The University of Kansas
Respiratory Care Education

Cub

The Bear Cub is an electrically and pneumatically powered, continuous flow, time triggered and cycled pressure or flow controller. The Cub has CPAP and IMV modes. The Test position checks the LED lamps and batteries. The knobs below the Airway Pressure Monitor are the Loss of PEEP/CPAP and Low Inspiratory Pressure alarms. These alarms can be set by turning the alarm setting up until the visual indicator and audible alarm activates, and then slowly decreasing the alarm level until the audible ceases. Press VISUAL RESET to remove the alarm indicator light.
The PEEP/CPAP and peak inspiratory Pressure (PIP) Limit controls are located below the FIO2 knob. The flowmeter in the center determines the continuous flow through the circuit. Below the visual RESET and alarm SILENCE buttons are the controls knobs to set Inspiratory Time and Ventilator Rate. A toggle switch by the Rate control allows a range of 1 - 75 or 76 - 150 breaths/min. The manual breath button is only functional in CPAP mode and is limited by the PIP limit setting.

There are LED displays for Inspiratory and Exhalation Time, I:E Ratio, Mean Airway Pressure, and Ventilator Rate. Below the displays are the red indicators with audible alarms for Low Inspiratory Pressure, Loss of PEEP/CPAP, and Prolonged Inspiratory Pressure. Prolonged Inspiratory Pressure activates if the airway pressure stays 10 cm H20 above baseline for more than 3.5 seconds. The next alarm down is the Ventilator Inoperative alarm. The six conditions causing a Vent Inop alarm are fail-to-cycle, electrical power failure, inaccurate inspiratory time, control panel malfunction, prolonged ON time, and timing circuit failure.
There are also alarms for low air or oxygen inlet pressures and rate/time incompatibility. The rate/time incompatibility alarm will activate if the ventilator rate and inspiratory time settings allow less than 0.25 seconds for exhalation.

A backup mechanical Pressure Relief is located on the back panel and held in place via a locking ring. With the patient wye blocked, turn the PIP limit on the front all the way up before loosening the locking ring and adjusting the Pressure Relief. When the pressure is adjusted, usually at 30 cm H20 or 5 - 10 cm H20 above the PIP, hold the pressure relief while tightening the locking ring. The backup pressure pop-off should be checked and set before connecting the ventilator to the infant.
The pressure relief is located on the inspiratory outlet where tygon tubing connects the ventilator to the humidifier. The expiratory limb of the ventilator circuit from the patient connects to the Exhalation Valve. Below the exhalation valve is the exhalation manifold which contains a venturi. The venturi helps prevents inadvertent PEEP across the exhalation valve. The proximal airway tubing connects to an air filter whose directional arrow should point away from the ventilator. Also located on the back are the circuit breakers and the high pressure hose connections for Oxygen and AIR.

There are many brands of humidifiers that could be used with the Cub. At KUMC we use the RCI Concha-Pak with a duel heated wire circuit. There are two temperature probes (not shown) with the heated wire circuit. One probe connects at the humidifier outlet and the other at the proximal airway, located about 14 inches from the patient wye. The proximal temperature sensor is located away from the patient wye to prevent heated environments, heat lamps, etc, from affecting the sensor. The set temperature is servo controlled and maintained.
The top section labeled "1" contains the ON/OFF toggle switch, the temperature SET knob, the DISABLE/ENABLE toggle switch, and the temperature alarm. The bottom section labeled "2" contains the heated wire controller. The Concha Column is labeled 3 and the water reservoir is "4".

When the humidifier is first powered ON, the temperature alarm is temporarily DISABLED and the yellow indicator illuminates. When the LED readout reaches 27 C the temperature alarm may be manually ENABLED by the toggle switch. Otherwise, the temperature alarm will automatically be enabled after 20 minutes. At that time, if the temperature is still below 27 C for some reason, the audible temperature alarm will sound. Once enabled the temperature alarm will activate if low temperatures or high temperatures (over 40 C) occur. With high temperatures, the toggle switch must be moved to the RESET position. The temperature SET control has an adult (A) and pediatric (P) guide setting. The humidifier should not be powered on without gas flow through it.
The bottom section "2" adjusts the temperature of the heated wires. The maximum temperature difference between the humidifier and the heated wires is 3 degrees C. To make the heated wires cooler, turn the center control toward the rain cloud. If there is too much condensation in the tubing, turn the control toward the sun. The relative humidity is determined by the temperature difference between the humidifier heater and the heated wires. Beads of moisture should ALWAYS be present at the patient wye to ensure adequate relative humidity. If the patient wye is dry, adjust the heated wire control toward the rain cloud. Inadequate relative humidity can cause drying of secretions and mucous plugging.
The indicator on your right illuminates when the wires are heating. The indicator on your left is the RAINOUT ALERT which will illuminate when the heated wires are not powered. The wires are not heated under the following conditions: if the humidifier temperature is less than 30 C, the proximal airway temperature is greater than 38 C, or if the humidifier is hot (>38 C) and the proximal airway temperature is cool (< 27 C).

RC Ed WebMaster