GE Cardiocap 5 Service Manual

Measurement Parameters 
6.2 Measurement principles for hemodynamic parameters 
6.2.1 NIBP 
NIBP (Non-Invasive Blood Pressure) is an indirect method for measuring blood pressure. 
The NIBP measurement is performed according to the oscillometric measuring principle. The cuff is 
inflated with a pressure slightly higher than the presumed systolic pressure and deflated at a speed 
based on the patients pulse. Data are collected from the oscillations caused by the pulsating artery. 
Based on these...

Cardiocap/5 Technical Reference Manual 
6.2.5 Invasive blood pressure (N-XP option) 
A catheter is inserted into an artery or vein to measure invasive blood pressure. The invasive pressure 
setup—consisting of tubing, a pressure transducer, and an intravenous bag of normal saline all 
connected together by stopcocks—is attached to the catheter. The transducer is placed level with the 
heart and electrically zeroed. 
The transducer is a piezo-resistive device that converts the pressure signal to a...

Measurement Parameters 
A general limitation of the above pulse oximetry principle is that due to the use of only two 
wavelengths, only two hemoglobin species can be discriminated by the measurement.  
Modern pulse oximeters are empirically calibrated against fractional saturation (SaO2frac) or against 
functional saturation (SaO2func) as shown below: 
SaO2frac = HbO2/(HbO2 + Hb + Dyshemoglobin) 
SaO2func = HbO2/(HbO2 + Hb). 
Functional saturation (SaO2func) is less sensitive to changes of...

Cardiocap/5 Technical Reference Manual 
 
Figure 6-4. Comparative light absorption 
The sensor’s photodetector collects and converts the light into an electronic signal. Since O2Hb and 
HHb allow different amounts of light to reach the photodetector at the selected wavelengths, the 
electronic signal varies according to which light source is “on” (red or infrared) and the oxygenation of 
the arterial hemoglobin. The oximeter uses this information to calculate the relative percentage of 
O2Hb and HHb....

Measurement Parameters 
A CO-oximeter typically uses four or more wavelengths of light and calculates reduced hemoglobin 
(HHb), oxyhemoglobin (O2Hb), carboxyhemoglobin (COHb), and methemoglobin (MetHb). Therefore, 
pulse oximetry readings and CO-oximetry readings will differ in situations where a patient’s COHb or 
MetHb are increased. Increased patient COHb leads to falsely increased SpO2 in all pulse oximeters. 
Datex-Ohmeda enhanced pulse oximetry uses functional calibration, which is represented...

Cardiocap/5 Technical Reference Manual 
6.3 Measurement principles for airway gases, spirometry, and NMT 
6.3.1 CO2, N2O, and agent measurement 
TPX is a side-stream gas analyzer that measures real-time concentrations of CO2, N2O and anesthetic 
agents (Halothane, Enflurane, Isoflurane, Desflurane, and Sevoflurane). The TPX analyzer identifies 
anesthetic agents or mixtures of two anesthetic agents and measures their concentrations. It also 
detects mixtures of more than two agents and issues an alarm....

Measurement Parameters 
 
Figure 6-8. Infrared absorbance of AAs 
To achieve measuring accuracy, numerous software compensation parameters are individually 
determined for each TPX during factory calibration. 
6.3.2 O2 measurement 
The differential oxygen measuring unit uses the paramagnetic principle in a pneumatic bridge 
configuration. The signal picked up with a differential pressure transducer is generated in a measuring 
cell with a strong magnetic field that is switched on and off at a frequency...

Cardiocap/5 Technical Reference Manual 
6.3.3 Patient spirometry measurement 
In mechanical ventilation, breaths are delivered to the patient by a ventilator with a proper tidal volume, 
respiration rate (RR), and inspiration/expiration ratio in a time determined by the ventilator settings.  
Patient Spirometry monitors patient ventilation and displays these parameters: 
• Expiratory and inspiratory tidal volume (TV) in ml 
• Expiratory and inspiratory minute volume (MV) in l/minute 
• Expiratory...

Measurement Parameters 
Compliance and airway resistance 
Compliance tells how big a pressure difference is needed to deliver a certain amount of gas into the 
patient. Compliance is calculated for each breath from the following equation: 
ComplTVexp
PPEEPiPEEPeplat
=−−
 
The airway resistance, Raw, is calculated using an equation that describes the kinetics of the gas flow 
between the lungs and the D-lite flow sensor. The equation states that the pressure at the D-lite can at 
any moment of the breath...

Cardiocap/5 Technical Reference Manual 
6.3.4 NeuroMuscular Transmission (NMT) measurement 
The NMT feature provides peripheral nerve stimulation and response measurement that supports 
electromyography EMG. You can also use the Cardiocap/5 NMT feature as a nerve locator for regional 
nerve blocking with a regional block cable, however, in this case there is no response measurement. 
Nerve stimulation 
There are three NMT stimulus modes: Train of Four (TOF), Double Burst 3,3 (DBS) and Single Twitch...