Abstract
Airway secretions may increase in intubated patients due to the impaired mucociliary clearance, impaired cough reflex, abnormal glottic function, insufficient moisturizing, and respiratory tract infections. As with any intervention, patients should be cautiously monitored for possible complications during the endotracheal suctioning. Procedure-related changes in the cerebral and somatic tissue oxygenation, hemodynamics, and oxygen saturation can be observed in these patients. It is important to ensure maintenance of tissue oxygenation during these and other interventions performed in critically ill children. The aim of this study was to investigate the effects of the endotracheal suctioning on tissue oxygenation in patients undergoing mechanical ventilation in the pediatric intensive care unit. Cerebral and somatic near-infrared spectroscopy (NIRS) monitoring were performed noninvasively using standardized NIRS equipment as a means of monitoring regional tissue oxygenation. Vital signs, level of sedation, pain scores, and somatic and cerebral tissue oxygenation values of mechanically ventilated patients were recorded prospectively 5 minutes before, during, and after endotracheal suctioning. Cerebral NIRS measurements did not exhibit any statistically significant changes during endotracheal suctioning. Somatic NIRS levels changed significantly before, during, and after endotracheal suctioning and remained low throughout the procedure. Endotracheal suctioning is an invasive intervention that facilitates clearance of tracheal secretions and maintenance of the oxygenation and ventilation. The maintenance of the tissue oxygenation should be documented during these and other interventions performed on critically ill children. Somatic NIRS is a useful tool for monitoring tissue oxygenation during such procedures.
Keywords: endotracheal suctioning, somatic oxygenation, cerebral, near-infrared spectroscopy
Introduction
Airway secretions are frequently increased in critically ill pediatric intubated patients. Endotracheal suctioning is defined as the mechanical clearance of the secretions with a negative-pressure vacuum device in patients who have an endotracheal or tracheostomy tube. Endotracheal suctioning should be performed to ensure sufficient ventilation and airway patency according to the care and needs of mechanically ventilated patients. Airway secretions may increase in intubated patients due to the impaired mucociliary clearance, impaired cough reflex glottic function, insufficient airway humidification, and respiratory tract infections. The aspiration of the secretions, which accumulates in the airway, also decreases airway resistance and work of breathing. 1
Endotracheal suctioning may cause complications such as hypoxemia, trauma to the tracheal and/or bronchial mucosa, vagal stimulation, cardiac dysrhythmia, alveolar collapse, pulmonary atelectasis, bronchoconstriction, infection, pulmonary hemorrhage, increased intracranial pressure, and either systemic hypertension or hypotension. Regarding the complications of the procedure, sedation scores, pain scores, and vital signs should be cautiously monitored. 2 3 4
Vital sign parameters, such as heart rate, blood pressure, and oxygen saturation, which are frequently used during standard monitoring in the intensive care unit, are inadequate for monitoring tissue oxygenation. Therefore, regional tissue oxygenation is being explored as a potential solution to this important problem for critical care physicians. Near-infrared spectroscopy (NIRS) measures regional oxygenation (rSO = oxyhemoglobin/total hemoglobin) detecting both oxy- and deoxyhemoglobin signals within the venous plexus of peripheral tissues. Thus, NIRS allows for continuous, noninvasive monitoring of tissue oxygenation in a peripheral skin/tissue bed. NIRS reflects the oxygen saturation value in the tissue vascular bed, of which 70 to 80% is venous. 5
Although several studies have examined the effects of endotracheal suctioning on hemodynamics and tissue oxygenation in adults and neonates, the number of studies conducted with children are rather limited. 6 7 In this study, our aim was to investigate the effects of the endotracheal suctioning on the somatic and cerebral tissue oxygenation in patients requiring mechanical ventilation in the pediatric intensive care unit.
Materials and Methods
Twenty critically ill and intubated children, who were followed with cerebral and somatic NIRS at the pediatric intensive care unit between April 2019 and August 2019, were included in the study. All patients received midazolam and fentanyl infusion for sedative analgesia and were monitored with mechanical ventilation on pressure-controlled, synchronized intermittent mechanical ventilation with pressure support (SIMV-PSV). Patients were not given additional doses of medication. Vital signs, sedation and pain scores, and somatic and cerebral tissue oxygenation values were recorded 5 minutes before, during, and after endotracheal suctioning. The oxygen saturation, heart rate, blood pressure, and cerebral and somatic NIRS measurements were recorded for each patient during a maximum of four aspiration procedures each. The preprocedure measurement was recorded 5 minutes before suctioning, then intraprocedure measurements were recorded during suctioning and in 1-minute intervals until 5 minutes passed after the end of suctioning. The heart rate was recorded using multiparameter monitors in the intensive care unit and blood pressures were measured using a monitor with technical specifications for automated noninvasive blood pressure monitoring devices with a blood pressure cuff.
Suctioning Procedure
Closed endotracheal (ETT) suctioning system was used in our all intubated patients. The American Association of Respiratory Care Guidelines for endotracheal suctioning procedures were considered. 8 Informed consent was obtained from parents and endotracheal suctioning was applied using a Trac Care catheter which was introduced in the ETT avoiding contact with the airway and applying a negative pressure between 80 and 100 mm Hg, according to patient's age, for a maximum period of 10 seconds. The size of the closed suction catheter was selected as per the manufacturer's recommendations for each size of ETT. The suction catheter was passed to the tip of the ETT. Endotracheal suctioning should be to the tip of the endotracheal tube but never more than 0.5 cm beyond the tip of the ETT to prevent mucosal irritation and injury. Measurement of length was determined by using the centimeter markings on the endotracheal tubes and by adding the length of additional space of the endotracheal tube adapter (usually 1 cm). Routine suctioning was avoided. The patients' requirement for suctioning was evaluated by physical assessment including oxygen saturation less than 90%, presence of secretions in endotracheal tube, audible and visible secretions, and asynchrony of the respiratory pattern with the ventilator. Patients did not receive routine hyper oxygenation before and after suction. 6 7 8 9 10
Sedation and Pain Scores
The State Behavior Scale (SBS) 11 was used for the calculation of sedation scores and the Behavioral Pain Scale (BPS) 12 was used for the calculation of pain scores, as the patients were intubated and sedated in the intensive care unit. The most commonly used sedation assessment scoring tool is the SBS. The State Behavior Scale is a short form of evaluation, such as responding numerically to sound from −3 to +2, light touch, and response to aspiration. 11 The BPS is based on a sum of three items: facial expression, movements of upper limbs, and compliance with mechanical ventilation. We scored each pain indicator from 1 (no response) to 4 (full response), assuming that a relationship should exist between each score and the intensity of pain; the possible range score of BPS was 3 to 12. 12
Near-Infrared Spectroscopy Measurements
Cerebral and somatic NIRS monitoring was performed using noninvasive NIRS for the assessment of regional tissue oxygenation. Cerebral and somatic/mesenteric oxygen saturations were recorded with INVOS cerebral/somatic oximeter (Invos 5100; Somanetics Corp, Troy, Michigan, United States). After the application of three pediatric-neonatal probes (INVOS OxyAlert NIRSensors for neonates, infants, and children under 40 kg) to the corresponding sites as per manufacturer's suggestions (bifrontal for cerebral and midline below the umbilicus for the somatic-mesenteric measurements). Monitoring sites were cleaned with disinfectant wipes, and oximeter probes were applied to dry skin surface after 2 to 3 of minutes to prevent any artifacts in during monitoring. The transducer contains a light-emitting diode and two sensors at different distances from the light source. The Invos monitor calculates the regional tissue oxygen saturation which is expressed as the percentage of oxygenated hemoglobin (oxygenated hemoglobin/total hemoglobin). 13 14 All variables were stored continuously in a multichannel system.
Pediatricians who worked in the pediatric intensive care unit performed the suctioning and pediatric intensive care unit nurses collected the data during the procedure. Pediatricians who performed the endotracheal suctioning were unaware of the NIRS data. None of the patients were excluded from the study because of suction complications. The study protocol was approved by the local institutional ethics committee (June 14, 2019/89).
Statistical Analysis
All statistical analyses were performed using the Statistical Package for Social Sciences (SPSS for Windows v20.0). Categorical variables were expressed as integers and percentages. Continuous numerical measurements were given as mean ± standard deviation (SD) or median (minimum, maximum) values. Friedman's test was employed to compare the changes in numerical measurements over time for the same parameter. The statistical significance level was taken as p < 0.05 for all comparisons.
Results
Twenty critically ill children, who were intubated and monitored with the cerebral and somatic NIRS between April 2019 and August 2019, and a total of 70 endotracheal suctioning procedures, which conducted on these children, were included in the study. Fifty percent of patients were female ( n = 10), and the mean age was 59.4 ± 63.6 months (minimum = 2 months; maximum = 204 months). The underlying diseases are listed in Table 1 . The minimum, maximum, median, mean ± SD values obtained during the study are given in Table 2 .
Table 1. Hospitalization diagnosis of patients in pediatric intensive care unit.
| Patient n (%) |
|
|---|---|
| Neuromuscular diseases | 7 (35) |
| Postoperative care | 4 (20) |
| Metabolic diseases | 3 (15) |
| Infectious diseases | 2 (10) |
| Other diseases | 2 (10) |
| Respiratory diseases | 1 (5) |
| Cardiovascular diseases | 1 (5) |
| Total | 20 (100) |
Table 2. Comparison of the monitored parameters before, during, and after endotracheal suctioning ( n = 70) .
| Presuction Mean ± SD Median (minimum–maximum) |
During suctioning Mean ± SD Median (minimum–maximum) |
Postsuction Mean ± SD Median (minimum–maximum) |
p -Value | |
|---|---|---|---|---|
| SpO 2 | 97.83 ± 3.18 100 (89–100) |
96.34 ± 4.70 99 (82–100) |
98.51 ± 2.63 100 (92–100) |
0.01 |
| Heart rate (beats/min) | 133.74 ± 20.92 138 (83–174) |
140.26 ± 20.35 144 (86–182) |
133.09 ± 20.85 135(75–179) |
<0.001 |
| Systolic blood pressure (mm Hg) | 106.93 ± 17.04 107 (58–152) |
109.23 ± 18.23 111 (68–148) |
105.39 ± 14.39 105 (73–139) |
0.06 |
| Diastolic blood pressure (mm Hg) | 61.76 ± 13.24 59 (26–98) |
64.00 ± 13.98 63.50 (28–92) |
61.94 ± 12.14 59.50 (34–98) |
0.28 |
| Cerebral oxygenation (%) | 72.79 ± 10.79 74.50 (46–95) |
70.94 ± 11.93 71.00 (48–95) |
73.05 ± 10.16 74.75 (50–95) |
0.12 |
| Somatic oxygenation (%) | 77.00 ± 20.77 87.00 (20–95) |
74.74 ± 21.48 85.50 (16–95) |
77.17 ± 19.98 85.50 (24–96) |
0.002 |
| Pain score | 3.23 ± 1.2 3 (0–7) |
3.71 ± 1.57 3 (0–8) |
3.17 ± 1.18 3 (0–7) |
<0.001 |
Abbreviations: SD, standard deviation; SpO 2 , saturation of peripheral oxygen.
The oxygen saturation did not change before and after endotracheal suctioning ( p > 0.05) but a statistically significant decrease was observed during the suctioning procedure ( p = 0.01; Tables 2 and 3 ). Likewise, the heart rate did not change before and after the procedure, but there was a statistically significant increase in heart rate during the suctioning procedure ( p < 0.001). The assessment, which was performed after determination of the normal blood pressure intervals according to the age groups of the patients, showed that there was no statistically significant change in the diastolic and systolic blood pressure levels before, during, and after endotracheal suctioning ( p = 0.06 and 0.28, respectively).
Table 3. Comparison of the monitored parameters before, and during endotracheal suctioning ( n = 70) .
| Presuction Mean ± SD Median (minimum–maximum) |
During suctioning Mean ± SD Median (minimum–maximum) |
p -Value | |
|---|---|---|---|
| SpO 2 | 97.83 ± 3.18 100 (89–100) |
96.34 ± 4.70 99 (82–100) |
0.093 |
| Heart rate (beats/min) | 133.74 ± 20.92 138 (83–174) |
140.26 ± 20.35 144 (86–182) |
<0.001 |
| Somatic oxygenation (%) | 77.00 ± 20.77 87.00 (20–95) |
74.74 ± 21.48 85.50 (16–95) |
0.006 |
| Pain score | 3.23 ± 1.2 3 (0–7) |
3.71 ± 1.57 3 (0–8) |
<0.001 |
Abbreviations: SD, standard deviation; SpO 2 , saturation of peripheral oxygen.
We also did not observe any statistically significant change in the sedation score in correlation with the suctioning procedure. On the other hand, the pain score increased significantly during the procedure ( p < 0.001) but remained unchanged before and after the procedure.
We also investigated cerebral and somatic NIRS changes during the endotracheal suctioning procedure regarding tissue oxygenation. The cerebral NIRS measurements did not exhibit a statistically significant change during the endotracheal suctioning ( p = 0.12). However, the somatic NIRS levels changed significantly before, during, and after the aspiration and remained low during the procedure ( p = 0.002). The comparative data of patients for the monitored variables before, after, and during endotracheal suctioning are summarized in Table 2 .
We observed statistically significant change in the oxygen saturation, heart rate, somatic oxygenation, and pain scores in correlation with the aspiration procedure, before, during, and after endotracheal suctioning. On the other hand, monitoring parameters were unchanged when studied before and after the procedure ( p > 0.05). We also observed a statistically significant change in oxygen saturation, heart rate, somatic oxygenation, and pain scores when analyzing before and during endotracheal suctioning. P -Values are given in Tables 2 and 3 .
Discussion
Airway secretions may be increased in critically ill pediatric intubated patients, who are monitored in intensive care units. Therefore, endotracheal suctioning is the most common invasive intervention performed in intubated patients. 15 16 17 For this reason, intubated patients should be cautiously monitored for possible complications during endotracheal suctioning. Procedure-related changes in the cerebral and somatic tissue oxygenation, hemodynamics, and oxygen saturation can be observed in these patients. Changes in tissue oxygenation and hemodynamic parameters may occur as a consequence of the aspiration procedure and the oxygen saturation can decline before and during the endotracheal suctioning. 6 18 Maggiore et al conducted a study in adults and reported decreased oxygen saturation during endotracheal suctioning. 19 In studies conducted in preterm infants, hypoxia was observed during endotracheal suctioning. 20 21 In a study of 19 patients in the tertiary pediatric intensive care unit, 28% of patients had oxygen desaturations before endotracheal suctioning and 33.7% of patients developed desaturation after suctioning. 7 During the endotracheal suctioning procedure, a statistically significant decline in oxygen saturation was detected in our patients.
During endotracheal suctioning, mechanical stimulation of the trachea, pain, and perhaps fear perceived by the patient may lead to sympathetic nervous system stimulation, and consequently, hypertension and tachycardia may occur. 22 Furthermore, changes in heart rate and blood pressure may emerge depending on changes in the intrathoracic pressure, release of catecholamines, or vagal stimulation. 19 A study conducted in neonates showed a decrease in heart rate in patients during the procedure. 23 In our study, we determined a statistically significant increase in heart rate during the endotracheal aspiration ( p = 0.01). In a study conducted in neonates, 23 no significant change was observed in blood pressure during suctioning procedure which was consistent with our findings. In another study on children, the authors reported an increase in blood pressure with suctioning. 7 The hemodynamic effects are related to cerebral and somatic hypo- or hyper perfusion; it is therefore relevant to cerebral and other organ perfusion in humans.
When compared with the other parts of the hospital, the intensive care units are unusual and frightening places for the critically ill children and their families. This depends on factors, such as the pain, fear, and anxiety experienced by patients, being in a different environment, a noisy place away from family, and being in a place with no day and night difference, which are full of invasive interventions and the presence of unfamiliar people. In children, irritants like the endotracheal tube, mechanical ventilation, nasogastric, and urinary catheters are the potential causes of pain. Sedatives relieve anxiety and induce sleep. Sedatives are used to enhance patient comfort to optimize care and for infants requiring mechanical ventilation. 3 4 11 While we did not observe any change in sedation scores, pain scores remained stable before and after the procedure but increased during the procedure. We were not able to establish pain control in spite of sufficient sedation.
Noninvasive continuous regional tissue oxygenation (NIRS) monitoring was first introduced in 1977. 24 25 Its introduction in pediatrics as a monitoring tool was in 1985 for the cerebral tissue oxygenation in preterm infants. 25 26 NIRS became a routine part of our clinical practice for monitoring cerebral and somatic oxygenation in the critically ill patients. 25 It was reported that a decline in the cerebral and somatic NIRS values is a warning that the tissue perfusion has declined in children who develop low cardiac output after cardiac surgery. 13 In a study conducted with children, an increase in the cerebral NIRS was associated with a decrease in blood pressure, and an increase in heart rate was observed during endotracheal suctioning, whereas simultaneous somatic NIRS values decreased with transient decreases oxygen saturation. 7 In another study, bradycardia and a decrease in cerebral tissue oxygenation were reported in preterm infants with low birth weight. 23 Although we did not observe a change in cerebral NIRS in our patients before, during, and after endotracheal suctioning, somatic NIRS decreased significantly during suctioning procedure.
There is no clear information regarding the distribution of pediatric NIRS values for different tissue beds in the literature. Generally, the range of rSO 2 is 55 to 80% and either an absolute drop in rSO 2 values of 50 or 20% drop from rSO 2 baseline are commonly considered as intervention trigger. 27 Kurt et al suggested that a smaller increase in ScO 2 during cooling (3 ± 2 and 33 ± 4%; p < 0.001) was associated with abnormal postoperative neurologic status. 28 In our study, we observed a statistically significant change in the somatic oxygenation correlating with the aspiration procedure before, during, and after endotracheal suctioning ( p = 0.002). On the other hand, the somatic oxygenation was unchanged when we studied before and after the procedure ( p = 0.893). There is a need for additional cross-sectional studies with control groups focused on hemodynamic and tissue oxygenation, and the long-term effects of these changes in critically ill patients. We said that statistically significantly somatic NIRS remained low throughout the procedure.
Interestingly, there was no change in blood pressure, sedation score, or cerebral NIRS parameters throughout the procedure. However, heart rate and pain score increased significantly during the postoperative period, and oxygen saturation decreased during the procedure. Nonetheless, somatic NIRS remained significantly low throughout the procedure. Therefore, somatic NIRS is a valuable tool for documenting tissue oxygen changes in critically ill patients. It appears that somatic NIRS is a more reliable guide than cerebral NIRS for following tissue oxygenation in such invasive and painful procedures. Cerebral tissue perfusion was preserved with compensatory mechanisms, whereas somatic NIRS declined as a result of the decrease in the oxygenation.
Limitations
The small sample size and the low number of aspiration procedures were the limitations of our study. There is a need for studies with larger number of patients and endotracheal suctioning procedures.
Conclusion
In conclusion, patients hospitalized in intensive care units should be cautiously monitored for the management of the complications related to suctioning procedure. The protection of the tissue oxygenation should be targeted during the interventions performed in critically ill children. Somatic NIRS may be more helpful than cerebral NIRS as a tool for following tissue oxygenation. However, there is need for further cross-sectional studies which are having control groups focused on the effects of the endotracheal suctioning on hemodynamic and tissue oxygenation and late effects of these changes in clinical status of critical ill patients.
Funding Statement
Funding None.
Footnotes
Conflict of Interest None declared.
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