The Altitude Metaphor: Clinical ESRD Perspectives Explained Through Aviation

This blog post was co-authored by Dr. Davidson and Billy Nolen on June 17, 2021.
The Altitude Metaphor:  Clinical ESRD Perspectives Explained Through Aviation

This blog originally appeared on the Kidney Academy site.

Controversy surrounds the establishment of planning, placement, and management of dialysis access. The dialysis access conundrum is magnified by the many treating specialties viewing the best path to a solution through different lenses. Issues surrounding specialties are best illustrated by the Indian parable of five blind men examining an elephant and coming to vastly different conclusions as to what they find.


Figure 1. The expression "elephant in the room" is a metaphorical idiom in English for an important or enormous topic, problem, that is obvious and on everybody’s mind, but no one wants to talk about.

The dialysis access clinical structure affects decision making and outcomes. To illustrate different delivery systems, let us use an aviation altitude metaphor.

The critical decision points include the dialysis type and modality selection, timing of access placement and who places the access. The lack of and difficulty of performing randomized studies with multiple confounding factors, in the heterogeneous and rapidly changing ESRD population demographics, only partly explains the dialysis access conundrum. Add to this the rapidly developing device technology and the wide spectrum of the professional experience, bias, and socio-economic forces to make the dialysis access multilayered and complex.

A Patient-Centered Dialysis Access Decision-Making Algorithm

The issue is not who places the access but who does it right, every time, to everyone, and everywhere.1 Another confounding factor is the widely different professional experience with which we make decisions about the best treatment of our fellow human beings. This makes the decision-making process complex and is related not only to the skills and knowledge level of the individual, but to his or her specialty and professional maturity reflecting the level of training. This is illustrated in the Dreifus Scale of Professional Development 2, (Table 1).

The initial Dreifus Scale had 5 categories, with expert being the highest. The expert level of competence is about 10,000 hours of practice or about 10 years of work professional experience – a concept popularized in Malcolm Gladwell’s book BLINK. 3

Table 1. Dreifus Scale of Professional Development

  1. NOVICE (Plays by the rules, low situation awareness (SA), low judgment)

  2. ADVANCED BEGINNER (Follows guidelines, limited SA, all things equally important) 

  3. COMPETENT (Long-term vision, planning, accountable, routine procedures)

  4. PROFICIENT (Holistic views, priorities, decisions made easy, some intuition, perceives deviations from normal, invited lecturer)

  5. EXPERT (Intuitive grasp of situation, analytic: “I don’t follow rules, I make them”).

  6. MASTER (Source of new knowledge and new ways, unique style, likes surprises)

  7. PHILOSOPHER (Pre-Alzheimer)

(The connotations in Table 1 are added to project onto the medical profession)

A professional can progress from level 1 to level 7 much faster if he or she embodies the growth mindset, a collaborative and synergistic spirit, and always makes decisions with the #1 priority: the patient in the center.

The dialysis access clinical structure takes many forms, affecting decision making and outcomes. To illustrate different delivery systems, let us use the Altitude Metaphor as pictorial representations to show the interaction of the various elements. The five altitudes for describing RRT on different levels are as follows:

I. Still at the Airport

A health care worker in a supporting role is limited to view only on the ground. From the aviation metaphor, he or she has not even left the airport, or at best is still taxiing with no runway in sight.  This scenario represents very limited options for the patient (Figure 2).

The goal is to give the reader a progressively wider view of dialysis access. So, let us elevate ourselves to see a bigger picture of delivering renal replacement therapy (RRT)—with global ambitions.

arial photo of land

Figure 2. In case of limited involvement such as a service role or being a student with limited understanding of complex clinical problem solving, is illustrated in this DFW airport image, representing Dreyfus level 1.

II. The Bird's View

In this scenario, the access options may include peritoneal dialysis catheter placements and wrist native vein AVFs. The moral of this situation is that if you do not perform a certain services or procedure—then refer the patient to someone who does. There is a subliminal and unacceptable disconnect between PD and hemodialysis, which deprives patients of the most appropriate first-time dialysis mode in up to 50% of cases. An (unacceptable) reason not to consider PD is sometimes “I am a vascular surgeon; I don’t do PD."

What is a Bird | Information About Birds

Figure 3. The dialysis access bird view represents limited resources, skillsets, and professional bias as to what should or can be done

III. The 5,000 ft View

The dialysis access conundrum is further magnified by the several specialties seeing dialysis access through different lenses. This higher level of view takes a greater focus on the patient’s overall experience over a longer time to include consideration of additional RRT modalities.

private jet

Figure 3. This 5,000 ft level of dialysis access includes peritoneal dialysis

The next level of an access program includes peritoneal dialysis – this scenario is often associated with a transplant program.

IV. The 10,000 ft View

On the next altitude level, we can see an entire city where all access procedures including transplantation are available. This setting usually represents a large hospital or an academic institution with resources and professionals meet criteria for a comprehensive RRT program. (Table 2). Smaller communities must seek outside sources for services e.g., transplantation.

Commercial Aircraft - Airbus

Figure 4. At 10.000 feet altitude a whole city can be viewed. This metaphor includes all aspects of ESRD care from dialysis to transplantation.

V. Supersonic Speed at 60,000 ft

If we decide to fly even higher or at 60,000 feet at supersonic speed, this image paraphrases the national level of ESRD and dialysis access planning, now including disease prevention measures and transplant and national safety planning. The 60,000 ft level metaphor represents our national U.S. health program (Figure 5). National planning and decision-making are, in principle, not different from local planning. Of course, a national scope has broader impact with consequences for many more individuals. The DOQI guideline is an example of the level of altitude metaphoric national planning. 4

advanced aircraft

Figure 5. The supersonic airplane at 60 K feet represents the most sophisticated technological jetliner ever built and represents the national view of RRT

VI. The Failing Mode

Airplane disasters are stark reminders that even the best and most sophisticated designed (healthcare) system can fail when human errors intercept and rules are not followed (Figure 4). Systems designs (the blunt end) are typically there for safety to prevent or make mistakes impossible for the individual operator (the sharp end).

airplane failure

Figure 6. This image of the burning Air France Concorde flight 4590 at takeoff at Orly airport in Paris 2000 was a direct consequence of bypassing a safety measure in the interest of saving time.

VII. The International Space Station – 350,000 miles up

We can “fly” even higher. The International Space Station (ISS) symbolizes the global metaphoric approach to ESRD and RRT.

How do you keep a space station clean? - BBC Future

Figure 7. The International Space Station (ISS) represents a great human achievement in technology in how to plan, coordinate, and monitor activities.

The international partnership of space agencies operates the ISS. As the ISS is an amazing technical achievement, there is ample evident it has contributed to world peace—by requiring trust and cooperation between the world’s leading powers to achieve and this mission in space. Clearly the ESRD healthcare global community could do something similar, not even having to leave the airport!

Table 2. Features or Programs Associated with RRT

  • Prevention starts in childhood (involves patient education, cultural norms, focus on healthy habits to prevent progression to ESKD in the 1st place!)

  • A kidney transplant is the best dialysis machine

  • PD is the most optimal/appropriate/right first-time dialysis mode (in 30-40% of patients)

  • If there is poor vascular anatomy for an AVF, consider a Graft

  • The early cannulation graft is a tool to avoid CVC and TCVO

  • Move proximally as needed: the distal-first concept is not valid in the elderly

  • In co-morbid situations, consider pre-emptive Proximal Arterial Inflow (PAI) to:

    1. Prevent steal

    2. Avoid CVC

  • Palliative (medical) treatment only—end-of-life situations

What an effective ESRD algorithm looks like

The algorithm below considers reasonable options and available support systems, individualized for patients for the stage of their disease progression.  There are gray areas between these choices including patient-specific wishes. One serious fact is that, on a global scale, treatment with dialysis or a kidney transplant to stay alive, is available to only 10% of people who need this treatment to live. A subliminal message of the tabulation is that ignoring transplantation, PD, and or grafts will exclude up to 50% of ERSD patients from the optimal RRT at any given time. A comprehensive global online training and clinical meeting forum was held in June 2020, at the start of the COVID-19 pandemic, to support the multidisciplinary dialysis access team in reaching the best decisions for individual patients. 5 Their conclusions were that:

  • Medical professionals’ roles are to prevent disease. Informed and understanding patients (or population) is not a reality in most societies. The role of patients’ responsibility in prevention of kidney disease is a subject for another editorial.

  • The kidney is the best dialysis machine. Few patients on dialysis treatment (2.7 % in the US/year) qualify for a transplant/year for lack of acceptance criteria and shortage of organs.

  • There are several compelling reasons to make Peritoneal Dialysis (PD) the appropriate first-time dialysis modality is qualifying patients—even in case of excellent vascular mapping results.

  • Patients who disqualify for PD should get an AVF directed by Ultrasound mapping anatomy.

  • Grafts come in with benefits in this algorithm. For example, with the early cannulation ability Central Venous Catheters contact time is shortened or eliminated.

  • Grafts are also suitable in the elderly patients using the upper arm, where vessels are larger, and associated with low risk for steal or hand ischemia.

  • Consider a pre-emptive proximal arterial inflow (PAI) in the elderly and co-morbid patients to avoid steal and the use of CVC.

  • For patients with ESRD who are at the end stage of life, CVC only may the right dialysis access—or no access, meaning medical treatment only is the right option for your fellow human being.


1. Davidson I, Gallieni M, Saxena R, Dolmatch B. A patient centered decision-making dialysis access algorithm. J Vasc Access. 2007; 8:59-68.

2. Dreyfus SE, Dreyfus HL. “A five-stage model of the mental activities involved in directed skill acquisition” 1980. Available from: = ADA084551. Accessed Jan 09, 2016.

3. Gladwell M. Blink. The Tipping Point: How Little Things Can Make a Big Difference;2000; Little Brown and Company, New York, ISBN 0-316-31696-2

4. Lok CE, Huber TS, Lee T, et al. KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update. Am J Kidney Dis. 2020;75(4S2): S1-S164. doi: 10.1053/j.ajkd.2019.12.00

5. (viewed on June 1, 2021).

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