Respiratory variation of intra-abdominal pressure: indirect indicator of abdominal compliance?
Respiratory cycle-related variations in intra-abdominal pressure were specifically investigated, quantified and shown as linearly increasing with end-expiratory intra-abdominal pressure; this phenomenon could be explained by patients' abdominal compliance status. Supine posture should be an important consideration in specific patients affected by intra-abdominal hypertension.
Compared with pre-paid business replies, stamped envelopes did not produce a statistically significant increase in response rate to this patient survey. However, the response gain of the stamped strategy (4.9%) is similar to that demonstrated in a Cochrane review (5.3%) of strategies to increase response to general mail surveys. Further studies and meta analyses of patient responses to mail surveys via stamped versus pre-paid envelopes are needed with sufficient power to detect response gains of this magnitude in a patient population.