Case No. IP-2019-000196

109.Hamilton relies on the combination of the Tehrani Paper and US 268 to render the invention of claim 45 obvious. The Tehrani Paper includes a footnote which refers to US 268 and for that reason Hamilton says that the two documents would be read together by the skilled person.110.The Tehrani Paper discloses an arrangement which combines two closed-loop systems. One controls oxygenation by varying FiO2 by reference to automatically measured PaO2. There is no automatic measurement of PEEP or any disclosure of maintaining the PEEP/FiO2 ratio within a prescribed range. The other system controls ventilation according to the invention claimed in US 268. 111.US 268 is concerned with a method for automatic ventilation control. Data representing carbon dioxide and oxygen levels in the patient’s exhaled breath, the patient’s lung elastance, lung air viscosity and barometric pressure, plus optionally the metabolic rate ratio when the patient is in exercise, are fed to an algorithm which generates output values for breathing frequency and ventilation.112.Although there is no automatic measurement of PEEP, the specification of US 268 mentions the possibility of manual measurement:“In the manual control mode, the minute ventilation and the frequency of every breath or alternatively the positive end expiratory pressure ‘peep’ is specified for the respirator by an operator. The end expiratory pressure may also be continuously monitored by additional sensors through the reserved channels of the A/D converter. A system reset is required to restart the controller.”113.Professor Rees took the view that a skilled person reading the Tehrani Paper would note the footnote reference to US 268 and adopt its teaching for automatic ventilation control. He or she would be aware that oxygenation management solely by FiO2 control has its limitations, would therefore also think of adjusting PEEP and in fact would be prompted to do so by the passage in the specification just quoted. Further, since FiO2 measurement is automated, it would be obvious to automate the measurement of PEEP as well. Professor Rees acknowledged that the skilled person would know that there could be downsides to automating PEEP control, such as the risk of applying excessive pressure, but also know that there would be upsides. Next, the skilled person would know about the ARDSnet publication and thus be aware of fixed values for FiO2 and PEEP pairings. He or she would accordingly have adopted such fixed values. Finally, it would then be obvious to implement a system which ensured PEEP and FiO2 were balanced within a prescribed range of ratios.114.To my mind, Professor Rees’ reasoning is an example of an argument of lack of inventive step developed by setting out a series of steps by which the teaching of a piece prior art can be adjusted to arrive ultimately at the invention of the patent in suit. Each of the steps may be individually obvious but the fallacy of the argument is that performing all of them, without exception, may not have been obvious. Professor Rees’ evidence does not say, expressly, that performing all of these steps would have been obvious at the priority date. To the extent that this is implied, Professor Rees does not say why adopting all of the steps collectively would have been obvious. I am not satisfied that it would have been.115.Claim 45 does not lack inventive step over the Tehrani Paper and US 268.