After all of the sample sets had been tested, the mean air flow for each product was calculated and used for comparison.
Two-way ANOVA with repeated measures was used, with models of catheters as the random factor, and the three suction pressures as fixed factors. Post hoc multiple comparison analysis was performed using the Tukey test when differences were found by ANOVA. A probability value < 0.05 was considered significant.
The PDU mean flow rates achieved at various water pressure suction levels appear in Table 1. Multiple statistically significant differences and areas of similarities are noted. There is nearly a fourfold variation from the PDU with highest flow (Argyle Aqua-Seal) and the PDU with the lowest flow (Ar-gyle Sentinel Seal). The Atrium Ocean 2002, Argyle Thora-Seal III, and Argyle Aqua-Seal provide the highest flow rates, and the units are statistically similar at — 10 cm H2O and — 20 cm H2O of suction. The Argyle Sentinel Seal provides the lowest flow rates and was statistically different from all other PDUs at both — 10 cm H2O and — 20 cm H2O of pressure. The Pleur-evac A-6000, Pleur-evac SAHARA, Atrium 3600, and Atrium 3612 provide intermediate flow rates. Statistical assessment of those PDUs (n = 4) producing — 40 cm H2O of pressure demonstrates that each model is significantly different from each other (Table 1). Click Here
The accuracy (mean percent error) of the PDUs tested using the directions of the manufacturers regarding external suction titration appears in Table 3. Multiple interdevice differences in accuracy are significantly different but likely not of clinical significance. Focusing on the PDU — 20 cm H2O setting frequently incorporated in practice, three major findings are noted when following manufacturer instructions.
Table 3—Accuracy of Pressures
|PDUs||Suction Level, cm H2O|
|— 10||— 20||— 40|
|Atrium Ocean 2002||4.4 ± 0.5||4.6 ± 2.2||No — 40 setting|
|Atrium 3600||8.6 ± 5.7||7.8 ± 4.1||4.3 ± 2.6|
|Atrium 3612||4.8 ± 1.8||15.5 ± 5.0||6.8 ± 0.5|
|Aqua-Seal||NTf||0.2 ± 0.4||No — 40 setting|
|Thora-Seal III||— 9.4 ± 2.1||— 0.8 ± 1.0||No — 40 setting|
|Sentinel Seal||0 ± 0||0 ± 0||No — 40 setting|
|Pleur-evac A-6000||8.8 ± 6.1||4.2 ± 2.7||— 2.7 ± 0.6|
|Pleur-evac SAHARA||3.6 ± 3.5||4.8 ± 2.0||— 2.3 ± 1.6|