The gods we worship

The gods we worship

Breathing proves difficult. For the entirety of her previously healthy thirty years, breathing was subjugated to unconscious control – an automated background process. However, a severe flu infection lands Pam in the intensive care unit, and she requires an advanced form of life support known as extracorporeal membrane oxygenation (ECMO). ECMO takes over the oxygenation process that Pam’s diseased lungs can no longer perform. Deoxygenated blood is removed from Pam through a large catheter in her vein, it is circulated through a machine which performs the oxygenation outside of her body (hence extracorporeal), and then the oxygenated blood is delivered back into Pam’s body.

About Extracorporeal Oxygenation

Although the concept of extracorporeal oxygenation has been postulated for centuries, ECMO procedure as we know it is an extension of the cardiopulmonary bypass machines used in cardiac surgery. ECMO was first studied outside of the operating room as a life support tool for adults in respiratory failure in the 1970s. The first clinical trial comparing conventional life support (i.e. mechanical ventilation) to ECMO found disappointing results, with survival rates below 10% in both groups1. This closed the doors to widespread adoption of ECMO in the adult critical care world. There was renewed interest in ECMO in the midst of the 2009 influenza epidemic; case reports and observational studies showed encouraging results with ECMO use2. That same year, the CESAR trial (the largest clinical trial of ECMO at the time) was published; in this trial, patients with respiratory failure were randomized to either mechanical ventilation or transfer to a hospital with ECMO expertise3. There was increased survival in patients who were transferred to the ECMO center. However, almost a quarter of the patients transferred to the ECMO center were never actually placed on ECMO; thus, many physicians questioned whether transfer to a center with advanced expertise itself was the explanation for the survival benefit rather than the use of ECMO4. EOLIA, the latest clinical trial, was terminated early and joined the collection of inconclusive trials5. This pattern is seen often in medicine: a new therapy is tested in multiple clinical trials and fails to show consistent efficacy. We have seen this pattern with the Swan Ganz catheter, corticosteroids in sepsis, various vasopressors in shock, and many other diagnostic and therapeutic modalities. Eventually, physicians divide into camps of believers and non-believers.

As physicians, we turn to physiology, basic and translational science, and clinical studies and articles for answers to medical dilemmas – such as, would ECMO or conventional life support give Pam a better chance at surviving this hospitalization. However, even an exhaustive review of the medical literature would not result in a precise answer. Medicine is an imperfect science littered with gaps in knowledge. Physicians fill these gaps consciously and unconsciously in daily clinical decisions. We then explain away these bridged gaps as the “art of medicine”, “experience”, or “intuition”, but rarely do we acknowledge the role of our underlying belief system. Belief is a powerful force in medicine. In 1847, Dr. Semmelweis proposed routine hand washing to decrease obstetric mortality, an idea contrary to medical belief of the time. He was denounced by the medical community, and hand disinfection did not garner acceptance for another 20 years. Fortunately, our lag time between research findings and clinical implementation is now only 17 years6,7. Belief perseverance exists, and it is difficult to change doctors’ practices: we unquestioningly accept dogma pedaled to us by our mentors, which we then preach to our trainees. There are intensivists amongst us who believe in the Swan god, cardiologists who worship the dopamine deity, and devotees who use only lactated ringer – all of us view scientific research through the lens of confirmation bias.

This is not to condemn all belief when practicing medicine. Without an arbitrary belief system, physicians risk descent into therapeutic nihilism. Our clinical work demands that we make decisions in the absence of complete information. However, we can benefit from conscious exploration of the beliefs in addition to the science and heuristics we apply in our decisions. Conscious assessment of our belief system can help us display transparency in our decision making process to residents and medical students, so they are not left blindly worshiping a false god. Further, mindfulness in our decision making can highlight the gaps in our personal as well as communal clinical knowledge. On a personal level, this will encourage us to seek out evidence in the literature. As a community, this will encourage medical research to continue filling the information gaps in the slow asymptotic march towards completion.

My prayers to the ECMO gods pay off. Pam’s lungs recover and she eventually leaves the intensive care unit. In time, we believers may convert the non-believers into having faith in ECMO, or we may collectively discover a more benevolent god of advanced life support. We may one day finally put the Swan god to rest, or he may resurrect with renewed fanaticism. Perhaps the intensive care unit will be populated by a new generation of worshipers of an angiotensin or vitamin C god. As long as medicine remains an imperfect science, physicians will continue to fill the gaps with the gods we worship.

 

The potential sites for ECMO catheter placement. Adapted from: Finney, S.J., 2014. Extracorporeal support for patients with acute respiratory distress syndrome.

 

Patient with ECMO outflow catheter in internal jugular vein and inflow catheter in femoral vein.

 

References

  1. Zapol WM, Snider MT, Hill JD, Fallat RJ, Bartlett RH, Edmunds LH, Morris AH, Peirce EC, Thomas AN, Proctor HJ, Drinker PA. Extracorporeal membrane oxygenation in severe acute respiratory failure: a randomized prospective study. Jama. 1979 Nov 16;242(20):2193-6.
  2. April I. Extracorporeal membrane oxygenation for 2009 influenza A (H1N1) acute respiratory distress syndrome. Jama. 2009;302(17):1888-95.
  3. Peek GJ, Mugford M, Tiruvoipati R, Wilson A, Allen E, Thalanany MM, Hibbert CL, Truesdale A, Clemens F, Cooper N, Firmin RK. Efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR): a multicentre randomised controlled trial. Lancet (London, England). 2009 Oct 17;374(9698):1351-63.
  4. Wallace DJ, Milbrandt EB, Boujoukos A. Ave, CESAR, morituri te salutant!(Hail, CESAR, those who are about to die salute you!).
  5. Combes A, Hajage D, Capellier G, Demoule A, Lavoué S, Guervilly C, Da Silva D, Zafrani L, Tirot P, Veber B, Maury E. Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome. New England Journal of Medicine. 2018 May 24;378(21):1965-75.
  6. Balas EA, Boren SA. Yearbook of Medical Informatics: Managing Clinical Knowledge for Health Care Improvement. Stuttgart, Germany: Schattauer Verlagsgesellschaft mbH; 2000.
  7. Westfall J, Mold J, Fagnan L. Practice-based research – “Blue Highways” on the NIH roadmap. JAMA 2007;297:403–6.
  8. Finney, S.J., 2014. Extracorporeal support for patients with acute respiratory distress syndrome.