Introduction Quadriceps rectus femoris cross-sectional area (RF_CSA) is considered a useful marker of quadriceps strength with a 20% reduction in RF_CSA observed in critically ill patients at 10 days after admission to the intensive care unit (ICU). This has clinical importance in patients following the acute critical illness episode as it is postulated that quadriceps muscle wasting reduces quadriceps muscle strength and as a consequence impairs physical activity and health-related quality of life (HRQL). We therefore hypothesised that RF_CSA would have a direct relationship with HRQL.

Method Patients were assessed within 48 h of discharge from the ICU to the ward as part of an ongoing multicentre randomised controlled trial. RF_CSA was determined using real-time B-mode ultrasonography using an 8MHz 5.6 cm linear transducer (PLM805, Toshiba Medical Systems Ltd, Crawley, UK) at a distance three-fifths from anterior superior iliac spine to the superior patellar border. HRQL was measured using the self-reported hospital anxiety and depression (HAD) scale and the short form-36 v2 (SF-36) questionnaire. Higher scores indicate better HRQL from the SF-36 questionnaire and lower scores indicate better HRQL from the HAD scale.

Results 17 post critical care patients were recruited. Mean age was 60.7±14.9 years with 64.7% (n=11) female. Mean body mass index (BMI) was 26.0±6.4 kg/m² and fat-free mass index (FFMI) was 16.8±3.9 kg/m². The correlations between RF_CSA and HRQL are shown in Abstract P71 table 1.

Conclusion RF_CSA was correlated with HRQL, including HAD scale and the SF-36 mental functioning domain, but there was no relationship with the SF-36 physical function domain and RF_CSA. Although this was an unexpected finding, it reflects the limitations of the SF-36 physical function domain to separate those patients that have a marked reduction in independent physical activity following discharge from ICU. Further studies are required to assess the relationship between muscle wasting, strength, physical activity and quality of life in these patients following critical illness.