Role of Inhaled Nitric Oxide in Vascular Mechanics and Right Ventricular Function Following Cardiac Surgery
Phase: NA
Conditions: Collapsed Lung, Hemodynamic Stability
Sponsor: Fernando Suarez Sipmann

RONIN- CCV                                                                                  EudraCT Nº 2022-003884-37  
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Role of Inhaled Nitric Oxide in vascular 
mechanics and right ventricular 
function following cardiac surgery. 
EudraCT Nº 2022-003884-37        

RONIN- CCV                                                                                  EudraCT Nº 2022-003884-37  
Versión 2: September 1, 2023 
  
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1. INTRODUCTION 
Perioperative pulmonary hypertension (PH) and right ventricular dysfunction (RVD) during 
cardiac surgery are serious complications associated with delayed weaning from 
cardiopulmonary bypass (CPB) and significant postoperative morbidity and mortality (1). Their 
pathophysiology is multifactorial and includes factors such as left ventricular systolic or diastolic 
dysfunction, the systemic inflammatory response associated with CPB, reduced pulmonary 
endothelial NO production during CPB, and pulmonary factors like pulmonary ischemia-
reperfusion injury, surfactant dysfunction, increased susceptibility to pulmonary collapse, 
impaired pulmonary mechanics, and gas exchange impairment (2, 3). Inhaled nitric oxide (iNO) is 
a selective pulmonary vasodilator that has been successfully used to treat postoperative PH and 
RVD. Specifically, by reducing pulmonary arterial tone and resistance, iNO improves right 
ventricular (RV) performance despite its mild negative inotropic effect. Furthermore, iNO has 
been shown to effectively reduce pulmonary vascular resistance (4, 5), mitigate CPB-related 
inflammation (6), and more recently, reduce acute kidney injury and provide protection against 
chronic kidney diseases (7). Although clear benefits in outcomes have not been established, due 
to the aforementioned reasons, experts consider the use of iNO useful for perioperative 
treatment of increased pulmonary vascular resistance during cardiac surgery (8). 
Recently, we have studied the effects of lung collapse on RV function during CPB weaning and 
have described that a ventilation strategy aimed at minimizing collapse and maintaining 
homogeneously ventilated lungs, known as open lung approach (OLA), improves RV 
performance (9). Lung collapse is present in the majority of patients after cardiac surgery, often 
affecting more than 10% of the total lung tissue mass (10). Lungs remain collapsed during CPB, 
receiving only minimal blood flow through bronchial arteries, without protection against 
ischemia. Furthermore, the inflammatory response triggered by CPB circulation inactivates 
surfactant. This, along with atelectasis induced during anesthesia induction, results in a lung 
highly prone to collapse in the immediate perioperative period. Lung collapse has several 
negative consequences for both pulmonary function and pulmonary circulation. On one hand, it 
reduces functional lung size, affecting pulmonary mechanics, increasing transpulmonary 
pressure, and impacting gas exchange, reducing ventilation efficiency and increasing the 
demand for inspired oxygen. On the other hand, lung collapse reduces the cross-sectional area 
of the pulmonary vasculature, and unventilated or under-ventilated alveoli trigger and enhance 
hypoxic pulmonary vasoconstriction response, which is further amplified in the presence of 
concurrent respiratory or metabolic acidosis. All these factors lead to increased pulmonary 
vascular resistance, early PH, and RVD. Right ventricular dysfunction is related to difficulties in 
weaning from CPB, an increased demand for catecholamines and inotropic support extending 
into the postoperative period, where it can complicate early recovery by prolonging dependence 
on drugs and mechanical ventilation, ultimately affecting the individual patient's outcome. 
 

RONIN- CCV                                                                                  EudraCT Nº 2022-003884-37  
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The increase in pulmonary vascular resistance and PH after cardiac surgery and their response to 
different therapeutic strategies like iNO have been well documented. However, there is limited 
information on how such measures affect RV function and their true influence on perioperative 
evolution. In this study, we aim to evaluate modifiable pathophysiological treatments for 
postoperative PH and RVD. 
One pharmacological, iNO, and one non-pharmacological, the OLA strategy that combines lung 
recruitment and stabilization with individually optimized positive end-expiratory pressure 
(PEEP), and the possible synergistic effects of both interventions on RV performance. Apart from 
specifically targeting the described pathophysiological mechanisms, the combination of an OLA 
strategy and iNO could be especially beneficial, as modifying the pulmonary state through OLA 
could theoretically enhance the effects of iNO by significantly increasing the gas exchange area 
and, thus, alveolar ventilation. We will also study a series of closely related physiological 
variables to better characterize the effects of both strategies and their combination. This can 
help establish a better indication for iNO in cardiac surgery patients and improve our 
understanding of mechanisms that are also present in patients with acute respiratory distress 
syndrome (ARDS), albeit on a different scale. 
2. Hypothesis 
Inhaled nitric oxide (iNO) administered at a dose of 20 to 40 ppm in the immediate 
postoperative period of cardiac surgery improves pulmonary vascular mechanics and right 
ventricular function and synergistically interacts with alveolar recruitment in patients presenting 
with postoperative atelectasis. 
 
 
 
 
 
 
 
 
 
 

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3. Aims 
Primary aim 
• To study the effects of inhaled iNO on pulmonary vascular mechanics, right ventricular 
function, and right ventricular-vascular coupling in patients in the immediate 
postoperative period of cardiac surgery. 
Secondary aim 
• To compare the effects of iNO with standard care and with a lung recruitment maneuver 
on pulmonary vascular mechanics, right ventricular function, and right ventricular-
vascular coupling in patients in the immediate postoperative period of cardiac surgery. 
• To study patterns of redistribution of pulmonary blood flow measured by Electrical 
Impedance Tomography (EIT) that predict a positive effect on vascular mechanics and 
right ventricular function 
4. Patients 
Inclusion Criteria 
Patients undergoing cardiac surgery who meet the following criteria will be included in the 
study: 
• Age > 18 years 
• Under controlled mechanical ventilation in passive conditions 
• Presence of postoperative lung collapse (confirmed by pulmonary echocardiography and 
Air test) 
• Preoperative left ventricular ejection fraction (LVEF) ≥ 30%. 
• Absence of hypovolemia: absence of "kissing" ventricles and/or collapsibility index of the 
superior vena cava < 20%. 
• Stable spontaneous heart rhythm 
• Postoperative hemodynamic stability: 
• Mean arterial pressure (MAP) ≥ 60 mmHg 
• Central venous pressure (CVP) ≥ 10 mmHg 

RONIN- CCV                                                                                  EudraCT Nº 2022-003884-37  
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• Heart rate (HR) ≤ 100 bpm without tachyarrhythmias 
• Lactic acid ≤ 3 mmol/L 
• Single vasopressor treatment 
• Norepinephrine dose ≤ 0.2 μg/kg/min, without an increase ≥ 15% in the last 30 minutes. 
• Obtained informed consent 
Exclusion Criteria 
• Cor pulmonale or preoperative pulmonary vascular pathology 
• Absence of pre-existing chronic respiratory pathology. 
• Pre-induction arterial oxygen saturation (SpO2) < 97% by pulse oximetry 
• Chronic pulmonary hypertension (mPAP > 35 mmHg) related to advanced COPD r chronic 
thromboembolic disease. 
• Tricuspid or pulmonary valve surgery. 
• Intra or postoperative use of nitroprusside or nitroglycerin. 
• Preoperative dependency on inotropic or vasoconstrictor drugs. 
• Use of levosimendan. Patients receiving dobutamine may be included as long as the 
infusion is ≤ 2 μg/kg/min. 
• Contraindication for transesophageal echocardiography (See Appendix I) (11) 
• Absence of lung collapse 
• Pacemaker dependency  
 
 
 
 
 
 
 
 
 

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5. Methods 
5.1 Study Design 
This is a prospective controlled and randomized physiological study that will be conducted at 
two hospitals. The intervention period will be limited to the first 2-3 postoperative hours. With a 
total of 54 patients, the study recruitment period is expected to last for 18 months. 
Study Registration: EudraCT number 2022-003884-37 
5.2 Follow-up and Study Variables 
The main study variables will be right ventricular function parameters measured through 
transesophageal echocardiography (TEE), specifically those directly related to the estimation of 
right ventricular-vascular coupling (as described below). Additionally, variables derived from 
Electrical Impedance Tomography (EIT) will be recorded: regional distribution of ventilation and 
perfusion, and EIT pulsatility (12) (see below). Additional variables related to pulmonary vascular 
mechanics will be included in patients monitored with a pulmonary artery catheter. 
 5.2.1 Conventional Monitoring 
Patients will receive routine postoperative monitoring, including invasive blood pressure 
measurement, surface electrocardiogram, SpO2, and central venous pressure (CVP). 
Mechanical ventilation will be provided by a Servo-U ventilator (Getinge, Solna, Sweden). This 
ventilator allows for the recording of all respiratory parameters, pulmonary mechanics, and 
ventilatory waveforms (Pressure, flow, and volume - time). 
5.2.2 Echocardiography 
At specified time points in the protocol, a specialist will perform transesophageal 
echocardiography (TEE) to assess right ventricular function and pulmonary circulation following 
the latest recommendations from the American and European Societies of Echocardiography 
(13). The following echocardiographic parameters will be studied: 
 
 
 

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Parameters of Right Ventricular Function 
• Right ventricular end-diastolic and left ventricular end-diastolic diameters ratio 
•  Eccentricity index 
• Right ventricular fractional shortening 
• Tricuspid annular plane systolic excursion (TAPSE) 
• S wave (Systolic Tissue Velocity) 
• Myocardial Performance Index (MPI) 
• Right ventricular ejection efficiency (RVEe) (14) 
• TAPSE normalized to afterload (TAPSE/PAPs) 
• Global longitudinal strain (speckle tracking) 
Parameters of Afterload 
• Estimated systolic pulmonary arterial pressure (PAPs) 
• Estimated pulmonary vascular resistance using Doppler 
• Notching pattern in the right ventricular outflow tract 
• Right ventricular outflow tract acceleration time (RVOT-AT) 
• Pulmonary pulse transit time (pPTT) (15) 
From these right ventricular function variables, we have selected the primary variables (used for 
sample size estimation) that best inform about right ventricular-vascular coupling (16): RVEe; 
TAPSE/PAPs; pPTT, and contractility indicators: S' and TAPSE. 
 
 
 
 

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5.2.3 Electrical Impedance Tomography (EIT) 
Patients will be monitored with Electrical Impedance Tomography (EIT) using the TMT impel 
Medical system (Sao Paulo, Brazil) (12): 
Specifically for this study, the Enlight 18000 system will be used to monitor: 
Regional distribution of lung ventilation and perfusion: Relative distribution of ventilation and 
perfusion in predefined regions of interest. The chest plane will be divided into ventral and 
dorsal regions, and additionally into four quadrants: Upper right and left lungs, and lower right 
and left lungs. The relative distribution (percentage) of ventilation (tidal volume) and perfusion 
(cardiac output) will be measured and compared in each selected region. 
Changes in lung aeration (ΔEELZ delta end-expiratory lung volume): Direct measurement of 
static lung volume related to lung collapse and the effects of positive end-expiratory pressure 
(PEEP). 
Pulmonary arterial pulsatility: After filtering the respiratory component using a high-pass filter, 
changes in impedance caused by pulmonary arterial pulsatility will be analyzed in each region of 
interest. 
Distribution of pulmonary blood flow: Three perfusion studies by EIT will be conducted at each 
measurement point. To obtain the distribution of pulmonary perfusion, a small volume of 10 ml 
of 10% saline solution will be injected into the distal lumen of a central venous catheter in the 
jugular or subclavian position during a brief 20-second apnea. To induce apnea, ventilator 
settings will be changed to CPAP while maintaining the same PEEP level. The injected saline 
solution will be analyzed based on the first-pass kinetics, and the perfusion distribution result 
will be immediately displayed on the monitor. During EIT acquisition, the external temporary 
pacemaker will be turned off. 
5.2.4 Pulmonary Artery Catheter 
 
For patients monitored with a pulmonary artery catheter during the intraoperative period, the 
following parameters will be recorded: pulmonary artery pressure (PAP), SvO2, cardiac output 
(CO), right ventricular systolic work index (RVSWI), pulmonary vascular resistance index (PVRi), 
pulmonary pulsatility (PAp), effective pulmonary arterial elastance (effPAE), transpulmonary 
pressure gradient (TPG), and right ventricular pressure (RVP). Since a relatively low number of 
patients are expected to be monitored with a pulmonary artery catheter, these derived 
variables will have only descriptive value. 
 

RONIN- CCV                                                                                  EudraCT Nº 2022-003884-37  
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5.3 
Specific Study Interventions 
 
5.3.1 Inhaled Nitric Oxide (iNO) 
 
The iNO administration device will be the So KinoxTM (Air Liquide). This device is one of the best 
and safest clinical devices for administering inhaled nitric oxide, routinely used in the intensive 
care unit. It ensures accurate dosing of iNO regardless of inspiratory flow and volume. It 
continuously and accurately monitors the concentration of nitric oxide in inspired gas and the 
fractions of inspired oxygen and nitrogen dioxide, a toxic byproduct of nitric oxide. The product 
technical information is available in the supplementary documentation. iNO will be initiated at a 
dose of 20 ppm immediately after randomization in the corresponding groups. After 30 minutes, 
a first assessment will be performed, and the iNO dose can be increased to 40 ppm as long as 
there is no increase in methemoglobin levels above 2.5% and in case there is no improvement in 
ventricular function or ventricular-vascular coupling, defined by the presence of any of the 
following: 
§ TAPSE ≤ 16 mm 
§ TAPSE/PAPs ≤ 0.26 
§ S' ≤ 9 cm·sec^-1 
§ RVOT-AT ≤ 100 ms 
 
5.3.2 Recruitment Maneuver (RM) and PEEP Individualization 
 
In the group assigned to pulmonary recruitment, the maneuver will be performed as follows: 
 
Change the ventilation mode to pressure-controlled ventilation. 
Respiratory rate of 15 cmH2O, FiO2 0.4, Inspiratory pressure of 15 cmH2O, Increase PEEP from 5 
to 20 cmH2O every 5 breaths (20 seconds each step at a respiratory rate of 15). The last step 
increases inspiratory pressure from 15 to 20 cmH2O, maintained for 10 breaths (40 seconds). 
Immediately after completing the maneuver, the ventilation mode will return to volume-
controlled ventilation, and a rapid decremental PEEP titration will be performed. PEEP will be 
reduced stepwise from 16 cmH2O in 2 cmH2O steps (30 seconds at each step) while keeping 
baseline ventilator settings. The closing pressure will be identified based on maximum 
compliance (17) and/or EIT (18). After a new short recruitment maneuver, ventilation will 
continue with baseline settings but with PEEP set to the detected closing pressure level. 
 
 
 
 
 
 

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Safety criteria: The RM will only be performed if stability conditions described in the inclusion 
criteria are met. The maneuver will be interrupted if any of the following situations occur during 
the maneuver: 
- Desaturation: SpO2 ≤ 89% 
- Mean arterial pressure < 55 mmHg or a decrease ≥ 30% from baseline 
- Arrhythmias (tachyarrhythmias >120 bpm or bradyarrhythmias < 50 bpm) 
- If the patient requires a pacemaker, heart rate of 70-90 bpm based on hemodynamic response. 
 
5.3.3 Transesophageal Echocardiography (TEE) 
 
An expert cardiologist will perform TEE at three time points during the investigation in all 
patients following standard procedures. A Philips CX50 portable device will be used. 
 
5.5 Study Protocol 
 
5.5.1 Patient Admission 
 
Routine and specific study monitoring will be initiated. According to the clinical protocol, 
baseline ventilation will consist of volume-controlled ventilation with VT 6-8 ml/kg; PEEP 5 
cmH2O; RR 15 bpm; I:E 1:2; FiO2 1. The first routine blood gas measurement will be obtained 
with these parameters. Subsequently, FiO2 will be reduced to 0.4. 
 
5.5.2 Diagnosis of Atelectasis 
 
The presence of atelectasis will be determined using lung ultrasound: 
 
Lung Ultrasound: 
Lung ultrasound will be used to confirm atelectasis. Ecographic collapse (consolidation pattern) 
must be present for the patient to be included in the study. Lung ultrasound will be performed 
at the posterior axillary line in the subdiaphragmatic region. Echographic collapse will be 
defined as the presence of a consolidation pattern and absence of "lung sliding" or B-lines at the 
posterior axillary line in the subdiaphragmatic region (19). Alternatively, atelectasis can be 
confirmed during transesophageal echocardiography (TEE): Presence of a consolidation pattern 
with dynamic air bronchogram associated with B-lines in the left lower lobe during medial-lower 
esophageal position of the probe (20). If no ultrasound-visible collapse is present, the patient 
will not be randomized and will be labeled as a screened patient. Additionally, an air test will be 
performed to confirm the functional impact of collapse through the air test. 
 
 
 

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5.7 Study Groups 
 
After confirming atelectasis using the air test and lung ultrasound, patients will be  
randomly assigned using block randomization to one of the following three groups: 
 
1) Standard treatment (CONT): Patients will be managed according to routine clinical protocol, 
standardizing interventions in both participating centers. 
 
2) iNO 20-40 ppm (iNO): iNO at 20 ppm will be initiated immediately after randomization and 
data collection. The dose will be re-evaluated after the first 30 minutes and may be increased to 
a maximum of 40 ppm depending on the observed response in ventricular function. 
 
3) iNO 20-40 ppm + Pulmonary Recruitment (iNO-RM) 
 
  
 
 
 
Figure 1: Study protocol 

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5.7.1 Admission Evaluation 
Upon admission, patient monitoring and stability will be checked. After routine arterial and 
venous blood gas extraction, the air test and lung ultrasound will be performed to determine the 
presence of atelectasis. If the presence of collapse is confirmed, informed consent will be 
obtained from the family if it has not been given previously. If affirmative, randomization will be 
conducted, and impedance belts will be placed. 
5.7.2 Protocol Measurement Time Points: 
T1: Admission 
Baseline measurements will be taken upon arrival in the intensive care unit, once the patient has 
been monitored, postoperative atelectasis has been confirmed (using lung ultrasound or air test), 
and the patient is in a stable condition after initial laboratory tests. 
T2: Baseline 
30 minutes after the first measurement under reference ventilation conditions. Depending on 
the observed response in right ventricular function, the iNO dose will be adjusted. If no 
improvement is observed, the iNO dose will be increased to 40 ppm. 
T3: Final 
30 minutes after applying the specific protocol for each group. 
5.8 Statistical Analysis 
Patients will be assigned to intervention groups through block randomization to ensure equitable 
distribution among the three intervention groups. 
5.8.1 Sample Size 
At the participating hospital (Hospital Universitario de la Princesa), cardiac surgery provides a 
continuous daily flow of patients (one or two per day) who could potentially become candidates 
for the study if they meet inclusion criteria and not exclusion criteria. Assuming a 15% 
improvement in right ventricular function measured by echocardiographic parameters in 
response to iNO or pulmonary recruitment (9) and a confidence level of 95%, the estimated 
sample size will be 54 patients, 18 in each group (27 per center). However, due to the lack of 

RONIN- CCV                                                                                  EudraCT Nº 2022-003884-37  
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sufficient studies analyzing right ventricular response to iNO, RM, or both, the final sample size 
may be adjusted based on preliminary results from initial pilot patients and study progress. 
5.8.2 Statistical Methods 
Variables will undergo descriptive analysis of central tendency measures including mean, median, 
dispersion, standard deviation, and interquartile range, respectively. Homoscedasticity and 
normality assumptions will be confirmed using Levene's and Shapiro-Wilk tests, respectively. 
Variables with normal distribution and similar variance will be compared using the t-test, and 
variables with non-normal distribution using the non-parametric Wilcoxon test. Pearson's chi-
squared test will be used for categorical variables to compare groups at the three measurement 
points in the study, and Fisher's exact test when expected frequencies are < 5. 
For the comparison of more than two means with homoscedastic variances and normal 
distribution, ANOVA with post hoc testing will be conducted. For variables with heteroscedastic 
variances and/or non-normal distribution, the Kruskal-Wallis post hoc test will be applied. To 
analyze temporal evolution, a repeated measures ANOVA will be used with the intervention type 
as the main factor. In case of non-normality, the non-parametric Friedman test will be applied. 
Statistical significance will be set at p ≤ 0.05. Statistical analysis will be performed using Stata 
v.15. 
6. Safety and Adverse Events 
To ensure safety during the 2-hour duration of the research protocol, the following precautions 
will be taken: 
The inclusion of unstable patients or those who have had significant intraoperative 
complications leading to instability will be avoided. 
6.1 Use of Inhaled Nitric Oxide (iNO) 
1. The use of high and prolonged doses of iNO can be associated with adverse effects such as 
the formation of methemoglobin and NO2. Methemoglobin levels above 8-10% can lead to 
symptoms related to functional anemia, as methemoglobin cannot bind oxygen. NO2 is a 
common air pollutant that can be toxic at elevated levels due to the formation of reactive 
oxidative stress species. 
Given the doses used and the duration of use, it is unlikely that elevated levels of both will 
occur. However, methemoglobin levels will be monitored through two blood gas 
measurements, one at 30 minutes and another at the end of iNO administration (1 hour). The 
SoKinox system continuously monitors NO2 levels in the inspired gas and has safety alarms. 

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iNO may precipitate or worsen left heart failure in patients with preexisting ventricular 
dysfunction due to increased left preload. This protocol specifically excludes patients with poor 
preexisting ventricular function or instability. Cardiac function will be monitored through 
echocardiography performed at 30 minutes (T2) and immediately after (T3) iNO administration. 
If there are clear signs of deteriorating left ventricular function (more than 20% drop in LVEF) 
during the examination compared to the initial function measured upon admission (T1), 
administration will be stopped. 
The following criteria (any of them) will be established for dose reduction or discontinuation of 
iNO: 
o NO2 levels > 1 ppm 
o Methemoglobin fraction > 2.5% 
o Variations in inspired oxygen concentration ± 5% compared to ventilator settings 
o Development of left ventricular failure data (drop in LVEF > 20% compared to 
initial level (T3) in echocardiographic controls. 
 
6.2 Pulmonary Recruitment Maneuver 
The recruitment maneuver can cause transient hemodynamic deterioration and, less frequently, 
barotrauma. Safety criteria have been established to interrupt the maneuver (see 5.3.2): 
o Desaturation: SpO2 ≤ 89% 
o Mean arterial pressure < 55 mmHg or decrease ≥ 30% from baseline 
o Arrhythmias (tachyarrhythmias >120 bpm or bradyarrhythmias < 50 bpm) 
o If the patient requires a pacemaker, a heart rate of 70-90 bpm based on 
hemodynamic response. 
Barotrauma is a much less frequent and highly unlikely complication in patients with healthy 
lungs (as included in this study) and with the proposed pressures and duration (very brief and at 
moderate pressures) in this study. 
A section for recording adverse effects will be added to the Case Report Form (CRF) of the study 
(in Excel format). 
 

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7. Ethical Considerations 
The intervention period is very short, and most procedures are applied routinely in the 
postoperative period. Special precautions will be taken to interfere as little as possible with 
normal postoperative times and management (an average of 4 to 6 hours until patients are fully 
awake and extubated). However, since patients are randomized to receive different 
interventions, a study insurance will be organized. 
During the study period, patients will remain sedated, primarily due to the continuous effects of 
anesthesia and, secondly, because routine administration of short-acting hypnotics and opioids 
is given during these early postoperative hours to ensure gradual and incident-free awakening. 
In any circumstance of patient discomfort or inappropriate early awakening with agitation, pain, 
or fighting against the ventilator, additional sedation/analgesia will be provided as per standard 
clinical practice. This will ensure patient comfort and prevent additional stress. 
All research procedures will strictly adhere to the principles of good clinical practice and ethical 
principles established in the Declaration of Helsinki and the Oviedo Convention on Human 
Rights and Biomedicine. 
7.1 Direct Access to Data/Source Documents 
The information generated and obtained through the implementation of this study is considered 
confidential and should be treated as such at all times. Study subjects will be identified by a 
coded subject number. All data generated in the study will be subject to the General Data 
Protection Regulation (GDPR) and the Spanish Organic Law 3/2018 of December 5 on the 
Protection of Personal Data. 
Both the responsible trial investigators and a representative of the sponsor or health authorities 
will have access to the information recorded throughout the study. Patient identities will not be 
revealed in any publication of study results. 
7.2 Control and Quality Assurance 
During the study's development, the sponsor or its representatives will conduct periodic 
monitoring visits to ensure that the protocol and Good Clinical Practice (GCP) standards are 
followed. The investigator and the center will allow sponsor monitors or their representatives, 
as well as competent health authorities, direct access to the original documents for verification. 
The study center may undergo reviews by the Ethics Committee or quality assurance audits 
conducted by the sponsor or its affiliates, or inspections by competent health authorities. It is 

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important that investigators and relevant personnel are available during monitoring visits and 
possible audits or inspections and allocate sufficient time for the process. 
7.3 Ethics 
General and specific guidelines for investigators: 
Investigators will strictly adhere to the provisions of this protocol, fully completing Case Report 
Forms (CRFs), which will be submitted in a timely manner to the sponsor for data analysis. The 
trial will be conducted in accordance with the recommendations for clinical trials and drug 
evaluation in humans outlined in the Declaration of Helsinki (revised in various locations) and 
the current Spanish Legislation on Clinical Trials. 
7.4 Informed Consent (IC) 
The IC document must comply with ICH GCP, local administrative regulations, and legal 
requirements. The IC document used in this study and any changes made to it during the study 
must be pre-approved by the Ethics Committee (CEIm) and the sponsor before its use. The 
investigator must ensure that all study patients, or their legal representatives, are fully informed 
about the nature and objectives of the study and the potential risks associated with 
participation. The investigator or their designee will obtain written informed consent from each 
patient or their legal representative before performing any specific study activity, and a copy 
will be provided to the patient or their legal representative for retention. The investigator will 
retain the original copies of all signed consent documents. 
For this study, informed consent will be obtained from each patient before the surgical 
intervention.z 
7.5 Data Handling and Record Archiving 
Documentation Archive: 
There will be a documentation archive for all data, which will be kept intact in both paper and 
electronic formats for 25 years following the completion of the study. This archive should 
contain the following elements: 
1. CEIm approval of the protocol and informed consent form. 
2. Copies of the signed informed consent form and approved protocol, with any 
amendments if applicable. 
3. Any correspondence related to the study with the sponsor during its course. 
4. Any correspondence with the CEIm. 

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5. Signed acceptance of the protocol. 
6. Curriculum vitae of the principal investigator and other members of the research team. 
7. Record of signatures of research team members. 
8. Delegation of tasks within the research team. 
9. Reporting of serious adverse events. 
10. Contract between the sponsor and the research team. 
11. Copies of data collection forms. 
Documentation will be archived following Good Clinical Practice guidelines. 
 
7.6 Case Report Form (CRF) / Data Recordin 
For the purposes of this protocol, a CRF refers to a paper form, an electronic data record, or 
both, depending on the data collection method used in this study. An electronic CRF in Excel 
format will be used for this study. A CRF must be completed for each patient included in the 
study. The data included in the CRF are the exclusive property of the Sponsor and must not be 
made available to third parties in any form, except for authorized representatives of the 
Sponsor or competent health authorities, without written authorization from the Sponsor 
The investigator will have the final responsibility for collecting and reporting all clinical, safety, 
and analytical data entered into the CRF and any other data collection documents (source 
documents), ensuring they are accurate, authentic/original, attributable, complete, consistent, 
legible, current, and enduring, and available when needed. The CRF will be signed by the 
investigator or an authorized team member to attest to the accuracy of the contained data. Any 
corrections made to CRF annotations or source documents must be dated, initialed, and 
explained (if necessary) and must not obscure the original annotation. 
 
7.7 Monitorin 
• Given that only 2 centers (Madrid and Barcelona) are participating in the study, it is 
planned to have 2 monitors located in each of the respective centers/cities. The monitor 
cannot, under any circumstances, be part of the investigative team. 
• The objectives of study monitoring will be to ensure that: 
• The rights and integrity of the subjects are protected. 
• Trial data is accurate, complete, and verifiable with source documents. 
• The trial is conducted in compliance with the approved protocol, following GCP and 
current regulations. 

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Monitoring Plan: 
• Given the characteristics of the study, a risk-focused monitoring approach will be 
implemented. The variables collected in the CRF will be reviewed with special emphasis 
on safety variables and adverse effects. Verification and validation of the collection of 
key variables will be performed. 
• Three monitoring visits will be scheduled (2 during the study and one final closing visit) 
during which the following checks/verifications will be conducted: 
• Critical variables to be monitored: 
• Verification of the collection of: 
I. 
Informed Consent Verification 
II. 
Confirmation of eligibility criteria 
III. 
Correct randomization and administration of study drug 
IV. 
Verification that identified data as critical variables. Review of source documents 
V. 
Review of safety assessments (AEs, SAEs) 
• Specific verifications to be performed at each visit: 
a) Written informed consent was obtained before each subject's participation in the trial. 
b) The investigator recruits only subjects who meet the selection criteria. 
c) The approved protocol is being followed correctly. 
d) The time and storage conditions of iNO are acceptable, and supplies are sufficient during 
the trial; it is only administered at the doses specified in the protocol. 
e) Source documents and other trial records are accurate, complete, up-to-date, and 
properly archived. 
f) Accuracy and integrity of data entered into the CRF with respect to source documents 
and other trial-related records. 
g) All adverse events have been reported appropriately and within the timelines specified 
in GCPs, the protocol, the Ethics Committee (CEIm), and relevant legal requirements. 
h) The investigator maintains essential documents (Investigator File). 

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i) Reporting any protocol deviations and taking necessary actions to prevent recurrence of 
detected deviations. 
• Conduct a final study closure visit to ensure essential documentation (Investigator File). 
 
7.8. Insurance 
 
Although the study could be considered of low intervention according to Article 2 of Royal Decree 
1090/2015, the sponsor will procure insurance since the use of iNO could be on the boundary of 
its indication. 
 
7.9 Publication Policy 
The results of this clinical trial may be published in specialty journals in the first quartile. 
 
8. Budget - Financial Report and Financing Plan 
 
This study has received a research grant from Air Liquide (France), which will sponsor it. The total 
amount received will be 75,000 euros, distributed equally between the two participating centers. 
This amount will cover the costs of IRB evaluation, insurance for this clinical trial, and specific 
disposables required: 
 
- Adhesive conductive tape covers and flow sensors for IET measurements. 
- Hypertonic saline solution used for perfusion studies. 
 
   Cost for each center will be:   
• 50 units of 10 ml 20% saline solution ------------------------------------- 50€. 
• 50 units of 10 ml 10% saline solution ------------------------------------- 50€. 
• 25 Adhesives (belt covers) ---------------------------------------------- 75 euros per unit ------- 1875 € 
• 25 Flow sensors ------------------------------------------------------ 86.282 euros per unit ------ 2157 € 
 
Total 4132 € 
 
Additionally, for the reference center, the following costs are included: 
• Evaluation by the Ethics Committee (CEIm) ------------------------------------ 1000 € 
• Medical insurance --------------------------------------------------------- approximate cost --- 6000 €. 
    
Total 7000 € 
 

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The therapeutic gas nitric oxide and the disposable products necessary for an iNO therapy session 
will be provided by Air Liquide at no cost to the participating centers. The product sheet is 
provided as additional documentation. 
 
 
9. References 
 
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II: Pathophysiology, Clinical Importance, and Management of Right Ventricular Failure. 
Circulation 2008; 117:1717–1731  
2. Denault A, Deschamps A, Tardif J-C, et al.: Pulmonary hypertension in cardiac surgery. Current 
Cardiology Reviews 2010; 6:1–14  
3. Denault AY, Tardif JC, Mazer CD, et al.: Difficult and Complex Separation from  
Cardiopulmonary Bypass in High-Risk Cardiac Surgical Patients: A Multicenter Study. Journal of 
Cardiothoracic and Vascular Anesthesia 2012; 26:608–616  
4. Morita K, Ihnken K, Buckberg GD, et al.: Pulmonary vasoconstriction due to impaired nitric 
oxide production after cardiopulmonary bypass. The Annals of Thoracic Surgery 1996; 
61:1775– 1780  
5. Solina AR, Ginsberg SH, Papp D, et al.: Dose response to nitric oxide in adult cardiac surgery 
patients. Journal of Clinical Anesthesia 2001; 13:281–286  
6. Gianetti J, Sarto PD, Bevilacqua S, et al.: Supplemental nitric oxide and its effect on myocardial 
injury and function in patients undergoing cardiac surgery with extracorporeal circulation. The 
Journal of Thoracic and Cardiovascular Surgery 2004; 127:44–50  
7. Lei C, Berra L, Rezoagli E, et al.: Nitric Oxide Decreases Acute Kidney Injury and Stage 3  
Chronic Kidney Disease after Cardiac Surgery. American Journal of Respiratory and Critical Care 
Medicine 2018; 198:1279–1287  
8. Germann P, Braschi A, Rocca GD, et al.: Inhaled nitric oxide therapy in adults: European expert 
recommendations. Intensive Care Medicine 2005; 31:1029–1041  
9. Longo S, Siri J, Acosta C, et al.: Lung recruitment improves right ventricular performance after 
cardiopulmonary bypass. Eur J Anaesth 2017; 34:66–74  
10. 
Tenling A, Hachenberg T, Tyden H, et al.: Atelectasis and gas exchange after cardiac 
surgery. Anesthesiology 1998; 89:371–378  
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Hilberath JN, Oakes DA, Shernan SK, et al.: Safety of Transesophageal Echocardiography. 
J Am Soc Echocardiog 2010; 23:1115–1127  

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12. 
Frerichs I, Amato MBP, Kaam AH van, et al.: Chest electrical impedance tomography 
examination, data analysis, terminology, clinical use and recommendations: consensus 
statement of the TRanslational EIT developmeNt stuDy group. 2017. p. 83–93.  
13. 
Rudski LG, Lai WW, Afilalo J, et al.: Guidelines for the Echocardiographic Assessment of 
the Right Heart in Adults: A Report from the American Society of Echocardiography:Endorsed 
by the European Association of Echocardiography, a registered branch of the European Society 
of Cardiology, and the Canadian Society of Echocardiography. Journal of the American Society 
of Echocardiography : official publication of the American Society of Echocardiography 2009; 
23:685–713  
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López-Candales A, Lopez FR, Trivedi S, et al.: Right ventricular ejection efficiency: a new 
echocardiographic measure of mechanical performance in chronic pulmonary hypertension. 
Echocardiography (Mount Kisco, NY) 2014; 31:516–523  
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Prins KW, Weir EK, Archer SL, et al.: Pulmonary Pulse Wave Transit Time is Associated with 
Right Ventricular–Pulmonary Artery Coupling in Pulmonary Arterial Hypertension. Pulm Circ 
2016; 6:576–585  
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Todaro MC, Carerj S, Zito C, et al.: Echocardiographic evaluation of right ventriculararterial 
coupling in pulmonary hypertension. Am J Cardiovasc Dis 2020; 10:272–283  
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Sipmann FS, hm SHB, Tusman G, et al.: Use of dynamic compliance for open lung positive 
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Costa ELV, Borges JB, Melo A, et al.: Bedside estimation of recruitable alveolar collapse 
and hyperdistension by electrical impedance tomography. Intensive Care Medicine 2009; 
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APPENDIX I 
 
Contraindications for the performance of a Transesophageal Echocardiogram: 
Esophageal Pathology: stenosis, trauma, tumor, scleroderma, Mallory-Weiss syndrome, 
diverticulum. Esophagitis, history of dysphagia, upcoming gastrointestinal surgery, active upper 
gastrointestinal bleeding, esophagectomy, symptomatic hiatal hernia, prior thoracic 
radiotherapy.