Relationship Between Intraoperative Cerebral Desaturation and Postoperative Complications In Pediatric Patients Undergoing Congenital Heart Surgery: Prospective Cohort Study

Objective: In this study, we aimed to investigate the incidence of cerebral desaturation and the possible relationship between intraoperative cerebral desaturation and postoperative complications. Methods: A prospective, observational study was performed 115 patients under 18 years of age who required open heart surgery in a university hospital. Cerebral desaturation was defined as a 25% decrease in cerebral saturation (low alarm limit) when compared with the basal value. Duration (second) was referred to the amount of time the patient stays below low alarm limit. Depth (%) was referred to gap between the patient’s cerebral regional oxygen saturation (rSO2) level and the rSO2 low alarm limit. The cerebral desaturation score was calculated using the %*seconds. The patients were divided into two groups: group 1 (desaturation score >3000 %sec) and group 2 (desaturation score ≤ 3000 %sec). The groups were compared in terms of demographic data, intraoperative and postoperative variables, postoperative complications, and duration of intensive care and hospital stays. Results: In the study, 59 patients (51.3%) were male and 28 patients (24.3%) had cyanotic heart disease. A total of 55 patients (47.8%) experienced over 3000 %sec desaturation. Postoperative complications were found to be increased in group 1 (71% vs 3.3%; χ²=57.119, p<0.001). In the multiple logistic regression analysis, desaturation score>3000 %sec (p<0.001), low body surface area (p=0.001) and prolonged cardiopulmonary bypass (p=0.006) were found to be associated with postoperative complications. Conclusion: In patients undergoing congenital heart surgery, cerebral desaturation score >3000 %sec is associated with a negative effect on patient prognosis.

Changes in Electrical Activity of the Diaphragm in Response to Painful Procedures in Neonates

Background: Premature neonates are exposed to numerous painful procedures. Physiologic fluctuations in heart rate (HR), respiratory rate, and oxygen saturation are typically used to determine the response to pain. Neurally assisted ventilatory assist (NAVA) delivers inspiratory pressure in proportion to the electrical activity of the diaphragm (Edi). Since NAVA allows self-regulation of peak inspiratory pressures (PIP), there is apprehension that painful stimulus may increase respiratory drive and result in ex- cessive PIP. This study evaluated changes in respiratory drive, measured by Edi, in response to a painful procedure (heel stick) to determine if there was excessive PIP delivered from the ventilator. Methods: Prospective, single-center study; subjects <32 weeks on NAVA/NIV NAVA requiring routine blood work via heel sticks. Vital signs were measured every 10 seconds for the first 2 minutes. PIP, Edi peak, and min were collected for the first ten breaths and then averaged at 1 and 2 minutes. Statistics were repeated measures ANOVA. Results: Fourteen subjects with gestational age 26.9+2 weeks and birth weight 994+318 grams. At study, the average age was 4.6+5 days, and weight was 948+305 grams. Following the heel stick, the first breath showed an increase in PIP and Edi peak but returned to baseline by the second breath. PIP increased again by the10th breath and at 1 and 2 minutes. HR increased after heel stick and remained elevated through the remainder of the study. There were no changes in tonic Edi, Edi min or other vital signs. Conclusion: Although the increase in PIP and Edi peak in response to heel stick pain was brief and limited, it is important always to set the PIP alarm limit appropriately to protect the lung from excessive pressures that may be generated during painful procedures.

Reducing Alarm Fatigue in Two Neonatal Intensive Care Units through a Quality Improvement Collaboration

Objective To reduce nonactionable oximeter alarms by 80% without increasing time infants were hypoxemic (oxygen saturation [SpO2] ≤ 80%) or hyperoxemic (SpO2 > 95% while on supplemental oxygen). Study Design In 2015, a multidisciplinary team at Connecticut Children's Medical Center initiated a quality improvement project to reduce nonactionable oximeter alarms in two referral neonatal intensive care units (NICUs). Changes made through improvement cycles included reduction of the low oximeter alarm limit for specific populations, increased low alarm delay, development of postmenstrual age-based alarm profiles, and updated bedside visual reminders. Manual alarm tallies and electronic SpO2 data were collected throughout the project. Results Alarm tallies were collected for 158 patient care hours with SpO2 data available for 138 of those hours. Mean number of total nonactionable alarms per patient per hour decreased from 9 to 2 (78% decrease) and the mean number of nonactionable low alarms per patient per hour decreased from 5 to 1 (80% decrease). No change was noted in the balancing measures of percentage time with SpO2 ≤ 80% (mean 4.3%) or SpO2 > 95% (mean 23.7%). Conclusion Through small changes in oximeter alarm settings, including revision of alarm limits, alarm delays, and age-specific alarm profiles, our NICUs significantly reduced nonactionable alarms without increasing hypoxemia.

The Necessity of a Third Balance Plane for Generator Rotor Field Balancing

When balancing a generator rotor in the field, one often assumes that two balance planes at the drive end (DE) and non-driven end (NDE) fan rings would be sufficient to bring 1X vibration down. This paper, however, presents a case where a third balance plane must be utilized in order to reduce 1X vibration level below the alarm limit. Though this type of generator with rated speed of 3600 rpm appears to run just above the second couple mode from Bode and polar plots, couple weights (same weights placed at both DE and NDE with 180-degree out-of phase) have little effect on 1X vibration response. For vibration vectors at DE and NDE bearings presenting certain relative phase, it became impossible to further reduce vibration level at both ends from weights at DE and NDE fan ring planes only as indicated in obtained influence data. A third balance plane at the exciter end was attempted to change their relative phase, which proved to be successful. From the exciter end weights combined with the NDE fan ring weights, the generator rotor was balanced successfully. The purpose of this paper is to show in some cases ineffectiveness of couple weights to couple (pivotal mode) response and success of field balancing with a third balance plane on a generator rotor.

Wireless Temperature Measurement and Alarm Device Based on Single Bus Digital Temperature Sensor

AT89S52 microcontroller was the center controler for wireless temperature measurement and alarm system, through temperature measurement circuit and remote wireless alarm circuit, realized the temperature detection and off-limit alarm of the ambient temperature. The system was composed of temperature acquisition circuit, display circuit and alarm circuit. Temperature sensor was DS18B20, real-time temperature displayed via LED displayer. Users can customize the alarm lower limit and superior limit. when the ambient temperature exceeds the alarm limit, the microcontroller will start the sound and light alarm, and remote wireless alarm. Temperature measurement range from -40 °C to +85 °C, measurement accuracy is 0.5 °C, wireless alarm distance is up to 100 meters. This system is of high precision, wide temperature measurement, and timely alarm.