A prospective study of serial noninvasive measurement of cardiac output (CO) during the 1st spontaneous breathing trial (SBT) to identify failure to wean associated with cardiac insufficiency.
Patients intubated for >24 hrs were weaned according to institutional protocol. Prior to the 1st SBT a noninvasive cardiac output device, NICO© (Philips Respironics, Murrysville, Pa., USA) was connected to the ventilator circuit. Three measurements were made prior to, at the beginning of, and at the end of the SBT.
50 patients were tested: mean age 61±18yrs; 47% male;mean APACHEII 22±7; main reasons for intubation were Sepsis (33%) and ARDS (15%). 30% of patients failed the 1st SBT (F). In comparison to patients who passed (P) the 1st SBT those who failed had similar age (69±14 v.63±19ys;p=0.24),gender (61 v.49%female; p=0.39),and APACHEII score (23.1±6.7 v 1.2±7.5;p=0.34). The VD/VT measured prior to the SBT was higher for patients who failed (0.53±0.11v.0.47±0.08; p=0.035). The CO and Pulmonary Capillary Blood Flow (PCBF) were similar for both groups prior to weaning (P:5.8±2.2 v F:5.6±2.0;p>2) and (5.3±2 v. 4.6±1.4; p>2) and at the start of the SBT (6.0±2.3 v.5.9±1.8;p>2) and (5.5±2.5 v 4.8±1.5;p>2) respectively. The CO end of the SBT was higher for patients who passed (7.3 ± 3.1v.5.6 ± 2.0;p=0.03) the PCBF were also higher but not statistically significant (6.2±2.9v. 5.1±1.6;p>0.2). Patients who failed the first SBT and were unable to augment their CO passed subsequent SBTs after optimizing interventions while demonstrating an increased CO compared to their failed trials (5.5±1.1v.6.1±0.81;p=0.02). Interventions included aggressive diureses, dobutamine or NTG drips but not part of the study protocol. The patients who failed their 1st SBT had increased mean weaning time (3±2v.1±3d;p=0.028), ICU LOS (16±9v.9±7d;p=0.001), MV time (9±6v.6±4d;p=0.13) and hospital LOS (38±31v.30±54 d;p=0.04).
A significant proportion of patients failing their 1st SBT have associated cardiac insufficiency as identified noninvasively by serial measurement of cardiac output.
Early non-invasive method for identification of patients failing SBT due to cardiac insufficiency is feasible and may allow goal directed interventions to expedite the weaning process.
Maged Tanios, No Financial Disclosure Information; No Product/Research Disclosure Information