Perioperative apnea in infants with hypertrophic pyloric stenosis: A systematic review

Utility of Pyloric Length Measurement for Detecting Severe Metabolic Alkalosis in Infants with Hypertrophic Pyloric Stenosis

Purpose

Infantile hypertrophic pyloric stenosis (IHPS) is a common gastrointestinal disease in neonates and hypochloremia metabolic alkalosis is a typical laboratory finding in affected patients. This study aimed to analyze the clinical characteristics of infants with IHPS and evaluate the association of clinical and laboratory parameters with ultrasonographic findings.

Methods

Infants diagnosed with IHPS between January 2017 and July 2022 were retrospectively evaluated.

Results

A total of 67 patients were included in the study. The mean age at diagnosis was 40.5±19.59 days, and the mean symptom duration was 11.97±9.91 days. The mean pyloric muscle thickness and pyloric canal length were 4.87±1.05 mm and 19.6±3.46 mm, respectively. Hyponatremia and metabolic alkalosis were observed in five (7.5%) and 36 (53.7%) patients, respectively. Serum sodium (p=0.011), potassium (p=0.023), and chloride levels (p=0.015) were significantly lower in patients with high bicarbonate levels (≥30 mmol/L). Furthermore, pyloric canal length was significantly higher in patients with high bicarbonate levels (p=0.015). To assess metabolic alkalosis in IHPS patients, the area under the receiver operating characteristic curve of pyloric canal length was 0.910 and the optimal cutoff value of the pyloric canal length was 23.5 mm.

Conclusion

We found a close association between laboratory and ultrasonographic findings of IHPS. Clinicians should give special consideration to patients with pyloric lengths exceeding 23.5 mm and appropriate fluid rehydration should be given to these patients.

Perioperative Hypoxemia and Postoperative Respiratory Events in Infants with Hypertrophic Pyloric Stenosis

BACKGROUND

 Normalization of metabolic alkalosis is an important pillar in the treatment of infantile hypertrophic pyloric stenosis (IHPS) because uncorrected metabolic alkalosis may lead to perioperative respiratory events. However, the evidence on the incidence of respiratory events is limited. We aimed to study the incidence of peroperative hypoxemia and postoperative respiratory events in infants undergoing pyloromyotomy and the potential role of metabolic alkalosis.

MATERIALS AND METHODS

 We retrospectively reviewed all patients undergoing pyloromyotomy between 2007 and 2017. All infants received intravenous fluids preoperatively to correct metabolic abnormalities close to normal. We assessed the incidence of perioperative hypoxemia (defined as oxygen saturation [SpO2] < 90% for > 1min) and postoperative respiratory events. Additionally, the incidence of difficult intubations was evaluated. We performed a multivariate logistic regression analysis to evaluate the association between admission or preoperative serum pH values, bicarbonate or chloride, and peri- and postoperative hypoxemia or respiratory events.

RESULTS

 Of 406 included infants, 208 (51%) developed 1 or more episodes of hypoxemia during the perioperative period, of whom 130 (32%) experienced it during induction, 43 (11%) intraoperatively, and 112 (28%) during emergence. About 7.5% of the infants had a difficult intubation and 17 required more than 3 attempts by a pediatric anesthesiologist. Three patients developed respiratory insufficiency and 95 postoperative respiratory events were noticed. We did not find a clinically meaningful association between laboratory values reflecting metabolic alkalosis and respiratory events.

CONCLUSIONS

 IHPS frequently leads to peri- and postoperative hypoxemia or respiratory events and high incidence of difficult tracheal intubations. Preoperative pH, bicarbonate, and chloride were bad predictors of respiratory events.

Evaluation of a fluid resuscitation protocol for patients with hypertrophic pyloric stenosis

INTRODUCTION

We previously developed an institutional, evidence-based fluid resuscitation protocol for neonates with infantile hypertrophic pyloric stenosis (HPS) based on the severity of electrolyte derangement on presentation. We aim to evaluate this protocol to determine its efficacy in reducing the number of preoperative lab draws, time to electrolyte correction, and overall length of stay.

METHODS

A single center, retrospective review of 319 infants with HPS presenting with electrolyte derangement from 2008 to 2020 was performed; 202 patients managed pre-protocol (2008-2014) and 117 patients managed per our institutional fluid resuscitation algorithm (2016-2020). The number of preoperative lab draws, time to electrolyte correction, and length of stay before and after protocol implementation was recorded.

RESULTS

Use of a fluid resuscitation algorithm decreased the number of infants who required four or more preoperative lab draws (20% vs. 6%) (p < .01), decreased median time to electrolyte correction between the pre and post protocol cohorts (15.1 h [10.6, 22.3] vs. 11.9 h [8.5, 17.9]) (p < .01), and decreased total length of hospital stay (49.0 h [40.3, 70.7] vs. 45.7 h [34.3, 65.9]) (p < .05).

CONCLUSION

Implementation of a fluid resuscitation algorithm for patients presenting with hypertrophic pyloric stenosis decreases the frequency of preoperative lab draws, time to electrolyte correction, and total length of hospital stay. Use of a fluid resuscitation protocol may decrease discomfort through fewer preoperative lab draws and shorter length of stay while setting clear expectations and planned intervention for parents.

LEVEL OF EVIDENCE

III - Retrospective comparative study.

Postoperative apnea after pyloromyotomy for infantile hypertrophic pyloric stenosis

Objective

Infantile hypertrophic pyloric stenosis (IHPS), which causes gastric outlet obstruction and hypochloremic hypokalemic metabolic alkalosis, could pose a risk of postoperative apnea in patients. The aim of this study is to evaluate the incidence of postoperative apnea in babies admitted to a tertiary-level pediatric surgical center in Milano, Italy with diagnosis of IHPS in 2010–2019. The secondary objective is to evaluate the risk factors for postoperative apnea.

Methods

This is a single-center, retrospective, observational cohort study. All patients admitted to our institution with diagnosis of IHPS during the study period were enrolled. Demographic and surgical variables, along with blood gas parameters, were obtained from the population. Postoperative apnea was defined as a respiratory pause longer than 15 s or a respiratory pause lasting less than 15 s, but associated with either bradycardia (heart rate <120 per minute), desaturation (SatO2 <90%), cyanosis, or hypotonia. Occurrence was obtained from nursing charts and was recorded as a no/yes dichotomous variable.

Results

Of 122 patients, 12 (9.84%) experienced apnea and 110 (90.16%) did not. Using univariate analysis, we found that only postoperative hemoglobin was significantly different between the groups (p=0.03). No significant multivariable model was better than this univariate model for prediction of apnea.

Conclusions

Postoperative anemia, possibly due to hemodilution, increased the risk of postoperative apnea. It could be hypothesized that anemia can be added as another apnea-contributing factor in a population at risk due to metabolic changes.

Perioperative apnea in infants with hypertrophic pyloric stenosis: A systematic review

BACKGROUND

Infantile hypertrophic pyloric stenosis (IHPS) leads to excessive vomiting and metabolic alkalosis, which may subsequently cause apnea. Although it is generally assumed that metabolic derangements should be corrected prior to surgery to prevent apnea, the exact incidence of perioperative apneas in infants with IHPS and the association with metabolic alkalosis are unknown. We performed this systematic review to assess the incidence of apnea in infants with IHPS and to verify the possible association between apnea and metabolic alkalosis.

METHODS

We searched MEDLINE, Embase, and Cochrane library to identify studies regarding infants with metabolic alkalosis, respiratory problems, and hypertrophic pyloric stenosis. We conducted a descriptive synthesis of the findings of the included studies.

RESULTS

Thirteen studies were included for analysis. Six studies described preoperative apnea, three studies described postoperative apnea, and four studies described both. All studies were of low quality or had other research questions. We found an incidence of 27% of preoperative and 0.2%-16% of postoperative apnea, respectively. None of the studies examined the association between apnea and metabolic alkalosis in infants with IHPS.

CONCLUSIONS

Infants with IHPS may have a risk to develop perioperative apnea. However, the incidence rates should be interpreted with caution because of the low quality and quantity of the studies. Therefore, further studies are required to determine the incidence of perioperative apnea in infants with IHPS. The precise underlying mechanism of apnea in these infants is still unknown, and the role of metabolic alkalosis should be further evaluated.