Journey Through Ventilation

My journey into ventilation should read like a chapter from "Alice in wonder land' but I am sure that the educative content based on my interactions with world stalwarts would be useful to the reader. Neonatal ventilation is about 40 years old. My own perception of ventilation 20 years back after I completed my post graduation was shrouded in mystery and awe. I was introduced into this art in 1998 by Dr. Simbrunner in Vienna, an associate of Gregory who designed CPAP in 1970's. Gregory demonstrated its remarkable effect on neonatal ventilation by recruiting FRC (Functional Residual Capacity). He wanted me to be perfect with CPAP, when I was anxious to learn ventilation. After 20 years with ventilation I found that CPAP is the center point of ventilation on which a tidal volume is superimposed. The foundation of setting up optimal FRC or CPAP or PEEP, used interchangeably, is paramount in avoiding lung morbidity.

EARLY 1990's
The heat and the nerve wracking training in ventilation was imparted by Dr. Elizabeth John Head of Newborn Division Westmed Hospital Sydney in 1989. Her meticulous nature taught me in 2 years all I needed to known in the care of a neonate beyond 24 weeks gestation. She was central to the development of neonatal specialists in India by virtue of her overseas training programme where in we could work as registrars equivalent to the Australian counter parts . My colleagues Dr. P.M.C. Nair , Dr.Lalitha Krishnan, Dr.Diwakar, Dr. Arun Desai, Dr. Umesh Vaidya, Dr. Ashish Mehta, Dr.Sheela Aiyer to name a few have done very well in the advancement of ventilatory care in India since the 1990's. Dr. Elizabeth was very dogmatic with End expiratory pressure and would use superlatives if we were to toy with PEEP/CPAP. Eventually I came to know it is the most important parameter in ventilation. The inspiratoty time in this period was 0.8 - 1.0 sec and invariably most babies developed BPD. 'Lower ' PEEP and high PIP strategy to improve the mean airway pressure also contributed to the above. Currently we know volutrauma is the reason for BPD.

MID 1990's
I had visited the U.S to advance my ventilator strategy and understanding of neonatal ventilation. I underwent training in High Frequency Oscillation (HFO) in the University of Iowa under Dr. Edward Bell. Where all babies were treated with HFO . my understanding of PEEP / CPAP underwent a quantum change. "High" PEEPs were applied to the lungs of critical babies and they did well. Even in the west in that era HFO was not a standard therapy in most units and most specialists hit the panic button by saying "HFO has failed". This was due to low PEEP strategy. This exposure Dr. Bell formed my concept of application higher PEEP in all complex lung disease. In fact I had lost my "PEEP phobia". Due to Dr. Bell I was able to successfully applied HFO to all babies who required a mean airway pressure more than 13, with out failure, and rescuing critical babies whose mean air way pressure was close to 28. These pressures would not be easily tolerated on conventional ventilators. I firmly believe that HFO is a valuable tool for rescue in the right lung with the right strategy since my application of the same from 1997

Later I visited Dr. Keith Barrington in the University of Santiago medical centre USA and on rounds he showed a blood gas value of CO2 75 mmhg and asked me "are you worried?" I said "may be" since the baby was a preterm 32 weeks. I later realized that gentle ventilation and permissive hypercapnea promoted by Dr. Jein Tin wung in mid 80's was a good concept in neonatal ventilation. Wung and Edward Bell remain my favourites to date, since my day to day management lies on higher CPAP / PEEP and gentle ventilation. Wung incidently taught me to watch the air column in the bronchus in all Xrays and do deep suction as and when indicated. The inspiratory time during this period had come down to 0.35 - 0.45 see. There was significant improvement in the incidence of BPD above 1000 grans and 30 weeks. Surfactant also contributed significantly due to the shorter duration of ventilation and lower pressures.

LATE 1990's
I visited Dr. Vidyasagar Head of Neonatology university of Chicago in 1997 and was imprseed with his unit and the training programmes. He remained my teacher and guide since then. I later met Dr. Sivasubramanium Head of newborn division Washington D.C George town university. I had a brief exposure to jet ventilation. Dr. Dhani Reddy introduced me into the fascinating world of pulmonary graphics. Then I realized based in this real time data that our inspiratory times set could still be lowered. I used as a Thumb Rule of inspiratory time 0.3 secs in preterm and 0.35 secs in term babies since 1998. I hence introduced a detailed chapter in this book on graphics.

2000 AD Our unit had a very low incidence of BPD above 650 grams due to the ventilatory strategies which evolved with time. Our CPAP application increased and I feel the optimum recruitment of FRC since birth and its maintenance by CPAP/ PEEP has lead to the decreased lung morbidity in our unit. The "shorter" inspiratoty times used also must have contributed to the decreased lung morbidity.

In 2002 our unit success with sildenafil in pulmonary hypertension was received world wide. I went to visit Dr. Martin Kessler George town university Washington and stayed in his unit for 3 weeks to learn jet ventilation. He asked me how to improve oxygenation in a complicated baby with MAS. I said "put up the PEEP". He remarked that my PEEP concepts were very advanced even for the US consultants.

I started volume ventilation in 2002 and base my ventilatory parameters on a tidal volume of 4ml/kg. I have to profess that the book will be flavored with "higher" PEEP, CPAP, gentle ventilation and volume targeted ventilation. I asked Wung on his protocol and criteria for a change. He said if your lung morbidity is rock bottom with your protocol why try to change? I hence have presented this book with modern concepts and strategy, bearing in mind our units survival of 96.3% in all babies weighing more than 650 grams, and the strategies there of. I was fortunate to be trained by the best specialists in the world, but Dr. Elizabeth John remains always close to my heart for implanting that CPAP/PEEP software into me in 1989.
EVERY VENTILATOR BREATH IS ABNORMAL Rajiv

A UNIT WHICH USES A LOT OF CPAP IS A GOOD UNIT Rajiv Back