pneumonia is the second cause of hospital acquired infections after catheter site infection that leads to prolonged hospital stays , increased morbidities and higher expenses[1 , 2 ] .
ventilator associated pneumonia ( vap ) is the most common kind ( 86% ) of hospital acquired pneumonia . according to cdc definitions
, vap is an episode of pneumonia that develops more than 48 hours after initiation of mechanical ventilation[3 , 4 ] .
since the most important mechanism of vap is aspiration of colonized secretions in the nasopharynx , many attempts have been done to reduce colonization in trachea and nasopharynx[512 ] . in general , diagnosis of vap
other diagnostic tools like clinical , laboratory , imaging findings and examining the sputum qualitatively and quantitatively are limited too . thus neonatologists
utilize a combination of these techniques to diagnose vap according to their experience and setting .
newborns are more prone to vap because their mucosal layers are delicate , and their immune system is not completely functioning[2 , 13 ] .
it is stated that low birth weight , ventilators , frequent tracheal suctioning , sedation with opioids , and reintubation are directly associated with the incidence of vap .
recent data suggest that during mechanical ventilation , lateral positioning ( in which the endotracheal tube is horizontal ) may decrease the incidence of bacterial colonization of endotracheal tube[1619 ] .
the objective of this study was to evaluate the influence of lateral and supine position on bacterial colonization of endotracheal tube in neonates .
we conducted a prospective , randomized , clinical trial in the neonatal intensive care unit of 17 shahrivar children 's hospital of rasht ( rasht iran ) .
thirty - one intubated neonates ( intubated within 48 hours after birth ) were included ; 16 neonates were positioned supine ( supine group ) , and 15 were maintained in the lateral position ( lateral group ) .
sample size was chosen based on a similar study , indicating that 87% of neonates in supine position versus 30% of neonates in lateral position had bacterial colonization after 5 days .
so , two groups of 10 neonates would suffice to draw a conclusion . to increase the accuracy of the study , by increasing attrition rate , 31 newborns ( 16 in the supine and 15 in the lateral group )
participants were randomized by random fixed block method into two groups of a ( neonates in supine position ) and b ( neonates in lateral position ) .
inclusion criteria of this study were : 1 ) gestational age 28 weeks from the last menstrual period , 2 ) tracheal intubation at postnatal age of < 48 hours , 3 ) absence of congenital malformations such as tracheoesophageal fistulae , chest deformities or diaphragmatic hernia .
patients were excluded if they were diagnosed as congenital sepsis or pneumonia or they could not be maintained on mechanical ventilation for 5 full days .
we recorded demographic data and the results of routine laboratory tests that were performed for all neonates at the admission time in nicu from their files such as cbc , platelets , crp , abg ( arterial blood gas ) , blood cultures , and cxr .
patients were ventilated in simv mode using babylog 8000-plus drager ventilator with heated humidification system .
open method of suction was used for suctioning secretions as needed and no prophylactic topical oropharyngeal antibiotics and selective gut decontamination was done in any of the patients .
neonates in group a were maintained on their backs and endotracheal tube was held upright in a vertical position and their bed was kept horizontal with 10 degree head tilt ( routine care in our nicu ) .
group b subjects were positioned on their sides with the back supported by a rolled soft towel and they were alternatively rotated to left or right lateral position by trained nurses every two hours .
tracheal aspirates of both groups were cultured in second and fifth days of mechanical ventilation . for this purpose
the researcher wore sterile gloves and suctioned the endotracheal tube , using feeding tubes no 5 or 6 , without injecting any solution into the endotracheal tube and instantly transferred the samples into an emb agar and blood agar medium .
cultures were incubated for 24 hours in 37c . a single microbiologist blind to the grouping analyzed the dishes and studied the antibiogram .
abg variables and ventilator setup were recorded at second and fifth days of intubation from patients files too ( abg was performed for all intubated neonates daily in our setup ) .
data were analyzed with spss version 16 by tests of chi square , t - test and repeated measure anova .
the study protocol was approved by the ethical committee of guilan university of medical sciences .
in the second day of ventilation positive cultures were recognized in 6.2% ( 1 neonate ) of supine group and 6.7% ( 1 neonate ) of lateral group . after 5 days
tracheal cultures were positive in 25% ( 4 neonates ) of supine group and 13.3% ( 2 neonates ) of lateral group that was n't statistically significant ( p=0.9 in second and fifth day ) .
the most common organisms isolated from tracheal aspirates were gram - negative rods ( klebsiella ) .
table one gives comparison of weight , gestational age , and hours after birth , in the two groups .
there was not statistically difference between the two groups about initiation of feeding ( p=0.3 ) , use of h2 blocker ( p=0.9 ) and rate of reintubation ( p=0.6 ) .
because all the patients had respiratory distress at the time of admission , they all received antibiotic treatment according to unit policy .
except one patient with pneumothorax , other patients were intubated because of hyaline membrane disease . 
 
comparison of interfering parameters between supine and lateral position groups sd : standard deviation 
 table 2 shows the means of lab data of both groups in the first day of hospitalization .
we compared some abg variables and ventilator setup at the beginning , second day , and fifth day of mechanical ventilation in the two groups by t - test .
we also compared the trend in change of abg variables and ventilator setup in both groups using repeated measure anova .
the only exception was the means of po2 of the second and fifth day of ventilation that was higher in the supine group ( table 3 ) . 
 
means of lab data of both groups in the first day of hospitalization sd : standard deviation means of abg variables of second and fifth day after the initiation of mechanical ventilation abg : atrial blood gas ; sd : standard deviation
in our study bacterial colonization in endotracheal tube was not different in the two groups after two days .
colonization increased by the fifth day in both groups ( 6.7% to 13.3% in group b and 6.2% to 25% in group a ) .
the rate of increase in colonization from the second to the fifth day is higher in the supine positioned group ( group a ) .
aly et al also found an increased rate in the supine group yet it was statistically significant .
they selected 50 newborns with day five colonization count of 87% in the supine group and 30% in lateral positioned group .
our selection was 31 newborns with five day colonization count of 25% ( a ) versus 13% ( b ) .
the reason of this discrepancy is probably due to difference in study setting in terms of hand washing routines , lab techniques and hygiene .
it is to be noticed that some of our participants with the second day positive endotracheal cultures could not finish the study because of subsequent sepsis or pneumonia and death .
therefore , the real rate of colonization is expected to be higher than we found .
when the endotracheal tube is in vertical position , respiratory secretions passively enter to the lower airways .
therefore , eliminating the effect of gravity by maintaining the endotracheal tube in horizontal position should make respiratory secretions less likely to move down the airway .
in addition , we think that such positioning of the trachea facilitates sliding of respiratory secretions along the endotracheal tube wall and decreases the need for tracheal suctioning .
aly et al stated that reintubation rate in the supine group was more in their study and they mentioned this as one of the limitations of their study .
we can consider our groups to be more homogeneous in terms of newborns sex , hours from birth , gestational age , weight , type of delivery , and all laboratory indices .
the only exception was hb level that was more in the supine group ( group a ) ( mean hb level in group a was 15.88 g / dl and it was 14.36g / dl in group b which was significantly different ( p<0.02 ) ) .
in other words , positioning did not have any effect on po2 level because the supine group started the study by a higher level of hb .
differences in initiation of feeding and h2 blocker would adversely affect the result of the study , our groups were homogeneous in terms of initiation of feeding and h2 blocker .
balagur et al by a metaanalysis of 11 studies on the effect of safety in different positioning concluded that lateral position did not have any advantage over other positions , yet prone position had a better po2 level when compared with supine position .
ventilator setup was the same in both groups and fio2 was reduced as time passed and the trend was the same in both groups .
the most prevalent bacteria found in our study were gram negative rods among which klebsiella took precedence over pseudomonas and enterobacter .
afjeh from iran also reported that vap related organism was gram negative rods ( e. coli and then klebsiella ) more than other bacteria . 
 
frequency of bacterial growth in endotracheal tube in the two groups this was in accordance with tripathi et al and aly et al study[3 , 16 ] .
this reports indirectly confirm the importance of hand - washing in neonatal intensive care units , because the source of gram - negative rods is mainly environmental , primarily from the hands of staff members .
although we chose the sample size according the statistical formulas used in a similar study by aly et al , the frequency of colonization in our study was lower .
so , further studies with larger sample size are necessary to determine physiologic or clinical benefits of lateral position .
because endotracheal cultures were performed qualitative , we could not show the correlation of position and intensity of colonization .
in our study we surveyed the effect of position on bacterial colonization but not vap .
colonization of the endotracheal tubes is the main risk factors for vap , but it may occur separately with no symptoms or signs of vap .
although the colonization rate in lateral position group was 2 times less than in supine position group , because the difference was not statistically significant it needs to be confirmed by a larger sample study .
incidentally there is a negative attitude toward lateral positioning because the traditional position in all nicus is supine so some neonatologists were reluctant to cooperate with the intervention .
 objectiverecent data suggest that during mechanical ventilation , lateral patient position ( in which the endotracheal tube is horizontal ) decreases the incidence of bacterial colonization of ventilated neonates . 
 the objective of this study was to evaluate the influence of lateral and supine position on bacterial colonization of endotracheal tube in neonates.methodswe conducted a prospective , randomized , clinical trial with 31 intubated neonates ( intubated within 48 hours after birth ) ; sixteen neonates were positioned supine ( supine group ) , and fifteen were maintained in the lateral position ( lateral group).tracheal aspirates were cultured in second and fifth days of mechanical ventilation . 
 data were analyzed with spss version 16.findingsin the second day of ventilation , positive cultures were recognized in 6.2% of supine group and 6.7% of lateral group . 
 after 5 days , tracheal cultures were positive in 25% ( 4 neonates ) of supine group and 13.3% ( 2 neonates ) of lateral group that was n't statistically significant ( p=0.9 in second day and p=0.9 in the fifth day ) . 
 the most common organisms isolated from tracheal aspirates were gram - negative rods ( klebsiella).conclusionsince respiratory contamination is very common among ventilated neonates and the effect of lateral position on bacterial colonization of endotracheal tubes of intubated neonates was n't established in our study , further studies are required to suggest ways to decrease bacterial colonization of intubated neonates . 
Introduction
Subjects and Methods
Findings
Discussion
Conclusion
Conflict of Interest