Biomedical Engineering Reference
In-Depth Information
referred as peristaltic pump) could be used to gently provide continuous flow. The
first roller pump was patented in 1855 by Porter and Bradley and was hand oper-
ated. E. E. Allen modified the first roller pump in 1877 and named it the “surgical
pump.” In 1891, C. H. Truax, who also distributed and promoted the Allen pump,
developed the first double roller pump. However, these suffered from the problem
of blood leakage along the roller circuit. Subsequently, several researchers includ-
ing American surgeon Michael E. DeBakey refined the roller pump design. De-
Bakey recalled in an interview that the information available in the medical library
in Tulane University was not helping in redesigning the pump and he had to go to
an engineering library to get more information on pump design. These interactions
helped in improving the design of hand-cranked roller pumps for better usage in
blood transfusion and other applications including dialysis.
American folk hero Charles A. Lindbergh is partly credited for the develop-
ment of the heart-lung machine. Years after his pioneering transatlantic flight,
Lindbergh teamed up with a vascular surgeon, Alexis Carrel, to find a way to
put oxygen into the blood stream. A primitive oxygen exchange device was made,
confirming the possibility of using machinery for the function of the lung. John
H. Gibbon, Jr. developed the first clinically successful heart-lung machine in 1937
with the help of research technician Mary Hopkinson, who later became his wife.
Gibbons found that a pulsing flow, like that produced by the heart, was not nec-
essary. Using a spinning hollow cylinder into which the blood was trickled, they
employed centrifugal force to spread the blood in a layer thin enough to absorb the
required amounts of oxygen, which were fed in under pressure. Partially replacing
the circulation between the heart and the lungs, he managed to keep a cat alive for
four hours. This experimental machine used two roller pumps with the capacity to
replace the heart and lung action of a cat. He discovered that simply passing the
blood through the external artificial circuit caused death in less than 12 hours from
multiple small blood clots. To remove these blood clots, a fine metal mesh filter
was incorporated in the circuit. After World War II in 1946, Gibbon persuaded
the chairman of International Business Machines (IBM) and engineer Thomas J.
Watson to give financial and technical support to improve the heart-lung machine.
Along with five IBM engineers, Gibbon and Watson invented an improved machine
that minimized red blood cell death and prevented air bubbles from entering the
circulation using continuous suction. When this device was tested on dogs, it re-
sulted in a 12% mortality rate.
In 1945, Clarence Dennis, an American physiologist at the University of Min-
nesota, built a modified Gibbon pump that consisted of a nest of vertically revolv-
ing stainless steel cylinders mounted over a revolving funnel in which the blood,
oxygenated on the walls of the cylinders, was collected. During this time, Den-
nis also attempted to use Kolff's dialysis machine. Nevertheless, the new pump
permitted a complete bypass of the heart and lungs during surgical operations of
the heart. However, that machine was hard to clean, caused infections, and never
reached human testing. Viking O. Bjork, a Swedish physician who later became
popular for Bjork-Shiley mechanical heart valves, invented an oxygenator with
multiple screen discs that rotated slowly in a shaft, over which a film of blood was
injected. Oxygen was passed over the rotating discs and provided sufficient oxy-
genation for an adult human. Bjork, with the help of a few chemical engineers, one
