Desaturation Events Research Articles

The efficacy of apneic oxygenation to prevent hypoxemia during rapid sequence intubation in trauma patients.

Rapid and effective airway management is priority for trauma patients. Trauma patients are often at an increased risk of experiencing hypoxia, and thus at increased risk of morbidity and mortality. Apneic oxygenation has been widely debated but has been reported to provide benefit in terms of increased peri-intubation oxygen saturation and decreased rates of desaturation. This review aims to evaluate the current literature on the efficacy of apneic oxygenation in the setting of rapid sequence intubation (RSI) in trauma patients. Two prospective studies published this year, demonstrated that apneic oxygenation was effective in reducing hypoxic events and hypoxic duration during RSI. The use of apneic oxygenation can play an important role in preventing hypoxic events in trauma patients undergoing RSI. The use of apneic oxygenation is cheap, and should be considered to reduce hypoxemic events. Additional studies are required to see the effects of apneic oxygenation on outcomes in trauma patients undergoing RSI, specifically desaturation and hypoxemic events and duration, and early onset mortality.

Correlation Between Degree of Desaturation and Severity of Obstructive Sleep Apnoea: A Cross-sectional Study

Introduction: Obstructive Sleep Apnoea (OSA) is major Non Communicable Disease (NCD) which is becoming very common worldwide. The OSA results in day time hypersomnolence, nocturnal hypoxia and snoring. Repeated desaturation events during sleep results in aerobic metabolism at tissue level changing to anaerobic metabolism, which results in cellular inflammation and insulin resistance further complicating metabolic syndrome. Aim: To study correlation between degree of desaturation and severity of obstructive sleep apnoea. Materials and Methods: This cross-sectional study was conducted in Department of Pulmonary medicine at KS Hegde Medical Academy (tertiary care hospital), Mangaluru, Karnataka, India, from March 2018 to February 2021. Total 54 patients who underwent overnight polysomnography and diagnosed to have OSA were included in the study. The minimum recorded oxygen saturation (SpO2 ) defined as maximum desaturation was noted. Relative desaturation was defined as drop in saturation by 3% or more from the pre-event baseline. Correlation between total number of relative desaturation and Apnoea Hypopnea Index (AHI) was analysed. The correlation between two variables were analysed by Pearson’s correlation and the coefficient was calculated. The p-value was calculated by regression analysis and Analysis of Variance (ANOVA). Results: Total of 54 patients was included in the study. Out of which, 22 were mild, 14 moderate and 18 severe OSA respectively. Number of relative desaturations recorded was from 0 to 636. The correlation between AHI and mean SpO2 in sleep was r-value=-0.4542 (p-value=0.001) and the correlation between AHI and minimum SpO2 was r-value=-0.45577 (p-value=0.001) respectively. Correlation between mean SpO2 and minimum SpO2 was r-value=0.747266 (p-value<0.001) and the correlation between AHI and relative desaturation was r-value=0.876698 (p-value=0.001). Conclusion: As the severity of the obstructive sleep apnoea worsened, there was greater degree of desaturation in sleep and the lowest SpO2 was also observed during severe obstructive sleep apnoea.

Comparison of Efficacy of Premedication between Dexmedetomidine and Midazolam Intranasal for the Prevention of Emergence Delirium in Children Undergoing Ophthalmic Surgery.

Emergence delirium (ED) is a condition that can occur when a child recovers from anaesthesia uncomfortably. ED can potentially injure children and indirectly discomforts parents. Various interventions were carried out to reduce ED, but there is no specific standard that has been established to prevent ED. Dexmedetomidine and midazolam are said to be effective in reducing ED. This study aims to determine the effectiveness of intranasal dexmedetomidine premedication compared to intranasal midazolam to prevent ED in children undergoing eye surgery. This study was a double-blinded randomised clinical trial. Paediatric patients aged 1-12 years with physical status ASA 1 and 2 who underwent eye surgery under general anaesthesia using sevoflurane inhalation were included in the study. There were 64 children obtained by consecutive sampling who underwent eye surgery in our institution between February and May 2019. The subjects were then randomised into the dexmedetomidine group and the midazolam group. Effectiveness was assessed from ED events, recovery time and post-premedication desaturation events. Data analysis was performed using Chi-square test and Mann-Whitney test. ED incidence in the dexmedetomidine group was 11.18% compared to 28.12% in the midazolam group (P ¼ .109). The recovery time was found to be at a median of 6 minutes for both groups, and no desaturation was found in either group. There is statistically no significant difference between the effectiveness of intranasal dexmedetomidine and midazolam premedication 30 minutes before induction to prevent ED occurrence in children undergoing eye surgery.

Expiratory activity during sleep in children.

Sleep irregularities and respiratory events (apnea, O2 desaturation or a combination thereof) are often present in the infant population. While inspiration is the main active process in the act of breathing, expiration is generally thought to occur passively. Although commonly considered as quiet during sleep, expiratory abdominal muscles have been proposed to be recruited to promote ventilation, facilitate gas exchange, and reduce the work of breathing during conditions of increased respiratory drive, exercise, or airway obstruction. In this study, we investigated the occurrence of expiratory abdominal muscle activity in polysomnographic studies of subjects (aged 0-2years) suspected of sleep disordered breathing. Our results indicate that abdominal muscle activation occurs during sleep, most frequently during non-rapid eye movement and rapid-eye movement states compared to slow-wave sleep. Furthermore, abdominal muscle activity was present during regular breathing or associated with respiratory events (apneas or O2 desaturation). In the latter case, abdominal muscle recruitment more frequently followed the onset of respiratory events and terminated with recovery from blood O2 desaturation events. We conclude that expiratory abdominal muscle activity contributes to the pattern of respiratory muscle recruitment during sleep in infants and given its temporal relationship with respiratory events, we propose that its recruitment could facilitate proper ventilation by counteracting airway resistance and O2 desaturation in infancy across different stages of sleep.

Polysomnographic comparison of sleep in children with obesity and normal weight without suspected sleep-related breathing disorder.

Short sleep and obstructive apneas/hypopneas have been shown to be associated with childhood obesity. Still, few studies have compared sleep in children with obesity, without suspected sleep disordered breathing and normal weight peers by objective sleep measures and compared results with subjective parent assessment of sleep. Children with obesity aged 7-13 years (N= 44) and a matched group of normal weight children (N= 42) completed clinical polysomnography (Embla A10 Recording System). Parents scored their children's sleep on the Children's Sleep Habits Questionnaire (CSHQ). Mann-Whitney U tests were used to compare groups. There was a higher obstructive apnea/hypopnea index (AHI) (median obesity=1.20 vs. median normal =0.66; z= -1.33, U= 560.50, p= 0.002) and number of oxygen desaturation events per hour (median obesity=0.7 vs. median normal =0.2; z= -3.45, U= 402.50, p= 0.001) in the children with obesity compared to children with normal weight. The children with obesity had a significantly longer sleep duration (median obesity 8:50 h=vs. median normal=8:32 h; z= -2.05, U= 687.00, p= 0.041), longer stage N2 sleep (median obesity=87 min vs. median normal=52 min; z= -2.87, U= 576.50, p= 0. 004) and shorter REM sleep (median obesity=94 min vs. median normal=121 min; z= 5.05, U= 1477.00, p≤ .001). No differences were observed for time in sleep stage N1 and N3, wake time after sleep onset or the total arousal index . Further, no group differences were found on the CSHQ sleep-disordered breathing sub-scale (p= 0.399). The children with obesity demonstrated significantly more mild to moderate sleep disordered breathing than children with normal weight, although this was not corroborated by parent report.

Impact of High-Flow Nasal Cannula Oxygenation on the Prevention of Hypoxia During Endoscopic Retrograde Cholangiopancreatography in Elderly Patients: A Randomized Clinical Trial.

Hypoxia is the most frequently occurring adverse effect during endoscopic retrograde cholangiopancreatography (ERCP) under sedation; thus, oxygen must be properly supplied to prevent a reduction of oxygen saturation. In this study, we intend to verify the preventive effect for hypoxia during ERCP, using a high-flow nasal cannula (HFNC), in elderly patients. As a multicenter prospective randomized trial, patients who underwent ERCP with propofol-based sedation were randomly assigned into two groups: Patients in the HFNC group were supplied with oxygen via an HFNC, and those in the standard nasal cannula group were supplied with oxygen via a low-flow nasal cannula. The co-primary end points were the lowest oxygen saturation rate and hypoxia during the overall procedure. A total of 187 patients (HFNC group: 95; standard nasal cannula group: 92) were included in the analysis. Unexpected hypoxia events were more frequently observed among patients in the standard nasal cannula group than among patients in the HFNC group (13% vs. 4%, odds ratio 3.41, 95% confidence interval 1.06-11.00, p = 0.031). The mean of the lowest oxygen saturation rate during ERCP was significantly lower in the standard nasal cannula group than in the HFNC group (95% vs. 97%, p = 0.002). Oxygen supplementation with an HFNC can prevent oxygen desaturation and hypoxia events in patients undergoing ERCP under sedation. Trial registration Clinical Research Information Service (CRIS; KCT0004960).

Detection of Sleep-Disordered Breathing in Patients with Spinal Cord Injury Using a Smartphone.

Patients with spinal cord injury (SCI) have an increased risk of sleep-disordered breathing (SDB), which can lead to serious comorbidities and impact patients’ recovery and quality of life. However, sleep tests are rarely performed on SCI patients, given their multiple health needs and the cost and complexity of diagnostic equipment. The objective of this study was to use a novel smartphone system as a simple non-invasive tool to monitor SDB in SCI patients. We recorded pulse oximetry, acoustic, and accelerometer data using a smartphone during overnight tests in 19 SCI patients and 19 able-bodied controls. Then, we analyzed these signals with automatic algorithms to detect desaturation, apnea, and hypopnea events and monitor sleep position. The apnea–hypopnea index (AHI) was significantly higher in SCI patients than controls (25 ± 15 vs. 9 ± 7, p < 0.001). We found that 63% of SCI patients had moderate-to-severe SDB (AHI ≥ 15) in contrast to 21% of control subjects. Most SCI patients slept predominantly in supine position, but an increased occurrence of events in supine position was only observed for eight patients. This study highlights the problem of SDB in SCI and provides simple cost-effective sleep monitoring tools to facilitate the detection, understanding, and management of SDB in SCI patients.

Comparative evaluation of efficacy of oxygenation using high flow nasal cannula vs. conventional nasal cannula during procedural sedation for endoscopic ultrasound: A pilot study.

Background and Aims:High flow nasal cannula (HFNC) has numerous advantages against conventional oxygen therapy delivery systems. However, there is limited evidence supporting the use of HFNC in endoscopic ultrasound (EUS) under procedural sedation. The aims of this study is to evaluate the efficacy of two different oxygen delivery devices, that is,HFNCand conventional nasal cannula on the oxygenation status of patients during procedural sedation for EUS.Material and Methods:Sixty adult patients undergoing EUS for various ailments were randomized to two groups group HFNC (n=30) and group nasal cannula [NC (n = 30)]. HFNC (AIRVO2, Fisher and Paykel Healthcare, New Zealand) was used on patients in the group HFNC. Respiratory status of the patients was assessed using pulse oximetry, respiratory rate, procedural airway complications, and oxygen therapy adjustments. The endoscopist assessed the ease of performing EUS at the end of the procedure and patient satisfaction score (PSS) was assessed by using a Likert score in the post-anesthesia care unit.Results:SpO2 measurements in the HFNC group during the procedure were marginally better compared to the NC group but this failed to reach statistical significance. Also, no significant association was found between both groups while comparing desaturation events (P = 0.499), patient satisfaction score (PSS) and endendoscopist’s satisfaction score (ESS) (P = 0.795). Both the groups were comparable in terms of airway manipulation, use of airway adjuncts, need to increase oxygen flow rate, endoscope removal, apneic episodes, hypotension, and bradycardia. No major complications were observed in either group.Conclusion:HFNC use in patients undergoing EUS is not superior when compared to conventional nasal cannula oxygen therapy. HFNC failed to show any significant impact on decreasing the risk of desaturation events and airway manipulation during the procedure.

High flow versus conventional nasal cannula for oxygenation and ventilation maintenance during surgery with intravenous deep sedation by propofol: a randomized controlled study

BackgroundThe dead space washout and provision of some level of positive airway pressure by nasal high-flow (NHF) cannula could improve the efficiency of ventilation, oxygenation and maintenance of the upper airway in patients undergoing deep sedation. This study aimed to compare the incidences of events represented oxygenation and ventilation, i.e. desaturation and upper airway obstruction, and arterial blood gas (ABG) levels between using NHF cannula and conventional nasal cannula (NC2) during deep sedation of adult surgical patients.MethodsIn this prospective randomized single-blinded study, the patients who were 20–80 years old, ASA physical status of 1 to 3, scheduled for surgery under intravenous sedation (IVS) were included. The patients were randomly divided into two groups, i.e., NC2 or NHF groups. Propofol infusion was given to maintain deep sedation. The desaturation (SpO2 < 92%) and upper airway obstruction events (presence of snoring with paradoxical breathing) after application of NC2 or NHF were observed and collected. Other outcomes included interventions during IVS, such as jaw lifting or airway instrument insertion, mouth dryness, and post- ABG analyses were also collected and compared.ResultsThirty-six patients undergoing endovascular surgery were randomized into NC2 or NHF groups (18 in each group). No patients dropped out of the study. There were no significant differences in age, sex, ASA physical status, pre-sedation and pre-application of NC2 and NHF ABG analyses (PaO2, SaO2, pH, PaCO2, and PaO2/FiO2). NHF group had significantly lower in the incidence of desaturation [5 (27.78%) vs 13 (72.22%), p = 0.008], upper airway obstruction [4 (22.22%) vs 13 (72.22%), p = 0.003], and airway maneuver [6 (33.33%) vs 13 (72.22%), p = 0.019] than NC2 group. There were no differences in the ABG analyses after oxygen supplementation and no significant differences in mouth dryness between groups.ConclusionThe use of NHF cannula in patients undergoing endovascular surgery under deep sedation reduced desaturation events and required fewer airway interventions than NC2 with no difference in arterial blood gas analyses and mouth dryness.

Bedeutung patientenspezifischer Risikofaktoren für die regionale zerebrale Sauerstoffsättigung in „Beach-chair“-Position

Despite numerous studies on the regional cerebral oxygen saturation (rSO2) measured by near infrared spectroscopy (NIRS) in orthopedic patients in the beach chair position, it is still unclear whether patient-specific factors, such as concomitant cardiovascular diseases, are more frequently associated with the occurrence of cerebral desaturation events (CDE). The aim of the present study was therefore to identify possible patient-specific risk factors that enable prediction of CDE. Data were collected on 397 orthopedic patients undergoing shoulder surgery in the beach chair position. Routine anesthesia management and standard monitoring was used in all patients. Target value for the inspiratory oxygen concentration (FIO2) was set to 50% and for the end-tidal carbon dioxide partial pressure to 35-45 mm Hg. RSO2 was quantified using NIRS. The responsible anesthesiologist was blinded to the rSO2 data. Adecrease in rSO2 > 20% or avalue < 50% in the beach chair position was defined as CDE. Patients with and without CDE were analyzed with respect to different classifications, American Society of Anesthesiologists (ASA) and Revised Cardiac Risk Index (RCRI) as well as existing arterial hypertension and age. Avalue of p <0.05 was considered statistically significant. Patients with CDE (n = 238) were significantly more often classified as ASA > 2 (p = 0.01) and RCRI > 1 (p = 0.01), suffered more often from arterial hypertension (p = 0.01) and were older (median: 60 years compared to 55 years; p = 0.01) than patients without CDE (n = 159) in the beach chair position (Wilcoxon rank sum test). Arterial hypertension remained significant after removing the effect of age (p = 0.03) and RCRI classification (p = 0.04; two-way ANOVA multivariate analysis). On the basis of our study, patient-specific prognosis and risk factors for the occurrence of CDE, such as higher age, ASA > 2 and RCRI > 1 classification as well as pre-existing arterial hypertension could be determined. Arterial hypertension represents the main risk factor for the occurrence of CDE in the beach chair position. RCRI > 1 classification or age, however, only has an effect on the occurrence of pathological rSO2 values due to the greater probability of simultaneous arterial hypertension.

Percutaneous tracheostomy in COVID-19 patients: a new apneic approach

BackgroundPercutaneous dilation tracheostomy is an aerosol-generating procedure carrying a documented infectious risk during respiratory virus pandemics. For this reason, during the COVID-19 outbreak, surgical tracheostomy was preferred to the percutaneous one, despite the technique related complications increased risk. MethodsWe describe a new sequence for percutaneous dilation tracheostomy procedure that could be considered safe both for patients and healthcare personnel. A fiberscope was connected to a video unit to allow bronchoscopy. Guidewire positioning was performed as usual. While the established standard procedure continues with the creation of the stoma without any change in mechanical ventilation, we retracted the bronchoscope until immediately after the access valve in the mount tube, allowing normal ventilation. After 3 minutes of ventilation with 100% oxygen, mechanical ventilation was stopped without disconnecting the circuit. During apnea, the stoma was created by dilating the trachea and the tracheostomy cannula was inserted. Ventilation was then resumed. We evaluated the safeness of the procedure by recording any severe desaturation and by performing serological tests to all personnel. ResultsThirty-six patients (38%) of 96 underwent tracheostomy; 22 (23%) percutaneous dilation tracheostomies with the new approach were performed without any desaturation. All personnel (150 operators) were evaluated for serological testing: 9 (6%) had positive serology but none of them had participated in tracheostomy procedures. ConclusionThis newly described percutaneous dilation tracheostomy technique was not related to severe desaturation events and we did not observe any positive serological test in health workers who performed the tracheostomies.

SleepPos App: An Automated Smartphone Application for Angle Based High Resolution Sleep Position Monitoring and Treatment.

Poor sleep quality or disturbed sleep is associated with multiple health conditions. Sleep position affects the severity and occurrence of these complications, and positional therapy is one of the less invasive treatments to deal with them. Sleep positions can be self-reported, which is unreliable, or determined by using specific devices, such as polysomnography, polygraphy or cameras, that can be expensive and difficult to employ at home. The aim of this study is to determine how smartphones could be used to monitor and treat sleep position at home. We divided our research into three tasks: (1) develop an Android smartphone application (‘SleepPos’ app) which monitors angle-based high-resolution sleep position and allows to simultaneously apply positional treatment; (2) test the smartphone application at home coupled with a pulse oximeter; and (3) explore the potential of this tool to detect the positional occurrence of desaturation events. The results show how the ‘SleepPos’ app successfully determined the sleep position and revealed positional patterns of occurrence of desaturation events. The ‘SleepPos’ app also succeeded in applying positional therapy and preventing the subjects from sleeping in the supine sleep position. This study demonstrates how smartphones are capable of reliably monitoring high-resolution sleep position and provide useful clinical information about the positional occurrence of desaturation events.

Prophylactic measures to prevent cerebral oxygen desaturation events in elective beach-chair position shoulder surgeries: a systematic review and meta-analysis.

BackgroundProphylaxis for cerebral desaturation events (CDEs) during anesthesia in the beach chair position (BCP) for shoulder surgeries has not been evaluated. We systematically analyzed the effectiveness of various prophylactic measures used in this clinical setting.MethodsWe performed a meta-analysis (PROSPERO; no. CRD42020167285) of trials reporting CDEs and regional cerebral oxygen saturation (rSO2) and jugular venous oxygen saturation (SjvO2) values in anesthetized patients undergoing shoulder surgery in BCP. Considering the type of prophylactic measures used (pharmacological or non-pharmacological), a subgroup analysis was planned. Outcomes included (1) rSO2 and SjvO2 data with and without prophylactic measures for CDEs, recorded for different time intervals, and (2) the number of patients experiencing CDEs and hypotension. ResultsTwelve studies (786 patients) were included in the analysis. We observed lower absolute rSO2 values for early and all-time periods for vasoactive agent prophylaxis. The lowest achieved rSO2 values were also lower for vasoactive agent prophylaxis. Risk of CDEs was higher with vasoactive agent prophylaxis. Subgroup analysis identified targeted mild hypercarbia as effective in preserving cerebral oxygenation. Similarly, targeted mild hypercarbia prevented the fall in rSO2 with position change. Meta-regressions revealed statistically significant highest estimates for vasoactive agent prophylaxis in contrast to targeted mild hypercarbia. Likelihood of not developing CDEs was higher for targeted mild hypercarbia. In contrast to rSO2, most prophylactic methods reduced hypotensive episodes. ConclusionsTargeted mild hypercarbia can reduce BCP-related CDEs. Evidence does not favor prophylactic use of vasoactive agents for the prevention of cerebral desaturations irrespective of whether their use interferes with cerebral oximetry readings.

Polysomnography parameters as predictors of respiratory adverse events following adenotonsillectomy in children

The first-line treatment of obstructive sleep apnea syndrome in children is adenotonsillectomy, but this may result in perioperative respiratory adverse events (PRAEs). The primary aim of this study is to examine whether the McGill oximetry score (MOS) and other polysomnography parameters can predict major PRAEs following adenotonsillectomy. We secondarily evaluated the MOS interrater reliability and correlation with other polysomnography parameters. This retrospective study included all children aged 0-18 years who underwent preoperative polysomnography between June 2010 and January 2016 prior to adenotonsillectomy at a tertiary pediatric institution. Oximetries from polysomnograms were assigned an MOS. Univariable and multivariable models for prediction of major PRAEs were constructed. MOS was correlated with polysomnography parameters and interrater reliability was evaluated. This study included 106 children; 15 had a major PRAE. A multivariable prediction model that combined MOS and age showed evidence for the ability to predict major PRAEs with an area under the receiver operating characteristic curve of 0.68 (95% confidence interval: 0.52, 0.84), whereby increased MOS and younger age were associated with PRAEs, but apnea-hypopnea index was not. MOS had excellent interrater reliability (κ = 0.95) and was highly correlated with oxygen saturation nadir and cumulative time percentage with oxygen saturation less than 90%. A prediction model including MOS and age may predict PRAEs following adenotonsillectomy. This suggests that nocturnal oximetry provides the most essential information of polysomnography measures to direct postoperative monitoring following adenotonsillectomy. Xiao L, Barrowman N, Momoli F, etal. Polysomnography parameters as predictors of respiratory adverse events following adenotonsillectomy in children. J Clin Sleep Med. 2021;17(11):2215-2223.

Effects of dexmedetomidine sedation for magnetic resonance imaging in children: a systematic review and meta-analysis.

Pediatric sedation is commonly required to obtain high-quality images in magnetic resonance imaging (MRI). We performed a systematic review and meta-analysis to assess the effects of dexmedetomidine sedation for MRI in children. A systematic review was conducted to find all randomized controlled trials concerning dexmedetomidine sedation for MRI in children. We searched databases using the Ovid platform in the Cochrane Controlled Trials Register, MEDLINE, and EMBASE. This study was registered in the PROSPERO database: CRD42020198368. Seven studies and 753 participants were included. Dexmedetomidine sedation showed a significantly delayed onset time [weighted mean differences (WMD) = 8.13min, 95% confidence interval (CI) 4.64 to 11.63, I2 = 98%] and recovery time (WMD = 5.22min, 95% CI 0.35 to 10.09, I2 = 92%) compared to propofol, ketamine, and midazolam sedation. There was no difference in quality of sedation [risk ratio (RR) = 1.25, 95% CI 0.92 to 1.69, I2 = 89%], or incidence of sedation failure (RR = 1.39, 95% CI 0.53 to 3.66, I2 = 83%) between groups. Although a significantly decreased heart rate (WMD = - 17.34 beats/minute, 95% CI - 22.42 to - 12.26, I2 = 96%) was observed, bradycardia that required treatment was not increased (RR = 8.00, 95% CI 1.02 to 62.64, I2 = 0%). Dexmedetomidine sedation had a lower incidence of desaturation events (RR = 0.42, 95% CI 0.20 to 0.86, I2 = 4%). However, there was no difference in incidence of postoperative vomiting (RR = 0.42, 95% CI 0.15 to 1.17, I2 = 17%) between groups. Dexmedetomidine sedation provided a similar sedation quality with a reduced incidence of desaturation events. However, the delayed onset and recovery times were drawbacks. The clinical significance of bradycardia is considered to be low. GRADE assessment revealed the quality of the evidence in this meta-analysis ranged from very low to moderate.

Associations between nocturnal continuous blood pressure fluctuations and the characteristics of oxygen desaturation in patients with obstructive sleep apnea: a pilot study

BackgroundPatients with obstructive sleep apnea (OSA) frequently experience apnea-related oxygen desaturation events (ODE) accompanied by striking blood pressure (BP) fluctuations during sleep. We aimed to investigate the effects of characteristics of ODE on nocturnal BP fluctuations in OSA patients. Methods and resultsA total of 6199 ODE were obtained from 30 patients with who underwent overnight portable monitoring and beat-to-beat BP monitoring simultaneously. The associations between nocturnal BP parameters and the characteristics of ODE were studied. The mean value of systolic BP (SBP) monitored during ODE was higher than the non-hypoxia SBP value (122.0 ± 15.9 vs. 120.4 ± 15.1 mmHg, P = 0.001) and nighttime SBP value (122.0 ± 15.9 vs. 120.8 ± 15.0 mmHg, P = 0.002). SBP variability (SBPV) during ODE was higher than the values not during ODE (14.0 ± 2.8 vs. 13.2 ± 2.6 mmHg, P = 0.043) and nighttime SBPV (14.0 ± 2.8 vs. 12.9 ± 2.3 mmHg, P < 0.001). Hypoxia SBP index, defined as the percentage of SBP surge (△SBP) ≥10 mmHg to all △SBP during ODE, increased with greater respiratory event index (P = 0.01). Both the coefficient of variation for SBP values of an ODE (SBPV′) and event-related SBP elevation (△SBP′) increased with raised amplitude of ODE (P < 0.001 for SBPV′ and P < 0.001 for △SBP′). Similar results were observed when the duration of events was analyzed (P < 0.001 for SBPV′ and P < 0.001 for △SBP′). ConclusionBP related to ODE may be the main component of increased BP during sleep in OSA patients. In addition to the frequency of respiratory events, the amplitude and duration of ODE may have a role in nocturnal BP fluctuations in OSA patients.

393 Comparison of Oxygenation Abnormalities Between Obstructive Sleep Apnea and Central Sleep Apnea

Abstract Introduction The apnea-hypopnea index (AHI) is used as a generic index to quantify both central sleep apnea (CSA) and obstructive sleep apnea (OSA) syndromes. Patterns of oxygenation abnormalities seen in CSA and OSA may be key to understanding differing clinical impacts of these disorders. Oxygen desaturation and resaturation slopes and durations in OSA and CSA were compared between OSA and CSA patients. Methods Polysomnographic data of patients aged 18 years or older with diagnosis of OSA and CSA, at University of Iowa Hospitals and Clinics, were analyzed and demographic data were collected. Oximetric changes during hypopneas and apneas were studied for desaturation/resaturation durations and desaturation/resaturation slopes. Desaturation and resaturation slopes were calculated as rate of change in oxygen saturation (ΔSpO2/Δtime). Comparison of hypoxemia-based parameters between patients with OSA and CSA was performed using unpaired t-test. Results 32 patients with OSA with median AHI of 15.4 (IQR 5.1 to 30.55) and median ODI of 15.47 (IQR 9.50 to 29.33) were compared to 15 patients with CSA with a median AHI of 20.4 (IQR 12.6 to 47.8) and median ODI of 27.56 (IQR 17.99 to 29.57). The mean number of desaturation and resaturation events was not significantly different between patients with OSA and CSA (OSA - 106.81±87.93; CSA - 130.67±76.88 with a p-value 0.1472). 4/15 CSA patients had Cheyne-Stokes breathing, 2/15 had treatment emergent central sleep apnea, 1/15 had methadone-associated CSA and for 8/15, no etiologies for CSA were found. Mean desaturation durations was significantly longer in OSA (20.84 s ± 5.67) compared to CSA (15.94 s ± 4.54) (p=0.0053) and consequently the desaturation slopes were steeper in CSA than OSA (-0.35%/sec ±0.180 vs. -0.243 ± 0.073; p=0.0064). The resaturation duration was not significantly longer in OSA (9.76 s ± 2.02) than CSA (9.057 s ± 2.17) (p=0.2857). Differences between desaturation duration and slopes between CSA and OSA persisted during REM and NREM sleep, and in supine sleep. Conclusion As compared to OSA, patients with CSA have different patterns of desaturations and resaturations with lesser hypoxic burden with CSA. This may have implications on the clinical outcomes seen between these two disorders. Support (if any):

Study of Obstructive Sleep Apnea Parameters in Patients of Nasal Polyposis Using Peripheral Arterial Tonometry

Background: Obstructive sleep apnea (OSA) syndrome is characterized by partial or complete cessation of airflow and oxygen desaturation during sleep owing to upper airway collapse. This study assesses the OSA parameters in nasal polyposis patients before and after functional endoscopic sinus surgery (FESS) with the help of peripheral arterial tonometry (PAT) device. Methodology: This was a prospective study done in the months of April 2015 to June 2016. Patients with bilateral nasal polyps with Lund Mackay Scoring marking equal to and more than two of both sides. Thirty patients willing to undergo PAT sleep study before and after FESS were recruited. The sleep parameters thus obtained in the pre- and postoperative period were analyzed. Results: Out of 30 patients, 22 patients were male and eight patients were female. The mean age was 43.17 with standard deviation of 10.06 years. The mean body mass index was 29.12 with a standard deviation of 5.76. All patients underwent FESS. The PAT study was done before and after surgery. Snoring grading and Epworth Sleepiness Scale scoring improved in the majority of patients after surgery. The mean respiratory disturbance index (RDI) in the preoperative period was 32.7 which decreased to 11.34 in the postoperative period. The mean apnea hypopnea index (AHI) in the preoperative period was 22.85 which decreased to 6.34 in the postoperative period. The mean oxygen desaturation index (ODI) in the preoperative period was 16.8 which decreased to 4.4 after surgery. Significant correlation (P &lt; 0.001) was found between pre- and postoperative RDI, AHI, ODI, and oxygen desaturation events. Conclusion: The OSA parameters before and after endoscopic sinus surgery in nasal polyposis patients got improved. The PAT device, which is the newest novel plethysmograph, proved to be a reliable device for the assessment of sleep apnea parameters in nasal polyposis in the pre- or postoperative period.

Vital sign metrics of VLBW infants in three NICUs: implications for predictive algorithms.

Background:Continuous heart rate (HR) and oxygenation (SpO2) metrics can be useful for predicting adverse events in very low birth weight (VLBW) infants. To optimize the utility of these tools, inter-site variability must be taken into account.Methods:For VLBW infants at three NICUs, we analyzed the mean, standard deviation, skewness, kurtosis, and cross-correlation of electrocardiogram HR, pulse oximeter pulse rate, and SpO2. The number and durations of bradycardia and desaturation events were also measured. Twenty-two metrics were calculated hourly, and mean daily values were compared between sites.Results:We analyzed data from 1,168 VLBW infants from birth through day 42 (35,238 infant-days). HR and SpO2 metrics were similar at the three NICUs, with mean HR rising by ~10 beats/minute over the first two weeks and mean SpO2 remaining stable around 94% over time. The number of bradycardia events was higher at one site, and the duration of desaturations was longer at another site.Conclusion:Mean HR and SpO2 were generally similar among VLBW infants at three NICUs from birth through six weeks of age, but bradycardia and desaturation events differed in the first two weeks after birth. This highlights the importance of developing predictive analytics tools at multiple sites.

P0400 / #988: ADVERSE EVENTS AND PRACTICE VARIABILITY ASSOCIATED WITH PEDIATRIC ENDOTRACHEAL SUCTION: AN OBSERVATIONAL STUDY

Aims & Objectives: To determine the incidence of endotracheal tube (ETT) suction related adverse events (AEs) and to examine associations between AEs and patient and suction characteristics. Secondary objectives was to describe ETT suction practices in an Australian paediatric intensive care unit (PICU). Methods: A prospective, observational study was undertaken in a 36-bed PICU. Children were eligible for inclusion if they were intubated and mechanically ventilated. Data on patient and suction variables (e.g. indication for ETT suction, normal saline instillation (NSI)) including potential predictive variables (age, severity of illness, NSI, hyperoxygenation) were collected. The main outcome variable was a composite measure of any AE. Results: In total 955 suction episodes were recorded in 100 children. AEs occurred in 211 (22%) ETT suctions and were not associated with age, diagnostic category or mortality score. Desaturation was the most common AE (180 suctions; 19%), with 69% of desaturation events requiring clinician intervention. Univariate logistic regression showed the odds of desaturation decreased as the internal diameter of the ETT increased (OR 0.59; 95%CI 0.37-0.95; p= 0.028). Multivariable modelling revealed NSI was significantly associated with increased risk of desaturation (adjusted OR [aOR] 3.23; 95%CI 1.99-5.40; p<0.001) and the occurrence of an AE (aOR 2.76; 95%CI1.74-4.37; p<0.001). Pre- suction increases in fraction of inspired oxygen (FiO2) were associated with an increased risk of AE (aOR 2.0; 95%CI1.27-3.15; p = 0.003). Conclusions: Prospective trial data are needed to determine the efficacy of suction interventions such as NSI. Improved evidence can inform evidence based guidelines which reduce variations in care and suction related AEs.