الفهرس 
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Abstract
SUMMARY
Mechanical ventilation is a therapeutic intervention that supports or replaces spontaneous breathing and thereby supports adequate oxygenation of body tissues. Hemodynamic monitoring plays an important and central role in the management of critically ill patients. Hemodynamic monitoring aims to guide medical management, to prevent and /or treat organ failure, and to improve the outcomes of patients (Güner & Kutlutürkan, 2022).
The backrest position is an elevation of the head of the bed at degrees (0-30-45). The effect of adopting these position degrees in critically ill patients have been extensively investigated as a potential means of preventing ventilator-associated pneumonia (VAP), decrease hospital stay, and decreased morbidity and mortality. Hemodynamic changes occur with postural therapeutic positioning is a core component of critical care nursing to optimize ventilation and perfusion and to promote effective pulmonary gas exchange (Mezidi & Guérin, 2018).
Aim of the study:
This study aimed to assess the effect of different backrest positions’ degrees on hemodynamic stability of mechanically ventilated patients.
Research hypothesis:
Implementation of different backrest positions degrees (0 - 30-45) will change hemodynamic status of mechanically ventilated patients.
Research Design:
A quasi experimental design was used to achieve the aim of the present study.
Study Setting:
The present study was conducted in ICU at Blebies-Central – Hospital Al-sharqia.
Subjects:
A purposive sample of 40 patients on mechanical ventilators admitted to ICU was selected according to certain inclusion criteria.
Tools of data collection:
The tools used in this study were patients’ assessment tool, mechanically ventilated patients’ parameters and hemodynamic status assessment tool.
Tool 1:-Patients’ assessment tool:
It was designed by the investigator and written in English language after reviewing current related literatures (Wang et al., 2016; Anchala, 2016; Katz et al., 2018) to assess patients’ demographic and clinical data, It was composed of two parts;
Part 1: Patients’ demographic characteristics: It was concerned with assessment of demographic characteristics of the patients under study as patients’ age, gender, marital status, educational level, and occupation.
Part 2: Patients’ clinical assessment: It was concerned with assessment of patients’ clinical data such as present medical diagnosis, past medical history, Glasgow coma scale, gastrointestinal assessment, fluid and electrolyte assessment, integumentary assessment, diagnostic tests such as complete blood count, liver function test, renal function test.
Gastrointestinal assessment:
It involved examination of abdomen and abdomen content; during gastrointestinal nurses’ assessment would use the technique of inspection, auscultation, percussion, and palpation which included normal, bowel sounds, hyperactive, hypoactive, diarrhea, constipation and vomiting. (Jarvis, 2016).
Tool 2:- Mechanically ventilated patients’ parameters and hemodynamic status assessment tool:
It was designed by the investigator and written in English language after reviewing the related literatures (Brindle et al., 2013; Anchala et al., 2016; Farsi et al., 2020) to assess patients’ ventilator parameters, and patients’ hemodynamic status, it was composed of two parts as the following:
Part 1: Ventilator’s parameters assessment:
It was concerned with the assessment of the ventilator parameters among the studied patients, it included; duration of mechanical ventilation (hours) from the time of intubation to the implementation of backrest positions, mode of mechanical ventilation as pressure controlled ventilation (PCV), volume controlled ventilation (VCV), synchronized intermittent mandatory ventilation (SIMV), tidal volume (ml), positive-end expiratory pressure (PEEP), peak airway pressure (p max), and flow. It was obtained from patients’ files and mechanical ventilation setting.
Part 2: Patient’s hemodynamic assessment parameters;
1- Cardiovascular assessment: It was concerned with the assessment of patients’ cardiovascular status such as; heart rate, blood pressure, main arterial pressure, central venous pressure, and capillary refill, fluid and electrolyte assessment. It was measured by the investigator 30 minutes after each position; it was categorized as the following table.
2- Respiratory assessment: It was concerned with the assessment of the patients’ respiratory status such as; respiratory rate, rhythm, color, oxygen saturation, chest sound (crackles, strider, rhonchi, and wheezing), hypoxemia, and lung compliance.
Hypoxemia
Hypoxemia was defined as PaO2/FIO2 ratio of 300 mmhg or less. P” represents PaO2 (arterial Po2) from the ABG. ”F” represents FIO2 –the fraction (percent) of inspired oxygen the patient (40 % oxygen = FIO2 of 0.40) How to calculate the P/F ratio: PaO2/FIO2 P divided by F = P/F (Palanidurai et al., 2021).
Hypoxemia severity score was classified as:
o 300 – 201 mild hypoxemia
o 200 – 100 moderate hypoxemia
o ≤ 100 severe hypoxemia
Lung compliance
Is a measure of the lung’ ability to stretch and expand in clinical practice it is separated into two different measurements, static compliance and dynamic compliance static compliance represents pulmonary compliance during periods without gas flow, such as during an inspiratory pause.
It can be calculated with the formula;
C stat = VT / P plat – PEEP
where
VT = tidal volume, Pplat = plateau pressure, PEEP = positive end – expiratory pressure.
Compliance ≥ 80
60 – 70 ml / cm H2O
40 - 59 ml / cm H2O
20 to 39 ml / cm H2O
≤ 19 ml /cm H2O2
Results can be summarized as the following:
Concerning demographic characteristics of the studied patients; 40.0% of them were 60 years old or more with the mean age 54.95±1.23. As well, 70.0% were males. Also, 75.0% were married and almost 32.5% had secondary education. In addition, 70.0% didn’t work. Besides, 50.0 %live in urban areas. Regarding the clinical assessment of the studied patients, 37.5% respectively were suffering from DM and hypertension. Furthermore, 42.5% were smokers. The mean heart rate of the studied patient was S.D= 83.80±17.15.
In addition, the mean of their systolic and diastolic blood pressure was S.D= 130±16.4 and S.D= 82±3.9, respectively. The mean respiratory rate of the studied patient is S.D= 23.87±3.72. Also, 42.5% had crackles chest sound. Moreover, the mean Glasgow coma scale total score of the studied patient was S.D= 8.30±2.55. Besides, 25.0% of studied patients had abdominal distension and constipation respectively. As well, the mean weight and height of the studied patient was S.D= 77.77±22.3 and 164.60±23.69, respectively. 47.5% of studied patients had pale color. Additionally, the mean of PaO2 was S.D= 71.9±17.11.
Pertaining to mechanically ventilated patients’ parameters assessment, the mean of duration of mechanical ventilation (hours) from the time of intubation was S.D= 84.15±14.6. Regarding mode of mechanical ventilation, 72.5% of them were on synchronized intermittent mechanical ventilation. Moreover, there was a highly statistically significant difference between the studied patients’ cardio-vascular assessment at post 0ᵒ, 30ᵒ and 45ᵒ degrees of backrest positions as regard heart rate, blood pressure systolic, main arterial pressure and peripheral pulse.
In addition, highly statistically significant difference was found as regard blood pressure diastolic and central venous pressure. Additionally, there was a highly statistically significant difference between the studied patients’ respiratory assessment at post 0ᵒ, 30ᵒ and 45ᵒ degrees of backrest positions as regard respiratory rate and oxygen saturation. Moreover, there was a statistically significant positive correlation between patients’ capillary refill and their age at post 30ᵒ and 45ᵒ degrees. In addition, there were highly statistically significant negative correlations between patients’ age and their heart rate, systolic and diastolic blood pressure, main arterial pressure and peripheral pulse at post 30ᵒ and 45ᵒ degrees.
As well, there was a statistically significant negative correlation between patients’ central venous pressure and their age at post 30ᵒ and 45ᵒ degrees. There was a highly statistically significant positive correlation between patients’ hypoxemia and their age at post 30ᵒ degrees. Besides, there were highly statistically significant negative correlations between patients’ age and their respiratory rate and lung compliance at post 30ᵒ and 45ᵒ degrees and so hypoxemia at post 45ᵒ degrees. Additionally, there was a statistically significant negative correlation between patients’ oxygen saturation and their age at post 30ᵒ and 45ᵒ degrees.
Conclusion:
In light of the current study, it can be concluded that, implementation of 45 degree backrest position is associated with improvement of hemodynamic stability of mechanically ventilated patients and this reflected on patient outcome and short ICU length of stay.
Recommendations:
Based on the findings of the study results, the following recommendations were made:
1- Encourage nurses in intensive care settings to apply 45 degree head of bed elevation for mechanically ventilated patients’ and involved in practice guideline for critical care nurses.
2-Posters, and simple illustrations about importance of 45 degree head of bed elevation for mechanically ventilated patients.
3-Develop simplified and comprehensive booklet for critical care nurses including basic knowledge and practices regarding hemodynamic stability for mechanically ventilated patients during head of bed elevation 45 degree.
4-Backrest elevation should be decided individually for each patient according to patient’s responses, including cardiovascular and hemodynamic parameters, and systemic oxygenation.
5-There is a need for further studies with larger sample sizes and longer duration investigating the comparative effectiveness and safety of various levels of head of bed elevation to reveal the optimal, safe, and effective degree of semi-recumbent positioning for well-defined patients populations.
6-Further studies should be performed to evaluate other factors affecting homodynamic stability for mechanically ventilated patients.