Subtype-independent near full-length HIV-1 genome sequencing and assembly to be used in large molecular epidemiological studies and clinical management

Introduction

HIV-1 near full-length genome (HIV-NFLG) sequencing from plasma is an attractive multidimensional tool to apply in large-scale population-based molecular epidemiological studies. It also enables genotypic resistance testing (GRT) for all drug target sites allowing effective intervention strategies for control and prevention in high-risk population groups. Thus, the main objective of this study was to develop a simplified subtype-independent, cost- and labour-efficient HIV-NFLG protocol that can be used in clinical management as well as in molecular epidemiological studies.

Methods

Plasma samples (n=30) were obtained from HIV-1B (n=10), HIV-1C (n=10), CRF01_AE (n=5) and CRF01_AG (n=5) infected individuals with minimum viral load >1120 copies/ml. The amplification was performed with two large amplicons of 5.5 kb and 3.7 kb, sequenced with 17 primers to obtain HIV-NFLG. GRT was validated against ViroSeq™ HIV-1 Genotyping System.

Results

After excluding four plasma samples with low-quality RNA, a total of 26 samples were attempted. Among them, NFLG was obtained from 24 (92%) samples with the lowest viral load being 3000 copies/ml. High (>99%) concordance was observed between HIV-NFLG and ViroSeq™ when determining the drug resistance mutations (DRMs). The N384I connection mutation was additionally detected by NFLG in two samples.

Conclusions

Our high efficiency subtype-independent HIV-NFLG is a simple and promising approach to be used in large-scale molecular epidemiological studies. It will facilitate the understanding of the HIV-1 pandemic population dynamics and outline effective intervention strategies. Furthermore, it can potentially be applicable in clinical management of drug resistance by evaluating DRMs against all available antiretrovirals in a single assay.     

Antiretroviral treatment outcome in HIV-1-infected patients routinely followed up in capital cities and remote areas of Senegal,Mali and Guinea-Conakry

Introduction

Access to antiretroviral treatment (ART) becomes more and more effective in resource-limited settings (RLS). However, this global effort would be even more profitable if the access to laboratory services especially in decentralized settings was strengthened. We report the virological outcome and HIV-1 drug resistance in three West African countries using dried blood spots (DBS) samples.

Methods

We included HIV-1-infected adults on ART ≥6 months and followed up in capital cities and decentralized sites in Senegal, Mali and Guinea-Conakry. Patients were consecutively enrolled and DBS were collected in field conditions and kept at ambient temperature before transfer to the reference laboratory. Viral load (VL) was quantified using the NucliSENS EasyQ HIV-1 v1.2. Genotyping of HIV-1 pol gene was performed using in-house protocol.

Results

Of the 407 participants, 119, 152 and 136 were from Senegal, Mali and Guinea-Conakry, respectively. The median treatment duration was 36 months [IQR: 6–136]. Virological failure (VF) (VL≥3log₁₀ copies/mL) was observed in 26% (95% confidence interval (CI), 18–35; n=31), 11% (95% CI, 6–17; n=16) and 24% (95% CI, 17–32; n=33) of patients in Senegal, Mali and Guinea-Conakry, respectively (p=0.001). Of samples presenting VL≥3log₁₀ copies/mL (n=80), 70 were successfully genotyped. At least one drug resistance mutation (DRM) was detected in the following proportions: 70% (95% CI, 50–86; n=19), 93% (95% CI, 68–100; n=14) and 68% (95% CI, 48–84; n=19) in Senegal, Mali and Guinea-Conakry, respectively (p=0.22). Twenty-six per cent (26%; 95% CI, 16–38; n=18) of patients in VF harboured wild-type viruses, which is likely indicative of weak adherence. Phylogenetic analysis showed the predominance of CRF02_AG subtype (73%; 95% CI, 61–83; n=51).

Conclusions

We describe the ART outcome in capital and rural settings of Senegal, Mali and Guinea-Conakry. Our results in all of the three countries highlight the need to reinforce the ART adherence in order to minimize the occurrence of drug resistance. In addition, these findings provide additional evidence that the use of DBS as a sampling support could assist virological monitoring of patients on ART in remote areas.     

Capacity building and predictors of success for HIV-1 drug resistance testing in the Asia-Pacific region and Africa

Background

The TREAT Asia Quality Assessment Scheme (TAQAS) was developed as a quality assessment programme through expert education and training, for laboratories in the Asia-Pacific and Africa that perform HIV drug-resistance (HIVDR) genotyping. We evaluated the programme performance and factors associated with high-quality HIVDR genotyping.

Methods

Laboratories used their standard protocols to test panels of human immunodeficiency virus (HIV)-positive plasma samples or electropherograms. Protocols were documented and performance was evaluated according to a newly developed scoring system, agreement with panel-specific consensus sequence, and detection of drug-resistance mutations (DRMs) and mixtures of wild-type and resistant virus (mixtures). High-quality performance was defined as detection of ≥95% DRMs.

Results

Over 4.5 years, 23 participating laboratories in 13 countries tested 45 samples (30 HIV-1 subtype B; 15 non-B subtypes) in nine panels. Median detection of DRMs was 88–98% in plasma panels and 90–97% in electropherogram panels. Laboratories were supported to amend and improve their test outcomes as appropriate. Three laboratories that detected <80% DRMs in early panels demonstrated subsequent improvement. Sample complexity factors – number of DRMs (p<0.001) and number of DRMs as mixtures (p<0.001); and laboratory performance factors – detection of mixtures (p<0.001) and agreement with consensus sequence (p<0.001), were associated with high performance; sample format (plasma or electropherogram), subtype and genotyping protocol were not.

Conclusion

High-quality HIVDR genotyping was achieved in the TAQAS collaborative laboratory network. Sample complexity and detection of mixtures were associated with performance quality. Laboratories conducting HIVDR genotyping are encouraged to participate in quality assessment programmes.     

Additive contribution of nitrous oxide to halothane MAC in infants and children

Fifty-one infants and small children (14.7 +/- 7.2 mo) were studied to determine the MAC of halothane in O2 (n = 11) and in the presence of three different nitrous oxide (N2O) concentrations (25% [n = 13], 50% [n = 13], and 75% [n = 14]). In the three N2O groups, after randomly assigning patients to an N2O group, anesthesia was induced with halothane and N2O using a pediatric circle system. After endotracheal intubation, halothane and N2O end-expired concentrations were adjusted to predetermined concentrations. The initial halothane concentrations in each group were based on the assumption that each percent N2O reduced halothane concentrations by 0.01 vol % (assumed halothane MAC = 1.0 vol %). Based on the response of the preceding subject in each group, halothane concentrations were increased or decreased depending on whether the response was to move or not to move, respectively, in response to the surgical incision. The mean duration of constant end-tidal concentrations before skin incision was 10 min. End-tidal gases were sampled and measured from a separate distal sampling port of an endotracheal tube during controlled ventilation (Perkin-Elmer Mass Spectrometer). The MAC value for halothane in O2 was 0.94 +/- 0.08 vol % (mean +/- SD). The MAC values of halothane in the presence of 25%, 50%, and 75% N2O were 0.78 +/- 0.12 vol %, 0.44 +/- 0.10 vol %, and 0.29 +/- 0.06 vol %, respectively. All concentrations of N2O significantly reduced the MAC of halothane. A regression analysis through all four data points yielded a linear relationship (r2 = 0.87) with a predicted MAC for N2O of 105 vol %. Unlike halothane and isoflurane, the predicted MAC of N2O in infants and children is similar to that reported by others in adults. Similar to the results of clinical studies in adults, the contribution of N2O to halothane MAC in children is additive.     

Prospective, interdisciplinary follow-up of children with prenatally diagnosed giant omphalocele: short-term neurodevelopmental outcome

Purpose

The objective of this study is to determine the short-term neurodevelopmental outcome in infants with giant omphalocele (GO).

Materials and Methods

Between January 2002 and December 2007, 31 consecutive infants with GO received prenatal and postnatal care at our institution. Overall survival was 81% (25/31). Twenty (80%) of the survivors were enrolled in a prospective interdisciplinary follow-up program. Fifteen were at least 6 months of age and received detailed neurodevelopmental evaluation using the Bayley Scales of Infant Development II (BSID-II [before 2006, n = 3]) or BSID-III (after 2006, n = 12). Scores were grouped as average, mildly delayed, and severely delayed by SD intervals (115-85, 71-84, <70). Scores were considered mixed if cognitive or language skills were in different ranges.

Results

Median age at evaluation was 12 months (range, 6-26 months). Average, mildly delayed, and severely delayed scores for cognitive and language skills were found in 6 (40%), 2 (13%), and 6 (40%), respectively. One child had mixed scores (severely delayed for cognitive and mildly delayed for language skills). Motor scores were normal, mildly delayed, and severely delayed in 6 (40%), 2 (13%), and 7 (47%), respectively. The neuromuscular examination was abnormal in 8 patients (62%). Five (33%) scored within the average range, whereas 6 (40%) demonstrated severe delays for cognitive, language, and motor outcome. Of the 6 children with severe delays, 2 (13% of total) have autism, 4 required tracheostomy, and 1 was diagnosed with Williams syndrome.

Conclusions

The presence of GO is associated with deficits in developmental achievements in most of the affected infants ranging from mild to profound delays. These findings underscore the importance of early and standardized neurodevelopmental evaluation throughout childhood for all survivors with GO. Larger studies are warranted for risk factor stratification.     

Monosegmental living donor liver transplantation

BACKGROUND: Living donor liver transplant (LDLT) program has been started from 1990 in Japan, and is still major form of liver transplantation because of the scarcity of cadaveric donor organs. In small infants, implantation of left lateral segment grafts can be a problem because of a large-for-size graft. Until November 2002, we performed 867 transplants for 828 patients (561 children and 306 adults), and 14 cases received monosegment grafts from living donors. METHODS: Fifteen patients, median age 211 days, median weights 5.95 kg, received monosegmental LDLT. The indication for using this technique was infants with an estimated graft-to-recipient weight ratio of over 4.0%. RESULTS: Graft and patient survival is 85.7%. There were no differences in donor operation time and blood loss between monosegmentectomy and left lateral segmentectomy. Segment III grafts were indicated in 13 cases. Two vascular complications were observed (one hepatic artery thrombosis and one portal vein thrombosis). CONCLUSIONS: Monosegental living donor liver transplantation is a feasible option with satisfactory graft survival in small babies with liver failure.     

Review of the Diagnoses Predisposing Infants to Intestinal Failure on Hospitalized Parenteral Nutrition

During the last 3 decades the use of parenteral nutrition (PN) and the aggressive introduction of enteral feeding in daily practice have transformed the outcome for even the sickest of these infants. More than 90% of infants and children now survive after extensive small bowel resection in the neonatal period. During the last 3 decades the use of parenteral nutrition (PN) and the aggressive introduction of enteral feeding in daily practice have transformed the outcome for even the sickest of these children. The aim of this study was to review the diagnoses (other than infants purely premature) that predispose infants to intestinal failure (IF) and dependency on PN as well as their outcomes. A total of 63 children less than 1 year old received PN for more than 28 days including 35 (56%) boys; 29% of cases were preterm infants with a median gestational age of 26.5 weeks (range, 24-33 weeks). The median age at the start of PN was 0.25 years or 3 months. Median duration of PN treatment was 62 days and median duration of hospitalization was 128 days. Twenty-three (36.5%) children had a primary nondigestive disorder (PNDD) and 40 (63.5%), a primary digestive disorder (PDD). Forty (63.5%) children with severe intestinal failure were successfully weaned off PN; whereas 8 (13%) infants with severe gastrointestinal diseases remained dependent on IV nutrition. Fourteen (22%) patients died. Infants less than 1 year of age with severe intestinal failure have up to a 75% survival rate, with a 65% chance of achieving intestinal autonomy. For children presenting with PDD in infancy, there is a high risk of needing long-term PN.     

A molecular epidemiological investigation of PEDV in China: Characterization of co‐infection and genetic diversity of S1‐based genes

Porcine epidemic diarrhoea virus (PEDV) is an emerging and re‐emerging epizootic virus of swine that causes substantial economic losses to the pig industry in China and other countries. The variations in the virus, and its co‐infections with other enteric viruses, have contributed to the poor control of PEDV infection. In the current study, a broad epidemiological investigation of PEDV was carried out in 22 provinces or municipalities of China during 2015–2018. The enteric viruses causing co‐infection with PEDV and the genetic diversity of the PEDV S1 gene were also analysed. The results indicated that, of the 543 diarrhoea samples, 66.85% (363/543) were positive for PEDV, and co‐infection rates of PEDV with 13 enteric viruses ranged from 3.58% (13/363) to 81.55% (296/363). Among these enteric viruses, the signs of diarrhoea induced by PEDV were potentially associated with co‐infections with porcine enterovirus 9/10 (PEV) and torque teno sus virus 2 (TTSuV‐2) (p < .05). The 147 PEDV strains identified in our study belong to Chinese pandemic strains and exhibited genetic diversity. The virulence‐determining S1 proteins of PEDV pandemic strains were undergoing amino acid mutations, in which S58_S58insQGVN–N135dup–D158_I159del‐like mutations were common patterns (97.28%, 143/147). When compared with 2011–2014 PEDV strains, the amino acid mutations of PEDV pandemic strains were mainly located in the N‐terminal domain of S1 (S1‐NTD), and 21 novel mutations occurred in 2017 and 2018. Furthermore, protein homology modelling showed that the mutations in pattern of insertion and deletion mutations of the S1 protein of PEDV pandemic strains may have caused structural changes on the surface of the S1 protein. These data provide a better understanding of the co‐infection and genetic evolution of PEDV in China.     

Mortality in a cohort of children born to HIV-1 infected women from Durban, South Africa.

OBJECTIVES: To describe mortality in a cohort of infants with vertically transmitted HIV-1 infection. PATIENTS AND METHODS: Children of HIV-1 infected women were followed up from birth and a record was made at each visit of growth, development and all illnesses. Details surrounding death were obtained from hospital records. RESULTS: The final cohort comprised 48 infected and 93 uninfected children; there were 25 deaths, 17 of which (35%) were regarded as being HIV-related. The mean age at death of HIV-related cases was 10.1 months (range 1-48 months), with 83% of HIV-related deaths occurring before the age of 10 months. The commonest diagnoses at the time of death were diarrhoea, pneumonia, failure to thrive and severe thrush. These findings, together with neurological abnormalities, often presaged rapid deterioration and death. CONCLUSIONS: Mortality among children with vertically acquired HIV infection is high in the first year of life. Death in these subjects was due to the common causes of morbidity and mortality among all children in developing countries. A combination of diarrhoea, pneumonia, failure to thrive, and neurological abnormalities should alert one to the possibility of rapidly progressive disease and death.     

Infant burns: A single institution retrospective review

Thermal injuries amongst infants are common and a cause of significant mortality and morbidity in South Africa. This has been attributed to the lack of an enabling environment (poverty-related lack of safe living conditions) and the cognitive and physical developmental immaturity of infants, who depend on their surroundings and adults to keep them safe. This is a retrospective observational study of 548 infant admissions over 48 months. Infant was defined as children below 13 months of age. The 548 infants constituted 23% of all paediatric burn admissions of ages 0–12 years. Three hundred and fourteen were males (57%) and 234 (42.7%) females. The infants were divided in a pre-ambulatory group of 143 (26%) infants of 0–6 months and an ambulatory group of 7 months to 12 months consisting of 457 (83.3%). The total body surface area (TBSA) ranged from 2–65%. Seventy-six percent (417 infants) occurred in the home environment. Scalds accounted for 86% (471 infants) and 6% (33 infants) were as a result of flame burns. Non-accidental injuries accounted for 1.2%. The anatomical distributions varied between the pre-ambulatory and ambulatory groups. Conservative management was done in 397 (72.4%) and 101(18.4%) infants underwent surgery. Infection was suspected in 76 (13.5%) infants with positive blood cultures in 15(20%) of the 76. ICU care was received in 46 (8.3%) infants and 15 (32.6%) of these had inhalation injuries. Of the inhalation injuries 11(23.9%) infants underwent mechanical ventilation of an average of 4.4 days. Ventilator associated pneumonia was diagnosed in 8(17%) of the ventilated children. The mortality rate was 0.36%. The surgically treated patients acquired more complications than the conservatively treated group. Special treatment considerations should be considered in this paediatric sub-group.     

小儿卡波西型血管内皮瘤的个体化治疗分析

目的总结分析小儿卡波西型血管内皮瘤（KHE）的临床特点，探讨其个体化治疗策略。 方法回顾性分析2016年1月至2020年3月江西省儿童医院收治的20例KHE患儿的临床资料，总结病例的临床特征、肿瘤性状、是否合并卡萨巴赫-梅里特现象（KMP）、治疗策略及转归等特点。 结果20例KHE患儿中女6例，男14例。年龄<1岁的患儿16例（80.0%），其中13例（65.0%）出生时即发现。合并KMP的患儿有8例，合并KMP与不合并KMP患儿在瘤体大小（P=0.009）、是否侵犯深部肌肉（P=0.003）的差异有统计学意义。合并KMP患儿中3例病灶行网状缝扎治疗，5例口服西罗莫司治疗；1例网状缝扎治疗无效后联合口服西罗莫司治疗。不合并KMP的12例患儿中，7例行肿瘤完全切除，2例行肿瘤部分切除后联合口服激素，2例病灶行网状缝扎治疗，1例口服西罗莫司；1例网状缝扎治疗无效后联合口服西罗莫司治疗。随访2~5年，合并KMP的患儿中1例实现瘤体接近消失，7例带瘤生存；不合并KMP的患儿中7例肿瘤完全切除，未见复发，5例无症状带瘤生存。 结论大多数KHE为婴儿期发病，肿瘤大小、病灶累及深部肌肉情况与患儿是否合并KMP相关。对于合并KMP的患儿，初步予以激素冲击治疗或输注血液制品稳定病情，病灶合适病例可先单纯进行网状缝扎治疗；如病灶不适合网状缝扎术或治疗无效，可单用或联合口服西罗莫司治疗。     

Intramuscular rocuronium in infants and children: a multicenter study to evaluate tracheal intubating conditions, onset, and duration of action.

BACKGROUND: This multicenter, assessor-blinded, randomized study was done to confirm and extend a pilot study showing that intramuscular rocuronium can provide adequate tracheal intubating conditions in infants (2.5 min) and children (3 min) during halothane anesthesia. METHODS: Thirty-eight infants (age range, 3-12 months) and 38 children (age range, 1 to 5 yr) classified as American Society of Anesthesiologists physical status 1 and 2 were evaluated at four investigational sites. Anesthesia was maintained with halothane and oxygen (1% end-tidal concentration if <2.5 yr; 0.80% end-tidal concentration if >2.5 yr) for 5 min. One half of the patients received 0.45 mg/kg intravenous rocuronium. The others received 1 mg/kg (infants) or 1.8 mg/kg (children) of intramuscular rocuronium into the deltoid muscle. Intubating conditions and mechanomyographic responses to ulnar nerve stimulation were assessed. RESULTS: The conditions for tracheal intubation at 2.5 and 3 min in infants and children, respectively, were inadequate in a high percentage of patients in the intramuscular group. Nine of 16 infants and 10 of 17 children had adequate or better intubating conditions at 3.5 and 4 min, respectively, after intramuscular rocuronium. Better-than-adequate intubating conditions were achieved in 14 of 15 infants and 16 of 17 children given intravenous rocuronium. Intramuscular rocuronium provided > or =98% blockade in 7.4+/-3.4 min (in infants) and 8+/-6.3 min (in children). Twenty-five percent recovery occurred in 79+/-26 min (in infants) and in 86+/-22 min (in children). CONCLUSIONS: Intramuscular rocuronium, in the doses and conditions tested, does not consistently provide satisfactory tracheal intubating conditions in infants and children and is not an adequate alternative to intramuscular succinylcholine when rapid intubation is necessary.     

Transtubular potassium concentration gradient: a useful test to estimate renal aldosterone bio-activity in infants and children

The present investigation was designed to validate the usefulness of transtubular potassium (K) concentration gradient (TTKG) as an indicator of aldosterone bio-activity in infants and children. TTKG was calculated by the formula: [K]urine: (urine/plasma)osmolality/[K]venous blood. We compared this index with fractional K excretion (FEK) and urine K concentration to urine sodium (Na) concentration ratio (UK/UNa) in 473 normal children aged 1 month-15 years. Values of TTKG followed a non-gaussian distribution (median, 6.3; 3rd centile, 4.1; 97th centile, 13.4). TTKG in infants (n = 108; median, 7.8) was significantly higher than in children (n = 365; median, 6.0). TTKG correlated directly with FEK and UK/UNa. Indices of K excretion were also assessed in 13 patients with hypo- and pseudohypoaldosteronism. TTKG values varied between 1.6 and 4.1 and were all below the 3rd percentile established for the age of the subject. We conclude that calculation of TTKG is an easy and sensitive method for the evaluation of mineralocorticoid action in distal and collecting tubules.     

Review of historical cohort: ursodeoxycholic acid in extrahepatic biliary atresia

Background

Ursodeoxycholic acid is a bile acid that was found to increase bile flow, protect hepatocytes, and dissolve gallstones.

Purpose

The objective of this study is to review ursodeoxycholic acid in infants and children with extrahepatic biliary atresia.

Methods

We used a statistical analysis of data of records of infants and children having extrahepatic biliary atresia who underwent Kasai portoenterostomy and attended Hepatology Clinic, New Children's Hospital, Cairo University, Egypt, from May 1985 until June 2005.

Results

Of 141 infants with extrahepatic biliary atresia, 108 received ursodeoxycholic acid for mean duration ± SD of 252.6 ± 544.9 days in a dosage of 20 mg/kg per day. The outcome of infants who did not receive ursodeoxycholic acid and those who did was the following: 8 (24.2%) and 11 (10.18%) had a successful outcome (P = .043), 0 (0%) and 7 (6.4%) improved (P = .148), 25 (75.7%) and 84 (77.7%) had a failed outcome (P = .489), and none vs 5 died (4.6%) (P = .135), respectively. The predictors of successful outcomes were age less than 65 days at portoenterostomy (P = .008) and absence of ursodeoxycholic acid intake (P = .04) with a likelihood of a successful outcome that was 2.8, that associated with ursodeoxycholic acid intake.

Conclusion

In this cohort of infants with extrahepatic biliary atresia, ursodeoxycholic acid was not shown to be effective, and its use was associated with a plethora of hepatic and extrahepatic complications.     

Study of the regulatory properties of glucokinase by site-directed mutagenesis: conversion of glucokinase to an enzyme with high affinity for glucose

To identify the amino acids involved in the specific regulatory properties of glucokinase, and particularly its low affinity for glucose, mutants of the human islet enzyme have been prepared, in which glucokinase-specific residues have been replaced. Two mutations increased the affinity for glucose by twofold (K296M) and sixfold (Y214A), the latter also decreasing the Hill coefficient from 1.75 to 1.2 with minimal change in the affinity for ATP. Combining these two mutations with N166R resulted in a 50-fold decrease in the half-saturating substrate concentration (S0.5) value, which became then comparable to the Km of hexokinase II. The location of N166, Y214, and K296 in the three-dimensional structure of glucokinase suggests that these mutations act by favoring closure of the catalytic cleft. As a rule, mutations changed the affinity for glucose and for the competitive inhibitor mannoheptulose (MH) in parallel, whereas they barely affected the affinity for N-acetylglucosamine (NAG). These and other results suggest that NAG and MH bind to the same site but to different conformations of glucokinase. A small reduction in the affinity for the regulatory protein was observed with mutations of residues on the smaller domain and in the hinge region, confirming the bipartite nature of the binding site for the regulatory protein. The K296M mutant was found to have a threefold decreased affinity for palmitoyl CoA; this effect was additive to that previously observed for the E279Q mutant, indicating that the binding site for long-chain acyl CoAs is located on the upper face of the larger domain.     

Hemodynamic responses to nitrous oxide during inhalation anesthesia in pediatric patients

STUDY OBJECTIVE: To measure the hemodynamic changes produced by nitrous oxide (N2O) during halothane and isoflurane anesthesia in infants and children. DESIGN: A repeated measures design in two groups of infants and small children. SETTING: Operating rooms at a university hospital. PATIENTS: Nineteen healthy unmedicated infants and small children (mean age 12 months) who required elective surgery. INTERVENTIONS: Prior to anesthesia induction, cardiovascular measurements were recorded using pulsed Doppler and two-dimensional echocardiography. Following anesthesia induction with halothane (n = 10) or isoflurane (n = 9) in oxygen (O2) and air, anesthetic measures were stabilized at 1.0 minimum alveolar concentration (MAC) and cardiovascular measures were repeated. After 30% N2O was added to the 1.0 MAC anesthetic concentration, a third set of cardiovascular measurements was recorded. A final cardiovascular data set was measured 5 minutes following an increase in N2O concentration to 60%. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure (MAP), cardiac index (CI), stroke volume (SV), and ejection fraction (EF) decreased similarly and significantly at 1.0 MAC halothane and isoflurane. Heart rate (HR) increased during isoflurane anesthesia but decreased during halothane anesthesia. The addition of N2O resulted in a decrease in HR, CI, and MAP when compared to 1.0 MAC levels of halothane or isoflurane; however, SV and EF were not significantly changed from levels measured during 1.0 MAC halothane or isoflurane. CONCLUSIONS: The addition of N2O to halothane and isoflurane anesthesia in infants and children decreased HR. This decrease led to a decrease in cardiac output (CO). Unlike with adults, N2O did not produce cardiovascular signs of sympathetic stimulation in infants and children.