- Email: [email protected]
The Artificial Placenta Rescues Premature Lambs from Ventilatory Failure
Vol. 225, No. 4S1, October 2017
survival. Previous studies have focused on neutrophil antimicrobial properties, but few have examined their ability to exit the bone marrow and reach the site of inflammation. To quantify the speed of migrating neutrophils, we utilized novel microfluidic approaches that require a single drop of blood. METHODS: Peripheral blood samples were collected from healthy, 1-day-old neonates and healthy, young adults. Neonates with prolonged rupture of membranes, chorioamnionitis, or evidence of infection were excluded. Microfluidic devices were employed, which circumvent the need for neutrophil purification. Ex vivo spontaneous neutrophil migration and neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine were measured with time-lapse imaging for 10 hours. For each sample, at least 20 neutrophils were tracked to calculate average speed. RESULTS: Twenty-three neonatal and 18 adult samples were collected (Figure). The mean gestational time and birth weight for neonates were 38.9 weeks and 3,353 grams, respectively. Compared with adults, neonates had 45% decreased speed of spontaneously migrating neutrophils (15.1 vs 21.5 m/min, p < 0.05). However, the speed of neutrophil chemotaxis to fMLP was comparable between neonates and adults (11.6 vs 12.7 mm/min).
Figure. Comparison of average speed of neutrophils from young adults and neonates.
CONCLUSIONS: Decreased spontaneous neutrophil migration in neonates may limit their sentinel activities and reduce their transit from bone marrow, but not affect their recruitment to sites of infection. How this affects host immunity is currently under investigation. Serotonin Reuptake Transporter Knockout Mice Exhibit Increased Enterocyte Mass and Intestinal Glucose Absorption Chasen J Greig, MD, Lucy Zhang, Robert A Cowles, MD, FACS Yale School of Medicine, New Haven, CT INTRODUCTION: Enteric serotonin is an integral neurotransmitter participating in a wide range of intestinal functions. Enhanced serotonin signaling occurs after genetic knockout of the serotonin reuptake transporter (SERT), which manifests in the intestine as increased crypt cell proliferation, neuroplasticity, and substantial anatomic increases in mucosal surface area. However, it remains unknown whether the above changes result in increased function. We hypothesized that serotonin-mediated mucosal growth would result in increases in enterocyte mass and absorptive function.
Scientific Forum Abstracts
S157
METHODS: After institutional approval, 10- to 12-week-old SERT-knockout (SERTKO) and wild-type (WT) C57Bl/6 mice were used for experiments. Plasma citrulline, a putative marker of enterocyte mass, was measured colorimetrically. Glucose absorption rate in perfused, isolated segments of proximal, middle, and distal small bowel was calculated using a previously described method involving instillation of glucose and a nonabsorbable substrate into the lumen for 15 minutes, with subsequent quantification of glucose remaining in aspirated contents after correction for fluid shifts. RESULTS: Plasma citrulline levels in SERTKO mice were significantly increased when compared to WT levels (Table). Glucose absorption in WT mice varied throughout the small intestine, with the highest rate in the proximal bowel. Compared with WT, SERTKO mice demonstrated increased glucose absorption in all regions of the bowel, with statistically significant increases in the middle and distal bowel (Table). Table. Mean SEM Values for Citrulline and Glucose Absorption Variable
Plasma citrulline (mM) Glucose absorption (mg/min) Proximal small bowel Middle small bowel Distal small bowel
Wild type
652 98
SERTKO
1,067 69
p Value
0.0059
5.01 0.50 6.11 0.03 0.0922 4.03 0.15 5.67 0.36 0.0135 2.82 0.57 5.82 0.17 0.0071
CONCLUSIONS: Enhanced serotonin signaling results in increased enterocyte mass and intestinal absorptive function. Taken together with previously demonstrated serotonin-mediated mucosal growth, these data further advance the concept that the serotonin system is an attractive therapeutic target for increasing functional intestinal mucosa. The Artificial Placenta Rescues Premature Lambs from Ventilatory Failure Joseph T Church, MD, Jennifer S McLeod, MD, Elena M Perkins, Robert H Bartlett, MD, George B Mychaliska, MD, FACS University of Michigan, Ann Arbor, MI INTRODUCTION: An artificial placenta (AP) utilizing extracorporeal life support (ECLS) would revolutionize the care of extremely premature neonates. In clinical application, neonates would likely undergo a trial of mechanical ventilation (MV) prior to AP support. We investigated the AP’s ability to rescue extremely premature lambs from failed MV. METHODS: Institutional Animal Care and Use Committee approval was obtained (protocol 00007211). Preterm fetal lambs at estimated gestational age (EGA) 116 to 121 days (term ¼ 145, n ¼ 3) were delivered via laparotomy and hysterotomy. The jugular vein and umbilical vein were cannulated and cannulas were clamped. Lambs were intubated, MV was initiated, and umbilical lines were placed. Surfactant was administered. Ventilation was continued for up to 1 hour, with failure defined as inability to
S158
J Am Coll Surg
Scientific Forum Abstracts
achieve pCO2 < 70, pO2 > 40, or SaO2 > 80. Upon failure, AP support was initiated with jugular venous drainage and umbilical vein reinfusion. The lungs were filled with perfluorodecalin for distention but not ventilation. Arterial blood gases (ABGs) were checked every 15 to 60 minutes. RESULTS: All 3 lambs failed MV; 1 became profoundly bradycardic after 30 minutes and had to be transitioned to AP support early. ABGs after 30 to 60 minutes of MV and then after 5 hours of AP support are shown in the Table. The AP normalized ABGs in all 3 animals. One lamb was subsequently supported with the AP for 11 days, transitioned to MV support and then room air, and decannulated on day 13. Table. Lamb
#1
#2
#3
ABG
MV (30e60 min)
AP (5 hrs)
pH pCO2 pO2 SaO2 pH pCO2 pO2 SaO2 pH pCO2 pO2 SaO2
6.86 142 32.7 57.6 6.81 128 5.9 3.3 6.85 154 33.6 62.3
7.38 42.9 32.9 65.0 7.27 46.9 34.4 74.5 7.45 32.8 39.6 75.9
Note: goal SaO2 60-75.
CONCLUSIONS: These data suggest that the AP may successfully rescue extremely premature lambs from failed MV. Furthermore, it appears feasible to continue support with successful weaning and transition to room-air breathing. Effect of Formal Pediatric Sub-Specialization on Surgical Outcomes in Children’s Surgery Katherine J Baxter, MD, Alexandra C Aiello, Mehul V Raval, MD Children’s Healthcare of Atlanta, Emory University, Atlanta, GA INTRODUCTION: Surgeons without formal pediatric training perform a significant proportion of children’s surgical care. Our purpose was to determine whether surgeon specialization in pediatric care is associated with improved outcomes. METHODS: The NSQIP database was used to conduct a retrospective cohort study of children (0 to 18 years) undergoing elective general, urologic, thoracic and spinal surgical procedures from 2012 to 2014. The primary outcome was composite morbidity and mortality, which included surgical site and infectious complications, reoperation, and 30-day readmissions. Logistic regression was used to estimate the primary outcome after adjusting for patient and procedural factors.
RESULTS: A total of 29,460 pediatric patients were identified as having undergone the procedures of interest. Operations were performed by pediatric sub-specialists in 94% of cases (n ¼ 27,570) (Table). In patients who underwent the general surgery procedures of gastrostomy, pyloromytomy, and cholecystectomy, surgeon specialization was not a significant predictor of composite morbidity. Similar results were seen in patients undergoing nephrectomy, non-nephrectomy urologic, thoracic, and spinal operations. Table. Composite Morbidity of Pediatric Surgeons vs. Adult Surgeons Bucket Gastrostomya,b Pyloromytomy2,b Cholecystectomyb Nephrectomy,3,a,b Non-Nephrectomy Urologica,b Thoracica,b Spinala
Number of Cases Performed by a Pediatric Specialist 3,954 (96.1%) 1,051 (97.6%) 3,093 (93.7%) 880 (93.2%)
Odds Ratio1 1.15 0.49 1.03 0.91
10,089 (92.2%) 1,631 (95.2%) 6,872 (95.0%)
0.89 0.81 0.89
95% Confidence interval 0.62 2.15 0.09 2.57 0.40 2.67 0.37 2.28 0.59 0.37 0.69
1.33 1.78 1.13
p Value 0.65 0.40 0.95 0.85 0.56 0.60 0.33
1: Odds ratios are based on multiple logistic regression using stepwise selection. Covariates considered for selection include: age group, sex, race, esophageal/gastric/intestinal disease, laparoscopic/MIS procedure, nutritional support, congenital malformation, bleeding disorders, hematological disorders, SIRS/Sepsis/Septic Shock within 48 hours prior to surgery, major cardiac risk factors, minor cardiac risk factors, weight loss or failure to thrive, diabetes mellitus requiring therapy with non-insulin agents or insulin, steroid use (within 30 days), seizure disorder, developmental delay/impaired cognitive status, blood transfusions within 48 hrs prior to surgery, acute renal failure, CVA/stroke or intracranial hemorrhage, ASA classification greater than or equal to 3, neuromuscular disorder, immune disease/immunosuppressant use, total operation time, and pre-operative WBC. 2: Age group removed from selection list. 3: Childhood Malignancy variable included in selection list. a: Age group forced into model. b: Laparoscopic/MIS procedure forced into model.
CONCLUSIONS: We did not observe a significant effect of surgeon specialization in pediatric care on composite morbidity for a variety of general, urologic, thoracic and spinal procedures. This suggests that individual surgeon volume and experience may be more important than formal pediatric training in determining outcomes for these operations. The Protective Role of TGF-b1 Administration in Neonatal Sepsis Alexandra C Bolognese, MD, Weng-Lang Yang, PhD, Jeffrey M Nicastro, MD, Gene F Coppa, MD, FACS, Wang Ping, MD Elmezzi Graduate School of Molecular Medicine, Hofstra Northwell School of Medicine, The Feinstein Institute for Medical Research, Manhasset, NY INTRODUCTION: Overall immaturity of the immune system puts neonates at increased risk for developing sepsis, which is
survival. Previous studies have focused on neutrophil antimicrobial properties, but few have examined their ability to exit the bone marrow and reach the site of inflammation. To quantify the speed of migrating neutrophils, we utilized novel microfluidic approaches that require a single drop of blood. METHODS: Peripheral blood samples were collected from healthy, 1-day-old neonates and healthy, young adults. Neonates with prolonged rupture of membranes, chorioamnionitis, or evidence of infection were excluded. Microfluidic devices were employed, which circumvent the need for neutrophil purification. Ex vivo spontaneous neutrophil migration and neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine were measured with time-lapse imaging for 10 hours. For each sample, at least 20 neutrophils were tracked to calculate average speed. RESULTS: Twenty-three neonatal and 18 adult samples were collected (Figure). The mean gestational time and birth weight for neonates were 38.9 weeks and 3,353 grams, respectively. Compared with adults, neonates had 45% decreased speed of spontaneously migrating neutrophils (15.1 vs 21.5 m/min, p < 0.05). However, the speed of neutrophil chemotaxis to fMLP was comparable between neonates and adults (11.6 vs 12.7 mm/min).
Figure. Comparison of average speed of neutrophils from young adults and neonates.
CONCLUSIONS: Decreased spontaneous neutrophil migration in neonates may limit their sentinel activities and reduce their transit from bone marrow, but not affect their recruitment to sites of infection. How this affects host immunity is currently under investigation. Serotonin Reuptake Transporter Knockout Mice Exhibit Increased Enterocyte Mass and Intestinal Glucose Absorption Chasen J Greig, MD, Lucy Zhang, Robert A Cowles, MD, FACS Yale School of Medicine, New Haven, CT INTRODUCTION: Enteric serotonin is an integral neurotransmitter participating in a wide range of intestinal functions. Enhanced serotonin signaling occurs after genetic knockout of the serotonin reuptake transporter (SERT), which manifests in the intestine as increased crypt cell proliferation, neuroplasticity, and substantial anatomic increases in mucosal surface area. However, it remains unknown whether the above changes result in increased function. We hypothesized that serotonin-mediated mucosal growth would result in increases in enterocyte mass and absorptive function.
Scientific Forum Abstracts
S157
METHODS: After institutional approval, 10- to 12-week-old SERT-knockout (SERTKO) and wild-type (WT) C57Bl/6 mice were used for experiments. Plasma citrulline, a putative marker of enterocyte mass, was measured colorimetrically. Glucose absorption rate in perfused, isolated segments of proximal, middle, and distal small bowel was calculated using a previously described method involving instillation of glucose and a nonabsorbable substrate into the lumen for 15 minutes, with subsequent quantification of glucose remaining in aspirated contents after correction for fluid shifts. RESULTS: Plasma citrulline levels in SERTKO mice were significantly increased when compared to WT levels (Table). Glucose absorption in WT mice varied throughout the small intestine, with the highest rate in the proximal bowel. Compared with WT, SERTKO mice demonstrated increased glucose absorption in all regions of the bowel, with statistically significant increases in the middle and distal bowel (Table). Table. Mean SEM Values for Citrulline and Glucose Absorption Variable
Plasma citrulline (mM) Glucose absorption (mg/min) Proximal small bowel Middle small bowel Distal small bowel
Wild type
652 98
SERTKO
1,067 69
p Value
0.0059
5.01 0.50 6.11 0.03 0.0922 4.03 0.15 5.67 0.36 0.0135 2.82 0.57 5.82 0.17 0.0071
CONCLUSIONS: Enhanced serotonin signaling results in increased enterocyte mass and intestinal absorptive function. Taken together with previously demonstrated serotonin-mediated mucosal growth, these data further advance the concept that the serotonin system is an attractive therapeutic target for increasing functional intestinal mucosa. The Artificial Placenta Rescues Premature Lambs from Ventilatory Failure Joseph T Church, MD, Jennifer S McLeod, MD, Elena M Perkins, Robert H Bartlett, MD, George B Mychaliska, MD, FACS University of Michigan, Ann Arbor, MI INTRODUCTION: An artificial placenta (AP) utilizing extracorporeal life support (ECLS) would revolutionize the care of extremely premature neonates. In clinical application, neonates would likely undergo a trial of mechanical ventilation (MV) prior to AP support. We investigated the AP’s ability to rescue extremely premature lambs from failed MV. METHODS: Institutional Animal Care and Use Committee approval was obtained (protocol 00007211). Preterm fetal lambs at estimated gestational age (EGA) 116 to 121 days (term ¼ 145, n ¼ 3) were delivered via laparotomy and hysterotomy. The jugular vein and umbilical vein were cannulated and cannulas were clamped. Lambs were intubated, MV was initiated, and umbilical lines were placed. Surfactant was administered. Ventilation was continued for up to 1 hour, with failure defined as inability to
S158
J Am Coll Surg
Scientific Forum Abstracts
achieve pCO2 < 70, pO2 > 40, or SaO2 > 80. Upon failure, AP support was initiated with jugular venous drainage and umbilical vein reinfusion. The lungs were filled with perfluorodecalin for distention but not ventilation. Arterial blood gases (ABGs) were checked every 15 to 60 minutes. RESULTS: All 3 lambs failed MV; 1 became profoundly bradycardic after 30 minutes and had to be transitioned to AP support early. ABGs after 30 to 60 minutes of MV and then after 5 hours of AP support are shown in the Table. The AP normalized ABGs in all 3 animals. One lamb was subsequently supported with the AP for 11 days, transitioned to MV support and then room air, and decannulated on day 13. Table. Lamb
#1
#2
#3
ABG
MV (30e60 min)
AP (5 hrs)
pH pCO2 pO2 SaO2 pH pCO2 pO2 SaO2 pH pCO2 pO2 SaO2
6.86 142 32.7 57.6 6.81 128 5.9 3.3 6.85 154 33.6 62.3
7.38 42.9 32.9 65.0 7.27 46.9 34.4 74.5 7.45 32.8 39.6 75.9
Note: goal SaO2 60-75.
CONCLUSIONS: These data suggest that the AP may successfully rescue extremely premature lambs from failed MV. Furthermore, it appears feasible to continue support with successful weaning and transition to room-air breathing. Effect of Formal Pediatric Sub-Specialization on Surgical Outcomes in Children’s Surgery Katherine J Baxter, MD, Alexandra C Aiello, Mehul V Raval, MD Children’s Healthcare of Atlanta, Emory University, Atlanta, GA INTRODUCTION: Surgeons without formal pediatric training perform a significant proportion of children’s surgical care. Our purpose was to determine whether surgeon specialization in pediatric care is associated with improved outcomes. METHODS: The NSQIP database was used to conduct a retrospective cohort study of children (0 to 18 years) undergoing elective general, urologic, thoracic and spinal surgical procedures from 2012 to 2014. The primary outcome was composite morbidity and mortality, which included surgical site and infectious complications, reoperation, and 30-day readmissions. Logistic regression was used to estimate the primary outcome after adjusting for patient and procedural factors.
RESULTS: A total of 29,460 pediatric patients were identified as having undergone the procedures of interest. Operations were performed by pediatric sub-specialists in 94% of cases (n ¼ 27,570) (Table). In patients who underwent the general surgery procedures of gastrostomy, pyloromytomy, and cholecystectomy, surgeon specialization was not a significant predictor of composite morbidity. Similar results were seen in patients undergoing nephrectomy, non-nephrectomy urologic, thoracic, and spinal operations. Table. Composite Morbidity of Pediatric Surgeons vs. Adult Surgeons Bucket Gastrostomya,b Pyloromytomy2,b Cholecystectomyb Nephrectomy,3,a,b Non-Nephrectomy Urologica,b Thoracica,b Spinala
Number of Cases Performed by a Pediatric Specialist 3,954 (96.1%) 1,051 (97.6%) 3,093 (93.7%) 880 (93.2%)
Odds Ratio1 1.15 0.49 1.03 0.91
10,089 (92.2%) 1,631 (95.2%) 6,872 (95.0%)
0.89 0.81 0.89
95% Confidence interval 0.62 2.15 0.09 2.57 0.40 2.67 0.37 2.28 0.59 0.37 0.69
1.33 1.78 1.13
p Value 0.65 0.40 0.95 0.85 0.56 0.60 0.33
1: Odds ratios are based on multiple logistic regression using stepwise selection. Covariates considered for selection include: age group, sex, race, esophageal/gastric/intestinal disease, laparoscopic/MIS procedure, nutritional support, congenital malformation, bleeding disorders, hematological disorders, SIRS/Sepsis/Septic Shock within 48 hours prior to surgery, major cardiac risk factors, minor cardiac risk factors, weight loss or failure to thrive, diabetes mellitus requiring therapy with non-insulin agents or insulin, steroid use (within 30 days), seizure disorder, developmental delay/impaired cognitive status, blood transfusions within 48 hrs prior to surgery, acute renal failure, CVA/stroke or intracranial hemorrhage, ASA classification greater than or equal to 3, neuromuscular disorder, immune disease/immunosuppressant use, total operation time, and pre-operative WBC. 2: Age group removed from selection list. 3: Childhood Malignancy variable included in selection list. a: Age group forced into model. b: Laparoscopic/MIS procedure forced into model.
CONCLUSIONS: We did not observe a significant effect of surgeon specialization in pediatric care on composite morbidity for a variety of general, urologic, thoracic and spinal procedures. This suggests that individual surgeon volume and experience may be more important than formal pediatric training in determining outcomes for these operations. The Protective Role of TGF-b1 Administration in Neonatal Sepsis Alexandra C Bolognese, MD, Weng-Lang Yang, PhD, Jeffrey M Nicastro, MD, Gene F Coppa, MD, FACS, Wang Ping, MD Elmezzi Graduate School of Molecular Medicine, Hofstra Northwell School of Medicine, The Feinstein Institute for Medical Research, Manhasset, NY INTRODUCTION: Overall immaturity of the immune system puts neonates at increased risk for developing sepsis, which is