V. Ray Bennett

V. Ray Bennett (1922 – 1996) was an American engineer

Bennett’s contributions to respiratory medicine resulted in saving thousands of lives during the Polio epidemic.

His introduction into the medical scene started with his BR-X2 ventilator developed during WWII and allowed for the delivery of intermittent positive pressure ventilation to pilots in unpressurised aircrafts at high altitude.

The Bennett Valve – a flow sensitive valve devised in 1944 – formed the core for generations of ventilators that followed. Indeed, after the war, Bennetts’ attention was brought to circumnavigating the problem for prolonged ventilation in Polio patients at the Los Angeles County Hospital. This resulted in a multitude of inventions outlined below.

The name Bennett still occupies a well-grounded presence in the medical setting and continues to provide respiratory equipment for hospitals world-wide. What started as a small project to help patients in a local hospital suffering from Polio has now become an international company, today known as the ‘Puritan-Bennett Corporation.’


Biography
  • Born on August 5, 1922 in Balden, Mississippi
  • 1940s – founds Bennett and Associates Ventilator Company in Santa Monica XA
  • 1945 – applies for patent for an oxygen valve that allows pilots to fly at higher altitudes without developing anoxia. The valve works by providing intermittent positive pressure ventilation. It is incorporated into the Bennett Research X2 ventilator which is introduced during the mid-1940s and used to deliver IPPV to patients in respiratory failure
  • 1948 – applies for patent for a ‘Respiratory Facial Mask’; devises the Bennett positive pressure respiratory attachment (BPPRA) which converted the negative pressure ventilator of Drinker’s tank respirator to a combined positive and negative pressure ventilator to meet demand for increasing artificial ventilation from a growing polio epidemic. [US2867210A]
  • 1949 – introduces the Bennett TV-2P ventilator. This is later adapted for use with a compressed gas cylinder in the 1950’s and dubbed the ‘Bennett Tank Model
  • 1956 – applies for patent for a ‘Respiratory Mouthpiece’ which improved upon the simple mouth piece to provide a better fitted mask that was also better tolerated by patients [US2857911A]
  • 1957 – applies for patent for Respiratory ventilation meter which allows for accurate determination of respiratory volumes and titration of patient ventilation [US2787999A]
  • 1960s – the Bennett PV-3P is introduced. This model varies from the TV-2P by being pedestal mounted and using piped in oxygen or air compared to the ‘tank’ (cylinder) mounted TV-2P.
  • Other adaptations of the original Bennett respirator during this time period include the Bennett AP-4 (incorporated a compressor by NF Beasley and became a popular unit for home therapy), Bennett AP-5 (incorporated a humidifier), Bennett BA-4 and Bennett PR-2.
  • The most significant development of this decade was the Bennett MA-1 volume Ventilator which virtually replaced the iron lung. It was volume cycled and had a constant flow generator. It incorporated a flow sensitivity trigger which could be adjusted and made ventilation more comfortable for the patient and reduced ventilator-patient asynchrony. This opened up options for mechanical ventilation to now include assisted-ventilation, controlled-ventilation and combined ‘assisted-controlled’ ventilation or what would be called SIMV mode today.
  • It is unclear at what point Bennett had no further input in the development of ventilators; generations of ventilators have since followed the MA-1 which bear the name of the original innovator including the 700, 7200, 560 series, the Puritan-Bennett 840 and 980 ventilators.
  • Died on July 30, 1996 in West Memphis, Crittenden, Arkansas

Medical Inventions
Bennett Ventilator and Bennett Oxygen Valve

Originally designed and developed for use in WWII, the Bennett oxygen valve [US2483722A] was an important component of an oxygen delivery system – the BR-X2 resuscitator – which provided intermittent positive pressure ventilation to pilots in unpressurised aircrafts at higher altitudes.

Bennet Respirator
Bennet Respirator

It was later adapted into the early ICU ventilators (TV2P, PR-A, PR-2, AP-4, AP-5) bearing his namesake, The Bennett Ventilator where it was used to facilitate patient breathing or control ventilation where respiratory effort was absent or diminished.

The valve functions by means of a pressure gradient and gravity. At rest, the valve is closed due to gravity. During inhalation, a negative inspiratory pressure is generated which forces the valve open and gas flows from the ventilator to the patient. As downstream pressure rises, flow gradually slows until gravity exceeds pressure from gas flow causing the valve to close and ending the breath.

The earlier generations of Bennett ventilators were primarily used for respiratory emergencies, tracheotomy or to deliver bronchodilators to patients with chronic lung disease. They were not suitable ventilators for prolonged IPPV. With a growing Polio epidemic and increasing need for respirators, an adaptation was later developed by Bennett and his team called the Bennett positive pressure respirator attachment (BPPRA). This attachment could be fitted onto the Drinker’s tank respirator to augment the minute volume delivered and was powered by the same motor driving the Drinker Respirator.

In this way, both negative and positive pressure ventilation could be applied; the former via the action of the Drinker respirator and the latter via the intratracheal route where PPV could be delivered either through a mask covering the nose and mouth of the patient or through a tracheotomy. The total negative pressure generated in the tank could thus be reduced and a greater tidal volume achieved.

The patient could also be taken out of the Drinker Respirator for short periods of time and maintained on only IPPV which provided greater ventilation than NPV could alone. Bennett later devised a rotary cam for the Drinker machines so that the pressure patterns could be better adapted to be more ‘physiological desirable’ – this meant a longer inspiratory flow time, slower and steady rate of pressure rise and an initial rapid pressure release during expiration followed by a prolonged expiratory phase.


Bennett Ventilation Meter

There has been need for a respiratory ventilation meter in the care of poliomyelitis patients, especially in the cases of such patients requiring confinement within a respirator, the function of which is the artificial inducement of respiration over long periods of time during which it is imperative that proper O2 and CO2 values be maintained in the blood

United States Patent Office 1951

Bennett’s solution to this problem was the Bennett Ventilation Meter – A gas flow meter used as an accessory to artificial respirators (not limited to Bennett models) for determining volume of breathing. It had incredibly low resistance and low inertia characteristics that allowed for accurate volume measurements and thus a means to titrate and efficiently control patient ventilation.


Bennett Respiratory facial mask

Bennett applied for a patent in 1948 for his invention ‘the respiratory facial mask.’ [US2540567]

Its innovation was based on the need for ‘a comfortable, and yet tightly fitting mask…in cases involving pressure breathing such as encountered in resuscitation, high altitude flying and in positive and intermittent positive pressure breathing.” It found clinical use in the treatment of acute respiratory distress caused by pulmonary oedema, asthma and cardiac conditions.

The facial mask was designed to provide a tight seal around the nose and mouth with pressure equally distributed across the areas of contact to minimize discomfort and pressure areas; prevent gas escape from within the mask; minimize dead space and thus volume of gas rebreathed; and lastly be able to be easily disassembled for ease of cleaning. The facial mask also included auxiliary ports to allow for the passage of surgical instruments when the mask was in use.


Other inventions
  • Humidifier attachment for the BPPRA
  • Oxygen signal warning device when oxygen supplies were low
  • Respirator pressure warning signal
  • A rotatory cam adapter for the Drinker respirator to allow for a more uniform inflation and better alveolar aeration at more physiological pressure patterns
  • An air-pressurising unit
  • A respiratory facial mask akin to NIV today
  • Oxygen catheter for tracheotomy tubes
  • Improved tracheotomy tubes, adaptors, suctioning equipment and respirator collar 
  • Beverage dispensing apparatus…[US2132011A]

Major Publications

US Patents


Controversies

The V in “V Ray” has alternate affiliations in official documentation:

  • VOID – 1940 – SSN application US
  • VAID – 1930 US census
  • BOYD – 1940 US census
  • VOYD – 1944 – First marriage certificate
  • VIVIAN / VIVIEN – US Patent office – 1948 onwards

References

Biography

Eponymous terms


[cite]


eponym

the person behind the name

Emergency registrar at Sir Charles Gairdner Hospital, Perth

Associate Professor Curtin Medical School, Curtin University. Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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