Common Troubleshooting in Daily Practice

Abstract

When the ventilator alarm is triggered, sometimes the problem is easy to spot and solve. If the cause is not immediately obvious, the primary responsibility is to ensure adequate ventilation. This is a priority over diagnosis. Most troubleshooting are diagnosed by rapid clinical examination. Radiology and bedside lung ultrasound are helpful.

Most important alarms include high airway pressure, low exhaled tidal volume (VT)/minute ventilation alarm, low pressure, high frequency, low frequency, apnea, high positive end-expiratory pressure (PEEP), and low positive end-expiratory pressure (PEEP).

Causes of ventilator alarm are either ventilator related (e.g., inappropriate settings or ventilator malfunction) or circuit related (kinking in the circuit, fluid in the inspiratory limb of the circuit, disconnection in the system, or obstructed filters) or endotracheal tube (displaced, kinked, obstructed, or tube cuff leak) and patient related (airway narrowing, decreased lung/chest compliance, patient-ventilator dyssynchrony, effects of interventions, procedures and medications, or new systemic or pulmonary illness).

The first response to ventilator alarm is to disconnect the patient from the ventilator, and start manual bag-mask ventilation. If the distress resolves and the patient is easy to ventilate, it indicates ventilator/circuit problem. If the distress continues and the patient is difficult to ventilate, it indicates patient/artificial airway problem.

Check the ventilator for dysfunction and the circuit for visible obstruction, disconnection, or leakage. Check pulse oximeter reading as hypoxia can be life threatening. Check endotracheal tube position and its cuff for leakage. Assess the patient for patient-ventilator dyssynchrony.

In case of high airway pressure alarm, performing “inspiratory pause hold” maneuver to measure the plateau pressure can differentiate airway problems (resistance) from lung/chest problems (compliance).

Tension pneumothorax is a life-threatening condition, which needs rapid recognition. Although serious, it is manageable with simple clinical maneuvers, i.e., immediate needle decompression and intercostal tube insertion.

Low-pressure alarm will serve the same function of low exhaled tidal volume (VT)/minute ventilation alarms.

Rapid shallow breathing is a clinical sign of respiratory distress as it increases dead-space ventilation, metabolism, and CO₂ production.

The high-frequency alarm limit should be lowered accordingly during the weaning process, while the low-frequency limit should be adjusted accordingly with the patient’s spontaneous frequency.

The high PEEP alarm may be set at 2 cm H₂O above the current PEEP. The low PEEP alarm may be set at 2 cm H₂O below the current PEEP.

Total PEEP can be estimated by activating the “expiratory pause hold” and noting the end-expiratory pressure when it plateaus.

If a patient desaturates while on a mechanical ventilator, the same principle is applied; consider both patient causes and equipment causes. Check “if the patient is ventilating” before going on to a more detailed examination.

Venous return is largely determined by intravascular volume and venous tone. Profound hypotension may occur in patients on positive-pressure ventilation due to auto-PEEP, drugs used for intubation or sedation, and less common, but life-threatening, tension pneumothorax.

Management of hypotension on mechanical ventilation includes fluid administration, vasopressor infusion, and management of the cause.