- Email: [email protected]
Optimizing fluid resuscitation in hypertrophic pyloric stenosis
Journal of Pediatric Surgery xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Journal of Pediatric Surgery journal homepage: www.elsevier.com/locate/jpedsurg
Optimizing fluid resuscitation in hypertrophic pyloric stenosis Brian G.A. Dalton a, Katherine W. Gonzalez a, Sushanth R. Boda a, Priscilla G. Thomas a, Ashley K. Sherman b, Shawn D. St. Peter a,⁎ a b
Department of Pediatric Surgery, Children's Mercy Hospital, Kansas City, MO Department of Research Development and Clinical Investigation, Children's Mercy Hospital, Kansas City, MO
a r t i c l e
i n f o
Article history: Received 5 October 2015 Received in revised form 21 December 2015 Accepted 21 January 2016 Available online xxxx Key words: Hypertrophic pyloric stenosis Electrolyte abnormalities Fluid resuscitation Chloride Bicarbonate Pyloromyotomy
a b s t r a c t Background: Hypertrophic pyloric stenosis (HPS) is the most common diagnosis requiring surgery in infants. Electrolytes are used as a marker of resuscitation for these patients prior to general anesthesia induction. Often multiple fluid boluses and electrolyte panels are needed, delaying operative intervention. We have attempted to predict the amount of IV fluid boluses needed for electrolyte correction based on initial values. Methods: A single center retrospective review of all patients diagnosed with HPS from 2008 through 2014 was performed. Abnormal electrolytes were defined as chloride b100 mmol/L, bicarbonate ≥30 mmol/L or potassium N 5.2 or b3.1 mmol/L. Patients with abnormal electrolytes were resuscitated with 20 ml/kg saline boluses and continuous fluids at 1.5 times maintenance rate. Results: During the study period 542 patients were identified with HPS. Of the 505 who were analyzed 202 patients had electrolyte abnormalities requiring IV fluid resuscitation above maintenance, and 303 patients had normal electrolytes at time of diagnosis. Weight on presentation was significantly lower in the patients with abnormal electrolytes (3.8 vs 4.1 kg, p b 0.01). Length of stay was significantly longer in the patients with electrolyte abnormalities, 2.6 vs 1.9 days (p b 0.01). Fluid given was higher over the entire hospital stay for patients with abnormal electrolytes (106 vs 91 ml/kg/d, p b 0.01). The number of electrolyte panels drawn was significantly higher in patients with initial electrolyte abnormalities, 2.8 vs 1.3 (p b 0.01). Chloride was the most sensitive and specific indicator of the need for multiple saline boluses. Using an ROC curve, parameters of initial Cl− 80 mmol/L and the need for 3 or more boluses AUC was 0.71. Modifying the parameters to initial Cl− ≤97 mmol/L and 2 boluses AUC was 0.65. A patient with an initial Cl− 85 will need three 20 ml/kg boluses 73% (95% CI 52–88%) of the time. A patient with an initial Cl− ≤97 will need two 20 ml/kg boluses at a rate of 73% (95% CI 64–80%). Conclusion: Children with electrolyte abnormalities at time of diagnosis of HPS have a longer length of stay; require more fluid resuscitation and more lab draws. This study reveals high sensitivity and specificity of presenting chloride in determining the need for multiple boluses. We recommend the administration of two 20 ml/kg saline boluses separated by an hour prior to rechecking labs in patients with initial Cl− value ≤97 mmol/L. If the presenting Cl− b 85 three boluses of 20 ml/kg of saline separated by an hour are recommended. If implemented these modifications have potential to save time by not delaying care for extraneous lab results and money in the form of fewer lab draws. © 2016 Elsevier Inc. All rights reserved.
1. Background Hypertrophic pyloric stenosis (HPS) is the most common diagnosis requiring surgery in infants. Electrolytes are used as a marker of resuscitation for these patients prior to general anesthesia induction. Typically, if electrolyte abnormalities (Cl − b 100 mmol/L, HCO3 ≥30 mmol/L, or K + ≤3.4 or ≥5.2 mmol/L) are present on diagnosis of pyloric stenosis, aggressive intravenous fluid resuscitation is given. Often multiple electrolyte panels are needed to assess correction, delaying operative intervention. We have attempted to predict the amount of IV
⁎ Corresponding author at: Children's Mercy Hospital, Department of Surgery, 2401 Gillham Rd., Kansas City, MO 64108. Tel.: +1 816 983 6465; fax: +1 816 983 6885. E-mail address: [email protected] (S.D. St. Peter).
fluid resuscitation needed for electrolyte correction based on initial values. We hypothesized that patients with HPS and abnormal electrolytes would require more than standard fluid resuscitation to correct electrolytes prior to pyloromyotomy, and a review of retrospective data would be able to provide a starting point for a more efficient fluid resuscitation strategy. 2. Methods After approval from the Children's Mercy Hospital Internal Review Board (IRB # 13070217) a single center retrospective chart review was performed. All patients diagnosed with HPS from 2008 through 2014 were considered. Patients were excluded for insufficient data in medical records, or if electrolyte abnormalities were atypical for HPS.
http://dx.doi.org/10.1016/j.jpedsurg.2016.01.013 0022-3468/© 2016 Elsevier Inc. All rights reserved.
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013
2
B.GA. Dalton et al. / Journal of Pediatric Surgery xxx (2016) xxx–xxx
Table 1 Demographic data.
Age (weeks) Gender (%male) Weight (kg) Pylorus length (cm) Pylorus diameter (cm)
Table 2 Initial Cl− and need for saline boluses prior to electrolyte correction. Abnormal electrolytes (n = 202)
Normal electrolytes (n = 303)
p
5.6 83 3.8 2.0 0.4
5.4 84 4.1 2.0 0.4
0.44 0.58 b0.01 0.64 0.19
# of 20 ml/kg boluses
3
2
Data are presented as mean ± standard deviation unless otherwise stated. Significance is defined as p ≤ 0.05. Comparative analysis was performed using Student t test for continuous variables and Fisher exact for binary variables or chi square test with Pearson correlation where appropriate. Area under the curve (AUC) was calculated using receiver operating characteristic (ROC) curve. Abnormal electrolytes were defined as chloride b100 mmol/L, bicarbonate ≥30 mmol/L or potassium N 5.2 or b 3.1 mmol/L. Maintenance fluid given was 5% dextrose in 0.45% saline with or without the addition of potassium dependent on the patient's potassium level and urine output. All patients were administered 1.5× maintenance fluids if abnormal electrolytes or urine output was present (b 1 ml/kg/h). All boluses of fluid were given in the form of normal saline. It is our practice for labs to be drawn 1 h after the conclusion of a fluid bolus. 3. Results During the study period 542 patients were identified with pyloric stenosis. Twenty six were excluded to owing to lack of data in the medical record. Eleven were analyzed separately as the electrolyte abnormalities were atypical for pyloric stenosis. Five-hundred five patients were analyzed. All surgeries were performed laparoscopically. Twohundred two of these patients had electrolyte abnormalities requiring IV fluid resuscitation above maintenance, and 303 patients had normal electrolytes at time of diagnosis. Demographic data for these two groups are shown in Table 1.
Cl− value (mmol/L) b70 (n b80 (n b85 (n b90 (n ≤95 (n ≤97 (n
= = = = = =
5) 11) 26) 49) 106) 132)
Sensitivity (%)
Specificity (%)
p
95% CI
100 90.9 73.1 77 71.7 72.7
74.1 75.9 79 80.5 44.8 52.9
0.001 b0.001 b0.001 b0.001 0.02 b0.001
46–100 57–99 52–88 63–87 62–80 64–80
Weight on presentation was significantly lower in the patients with abnormal electrolytes (Table 1). Total length of stay was significantly longer in the patients with electrolyte abnormalities, 2.6 vs 1.9 days (p b 0.001). Fluid given was higher over the entire hospital stay for patients with abnormal electrolytes (106 vs 91 ml/kg/d, p b 0.001). The number of electrolyte panels drawn was significantly higher in patients with initial electrolyte abnormalities, 2.8 vs 1.3 (p b 0.001). The current cost of basic metabolic panel is $105 at our institution. The total cost for basic metabolic panels in the patients with abnormal electrolytes was $59,388 versus $41,360 for those without electrolyte abnormalities. That difference is $18,000 despite the normal electrolyte group having 101 more patients. Average chloride value for patients with abnormal electrolytes was 93 ± 8.4 mmol/L. Twenty six patients presented with a normal chloride level (≥100 mmol/L) but an abnormal chloride level (≥30 mmol/L). Mean bicarbonate on presentation of patients with abnormal electrolytes was 32.5 ± 5.2 mmol/L. Thirty nine patients presented with normal bicarbonate level (b30 mmol/L) and an abnormal chloride level (b 100 mmol/L). Sixty four percent (130 of 202) of patients with abnormal electrolytes on presentation required multiple 20 ml/kg normal saline boluses. Both chloride (Cl−) and bicarbonate (HCO3) were useful markers in determining the number of 20 ml/kg normal saline boluses a patient would require prior to electrolyte normalization (Cl− ≥100, HCO3−b30, K + ≥ 3.4 b5.2 mmol/L). Using a ROC curve, parameters of initial Cl b 80 mmol/L and the need for 3 or more boluses AUC was 0.71 (Fig. 1). Modifying the parameters to initial Cl ≤97 mmol/L and 2 boluses AUC was 0.65. When initial HCO3 ≤ 33 mmol/L and the need for 2 or more boluses are considered AUC was 0.66. Sensitivity and specificity values correlated to variable values of both Cl− and HCO3 are shown in Tables 2 and 3. As seen in the tables, chloride is the more sensitive and specific electrolyte in the gauging the fluid resuscitation needs of a patient with pyloric stenosis. The total fluid required for correction of electrolytes based on initial chloride and bicarbonate values are shown in Figs. 2 and 3 with a linear regression model. Initial potassium value was not useful in guiding fluid resuscitation. Only 13.5% of patients presented with abnormal potassium not owing to hemolysis, 4.5% had a low value and 9.9% with an abnormally high value. Eleven patients (2.2%) were found to have electrolyte abnormalities atypical for pyloric stenosis. All 11 patients were found to have a low bicarbonate level b22 mmol/L (mean 17.8 ± 1.9). Two patients were found to have an elevated chloride level (N111 mmol/L). Nine patients were found to have a normal chloride level on initial evaluation. Nine of eleven patients did receive at least one bolus of 20 ml/kg normal saline.
Table 3 Initial HCO3 and need saline boluses prior to electrolyte correction. # of 20 ml/kg boluses 3 Fig. 1. ROC curve of the need for 3 or more 20 ml/kg saline boluses to normalize electrolytes if initial Cl− b80 mmol/L.
2
HCO3 value (mmol/L)
Sensitivity (%)
Specificity (%)
p
95% CI
≥45 (n ≥40 (n ≥35 (n ≥33 (n ≥31 (n
83.3 68.4 82 77.1 70.6
72.7 77 41.4 44.5 46.1
0.009 b0.001 0.003 0.002 0.02
36–99 43–86 68–91 66–85 62–78
= = = = =
6) 19) 50) 83) 126)
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013
B.GA. Dalton et al. / Journal of Pediatric Surgery xxx (2016) xxx–xxx
3
Fig. 2. IV fluid required for normalization of Cl−.
4. Discussion Abnormal chloride and bicarbonate on presentation have been previously correlated with longer time to goal feeds, often the limiting step in discharge of a patient after successful pyloromyotomy [1]. Our findings are in agreement with this as patients with electrolyte abnormalities had a significantly longer length of stay than those with normal electrolytes at the time of presentation. Postoperative feeding regimens have been studied well [2–5]. However, there is little evidence to guide the amount of fluid resuscitation needed in pyloric stenosis prior to electrolyte normalization in preparation for pyloromyotomy [5]. There has been evidence to characterize the rate of electrolyte abnormality correction with a particular fluid resuscitation protocol [6]. Our current practice is to administer a bolus of 20 ml/kg normal saline in a patient diagnosed with pyloric stenosis and then recheck electrolytes. When the patient is not receiving a bolus intravenous 5% dextrose in 0.45% saline is with or without potassium administered at a rate of 1.5 times maintenance rate. With the data presented here, we will plan a change in practice. This will include the use of chloride as the most sensitive indicator to guide resuscitation. Our data show that nearly 73% of patients with an initial chloride less than 97 mmol/L will require at least 2 boluses of 20 ml/kg of saline. In this situation we plan to provide 40 ml/kg of saline for initial resuscitation while keeping the
continuous rate at 1.5 times maintenance when the patient is not receiving a bolus. If the chloride is less than 85 mmol/L 60 ml/kg will be administered in the form of 3 boluses. If chloride is normal, but bicarbonate is abnormal then the cutoffs for 40 and 60 ml/kg would be 33 and 40 mmol/L. Each of these boluses will be separated by an hour to allow for tissue rehydration without causing unnecessary diuresis from rapid intravascular expansion. A proposed treatment algorithm is shown in Fig. 4. Levels of Cl − ≥ 10 and HCO3−b30 were deemed appropriate to proceed with surgery. Alternatively, practitioners may also use the linear regression model in Figs. 2 and 3 to estimate the fluid requirement to restore electrolytes to the normal range. We feel that administering fluid in the form of a bolus will result in a faster resolution of electrolyte abnormalities. 5. Conclusion Children with electrolyte abnormalities at time of diagnosis of HPS have a longer length of stay; require more fluid resuscitation and more lab draws. We recommend the administration of two 20 ml/kg boluses prior to rechecking labs in patients with initial Cl − value ≤ 97 mmol/L or an initial HCO 3 ≥ 33 mmol/L with a break of 1 h between boluses. Three boluses are recommended if the presenting Cl − b85 or a HCO3 ≥ 40 each separated by an hour.
Fig. 3. IV fluid required for normalization of HCO3−.
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013
4
B.GA. Dalton et al. / Journal of Pediatric Surgery xxx (2016) xxx–xxx
Fig. 4. Fluid resuscitation algorithm based on initial electrolyte values in hypertrophic pyloric stenosis.
While boluses are not being given we would recommend administration of 1.5 times maintenance fluids. If implemented these modifications have potential to save time by not delaying care for extraneous lab results and money in the form of fewer lab draws.
References [1] St Peter SD, Tsao K, Sharp SW, et al. Predictors of emesis and time to goal intake after pyloromyotomy: analysis from a prospective trial. J Pediatr Surg 2008;43(11): 2038–41. http://dx.doi.org/10.1016/j.jpedsurg.2008.04.008.
[2] Adibe OO, Iqbal CW, Sharp SW, et al. Protocol versus ad libitum feeds after laparoscopic pyloromyotomy: a prospective randomized trial. J Pediatr Surg 2014;49(1): 129–32 [discussion 132]. [3] Clayton JT, Reisch JS, Sanchez PJ, et al. Postoperative Regimentation Of Treatment Optimizes Care and Optimizes Length of Stay (PROTOCOL) after pyloromyotomy. J Pediatr Surg 2014 [pii: S0022-3468(14)00859–8]. [4] Graham KA, Laituri CA, Markel TA, et al. A review of postoperative feeding regimens in infantile hypertrophic pyloric stenosis. J Pediatr Surg 2013;48(10):2175–9. http://dx. doi.org/10.1016/j.jpedsurg.2013.04.023 [Review]. [5] Pandya S, Heiss K. Pyloric stenosis in pediatric surgery: an evidence-based review. Surg Clin North Am 2012;92(3):527–39. http://dx.doi.org/10.1016/j.suc.2012.03.006 [vii-viii, Epub 2012 Apr 20. Review]. [6] Wilkinson DJ, Chapman RA, Owen A, et al. Hypertrophic pyloric stenosis: predicting the resolution of biochemical abnormalities. Pediatr Surg Int 2011;27(7):695–8. http://dx.doi.org/10.1007/s00383-010-2813-0.
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013
Contents lists available at ScienceDirect
Journal of Pediatric Surgery journal homepage: www.elsevier.com/locate/jpedsurg
Optimizing fluid resuscitation in hypertrophic pyloric stenosis Brian G.A. Dalton a, Katherine W. Gonzalez a, Sushanth R. Boda a, Priscilla G. Thomas a, Ashley K. Sherman b, Shawn D. St. Peter a,⁎ a b
Department of Pediatric Surgery, Children's Mercy Hospital, Kansas City, MO Department of Research Development and Clinical Investigation, Children's Mercy Hospital, Kansas City, MO
a r t i c l e
i n f o
Article history: Received 5 October 2015 Received in revised form 21 December 2015 Accepted 21 January 2016 Available online xxxx Key words: Hypertrophic pyloric stenosis Electrolyte abnormalities Fluid resuscitation Chloride Bicarbonate Pyloromyotomy
a b s t r a c t Background: Hypertrophic pyloric stenosis (HPS) is the most common diagnosis requiring surgery in infants. Electrolytes are used as a marker of resuscitation for these patients prior to general anesthesia induction. Often multiple fluid boluses and electrolyte panels are needed, delaying operative intervention. We have attempted to predict the amount of IV fluid boluses needed for electrolyte correction based on initial values. Methods: A single center retrospective review of all patients diagnosed with HPS from 2008 through 2014 was performed. Abnormal electrolytes were defined as chloride b100 mmol/L, bicarbonate ≥30 mmol/L or potassium N 5.2 or b3.1 mmol/L. Patients with abnormal electrolytes were resuscitated with 20 ml/kg saline boluses and continuous fluids at 1.5 times maintenance rate. Results: During the study period 542 patients were identified with HPS. Of the 505 who were analyzed 202 patients had electrolyte abnormalities requiring IV fluid resuscitation above maintenance, and 303 patients had normal electrolytes at time of diagnosis. Weight on presentation was significantly lower in the patients with abnormal electrolytes (3.8 vs 4.1 kg, p b 0.01). Length of stay was significantly longer in the patients with electrolyte abnormalities, 2.6 vs 1.9 days (p b 0.01). Fluid given was higher over the entire hospital stay for patients with abnormal electrolytes (106 vs 91 ml/kg/d, p b 0.01). The number of electrolyte panels drawn was significantly higher in patients with initial electrolyte abnormalities, 2.8 vs 1.3 (p b 0.01). Chloride was the most sensitive and specific indicator of the need for multiple saline boluses. Using an ROC curve, parameters of initial Cl− 80 mmol/L and the need for 3 or more boluses AUC was 0.71. Modifying the parameters to initial Cl− ≤97 mmol/L and 2 boluses AUC was 0.65. A patient with an initial Cl− 85 will need three 20 ml/kg boluses 73% (95% CI 52–88%) of the time. A patient with an initial Cl− ≤97 will need two 20 ml/kg boluses at a rate of 73% (95% CI 64–80%). Conclusion: Children with electrolyte abnormalities at time of diagnosis of HPS have a longer length of stay; require more fluid resuscitation and more lab draws. This study reveals high sensitivity and specificity of presenting chloride in determining the need for multiple boluses. We recommend the administration of two 20 ml/kg saline boluses separated by an hour prior to rechecking labs in patients with initial Cl− value ≤97 mmol/L. If the presenting Cl− b 85 three boluses of 20 ml/kg of saline separated by an hour are recommended. If implemented these modifications have potential to save time by not delaying care for extraneous lab results and money in the form of fewer lab draws. © 2016 Elsevier Inc. All rights reserved.
1. Background Hypertrophic pyloric stenosis (HPS) is the most common diagnosis requiring surgery in infants. Electrolytes are used as a marker of resuscitation for these patients prior to general anesthesia induction. Typically, if electrolyte abnormalities (Cl − b 100 mmol/L, HCO3 ≥30 mmol/L, or K + ≤3.4 or ≥5.2 mmol/L) are present on diagnosis of pyloric stenosis, aggressive intravenous fluid resuscitation is given. Often multiple electrolyte panels are needed to assess correction, delaying operative intervention. We have attempted to predict the amount of IV
⁎ Corresponding author at: Children's Mercy Hospital, Department of Surgery, 2401 Gillham Rd., Kansas City, MO 64108. Tel.: +1 816 983 6465; fax: +1 816 983 6885. E-mail address: [email protected] (S.D. St. Peter).
fluid resuscitation needed for electrolyte correction based on initial values. We hypothesized that patients with HPS and abnormal electrolytes would require more than standard fluid resuscitation to correct electrolytes prior to pyloromyotomy, and a review of retrospective data would be able to provide a starting point for a more efficient fluid resuscitation strategy. 2. Methods After approval from the Children's Mercy Hospital Internal Review Board (IRB # 13070217) a single center retrospective chart review was performed. All patients diagnosed with HPS from 2008 through 2014 were considered. Patients were excluded for insufficient data in medical records, or if electrolyte abnormalities were atypical for HPS.
http://dx.doi.org/10.1016/j.jpedsurg.2016.01.013 0022-3468/© 2016 Elsevier Inc. All rights reserved.
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013
2
B.GA. Dalton et al. / Journal of Pediatric Surgery xxx (2016) xxx–xxx
Table 1 Demographic data.
Age (weeks) Gender (%male) Weight (kg) Pylorus length (cm) Pylorus diameter (cm)
Table 2 Initial Cl− and need for saline boluses prior to electrolyte correction. Abnormal electrolytes (n = 202)
Normal electrolytes (n = 303)
p
5.6 83 3.8 2.0 0.4
5.4 84 4.1 2.0 0.4
0.44 0.58 b0.01 0.64 0.19
# of 20 ml/kg boluses
3
2
Data are presented as mean ± standard deviation unless otherwise stated. Significance is defined as p ≤ 0.05. Comparative analysis was performed using Student t test for continuous variables and Fisher exact for binary variables or chi square test with Pearson correlation where appropriate. Area under the curve (AUC) was calculated using receiver operating characteristic (ROC) curve. Abnormal electrolytes were defined as chloride b100 mmol/L, bicarbonate ≥30 mmol/L or potassium N 5.2 or b 3.1 mmol/L. Maintenance fluid given was 5% dextrose in 0.45% saline with or without the addition of potassium dependent on the patient's potassium level and urine output. All patients were administered 1.5× maintenance fluids if abnormal electrolytes or urine output was present (b 1 ml/kg/h). All boluses of fluid were given in the form of normal saline. It is our practice for labs to be drawn 1 h after the conclusion of a fluid bolus. 3. Results During the study period 542 patients were identified with pyloric stenosis. Twenty six were excluded to owing to lack of data in the medical record. Eleven were analyzed separately as the electrolyte abnormalities were atypical for pyloric stenosis. Five-hundred five patients were analyzed. All surgeries were performed laparoscopically. Twohundred two of these patients had electrolyte abnormalities requiring IV fluid resuscitation above maintenance, and 303 patients had normal electrolytes at time of diagnosis. Demographic data for these two groups are shown in Table 1.
Cl− value (mmol/L) b70 (n b80 (n b85 (n b90 (n ≤95 (n ≤97 (n
= = = = = =
5) 11) 26) 49) 106) 132)
Sensitivity (%)
Specificity (%)
p
95% CI
100 90.9 73.1 77 71.7 72.7
74.1 75.9 79 80.5 44.8 52.9
0.001 b0.001 b0.001 b0.001 0.02 b0.001
46–100 57–99 52–88 63–87 62–80 64–80
Weight on presentation was significantly lower in the patients with abnormal electrolytes (Table 1). Total length of stay was significantly longer in the patients with electrolyte abnormalities, 2.6 vs 1.9 days (p b 0.001). Fluid given was higher over the entire hospital stay for patients with abnormal electrolytes (106 vs 91 ml/kg/d, p b 0.001). The number of electrolyte panels drawn was significantly higher in patients with initial electrolyte abnormalities, 2.8 vs 1.3 (p b 0.001). The current cost of basic metabolic panel is $105 at our institution. The total cost for basic metabolic panels in the patients with abnormal electrolytes was $59,388 versus $41,360 for those without electrolyte abnormalities. That difference is $18,000 despite the normal electrolyte group having 101 more patients. Average chloride value for patients with abnormal electrolytes was 93 ± 8.4 mmol/L. Twenty six patients presented with a normal chloride level (≥100 mmol/L) but an abnormal chloride level (≥30 mmol/L). Mean bicarbonate on presentation of patients with abnormal electrolytes was 32.5 ± 5.2 mmol/L. Thirty nine patients presented with normal bicarbonate level (b30 mmol/L) and an abnormal chloride level (b 100 mmol/L). Sixty four percent (130 of 202) of patients with abnormal electrolytes on presentation required multiple 20 ml/kg normal saline boluses. Both chloride (Cl−) and bicarbonate (HCO3) were useful markers in determining the number of 20 ml/kg normal saline boluses a patient would require prior to electrolyte normalization (Cl− ≥100, HCO3−b30, K + ≥ 3.4 b5.2 mmol/L). Using a ROC curve, parameters of initial Cl b 80 mmol/L and the need for 3 or more boluses AUC was 0.71 (Fig. 1). Modifying the parameters to initial Cl ≤97 mmol/L and 2 boluses AUC was 0.65. When initial HCO3 ≤ 33 mmol/L and the need for 2 or more boluses are considered AUC was 0.66. Sensitivity and specificity values correlated to variable values of both Cl− and HCO3 are shown in Tables 2 and 3. As seen in the tables, chloride is the more sensitive and specific electrolyte in the gauging the fluid resuscitation needs of a patient with pyloric stenosis. The total fluid required for correction of electrolytes based on initial chloride and bicarbonate values are shown in Figs. 2 and 3 with a linear regression model. Initial potassium value was not useful in guiding fluid resuscitation. Only 13.5% of patients presented with abnormal potassium not owing to hemolysis, 4.5% had a low value and 9.9% with an abnormally high value. Eleven patients (2.2%) were found to have electrolyte abnormalities atypical for pyloric stenosis. All 11 patients were found to have a low bicarbonate level b22 mmol/L (mean 17.8 ± 1.9). Two patients were found to have an elevated chloride level (N111 mmol/L). Nine patients were found to have a normal chloride level on initial evaluation. Nine of eleven patients did receive at least one bolus of 20 ml/kg normal saline.
Table 3 Initial HCO3 and need saline boluses prior to electrolyte correction. # of 20 ml/kg boluses 3 Fig. 1. ROC curve of the need for 3 or more 20 ml/kg saline boluses to normalize electrolytes if initial Cl− b80 mmol/L.
2
HCO3 value (mmol/L)
Sensitivity (%)
Specificity (%)
p
95% CI
≥45 (n ≥40 (n ≥35 (n ≥33 (n ≥31 (n
83.3 68.4 82 77.1 70.6
72.7 77 41.4 44.5 46.1
0.009 b0.001 0.003 0.002 0.02
36–99 43–86 68–91 66–85 62–78
= = = = =
6) 19) 50) 83) 126)
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013
B.GA. Dalton et al. / Journal of Pediatric Surgery xxx (2016) xxx–xxx
3
Fig. 2. IV fluid required for normalization of Cl−.
4. Discussion Abnormal chloride and bicarbonate on presentation have been previously correlated with longer time to goal feeds, often the limiting step in discharge of a patient after successful pyloromyotomy [1]. Our findings are in agreement with this as patients with electrolyte abnormalities had a significantly longer length of stay than those with normal electrolytes at the time of presentation. Postoperative feeding regimens have been studied well [2–5]. However, there is little evidence to guide the amount of fluid resuscitation needed in pyloric stenosis prior to electrolyte normalization in preparation for pyloromyotomy [5]. There has been evidence to characterize the rate of electrolyte abnormality correction with a particular fluid resuscitation protocol [6]. Our current practice is to administer a bolus of 20 ml/kg normal saline in a patient diagnosed with pyloric stenosis and then recheck electrolytes. When the patient is not receiving a bolus intravenous 5% dextrose in 0.45% saline is with or without potassium administered at a rate of 1.5 times maintenance rate. With the data presented here, we will plan a change in practice. This will include the use of chloride as the most sensitive indicator to guide resuscitation. Our data show that nearly 73% of patients with an initial chloride less than 97 mmol/L will require at least 2 boluses of 20 ml/kg of saline. In this situation we plan to provide 40 ml/kg of saline for initial resuscitation while keeping the
continuous rate at 1.5 times maintenance when the patient is not receiving a bolus. If the chloride is less than 85 mmol/L 60 ml/kg will be administered in the form of 3 boluses. If chloride is normal, but bicarbonate is abnormal then the cutoffs for 40 and 60 ml/kg would be 33 and 40 mmol/L. Each of these boluses will be separated by an hour to allow for tissue rehydration without causing unnecessary diuresis from rapid intravascular expansion. A proposed treatment algorithm is shown in Fig. 4. Levels of Cl − ≥ 10 and HCO3−b30 were deemed appropriate to proceed with surgery. Alternatively, practitioners may also use the linear regression model in Figs. 2 and 3 to estimate the fluid requirement to restore electrolytes to the normal range. We feel that administering fluid in the form of a bolus will result in a faster resolution of electrolyte abnormalities. 5. Conclusion Children with electrolyte abnormalities at time of diagnosis of HPS have a longer length of stay; require more fluid resuscitation and more lab draws. We recommend the administration of two 20 ml/kg boluses prior to rechecking labs in patients with initial Cl − value ≤ 97 mmol/L or an initial HCO 3 ≥ 33 mmol/L with a break of 1 h between boluses. Three boluses are recommended if the presenting Cl − b85 or a HCO3 ≥ 40 each separated by an hour.
Fig. 3. IV fluid required for normalization of HCO3−.
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013
4
B.GA. Dalton et al. / Journal of Pediatric Surgery xxx (2016) xxx–xxx
Fig. 4. Fluid resuscitation algorithm based on initial electrolyte values in hypertrophic pyloric stenosis.
While boluses are not being given we would recommend administration of 1.5 times maintenance fluids. If implemented these modifications have potential to save time by not delaying care for extraneous lab results and money in the form of fewer lab draws.
References [1] St Peter SD, Tsao K, Sharp SW, et al. Predictors of emesis and time to goal intake after pyloromyotomy: analysis from a prospective trial. J Pediatr Surg 2008;43(11): 2038–41. http://dx.doi.org/10.1016/j.jpedsurg.2008.04.008.
[2] Adibe OO, Iqbal CW, Sharp SW, et al. Protocol versus ad libitum feeds after laparoscopic pyloromyotomy: a prospective randomized trial. J Pediatr Surg 2014;49(1): 129–32 [discussion 132]. [3] Clayton JT, Reisch JS, Sanchez PJ, et al. Postoperative Regimentation Of Treatment Optimizes Care and Optimizes Length of Stay (PROTOCOL) after pyloromyotomy. J Pediatr Surg 2014 [pii: S0022-3468(14)00859–8]. [4] Graham KA, Laituri CA, Markel TA, et al. A review of postoperative feeding regimens in infantile hypertrophic pyloric stenosis. J Pediatr Surg 2013;48(10):2175–9. http://dx. doi.org/10.1016/j.jpedsurg.2013.04.023 [Review]. [5] Pandya S, Heiss K. Pyloric stenosis in pediatric surgery: an evidence-based review. Surg Clin North Am 2012;92(3):527–39. http://dx.doi.org/10.1016/j.suc.2012.03.006 [vii-viii, Epub 2012 Apr 20. Review]. [6] Wilkinson DJ, Chapman RA, Owen A, et al. Hypertrophic pyloric stenosis: predicting the resolution of biochemical abnormalities. Pediatr Surg Int 2011;27(7):695–8. http://dx.doi.org/10.1007/s00383-010-2813-0.
Please cite this article as: Dalton BGA, et al, Optimizing fluid resuscitation in hypertrophic pyloric stenosis, J Pediatr Surg (2016), http://dx.doi.org/ 10.1016/j.jpedsurg.2016.01.013