A. Determine if Respiratory Volume Monitor (RVM) can be used during procedural sedation to adequately monitor patient's respiratory status as compared to capnograph Aims B. Compare the time of capture of respiratory events (depression, arrest, etc…) on both the RVM and the capnograph C. Compare the incidence of missing or poor quality readings between the RVM and the capnograph D. Compare RR readings between the RVM and the capnograph (during periods with adequate data quality on both devices) E. If RMV can identify respiratory obstruction. Capnography

Rationale for Proposed Research: Continuous respiratory monitoring using the ExSpiron System will be particularly beneficial to patients receiving intravenous propofol breathing spontaneously with natural airway. Assessment and management of respiratory function and early intervention when indicated is a multifaceted, complex task often complicated by the unavailability of a cohesive and continuous monitoring system to guide clinical decisions. The ExSpiron system is designed for these patients and is intended to address some of the limitations of the current generation of hospital monitors and to provide healthcare providers with continuous real-time data regarding the patient's respiratory status. Recent RVM data has shown that stratification of patients based on the MV % of predicted, prior to opioid dosing has made it possible to identify patients who are at risk for further decrease in MV and opioid-induced respiratory depression (OIRD).

1. In the spontaneously breathing, non-ventilated patient, current monitoring devices do not provide continuous, objective non-invasive, continuous real time information of important respiratory parameters such as TV, MV and RR.
2. Current monitoring of non-intubated patients mostly relies on oximetry data, subjective clinical assessment and occasionally EtCO2 measurements. In appropriate clinical settings, the ExSpiron system can provide direct quantitative measure of ventilation parameters for use in clinical assessment and trend prediction as well as response to medications and other interventions.

Inclusion Criteria:

Inclusion Criteria: patient's ≥ 20 years of age receiving intravenous sedation, or intravenous general anesthesia with propofol.

Exclusion Criteria:

Criteria: patients not able to give informed consent, Inability to place the PadSets on the thorax. Existence of an active implanted neurostimulator.

50 patients receiving intravenous propofol for sedation, or general anesthesia with natural airway and breathing spontaneously will be recruited and will give written informed consent. The RVM data collection will end when the patient is discharged from the operating room.