Cardiology

Utility of non-invasive synchronized intermittent mandatory ventilation in acute cardiogenic pulmonary edema

a b s t r a c t

Backgrounds: acute cardiogenic pulmonary edema (ACPE), one of the outcomes of Acute heart failure , is a common reason in a critical condition with respiratory distress. Non-invasive synchronized intermittent manda- tory ventilation(nSIMV) mode, which includes inspiratory pressure in addition to positive end expiratory pres- sure with/without pressure support provided in the non-invasive continuous positive airway pressure plus/ pressure support(nCPAP/PS) mode can be effective in hypercarbia and the associated changes in consciousness. This study aimed to demonstrate the efficacy of nSIMV in ACPE. Methods: Patients who presented with clinical acute respiratory failure and were admitted to the critical care unit of the emergency department with the diagnosis of ACPE were included. Patients were placed on non-invasive mechanical ventilators with an oronasal mask under the nCPAP/PS and nSIMV modes. Pulse and respiratory rate, systolic and diastolic blood pressure and Glasgow coma scores(GCS), HACOR(heart rate, acidosis, con- sciousness, oxygenation and respiratory rate) scores, pH, PaCO2, PaO2/FiO2 and lactate at the time of admission and at 30 and 60 min were evaluated.

Results: Twenty-two patients were recruited, nCPAP/PS mode was 10 and nSIMV mode was 12. Although there was no statistically significant difference between the two groups in terms of the change in the relevant param- eters from admission to 60 min, the decreases in PaCO2 and lactate levels (31.4% vs. 21.2%, p = 0.383; 68.8% vs. 47.1%, p = 0.224; respectively) and the increase in PaO2 and PaO2/FiO2 values (34% vs. 14.2%, p = 0.710 and 132.1% vs. 52.7%, p = 0.073; respectively) were higher in the nSIMV group.

Conclusion: The nSIMV mode is as effective as the nCPAP/PS mode in the treatment of patients with ACPE. We be- lieve that the nSIMV mode can be preferable, particularly in patients with hypercarbia who have relatively lower GCS and oxygenation.

Introduction

Acute cardiogenic pulmonary edema (ACPE), one of the outcomes of acute heart failure , is a common reason for patients visiting the emergency department (ED) in a critical condition with respiratory dis- tress. While patients with AHF respond well to Conventional treatment consisting of oxygen support, diuretics and vasodilators, mechanical ventilation might be needed in severe cases. In such patients, the use of non-invasive mechanical ventilation (NIMV) techniques that shorten the length of hospital and Intensive care unit stay, reduce the risk of

* Corresponding author at: Department of Emergency Medicine, Faculty of Medicine, Karabuk University, Karabuk 78100, Turkey.

E-mail address: [email protected] (B. Cekmen).

pneumonia and decrease the rate of complications associated with en- dotracheal intubation is recommended, instead of Invasive mechanical ventilation [1]. In addition, NIMV can also be preferred due to its efficacy, ease of application and reduced overall cost of hospitaliza- tion.

Various NIMV modes have been used in the treatment of ACPE in ad- dition to routine therapy. These consist of non-invasive continuous pos- itive airway pressure (nCPAP) with/without pressure support (PS) [2] and non-invasive positive pressure ventilation (NIPPV, also called bilevel or BiPAP) [3], proportional assist ventilation (PAV) [4] and adapted servo ventilation (ASV) [5] modes. Although all these modes have been shown to be effective in the treatment of ACPE, there is no consensus on the superiority of one mode over another.

Different types and brands of ventilators are utilized in intensive care, critical care and Emergency care settings (home, portable,

https://doi.org/10.1016/j.ajem.2022.03.044

transport, ICU type etc.). These differences lead to an increased diversity of ventilation modes in terms of both naming and features, while also posing a challenge to clinicians in complying with the guidelines for making choices. nCPAP and BiPAP modes, which are recommended for ACPE, are mostly used in home type or portable ventilators. Moreover, advanced ventilators offer the nCPAP/PS mode that involves the addition of pressure support (PS) to positive end expiratory pressure (PEEP) in- stead of the nCPAP mode alone. Similarly, the non-invasive synchro- nized intermittent mandatory ventilation (nSIMV) mode that includes frequency, PS and inspiratory pressure (Pi) in addition to PEEP is used in- stead of the BiPAP mode. The nSIMV mode has been shown to be bene- ficial, particularly in patients with obstructive pulmonary disease who have hypercarbia, due to the provision of volume with Pi in addition to frequency [6], and it is also believed to be effective in patients with ACPE due to the development of hypercarbia and the resulting clouded consciousness [7]. In this study, we aimed to demonstrate the efficacy of the nSIMV mode in the treatment of patients with ACPE.

Materials and methods
1. Study design and setting

This study was conducted with patients who presented to the emer- gency department of Prof. Cemil Tascioglu City Hospital, a tertiary Emer- gency Medicine Clinic in Istanbul, Turkey, between January 2019 and December 2019. The study was approved by the Clinical Trials Ethics Committee of the Faculty of Medicine, Ataturk University, Erzurum, Turkey (Approval Date/No:27 December 2018/116). This study was

Table 1

Distribution of patients’ demographic characteristics, clinical, vital and laboratory param- eters.

Parameters nCPAP/PS nSIMV p

Age	68 [49-81]	74,5 [63-85]	0,165??
Gender
Male, n(%)	4 (40)	6 (50)	0,691?
Female, n(%)	6 (60)	6 (50)
Pulse (beat/min)	106 [81-168]	103,5 [78-140]	0,608?
Respiratory rate (breath/min)	37 [27-46]	32 [26-38]	0,033?
GCS	14,5 [12-15]	13,5 [11-15]	0,433?
Systolic BP (mmHg)	200,5 [175-280]	198,5 [160-240]	0,327?
Diastolic BP (mmHg)	107,5 [87-150]	101 [85-140]	0,577?
pH	7,3 [7,1-7,4]	7,2 [7-7,3]	0,129?
SaO₂ (%)	83 [57,6-99,3]	83 [60-97]	0,809?
PaCO₂ (mmHg)	54,9 [31,2-81,8]	63 [38-81,6]	0,259?
PaO₂ (mmHg)	81,7 [35,6-323]	56,1 [44,4-187,2]	0,256?
Lactate (mmol/L)	3,8 [2,4-7]	4,8 [1,9-10,9]	0,304?
PaO₂/FiO₂	165,5 [111-300]	142,5 [88,8-233]	0,169?
HACOR Score	10,5 [4-16]	11,5 [6-15]	0,594?

Descriptive statistics for numerical variables are given as median [minimum - maximum] depending on the distribution; for categorical variables as number (%).

nCPAP/PS: non-invasive continuous positive airway pressure plus pressure support, nSIMV: non-invasive synchronized intermittent mandatory ventilation. GCS: Glasgow coma score, BP: blood pressure, SaO2: O2 saturation, PaCO2: partial CO2 pressure, PaO2: partial O2 pressure, FiO2: inspired O2 concentration.

* By Mann-Whitney U test.

?? By Pearson Chi-Square, Fisher’s Exact or Fisher Freeman Halton test.

designed as a non-inferiority trial and conducted with patients who pre- sented to the emergency department with respiratory distress due to ACPE.

Image of Fig. 1

Fig. 1. Flow chart.

Table 2

Changes in ventilator parameters and number of patients.

Parameters nCPAP/PS nSIMV

F (breath/min) - 18 [16-18]

Pi (cmH₂O) - 14,5 [8-18]

PEEP (cmH₂O) 7 [5-7] 7 [6-7]

FiO₂ (%) 60 [50-100] 70 [60-98]

PS (cmH₂O) 12 [8-14] 14 [8-18]

Number of patients during the treatment period

30 min, n 10 12

60 min, n 7 7

Variation, n(%) 3 (- %30) 5 (- %41,7)

Descriptive statistics for numerical variables are given as median [minimum - maximum] depending on the distribution; for categorical variables as number (%).

nCPAP/PS: non-invasive continuous positive airway pressure plus pressure support, nSIMV: non-invasive synchronized intermittent mandatory ventilation. F: respiratory fre- quency, Pi: inspiratory pressure, PEEP: positive end-expiratory pressure, FiO2: inspired O2 concentration, PS: pressure support.

1. Patients
  1. Inclusion criteria

Patients over 18 years old who presented with clinical acute respira- tory failure and were admitted to the critical care unit of the emergency department with the diagnosis of ACPE were included. ACPE diagnosis was made by an emergency medicine specialist and proven by moderate-severe shortness of breath, a respiratory rate > 25 breaths/ per minute, paradoxical breathing that involved the use of accessory muscles of respiration, tachycardia, hypertension, bilateral crackles and gallop rhythm on auscultation. Signs of congestion were observed on the chest X-ray. The NIMV mode to be employed was immediately assessed in patients who had pH < 7.35 and PaO2 < 60 mmHg or SaO2 < 94% on room air at the time of admission. The patients who were placed on nCPAP/PS or nSIMV modes, among the NIMV modes se- lected for treatment, were included.

- 1. Exclusion criteria

Patients with cardiac and respiratory arrest, a baseline pH < 7.10, fa- cial deformity or face mask incompatibility, a Glasgow coma score < 8, those who were unresponsive or who had a severely reduced level of consciousness, patients who were highly agitated or uncooperative, those who had an unstable cardiac rhythm and patients with ST eleva- tion or bigger than 2 mm diffuse ST-segment depression with signs of acute myocardial infarction as seen on the ECG performed at admission,

were excluded from the study. In addition, patients who were diag- nosed with pneumonia, acute exacerbation of chronic obstructive pul- monary disease, asthma, myocardial infarction or acute respiratory distress syndrome after investigations and treatment were also ex- cluded. Those with comorbidities such as chronic obstructive pulmo- nary disease or neuromuscular disease were excluded due to the possibility of hypercarbia in baseline blood gases, which could lead to misinterpretation of the efficacy of the selected NIMV mode. Modes (such as PAV, ASV etc.) and methods (HFNC and conventional treat- ment) other than the nCPAP or nSIMV were excluded.

1. Treatment protocol

Patients who met the criteria were placed on non-invasive mechan- ical ventilators (VELA Comprehensive, CareFusion Corporation) with an oronasal mask under the nCPAP/PS and nSIMV modes. Nitroglycerine and furosemide treatment were administered to all included patients as needed. The patients were re-evaluated every 30 min and the treat- ment protocol was terminated in those who exhibited clinical improve- ment at the end of the first hour.

In the nCPAP/PS mode, PEEP was set to 5-8 cm H2O, PS to 8-20 cm

H2O and FiO2 to 60-100%. In this mode, PS was increased or decreased by 2-4 units to provide a tidal volume of 6-8 mL/kg. In order to ensure an SaO2 value higher than 90%, FiO2 was increased or decreased by mul- tiples of 10 starting from 100% depending on the Pulse oximeter and blood gas values. PEEP value was increased or decreased by increments of one, in order to ensure a partial pressure of O2 (PaO2) of 80-250 mmHg in arterial blood gas analysis.

In the nSIMV mode, PEEP was set to 5-8 cm H2O, PS to 8-20 cm H2O, FiO2 to 60-100%, Pi to 8-20 cm H2O, and frequency to 12-20 breaths/ min. Pi and frequency values were increased and decreased according to the partial pressure of CO2 (PaCO2) in blood. PS and Pi values were increased and decreased by multiples of 2-4 to ensure a tidal volume of 6-8 mL/kg. The changes in PEEP and FiO2 were adjusted according to the criteria for the nCPAP/PS mode.

1. Measurement

Pulse and respiratory rate, systolic and diastolic blood pressure and Glasgow Coma Scores (GCS) were recorded at the time of admission and these measurements were repeated every 30 min. Arterial blood gas analysis was conducted at admission and pH, PaCO2, PaO2/ FiO2 and lactate values were recorded. The measurements were repeated at 30 and 60 min. With the data collected, HACOR (heart rate, acidosis,

Table 3

Clinical and laboratory findings of the patients at the time of admission, 30th and 60th minutes.

Parameters	Admission	30th minute	60th minute	p?
	nCPAP/PS (n:10) nSIMV (n:12)	nCPAP/PS (n:10) nSIMV (n:12)	nCPAP/PS (n:7) nSIMV (n:7)	nCPAP/PS	nSIMV
Pulse rate(beat/min)	106 [81-168] 103,5 [78-140]	92 [77-112] 88,5 [65-120]	88 [75-101] 76 [61-116]	0,004	0,012
Respiratory rate(breath/min)	37 [27-46] 32 [26-38]	27,5 [15-38] 24 [18-30]	25 [14-34] 20 [16-30]	0,001	0,002
GCS	14,5 [12-15] 13,5 [11-15]	15 [12-15] 15 [14-15]	15 [12-15] 15 [15-15]	0,050	0,003
Systolic BP (mmHg)	200,5 [175-280] 198,5 [160-240]	138,5 [120-172] 143 [130-193]	148 [98-159] 144 [125-151]	0,002	0,005
Diastolic BP (mmHg)	107,5 [87-150] 101 [85-140]	73,5 [60-90] 85 [57-111]	72 [61-95] 76 [61-100]	0,005	0,004
SaO₂ (%)	83 [57,6-99,3] 83 [60-97]	97,8 [88-100] 99 [96-100]	96,9 [84-99,2] 96,5 [91-99,1]	0,002	0,003
PaCO₂ (mmHg)	54,9 [31,2-81,8] 63 [38-81,6]	44,5 [31,5-100,4] 44,1 [28-60,9]	41 [31-90,4] 49,4 [25,5-54,6]	0,018	0,002
PaO₂ (mmHg)	81,7 [35,6-323] 56,1 [44,4-187,2]	143,6 [82,4-472] 165,9 [87,4-352]	93,6 [50-220] 120,5 [59-198,3]	0,050	0,012
Lactate (mmol/L)	3,8 [2,4-7] 4,8 [1,9-10,9]	2,6 [0,8-3,9] 2,3 [1,2-7,1]	2,1 [0,8-3,7] 2,3 [0,9-6,1]	0,002	0,002
PaO₂/FiO₂	165,5 [111-300] 142,5 [88,8-233]	258,5 [149-476] 242 [151-350]	260 [156-373] 283 [233-400]	0,002	0,002
Hacor Score	10,5 [4-16] 11,5 [6-15]	2 [0-9] 3 [0-5]	0 [0-8] 2 [0-3]	0,001	0,001
pH	7,3 [7,1-7,4] 7,2 [7-7,3]	7,3 [7,2-7,4] 7,3 [7,2-7,5]	7,4 [7,3-7,5] 7,3 [7,3-7,5]	0,004	0,001

Descriptive statistics are given as median [minimum - maximum].

* By Friedman test.

Table 4

Proportional (%) comparison of changes in clinical and laboratory findings depending on the treatment.

Parameters	30th minute			60th minute
	nCPAP/PS (n = 10)	nSIMV (n = 12)	p?	nCPAP/PS (n = 7)	nSIMV (n = 7)	p?
Pulse (beat/min)	-13,6 [-42,9 - -2,5]	-15,8 [-30,3-11]	0,489	-21,1 [-41,1 - -4,9]	-19,2 [-35-7,7]	0,999
Respiratory rate (breath/min)	-31,1 [-55,9-0]	-25 [-42,1 - -10,7]	0,552	-37,1 [-58,8 - -7,4]	-37,5 [-38,5 - -14,3]	0,797
GCS	0 [0-25]	11,3 [0-36,4]	0,209	0 [0-25]	15,4 [0-36,4]	0,233
Systolic BP (mmHg)	-31,3 [-41,8 - -14]	-26,1 [-45,8 - -10,7]	0,166	-38,3 [-45,6 - -20,5]	-22,5 [-39,6 - -10]	0,165
Diastolic BP (mmHg)	-34,8 [-44,2 - -15,2]	-15,1 [-40 to -7]	0,010	-32 [-43,6 - -13,8]	-28 [-35,8 - -9,1]	0,128
SaO₂ (%)	18,4 [-3,2-70,7]	18,1 [1,7-62,6]	0,974	14 [0,2-68,2]	8,3 [-0,5-62,5]	0,535
PaCO₂ (mmHg)	-13 [-41,8-22,7]	-22,2 [-52,4 - -5,4]	0,159	-21,2 [-43,1-10,5]	-31,4 [-46,1 - -10,6]	0,383
PaO₂ (mmHg)	85,1 [-64,5-482,7]	111,2 [-2,9-545,9]	0,381	14,2 [-31,9-146,3]	34 [-14-340,7]	0,710
Lactate (mmol/L)	-38 [-78,6 - -3,2]	-45 [-61,1 - -17,7]	0,974	-47,1 [-75 to -16]	-68,8 [-75 to -35,3]	0,224
PaO₂/FiO₂	32,3 [1,7-252,6]	71 [24-188,9]	0,346	52,7 [22-176,3]	132,1 [55,3-266,7]	0,073
Hacor Score	-82,6 [-100-33,3]	-73,9 [-100 to -55,6]	0,526	-100 [-100 to -33,3]	-84,6 [-100 to -72,7]	0,360
pH	1,1 [-0,7-2,8]	1,5 [0,6-3,3]	0,306	1,4 [0-3,1]	2,3 [1,4-4,4]	0,159

Descriptive statistics are given as median [minimum - maximum].

* By Mann-Whitney U test.

consciousness, oxygenation and respiratory rate) scores were calculated at the baseline and once every thirty minutes. Mechanical ventilatory support was ended after 30 or 60 min at the discretion of the clinician based on the improvement of symptoms and the clinical picture, con- ventional treatment was continued and the study was terminated.

1. Outcomes

At the primary endpoint, the increase in PaO2/FiO2 and pH, and the decrease in PCO2, lactate and HACOR score were compared in order to evaluate the efficacy of the each mode at the end of treatment. At the secondary endpoint, the reduction in heart rate, respiratory rate, sys- tolic and diastolic blood pressure, increase in the GCS and SaO2 level were observed.

1. Statistical analysis

In order to summarize the data obtained in the present study, descriptive statistics were provided in a table consisting of median, minimum and maximum values depending on the distribution of con- tinuous (numeric) variables. Categorical variables were summarized with numbers and percentages. Normality of numeric variables was tested with the Shapiro-Wilk, Kolmogorov-Smirnov and Anderson- Darling tests. In the comparison of two independent groups, Mann Whitney U test was used when numeric variables did not exhibit a nor- mal distribution. In the comparison of the differences between categor- ical variables according to groups, Pearson Chi-squared test was used for 2 x 2 tables for expected counts of 5 and above. Fisher’s Exact Test was used for expected counts below 5 and Fisher’s Freeman Halton test for RxC tables for expected counts below 5. Friedman test was used to eval- uate the changes between measurements taken at three different timepoints. Durbin-Conover test was used to determine the differences between measurements. Statistical analyses were conducted with the “Jamovi project (2020), Jamovi (Version 1.6.13.0) [Computer Software] (Retrieved from https://www.jamovi.org)) and JASP (Version 0.14.1.0) (Retrieved from https://jasp-stats.org)” software, and the level of signif- icance (p-value) was set at 0.05.

Results

Of the 98 patients who presented to the emergency department with acute respiratory failure, 22 were included in the study according to the inclusion and exclusion criteria; as specified in the flowchart. (Fig. 1) nCPAP/PS mode was used in 10 and nSIMV mode in 12 patients. Patient demographics as well as clinical, vital and laboratory parameters are shown in Table 1. There was no statistically significant difference

between the two groups in terms of the clinical features and arterial blood gas measurements except the respiratory rate at the time when patients first presented and before treatment. Although respiratory rates were higher in the nCPAP/PS group, both groups exhibited high re- spiratory rates, which supported the diagnosis (37 vs. 32 breaths/min). PaCO2 values, lactate levels and HACOR scores were higher in the nSIMV group (63 vs. 54.9 mmHg, 4.8 vs. 3.8 mmol/L, 11.5 vs. 10.5, re- spectively; p > 0.05). Moreover, GCS, pH, PaO2 and PaO2/FiO2 values were lower in the nSIMV group, although the difference was not statis- tically significant (13.5 vs. 14.5, 7.2 vs. 7.3, 56.1 vs. 81.7 mmHg, 142.5 vs. 165.5 mmHg, respectively; p > 0.05).

Three patients (30%) in the nCPAP/PS group and five patients (41.7%) in the nSIMV group were taken off ventilator support at 30 min since there was no need for further treatment, whereas treat- ment was continued for up to one hour in the remaining patients. The changes in the number of patients and Ventilation parameters used in both groups during the treatment period are summarized in Table 2.

Clinical and laboratory findings at the time of admission and at 30 and 60 min were recorded (Table 3). Both groups exhibited a statisti- cally significant change in all parameters (for all values p < 0.05).

The changes in data collected in the primary and secondary out- comes were calculated in percentages. The decrease in heart rate, respi- ratory rate, systolic and diastolic blood pressure, PaCO2, lactate levels and HACOR scores and the increase in the SaO2 level, GCS and PaO2/ FiO2 were determined. The 2 groups were compared in terms of the changes at 30 and 60 min. Comparing the changes in the two groups from admission to 30 min, it was found that the increase in PaO2 and PaO2/FiO2 values (111.2% vs. 85.1% and p = 0.381; 71% vs. 32.3%, p = 0.346, respectively) and the proportional decrease in PaCO2 (22.2% vs. 13%, p = 0.159) value were higher in the nSIMV group compared to the nCPAP/PS group, although not statistically significant, whereas the decrease in HACOR scores (73.9% vs. 82.6%, p = 0.526) was similar in the two groups. In addition, considering the changes in the two groups from admission to 60 min, the decrease in PaCO2 and lactate levels (31.4% vs. 21.2%, p = 0.383; 68.8% vs. 47.1%, p = 0.224, respectively) and the increase in PaO2 and PaO2/FiO2 values (34% vs. 14.2%, p = 0.710 and 132.1% vs. 52.7%, p = 0.073, respectively) at one hour post- treatment were higher in the nSIMV group (Table 4) (Fig. 2).

Discussion

Various non-invasive mechanical ventilation modes have been used in patients with ACPE and most of these methods were found to be ef- fective in previous studies. In a systematic review published in 2019, it was shown that the application of NIMV in addition to standard medical care is beneficial in the treatment of ACPE and has a positive effect on

Fig. 2. The changes in the two groups from admission to 60 min.

Image of Fig. 2

the outcome [8]. Belenguer-Muncharaz et al. were compared non- invasive mode and CPAP mode in ACPE treatment, and it was found that the non-invasive mode significantly increased the PaO2/Fio2 ratio after one hour, but there was no difference between other treatment- related parameters. In addition, the rate of intubation, duration of ven- tilation, ICU, and length of hospital stay were similar in both NIMV groups [9]. In a multicenter study conducted in Italy, in which 1293 pa- tients participated, standard oxygen therapy, CPAP, and Bi-PAP treat- ments were compared in patients with acute respiratory failure due to ACPE, and the non-invasive modes used in the study showed high clin- ical efficacy in treatment. Also, it emphasized that NIMV modes can be used as rescue treatments in patients who received only oxygen therapy [10]. Bilevel modes were more frequently used in studies related to re- spiratory failure as mentioned before, there are no studies regarding the use of nSIMV mode in patients with ACPE. The present study is the first study to evaluate the efficacy of nSIMV mode in patients with ACPE. nSIMV is a relatively new mode, and studies showed that this mode is effective in respiratory support in preterm infants with primary apnea and respiratory distress [11,12].

This mode, as evaluated in the present study, is believed to be effec- tive possibly due to its own peculiarities, considering the pathophysiol- ogy of ACPE. The data obtained in this study showed that the nSIMV mode is as effective as the nCPAP/PS mode in the treatment of patients with ACPE. We reached this conclusion due to the comparable changes in the clinical and laboratory parameters of the patients. While the de- crease in vital signs such as respiratory rate and systolic and diastolic blood pressure as well as the decrease in pH and HACOR scores were similar in the two groups, the decrease in PaCO2 and lactate levels and the increase in PaO2 and PaO2/FiO2 values were higher in the nSIMV group. Although both modes have been found to be effective in treat- ment, it was observed that there are some parameters that would influ- ence the preferred mode of any particular practitioner.

Although there was no statistically significant difference between patient data, nSIMV mode was particularly preferred in patients with higher PCO2 levels and HACOR scores and lower GCS, pH, PaO2 and PaO2/FiO2. Despite the differences in data, the fact that all patients showed similar clinical improvement supports this idea. Looking at the relevant literature, previous studies and reviews have recom- mended bilevel modes and especially modes that contain frequency support for patients with hypercarbia and high dyspnea scores, wherein the modes were shown to increase oxygenation further [3,13]. Although there is no clear meta-analysis or systematic review on this topic, the above recommendations support the decisions of the practitioners in this study.

1. Limitations

There are some limitations in our study. First of all, the sample size was small. Of the patients who presented with acute respiratory failure within the specified time interval, those diagnosed with pneumonia, acute exacerbation of chronic obstructive pulmonary disease, asthma, myocardial infarction or acute respiratory distress syndrome were ex- cluded, which resulted in a smaller sample size. Another limitation was that the length of hospital stay as well as short- and long-term mor- tality rates were not evaluated within the scope of this study. The effi- cacy of the modes employed was evaluated by measurements taken at 30 and 60 min, so that any differences outside this time-span may have been masked.

Conclusion

The nSIMV mode is as effective as the nCPAP/PS mode in the treat- ment of patients with ACPE. We believe that the nSIMV mode can be preferable, particularly in patients with hypercarbia who have relatively lower GCS and oxygenation.

Financial support

None.

CRediT authorship contribution statement

Bora Cekmen: Conceptualization, Methodology, Writing - original draft, Writing - review & editing. Busra Bildik: Writing - original draft, Data curation, Conceptualization. Oner Bozan: Writing - review & editing, Validation, Formal analysis. Seref Emre Atis: Data curation, Methodology, Writing - original draft. Serkan Dogan: Data curation, Supervision. Abdullah Osman Kocak: Writing - review & editing, Supervision, Methodology, Data curation.

Declaration of Competing Interest

None.

References

Keenan SP, Sinuff T, Cook DJ, et al. Does noninvasive positive pressure ventilation improve outcome in acute hypoxemic respiratory failure? A systematic review. Crit Care Med. 2004;32:2516-23.
Ferrari G, Milan A, Groff P, Pagnozzi F, Mazzone M, Molino P, et al. Continuous pos- itive airway pressure vs. pressure support ventilation in acute cardiogenic pulmo- nary edema: a randomized trial. J Emerg Med. 2010 Nov;39(5):676-84.
Masip J. noninvasive ventilation in acute heart failure. Curr Heart Fail Rep. 2019 Aug;

16(4):89-97.

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Utility of non-invasive synchronized intermittent mandatory ventilation in acute cardiogenic pulmonary edema

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Utility of non-invasive synchronized intermittent mandatory ventilation in acute cardiogenic pulmonary edema

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