Fisher & Paykel Healthcare Ltd v Flexicare Medical Lt & Anor

For obviousness, the skilled person must approach prior art without hindsight or an expectation that it will solve the patent’s problem. A document’s failure to prohibit a proposed use does not amount to a suggestion or pointer towards it. The court must assess why the skilled person would think of making the relevant modification, not merely how it could be implemented once identified.

Long-felt need may support inventive step where the problem and the relevant materials or techniques were known for a substantial period, although it remains a secondary consideration. A simple modification or omission of features is not necessarily obvious. Claim language must be given its ordinary contextual meaning, and a feature requiring useful drying imposes a real, though unquantified, requirement.

Fisher & Paykel Healthcare Limited claimed infringement of European Patent (UK) 2 025 359 B1 concerning breathable materials in the expiratory limb of a breathing circuit to reduce condensation or “rainout”. Flexicare admitted infringement but counterclaimed for revocation.

The patent was unconditionally amended by incorporating a feature from dependent claim 3 into claim 1. The issues were claim construction, anticipation by Psaros, obviousness over Psaros, Kertzman and Inoue, and attacks based on lack of technical contribution and insufficiency.

1. Construction. A “flexible breathing tube” meant a tube sufficiently flexible to drape between patient and ventilator while maintaining gas flow without undue kinking. The tube itself had to be the expiratory limb. “Distributed over the length” required breathable material along the length of the tube, rather than merely somewhere within it. “Singular” excluded multiple flow passages. “Drying the humidified gases” required a useful degree of drying, although no quantified level was prescribed. The amended integers 1G and 1H placed the breathable material at the interface between the exhalation passage and ambient air, excluding the coaxial arrangement in Inoue.
2. Anticipation. Psaros did not clearly and unambiguously disclose every claim feature. Its dehumidifying device formed only part of the expiratory limb, or alternatively had breathable material along only part of the relevant tube, and it contained multiple flow passages. The absence of an express limitation in Psaros did not establish disclosure.
3. Obviousness. The applicable question was whether the invention was obvious having regard to the state of the art. The Pozzoli framework was useful but not mandatory, and the court could work from the claim features. The skilled addressee approached prior art without an expectation that it would provide a solution to the problem. Evidence of how an invention could be implemented did not answer why it would have been conceived.
4. Prior art. Kertzman concerned small breathable sampling tubes and gave no active pointer towards larger expiratory limbs. Psaros taught a specific compact bundle of tubes, and moving to one breathable tube along the whole expiratory limb would abandon its design philosophy. Inoue concerned coaxial anaesthetic circuits whose purpose was passive humidification of inhaled gas; converting it into a biaxial expiratory limb would require recognising and exploiting drying as a different objective. None of those modifications was obvious without hindsight.
5. The long-felt problem of rainout and the known limitations of heaters and water traps supported the conclusion, particularly as no one had previously adopted the claimed solution despite the availability of relevant materials. The lack-of-technical-contribution and insufficiency attacks failed, subject to the evidential squeeze having performed the work described in the judgment.
6. The patent, as amended, was valid and the defendants infringed. Amendment was allowable. The form of order, costs and any permission to appeal were adjourned for further hearing.