Estimated weight and height of critically ill patients: how reliable are these values in acutely admitted patients?

Introduction

Patients' weight (W) and height values (H) are often unknown on acute admittance to the ICU. In the present study we investigated: (a) whether estimated W&H are in agreement with W&H values given by patients/relatives, and estimated H is in agreement with measured H; and (b) whether body mass index (BMI) and H influence estimated W&H values.

Methods

One hundred consecutive acutely admitted patients (from whom pre-admission W&H were unknown) were included. W&H were recorded from medical/nurse ICU records ('estimated W&H'). Afterwards, patients or close relatives were asked for pre-admission W&H ('actual W&H'). In addition, H was determined with a tape measure ('measured H'). Patients were divided into four BMI (calculated from actual W and measured H) groups and four height groups. The mean difference was calculated to assess bias between both methods. Ranges of 95% limits of agreement were calculated to assess agreement between both methods for individual patients. Statistics were by regression analysis.

Results

(a) The mean difference (95% confidence interval) between actual and measured H was 0.9 (0.3–1.4) cm. The mean difference between estimated and measured H was 1.0 (-0.2 to 2.3) cm. The 95% limits of agreement were -4.6 to 6.4 cm and -10.1 to 12.2 cm, respectively. The mean difference between estimated and actual W was 1.8 (0.7–2.9) kg. The 95% limits of agreement were -9.3 to 12.9 kg. (b) See Table 1 for data of agreement between estimated and actual W for BMI subgroups. See Table 2 for data of agreement between estimated and measured H for height subgroups.

Table 1

Table 2

Conclusions

Estimated W&H match actual W and measured H of acutely admitted ICU patients very well. W estimation is more variable for the highest BMI group.