Pediatric Circle Research Articles

“Functional outcome in pediatric grade IV renal injuries following blunt abdominal trauma salvaged with minimally invasive interventions”

Non-operative management of higher-grade renal injuries has gradually become accepted in pediatric circles following multiple studies over the past decade which showed good renal salvage rates. However, some children do fail this conservative approach and need interventions which are mostly minimally invasive. There is still paucity of studies on the functional outcomes in this unique subgroup of patients. In this study, we review our management and functional outcome of children with grade IV renal injury due to blunt trauma of abdomen managed with minimally invasive interventions (MII) in a tertiary referral center. The present study seeks to summarize contemporary management of pediatric grade IV renal injury due to blunt trauma at our tertiary care center and to assess the functional outcomes in the subgroup who needed MII. A retrospective review was performed on children≤18 years with abdominal blunt trauma managed at our tertiary care facility over the past 10 years (January 2008-January 2018) to identify those with grade IV renal injuries. Data collected included demographic data like age, sex, mechanism of injury, incidence of hematuria, incidence of pre-existing urologic conditions, associated non-renal injuries, transfusion requirements, imaging findings, type of interventions, length of hospital stay, complications and outcomes on follow up. Review of our institutional database identified 10 children with grade IV renal injury. Mean age was 11.7±3.6 years (range, 6-18) and majority (6/10) were male. Motor vehicle collision and fall from heights were the commonest mechanisms of injury. While one patient responded to non-operative management, one girl needed emergency renal exploration and later nephrectomy. Eight needed minimally invasive interventions following initial non-operative management. One patient needed nephrectomy due to delayed hemorrhage while three patients needed delayed open reconstruction. The salvage rate in the group which needed interventions was 87.5% (7 of 8) however, the functional outcome was good only in 50% (4 of 8) of patients. The outcomes were better in those who were managed with MII earlier (3/4) compared to those who underwent delayed intervention (1/4). The median hospital stay was 11.5 days (range 7-34 days). Pediatric patients with non-exsanguinating grade IV renal injuries due to blunt trauma who fail non-operative management and need minimal invasive interventions have good renal salvage rates however, the functional outcomes are poorer. Judicious and early use of these minimally invasive interventions, instead of persisting with non-operative management can possibly improve these functional outcomes.

Organization of work of students’ pediatric scientific circle as an integral part of competence approach to training of future highly qualified specialists

Organization of work of students’ pediatric scientific circle as an integral part of competence approach to training of future highly qualified specialists

Comparison of low-fresh gas flow technique to standard technique of sevoflurane induction in children-A randomized controlled trial.

Although sevoflurane is preferred for inhalational induction in children, financial and environmental costs remain major limitations. The aim of this study was to determine if the use of low-fresh gas flow during inhalational induction with sevoflurane could significantly reduce agent consumption, without adversely affecting induction conditions. After institutional ethical committee approval, 50 children, aged 1-5years, undergoing ophthalmic procedures under general anesthesia, were randomized into two groups-standard induction (Group S) and low-flow induction (Group L). A pediatric circle system with 1L reservoir bag was primed with 8% sevoflurane in oxygen at 6Lmin-1 for 30seconds before beginning induction. In Group S, fresh gas flow was maintained at 6Lmin-1 until the end of induction. In Group L, fresh gas flow was reduced to 1Lmin-1 after applying facemask (time=T0). In both groups, sevoflurane was reduced to 5% after loss of eyelash reflex (T1). Once adequate depth of anesthesia was achieved (regular respiration, loss of muscle tone, and absence of movement to trapezius squeeze), intravenous access was secured (T2), followed by insertion of an appropriately sized LMA-Classic™ (T3). Heart rate and endtidal sevoflurane concentration were measured at each of the above time points, and at 15seconds following laryngeal mask airway insertion (T4). The total amount of sevoflurane consumed during induction was recorded. Sevoflurane consumption was significantly lower in Group L (4.17±0.70mL) compared to Group S (8.96±1.11mL) (mean difference 4.79 [95% CI=4.25-5.33] mL; P<0.001). Time to successful laryngeal mask airway insertion was similar in both groups. There were no significant differences in heart rate, incidence of reflex tachycardia, or need for rescue propofol. Induction of anesthesia with sevoflurane using low-fresh gas flow is effective in reducing sevoflurane consumption, without compromising induction time and conditions.

The closed circuit and the low flow systems

A breathing system is defined as an assembly of components, which delivers gases from the anesthesia machine to the patients’ airways. When the components are arranged as a circle, it is termed a circle system. The flow of exhaled gases is unidirectional in the system. The system contains a component (absorber), which absorbs exhaled carbon dioxide and it is not necessary to give high fresh gas flows as in Mapleson systems. When the adjustable pressure limiting (APL) valve is closed and all the exhaled gases without carbon dioxide are returned to the patient, the system becomes a totally closed one. Such a circle system can be used with flows as low as 250 to 500 mL and clinically can be termed as low-flow systems. The components of the circle system can be arranged in different ways with adherence to basic rules: (1) Unidirectional valve must be present between the reservoir bag and the patient on both inspiratory and expiratory sides; (2) fresh gas must not enter the system between the expiratory unidirectional valve and the patient; and (3) the APL valve must not be placed between the patient and the inspiratory unidirectional valve. The functional analysis is explained in detail. During the function, the arrangement of components is significant only at higher fresh gas flows. With the introduction of low resistance valves, improved soda lime canisters and low dead space connectors, the use of less complicated pediatric circle systems is gaining popularity to anesthetize children. There are bidirectional flow systems with carbon dioxide absorption. The Waters to and fro system, a classic example of bidirectional flow systems with a canister to absorb carbon dioxide, is valveless and portable. It was widely used in the past and now is only of historical importance.

National survey of pediatric breathing systems use in the UK*

To determine current practice in the use of pediatric breathing systems in the UK. Whilst the Ayres T-Piece has been used extensively in pediatric anesthesia for nearly six decades, the circle system has undergone recent modifications. These have enhanced its suitability for pediatric use. A postal questionnaire was sent to all consultant members of the Association of Paediatric Anaesthetists (APA). This asked about standard breathing systems for induction, maintenance, and ventilation during anesthesia in three groups of children (neonates, infants, and older children less than 20 kg). Additional questions included if anesthetic rooms were used and scavenging routinely employed. Replies were received from 337 members, giving a response rate of 75%. The T-Piece was the predominant breathing system for induction in all age groups but the circle appears popular for maintenance, particularly in older children. Anesthetic rooms were used by 97% for induction and scavenging used by only 60% when using a T-Piece. Despite significant improvements to the pediatric circle system and its practical advantages, the T-Piece remains the commonest breathing system used in smaller children by UK members of the APA.

Comparison of cuffed, uncuffed tracheal tubes and laryngeal mask airways in low flow pressure controlled ventilation in children

The use of low flow circle systems necessitates a 'leak free' breathing system which is commonly achieved by using a cuffed tracheal tube (TT). We hypothesized that low flow circle system anesthesia can equally effectively be achieved by using the LMA in pediatric anesthesia. Following local ethics committee approval we randomly recruited 45 patients scheduled for elective surgery and requiring mechanical ventilation into three groups (cuffed TT, uncuffed TT and LMA group, n = 15). The size of the TT was determined by means of the formula (age/4) + 4.5 for uncuffed and (age/4) + 4 for cuffed TT whereas the size of the LMA size was dependent on weight. Following induction of anesthesia and muscle paralysis patients were ventilated with pressure controlled ventilation through a pediatric circle system and the lowest fresh gas flow (FGF) determined. The FGF achieved were (median and range) 0.20 (0.2-0.25) l.min(-1) for the LMA group, 0.20 (0.2-0.4) l.min(-1) for the cuffed TT group and 1.15 (0.2-4.75) l.min(-1) for the uncuffed group. The differences between the LMA and cuffed TT compared with the uncuffed TT were significant (P < 0.0001 and P = 0.0002, respectively). The difference in FGF between LMA and cuffed TT was not significant. We conclude that pressure controlled ventilation using an LMA is an alternative to a cuffed TT during low flow circle system anesthesia in children. Low FGF is unlikely to be achieved consistently using an uncuffed TT because of a substantial leak.

The temperature and humidity of inspired gases in infants using a pediatric circle system: effects of high and low‐flow anesthesia

The effects of low-flow anesthesia on the temperature and humidity of the inspired gas in infants during mechanical ventilation is unknown. This study was designed to evaluate the temperature and humidity of the inspired gas in infants using a pediatric circle absorber system with high and low fresh gas flow (HFGF and LFGF) anesthesia. Twenty infants participated in this observational, sequential, cross-over study. Each infant was mechanically ventilated with a Kion Anesthesia Workstation, using a pediatric anesthesia circle circuit with both HFGF (6 l.min(-1)) and LFGF (0.6 l.min(-1)) technique. Airway temperature was recorded continuously at 16 sites throughout the breathing circuit. The relative humidity of the inspired gas was measured at the elbow connector adjacent to the CO2 sampling line. The mean airway temperatures of the inspired gas and the changes in mean airway temperatures throughout the breathing circuit during HFGF and LFGF did not differ significantly. The mean relative humidity of the inspired gas at steady state using a LFGF technique, 33.7 +/- 3.6%, was approximately threefold greater than it was with a HFGF technique, 11.9 +/- 5.1% (P < 0.05). Low-flow anesthesia with a pediatric circle system in infants neither increases the temperature of the inspired gas, nor achieves the minimum humidity of 50% reported to prevent ciliary damage, although the humidity during LFGF did increase threefold compared with HFGF. To maintain the temperature and humidity of the inspired gas during mechanical ventilation in infants, passive or active gas humidification should be used.

Effect of pre-medication on gastroduodenoscopy in isoflurane-anesthetized cats

The pre-medicant chosen may influence the ease with which gastroduodenoscopy (GD) is performed. The purpose of this study was to evaluate the relative ease of GD in cats under ketamine and isoflurane anesthesia after IM injection of hydromorphone (H, 0.1 mg kg−1), hydromorphone plus glycopyrrolate (HG, 0.1 mg kg−1 (H), 0.01 mg kg−1 (G)), medetomidine (M, 0.03 mg kg−1), or butorphanol (B, 0.4 mg kg−1). Eight cats were assigned randomly to receive each treatment in a cross-over design with at least 7 days between treatments. Twenty minutes after pre-medication, medetomidine produced greater (p = 0.001) sedation than the other treatments when assessed, using a subjective ordinal scale. The cats were injected with ketamine (10 mg kg−1 IM), orotracheally intubated, connected to a pediatric circle breathing system, and allowed to spontaneously breathe isoflurane in oxygen. Once end-tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was started. A single endoscopist (REG), who was unaware of the treatment used, performed all endoscopies. The endoscopist scored the difficulty of endoscopy subjectively (0–3). The significance of differences between treatments was evaluated using Friedman's test. Time for entering the stomach was 9.4 (4.7–15.9) (median (minimum–maximum)), 6.6 (5.2–11.7), 8.4 (6.3–16.5), and 7.7 (5.1–14.7) seconds and for entering the duodenum from the stomach was 20.5 (13.8–40.9), 18.2 (10.3–39.8), 20.2 (16.2–119.5), and 22.2 (11.8–83.8) seconds for H, HG, M, and B treatments, respectively. There were no significant differences in the time for, or difficulty of, endoscopy. We conclude that any of these drugs can be used satisfactorily at the doses and combinations tested to pre-medicate cats prior to general anesthesia for GD.

Comparison of the Jackson-Rees Circuit, the Pediatric Circle, and the MERA F Breathing System for Pediatric Anesthesia

The purpose of this study was to compare the Jackson-Rees circuit with the pediatric circle and MERA F breathing system (MERA F system) for pediatric anesthesia from the viewpoint of work of breathing (WOB). Twenty-three children (2-10 yr old) were studied during spontaneous breathing under endotracheal anesthesia with 4 L/min nitrous oxide, 2 L/min oxygen, and 1% end-tidal concentration of sevoflurane. WOB, inspiratory and expiratory airway resistance, dynamic compliance (CDYN), pressure time product (PTP), and arterial blood gasses were measured in the three circuits. The inspiratory WOB was estimated directly by measuring the esophageal pressure-volume loop using the Campbell technique. In a laboratory study, we measured the compliances of the Jackson-Rees circuit, the pediatric circle, the MERA F system, and the adult circuit. WOB differed among the three circuits (MERA F system > pediatric circle > Jackson-Rees circuit). Inspiratory and expiratory resistances, and arterial carbon dioxide tension in the Jackson-Rees circuit were significantly lower than those of both the pediatric circle and MERA F system. The CDYN and PTP in the MERA F system were significantly higher than those in both the Jackson-Rees circuit and the pediatric circle. The MERA F system had significantly higher compliance than the Jackson-Rees circuit and pediatric circle. It is concluded that the Jackson-Rees circuit is most efficient, the pediatric circle is intermediate, and the MERA F system is the least efficient from the viewpoint of WOB during spontaneous breathing for pediatric anesthesia. (Anesth Analg 1996;83:488-92)

Volume-Controlled Ventilation Is Made Possible in Infants by Using Compliant Breathing Circuits with Large Compression Volume

We studied the weight dependency of set tidal volume (VTset) during volume-controlled ventilation of 80 infants (ASA physical status I-IV, 0.7-20 kg), including prematures, neonates, and exprematures, who were anesthetized for major and minor surgery, including abdominal, thoracic, and neurosurgical procedures. After neuromuscular blockade and endotracheal intubation, infant's lungs were ventilated with an Ohmeda 7800 volume-limited ventilator and either a pediatric or adult circle breathing system (PC or AC) or a Bain circuit (Ba) and a pediatric- or adult-sized bellows (PB or AB). Except for larger and older infants in the ACAB group, body weight, age, peak inspiratory pressure (PIP), ETCO2, and SPO2 did not differ among groups. Compression volume loss was large in the five circuits tested. We found that VTset/kg varied with weight in a curvilinear relationship where y represents volume added and x represents PIP (y = 175.02x-0.87; r2 - 0.87), whereby VTset is approximately 150-200 mL/kg for a 1-kg infant and approximately 25 mL/kg for infants > or = 10 kg. Ventilation was adequate in each infant, except for one with extremely poor pulmonary compliance. We conclude that large compression volumes associated with compliant breathing systems make possible the use of volume-controlled ventilators in small infants.

Respiratory Frequency and Artifact Affect the Capnographic Baseline in Infants

We sought to determine the effect of rebreathing on the capnographic waveform baseline. In anesthetized infants, we studied the effect of respiratory frequency (f) and breathing circuit type (Bain, n = 6, and pediatric circle, n = 4) on capnography of respiratory gas aspirated from the circuit for mass spectrometry (PCO2asp) and flowing through an infrared analyzer (PCO2f-t). As f increased, measured values of PiCO2asp and PiCO2f-t increased in both Bain and circle groups, with the exception of PiCO2f-t values that remained zero in the circle group. PETCO2 decreased as f increased in the circle groups, but remained constant in the Bain groups. These data suggest that artifact, most likely due to parabolic distortion of CO2 plugs traversing long sampling catheters, makes up a significant percentage (8%-36%) of the aspiration capnographic baseline elevation depending on f and breathing circuit type. Despite increases in PiCO2 as f increased, PETCO2 does not increase in Bain circuits due primarily to an increase in minute ventilation (Ve) that offsets the increase in the PiCO2 to provide balance in the CO2 mass relationship (PETCO2 approximately VCO2/Ve+PiCO2). These findings are useful in the correct interpretation of elevated capnographic baseline in infants.

The “Educated Hand” Can Anesthesiologists Assess Changes in Neonatal Pulmonary Compliance Manually

To determine whether anesthesiologists can manually detect significant changes in pulmonary compliance in neonates using an "educated hand," the authors tested whether clinicians could detect clamping of an endotracheal tube connecting a neonatal lung model to one of three anesthesia breathing circuits. The test lungs corresponded to the lung of a full-term neonate (large lung) or a premature neonate (small lung), and the circuits were a disposable Mapleson D and a disposable pediatric circle system with and without a humidifier. Clinicians having four levels of expertise (inexperienced anesthesia residents, experienced anesthesia residents, faculty not specializing in pediatric anesthesia, and specialized pediatric anesthesia faculty) were permitted to choose fresh gas flows, ventilatory pattern, and rate. After an acclimation period, the endotracheal tube connecting the test lung to the circuit was occluded once for 30 s. Clinicians were credited with a successful detection if they reported the occlusion within 15 s and had fewer than one false positive per minute. With the large lung model, only 4 of 24 clinicians detected occlusion with the Mapleson D circuit; similar results were obtained with the other circuits. With the small lung model, the only successful detection occurred with the Mapleson D circuit. Success at detecting occlusion was similarly low for clinicians with different levels of expertise. The authors conclude that the commonly held belief that the "educated hand" permits clinicians to detect subtle changes in pulmonary compliance in neonates during anesthesia (necessitating manual rather than mechanical ventilation) is not true.

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.

Assessment of Spontaneous Ventilation in Anesthetized Children with Use of a Pediatric Circle or a Jackson-Rees System

To compare respiratory workloads, inspiratory efforts were evaluated in 11 children anesthetized with halothane while breathing through a pediatric circle or a Jackson-Rees system. All underwent urogenital surgery and received caudal analgesia after tracheal intubation. Anesthesia was maintained with O2/air at an end-tidal halothane concentration of 0.8%. A pediatric circle system at a fresh gas flow (FGF) of 0.5 and 1.5 x min ventilation (VE) (C0.5 and C1.5, respectively) and a Jackson-Rees system at FGF of 1.5 and 3.0 x VE (JR1.5 and JR3.0, respectively) were used in each patient in a random order. Tidal volume (VT), mean inspiratory flow (VT divided by the duration of inspiration TI, VT/TI), and the initial fast slopes of the airway occlusion pressure phase (delta P degrees/delta t FAST) were significantly lower (P less than 0.05) with the Jackson-Rees than with the circle system, indicating greater impedence to spontaneous breathing with the Jackson-Rees system. The Jackson-Rees system also required a greater peak transpulmonary pressure (PtpMAXe) than did the circle system to achieve the same peak expiratory flows (VMAXe, P less than 0.05), again suggesting an increased resistance with the Jackson-Rees system. These results are most likely explained by the difference in elastic loads (two to three times more with the Jackson-Rees systems) between the two systems. The pediatric circle system appears to be a reliable alternative to the Jackson-Rees system.

Deleading houses. Dangers in the dust.

The report of Amitai et al 1 in this issue dealing with the intensification of lead exposure in children whose homes were being deleaded is timely and sobering. While this kind of occurrence has received little attention in pediatric circles, it is not surprising that it can happen. A number of distressing reports have appeared describing intense lead exposure among adults who were stripping, sanding, or burning off lead-containing paint from houses and bridges. The brisk and marked elevation of blood lead and erythrocyte protoporphyrin levels in these patients suggests that the dosage of lead was high and absorption rapid. See also p 758. The means by which this exposure takes place is worthy of comment. Traditional dictum is that children get lead poisoning by eating paint chips. But do adult deleaders eat chips while they perform this unpleasant work? Most now wear masks or respirators. It is the dust generated

Wasted ventilation measured in vitro with eight anesthetic circuits with and without inline humidification.

Compression of gases (Boyle's law) and circuit compliance are major determinants of anesthesia circuit function. The materials of which circuits are constructed and the use of heated humidifiers may result in clinically important variations in delivered minute ventilation (VE) secondary to variations in compression volume. We examined eight anesthetic circuits both with and without a heated humidifier in an in vitro setting. Compression volume was determined with a large calibrated syringe. Circuit efficiency was determined by measuring VE at multiple peak inflation pressures (PIP) while using a pediatric ventilator with fixed VE, respiratory rate, fresh gas flow, and I/E ratio. As expected, both compression volume and delivered VE highly correlated with the type of circuit and the pressure at which it was examined (P less than 0.001). Mapleson D circuits had the lowest compression volume and were the most efficient circuits (P less than 0.0001). Pediatric circle systems were intermediate and adult circle systems had the largest compression volume and were the least efficient. Humidifiers uniformly increased compression volume. The following conclusions were drawn: 1) the anesthetic circuit, its material, and the pressure at which it operates are important determinants of circuit function; 2) humidifiers increase compression volume; 3) Mapleson D circuits had the lowest compression volume and therefore were the most efficient; 4) highly compliant adult circuits may result in compression volume losses that exceed the tidal volume of a pediatric ventilator; 5) humidifiers with low volume and rigid tubing should have the least effect on minute ventilation; and 6) highly compliant adult circuits when used in the care of infants and small children must be used with caution.

A high-humidity circle system for infants and children.

A scaled-down version of a modified adult circle system capable of increasing normal humidity output 300% was constructed for pediatric use. The moisture content of the gases leaving the system was tested and found to be superior to that of any pediatric circle system commercially available that does not incorporate an electrically heated water vaporizer.

Humidity output of the Columbia pediatric circle.

Humidity output of the Columbia pediatric circle.

Use of the Columbia pediatric circle valve for respiratory studies in the neonate.

Use of the Columbia pediatric circle valve for respiratory studies in the neonate.

Dynamics of Development: Euthenic Pediatrics

In recent years much discussion has developed in pediatric circles relative to the pediatrician's role in the broad field of child health. There is a consenses that pediatricians should be broadly educated in the development of later behavioristic problems, even into the adolescent years—in truth a position of eminence in the family constellation. With therapeutics of infectious diseases well documented and immunization procedures well stabilized, his abilities can be directed to the broad area of normal and abnormal sociomedical problems.