PImax = maximum inspiratory mouth pressure (also termed NIF = negative inspiratory force) - see video above

• Is an index of inspiratory muscle strength (Black 1969)
• Is a routine procedure in many pulmonary function laboratories
• Hautmann et al in 2000 published the mean PImax (kPA)
  • for men (N=248) to be 9.95 kPa
  • for women (N=256) to be 7.43 kPa
• "strongly dependent on the skill of the technician" (may account for 5%- 12% variation) and "the motivation of the patient"
• strongest correlation in results were for sex and age, but also height/weight/BMI and different lung function parameters

References

Hautmann H, Hefele S, Schotten K, Huber RM: Maximal inspiratory mouth pressures (PIMAX) in Healthy Subjectes – what is the lower limit of normal. Respir Med. 2000 Jul; 94(7):689-93

Black LF, Hyatt RE. Maximal respiratory pressures: normal values and relationship to age and sex. Am Rev Respir Dis 1969;99:696-702