however, may be easily overinflated to yield pressures that will exceed capillary perfusion pressure. ……This impairment of tracheal mucosal blood flow is important factor in tracheal morbidity associated with intubation. Hence it is recommended that cuff inflation pressure of 30 cm H20 (22 mm Hg) should not be exceeded. Page 965. …Nevertheless, these cuffs (low pressure) may easily overinflated, generating excessive lateral wall pressures. Pg. 965. IMPORTANT: look at pg 966 for imaging of pressure vs blood flow. …..we found evidence of obstruction to mucosal blood flow at a lateral wall pressure abut 30 cm H20. Pg 968. Correlations between Controlled Endotracheal Tube Cuff Pressure and Postprocedural Complications, Liu, Zhang.

Excessive inflation of the ETTc would produce high pressure on the tracheal wall, thus affecting blood perfusion of the tracheal mucosa resulting in ischemic necrosis of the tracheal mucosa. pg 7 see also imaging. NOTE: The reason for the discussions of lateral blood flow is because the circulation to the trachea is supplied laterally. SEE Gross and Microscopic Blood supply of the trachea. Salassa Pearson Diagrams page 102, pg 105 imaging Association of airway abnormalities …Poetker, Eltema.

The most common risk factors for the development of SGS include endotracheal intubation, tracheotomy, and external trauma with intubation the most common precipitant of LTS. Stenosis associated with intubation is thought to arise from the direct mechanical pressure exerted onto the tracheal sidewall from the cuff or even rom the tube itself. Ischemia related to this compression can lead to necrosis, edema and ulceration. pg 436 COMPLICATIONS OF ENDOTRACHEAL INTUBATION AND OTHER AIRWAY MANAGEMENT PROCEDURES Dr. Divatia J. V.1 Dr. Bhowmick K. Page 314 Delayed tracheal injury: Is almost always cuff related, and can be minimized by  meticulous cuff management. Postintubation Tracheal Stenosis Wain Necrosis induced by pressure-related loss of regional blood flow is the central injury leading to PITS pg 284 A spectrum of PITS lesions has been recognized. Cuff stenosis is the most common….Pg 285. Any patient who develops symptoms of airway obstruction, who has been intubated/ventilated in the recent past, must be considered to have an organic lesion until proved otherwise. Pg 285.

NOTE: there is NO reasoning offered for what the recent past timeline is nor why intubations that are not ‘recent past’ should be excluded. Idiopathic SGS revisited Valdez Shapshay SGS is most commonly the result of mechanical trauma from endotracheal intubation. pg 690. Etiology……”emphasizing the absence of recent endotracheal intubation…”pg 691.

NOTE:  There is no timeline or research for what recent intubation is nor why any should be excluded. Endotracheal tube Cuff pressure-the need for precise measurement. San Paulo Medical Journal. Thus, pressure exerted by the cuff on the tracheal mucosa is the main cause of post-intubation sequelae. Ischemic damage of the trachea depends on the tracheal mucosal perfusion pressure and the pressure exerted by the cuff. When the cuff pressure exceeds tracheal mucosal pressure, induction of ischemia and/or necrosis is just a matter of time. Airway management Indian Journal of anesthesia, August 2005. Delayed tracheal injury is almost always cuff related….Please read paragraph on next column starting with tracheal stenosis. See also nerve injuries following pages. Simple on-line endotracheal cuff pressure relief valve, Somri. Ischemic injury of the tracheal mucosa in the endotracheally intubated patient is directly proportional to the tracheal tube cuff pressure. At a cuff pressure of 30 cm H2O, the tracheal mucosal blood flow becomes partially obstructed and at a pressure of 45 cm H2O, the obstruction to the tracheal mucosal blood becomes total, leading to tracheal mucosal damage and subsequent complications. Estimation of tracheostomy tube cuff pressure by pilot balloon palpation, Faris. Using pilot balloon palpation is inaccurate and leaves a significant proportion of patients at risk of tracheal injury. The effect of endotracheal tube inflation technique on endotracheal tube cuff pressure, Evans. Three endotracheal cuff inflation techniques were found to be used by anesthesia providers (set volume, minimal occlusive, injection and palpation)……NONE of the cuff pressures collected were found be in the acceptable range of 18-25 mmHg. Endotracheal intracuff pressure in the ED and prehospital setting, Svenson. Measurement of intracuff pressure is simple and inexpensive and should be done whenever a patient is intubated. Does body mass index predict tracheal airway size? D’Anza, Knight. Conclusions: Our study indicated a trend toward smaller airways as body mass index increased. This information should help medical professionals avoid the tendency to use a larger tube to secure the airway of an obese patient….prevent future airway injuries. Prediction of optimal endotracheal tube cuff volume from tracheal diameter and form patient height and age, M Shibasaki Nakajima. Optimal cuff volume was better estimated from tracheal diameter and patient height and age from the manual palpation method. pg Quality improvement in anesthetic practice—incidence of sore throat after using small tracheal tube, Al-Qahtani. The use of small tube….minimizes incidence of POH/POST Dimensions of the Normal Human Trachea, Breatnach. Table 2 page 906. Tracheal diameter (mm) range (age 30-80) Coronal Females 9-24 Males 11-26 Sagittal Females 7-26 Males 11-30. Please compare this with the outer diameter of the routine size of ETTs! Size of endotracheal tubes in women, Jaensson. In conclusion, the use of ETT size 6.0 instead of 7.0 in women reduces sore throat as well as discomfort from a sore throat… 

The size of endotracheal tube and sore throat after surgery, Hu. …the smaller size 6.0 was associated with a lower incidence of postop hoarseness in the pacu. Long-term results after 110 tracheal resections, Godenhard. The aetiology of stenosis was mainly postintubation injury. Note: How many of these could have been prevented if proper cuff inflation and perfusion was used? The Hoarse Patient: Asking the Right Questions, Kim. Surgical History: One important fact to remember is that any surgery requiring an endotracheal tube or laryngeal mask airway can lead to hoarseness by causing vocal cord immobility…but sometimes it is due to pressure-induced neurapraxia to the RLN. Incidence: Risk Factors for Adult Laryngotracheal Stenosis, Koshkareva, Gaughan. The reported incidence of LTS secondary to endotracheal intubation ranges from 1% to 11%. See page 207 last paragraph. See page 208 last paragraph. Directions from the ETT manufacturers:  “WARNINGS Cuff inflation by “feel” alone or using a measured amount of air is not recommended because resistance is an unreliable guide during inflation. Intracuff pressure must be closely monitored with a pressure-monitoring device. Do not over-inflate cuff. Ordinarily, cuff pressure should not exceed 25 cm H2O. Over-inflation can result in tracheal damage…” Adverse reactions listed by the manufacturer include development of dense or diffuse fibrosis invading the entire glottic area, replacement of the trachea wall with scar tissue, subglottic annular cicatricial stenosis and tracheal stenosis, fibrin deposition, rupture of the trachea, ulcerations exposing cartilaginous rings and formation of subglottic web. Patient story from today, Jan 19. I had a good sob fest tonight and wrote a pledge to live as I woke up in the middle of the night, 38 weeks pregnant, panicking because I feel like I’m breathing though a cocktail straw. I need to be more aggressive with my care of this disease. I cannot bury my head in the sand until I’m not living my life the way I want to anymore. I need to be able to go to the gym and find my peace. I want to be able to be there for my boys, to dance with them, to play with them, to throw them on the back of my bike and show them the city. I must be able to show them the joy and magic there is to life. I need to be able to pick up my crying toddler that just wants his mommy. I need to be able to do these things without hesitation. I don’t want to lose any more time or anymore life to this disease.

(Optional) About You

What is your role or perspective? Patient safety advocate, anesthesia provider, consumer

May we contact you if we have questions about your nomination? Yes

Page last reviewed March 2021
Page originally created January 2021

Internet Citation: Anesthesia/Complication of Endotracheal Intubation. Content last reviewed March 2021. Effective Health Care Program, Agency for Healthcare Research and Quality, Rockville, MD.
https://effectivehealthcare.ahrq.gov/get-involved/nominated-topics/anesthesia

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