Introduction: Prematurity refers to babies born before 37 weeks of gestation that through technological advances survival is increasing, since most of them are referred to the Neonatal Intensive Care Unit (NICU). Hemodynamic monitoring is of fundamental importance in the care provided to critically ill patients and mechanical ventilation (MV) is often used for the recovery and maintenance of newborns, especially premature infants with any pathology that causes cardiorespiratory failure. Considering this, it is necessary to look for ways to treat these newborns (NB), being the therapeutic positioning one of the simplest and most fundamental to reduce the consequences of the mechanical advantages of the respiratory system of newborns. Objective: To evaluate the hemodynamic repercussions in the various therapeutic positions in premature newborns under invasive mechanical ventilation. Method: A field study to be conducted will be randomized on an experimental, quantitative and descriptive character. It will be developed at the Santa Casa de Misericórdia do Pará Foundation (FSCMPa), in the Neonatal Intensive Care Unit. The population to be evaluated will be preterm infants with gestational age ≤37 weeks, on invasive mechanical ventilation, with no congenital malformations, with the diagnosis of intracranial hemorrhage and that those responsible, after being informed, authorized to participate in the research. Being excluded the preterm infants without legal companion, who are affected by any unfavorable clinical condition, which makes the change of unfeasible position, children with neuromuscular diseases, tracheostomized. A sample will be randomly selected in groups: Prono Group (GP), Supine Group (GS) and Lateral Decubitus Group (GDL). The decubitus to be adopted for each research subject will then be registered by the researcher in a specific form, recording as respiratory cardiological responses: respiratory rate (RR), heart rate (HR) and peripheral oxygen saturation (SPO2), temperature (T) and pressure blood pressure (BP). Such clinical responses will be noted prior to NB positioning, then positioned according to the group to which they will belong for 30 minutes, and then there will be another selection of vital signs.

The present field study to be carried out will be controlled clinical trial, randomized, experimental, quantitative and analytical. The research will be carried out in accordance with the ethical aspects recommended in the Declaration of Helsinki and Nuremberg Code, and by the research standards that may involve human beings of the National Health Council. Parents and guardians of premature newborns eligible for the survey will be invited to consent to the participation of newborns in the survey, in which the purpose, objectives and procedures of the research will be explained, requesting the signature of the Informed Consent Form and Informed and the Informed Consent Term.Then, access to data related to the newborn's medical record will be performed through the presentation of the Data Use Commitment Term. The sample will be randomly separated into groups: Prone Group, Supine Group and Lateral Decubitus Group. The decubitus to be adopted for each research subject will then be registered by the researcher in a specific form that will contain the following information: identification, gender, Apgar in the first and fifth minutes, GA, weight, use of surfactant and amount of doses, time of use of mechanical ventilation, length of hospital stay and others, with this information being obtained from the newborn's medical record, this step will provide data that will characterize the sample. For data acquisition via medical records, the researcher will submit the consent form for data use. The most used physiological parameters are vital signs, such as heart rate and percutaneous oxygen saturation, as they are the most easily observed responses. The most used physiological parameters are vital signs, such as heart rate and percutaneous oxygen saturation, as they are the most easily observed responses. This is due to the fact that babies who need intensive care are usually under these assessments constantly by pulse oximeters and because they have been the best scientifically validated among the physiological responses. The vital signs of heart rate (HR), often respiratory rate (RR) and blood pressure (BP), can be influenced by the infant 's age and health condition. Peripheral oxygen saturation may have its results altered by the baby's behavioral state and pulmonary conditions. The assessment of HR and RR, indirectly, may reflect respiratory discomfort, it is common to observe tachypnea and some patients present tachycardia for not accepting or tolerating the positioning they are submitted. To record the monitoring of cardiorespiratory physiological responses, an interval of 2 hours after the diet will be respected so that there are no complications during the procedure. The respiratory rate (RR) will be collected for this, the thoracic incursions of the patients will be observed for one minute, counted on a digital clock, and to measure the heart rate (HR) and peripheral oxygen saturation, a pulse oximeter will be used, provided by the institution , positioned on the newborn's foot. Axillary temperature will also be measured with a thermometer specific to each NB and blood pressure with a device from the institution.

Such clinical responses will be noted before the positioning of the NB, then participants will be positioned according to the group they belong to for 30 minutes, and then there will be a new verification of vital signs. During the time they are positioned, the RN will be asked not to receive routine procedures from the NICU or any stimulation by the health team. Only in cases that require urgent intervention. Being evaluated 1 times a day in the morning shift for two weeks. The collected data will be stored in Microsoft Excel® spreadsheets , which will serve to perform a simple descriptive statistics that will be presented in percentages, arranged in graphs and tables. Statistical analysis will be based on the use of statistical tests that best fit the study proposal through the Biostat ® statistical package . In order to know the profile of the data, the Shapiro-Wilk test will be applied to verify whether the data under analysis presented normality. To compare the mean values of the data, the ANOVA test will be performed, followed by the Newman-Keuls multiple comparison test for the variables: heart rate, respiratory rate, oxygen saturation and the Studen t test for the variables: blood pressure and axillary temperature. In all tests, the level for rejecting the null hypothesis will be set at 5% (p<0.05).

Inclusion Criteria:

• PTNB with GA ≤37 weeks
• In ventilation invasive mechanics
• With absence of congenital malformations
• With absence a diagnosis of intracranial hemorrhage
• That the guardians after being informed, authorized to participate in the research

Exclusion Criteria:

• PTNB without a legal companion
• Who are affected by some unfavorable clinical condition that makes it impossible to change position
• Children with neuromuscular diseases
• Tracheostomized