End-expiratory lung volume and ventilation distribution with different continuous positive airway pressure systems in volunteers

Background: Continuous positive airway pressure (CPAP) has been shown to improve oxygenation and a number of different CPAP systems are available. The aim of this study was to assess lung volume and ventilation distribution using three different CPAP techniques. Methods: A high‐flow CPAP system (HF‐CPAP), an ejector‐driven system (E‐CPAP) and CPAP using a Servo 300 ventilator (V‐CPAP) were randomly applied at 0, 5 and 10 cmH₂O in 14 volunteers. End‐expiratory lung volume (EELV) was measured by N₂ dilution at baseline; changes in EELV and tidal volume distribution were assessed by electric impedance tomography. Results: Higher end‐expiratory and mean airway pressures were found using the E‐CPAP vs. the HF‐CPAP and the V‐CPAP system (P<0.01). EELV increased markedly from baseline, 0 cmH₂O, with increased CPAP levels: 1110±380, 1620±520 and 1130±350 ml for HF‐, E‐ and V‐CPAP, respectively, at 10 cmH₂O. A larger fraction of the increase in EELV occurred for all systems in ventral compared with dorsal regions (P<0.01). In contrast, tidal ventilation was increasingly directed toward dorsal regions with increasing CPAP levels (P<0.01). The increase in EELV as well as the tidal volume redistribution were more pronounced with the E‐CPAP system as compared with both the HF‐CPAP and the V‐CPAP systems (P<0.05) at 10 cmH₂O. Conclusion: EELV increased more in ventral regions with increasing CPAP levels, independent of systems, leading to a redistribution of tidal ventilation toward dorsal regions. Different CPAP systems resulted in different airway pressure profiles, which may result in different lung volume expansion and tidal volume distribution.     

Impact of changes of positive end-expiratory pressure on functional residual capacity at low tidal volume ventilation during general anesthesia

Purpose

Several reports in the literature have described the effects of positive end-expiratory pressure (PEEP) level upon functional residual capacity (FRC) in ventilated patients during general anesthesia. This study compares FRC in mechanically low tidal volume ventilation with different PEEP levels during upper abdominal surgery.

Methods

Before induction of anesthesia (awake) for nine patients with upper abdominal surgery, a tight-seal facemask was applied with 2?cmH₂O pressure support ventilation and 100?% O₂ during FRC measurements conducted on patients in a supine position. After tracheal intubation, lungs were ventilated with bilevel airway pressure with a volume guarantee (7?ml/kg predicted body weight) and with an inspired oxygen fraction (FIO₂) of 0.4. PEEP levels of 0, 5, and 10?cmH₂O were used. Each level of 5 and 10?cmH₂O PEEP was maintained for 2?h. FRC was measured at each PEEP level.

Results

FRC awake was significantly higher than that at PEEP 0?cmH₂O (P?<?0.01). FRC at PEEP 0?cmH₂O was significantly lower than that at 10?cmH₂O (P?<?0.01). PaO₂/FIO₂ awake was significantly higher than that for PEEP 0?cmH₂O (P?<?0.01). PaO₂/FIO₂ at PEEP 0?cmH₂O was significantly lower than that for PEEP 5?cmH₂O or PEEP 10?cmH₂O (P?<?0.01). Furthermore, PEEP 0?cmH₂O, PEEP 5?cmH₂O after 2?h, and PEEP 10?cmH₂O after 2?h were correlated with FRC (R?=?0.671, P?<?0.01) and PaO₂/FIO₂ (R?=?0.642, P?<?0.01).

Conclusions

Results suggest that PEEP at 10?cmH₂O is necessary to maintain lung function if low tidal volume ventilation is used during upper abdominal surgery.     

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.     

Changes in ventilator settings and ventilation–induced lung injury in burn patients—A systematic review

ObjectiveVentilation strategies aiming at prevention of ventilator–induced lung injury (VILI), including low tidal volumes (V_T) and use of positive end–expiratory pressures (PEEP) are increasingly used in critically ill patients. It is uncertain whether ventilation practices changed in a similar way in burn patients. Our objective was to describe applied ventilator settings and their relation to development of VILI in burn patients.Data SourcesSystematic search of the literature in PubMed and EMBASE using MeSH, EMTREE terms and keywords referring to burn or inhalation injury and mechanical ventilation.Study selectionStudies reporting ventilator settings in adult or pediatric burn or inhalation injury patients receiving mechanical ventilation during the ICU stay.Data extractionTwo authors independently screened abstracts of identified studies for eligibility and performed data extraction.Data synthesisThe search identified 35 eligible studies. V_T declined from 14 ml/kg in studies performed before to around 8 ml/kg predicted body weight in studies performed after 2006. Low-PEEP levels (<10 cmH₂O) were reported in 70% of studies, with no changes over time. Peak inspiratory pressure (PIP) values above 35 cmH₂O were frequently reported. Nevertheless, 75% of the studies conducted in the last decade used limited maximum airway pressures (≤35 cmH₂O) compared to 45% of studies conducted prior to 2006. Occurrence of barotrauma, reported in 45% of the studies, ranged from 0 to 29%, and was more frequent in patients ventilated with higher compared to lower airway pressures.ConclusionThis systematic review shows noticeable trends of ventilatory management in burn patients that mirrors those in critically ill non-burn patients. Variability in available ventilator data precluded us from drawing firm conclusions on the association between ventilator settings and the occurrence of VILI in burn patients.     

Alveolar recruitment strategy and PEEP improve oxygenation,dynamic compliance of respiratory system and end‐expiratory lung volume in pediatric patients undergoing cardiac surgery for congenital heart disease

Objective: Optimizing alveolar recruitment by alveolar recruitment strategy (ARS) and maintaining lung volume with adequate positive end‐expiratory pressure (PEEP) allow preventing ventilator‐induced lung injury (VILI). Knowing that PEEP has its most beneficial effects when dynamic compliance of respiratory system (Crs) is maximized, we hypothesize that the use of 8 cm H₂O PEEP with ARS results in an increase in Crs and end‐expiratory lung volume (EELV) compared to 8 cm H₂O PEEP without ARS and to zero PEEP in pediatric patients undergoing cardiac surgery for congenital heart disease. Methods: Twenty consecutive children were studied. Three different ventilation strategies were applied to each patient in the following order: 0 cm H₂O PEEP, 8 cm H₂O PEEP without an ARS, and 8 cm H₂O PEEP with a standardized ARS. At the end of each ventilation strategy, Crs, EELV, and arterial blood gases were measured. Results: EELV, Crs, and P_aO₂/FiO₂ ratio changed significantly (P < 0.001) with the application of 8 cm H2O + ARS. Mean P_aCO₂– PETCO₂ difference between 0 PEEP and 8 cm H2O PEEP + ARS was also significant (P < 0.05). Conclusion: An alveolar recruitment strategy with relative high PEEP significantly improves Crs, oxygenation, P_aCO₂– PETCO₂ difference, and EELV in pediatric patients undergoing cardiac surgery for congenital heart disease.     

Surfactant alterations following donation after cardiac death donor lungs

The use of lungs from donation after cardiac death (DCD) donors is one of the strategies to increase the donor pool. The aim of this study was to assess the surfactant alterations in DCD donor lungs. Pigs were sacrificed and left untouched for 1 (DCD1), 2 (DCD2) and 3 (DCD3) h. Lungs were then topically cooled with saline for 1, 2 or 3 h to reach a total ischemic time of 4 h. Heart‐beating donors (HBD) served as control group. Bronchoalveolar lavage (BAL) samples were assessed for protein levels and surfactant function. Left lungs were prepared for ex‐vivo evaluation. Pulmonary vascular resistance (PVR), oxygenation, airway pressure (AWP) and wet‐to‐dry weight ratio were significantly different between HBD and DCD3 groups (P < 0.05). BAL protein levels were statistically higher in DCD3 compared with HBD group (P < 0.05). Surface tension and surface tension measured at minimal bubble diameter (adsorption) were lower in HBD compared with DCD groups (P < 0.05). Adsorption was also lower in DCD1 compared with DCD2 (P < 0.05). Adsorption and surface tension were correlated with oxygenation and AWP (P < 0.05). This study has shown that lung function deteriorates with increasing warm ischemic time intervals. BAL protein, surface tension, adsorption, peak AWP and PVR increase significantly after 2 h of warm ischemia together with a significant reduction of the ratio PaO₂/FiO₂.     

Effect of PEEP on regional ventilation during laparoscopic surgery monitored by electrical impedance tomography

Background: Anesthesia per se and pneumoperitoneum during laparoscopic surgery lead to atelectasis and impairment of oxygenation. We hypothesized that a ventilation with positive end‐expiratory pressure (PEEP) during general anesthesia and laparoscopic surgery leads to a more homogeneous ventilation distribution as determined by electrical impedance tomography (EIT). Furthermore, we supposed that PEEP ventilation in lung‐healthy patients would improve the parameters of oxygenation and respiratory compliance. Methods: Thirty‐two patients scheduled to undergo laparoscopic cholecystectomy were randomly assigned to be ventilated with ZEEP (0 cmH₂O) or with PEEP (10 cmH₂O) and a subsequent recruitment maneuver. Differences in regional ventilation were analyzed by the EIT‐based center‐of‐ventilation index (COV), which quantifies the distribution of ventilation and indicates ventilation shifts. Results: Higher amount of ventilation was examined in the dorsal parts of the lungs in the PEEP group. Throughout the application of PEEP, a lower shift of ventilation was found, whereas after the induction of anesthesia, a remarkable ventral shift of ventilation in ZEEP‐ventilated patients (COV: ZEEP, 40.6 ± 2.4%; PEEP, 46.5 ± 3.5%; P<0.001) was observed. Compared with the PEEP group, ZEEP caused a ventral misalignment of ventilation during pneumoperitoneum (COV: ZEEP, 41.6 ± 2.4%; PEEP, 44 ± 2.7%; P=0.013). Throughout the study, there were significant differences in the parameters of oxygenation and respiratory compliance with improved values in PEEP‐ventilated patients. Conclusion: The effect of anesthesia, pneumoperitoneum, and different PEEP levels can be evaluated by EIT‐based COV monitoring. An initial recruitment maneuver and a PEEP of 10 cmH₂O preserved homogeneous regional ventilation during laparoscopic surgery in most, but not all, patients and improved oxygenation and respiratory compliance.     

Gravity is an important determinant of oxygenation during one‐lung ventilation

Background: The role of gravity in the redistribution of pulmonary blood flow during one‐lung ventilation (OLV) has been questioned recently. To address this controversial but clinically important issue, we used an experimental approach that allowed us to differentiate the effects of gravity from the effects of hypoxic pulmonary vasoconstriction (HPV) on arterial oxygenation during OLV in patients scheduled for thoracic surgery. Methods: Forty patients with chronic obstructive pulmonary disease scheduled for right lung tumour resection were randomized to undergo dependent (left) one‐lung ventilation (D‐OLV; n=20) or non‐dependent (right) one‐lung ventilation (ND‐OLV; n=20) in the supine and left lateral positions. Partial pressure of arterial oxygen (PaO₂) was measured as a surrogate for ventilation/perfusion matching. Patients were studied before surgery under closed chest conditions. Results: When compared with bilateral lung ventilation, both D‐OLV and ND‐OLV caused a significant and equal decrease in PaO₂ in the supine position. However, D‐OLV in the lateral position was associated with a higher PaO₂ as compared with the supine position [274.2 (77.6) vs. 181.9 (68.3) mmHg, P<0.01, analysis of variance (ANOVA)]. In contrast, in patients undergoing ND‐OLV, PaO₂ was always lower in the lateral as compared with the supine position [105.3 (63.2) vs. 187 (63.1) mmHg, P<0.01, ANOVA]. Conclusion: The relative position of the ventilated vs. the non‐ventilated lung markedly affects arterial oxygenation during OLV. These data suggest that gravity affects ventilation–perfusion matching independent of HPV.     

Effect of hydrogen sulphide on inflammatory factors of the mitochondria after limb ischaemia‐reperfusion injury in rats

The goal of this study was to evaluate the effect of hydrogen sulphide on inflammatory factors and the energy metabolism of mitochondria after limb reperfusion injury in rats. Sixty Wistar rats were divided into three groups: the sham operated group, the control group (the ischaemia‐reperfusion injury [IRI] + normal saline group), and the experimental group (the IRI + H₂S group). An experimental rat model of limb IRI was established. Skeletal muscle samples were collected to observe the content of necrotic products (including myoglobin (MB), lysophosphatidylcholine (LPC), and lipid peroxidation (LPO)); blood samples were collected to observe changes in the contents of interleukin‐1 (IL‐1), Interleukin‐6 (IL‐6), and tumor necrosis factor‐α (TNF‐α); and the mitochondria of skeletal muscle cells were extracted for mitochondrial transmembrane potential measurement and adenosine triphosphate (ATP) content determination. The results underwent further statistical analysis. The contents of MB, LPC, and LPO in the limb skeletal muscle, liver, lung, and kidney tissues of rats in the control group were significantly increased (P < 0.05) after IRI, which was markedly attenuated by treatment with hydrogen sulphide (P < 0.05). Ischaemia/reperfusion of the lower extremities in rats triggered a significant increase in serum levels of IL‐1, IL‐6, and TNF‐α, which was significantly inhibited by treatment with H₂S during ischaemia/reperfusion. In addition, the inhibitory effect tended to be time‐dependent. After limb ischaemia/reperfusion, the mitochondrial transmembrane potential of skeletal muscle cells in the control group decreased significantly (P < 0.05), while the potential energy of the mitochondrial membrane in the experimental group was significantly higher than that in the control group (P < 0.05). The content of ATP in mitochondria of skeletal muscle cells of ischaemia‐reperfusion rats in the control group was significantly lower than that in the sham operated group (P < 0.05), while the content of ATP of mitochondria in the experimental group after H₂S treatment was significantly higher than the control group (P < 0.05). Hydrogen sulphide can alleviate the injury of skeletal muscle and distal organs after limb ischaemia‐reperfusion and reduce local inflammatory reaction, which is essential in alleviating mitochondrial transmembrane potential and energy metabolism disorder during reperfusion injury. The purpose of the study is to summarise the available information and provide theoretical support for the application of hydrogen sulphide in the treatment of limb IRI in skeletal muscle and distal organs.     

Effect of Ono-EI-600 elastase inhibitor on high-tidal-volume-induced lung injury in rats

We tested the effect of Ono-EI-600, an elastase inhibitor that suppresses cytokine release, on ventilator-induced lung injury in a rat model. After Wistar rats (aged 8–11 weeks) were anesthetized and tracheostomized, they were randomly assigned to four groups: high tidal volume (V_T) group (H group: n = 10) receiving peak inspiratory pressure (PIP) 30 cmH₂O for 240 min; high V_T with drug group (HD group: n = 10) receiving the same ventilation settings as H group and also intravenous infusion 10 mg·kg⁻¹·h⁻¹ of Ono-EI-600 during the protocol; the lower V_T group (L group: n = 5) receiving PIP 10 cmH₂O for 240 min; and control group (C group: n = 5) receiving the same ventilation as L group for 30 min. The cytokine levels (IL-6 and CINC-1) in the bronchoalveolar lavage fluid (BALF) of the H group were significantly higher than those of the C and L groups (P < 0.05). However, for the H and HD groups, no differences were found in arterial blood gas data, cytokine levels in BALF, and histological injury scores. Our experiment provided no evidence that elastase inhibitor Ono-EI-600 protects against lung injury induced by high V_T ventilation.     

Effects of thoracic epidural analgesia on lower urinary tract function in women

Aims: The need for an indwelling transurethral catheter in patients with postoperative thoracic epidural analgesia (TEA) is a matter of controversy. Subjective observations are ambivalent and the literature addressing this issue is scarce. As segmental blockade can be achieved with epidural analgesia, we hypothesized that analgesia within segments T4–T11 has no or minimal influence on lower urinary tract function. Thus, we evaluated the effect of TEA on lower urinary tract function by urodynamic studies. Methods: In 13 women with no preoperative lower urinary tract symptoms undergoing open kidney surgery by lumbotomy under TEA, we prospectively assessed changes in urodynamic parameters the day before and 2–3 days after surgery with the patients under TEA. Results: Before versus during TEA, there was a significant increase in postvoid residual (median, 5 ml vs. 220 ml, P < 0.001) and a significant decrease in maximum detrusor pressure (median, 23 cmH₂O vs. 5 cmH₂O, P = 0.001), detrusor pressure at maximum flow rate (median, 18 cmH₂O vs. 5 cmH₂O, P = 0.001), maximum flow rate (median, 12 ml/sec vs. 3 ml/sec, P < 0.001), and voided volume (median, 250 ml vs. 40 ml, P < 0.001). In addition, maximum urethral closure pressure at rest decreased significantly under TEA from median 75 cmH₂O to 56 cmH₂O (P = 0.002). Bladder sensation, maximum cystometric capacity, compliance, and functional profile length at rest were not influenced by TEA. Conclusions: TEA has a significant effect on bladder emptying with clinically relevant postvoid residual (PVR) necessitating (indwelling or intermittent) catheterization or monitoring of PVR. Neurourol. Urodyn. 30:121–125, 2011. © 2010 Wiley‐Liss, Inc.     

Characteristics of the response of ovine granulocytes (PMNs) to zymosan‐activated serum (ZAS) and to recombinant human interleukin‐8 (IL‐8)

The chemotactic activity of zymosan‐activated serum (ZAS) and of two concentrations of recombinant human IL‐8 (IL‐8₂₅, 25 ng/ml; IL‐8₅₀, 50 ng/ml) for ovine polymorphonuclear granulocytes (PMNs) was tested in a modified Boyden chamber. Thick cellulose acetate filters and the leading front method were used to quantify the movements of the cells. Both ZAS and IL‐8₂₅ exerted a chemotactic effect on ovine PMNs (P < 0.01): IL‐8₅₀ induced a more homogeneous response (P < 0.001). To verify the characteristics of the responsiveness to the chemokines after short‐term (st) or long‐term (lt) repeated samplings, chemotaxis was investigated 1 (T1st), 2 (T2_st), 24 (T3_st) and 48 h (T4_st) after the basal sampling (T0_st) and 15 days (T1_lt) after the basal sampling (T0_lt). No differences in chemotaxis were found in long‐term repeated samplings. In contrast an increase in the responsiveness to IL‐8₂₅ and to IL‐8₅₀ (P < 0.05) was detected at T2_st in comparison with T0_st. Furthermore, the significance of the distance run by activated PMNs compared with the controls, increased from T0_st to T2_st, as a sign of a more homogeneous response to the chemokines. In the absence of evident changes in circulating leucocyte numbers and in serum cortisol concentrations, these findings could be interpreted as a consequence of a different expression of chemoattractant receptors on the membrane of PMNs collected at different times.     

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.     

Effects of different respiratory maneuvers on esophageal sphincters in obese patients before and during anesthesia

Background: Data on esophageal sphincters in obese individuals during anesthesia are sparse. The aim of the present study was to evaluate the effects of different respiratory maneuvers on the pressures in the esophagus and esophageal sphincters before and during anesthesia in obese patients. Methods: Seventeen patients, aged 28–68 years, with a BMI≥35 kg/m², who were undergoing a laparoscopic gastric by‐pass surgery, were studied, and pressures from the hypopharynx to the stomach were recorded using high‐resolution solid‐state manometry. Before anesthesia, recordings were performed during normal spontaneous breathing, Valsalva and forced inspiration. The effects of anesthesia induction with remifentanil and propofol were evaluated, and positive end‐expiratory pressure (PEEP) 10 cmH₂O was applied during anesthesia. Results: During spontaneous breathing, the lower esophageal sphincter (LES) pressure was significantly lower during end‐expiration compared with end‐inspiration (28.5 ± 7.7 vs. 35.4 ± 10.8 mmHg, P<0.01), but barrier pressure (BrP) and intra‐gastric pressure (IGP) were unchanged. LES, BrP (P<0.05) and IGP (P<0.01) decreased significantly during anesthesia. BrP remained positive in all patients. IGP increased during Valsalva (P<0.01) but was unaffected by PEEP. Esophageal pressures were positive during both spontaneous breathing and mechanical ventilation. Esophageal pressures increased during PEEP from 9.4 ± 3.8 to 11.3 ± 3.3 mmHg (P<0.01). Conclusion: During spontaneous breathing, the LES pressure was the lowest during end‐expiration but there were no differences in BrP and IGP. LES, BrP and IGP decreased during anesthesia but BrP remained positive in all patients. During the application of PEEP, esophageal pressures increased and this may have a protective effect against regurgitation.     

The Tulip GT® airway versus the facemask and Guedel airway: a randomised,controlled, cross‐over study by Basic Life Support‐trained airway providers in anaesthetised patients

We performed a randomised, controlled, cross‐over study of lung ventilation by Basic Life Support‐trained providers using either the Tulip GT^® airway or a facemask with a Guedel airway in 60 anaesthetised patients. Successful ventilation was achieved if the provider produced an end‐tidal CO₂ > 3.5 kPa and a tidal volume > 250 ml in two of the first three breaths, within 60 sec and within two attempts. Fifty‐seven (95%) providers achieved successful ventilation using the Tulip GT compared with 35 (58%) using the facemask (p < 0.0001). Comparing the Tulip GT and facemask, the mean (SD) end‐tidal CO₂ was 5.0 (0.7) kPa vs 2.5 (1.5) kPa, tidal volume was 494 (175) ml vs 286 (186) ml and peak inspiratory pressure was 18.3 (3.4) cmH₂O vs 13.6 (7) cmH₂O respectively (all p < 0.0001). Forty‐seven (78%) users favoured the Tulip GT airway. These results are similar to a previous manikin study using the same protocol, suggesting a close correlation between human and manikin studies for this airway device. We conclude that the Tulip GT should be considered as an adjunct to airway management both within and outside hospitals when ventilation is being undertaken by Basic Life Support‐trained airway providers.     

A randomized crossover comparison between the Laryngeal Mask Airway-Unique™ and the air-Q intubating laryngeal airway in children

Objectives: The purpose of this randomized crossover study was to evaluate the feasibility of the air‐Q intubating laryngeal airway (ILA) in clinical practice when compared with the Laryngeal Mask Airway‐Unique^? (LMA‐U), the current standard of care for primary airway maintenance. Aim: We hypothesized that the ILA would have better airway seal pressures and laryngeal alignment than the LMA‐U in anesthetized nonparalyzed children. Background: The ILA is a newer supraglottic airway for children with design features that allow it to be used for primary airway maintenance and as a conduit for tracheal intubations. Methods: Fifty healthy children, 6–36 months of age, 10–15 kg, who were scheduled for elective surgery in which the use of a size two LMA‐U and size 1.5 ILA would be appropriate for airway maintenance, were enrolled into this randomized crossover study. Primary outcome measures were airway leak pressures and fiberoptic grades of view. Secondary outcome measures included ease and time for successful insertion, incidence of gastric insufflation, ventilation parameters, and complications. Results: There were no statistically significant differences in regard to the ease of device insertion, time to ventilation, gastric insufflation, and ventilation parameters between the ILA and the LMA‐U. All devices were successfully placed on the first attempt, and there were no instances of failure. There were statistically significant differences in the airway leak pressure between the ILA (19.0 ± 5.4 cmH₂O) and the LMA‐U (16.1 ± 4.9 cmH₂O), P = 0.001. There were also statistically significant differences in the fiberoptic grades of view between the ILA and LMA‐U, P = 0.004. Conclusions: The ILA had higher airway leak pressures and superior fiberoptic grades of view when compared with the LMA‐U and can be a suitable alternative to the LMA‐U in children weighing 10–15 kg.     

Transsacral rectopexy for recurrent complete rectal prolapse

The aim of this study was to examine the functional outcome of transsacral rectopexy performed with Dexon mesh for recurrent complete rectal prolapse. Anorectal function was assessed by anorectal manometry and defecography, before and from 1 year after surgery in five patients who were followed up for 1–3 years. The fecal incontinence score recovered from a preoperative mean score of 3.8 to a postoperative mean score of 1.2, and constipation was improved in four patients (80%). The straining anorectal angle (S-ARA), measured by defecography, improved from a preoperative value of 120.6°±6.9° to a postoperative value of 98.5°±3.5° (P<0.05), and the perineal descent (PD) improved from a preoperative value of 16.2±2.5 cm to a postoperative value of 8.1±1.3 cm (P<0.05). The maximal resting pressure (MRP) increased from a preoperative value of 20.5±3.7 cmH₂O to a postoperative value of 40.5±4.8 cmH₂O (P<0.05). These findings indicate that transsacral rectopexy with Dexon mesh can achieve good control of recurrent complete rectal prolapse.     

Soluble Human Leukocyte Antigen class I antigen and interleukin‐12 in hepatectomized patients

Background: Interleukin‐12 (IL‐12) has been shown to enhance the cytotoxic activity of NK cells and CTL. IL‐12 also acts as a growth factor for activated NK, T and NKT cells. The soluble HLA class I (sHLA‐I) has been reported to bind a killer‐cell inhibitory receptor, which is expressed on the NK cell, and its signals inhibit NK cell‐mediated cytotoxicity. Effects of fresh frozen plasma (FFP) on post‐operative immune status have not yet been completely examined. Methods: Thirty consecutive patients taking a hepatectomy were enrolled. The levels of IL‐12 and sHLA‐I were examined by enzyme‐linked immunosorbent assay. Results: The rate of complication after hepatectomy in the FFP‐administered patients was higher than that in patients without FFP administration (P= 0.0358). Decreased IL‐12 levels after surgery in patients without FFP administration recovered to the preoperative state earlier than those in patients with FFP administration (P < 0.05). The levels of sHLA‐I in the FFP‐administered patients were higher than those in the patients without FFP administration (P < 0.05). Conclusions: Administration of FFP, which contains sHLA‐I, affected the levels of sHLA‐I after hepatectomy. Both high levels of sHLA‐I and low levels of IL‐12 could attenuate NK activities after hepatectomy, especially when FFP would be administered.     

A randomised,non‐crossover study of the GuardianCPV™ Laryngeal Mask versus the LMA Supreme™ in paralysed,anaesthetised female patients

We investigated the hypothesis that the oropharyngeal leak pressure would differ between the GuardianCPV? and the LMA Supreme? in anaesthetised patients. We randomly assigned 120 patients to receive either the GuardianCPV or the LMA Supreme for airway management. Oropharyngeal leak pressure was measured during cuff inflation from 0 to 40 ml in 10‐ml steps. In addition, intracuff pressure, fibreoptic position of the airway and drain tube, device insertion success, ventilation success, blood staining and airway morbidity were determined. Mean (SD) oropharyngeal leak pressures for clinically acceptable cuff volumes of 20–40 ml were 31 (7) cmH₂O for the GuardianCPV and 27 (7) cmH₂O for the LMA Supreme (p < 0.0001); mean (SD) intracuff pressures were 68 (33) cmH₂O and 88 (43) cmH₂O (p < 0.0001), respectively. We found no differences in device insertion success, ventilation success, fibreoptic position of the airway and drain tube, blood staining or airway morbidity. We conclude that the oropharyngeal leak pressure is better for the GuardianCPV than for the LMA Supreme in anaesthetised patients.     

Capnography reflects ventilation/perfusion distribution in a model of acute lung injury

Background: Changes in the shape of the capnogram may reflect changes in lung physiology. We studied the effect of different ventilation/perfusion ratios (V/Q) induced by positive end‐expiratory pressures (PEEP) and lung recruitment on phase III slope (S_III) of volumetric capnograms. Methods: Seven lung‐lavaged pigs received volume control ventilation at tidal volumes of 6 ml/kg. After a lung recruitment maneuver, open‐lung PEEP (OL‐PEEP) was defined at 2 cmH₂O above the PEEP at the onset of lung collapse as identified by the maximum respiratory compliance during a decremental PEEP trial. Thereafter, six distinct PEEP levels either at OL‐PEEP, 4 cmH₂O above or below this level were applied in a random order, either with or without a prior lung recruitment maneuver. Ventilation–perfusion distribution (using multiple inert gas elimination technique), hemodynamics, blood gases and volumetric capnography data were recorded at the end of each condition (minute 40). Results: S _III showed the lowest value whenever lung recruitment and OL‐PEEP were jointly applied and was associated with the lowest dispersion of ventilation and perfusion (Disp_R?E), the lowest ratio of alveolar dead space to alveolar tidal volume (VD_alv/VT_alv) and the lowest difference between arterial and end‐tidal pCO₂ (Pa?ETCO₂). Spearman's rank correlations between S_III and Disp_R?E showed a ρ=0.85 with 95% CI for ρ (Fisher's Z‐transformation) of 0.74–0.91, P<0.0001. Conclusion: In this experimental model of lung injury, changes in the phase III slope of the capnograms were directly correlated with the degree of ventilation/perfusion dispersion.