Lung protective ventilation during pulmonary resection in children: a prospective,single-centre,randomised controlled trial

Background

Perioperative ventilatory strategies for lung protection in children are underexplored. This study evaluated the effects of lung protective ventilation (LPV) on postoperative clinical outcomes in children requiring one-lung ventilation (OLV) for pulmonary resection.

Recruitment and PEEP level influences long‐time aeration in saline‐lavaged piglets: an experimental model

Objectives: To evaluate aeration/ventilation in saline‐lavaged piglets during a 3‐h follow‐up after a recruitment maneuver (RM)/PEEP titration compared with PEEP 10 cmH₂O without a RM. Background: Lung recruitment and PEEP titration are used to find a PEEP preventing repetitive opening/collapsing of lung. Methods: Twenty‐one lung‐lavaged piglets, mean age 7 weeks and mean weight 10 kg; a RM‐group and a PEEP10‐group, were ventilated at PEEP 5 cmH₂O (baseline) followed by zero PEEP ventilation. In the RM‐group, tidal elimination of CO₂ and dynamic compliance (Cdyn) guided recruitment and PEEP titration, respectively. A final 3‐h ventilation followed using PEEP 2 cmH₂O above the first decline of Cdyn and end‐inspiratory pressure (EIP) for a target tidal volume (V_T) of 10 ml·kg^?1. In the PEEP10‐group, PEEP 10 cmH₂O without a RM was used during the final 3‐h ventilation. CT scans and blood gases were repeated every 30 min. Airway pressures, Cdyn and hemodynamics were continuously recorded. Results: Aeration improved without differences between groups. The RM‐group PEEP level of 10 ± 0.6 cmH₂O did not differ from the PEEP10‐group. Compared to baseline EIP was lower in the RM‐group after 3‐h ventilation. In both groups, driving pressure (DP) was lower and Cdyn higher than baseline. In the RM‐group, final EIP and DP were lower and Cdyn higher than in the PEEP10‐group. Conclusions: Both RM/PEEP titration and PEEP elevation resulted in improved aeration without differences between groups at the end point. Lung aeration was achieved at lower EIP and DP and higher Cdyn in the RM‐group than in the PEEP10‐group.     

Effects of desflurane and propofol on arterial oxygenation during one-lung ventilation in the pig

Background: Desflurane depresses hypoxic pulmonary vasoconstriction (HPV) in vitro. During one-lung ventilation (OLV), HPV may reduce venous admixture and ameliorate the decrease in arterial O₂ tension by diverting blood from the non-ventilated to the ventilated lung. Accordingly, this study compares the effects of desflurane with those of propofol on oxygenation during two-lung (TLV) and OLV in vivo. Methods: Ten pigs (25–30 kg) were premedicated (flunitrazepam 0.4 mg/kg im), anaesthetized (induction: propofol 2 mg/kg iv; maintenance: N₂O/O₂ 50%/50%, desflurane 3%, propofol 50 μg kg^?1 min^?1, and vecuronium 0.2 mg kg^?1 h^?1 iv), orally intubated and mechanically ventilated. Femoral arterial and thermodilution pulmonary artery catheters were placed, and the orotracheal tube was replaced by a left-sided 28-Ch double-lumen tube (DLT) via tracheotomy. After DLT placement, N₂O and propofol were discontinued, FiO₂ was increased to 0.85, and anaesthesia continued randomly with either desflurane (1 MAC) or propofol 200 μg kg^?1 min^?1. Using a cross-over design, in each animal the effects of a), changing from TLV to OLV (left lung) during both desflurane and propofol and b), the effects of changing between the two anaesthetics during OLV were studied. Results: When changing from TLV to OLV, PaO₂ decreased more (P<0.05) during desflurane (mean 75%) than during propofol (mean 60%). Changing between desflurane and propofol during OLV resulted in small but consistent (P<0.05) increases in PaO₂ (mean 15%) during propofol. Conclusion: Consistent with in vitro results on HPV, 1 MAC desflurane impaired in vivo oxygenation during OLV more than did propofol.     

胸科手术中单肺通气期间不同通气方式的比较

目的 观察胸科手术病人麻醉中单肺通气（ＯＬＶ）期间不同通气方式的效果。方法 １０例择期胸科手术成年病人,ＡＳＡⅠ～Ⅱ级,在ＯＬＶ期间首先采用全潮气量（１０ｍｌ／ｋｇ）不加ＰＥＥＰ,随后采用半潮气量（５ｍｌ／ｋｇ）同时施加７ｃｍＨ２Ｏ ＰＥＥＰ两种通气方式,保持每分通气量不变。在开胸后ＯＬＶ前,ＯＬＶ时采用敏种通气方式后３０ｍｉｎ,以及恢复双肺通气（ＴＬＶ）后３０ｍｉｎ分别进行血气分析,同时监测气道     

Monitoring of vecuronium-induced neuromuscular blockade during one-lung ventilation

Purpose  We investigated the monitoring of neuromuscular blockade caused by vecuronium in patients receiving one-lung ventilation (OLV) anesthesia for lung surgery. Methods  Eighteen adult patients requiring OLV for lung surgery (OLV group) and 18 undergoing two-lung ventilation (TLV) for colon surgery (control group) were enrolled in this study. In the two groups, anesthesia was maintained with sevoflurane, fentanyl, and epidural lidocaine. Time from vecuronium 0.1 mg·kg⁻¹ to the onset of neuromuscular blockade; times to the return of T1, T2, T3, or T4 (the first, second, third, or fourth response of the train-of-four [TOF]); and recovery of T1/control or TOF ratio (T4/T1) were compared between the two groups. Results  Time to the onset of neuromuscular blockade in the OLV group was similar to that in the control group (289 ± 74 vs 270 ± 85 s [mean ± SD]; P = 0.482). Times from vecuronium to the return of T1, T2, T3, or T4 in the OLV group did not significantly differ from those in the control group (21.9 ± 7.0 vs 25.8 ± 6.7 min for T1; P = 0.099). T1/control in the OLV group was significantly higher than that in the control group 50-120 min after vecuronium (P < 0.05). The TOF ratio did not differ significantly between the two groups. Conclusion  During OLV for lung surgery, recovery of T1/control is accelerated in anesthetized patients receiving vecuronium.     

Single-lung ventilation with carbon dioxide hemipneumothorax: hemodynamic and respiratory effects in piglets

Objectives: Video‐assisted thoracoscopic surgery (VATS) has become a standard procedure in pediatric surgery. To facilitate surgical access, the dependent lung has to collapse using intrathoracic carbon dioxide insufflation and/or single‐lung ventilation. These procedures can induce hemodynamic deteriorations in adults. The potential impacts of single‐lung ventilation in combination with capnothorax on hemodynamics in infants have never been studied before. Aim: We conducted a randomized experimental study focusing on hemodynamic and respiratory changes during single‐lung ventilation with or without capnothorax in a pediatric animal model. Methods: Twelve piglets were randomly assigned to receive single‐lung ventilation with (SLV‐CO₂) or without (SLV) capnothorax with an insufflation pressure of 5 mmHg for a period of two hours. Before, during, and after single‐lung ventilation, hemodynamic and respiratory parameters were measured. Results: Although mean arterial pressure remained stable during the course of the study and no critical incidents were monitored, cardiac index (CI) decreased significantly with SLV‐CO₂ (baseline 3.6 ± 1.6 l·min^?1·m^?2 vs 2.9 ± 1.1 l·min^?1·m^?2 at 120 min, P < 0.05). Furthermore, global end‐diastolic volume and intrathoracic blood volume (ITBV) decreased as well significantly with SLV‐CO₂, causing a significant between‐group difference in ITBV (P < 0.05). Conclusions: Despite a decrease in CI and preload parameters, the combination of single‐lung ventilation and low‐pressure capnothorax was well tolerated in piglets and could justify further clinical studies to be performed in infants and children focusing on hemodynamic and respiratory changes during VATS.     

Low dose methylprednisolone prophylaxis to reduce inflammation during one-lung ventilation

Background: The specific aim of this study was to examine the efficacy of a low dose of methylprednisolone in minimizing inflammatory response in juvenile piglets when given 45–60 min prior to onset of one‐lung ventilation. Methods: Twenty piglets aged 3 weeks were assigned to either the control group (n = 10) or methylprednisolone group (n = 10). The animals were anesthetized and after 30 min of ventilation, they had their left lung blocked. Ventilation was continued via right lung for 3 h. The left lung was then unblocked. Following another 30 min of bilateral ventilation, the animals were euthanized and both lungs were harvested. The methylprednisolone group had a single dose (2 mg·kg^?1) of methylprednisolone given i.v. 45–60 min prior to onset of one‐lung ventilation. Physiological parameters (PaO₂, resistance, and compliance) and markers of inflammation (tumor necrosis factor [TNF]‐α, interleukin [IL]‐1β, IL‐6, and IL‐8) were measured at baseline and every 30 min thereafter. Lung tissue homogenates from both collapsed and ventilated lungs were analyzed for TNF‐α, IL‐1β, IL‐6, and IL‐8. Results: The methylprednisolone group had higher partial pressure of oxygen (P = 0.01), lower plasma levels of TNF‐α (P = 0.03) and IL‐6 (P = 0.001) when compared with control group. Lung tissue homogenate in the methylprednisolone group had lower levels of TNF‐α (P < 0.05), IL‐1β (P < 0.05), and IL‐8 (P < 0.05) in both the collapsed and the ventilated lungs. Conclusions: In a piglet model of one‐lung ventilation, use of prophylactic methylprednisolone prior to collapse of the lung improves lung function and decreases systemic pro‐inflammatory response. In addition, in the piglets who received methylprednisolone, there were reduced levels of inflammatory mediators in both the collapsed and ventilated lungs.     

Effects of tidal volume and PEEP on arterial blood gases and pulmonary mechanics during one-lung ventilation

Purpose

The main problem of one-lung ventilation (OLV) is hypoxemia. The use of a high tidal volume for preventing hypoxemia during OLV is controversial. We compared the effects of a high tidal volume versus a low tidal volume with or without PEEP on arterial oxygen tension (PaO₂) and pulmonary mechanics during OLV.

Methods

Sixty patients (age range, 16–65?years; ASA I, II) who underwent wedge resection with video-assisted thoracostomy during OLV were assigned to three groups: group I received a high tidal volume (10?ml/kg) (n?=?20), group II received a low tidal volume (6?ml/kg) (n?=?20), and group III received a low tidal volume (6?ml/kg) with PEEP (5?cmH₂O) (n?=?20). Patient hemodynamics, pulmonary mechanics, and arterial blood gases were measured before (T₀) OLV and 5 (T₁), 15 (T₂), 30 (T₃), and 45?min (T₄) after OLV.

Results

The PaO₂/FiO₂ ratios of group II and III were significantly decreased and the incidence of hypoxemia was significantly higher in groups II and III than in group I (P?Conclusion During OLV, mechanical ventilation with a low tidal volume with or without PEEP increased hypoxemia as compared to that when performing OLV with a high tidal volume.     

Hyperventilation versus standard ventilation for infants in postoperative care for congenital heart defects with pulmonary hypertension

Purpose  In infants undergoing surgery for cardiac defects with left-to-right shunt, a hyperventilation strategy has been applied to prevent pulmonary hypertensive crisis (PHC). Hyperventilation with a large tidal volume and/or higher airway pressure, however, may be detrimental to the lung. This randomized study compared the effects of hyperventilation versus standard ventilation. Methods  We enrolled 22 infants with a preoperative pulmonary-to-systemic blood pressure ratio of more than 0.7. Hyperventilation, with a tidal volume of 10–12 ml·kg⁻¹ to keep between 30 and 35 mmHg, was randomly applied in 11 patients for 16 h or more. The other 11 patients were randomly assigned to standard ventilation, with a 6- to 8- ml·kg⁻¹ tidal volume. Results  The peak inspiratory pressure was higher (20 ± 3 vs 18 ± 2 cmH₂O; P = 0.018), and (34 ± 5 vs 42 ± 7 mmHg; P = 0.003) and positive end-expiratory pressure (3 ± 0 vs 5 ± 0; P < 0.0001) were significantly lower in the hyperventilation than in the standard ventilation group. The /inspiratory fraction of oxygen ratio decreased from 244 ± 160 mmHg at the onset of postoperative ventilation, to 177 ± 96 mmHg at 24 h (P = 0.038) in the hyperventilation group, versus a decrease from 240 ± 89 to 220 ± 97 mmHg in the standard ventilation group not significant (NS). Serum interleukin (IL)-6 level, measured at 24 h postoperatively, was significantly lower (P = 0.02) in the standard ventilation than in the hyperventilation group, suggesting an attenuated postoperative systemic inflammatory response. A single patient in each group developed PHC. Conclusion  Hyperventilation may cause lung injury and systemic inflammation in infants with pulmonary hypertension undergoing corrective heart surgery. T. Umenai and N. Shime contributed equally to this study.     

Cardiovascular responses to high-frequency oscillatory ventilation during acute lung injury in sheep

Purpose The present study was designed to evaluate pulmonary and systemic hemodynamics and blood gas changes on switching from conventional mechanical ventilation (CMV) to high-frequency oscillatory ventilation (HFOV) in a large animal model of acute lung injury. Methods Eleven anesthetised sheep chronically instrumented with vascular monitoring were prepared. Animals received oleic acid (0.08 ml·kg⁻¹) intravenously and were ventilated for 4 h h after the administration of oleic acid. The animals were then randomized into the two following different ventilation modes: CMV (tidal volume [V_T], 6 ml·kg⁻¹; respiratory rate [RR], 25 · min⁻¹) with positive end-expiratory pressure (PEEP) of 12 cmH₂O; or CMV under the same settings without PEEP. HFOV was then switched. The setting of mean airway pressure with a fixed stroke volume was changed between 25, 18, and 12 cmH₂O every 20 min. Mean pulmonary artery pressure, pulmonary artery occlusive pressure (Paop), left atrium pressure, systemic arterial pressure, cardiac output (CO), and blood gas composition under each setting were measured before and after HFOV. Results Switching to HFOV, from without PEEP, resulted in significant increases in Paop and PaO2 and a decrease in CO at higher (25, 18 cmH₂O) mean airway pressure. However, when changed from low V_T and PEEP, HFOV produced further improvements in oxygenation without any deterioration of cardiovascular depression. Thus, switching to HFOV from CMV with low V_T and high PEEP may have little influence on pulmonary or systemic hemodynamics in acute lung injury. Conclusion We conclude that hemodynamic responses are dependent on the predefined setting of PEEP during CMV, and on applied mean airway pressure during HFOV.     

Effect of peak inspiratory flow on gas exchange, pulmonary mechanics, and lung histology in rabbits with injured lungs

Purpose The aim of this study was to evaluate, using a rabbit model, the little-known effect of different levels of peak inspiratory flow on acutely injured lungs. Methods Fourteen male rabbits (body weight, 2711 ± 146 g) were anesthetized and their lungs were injured by alveolar overstretch with mechanical ventilation until Pa_O2 was reduced below 300 mmHg. Injured animals were randomly assigned to: the P group—to receive pressure-regulated volume-control ventilation (PRVCV; n = 7); and the V group—to receive volume-control ventilation (VCV; n = 7). Other ventilator settings were: fraction of inspired oxygen (FI_O2), 1.0; tidal volume, 20 ml·kg⁻¹; positive end-expiratory pressure (PEEP) 5 cmH₂O; and respiratory rate, 20 min⁻¹. The animals were thus ventilated for 4 h. Throughout the protocol, ventilatory parameters and blood gas were measured every 30 min. After the protocol, the lung wet-to-dry ratio and histological lung injury score were evaluated in the excised lungs. Results Throughout the protocol, peak inspiratory flow and mean inspiratory flow values in the P group were significantly higher than those in the V group (26.7 ± 5.0 l·min⁻¹ vs 1.2 ± 0.2 l·min⁻¹, and 4.3 ± 0.3 l·min⁻¹ vs 1.1 ± 0.1 l·min⁻¹; P < 0.05). The wet-to-dry ratio in the P group was also significantly higher than that in the V group (7.7 ± 0.9 vs 6.3 ± 0.5; P < 0.05). More animals in the P group than in the V group had end-of-protocol Pa_O2/FI_O2 ratios below 200 mmHg (43% vs 0%; P = 0.06). Conclusion In rabbits with injured lungs, high peak inspiratory flow with high tidal volume (V_T) reduces the Pa_O2/FI_O2 ratio and increases the lung wet-to-dry ratio.     

Auswirkungen von Dopexamin Transpulmonales Shuntvolumen bei thorax- chirurgischen Eingriffen mit Ein-Lungen-Beatmung

Objective: To study the influence of dopexamine on pulmonary shunt and hypoxic pulmonary vasoconstriction during major thoracic surgery with one-lung ventilation (OLV). Design: Prospective, randomised, placebo-controlled study. Setting: University hospital. Patients: Twenty adult patients undergoing elective pulmonary resection. Anaesthesia: General anaesthesia was performed using propofol, fentanyl, N₂O and vecuronium.Volume-controlled ventilation was performed to maintain normocapnia over the whole investigation period. During OLV, the tidal volume was reduced and the respiratory rate was increased to avoid a peak airway pressure exceeding 40 cm H₂O. Furthermore the FiO₂ was increased to 1,0 and the external PEEP was removed during OLV. Interventions: The patients received either dopexamine at 2 µg/kg/min (group A, n=10) or 0,9% saline as control (group B, n=10) after assessing the baseline values. Measurement and results: The following cardiorespiratory variables were recorded: Heart rate, mean arterial pressure and mean pulmonary arterial pressure. Cardiac output was measured by thermodilution using a continuous cardiac output thermodilution catheter. Arterial and mixed venous blood gas analysis were measured from simultaneously drawn samples. Cardiac index (CI), systemic vascular resistance index, pulmonary vascular resistance index, oxygen delivery index (DO₂I), oxygen consumption index and the venous admixture were calculated using standard formula. Furthermore, pressure-flow-curves were constructed to analyse flow independent changes in the pulmonary vascular resistance. Data were recorded at the following times: After induction of anaesthesia in stable haemodynamics during two-lung ventilation (baseline values, T0), intraoperatively during one-lung ventilation (T1) and postoperatively after re-establishing two-lung ventilation (T2). Patients characteristics, data from the preoperative lung function testing and surgical procedures did not differ significantly between the groups. CI increased in the dopexamine group from 2,5±1,2 l·min^?1·m^?2 (T0) to 3,6±0,9 l·min^?1·m^?2 (T1) and 4,0±1,3 l·min^?1· m^?2 (T2). The course of the intrapulmonary right-to-left shunting did not differ between the groups. In the dopexamine-treated group the DO₂I increased from 430±143 ml·min·m^?2 (T0) to 652±255 ml·min·m^?2 (T1) and 653±207 ml·min·m^?2 (T2). Regarding the pressure-flow-curves there was no difference during OLV between the two groups indicating no major blocking effect of dopexamine on hypoxic pulmonary vasoconstriction. Conclusion: It is concluded that dopexamine can be used to improve haemodynamics and oxygen delivery during thoracic surgery without increasing venous admixture during one-lung ventilation.     

How do COPD and healthy-lung patients tolerate the reduced volume ventilation strategy during OLV ventilation

Background: Although a strategy of tidal volume (V_t) reduction during the one‐lung ventilation (OLV) period is advised in thoracic surgery, the influence of the pre‐operative respiratory status on the tolerance of this strategy remains unknown. Therefore, the aim of this study was to compare the pulmonary function between chronic obstructive pulmonary disease (COPD) and healthy‐lung patients during the operative and the post‐operative period. Methods: Forty‐eight patients undergoing a planned lobectomy for cancer and presenting either a healthy lung function (n=24) or a moderate COPD stage (n=24) were ventilated without external positive end‐expiratory pressure (PEEP) and received 9 ml/kg V_t during the two‐lung ventilation (TLV) period, secondary reduced to 6 ml/kg during the OLV period. Lung function was assessed by peroperative gas exchange, venous admixture, respiratory mechanical parameters and post‐operative spirometric measurements. Results: Although the PaO₂ was superior in the healthy‐lung group during the TLV, once the OLV was established, no difference was observed between the two groups. Moreover, the PaO₂/FiO₂ was proportionally more impaired in the healthy‐lung group compared with the COPD group (50 ± 13 vs. 72 ± 19% of the baseline values after exclusion and 32 ± 15 vs. 51 ± 25% after the thoracotomy, P<0.05 for each) as well as the venous admixture. In the post‐operative period, a higher decrease was observed in the healthy‐lung group for the forced vital capacity and the forced expiratory volume. Conclusions: Reducing V_t to 6 ml/kg without the adjunction of external PEEP during OLV is associated with better preservation of lung function in the case of moderate COPD than in the case of healthy‐lung status.     

Flexion compromises ventilation with the laryngeal tube suction II in children

Background: There are insufficient data as to the influence of the head and neck flexion, extension, and rotation on the ventilation with laryngeal tube suction II^® (LTS II). The purpose of this study was to investigate the influence of the head and neck position on oropharyngeal sealing pressure (primary outcome) and ventilation score (secondary outcome) during ventilation with the LTS II in children. Methods: We studied 33 children scheduled for elective surgery. Oropharyngeal sealing pressure and ventilation score were measured with the head and neck in a neutral position, flexed, extended and rotated to the right. The ventilation score was scored from 0 to 3 based on three items (no leakage with an airway pressure of 15 cmH₂O, bilateral chest excursion, and a square wave capnogram; each item scored 0 or 1 point). Peak inspiratory pressure (PIP) at a tidal volume of 10 ml·kg^?1 and fiberoptic laryngeal views were also assessed in each position. Results: Although the sealing pressure was lower in the extended position [22 (8) cmH₂O] than that in the neutral position [25 (7) cmH₂O], there was no significant leakage during ventilation with a tidal volume of 10 ml·kg^?1. In the neutral, extended and rotated positions, the median ventilation scores were better (3 point respectively) than that with the head and neck flexed (1 point). PIP was decreased with the head and neck extended or rotated but was significantly increased in flexion position. During fibreoptic examination, the vocal cords were more easily seen in extension and right rotation, compared with the neutral position and flexion. Conclusions: Although oropharyngeal sealing pressure is decreased with the head and neck extended, effective ventilation with LTS II can be performed like in the neutral position or the rotated position. While the sealing pressure is maintained with the head and neck flexed, flexion compromises the ventilation with LTS II in children.     

One-lung ventilation with high tidal volumes and zero positive end-expiratory pressure is injurious in the isolated rabbit lung model

We tested the hypothesis that one-lung ventilation (OLV) with high tidal volumes (VT) and zero positive end-expiratory pressure (PEEP) may lead to ventilator-induced lung injury. In an isolated, perfused rabbit lung model, VT and PEEP were set to avoid lung collapse and overdistension in both lungs, resulting in a straight pressure-time (P-vs-t) curve during constant flow. Animals were randomized to (a) nonprotective OLV (left lung) (n = 6), with VT values as high as before randomization and zero PEEP; (b) protective OLV (left lung) (n = 6), with 50% reduction of VT and maintenance of PEEP as before randomization; and (c) control group (n = 6), with ventilation of two lungs as before randomization. The nonprotective OLV was associated with significantly smaller degrees of collapse and overdistension in the ventilated lung (P < 0.001). Peak inspiratory pressure values were higher in the nonprotective OLV group (P < 0.001) and increased progressively throughout the observation period (P < 0.01). The mean pulmonary artery pressure and lung weight gain values, as well as the concentration of thromboxane B(2), were comparatively higher in the nonprotective OLV group (P < 0.05). A ventilatory strategy with VT values as high as those used in the clinical setting and zero PEEP leads to ventilator-induced lung injury in this model of OLV, but this can be minimized with VT and PEEP values set to avoid lung overdistension and collapse. IMPLICATIONS: One-lung ventilation with high tidal volumes and zero positive end-expiratory pressure (PEEP) is injurious in the isolated rabbit lung model. A ventilatory strategy with tidal volumes and PEEP set to avoid lung overdistension and collapse minimizes lung injury during one-lung ventilation in this model.     

Automatic jet ventilation in children anaesthetized by the T-piece circuit

Investigation was carried out in ten children aged between one month and six years, who were anaesthetized by the T-piece circuit. The volume of the reservoir tubing of the T-piece was 250 ml. Ventilation was controlled automatically by oxygen jets which were delivered via an injector attached to the reservoir tubing. The oxygen jets were regulated by an electronically-controlled solenoid valve. The children were ventilated by a tidal volume about 12 ml±kg^?1 at a rate of 12-20 per min depending on their age, while the FGF varied between 3 and 6 l min^?1 depending on their body weight. The resulting FIO₂ ranged between 0.32 and 0.34 which was expected from the oxygen:nitrous oxide mixture (1:2), denoting no mixing of the oxygen jets with the anaesthetic mixture. The PA_co2 was ventilation-dependent, and ranged between 4±6-5±3 kPa (35-41 mmHg). The results suggest that automatic jet ventilation facilitates controlled ventilation in children anaesthetized by the T-piece circuit, while maintaining the original simplicity of the T-piece.;     

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery (PROVAR): a randomised controlled trial

Background

Experimental studies showed that controlled variable ventilation (CVV) yielded better pulmonary function compared to non-variable ventilation (CNV) in injured lungs. We hypothesized that CVV improves intraoperative and postoperative respiratory function in patients undergoing open abdominal surgery.

Physiological effects of a lung-recruiting strategy applied during one-lung ventilation

Background: One‐lung ventilation (OLV) affects respiratory mechanics and ventilation/perfusion matching, reducing functional residual capacity of the ventilated lung. While the application of a lung‐recruiting manoeuvre (RM) on the ventilated lung has been shown to improve oxygenation, data regarding the impact of RM on respiratory mechanics are not available. Methods: Thirteen patients undergoing lung resection in lateral decubitus were studied. During OLV, a lung‐recruiting strategy consisting in a RM lasting 1 min followed by the application of positive end‐expiratory pressure 5 cmH₂O was applied to the ventilated lung. Haemodynamics, gas exchange and respiratory mechanics parameters were recorded on two‐lung ventilation (TLV_baseline), OLV before and 20 min after the RM (OLV_pre‐RM, OLV_post‐RM, respectively) and TLV_end. Haemodynamics parameters were also recorded during the RM. Results: The PaO₂/FiO₂ ratio was 358±126 on TLV_baseline; it decreased to 235±113 on OLV_pre‐RM (P<0.01) increased to 351±120 on OLV_post‐RM (P<0.01 vs. OLV_pre‐RM), and remain stable thereafter. During the RM, CI decreased from 3.04±0.7 l/m² OLV_pre‐RM to 2.4±0.6 l/m² (P<0.05), and returned to baseline on OLV_post‐RM (3.1±0.7 l/m², NS vs. OLV_pre‐RM). The RM resulted in alveolar recruitment and caused a significant decrease in static elastance of the dependent lung (16.6±8.9 cmH₂O/ml OLV_post‐RM vs. 22.3±8.1 cmH₂O/ml OLV_pre‐RM) (P<0.01). Conclusions: During OLV in lateral decubitus for thoracic surgery, application to the dependent lung a recruiting strategy significantly recruits the dependent lung, improving arterial oxygenation and respiratory mechanics until the end of surgery. However, the transient haemodynamic derangement occurring during the RM should be taken into account.     

Measuring circulating blood volume in newborn infants using pulse dye densitometry and indocyanine green

Background: Circulating blood volume (BV) is an important, but often unconsidered, variable in newborn infants undergoing intensive care. The data on validation and repeatability of BV measurement are limited. Aim: To validate and test the repeatability of measuring BV in newborn infants using indocyanine green (ICG) and pulse dye densitometry (PDD). Methods: Validation– Paired measurements of BV were made using the fetal hemoglobin (HbF) dilution and the PDD method. Repeatability– The BV was measured twice at an interval of 30–40 min in a second group of infants. Results: Validation– Data from three of 13 infants studied were excluded because of probe dislodgement or ICG injection error. The median (range) birth weight of the 10 infants whose data were analyzed was 1032 g (740–2384 g) and seven (70%) were receiving either mechanical ventilation or nasal CPAP. The median BV measured by HbF dilution was 66.2 ml·kg^?1 (43.7–81.0 ml·kg^?1) and by the PDD method was 68.9 ml·kg^?1 (49.3–101.0 ml·kg^?1). The mean difference was 5.92 ml·kg^?1 (sd 17.33 ml·kg^?1). Repeatability– Twelve infants were studied and three excluded because of probe dislodgement/motion artifact or ICG injection error. The median weight of the nine infants whose data were analyzed was 1208 g (795–2600 g). The median (range) BV1 and BV2 were 70.5 ml·kg^?1 (53.1–160 ml·kg^?1) and 87.5 ml·kg^?1 (38.0–248.0 ml·kg^?1), respectively. Mean difference of the two BV estimates (BV1–BV2) was ?24.6 ml·kg^?1 (sd 33.3 ml·kg^?1) and coefficient of repeatability was 66.5 ml·kg^?1. Conclusion: Pulse dye densitometry can be used to measure BV in the newborn infant at the cotside but the repeatability measurements suggest that its use is limited.     

Changes in carbon dioxide tension and oxygen saturation during deep sedation for paediatric cardiac catheterization

The purpose of this observational study was to determine whether hypercarbia or oxygen desaturation occurred during our current regimens of deep sedation or general anaesthesia of infants and children undergoing cardiac catheterization. Data were gathered prospectively from 50 consecutive infants and children aged 4 months to 12 years undergoing cardiac catheterization. Several anaesthetists used the following regimens, which were not randomized: 1) propofol. 1.5–2.0 mg·kg^?1 and fentanyl 1 μg·kg^?1 IV over 2 min for induction, followed by propofol infusion of 100–150 μg·kg^?1·min^?1; 2) fentanyl 2–3 μg·kg^?1 and midazolam 0.1–0.2 mg·kg^?1 IV over 10–15 min; 3) ketamine 8 mg·kg^?1 IM, or 4) same as regimens 1 or 2, plus pancuronium, intubation and controlled ventilation. Regimens 1, 2, and 3 were associated with spontaneous ventilation through the natural airway. End-tidal carbon dioxide tension (Petco₂), Spo₂, and respiratory rate were monitored for 60 min. The three regimens employing spontaneous ventilation through the natural airway were associated with both statistically and clinically significant increases in Petco₂ and decreases in Spo₂. This raises the possibility that acute exacerbation of PAP and PVR may occur in pulmonary hypertensive patients. In contrast, Petco₂ and Spo₂ did not change significantly from baseline in the controlled ventilation group.