Product Development

Musings on Perfect Cadence

17 April 2012 | Team EACPDS


In an earlier blog we talked about the Lean concept of Cadence in organic terms as a heartbeat.  And then we moved out of the comfort of that pat analogy to suggest that other periodic organic processes might serve as a better analogy of cadence in Product Development in consideration of its extended cycle times. Today let’s move back to the analogy of the heartbeat and explore the concept of Perfect Cadence.

If we look at takt time on a production line as a two beat cycle — in one cycle the line advances, in the other the value adding tasks are executed – the heartbeat and our circulatory flow do serve as clarifying models for the Lean elements of Cadence and Flow.

Heartbeats have been in the news recently with the minor dustup over the suspicions of privilege in Dick Cheney’s successful heart transplant.  Below that opinionated noise there is a far more interesting story, and one that has caused my Lean head to spin — continuously — and to muse.  This other story begs the question of what would happen to the relationship of Cadence to Flow, and to our heartbeat analogy if there were no driving beat but rather continuous flow.

Prior to his heart transplant, Dick Cheney had an LVAD (left ventricle assist device) implanted to help support his failing heart and to keep him alive until a candidate heart could be found.  There are over 10,000 heart disease patients who now have one of these LVADs embedded.

The development and adoption of artificial hearts have been constrained by the rapid wear and tear on the implanted mechanical pumps, as well as by the difficulties of supplying power to the devices. The hundred days of life extension given to Barney Clark by the Jarvik 7 heart in the 1970’s set a course for medical engineering research, but the goal of a natural life with an artificial heart has remained unfulfilled.  Because of the practical limitations of artificial hearts, they have been used exclusively as devices to prolong life while patients waited for an available heart for transplant.

In the 1980’s, a doctor-engineer was inspired by an experience he recalled. A decade earlier on a volunteer mission to Africa, he had observed how water was pulled from wells by an Archimedes Screw, essentially an auger in a pipe. His inspiration and subsequent research led to the development of heart devices that moved blood not by pumping, but by means of compact turbines. Early fears that the rotating blades of the turbine would do damage to blood cells were allayed and this technology became the basis for LVADs.

LVADs are not intended as artificial hearts, but rather as ‘crutches’ for diseased hearts.  Because of their compact technology they provided mobility and freedom from hospitalization for patients awaiting transplant. Astonishingly, LVADs also demonstrated the ability to help reverse heart disease apparently in the same way a crutch relieves the burden on a leg and lets it heal.  But even greater astonishment awaited as the LVAD patient population grew and flourished.

In 2003, a patient from Central America came to the United States and was fitted with an LVAD. Communicating through a language barrier, he misunderstood the instructions for him to return frequently.  Upon release from the hospital, he disappeared. A year later, he returned for a checkup and explained that he had not returned sooner because he felt so great.  During his physical, astonishingly, he had no pulse.  His heart had given out entirely and he was being kept alive solely by the circulation provided by his implanted turbine.

Since that experience, an artificial heart based upon dual turbines has been developed and has been implanted successfully into a small number of patients as a treatment of last resort.  For now, those patients thrive and there is optimism that research has embarked on a path to a practical, long lasting artificial heart.

The circulation that results from these turbine-based artificial hearts gives continuous flow (Perfect Flow?) but no pulse, no cadence.  The critical value-add process of gas exchange in the lungs can be accomplished as the blood flows continuously. So does Perfect Cadence result from the absence of the no-value-added-but-necessary half of our two part cycle? Is it achieved when we are able to provide all necessary value contributions under the condition of continuous flow?  I think in theory it is, but as I try to visualize this in practice the only image I can summon is Lucille Ball laboring and stuffing her face at the candy factory.

Cadence is often a conscious feature.  We consciously create cadence to regulate workflow.  This enabling control feature also carries a cost, and the cost is that it keeps us from Perfect Flow.  If Perfect Cadence is that which enables Perfect Flow, then the approach to Perfect Cadence is the cadence that results as the duration of the no-value-added-but-necessary part of the cycle approaches a limit of zero.  This may not exist in the organic model that we choose to apply to our knowledge work, but it likely has conceptual value in areas like production where, like in the world of medical devices, both organic and mechanical models apply concurrently.