Background: Physicians have relied on “static” vital signs (heart rate, blood pressure, etc.) to evaluate patients despite knowing that adequate assessment of oxygen delivery depends on both the perfusion pressure (blood... [ view full abstract ]
Background: Physicians have relied on “static” vital signs (heart rate, blood pressure, etc.) to evaluate patients despite knowing that adequate assessment of oxygen delivery depends on both the perfusion pressure (blood pressure) and flow (cardiac output). Numerous studies have proven that the “vital” signs of heart rate and blood pressure do a very poor job of identifying patients’ cardiac function. Currently, consultant diagnostic studies are frequently obtained to provide this information, despite not always being available in urgent settings. Recently, new technology (ClearSight/Nexfin) has been developed and validated to provide cardiac output non-invasively, along with other flow-guided parameters (stroke volume, dp/dt, systemic vascular resistance, and stroke volume variation). This multi-phase study seeks to assess if use of this technology can facilitate preoperative assessment with an ultimate target of helping risk –stratify patients undergoing emergent/urgent procedures.
Methods: The current phase of the study is designed to evaluate the utility of the HD device in identifying patients with cardiovascular dysfunction. After IRB approval, patients seen in the preoperative clinic (either by an anesthesiology resident or a nurse practitioner) who were scheduled to undergo major surgery (defined as surgical time greater than two hours and having the potential of > 20% shifts in blood volume) were consented. After consent the patient had the HD device placed for 2 minutes for data capture and then they were surveyed regarding the level of discomfort during the study (Likert scale). The perioperative provider then performed the clinic visit and reviewed the patients medical record. The provider was then asked to quantify the patient’s cardiac dysfunction status as normal, mild, moderate, or severe. Results from the HD monitor were compared between the patients who were scored as normal/mild vs. moderate/severe. Comparisons of these multiple variables between groups were performed with one-way ANOVA with series of Scheffe’s. A p-value of < 0.05 was significant.
Results: Currently, 57 patients have been enrolled for the first phase of this project. Current results suggest that no subjects experienced discomfort while wearing the device during data capture. A total of 42 patients were identified by the preoperative provider as having normal or mild cardiac dysfunction and 15 patients were identified as having moderate to severe cardiac dysfunction. Comparisons of HD data showed that the normal/mild group had statistically significant: 1) higher average values of cardiac index (2.8 ± 0.86, 2.4 ± 0.76, p=0.003), stroke volume index (34.2 ± 7.5 vs. 32.3 ± 9.2, p=0.02), and lower average values for systemic vascular resistance index (2935 ± 859 vs. 3503 ± 847, p=0.02).
Conclusions: Preliminary data from this ongoing study demonstrated an association between HD data derived from a non-invasive device to a patient’s degree of cardiac dysfunction, as determined during their perioperative assessment. Continuing efforts on this project will ultimately evaluate the utility of this device to risk stratify patients undergoing urgent surgery.
