Incidence and risk factors for preincision hypotension in a noncardiac pediatric surgical population

[Intraoperative hypotension in children-Measurement and treatment]

Intraoperative hypotension is a common perioperative complication in pediatric anesthesia. Oscillometric blood pressure measurement is therefore an essential part of standard perioperative monitoring in pediatric anesthesia. The optimum measurement site is the upper arm. Attention must be paid to the correct cuff size. Blood pressure should be measured before induction. In children undergoing major surgery or in critically ill children, invasive blood pressure measurement is still the gold standard. Continuous noninvasive measurement methods could be an alternative in the future.Threshold values to define hypotension remain unknown, even in awake children. There are also little data on hypotension thresholds in the perioperative setting. The most reliable measurement parameter for estimating hypotension is the mean arterial pressure. The threshold values for intraoperative hypotension are 40 mm Hg in newborns, 45 mm Hg in infants, 50 mm Hg in young children and 65 mm Hg in adolescents. Treatment should be initiated at a deviation of 10% and intensified at a deviation of 20%.Bolus administration of isotonic balanced crystalloid solutions, vasopressors and/or catecholamines are used as treatment options. Consistent and rapid intervention in the event of hypotension appears to be crucial. So far there is no evidence as to whether this leads to an improvement in outcome parameters.

A Retrospective Comparative Study of the Frequency of Hypotension in Pediatric Cardiac Catheterization under General Anesthesia: Remimazolam versus Sevoflurane

OBJECTIVE

To compare the incidence of hypotension between remimazolam and sevoflurane under general anesthesia for cardiac catheterization in patients with congenital heart disease.

DESIGN

Retrospective observational study.

SETTING

A single university hospital with 300 pediatric cardiac catheterizations by general anesthesia performed annually.

PARTICIPANTS

Patients younger than 15 years who underwent cardiac catheterization under general anesthesia between March 1, 2021, and December 31, 2022. Exclusion criteria were general anesthesia maintained with other than remimazolam or sevoflurane, receipt of remifentanil, American Society of Anesthesiologists score 4 or 5, emergency procedures, and no direct arterial pressure measurement.

INTERVENTIONS

General anesthesia was maintained with remimazolam or sevoflurane.

MEASUREMENTS AND MAIN RESULTS

A total of 309 patients were analyzed, including 28 in the remimazolam group and 281 in the sevoflurane group. Propensity score matching adjusted for confounding factors resulted in 28 patients in each arm, with no apparent differences in background factors. Hypotension was defined as a time-averaged area > 1, in which systolic arterial pressure fell below 80% of the baseline from the start of anesthesia to the end of procedure. The significance level was set at P < .05. The incidence of hypotension was 39.3% in the remimazolam arm and 46.4% in the sevoflurane arm, with no significant difference (P = .79), although the ratio of the median systolic arterial pressure to the baseline value was significantly higher in the remimazolam arm (91.4 ± 15.2% vs 83.2 ± 11.4% in the sevoflurane arm; P = .03).

CONCLUSIONS

Remimazolam was not associated with a lower incidence of hypotension compared to sevoflurane during pediatric cardiac catheterization for congenital heart disease while maintaining significantly higher blood pressure overall.

Sedation and anesthesia for imaging of the infant and neonate-a brief review

Sedation and anesthesia are often required in order to facilitate collection of high-quality imaging studies free of significant motion artifact for infants and neonates. Provision of safe sedation and anesthesia requires good communication between the ordering provider, radiologist, and anesthesiologist, careful pre-procedural evaluation of the patient, and availability of appropriate and sufficient equipment, drugs, personnel, and facilities. There are many additional factors to be considered for provision of safe sedation or anesthesia for infants and neonates-it is ideal to involve a fellowship-trained pediatric anesthesiologist in the planning and carry-out of these plans. In this review, we discuss some of the basic definitions of sedation and anesthesia, requirements for safe sedation and anesthesia, and many of the germane risks and additional considerations that factor into the delivery of a safe sedation or anesthesia plan for the imaging of an infant or neonate.

Association of infraclavicular axillary vein diameter and collapsibility index with general anesthesia-induced hypotension in elderly patients undergoing gastrointestinal surgery: an observational study

BACKGROUND

The collapse index of inferior Vena Cava (IVC) and its diameter are important predictive tools for fluid responsiveness in patients, especially critically ones. The collapsibility of infraclavicular axillary vein (AXV) can be used as an alternative to the collapsibility of IVC (IVC-CI) to assess the patient's blood volume.

METHODS

A total of 188 elderly patients aged between 65 and 85 years were recruited for gastrointestinal surgery under general anesthesia. Ultrasound measurements AXV and IVC were performed before induction of general anesthesia. Patients were grouped in accordance to the hypotension after induction. ROC curves were used to analyze the predictive value of ultrasound measurements of AXV and IVC for hypotension after induction of anesthesia. Pearson linear correlation was used to assess the correlation of ultrasound measurements and decrease in mean arterial blood pressure (MAP).

RESULTS

The maximum diameter of AXV(dAXVmax) and the maximum diameter of IVC (dIVCmax) were not related to the percentage decrease in MAP; the collapsibility of AXV (AXV-CI) and IVC-CI were positively correlated with MAP changes (correlation coefficients:0.475, 0.577, respectively, p < 0.001). The areas under the curve (AUC) was 0.824 (0.759-0.889) for AXV-CI, and 0.874 (0.820-0.928) for IVC-CI. The optimal threshold for AXV-CI was 31.25% (sensitivity 71.7%, specificity 90.1%), while for IVC-CI was 36.60% (sensitivity 85.9%, specificity 79.0%). Hypotension and down-regulation of MAP during induction can be accurately predicted by AXV-Cl after correction for confounding variables.

CONCLUSION

Infraclavicular axillary vein diameter has no significant correlation with postanesthesia hypotension, whereas AXV-CI may predict postanesthesia hypotension during gastrointestinal surgery of the elderly.

TRIAL REGISTRATION

This study was registered in the Clinical Trial Registry of China on 05/06/2022 (ChiCTR2200060596).

Prediction of fluid responsiveness using lung recruitment manoeuvre in paediatric patients receiving lung-protective ventilation: A prospective observational study

BACKGROUND

Pressure-based dynamic variables are poor predictors of fluid responsiveness in children, and their predictability is expected to reduce further during lung-protective ventilation with a low tidal volume.

OBJECTIVE

We hypothesised that lung recruitment manoeuvre (LRM)-induced changes in dynamic variables improve their ability to predict fluid responsiveness in children.

DESIGN

Prospective observational study.

SETTING

Tertiary care children's hospital, single-centre study performed from June 2017 to May 2019.

PATIENTS

We included patients less than 7 years of age undergoing cardiac surgery. Neonates and patients with pulmonary hypertension, significant dysrhythmia, ventricular ejection fraction of less than 30% or pulmonary disease were excluded.

INTERVENTION

All patients were provided with lung-protective volume-controlled ventilation (tidal volume 6 ml kg-1, positive end-expiratory pressure 6 cmH2O). A LRM was applied with a continuous inspiratory pressure of 25 cmH2O for 20 s.

MAIN OUTCOME MEASURE

The ability of dynamic variables to predict fluid responsiveness was evaluated by the area under the receiver operating characteristic curve [area under the curve (AUC)]. Fluid responsiveness was defined as an increase in the cardiac index by more than 15% with crystalloid administration (10 ml kg-1).

RESULTS

Thirty patients were included in the final analysis, of whom 19 were responders. The baseline pleth variability index (PVI) (AUC 0.794, 95% confidence interval 0.608 to 0.919, P < 0.001) and LRM-induced PVI (AUC 0.711, 95% confidence interval 0.517 to 0.861, P = 0.026) could predict fluid responsiveness. The respiratory variation of pulse oximetry photoplethysmographic waveform and pulse pressure variation did not predict fluid responsiveness regardless of the LRM.

CONCLUSION

The PVI is effective in predicting fluid responsiveness in paediatric patients with lung-protective ventilation regardless of a LRM. However, the LRM did not improve the ability of the other dynamic variables to predict fluid responsiveness in these patients.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier: NCT03184961.

Blood pressure in Danish children during general anaesthesia: Hypotension in a paediatric population observational (HIPPO) study

BACKGROUND

In Denmark, thousands of infants and children require general anaesthesia annually. Hypotension during general anaesthesia might reduce cerebral blood flow and oxygen delivery to the brain. Safe lower limits of blood pressure are ill defined. The Hypotension in Paediatric Populations Observational study objective was to assess blood pressure in Danish children during general anaesthesia.

METHODS

This study is a prospective observational multicentre study. Primary outcomes were mean arterial blood pressures in children aged 0-12 years. Lowest mean arterial blood pressure, intervention thresholds to increase blood pressure and type of intervention were secondary outcomes. Premature infants and children scheduled for cardio-thoracic surgery were excluded. Blood pressures were measured by oscillometry or invasively.

RESULTS

In total, 726 patients were included. In children < 1 year, median arterial pressure was 51 mm Hg, (interquartile range; 43-58) and increased to 58 mm Hg (interquartile range; 52-65) for 12-year-old children. In 32 patients, 49 actions were taken to modulate blood pressure. Pre-induction blood pressures were recorded for 29%.

CONCLUSION

This study presents pragmatic, multicentre, prospectively collected observations of blood pressure in children undergoing general anaesthesia in usual practice. In the youngest infants, variability in blood pressure appears to be large. Measurement of blood pressure is recommended during every general anaesthesia and in children of all ages. Safe ranges of blood pressure remain to be defined.

Hormonal Blood Pressure Regulationduring General Anesthesia Usinga Standardized Propofol Dosagein Children and Adolescents SeemsNot to Be Affected by Body Weight

Obesity in pediatric surgical patients is a challenge for the anesthesiologist. Despite potentially beneficial properties, propofol might also induce hypotension. This study examined whether a dose adjustment in overweight children could avoid hypotension and if there would be differences regarding hormonal regulation in children under anesthesia. Fifty-nine children undergoing surgery under general anesthesia were enrolled in this prospective observational trial. Participants were allocated into two groups according to their BMI. The induction of anesthesia was conducted using propofol (“overweight”: 2 mg/kgBW, “regular”: 3.2 mg/kgBW). The maintenance of anesthesia was conducted as total intravenous anesthesia. Hormone levels of renin, angiotensin II, aldosterone, copeptin, norepinephrine and epinephrine were assessed at different timepoints. Blood pressure dropped after the administration of propofol in both groups, with a nadir 2 min after administration—but without a significant difference in the strength of reduction between the two groups. As a reaction, an increase in the plasma levels of renin, angiotensin and aldosterone was observed, while levels of epinephrine, norepinephrine and copeptin dropped. By adjusting the propofol dosage in overweight children, the rate of preincision hypotension could be reduced to the level of normal-weight patients with a non-modified propofol dose. The hormonal counter regulation was comparable in both groups. The release of catecholamines and copeptin as an indicator of arginine vasopressin seemed to be inhibited by propofol.

Preoperative Fluid Fasting Times and Postinduction Low Blood Pressure in Children

Background

Children are required to fast before elective general anesthesia. This study hypothesized that prolonged fasting causes volume depletion that manifests as low blood pressure. This study aimed to assess the association between fluid fasting duration and postinduction low blood pressure.

Methods

A retrospective cohort study was performed of 15,543 anesthetized children without preinduction venous access who underwent elective surgery from 2016 to 2017 at Children’s Hospital of Philadelphia. Low blood pressure was defined as systolic blood pressure lower than 2 standard deviations below the mean (approximately the 2.5th percentile) for sex- and age-specific reference values. Two epochs were assessed: epoch 1 was from induction to completion of anesthesia preparation, and epoch 2 was during surgical preparation.

Results

In epoch 1, the incidence of low systolic blood pressure was 5.2% (697 of 13,497), and no association was observed with the fluid fasting time groups: less than 4 h (4.6%, 141 of 3,081), 4 to 8 h (6.0%, 219 of 3,652), 8 to 12 h (4.9%, 124 of 2,526), and more than 12 h (5.0%, 213 of 4,238). In epoch 2, the incidence of low systolic blood pressure was 6.9% (889 of 12,917) and varied across the fasting groups: less than 4 h (5.6%, 162 of 2,918), 4 to 8 h (8.1%, 285 of 3,531), 8 to 12 h (5.9%, 143 of 2,423), and more than 12 h (7.4%, 299 of 4,045); after adjusting for confounders, fasting 4 to 8 h (adjusted odds ratio, 1.33; 95% CI, 1.07 to 1.64; P = 0.009) and greater than 12 h (adjusted odds ratio, 1.28; 95% CI, 1.04 to 1.57; P = 0.018) were associated with significantly higher odds of low systolic blood pressure compared with the group who fasted less than 4 h, whereas the increased odds of low systolic blood pressure associated with fasting 8 to 12 h (adjusted odds ratio, 1.11; 95% CI, 0.87 to 1.42; P = 0.391) was nonsignificant.

Conclusions

Longer durations of clear fluid fasting in anesthetized children were associated with increased risk of postinduction low blood pressure during surgical preparation, although this association appeared nonlinear.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Beyond Anesthesia Toxicity: Anesthetic Considerations to Lessen the Risk of Neonatal Neurological Injury

Infants who undergo surgical procedures in the first few months of life are at a higher risk of death or subsequent neurodevelopmental abnormalities. Although the pathogenesis of these outcomes is multifactorial, an understanding of the nature and pathogenesis of brain injury in these infants may assist the anesthesiologist in consideration of their day-to-day practice to minimize such risks. This review will summarize the main types of brain injury in preterm and term infants and their key pathways. In addition, the review will address key potential pathogenic pathways that may be modifiable including intraoperative hypotension, hypocapnia, hyperoxia or hypoxia, hypoglycemia, and hyperthermia. Each of these conditions may increase the risk of perioperative neurological injury, but their long-term ramifications are unclear.

Patient and anesthesia characteristics of children with low pre-incision blood pressure: A retrospective observational study

BACKGROUND

Intraoperative blood pressure has been suggested as a key factor for safe pediatric anesthesia. However, there is not much insight into factors that discriminate between children with low and normal pre-incision blood pressure. Our aim was to explore whether children who have a low blood pressure during anesthesia are different than those with normal blood pressure. The focus of the present study was on the pre-incision period.

METHODS

This retrospective study included pediatric patients undergoing anesthesia for non-cardiac surgery at a tertiary pediatric university hospital, between 2012 and 2016. We analyzed the association between pre-incision blood pressure and patient- and anesthesia characteristics, comparing low with normal pre-incision blood pressure. This association was further explored with a multivariable linear regression.

RESULTS

In total, 20 962 anesthetic cases were included. Pre-incision blood pressure was associated with age (beta -0.04 SD per year), gender (female -0.11), previous surgery (-0.15), preoperative blood pressure (+0.01 per mm Hg), epilepsy (0.12), bronchial hyperactivity (-0.18), emergency surgery (0.10), loco-regional technique (-0.48), artificial airway device (supraglottic airway device instead of tube 0.07), and sevoflurane concentration (0.03 per sevoflurane %).

CONCLUSIONS

Children with low pre-incision blood pressure do not differ on clinically relevant factors from children with normal blood pressure. Although the present explorative study shows that pre-incision blood pressure is partly dependent on patient characteristics and partly dependent on anesthetic technique, other unmeasured variables might play a more important role.

Risk factors for post-induction hypotension in children presenting for surgery

BACKGROUND

Preoperative factors have been correlated with pre-incision hypotension (PIH) in children undergoing surgery, suggesting that PIH can be predicted through preoperative screening. We studied blood pressure (BP) changes in the 12 min following the induction of anesthesia to study the incidence of post-induction hypotension and to assess the feasibility of predicting PIH in low-risk children without preoperative hypotension or comorbid features.

METHODS

We retrospectively evaluated 200 patients ranging in age from 2 to 8 years with American Society of Anesthesiologists' (ASA) physical status I or II, undergoing non-cardiac surgery. Patients were excluded if they had preoperative (baseline) hypotension (systolic blood pressure (SBP) < 5th percentile for age). BP and heart rate (HR) were recorded at 3 min intervals for 12 min after the induction of anesthesia. Pre-incision hypotension (PIH) was initially defined as SBP < 5th percentile for age: (1) at any timepoint within 12 min of induction; (2) for the median SBP obtained during the 12 min study period; or (3) at 2 or more timepoints including the final point at 12 min after the induction of anesthesia (sustained hypotension). In addition, we examined PIH defined as > 20% decrease in SBP from baseline: (4) at any timepoint within 12 min of the induction of anesthesia; (5) for the median SBP obtained during the 12 min study period; or (6) at two or more timepoints including the final point at 12 min after the induction of anesthesia. Agreement among the six definitions was analyzed, in addition to the effects of age, gender, type of anesthetic induction, use of premedication, preoperative BP, preoperative HR, and body mass index on the incidence of PIH according to each definition.

RESULTS

Five patients were excluded due to baseline hypotension and six were excluded for missing data. In the remaining cohort, estimated PIH prevalence ranged from 4% [definition (Stewart et al., in Paediatr Anaesth 26:844-851, 2016), sustained PIH according to SBP percentile-for-age] to 57% [definition (Task Force on Blood Pressure Control in Children, in Pediatrics 79:1-25, 1987), at least one timepoint where SBP was > 20% lower than baseline]. Pairwise agreement among the six definitions ranged from 49 to 91% agreement. No sequelae of PIH were noted during subsequent anesthetic or postoperative care. On multivariable analysis, no covariates were consistently associated with PIH risk across all six definitions of PIH.

CONCLUSION

The present study describes the incidence and prediction of PIH in a cohort of relatively healthy children. In this setting, accurate prediction of PIH appears to be hampered by lack of agreement between definitions of PIH. Overall, there was a low PIH incidence when the threshold of SBP < 5th percentile for age was used.

LEVEL OF EVIDENCE

II.

Effects of moderate and severe arterial hypotension on intracerebral perfusion and brain tissue oxygenation in piglets

BACKGROUND

Hypotension is common in anaesthetised children, and its impact on cerebral oxygenation is unknown. The goal of the present study was to investigate the effects of moderate systemic arterial hypotension (mHT) and severe hypotension (sHT) on cerebral perfusion and brain tissue oxygenation in piglets.

METHODS

Twenty-seven anaesthetised piglets were randomly allocated to a control group, mHT group, or sHT group. Cerebral monitoring comprised a tissue oxygen partial pressure ( [Formula: see text] ) and laser Doppler (LD) perfusion probe advanced into the brain tissue, and a near-infrared spectroscopy sensor placed over the skin measuring regional oxygen saturation (rSO₂). Arterial hypotension was induced by blood withdrawal and i.v. nitroprusside infusion [target MAP: 35-38 (mHT) and 27-30 (sHT) mm Hg]. Data were analysed at baseline, and every 20 min during and after treatment.

RESULTS

Compared with control, [Formula: see text] decreased equally with mHT and sHT [mean (SD) after 60 min: control: 17.1 (6.4); mHT: 6.4 (3.6); sHT: 7.2 (4.3) mm Hg]. No differences between groups were detected for rSO₂ and LD during treatment. However, in the sHT group, rSO₂ increased after restoring normotension [from 49.3 (9.5) to 58.9 (8.9)% Post60]. sHT was associated with an increase in blood lactate [from 1.5 (0.4) to 2.4 (0.9) mmol L^-1], and a decrease in bicarbonate [28 (2.4) to 25.8 (2.6) mmol L^-1] and base excess [4.7 (1.9) to 2.0 (2.7) mmol L^-1] between baseline and 60 min after the start of the experiment.

CONCLUSIONS

Induction of mHT and sHT by hypovolaemia and nitroprusside infusion caused alterations in brain tissue oxygenation in a piglet model, but without detectable changes in brain tissue perfusion and regional oxygen saturation.

The timing and prevalence of intraoperative hypotension in infants undergoing laparoscopic pyloromyotomy at a tertiary pediatric hospital

BACKGROUND

Intraoperative hypotension may be associated with adverse outcomes in children undergoing surgery. Infants and neonates under 6 months of age have less autoregulatory cerebral reserve than older infants, yet little information exists regarding when and how often intraoperative hypotension occurs in infants.

AIMS

To better understand the epidemiology of intraoperative hypotension in infants, we aimed to determine the prevalence of intraoperative hypotension in a generally uniform population of infants undergoing laparoscopic pyloromyotomy.

METHODS

Vital sign data from electronic records of infants who underwent laparoscopic pyloromyotomy with general anesthesia at a children's hospital between January 1, 1998 and October 4, 2013 were analyzed. Baseline blood pressure (BP) values and intraoperative BPs were identified during eight perioperative stages based on anesthesia event timestamps. We determined the occurrence of relative (systolic BP <20% below baseline) and absolute (mean arterial BP <35 mmHg) intraoperative hypotension within each stage.

RESULTS

A total of 735 full-term infants and 82 preterm infants met the study criteria. Relative intraoperative hypotension occurred in 77%, 72%, and 58% of infants in the 1-30, 31-60, and 61-90 days age groups, respectively. Absolute intraoperative hypotension was seen in 21%, 12%, and 4% of infants in the 1-30, 31-60, and 61-90 days age groups, respectively. Intraoperative hypotension occurred primarily during surgical prep and throughout the surgical procedure. Preterm infants had higher rates of absolute intraoperative hypotension than full-term infants.

CONCLUSIONS

Relative intraoperative hypotension was routine and absolute intraoperative hypotension was common in neonates and infants under 91 days of age. Preterm infants and infants under 61 days of age experienced the highest rates of absolute and relative intraoperative hypotension, particularly during surgical prep and throughout surgery.

The association between pre-operative variables, including blood pressure, and postoperative kidney function

We used multivariate analyses to assess the association of pre-operative variables with kidney function in 41,523 adults after scheduled surgery in a single large academic hospital. Eight variables were independently associated with a reduction in postoperative estimated glomerular filtration rate: pre-operative renal function; age; ASA physical status; cardiac failure; anaemia; cancer; type of surgery; and the lowest quartile of pre-operative mean arterial blood pressure (< 71 mmHg). The estimated glomerular filtration rate fell by a mean (95% CI) of 2.7 (0.04-5.40) ml.min^-1 .1.73 m^-2 for patients with a pre-operative mean arterial pressure < 71 mmHg, p = 0.047. The same variables and male sex were associated with postoperative acute kidney injury. The odds ratio (95% CI) for acute postoperative kidney injury was 1.9 (1.2-2.9) for patients with a pre-operative mean arterial blood pressure < 71 mmHg, p = 0.005.

Effects of hypotension and/or hypocapnia during sevoflurane anesthesia on perfusion and metabolites in the developing brain of piglets-a blinded randomized study

BACKGROUND

Hypotension (HT) and/or hypocapnia (HC) are frequent complications occurring during pediatric anesthesia and may cause cerebral injury in the developing brain.

AIM

The aim of this study is to investigate the effects of HT and/or HC on perfusion and metabolism in the developing brain.

METHODS

Twenty-eight piglets were randomly allocated to four groups: control (C), HT, HC, and hypotension and hyocapnia (HTC). Anesthesia was induced and maintained using sevoflurane. Fentanyl was added for instrumentation. Piglets were fully monitored and their lungs were artificially ventilated. Before treatment, conventional magnetic resonance imaging (MRI), dynamic susceptibility-contrast-enhanced T2*-weighted MRI (DSC-MRI), and single voxel proton MR spectroscopy ((1) H MRS) were performed. Hypotension (mean arterial blood pressure: 30 ± 3 mmHg) was induced by blood withdrawal and nitroprusside infusion, and hyperventilation was used to induce HC (PaCO2 : 2.7-3.3 kPa). (1) H MRS and DSC-MRI were repeated immediately once treatment goals were achieved and 120 min later. Radiologists were blinded to the groups. DSCI-MRI and (1) H MRS analyses were performed in the thalamus, occipital and parietal lobe, hippocampus, and watershed areas.

RESULTS

In comparison to C, mean time to peak (TTP) increased with HTC in all brain areas as assessed with DSC-MRI (n = 26). Using (1) H MRS, a significant decrease in N-acetyl aspartate, choline, and myoinositol, as well as an increase in glutamine-glutamate complex (Glx) were detected independent of group. Compared to C, changes were more pronounced for Glx (due to an increase in glutamate) and myoinositol with HTC, for N-acetyl aspartate with HT, and for Glx with HC. No lactate signal was present.

CONCLUSIONS

The combination of HT and HC during sevoflurane anesthesia resulted in alteration of cerebral perfusion with signs of neuronal dysfunction and early neuronal ischemia. HT and HC alone also resulted in signs of metabolic disturbances despite the absence of detectable cerebral perfusion alterations.

Association of elevated preoperative blood pressure with preincision hypotension in pediatric surgical patients

INTRODUCTION

High blood pressure (BP) in childhood is associated with left ventricular hypertrophy and abnormal vascular reactivity even in apparently healthy children. This study examined the prevalence of high BP in children undergoing elective noncardiac operations. We also determined the association of preoperative high BP with preincision hypotension (PIH).

METHODS

This was a retrospective cohort study that used clinical and anthropometric data on children aged 3-17 years who underwent elective, noncardiac operations from January 2006 to January 2014. Preoperative blood pressure (BP) was used to stratify children into three categories: normal BP (systolic and diastolic BP below the 90th percentile), prehypertension (systolic and/or diastolic BP ≥90th percentile but <95th percentile or if the BP exceeds 120/80 mmHg even if it is below the 90th percentile), and hypertension (systolic and/or diastolic BP ≥95th percentile). Multivariable logistic regression analysis was used to calculate adjusted odds ratios for PIH using age, gender, body mass index (BMI), and BP categories as covariates.

RESULTS

Among 35832 children, the overall prevalence of prehypertension, hypertension, and hypertension by adult standards were 16.4%, 6.8%, and 3.3%, respectively. Overweight and obese children had higher rates of elevated BP. Presence of elevated baseline BP, high BMI category, and presence of OSA diagnosis were independent predictors of multiple episodes of PIH in a logistic regression model.

CONCLUSION

In children, preoperative high BP is an independent predictor of PIH. Although the longtime consequences of high BP are well known, this report provides the first intraoperative evidence of adverse event associated with preoperative high BP in children. Mechanisms underlying this hypotensive response are unclear.

Arterial blood pressure in anesthetized neonates and infants: a retrospective analysis of 1091 cases

BACKGROUND

Hypotension during general anesthesia in neonates and infants is considered to contribute to poor neurological outcome.

AIM

The aim of this retrospective analysis was to determine the incidence of hypotension after induction of anesthesia and sustained hypotension (>10 min) during the anesthesia, and to determine factors contributing to the development of (sustained) hypotension.

METHOD

We performed a retrospective analysis of 1091 electronic anesthesia records from children <1 year. Patients were stratified for age (group 1: <1 month, group 2: 1-3 months, group 3: 4-6 months, group 4: >6 months). Hypotension was defined as a mean arterial pressure (MAP) <35 mmHg in patients ≤6 months and <43 mmHg in patients >6 months.

RESULTS

The incidence of hypotension after induction was highest in group 1 (25.5%) [P = 0.009 vs group 2 (13.3%), P < 0.0001 vs groups 3 (3.4%) and 4 (1.0%)], in group 2, it was higher than in groups 3 and 4 (P < 0.0001), and in group 3, it was higher than in group 4 (P = 0.033). The incidence of sustained hypotension was highest in group 1 (43.6%) (P < 0.0001 vs groups 2-4), followed by group 2 (15.7%) [P < 0.0001 vs group 3 (3.4%) and P = 0.006 vs group 4 (8.8%)] and group 4 (P = 0.004 vs group 3). Hypotension after induction occurred more often in emergency procedures than in elective procedures in groups 1 (P = 0.002), 2 (P = 0.029), and 3 (P = 0.037).

CONCLUSION

Hypotension, both postinduction and sustained during surgery, is a common phenomenon in anesthetized children under 1 year, peaking in neonates. Generally accepted lower limits of MAP in anesthetized infants urgently need to be defined, enabling us to develop anesthesia strategies avoiding cerebral hypoperfusion.

Controversies in Pediatric Perioperative Airways

Pediatric airway management is a challenge in routine anesthesia practice. Any airway-related complication due to improper procedure can have catastrophic consequences in pediatric patients. The authors reviewed the current relevant literature using the following data bases: Google Scholar, PubMed, Medline (OVID SP), and Dynamed, and the following keywords: Airway/s, Children, Pediatric, Difficult Airways, and Controversies. From a summary of the data, we identified several controversies: difficult airway prediction, difficult airway management, cuffed versus uncuffed endotracheal tubes for securing pediatric airways, rapid sequence induction (RSI), laryngeal mask versus endotracheal tube, and extubation timing. The data show that pediatric anesthesia practice in perioperative airway management is currently lacking the strong evidence-based medicine (EBM) data that is available for adult subpopulations. A number of procedural steps in airway management are derived only from adult populations. However, the objective is the same irrespective of patient age: proper securing of the airway and oxygenation of the patient.

The association of hypotension with the insertion of an abdominal retractor during lower abdominal surgery in pediatric patients: a retrospective observational study

BACKGROUND

The Alexis(®) wound retractor is composed of an inner- and outer-ring, with the inner-ring placed inside the abdominal cavity. This placement can constrict the internal organs and large vessels, especially in children, which can lead to hypotension. Our study aimed to investigate the relation between the incidence of hypotension and insertion of the wound retractor during lower abdominal surgery in pediatric patients.

METHODS

We retrospectively examined 161 pediatric patients (<4 years old), who underwent lower abdominal surgery, regardless of abdominal retractor type. Hypotension was defined as a decrease in systolic blood pressure of >15% from baseline. We used logistic regression to predict hypotension using the following nine parameters: age, height, weight, American Society of Anesthesiologists physical status (ASA-PS), sex, laterality of the operation (unilateral or bilateral), presence or absence of caudal block, wound length, and type of retractor (retractors with or without an inner-ring).

RESULTS

Logistic multivariate regression analysis revealed that a retractor with an inner-ring use (odds ratio 3.28, 95% CI 1.41-7.63, P = 0.006) and younger age (odds ratio 1.07 per month, 95% CI 1.02-1.12, P = 0.010) were independent risk factors associated with hypotension following lower abdominal surgery in this age group.

CONCLUSIONS

Patient age and use of a wound retractor with an inner-ring are independent risk factors associated with hypotension during insertion of the abdominal retractor in lower abdominal surgery.

Predictors of intraoperative hypotension and bradycardia

BACKGROUND

Perioperative hypotension and bradycardia in the surgical patient are associated with adverse outcomes, including stroke. We developed and evaluated a new preoperative risk model in predicting intraoperative hypotension or bradycardia in patients undergoing elective noncardiac surgery.

METHODS

Prospective data were collected in 193 patients undergoing elective, noncardiac surgery. Intraoperative hypotension was defined as systolic blood pressure <90 mm Hg for >5 minutes or a 35% decrease in the mean arterial blood pressure. Intraoperative bradycardia was defined as a heart rate of <60 beats/min for >5 minutes. A logistic regression model was developed for predicting intraoperative hypotension or bradycardia with bootstrap validation. Model performance was assessed using area under the receiver operating curves and Hosmer-Lemeshow tests.

RESULTS

A total of 127 patients developed hypotension or bradycardia. The average age of participants was 67.6 ± 11.3 years, and 59.1% underwent major surgery. A final 5-item score was developed, including preoperative Heart rate (<60 beats/min), preoperative hypotension (<110/60 mm Hg), Elderly age (>65 years), preoperative renin-Angiotensin blockade (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta-blockers), Revised cardiac risk index (≥3 points), and Type of surgery (major surgery), entitled the "HEART" score. The HEART score was moderately predictive of intraoperative bradycardia or hypotension (odds ratio, 2.51; 95% confidence interval, 1.79-3.53; C-statistic, 0.75). Maximum points on the HEART score were associated with an increased likelihood ratio for intraoperative bradycardia or hypotension (likelihood ratio, +3.64).

CONCLUSIONS

The 5-point HEART score was predictive of intraoperative hypotension or bradycardia. These findings suggest a role for using the HEART score to better risk-stratify patients preoperatively and may help guide decisions on perioperative management of blood pressure and heart rate-lowering medications and anesthetic agents.

A presedation fluid bolus does not decrease the incidence of propofol-induced hypotension in pediatric patients

BACKGROUND AND OBJECTIVE

Propofol is commonly used in pediatric sedation, which may cause hypotension during induction. Our goal was to determine the effect of a preinduction 20-mL/kg isotonic fluid bolus on propofol-induced hypotension, assess clinical signs of hypoperfusion during hypotension, and evaluate for age-related propofol dosing differences.

METHODS

This prospective, randomized, controlled, nonblinded study was conducted at Children's Hospital of Illinois. Patients were children 6 to 60 months of age who needed sedation for MRI or auditory brainstem-evoked response testing. The treatment group received a preinduction 20-mL/kg isotonic saline bolus before procedure initiation. Patients were continuously monitored via cardiorespiratory monitor with pulse oximetry and end-tidal carbon dioxide measurements. Cardiovascular indices and clinical signs of hypoperfusion were compared between groups, and propofol dosing differences were compared between age groups.

RESULTS

One hundred twenty-six patients were randomly assigned to treatment (n=52) or control (n=74) conditions. Twelve patients in the treatment group and 14 patients in the control group experienced postinduction hypotension, as defined by the Pediatric Advanced Life Support guidelines. One patient in each group was given volume resuscitation when blood pressure did not improve after a reduction in the propofol infusion rate. No hypotensive patients had physical signs of hypoperfusion, and patients≤1 year of age needed significantly more propofol.

CONCLUSIONS

A 20-mL/kg preinduction isotonic saline bolus does not prevent propofol-induced hypotension. No clinical signs of hypoperfusion were noted with induced hypotension, and infants≤12 months old need significantly more propofol per kilogram for procedures.

All this monitoring…what's necessary, what's not?

The goal of perioperative monitoring is to aid the clinician in optimizing care to achieve the best possible survival with the lowest possible morbidity. Ideally, we would like to have monitoring that can rapidly and accurately identify perturbations in circulatory well-being that would permit timely intervention and allow for restoration before the patient is damaged. The evidence to support the use of our standard monitoring strategies (continuous electrocardiography, blood pressure, central venous pressure, oxygen saturation and capnography) is based on expert opinion, case series, or at best observational studies. While these monitoring parameters will identify life-threatening events, they provide no direct information concerning the oxygen economy of the patient. Nevertheless, they are mandated by professional societies representing specialists in cardiac disease, critical care, and anesthesiology. Additional non-routine monitoring strategies that provide data concerning the body's oxygen economy, such as venous saturation monitoring and near infrared spectroscopy, have shown promise in prospective observational studies in managing these complex groups of patients. Ideally, high-level evidence would be required before adopting these newer strategies, but in the absence of new funding sources and the challenges of the wide variation in practice patterns between centers, this seems unlikely. The evidence supporting the current standard perioperative monitoring strategies will be reviewed. In addition, evidence supporting non-routine monitoring strategies will be reviewed and their potential for added benefit assessed.

Near-infrared spectroscopy: exposing the dark (venous) side of the circulation

The safety of anesthesia has improved greatly in the past three decades. Standard perioperative monitoring, including pulse oximetry, has practically eliminated unrecognized arterial hypoxia as a cause for perioperative injury. However, most anesthesia-related cardiac arrests in children are now cardiovascular in origin, and standard monitoring is unable to detect many circulatory abnormalities. Near-infrared spectroscopy provides noninvasive continuous access to the venous side of regional circulations that can approximate organ-specific and global measures to facilitate the detection of circulatory abnormalities and drive goal-directed interventions to reduce end-organ ischemic injury.

Cerebral blood flow in the neonate

Ensuring adequate oxygenation of the developing brain is the cornerstone of neonatal critical care. Despite decades of clinical research dedicated to this issue of paramount importance, our knowledge and understanding regarding the physiology and pathophysiology of neonatal cerebral blood flow are still rudimentary. This review primarily focuses on currently available human clinical and experimental data on cerebral blood flow and autoregulation in the preterm and term infant. Limitations of systemic blood pressure values as surrogates for monitoring adequate cerebral oxygen delivery are discussed. Particular emphasis is placed on the high interindividual variability in cerebral blood flow values, vasoreactivity, and autoregulatory thresholds making the applications of normative values highly questionable. Technical and ethical difficulties to conduct such trials leave us with a near complete lack of knowledge on how pharmacological and surgical interventions impact on cerebral autoregulation. The ensemble of these works argues for the necessity of highly individualized care by taking advantage of continuous bedside monitoring of cerebral circulation. They also point to the urgent need for further studies addressing the exciting but difficult issue of cerebral blood flow autoregulation in the neonate.

Brain monitoring in children

Applying scalp sensors in the operating theater, intensive care, or resuscitation scenarios to detect and monitor brain function is achievable, practical, and affordable. The modalities are complex and the output of the monitor needs careful interpretation. The monitor may have technical problems, and a single reading must be considered with caution. These monitors may have a use for monitoring trends in specific situations, but evidence does not support their widespread use. Nevertheless, research should continue to investigate their role. Future techniques and treatments may show that these monitors can monitor brain function and prevent harm.

A child with a difficult airway: what do I do next?

PURPOSE OF REVIEW

Difficulties in pediatric airway management are common and continue to result in significant morbidity and mortality. This review reports on current concepts in approaching a child with a difficult airway.

RECENT FINDINGS

Routine airway management in healthy children with normal airways is simple in experienced hands. Mask ventilation (oxygenation) is always possible and tracheal intubation normally simple. However, transient hypoxia is common in these children usually due to unexpected anatomical and functional airway problems or failure to ventilate during rapid sequence induction. Anatomical airway problems (upper airway collapse and adenoid hypertrophy) and functional airway problems (laryngospasm, bronchospasm, insufficient depth of anesthesia and muscle rigidity, gastric hyperinflation, and alveolar collapse) require urgent recognition and treatment algorithms due to insufficient oxygen reserves. Early muscle paralysis and epinephrine administration aids resolution of these functional airway obstructions. Children with an 'impaired' normal (foreign body, allergy, and inflammation) or an expected difficult (scars, tumors, and congenital) airway require careful planning and expertise. Training in the recognition and management of these different situations as well as a suitably equipped anesthesia workstation and trained personnel are essential.

SUMMARY

The healthy child with an unexpected airway problem requires clear strategies. The 'impaired' normal pediatric airway may be handled by anesthetists experienced with children, whereas the expected difficult pediatric airway requires dedicated pediatric anesthesia specialist care and should only be managed in specialized centers.

Using magnetic resonance imaging for early assessment of submucous cleft palate: a case report

Surgical correction for submucous cleft palate is generally indicated in the presence of velopharyngeal inadequacy. Clinical assessment of velopharyngeal inadequacy requires that the child is able to produce a connected speech sample, which can yield a delay in treatment decisions that extends through a critical period of speech and language development. A perceptual speech assessment and intraoral examination are traditionally the most important methods of establishing a diagnosis of submucous cleft palate. The purpose of this case report is to demonstrate the use of magnetic resonance imaging as a diagnostic tool to provide early identification and an indication of surgical treatment for an individual born with a submucous cleft palate. The magnetic resonance images indicated a discontinuous levator veli palatini muscle sling arrangement with attachment of the muscle bundles onto the hard palate. Surgery was performed at 16 months and postsurgical speech evaluations demonstrated normal resonance and age-appropriate speech.

Recent advances in pediatric anesthesia

Writing about advances in a field of medicine normally includes some pride about progress which one was witness to or even a participant in. The younger one is, the more enthusiastically every advance is lauded and welcomed. This is human nature and nothing to be complained about. However, when anesthesiologists, having worked and struggled in the field of pediatric anesthesia for about 40 years, look back to past advances, a more realistic, even painful picture comes to mind. There was a price which a considerable number of patients had to pay for progress, ruined health or even death. This experience of decades of practice is rarely presented in the literature but should not be forgotten when we proudly remember advances in pediatric anesthesia.

Anesthesia for noncardiac procedures for children with a Berlin Heart EXCOR Pediatric Ventricular Assist Device: a case series

OBJECTIVES

To report our experience of providing anesthesia for noncardiac procedures in children with in situ Berlin Heart EXCOR Pediatric ventricular assist devices and to suggest principles of anesthetic management.

BACKGROUND

With the initiation of the first North American training and support center for Berlin Heart at our institution in 2006, we have been asked to provide anesthesia for noncardiac procedures to these children. No current anesthetic approach to these children has been reported.

METHODS/MATERIALS

Anesthetic records for all noncardiac procedures for children with Berlin Heart between August 2006 and February 2009 in a tertiary care pediatric hospital were retrospectively reviewed. Charts were reviewed for demographic and clinical data, perioperative management, and occurrence of hypotension.

RESULTS

Twenty-nine procedures were performed on 11 patients. Hypotension was a common occurrence with all anesthetic induction and maintenance agents even at low doses. Ketamine induction, however, was less likely to produce hypotension, odds ratio for hypotension 0.1333 (95% confidence range 0.021-0.856). Hypotension was responsive to fluid bolus (60%) and alpha-receptor agonists (100%). Preoperative stability and presence of biventricular ventricular assist device (BiVAD) did not predict intraoperative hemodynamic course.

CONCLUSIONS

Unlike patients with other ventricular assist devices, these children do not tolerate reductions in systemic vascular resistance (SVR) because of the relatively fixed cardiac output of this device. Agents that reduce SVR should be avoided where possible. Preoperative stability is not predictive. Fluids and alpha-agonists should be first-line response to hypotension in this population. Further study of this unusual population is warranted to further delineate best anesthetic practice.

How do pediatric anesthesiologists define intraoperative hypotension?

INTRODUCTION

Although blood pressure (BP) monitoring is a recommended standard of care by the ASA, and pediatric anesthesiologists routinely monitor the BP of their patients and when appropriate treat deviations from 'normal', there is no robust definition of hypotension in any of the pediatric anesthesia texts or journals. Consequently, what constitutes hypotension in pediatric anesthesia is currently unknown. We designed a questionnaire-based survey of pediatric anesthesiologists to determine the BP ranges and thresholds used to define intraoperative hypotension (IOH).

METHODS

Members of the Society of Pediatric Anesthesia (SPA) and the Association of Paediatric Anaesthetists (APA) of Great Britain and Ireland were contacted through e-mail to participate in this survey. We asked a few demographic questions and five questions about specific definitions of hypotension for different age groups of patients undergoing inguinal herniorraphy, a common pediatric surgical procedure.

RESULTS

The overall response rate was 56% (483/860), of which 76% were SPA members. Majority of the respondents (72%) work in academic institutions, while 8.9% work in institutions with fewer than 1000 annual pediatric surgical caseload. About 76% of respondents indicated that a 20-30% reduction in baseline systolic blood pressure (SBP) indicates significant hypotension in children under anesthesia. Most responders (86.7%) indicated that they use mean arterial pressure or SBP (72%) to define IOH. The mean SBP values for hypotension quoted by SPA members was about 5-7% lower across all pediatric age groups compared to values quoted by APA members (P = 0.001 for all age groups).

CONCLUSIONS

There is great variability in the BP parameters used and the threshold used for defining and treating IOH among pediatric anesthesiologists. The majority of respondents considered a 20-30% reduction from baseline in SBP as indicative of significant hypotension. Lack of a consensus definition for a common clinical condition like IOH could have implications for patient care as well as future clinical research.