Traditionally cardiac output has been estimated with thermodilution. Recently a new non-invasive device has been approved by the FDA for use in children of all ages including neonates (just 4 EKG electrodes). Primary outcome: To prospectively collect simultaneous physiologic data for all enrolled children by transferring the data from the investigators computerized anesthesia records to Excel spreadsheets and to correlate adverse events across monitoring devices.

Secondary outcomes: To determine if the device provides meaningful data in terms of an early warning of decreased cardiac output in specific subgroups of children undergoing surgery and anesthesia, e.g., neonates, trauma patients, children with congenital heart disease, those undergoing procedures with expected blood loss, those undergoing laparoscopic procedures where gas insufflation may impede venous return to the heart.

All children undergoing both elective and emergent surgery or GI endoscopy evaluation will be candidates for study. Since this is an FDA approved monitor that is approved across all age groups and since this is an additional monitor over those routinely used in the operating room and since it is noninvasive (4 EKG leads) verbal consent documented in the record has been approved by the IRB.

After informed verbal consent, either the research coordinator or a study physician will populate the cardiac output device with the child's age, weight, gender and height. For older children the required 4 EKG electrodes will be applied prior to induction of anesthesia (2 on the left side of the neck and 2 on the left chest at the level of the sternal depression; for neonates and infants one electrode can be applied to the forehead and the other to a thigh if application space is a problem). For children who are not able to be cooperative, as with most of our monitors the electrodes will be placed after induction of general anesthesia. An automated anesthesia record will continuously record heart rate, respiratory rate, oxygen saturation, systolic and diastolic pressures. The monitor will be set to perform these measurements every 1 minute. New software has been written that enables us to interface the cardiac output device with our automated anesthesia record. Thus the data from the cardiac output device will be inserted on the anesthesia record at approximate 1 minute intervals in real time. The data from the anesthesia records will later be downloaded as a unit to Excel spread sheets for later analysis. All demographic data will also be downloaded (age, weight, ASA physical status,surgical procedure) as well as blood loss and blood and fluid administered as well as drugs,significant intraoperative events, and the timing of events as they evolve. All data will be entered on a Partners password protected computer. Initially the patient's medical record number which links us to the electronic anesthesia record will be recorded as this allows us to download the data. Patient names will not be downloaded. Once the data set is completed,analyzed and locked, the medical record number will be removed so that no identifiers will remain. The data will not be shared with any other institution. Only deidentified data will remain on the final data base

Inclusion Criteria:

• All children presenting to our operating rooms for general anesthesia

Exclusion Criteria:

• Cardiac surgery, open chest procedures

neonates to teenagers