The most pervasive organ failure detected in critically ill patients is respiratory failure. The majority of these patients need mechanical ventilation (MV) to alleviate their work of breathing, maintain adequate gas exchange, and unburden their respiratory muscles(1). Consistent with a multinational survey involving approximately 5000 patients, the most common indications for MV are; acute respiratory failure (69%), coma (17%), chronic obstructive pulmonary disease (COPD) (3%), and neuromuscular disorders (2%)(2). Assisted MV should be used early in order to eliminate the harmful effects of controlled ventilation, particularly the development of ventilator-induced diaphragmatic dysfunction, and to facilitate rapid weaning(3). Effective MV necessitates the coordinated function of two pumps; the first is the MV, in which the settings are chosen by the clinician govern. The patient's respiratory system is the second pump, controlled by the neuromuscular system, lung compliance, and airway resistance. Presumably, these two pumps should work mutually, which is significant since synchrony between the ventilator and the patient maximizes patient comfort, decreases the work of breathing respiratory muscle fatigue, and enhances oxygenation and ventilation(4, 5).
In the 1970s, Patient-ventilator asynchrony (PVA) was described as "fighting the ventilator"(6). Sassoon and Foster defined it as a mismatch between patient-initiated breaths and ventilator-assisted breaths(7). PVA has recently been defined as the difference in inspiration and expiration timing between the patient and ventilator(8). It can also be defined as a different time, flow, volume, or pressure demands of the patient's respiratory system and MV(9). PVA risk factors are numerous, including patient-related factors such as anxiety, pain fever, and delirium. Diseases-related factors include high resistance (e.g., COPD), low compliance (e.g., ARDS), and decreased/increased respiratory drive because of central and neuromuscular disorders. Ventilator related factors as inappropriate ventilator settings of the trigger, rise time, level of pressure support, cycling, inspiratory flow, rate of respiration, tidal volume (VT), inspiratory time, and intrinsic positive end-expiratory pressure (auto-PEEP)(9–11).
It is evident that different types of asynchronies occurred in a significant percentage of patients during MV. Leite et al. (12) illustrated that chance of PVA is higher by 10% in postoperative cardiac patients, especially when initially ventilated in volume-cycled ventilation (VCV), and this risk remained high in the subsequent pressure support ventilation (PSV) phases. Zhou et al.(13) investigated the occurrence and complications of PVA. It was found that 24% of the studied mechanically ventilated patients had different types of PVA, with the highest percentage of occurrence being double triggering (13%). The second occurrence was both cycle mismatch (4%) and ineffective effort (4%); the least occurrence was delayed triggering (1%), double triggering occurred more frequently in volume cycled ventilation than in pressure cycled ventilation.
When the ventilator does not have the potential to detect patient effort, which is called trigger asynchrony, on the contrary, trigger asynchrony indicates that the patient's breathing rate is higher than the ventilator's rate, and the most ineffective efforts are detected during mechanical expiration. However, they will also occur during inspiration, ineffective trigger threshold caused by setting too high-pressure support, frequency, inspiratory time, and tidal volume(14). Reverse Trigger is often misidentified as a double trigger or auto-trigger, but it is neither. Mechanisms responsible for the reverse trigger are thoracic or diaphragmatic stretching receptors and spinal reflex(15).
Auto triggering occurs when a mechanical breath is delivered to the patient without exerting any inspiratory effort, which can be caused by a high inspiratory trigger sensitivity, air leaks in the endotracheal tube cuff, ventilator circuit, chest tube, and flow oscillations(16). Double triggering indicates two consequent inspirations with short expiratory time, where the patient triggers the primary cycle. Risk factors of double triggering are high respiratory drive, low tidal volume, neural inspiratory time(17).
Flow asynchronies imply that the delivery of a mandatory breath does not correspond to the requirements of the patient. It is classified into an inadequate flow and a high flow. The inadequate flow is caused by high rise time in pressure targeted breath, high demand diseases, such as fever, sepsis, pain, anxiety, hypoxia, and hypercarbia(18). High flow is less common and caused by low rise time in pressure targeted breath and high flow in volume targeted breath.
Cycling Asynchrony is classed into early cycling and delayed cycling. when the allotted time to the mechanical breath is not enough for the patient's inspiratory effort, the problem of early cycling occurs while delayed cycling happens when the mechanical breath has a longer time in comparison to the patient's inspiratory effort(19). The problems arise from cycling too prematurely as the patient continues to be in the inspiratory phase. Still, the ventilator has been switched to expiration, which may cause double triggering and increased work of breathing(20). Patient-ventilator asynchrony can cause a variety of unfavorable outcomes, including increased work of breathing, patient discomfort, alveolar overdistension, lung injury, sleep disorders, unnecessary use of sedation, modifying the result of weaning, as well as a more extended stay in ICU and long term MV(21, 22).Health care professionals, especially critical care nurses who are in charge of patient monitoring and care for 24 hours, should bear in mind to ensure that the patient receives suitable ventilation requirements and prevent worse outcomes related to PVA(1, 17).
Consequently, the prevention, early detection, and management of PVAs are recognized as vital actions during both invasive and non-invasive ventilation (NIV)(17, 23, 24). There are several tools to assess asynchrony. Measurement of diaphragmatic electrical activity by electromyography and esophageal pressure measurement is considered the method of choice for detecting asynchrony(18, 25). Nevertheless, they are invasive and expensive; therefore, their availability during daily clinical practice is restricted. Waveform analysis from mechanical ventilation is a non-invasive method to determine patient-ventilator asynchronies. Ventilator waveforms provide a graphical explanation of how a patient's breath is delivered. Ventilator waveforms do not necessitate extra equipment and are readily available for real-time. The ability of the health care providers, especially critical care nurses, to detect PVA timely and accurately can improve critically ill patients’ outcomes(23, 26).
Waveform analysis by visual inspection will be a reliable, non-invasive, and substantial tool for detecting patient-ventilator asynchrony(27). It is essential for ICU staff to integrate their knowledge of pulmonary physiology with adequate knowledge regarding ventilator waveform in order to be able to interpret if critically ill patients interact appropriately or poorly with the ventilator for early detection of PVAs(27–29). Since critical care nurses are the professional figure who spends the majority of their working time at the bedside, they have the chance to achieve significant participation in the timely identification of PVA. Hence, ventilator waveform analysis has been identified as a skill that needs a properly trained professional(17, 30). Consequently, the question is whether the critical care nurses can identify PVA through waveform analysis.
Up to now, the number of nurse researchers who handled the patient-ventilator interactions is limited. Enrico et al.(1) conducted a review and investigated the level of nursing skills to discover patient-ventilator asynchrony. They found that published research that assessed knowledge and skills of nurses related to the ventilator's waveform monitoring are very limited. The few available pieces of research point out that nurses rarely participate in ventilator waveform analysis(17, 30, 31). The suggested causes for this were related to multifaceted monitoring, inadequate suitable educational courses, and limited resources and instructive tools. In the end, they concluded that ventilator graphic monitoring might be a difficult practice, especially for ICU nurses. In addition, they recommended that postgraduate university courses cover the knowledge and skills needed to manage patient-ventilator asynchrony adequately.
Recently, a universal study was conducted by Ramirez et al. (32) through an online survey to investigate the main factors associated with proper recognition and management of PVA. The results revealed that proper recognition and management of PVA were associated significantly with specific training programs in MV, the number of ICU beds, and the number of recognized PVAs. Several studies were conducted on mechanically ventilated patients in Egypt. Nonetheless, no study has been conducted on this issue. Hence, this study was performed to assess the knowledge level and attitude of critical care nurses in Egypt regarding the use of ventilator waveform monitoring to detect PVA.
Aim of the Study:
The study aimed to assess the knowledge and attitudes of critical care nurses in Egypt towards the use of ventilator waveform monitoring to detect patient-ventilator asynchrony.
Research question:
- What is the level of knowledge and attitudes towards the use of ventilator waveform monitoring among critical care nurses in Egypt?
- Can critical care nurses in Egypt detect patient-ventilator asynchrony through ventilator waveform analysis?