Application of prone position ventilation in ventilation strategies for patients with COVID-19

Abstract

BACKGROUND:

Patients with coronavirus disease 2019 (COVID-19) have been shown to die mainly due to disease-induced acute respiratory distress syndrome (ARDS). Prone position ventilation (PPV) is an important ventilation strategy in the management of patients with ARDS.

OBJECTIVE:

To investigate the application of PPV in ventilation strategies for patients with COVID-19.

METHODS:

Three hundred patients with COVID-19 admitted to the Intensive Care Unit (ICU) of Shanxi Bethune Hospital from January 2020 to June 2021 were retrospectively collected. Based on body position and conscious state, all patients were divided into three groups: intubation prone position group ( $n=$ 110), awake prone position group ( $n=$ 90) and supine position group ( $n=$ 100); The acute physiology and chronic health evaluation II (APACHE-II) scores, blood gas indicators, complications and other relevant clinical indicators were compared among the three groups. One-way ANOVA was used to compare means between multiple groups for quantitative information that conformed to a normal distribution. Repeated measures ANOVA was used for repeated measures data. Component comparisons were made using the Kruskal-Wallis H rank sum test for non-normally distributed quantitative data.

RESULTS:

One-way repeated-measures ANOVA main effect analysis showed different effects of different treatments on PaO2 in patients with COVID-19 (F treatment $=$ 256.231, $P<$ 0.05), with the order of awake prone position group $>$ intubation prone position group $>$ supine position group. The effects of the three different treatments on P/F in patients with COVID-19 (F treatment $=$ 311.661, $P<$ 0.05), with the order of awake prone position group $>$ supine position group $>$ intubation prone position group; Moreover, the three treatments had different effects on APACHE II scores in patients with COVID-19 (F treatment $=$ 201.342, $P<$ 0.05), with the order of intubation prone position group $>$ supine position group $>$ awake prone position group.

CONCLUSION:

Intubation prone position and awake prone position can improve lung function to some extent in patients with COVID-19, and should be applied as early as possible in patients with COVID-19-induced ARDS.

Keywords

Prone position ventilation supine position coronavirus disease 2019 lung function efficacy

1. Introduction

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by novel coronavirus infection, with fever, dry cough and fatigue as its main manifestations. The virus, which broke out in China in December 2019 and spread rapidly the world, has posed a serious threat to the health of people worldwide [1, 2]. The pathogen of OVID-19 is severe acute respiratory syndrome coronavirus 2 (SARSCoV2), which specifically binds to the angiotensin converting enzyme 2 (ACE-2) receptor on the cell membrane and invades the cell [3]. However, ACE-2 receptors are highly expressed in many organs and cells of the body, including lung (alveolar epithelial cells, macrophages, etc.) [4], liver (hepatocytes) [5], heart (cardiomyocytes, smooth muscle cells) [6], kidney (tubular epithelial cells) [7] and gastrointestinal (epithelial cells) [8]. In other words, patients with COVID-19 often suffer from multiple organ dysfunction, such as acute respiratory failure (ARF), heart, kidney, liver dysfunction, and coagulation disorders [9], leading to severe hypoxemia and even respiratory and circulatory failure, which is life-threatening [10].

Patients with COVID-19 have been shown in numerous studies to die mainly due to disease-induced acute respiratory distress syndrome (ARDS) [11]. Constituting an important component of respiratory distress syndrome, ARDS is clinically characterized by intractable hypoxemia and progressive dyspnea after onset and is associated with varying degrees of intra- and extra-pulmonary disease as the disease progresses [12].

Most patients with ADRS due to COVID-19 require treatment in the intensive care unit and most require mechanical ventilation [13, 14]. At the beginning of the COVID-19 pandemic, treatment guidelines issued in many countries implied that mechanical ventilators must be used to treat patients with severe symptoms [15]. The Diagnostic and Treatment Plan for Novel Coronavirus Pneumonia (Trial Ninth Edition) issued by the National Health Commission of China (NHSC) clearly states that severe/critical patients with high risk factors for severe illness and rapid disease progression should be given standardized prone position ventilation (PPV), which recommends that the duration of prone positioning ventilation should be no less than 12 h per day [16]. PPV refers to the measures to help patients take a prone position during mechanical ventilation to improve their oxygenation status [17]. As an important lung protective ventilation strategy, PPV was proposed by Bryan [18] as early as 1974. This method increases the ventilation of dorsal lung tissue through position changes, promotes secretion clearance, and improves the stress distribution of lung tissue, thereby improving patient ventilation and reducing the incidence of ventilator-associated lung injury. It is indicated for patients with ventilation disorder, especially those with oxygenation disorder. Previous studies have shown that the mechanism is that when the patient is transferred from the supine position to the prone position, the gas is transferred from the anterior lung to the posterior lung. At the same time, the damaged interstitial lung is also filled with oxygenated blood. This physiological change effectively improves ventilation and blood flow [19]. When the PPV nursing strategy is applied for several hours, it can significantly reduce the mortality of patients with moderate to severe ARDS receiving mechanical ventilation [20], and when combined with lung recruitment, can improve oxygenation and prognosis in patients with severe ARDS without increasing the incidence of serious complications [21].

With the modernization of medical devices for mechanical ventilation, the parameters of the medical devices affect the prognosis and quality of survival of patients [22]. If professionals can use the right ventilation strategy to assist in the treatment of patients, it will bring more clinical benefits to the patients. Therefore, it is necessary to explore which ventilation strategy is more effective for the treatment of new coronary patients and can reduce complications.

Currently, most patients with severe pneumonia (SP) and ARDS in newly crowned pneumonia are treated with PPV, which has also been shown to be safe and effective by many studies [23]. However, most of these studies focused on the prone position treatment of patients with intubation, while prone position therapy in awake patients was less reported [24]. Therefore, this study was conducted to analyze the improvement of lung function in the prone position of patients, so as to provide clinical evidence for the formulation of PPV treatment protocols in awake patients.

2. Subjects and methods

2.1 Study subjects

Three hundred patients with COVID-19 admitted to the Intensive Care Unit (ICU) of Shanxi Bethune Hospital from January 2020 to June 2021 were collected retrospectively, and were divided into three groups: intubation prone position group ( $n=$ 110), awake prone position group ( $n=$ 90) and supine position group ( $n=$ 100) according to their body position and conscious state. Inclusion criteria: (1) Patients diagnosed with COVID-19 according to the guidelines [12]; (2) Patients admitted to the ICU; (3) The age of patients $\geqslant$ 18 years; (4) Patients with contraindications excluded; (5) Patients who voluntarily signed the written informed consent form within 48 hours of inclusion in the trial or whose family members signed the written informed consent form instead. Exclusion criteria: (1) Patients with the unstable state after spinal injury or fracture; (2) Patients with severe skin lesions who were not suitable for prone position; (3) Patients with a suspected cerebral hernia; (4) Patients with severe hemodynamic instability; (5) Patients who the operator thinks cannot be ventilated in a prone position; (6) Patients with acute hemorrhagic diseases; (7) Patients with cervical or spinal injuries or suspected injuries; (8) Pregnant women or patients with increased intracranial pressure and glaucoma. This study was approved by the Ethics Committee of our Hospital. All subjects in the study gave informed consent and signed a written consent form.

2.2 Study methods

Patients in the supine position group were cared for according to the routine nursing plan of the undergraduate course, and the group was in charge of 2–3 staff members who turned the patients once every 2 h to ensure that the bed unit was clean and wrinkle-free, and the pipelines were unobstructed and free of folds.

Before the prone position, patients were evaluated, including hemodynamics, sedation status, gastrointestinal tract condition, and whether the catheter was in place, unobstructed, and properly secured.

Figure 1.

Patient care procedures in the intubated prone group.

Figure 2.

Patient care procedures in the awake prone position group.

As shown in Fig. 1, patients in the intubation prone position group were cared in the following order: (1) A perineal nursing pad with water absorption face down was placed; (2) The distance of the artificial airway was measured, and the distance of the head turning pillow after being compressed was greater than that of the artificial airway; (3) Sheets were covered on the turning pillow; (4) The sheets were tightly rolled towards the patient and the turning pillow was fixed; (5) The head operator fixed the tracheal intubation and directed it; (6) the patient was moved and turned over, stopping briefly at 90^∘; (7) The hip operator changed hands up and down; (8) The shoulder operator changed hands up and down, and turned over conveniently; (9) The patient’s head and face were gently lifted to ensure that the artificial airway was not under pressure; (10) The old sheet was removed and the height of the turning pillow was reconfirmed to be appropriate; (11) The patient’s hands were placed on either side of the head while protecting the shoulders; (12) The catheter leads were arranged.

As shown in Fig. 2, patients in the awake prone position group were cared for according to the following steps: (1) The patients patient was moved to one side of the sickbed and aligned horizontally; (2) The patient faced 90^∘ to the opposite side; (3) The anterior chest electrode was removed and properly attached to the posterior back; (4) The pillow was placed on the head, chest, pelvis, lower limbs and instep in turn; (5) The hip operator changed hands up and down; (6) The shoulder operator changed hands up and down; (7) the patient was placed in the homeopathic prone position and the pillow position was arranged; (8) Arms were naturally upward; (9) Wires, pipelines and bed units were arranged.

2.3 Data collection

Basic information of patients, including: age, gender, clinical manifestations (fever, cough, headache, chest tightness, fatigue and disturbance of consciousness), past history (hypertension, diabetes, coronary heart disease, respiratory diseases, liver dysfunction, renal insufficiency, nervous system diseases and vaccination history), height, weight and body mass index (BMI).

Patients’ first vital signs after entering ICU, including body temperature, heart rate, respiration, systolic blood pressure, diastolic blood pressure and oxygen saturation. Laboratory examination (lymphocyte count, albumin level) and imaging findings of patients. Blood gas analysis of patients: arterial blood gas results of patients at different time points (prone position 0, 3, 6, 10 and 15 d), including pH, PaO₂, PaCO₂, oxygenation index (P/F) and lactic acid (Lac).

Prognostic evaluation of patients: The scores of acute physiology and chronic health evaluation II (APACHEII) were collected at different time points (prone position 0, 3, 6, 10 and 15 d). Patients were scored according to the APACHE-II scale for physiology, age, and previous health status, and missing items in the original data were calculated as 0 points. The lower the score, the better the prognosis. Complications occur during ICU hospitalization, and complications mainly include: (1) Pressure ulcers: a limited injury to the skin or subcutaneous tissues due to pressure, compound shear, or friction, including stages 1–4. (2) Skin injury: It is a symptom of skin abnormalities such as erythema, blisters, and vesicles that lasts for 30 min or even longer after removal of the tape and other products. (3) Catheter dislodgement: The catheter of the trachea is dislodged due to poor fixation or improper restraint of the patient. (4) Displacement of tracheal tube. (5) Reflux aspiration: If the patient’s oral secretion or gastroesophageal reflux enters the airway below the vocal folds during intubation, a large amount of gastric content gushes out from the mouth and nose, shortness of breath is obvious, and there is an increase in lung rales; the oxygen saturation level suddenly decreases, and the heart rate accelerates, or the gastric content is suctioned out from the patient’s airway, the patient will be judged as suffering from reflux aspiration.

2.4 Statistical analysis

All data from this study were statistically analyzed using SPSS 23.0 software, and normally distributed data were expressed as $x\pm s$ . One-way ANOVA was used for the comparison of means between multiple groups, the LSD test was used for two-way comparison between multiple groups, and repeated-measures ANOVA was used for repeated-measures data. Non-normally distributed data were expressed as M (Q1, Q3), and the Kruskal-Wallis $H$ rank sum test was used for comparison between groups. Moreover, counting data were expressed as examples or percentages, and $\chi^{2}$ test was used for comparison between groups, with $P<$ 0.05 indicating a statistically significant difference.

3. Results

3.1 General information

The comparison results of the baseline data of the three groups showed that there was no statistically significant difference in the proportion of sex composition, age of vaccination in COVID-19, body mass index, median number of days in prone position, duration of prone position per day (h) height and past history of clinical symptoms ( $P>$ 0.05). Overall, the patients in the three groups were well comparable, as shown in Table 1.

Table 1
Comparison of baseline data for the three groups

Item	Intubation-prone position group ( $n=$ 110)	Awake-prone position group ( $n=$ 90)	Supine position group ( $n=$ 100)	$F/\chi^{2}/Z$ value	$P$ value
Age (years old, $x\pm s$ )	54.25 $\pm$ 2.43	55.36 $\pm$ 2.54	55.42 $\pm$ 2.23	0.184	0.832
Male/female (cases)	58/52	39/51	44/56	2.296	0.317
Height (cm, $x\pm s$ )	163.5 $\pm$ 5.31	165.4 $\pm$ 4.50	166.7 $\pm$ 5.10	1.665	0.203
Body mass index (kg/m², $x\pm s$ )	19.52 $\pm$ 7.63	20.32 $\pm$ 8.75	21.5 $\pm$ 2.60	1.537	0.227
Clinical symptoms (cases)
Fever	72	56	57	1.601	0.449
Cough	75	70	62	5.567	0.062
Headache	69	60	64	0.432	0.843
Chest distress	41	43	49	3.537	0.171
Fatigue	41	45	55	3.368	0.186
Past medical history (cases)
Hypertension	50	43	42	1.365	0.505
Diabetes	46	40	51	0.911	0.634
Coronary heart disease	51	45	52	0.076	0.963
Respiratory diseases	60	43	55	2.870	0.238
Hepatic insufficiency	12	7	9	1.043	0.594
Renal insufficiency	16	9	7	4.268	0.118
Not vaccinated with COVID-19	14	11	9	1.239	0.538
vaccine (cases)
Median number of days in prone position	5.00 [4.00, 6.00]	6.00 [4.00, 7.00]	–	1.451	0.531
Duration of prone position per day	13.00 [12.00, 14.00]	13.89 [13.00, 15.00]	–	1.891	0.432

3.2 Comparison of vital signs, laboratory indicators and imaging results among the three groups

Table 2
Comparison of first vital signs, laboratory indicators and imaging results after admission to ICU

Item	Intubation-prone position group ( $n=$ 110)	Awake-prone position group ( $n=$ 90)	Supine position group ( $n=$ 100)	$F/\chi^{2}/Z$ value	$P$ value
Vital signs
Body temperature [ ${{}^{\circ}}$ C, M (Q1, Q3)]	37.31 (36.82, 37.52)	37.21 (36.52, 37.53)	37.20 (36.83, 37.62)	0.306	0.823
Heart rate [beats/min, M (Q1, Q3)]	92.00 (88.00, 103.00)	89.00 (83.00, 99.00)	87.00 (82.00, 91.00)	8.114	0.017
Respiratory rate [beats/min, M (Q1, Q3)]	20.00 (19.00, 22.00)	19.00 (17.00, 20.00)	17.00 (16.00, 20.00)	6.706	0.061
Oxygen saturation [%, M (Q1, Q3)]	91.00 (90.00, 93.00)	94.00 (91.00, 95.00)	94.00 (90.00, 96.00)	12.357	$<$ 0.001
Systolic blood pressure [mmhg, $x\pm s$ ]	123.25 $\pm$ 9.57	124.42 $\pm$ 9.99	123.43 $\pm$ 8.72	1.221	0.513
Diastolic pressure [mmhg, $x\pm s$ ]	73.45 $\pm$ 7.53	72.41 $\pm$ 8.31	74.40 $\pm$ 7.91	1.332	0.501
Laboratory indicators ( $x\pm s$ )
Lymphocyte count (10⁹/L)	0.61 $\pm$ 0.12	0.73 $\pm$ 0.23	0.71 $\pm$ 0.19	1.489	0.478
Albumin (g/L)	33.01 $\pm$ 2.12	35.11 $\pm$ 3.13	33.47 $\pm$ 2.99	1.843	0.410
Lung imaging infiltration (cases)	58	50	61	0.220	0.896

ICU, Intensive Care Unit.

See Table 2 for the first vital signs, laboratory and imaging results within 24 h after admission to the ICU. The results showed that there were no statistically significant differences in body temperature, respiratory rate, systolic blood pressure and diastolic blood pressure among the three groups (all $P>$ 0.05). There was a statistically significant difference in heart rate among the three groups ( $P<$ 0.05), and further comparison showed that intubation prone position group $>$ awake prone position group $>$ supine position group. Moreover, there was a statistically significant difference in oxygen saturation among the three groups ( $P<$ 0.05), and patients in the awake prone and supine groups had higher oxygen saturations than those in the intubated prone group, indicating good comparability of patients’ conditions when admitted to the ICU.

Table 3

Comparison of blood gas and APACHEII scores among the three groups at 0, 3, 6, 10 and 15 d after treatment ( $x\pm s$ )

Item		Intubation-prone position group ( $n=$ 110)		Awake-prone position group ( $n=$ 90)		Supine position group ( $n=$ 100)		$F_{\textit{interaction}}$ / $P_{\textit{interaction}}$ value	F time/ $P_{\textit{time}}$ value	$F_{\textit{treatment}}$ / $P_{\textit{treatment}}$ value
pH	0 d	7.41	$\pm$ 0.23	7.56	$\pm$ 0.19	7.42	$\pm$ 0.21	1.634/0.219	1.723/0.201	1.734/0.201
	3 d	7.42	$\pm$ 0.15	7.35	$\pm$ 0.21	7.45	$\pm$ 0.19
	6 d	7.43	$\pm$ 0.21	7.44	$\pm$ 0.33	7.46	$\pm$ 0.20
	10 d	7.42	$\pm$ 0.19	7.43	$\pm$ 0.23	7.52	$\pm$ 0.17
	15 d	7.42	$\pm$ 0.21	7.42	$\pm$ 0.18	7.46	$\pm$ 0.19
PaO₂ (mmHg)	0 d	56.91	$\pm$ 8.63	57.81	$\pm$ 7.69	57.77	$\pm$ 7.96	2.231/0.180	211.251/0.001	256.321/0.001
	3 d	69.93	$\pm$ 10.61	72.89	$\pm$ 9.69	65.76	$\pm$ 8.45
	6 d	84.13	$\pm$ 10.26	88.10	$\pm$ 8.26	80.10	$\pm$ 9.47
	10 d	117.94	$\pm$ 10.37	120.76	$\pm$ 9.42	113.79	$\pm$ 8.89
	15 d	121.94	$\pm$ 9.37	124.56	$\pm$ 11.37	117.33	$\pm$ 10.25
PaCO₂ (mmHg)	0 d	38.42	$\pm$ 3.66	37.35	$\pm$ 3.45	36.21	$\pm$ 3.66	1.652/0.203	0.723/0.762	0.734/0.701
	3 d	37.62	$\pm$ 5.43	38.79	$\pm$ 5.23	38.23	$\pm$ 4.43
	6 d	38.52	$\pm$ 3.06	37.35	$\pm$ 3.13	38.33	$\pm$ 3.23
	10 d	40.52	$\pm$ 3.45	39.52	$\pm$ 3.34	40.35	$\pm$ 3.75
	15 d	37.89	$\pm$ 6.87	38.45	$\pm$ 5.78	37.67	$\pm$ 4.87
P/F (mmHg)	0 d	113.53	$\pm$ 13.78	110.23	$\pm$ 10.98	110.76	$\pm$ 10.23	0.862/0.563	289.451/0.001	311.661/0.001
	3 d	123.63	$\pm$ 8.98	167,34	$\pm$ 11.39	143.53	$\pm$ 12.03
	6 d	149.83	$\pm$ 10.76	220.34	$\pm$ 12.59	210.53	$\pm$ 12.03
	10 d	167.34	$\pm$ 10.34	247.32	$\pm$ 12.51	220.34	$\pm$ 11.23
	15 d	198.45	$\pm$ 9.56	250.23	$\pm$ 10.56	230.45	$\pm$ 9.34
Lac (mmol/L)	0 d	1.91	$\pm$ 0.32	1.87	$\pm$ 0.31	1.86	$\pm$ 0.32	1.443/0.369	0.451/0.911	2.123/0.104
	3 d	2.02	$\pm$ 0.11	2.12	$\pm$ 0.24	2.34	$\pm$ 0.11
	6 d	1.80	$\pm$ 0.23	1.93	$\pm$ 0.24	1.80	$\pm$ 0.45
	10 d	2.31	$\pm$ 0.43	2.02	$\pm$ 0.32	2.24	$\pm$ 0.27
	15 d	2.22	$\pm$ 0.58	2.13	$\pm$ 0.29	2.01	$\pm$ 0.44
APACHEII scores	0 d	23.31	$\pm$ 2.32	19.45	$\pm$ 2.32	18.89	$\pm$ 2.76	0.721/0.736	102.781/0.001	201.342/0.001
	3 d	20.52	$\pm$ 1.83	17.63	$\pm$ 1.89	17.45	$\pm$ 1.99
	6 d	17.65	$\pm$ 2.01	14.35	$\pm$ 1.76	15.34	$\pm$ 2.01
	10 d	14.42	$\pm$ 1.96	10.34	$\pm$ 1.87	11.67	$\pm$ 2.10
	15 d	11.12	$\pm$ 1.82	7.62	$\pm$ 1.98	10.23	$\pm$ 1.03

APACHEII, acute physiology and chronic health evaluation II; PaO2, partial pressure of oxygen; PaCO2, partial pressure of carbon dioxide in artery; P/F, oxygenation index; Lac, lactic acid.

3.3 Comparison of blood gas analysis and APACHE-II score among the three groups

The effect of PPV therapy for 15 d on blood gas and APACHE scores of patients with COVID-19 was judged by single-factor repeated measurement analysis of variance. Shapiro-Wilk test showed that the data of each group were approximately normal distribution ( $P>$ 0.05). According to the test of the Mauchly spherical hypothesis, the variance-covariance matrix of each group was equal ( $P>$ 0.05), and the data were expressed as $x\pm s$ . The results were summarized as follows: There were no statistically significant differences in pH, PaCO₂ and Lac among the three groups. Specifically, no interaction effects were observed between PaO₂ treatment factors and time factors in the three groups ( $F_{\textit{interaction }}=$ 2.231, $P>$ 0.05), so the main effect was directly analyzed; Different treatment methods had different effects on PaO₂ in patients with COVID-19 ( $F_{\textit{treatment}}=$ 256.231, $P<$ 0.05), with the order of awake prone position group $>$ intubation prone position group $>$ supine position group after further comparison of PaO₂ magnitude in each group at 15 d. No interaction effects were observed between P/F treatment factors and time factors in the three groups ( $F_{\textit{interaction}}=$ 0.862, $P>$ 0.05), so the main effect was directly analyzed; Different treatment methods had different effects on P/F in patients with COVID-19 ( $F_{\textit{treatment}}=$ 311.661, $P<$ 0.05), with the order of awake prone position group $>$ supine position group $>$ intubation prone position group after further comparison of P/F magnitude in each group at 15 d. Moreover, no interaction effects were observed between the APACHE II scores and time factors in the three groups ( $F_{\textit{interaction}}=$ 0.721, $P>$ 0.05), so the main effect was directly analyzed; Different treatment methods had different effects on the APACHE II scores in patients with COVID-19 ( $F_{\textit{treatment}}=$ 201.342, $P<$ 0.05), with the order of intubation prone position group $>$ supine position group $>$ awake prone position group after further comparison of APACHE II scores in each group at 15 d, as shown in Table 3.

3.4 Comparison of complications among the three groups

The comparison of complications among the three groups showed that the supine position group had a higher incidence of pressure ulcers, but a lower incidence of skin injury, tracheal intubation displacement and regurgitating aspiration compared with the other two groups (all $P<$ 0.05). There was no statistical difference in the incidence of complications between the awake-prone position group and the intubation-prone position group ( $P>$ 0.05). Besides, no statistically significant differences were observed in catheter dislodgement rate among the three groups ( $P>$ 0.05), indicating that PPV performed during wakefulness did not reduce complications, as shown in Table 4.

Table 4
Incidence of complications related to prone position among the three groups (cases)

Complications	Intubation prone position group ( $n=$ 110)	Awake prone position group ( $n=$ 90)	Supine position group ( $n=$ 100)	$\chi^{2}$ value	$P$ value
Pressure ulcer	48	24	79	55.011	$<$ 0.001
Skin injury	72	41	17	61.182	$<$ 0.001
Catheter dislodgement	23	18	33	5.628	0.060
Tracheal intubation displacement	65	41	8	70.226	$<$ 0.001
Regurgitating aspiration	57	25	9	54.286	$<$ 0.001

4. Discussion

This study shows that awake PPV can improve PaO2, reduce FiO2, increase P/F, and prevent the aggravation of hypoxemi, which is consistent with the results of other studies [25]. Previous studies have shown that early mechanical ventilation and prone position therapy have many benefits for patients with moderate to severe ARDS caused by COVID-19, such as reducing ventilation support conditions and reducing their harmful effects on heart and other organs [26]. Currently, for hypoxemia caused by ARDS, the commonly used interventions in the clinic include PPV, high-frequency shock ventilation, neuromuscular block, and even extracorporeal membrane oxygenation (ECMO), of which PPV is the most preferred because of its simplicity and operability [27]. To cure patients with ARDS, the key is to improve hypoxemia to promote blood oxygenation, a crucial measure to improve oxygenation, which works in the following ways: (1) Achieve lung recruitment, which increases lung volume and improves atrophic alveolar entrapment [28]; (2) Promote gas exchange, which increases functional residual capacity and buffers changes in PaO₂ and PaCO₂ as well as injuries related to lung hyperinflation [29]; (3) Relieve gravity-dependent tolerance to achieve a lower differential pressure gradient in the thoracic cavity than in the supine position (SP), which optimizes intrapulmonary gas distribution, shrinks lung recruitment while limiting lung hyperinflation [30]; (4) Reduce intrapulmonary shunt, which relieves the pressure of the heart on the lung (especially the lower lobe of the left lung), improves the movement mode and position of diaphragm, and promotes lung recruitment [31]; (5) Achieve gradient pressure drop in the chest and change of body position, which is more conducive to secretion drainage [25]. Guérin et al. [32] showed that early and long-term prone position for ARDS patients can not only improve the blood gas of patients, but also reduce the mortality of patients. This view has also been confirmed in some META analyses [33, 34]. Therefore, PPV is strongly recommended in the treatment of ARDS. The COVID-19 pandemic has led to a sharp increase in the number of patients with acute respiratory distress syndrome who need respiratory support, resulting in ICU overload. Therefore, clinicians must use innovative methods to limit the need for mechanical ventilation, including awake prone position [35]. Some studies have investigated whether the use of awake prone position is related to the improvement of clinical outcomes, but there is limited scientific evidence on the prognostic value and clinical outcomes of initial awake prone position.

Meanwhile, the APACHEII scores of the three groups at various time points also showed that the APACHE II scores in the awake PPV group also gradually decreased and were lower as the treatment progressed compared to the intubation PPV group, demonstrating the feasibility of awake PPV for improving pulmonary function in patients with COVID-19 [25]. In awake patients, PPV therapy can, on the one hand, improve the ventilation/blood flow ratio to promote pulmonary recovery, increase lung compliance and reduce intrapulmonary shunts, and on the other hand, allow patients to retain spontaneous breathing to express discomfort with a relatively lower risk of complications and accidents [36]. Previous studies have shown that PPV is suitable for the following situations: (1) moderate and severe ARDS caused by various reasons, with an oxygenation index of 100–300 mmHg [37]; (2) 30%–60% of FiO₂ or 2–10 L/min of oxygen by mask or nasal cannula with SpO2 $>$ 94% using transnasal high-flow or non-invasive ventilator [38]; (3) Infiltration shadow in bilateral gravity-dependent areas in imaging [39]; (4) Patients who are conscious, can call for help, and can actively turn or cooperate with turning; (5) Patients who can tolerate position change.

Awake PPV promotes lung recruitment, improves oxygenation, relieves symptoms, while simultaneous postural drainage promotes secretion drainage and significantly improves pulmonary function in patients with COVID-19. In the literature, no serious adverse events were found in the study of conscious proneness. Nevertheless, the risks of pressure ulcers, intubation displacement, catheter dislodgement, skin injury, and regurgitating aspiration are still unavoidable. In addition, some trials reported tolerance problems in the awake prone position, as well as anxiety and musculoskeletal discomfort in patients [40, 41]. Therefore, the clinical utilization of the advantages of PPV needs to be accompanied by enhanced safety verification and standardized management [42]. In the treatment of patients with COVID-19, emphasis is placed on sensory control management in the treatment of patients with COVID-19 due to their specificity, so as to reduce the spread of the virus through droplets and aerosols, and to lower the risk of exposure of medical personnel through standard prophylaxis [43].

Certain limitations are still visible in this study. Firstly, it is a single-center study that does not guarantee consistency at baseline when the cohort is compared, and patients are likely to have other comorbidities that affect prognosis, resulting in an obscured association between treatment factors and outcome indicators in patients with COVID-19. Secondly, the treatment of patients is not standardized and unified, and different treatment methods may bring errors to the results. In addition, a smaller sample size is included in this study, resulting in poor test efficacy, and further sample size should be increased in follow-up. Finally, retrospective studies are neither likely to distinguish the temporal sequence of risk factors and outcomes, nor is it difficult to determine whether the risk factors identified in the paper occurred before or after infection due to the nature of the methods, resulting in less reliable results. For this reason, further multicenter, large-sample prospective studies are needed in follow-up.

5. Conclusion

PPV is an acute salvage measure for awake patients with COVID-19 severe disease complicated by acute respiratory distress syndrome, which has the ability to improve lung function and increase the success rate of treatment, and lays a solid foundation for further clinical dissemination of PPV standardization, but the risk of complications is unavoidable.

Ethics statement

The study was conducted in accordance with the Declaration of Helsinki and approved by the ethics committee of Shanxi Bethune Hospital. Written informed consent was obtained from all participants.

Availability of data and materials

All data generated or analysed during this study are included in this article. Further enquiries can be directed to the corresponding author.

Funding

This study was supported by Shanxi Province ‘136 Revitalization Medical Project Construction Funds’. The funding bodies played no role in the design of the study or in the collection, analysis, or interpretation of the data.

Author contributions

HF conceived the study; BY, YY and LJ participated in the design and data analysis and statistics; and HF helped draft the manuscript. All authors read and approved the final manuscript.

Footnotes

Acknowledgments

None to report.

Conflict of interest

None of the authors have any personal, financial, commercial, or academic conflicts of interest to report.

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Application of prone position ventilation in ventilation strategies for patients with COVID-19

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSION:

Keywords

1. Introduction

2. Subjects and methods

2.1 Study subjects

2.2 Study methods

2.4 Statistical analysis

3. Results

3.1 General information

Table 1 Comparison of baseline data for the three groups

Table 2 Comparison of first vital signs, laboratory indicators and imaging results after admission to ICU

3.4 Comparison of complications among the three groups

Table 4 Incidence of complications related to prone position among the three groups (cases)

5. Conclusion

Ethics statement

Availability of data and materials

Funding

Author contributions

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Comparison of baseline data for the three groups

Table 2
Comparison of first vital signs, laboratory indicators and imaging results after admission to ICU

Table 4
Incidence of complications related to prone position among the three groups (cases)