Percutaneous tracheostomy and cricothyrotomy techniques

Percutaneous tracheostomy is currently accepted as a standard technique for longer-term airway care in the critically ill patients in many intensive care units (ICUs). Early tracheostomy has not shown any survival benefit compared to late tracheostomy following prolonged tracheal intubation in ICU patients. The main indications for tracheostomy in the ICU setting include weaning from artificial ventilation or airway protection. Nevertheless, many questions about choice of techniques, post-tracheostomy care and decannulation remain unanswered. This review gives an overview of current techniques.     

Randomized evaluation of the size 2 laryngeal tube and classical laryngeal mask airway in different head and neck positions in children under positive pressure ventilation

Purpose

The aim of this study was to evaluate the applicability of the laryngeal tube (LT) size 2 and the classical laryngeal mask airway (LMA) size 2 in different head–neck positions under positive pressure ventilation in children by measuring leak pressures, peak pressures and the achievable tidal volumes under positive pressure ventilation.

Methods

Forty children were randomized to receive airway management by either the LT or LMA as the primary device. Leak pressures, peak pressures and tidal volumes under positive pressure ventilation were measured in the neutral, anteflection, retroversion, left-rotation and right-rotation head–neck positions.

Results

In all head–neck positions, the leak pressures were significantly higher for the LT than for the LMA (neutral 25.9 ± 7.0 vs. 19.1 ± 5.7 cmH₂O; anteflection 29.7 ± 7.1 vs. 24.2 ± 8.9 cmH₂O; retroversion 24.1 ± 7.6 vs. 17.2 ± 6.9 cmH₂O). In both devices, the peak ventilation pressures were higher in the anteflection position (LT 27.1 ± 6.3 cmH₂O; LMA 17.8 ± 6.7 cmH₂O) than in the retroversion position (LT 13.7 ± 3.9 cmH₂O; LMA 12.7 ± 3.6 cmH₂O). Compared to the respirator settings, lower tidal volumes were achieved in the anteflection position (LT 65 ± 48 vs. 129 ± 38 ml, LMA 100 ± 21 vs. 125 ± 29 ml) as compared to the other positions.

Conclusion

Based on our results, we suggest that in anaesthetized children, the size 2 LT, compared to the size 2 LMA, may be more suitable for positive pressure ventilation due to favorable leak and peak pressures. Both devices can be safely used in head–neck positions other than neutral. Most disadvantageous with regards to the measured parameters was the anteflection position, especially for the LT.     

Timing of tracheostomy

Currently, tracheostomy represents an established procedure for airway management in critically ill patients who require long-term respiratory support, and it is one of the most frequently performed surgical procedures in critically ill patients. It offers a number of practical and theoretical advantages when compared to conventional translaryngeal oro- or nasotracheal intubation, but is also associated with a number of serious complications. In the last 20 years, several retrospective studies, randomized prospective trials, and meta-analyses have been published to determine the best timing for tracheostomy. However, these studies presented conflicting results. All studies performed so far in a prospective randomized fashion were relatively small and underpowered. Currently, several large controlled randomized studies are underway that will hopefully help physicians make better evidence-based decisions on the timing of tracheostomy. Based on our current knowledge, the following recommendations might be made on a low level of evidence: on day 2 or 3 after onset of mechanical ventilation (>48 h of mechanical ventilation or need for an artificial airway) tracheostomy should be seriously considered. Before decisions are made, several questions should be answered: Is the situation suitable for tracheostomy? Are there relevant contraindications for the performance of a tracheostomy? What is the most likely course of the underlying respiratory insufficiency? What is the likelihood the patient will stay in need of invasive mechanical ventilation for more than a week, either because of an ongoing impairment of oxygenation, weaning failure, upper airway obstruction, coma or a swallowing disorder? If no relevant contraindication is present and if the need for invasive mechanical ventilation can be expected to last for more than one week, tracheostomy should be planned and performed within the next 2 days.     

A prototype small‐bore ventilation catheter with a cuff: cuff inflation optimizes ventilation with the Ventrain

Background

Ventilation through small‐diameter tubes typically precludes use of a cuff as this will impede the necessary passive outflow of gas alongside the tube's outer surface. Ventrain assists expiration and enables oxygenation and normoventilation through small‐bore cannulas or catheters, particularly in obstructed airways. A small‐bore ventilation catheter (SBVC; 40 cm long, 2.2 mm inner diameter) with a separate pressure monitoring lumen and a cuff was developed. Efficacy of oxygenation and ventilation with Ventrain through this catheter was investigated in sealed and open airways in a porcine cross‐over study.

Methods

Six pigs were ventilated with Ventrain (15 l/min oxygen, frequency 30 breaths per min, I : E‐ratio 1 : 1) through the SBVC, both with the cuff inflated and deflated. Prior to each test they were ventilated conventionally until steady state was achieved.

Results

With an inflated cuff, PaO₂ rose instantly and remained elevated (median [range] PaO₂ 61 [52–69] kPa after 30 min; P = 0.027 compared to baseline). PaCO₂ remained stable at 4.9 [4.2–6.2] kPa. After cuff deflation, PaO₂ was significantly lower (9 [5–28] kPa at 10 min, P = 0.028) and interventional ventilation had to be stopped prematurely in five pigs as PaCO₂ exceeded 10.6 kPa. Pulmonary artery pressures increased markedly in these pigs. Intratracheal pressures were kept between 5 and 20 cmH₂O with the cuff inflated, but never exceeded 2 cmH₂O after cuff deflation.

Conclusion

The SBVC combines the benefits of a small diameter airway and a cuff. Cuff inflation optimizes oxygenation and ventilation with Ventrain.     

Timing of tracheostomy and outcome of patients requiring mechanical ventilation

Objectives

To assess the impact of tracheostomy timing on outcome of critically ill patients requiring mechanical ventilation (MV).

Study design

Retrospective clinical study in a twelve beds intensive care unit (ICU).

Patients and methods

From January 2001 to June 2005, patients under MV who received tracheostomy were divided into 2 groups: early tracheostomy group when tracheostomy was performed before or on day 7 and late tracheostomy group when it was performed thereafter. We compared prevalence of nosocomial pneumonia, length of sedation, lengths of MV, length of stay in ICU, weaning from MV and mortality rates between the 2 groups.

Results

During this period of 4 years and half, 112 patients underwent tracheostomy, 62 of whom had early tracheostomy and 50 had late tracheostomy. Early tracheostomy was associated with significant reduction of length of sedation (10 ± 3 vs 17 ± 5 days, P < 0.001), length of MV (21 ± 19 vs 29 ± 17 days, P = 0.02) and length of stay in ICU (33 ± 22 vs 42 ± 18 days, P = 0.042). There were no differences in prevalence of pneumonia (21% for early tracheostomy group vs 31% for late tracheostomy group, P = 0, 13), weaning from MV (50 vs 36%, P = 0.19), and mortality rates between the 2 groups (38 vs 54%, P = 0.15).

Conclusion

This study demonstrated that early tracheostomy (≤ 7 days), was associated with shorter length of sedation, shorter duration of MV and shorter ICU length of stay, without affecting weaning from MV, prevalence of nosocomial pneumonia or survival.     

Reduced air leakage by adjusting the cuff pressure in pediatric laryngeal mask airways during spontaneous ventilation

Background: Optimal inflation of the laryngeal mask airway (LMA) cuff should allow ventilation with low leakage volumes and minimal airway morbidity. Manufacturer’s recommendations vary, and clinical end‐points have been shown to be associated with cuff hyperinflation and increased leak around the LMA. However, measurement of the intra‐cuff pressure of the LMA is not routine in most pediatric institutions, and the optimal intra‐cuff pressure in the LMA has not been determined in clinical studies. Methods: This was a prospective audit in100 pediatric patients undergoing elective general anesthesia breathing spontaneously via LMA (size 1.5–3). Cuff pressure within the LMA was adjusted using a calibrated pressure gauge to three different values (60, 40, and 20 cmH₂O) within the manufacturers’ recommended LMA cuff pressure range (≤60 cmH₂O). Three corresponding inspiratory and expiratory tidal volumes were recorded, and the differences were calculated as the ‘leak volume’. Results: Compared with 20 and 60 cmH₂O intra‐cuff pressure, measured leakage volumes were the lowest at cuff inflation pressures of 40 cmH₂O [median (range) 0.42 (0.09–1.00) ml·kg^?1] in most patients (83%), while 17% of children demonstrated minimally smaller leakages at 20 cmH₂O [0.51 (0.11–1.79) ml·kg^?1]. Maximum leakage values occurred with cuff pressures of 60 cmH₂O in all groups [0.65 (0.18–1.27) ml·kg^?1] and were not associated with the smallest value of air leakage in any patient. Conclusion: Using cuff manometry, an intra‐cuff pressure of 40 cmH₂O was associated with reduced leak around the LMA while higher (60 cmH₂O) and lower (20 cmH₂O) cuff pressures resulted in higher leak volumes during spontaneous ventilation. In spontaneously breathing children, reducing the intra‐cuff pressure of pediatric‐sized LMAs even below the manufacturers’ recommendations allows ventilation with minimized leakage around the LMA cuff.     

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.     

Gas leak and gastric insufflation during controlled ventilation: face maskversus laryngeal mask airway

Purpose

To compare two airway management techniques, face mask (FM) with oropharyngeal airway and laryngeal mask airway (LMA), with respect to the effectiveness of positive pressure ventilation and airway maintenance.

Methods

After induction of anaesthesia, two airway management techniques (FM or LMA) and three peak pressures (20, 25 and 30 cm H₂O) were randomly applied during controlled ventilation in 60 patients. Data collected included inspiratory and expiratory volumes and presence of gastro-oesophageal insufflation. Leak was calculated by subtracting the expiratory from the inspiratory volume, expressed as a fraction of the inspiratory volume.

Results

Expiratory volumes (mean ± SD) at 20, 25 and 30 cm H₂O for LMA ventilation were 893 ± 260, 986 ± 276 and 1006 ± 262 respectively, and for FM ventilation 964 ± 264, 1100 ± 268 and 1116 ± 261. Leak fractions at 20, 25 and 30 cm H₂O for LMA ventilation were 0.21 ± 0.15, 0.24 ± 0.18 and 0.26 ± 0.18 respectively, and for FM ventilation 0.14 ± 0.09, 0.14 ± 0.09 and 0.12 ± 0.08. The frequency of gastro-oesophageal insufflation was 1.6%, 5% and 5% for the LMA and 5%, 15% and 26.6% for the FM for ventilation pressures of 20, 25 and 30 cm H₂O respectively which was greater with LMA use.

Conclusion

Ventilation was adequate in all patients using both techniques. Leak was pressure dependent and greater with LMA use. Most of the leak was vented to the atmosphere via the pharynx. Gastro-oesophageal insufflation was more frequent with ventilation using the face mask. LMA use with positive pressure ventilation would appear to be a better airway management method than the face mask.     

Effect of timing of tracheostomy on changes in bacterial colonisation of the lower respiratory tract in burned children

Objective

The study aims to evaluate the impact of early and late tracheostomy on microbiological changes in the airways in severely burned children.

Materials and methods

Early tracheostomy is sometimes performed within 3 days after the start of mechanical ventilation regular microbiological surveillance of the respiratory tract was done in all patients. From each sputum, tracheobronchial aspirate and bronchoalveolar lavage (BAL), a microscopic slide was made and the material was seeded in a culture medium. The standard culture media used for the growth of respiratory pathogens are blood agar, McConkey agar, VL agar and chocolate agar. The obtained values were statistically analysed.

Results

In the observed period, a total of 68 children underwent mechanical ventilation in our department. A total of 31 (45.59%) children had undergone surgical tracheostomy (18 patients with early tracheostomy and 13 patients with late tracheostomy). The most common bacterium isolated from the lower respiratory tract in patients with early and late tracheostomy was Acinetobacter baumannii (31.53% resp. 44.30% of all bacterial strains).In patients with early tracheostomy, the ratio of G+/G− during the 6–7th day of mechanical ventilation was 1.29:1 and during the 8–10th day, 1:1.43. In patients with late tracheostomy the G+/G− ratio was 1:2.25 and during the 8–10th day, 1:2.25. There was not any statistically significant deviation in the G+/G− ratio in patients with early and late tracheostomy in any of the monitored periods.

Conclusion

The main reasons for performing early tracheostomy are: extent, localisation and depth of the burn. Difficult weaning in an uncooperative patient, failure of extubation with subsequent reintubation and other complications may be an indication for late tracheostomy.The study confirms that the use of appropriately indicated early tracheostomy provides a microbiological benefit for burned children.     

Work of breathing using different interfaces in spontaneous positive pressure ventilation: helmet,face-mask,and endotracheal tube

Purpose

Noninvasive positive pressure ventilation (NPPV) using a helmet is expected to cause inspiratory trigger delay due to the large collapsible and compliant chamber. We compared the work of breathing (WOB) of NPPV using a helmet or a full face-mask with that of invasive ventilation by tracheal intubation.

Methods

We used a lung model capable of simulating spontaneous breathing (LUNGOO; Air Water Inc., Japan). LUNGOO was set at compliance (C) = 50 mL/cmH₂O and resistance (R) = 5 cmH₂O/L/s for normal lung simulation, C = 20 mL/cmH₂O and R = 5 cmH₂O/L/s for restrictive lung, and C = 50 mL/cmH₂O and R = 20 cmH₂O/L/s for obstructive lung. Muscle pressure was fixed at 25 cmH₂O and respiratory rate at 20 bpm. Pressure support ventilation and continuous positive airway pressure were performed with each interface placed on a dummy head made of reinforced plastic that was connected to LUNGOO. We tested the inspiratory WOB difference between the interfaces with various combinations of ventilator settings (positive end-expiratory pressure 5 cmH₂O; pressure support 0, 5, and 10 cmH₂O).

Results

In the normal lung and restrictive lung models, WOB decreased more with the face-mask than the helmet, especially when accompanied by the level of pressure support. In the obstructive lung model, WOB with the helmet decreased compared with the other two interfaces. In the mixed lung model, there were no significant differences in WOB between the three interfaces.

Conclusion

NPPV using a helmet is more effective than the other interfaces for WOB in obstructive lung disease.

     

Larynxmaske LMA Supreme™

Background

The Laryngeal Mask Airway Supreme (LMA-S) is a new disposable airway device that combines features of the LMA ProSeal? (PLMA, gastric access) and LMA Fastrach? (curved shaft to ease insertion) and has been available since April 2007.

Methods

In a prospective study, 10 final year medical students or first year anesthesia residents, all with limited experience in LMA anesthesia, were requested to manage the airway of anesthetized female patients with the LMA-S size 4, who seemed normal on routine airway examination. Data collection included the success rates and duration for insertion, oropharyngeal leak pressures (OLP), fiber optic position and airway morbidity.

Results

A total of 30 patients were enrolled in the study. Insertion of the LMA-S was possible in 27 (90%) patients at the first attempt and in 3 (10%) at the second attempt. Ventilation was established in 18.3 s (range 10–30 s, standard deviation ±4.2 s). Insertion of a gastric tube was possible in all patients at the first attempt. Mean OLP at the level of 60 cmH₂O cuff pressure was 29.1 cmH₂O (range 21–35 cmH₂O, standard deviation ±4.8 cmH₂O). Laryngeal fit evaluated by fiber optic control was rated as optimal in all patients both immediately after insertion of the LMA-S and after end of surgery. Three patients (10%) complained of mild sore throat. No patient reported dysphagia or dysphonia.

Conclusion

Insertion of the LMA-S was successful and possible in all patients in ≤ 30 s with an optimal laryngeal fit, high OLPs and low airway morbidity. The LMA-S seems to be a device suitable for use in routine anesthesia and which can be safely used by medical personnel with limited clinical experience.     

The effects of tracheostomy cuff deflation during continuous positive airway pressure

Continuous flow positive pressure devices bridge the gap between mechanical and unsupported ventilation in patients recovering from critical illness. At this point, patients are often fully awake, yet the inflated tracheostomy cuff prevents them from speaking or swallowing. The aim of this study was to investigate the effects of cuff deflation. After ethics committee approval and informed consent, we recorded airway pressures with catheters placed 3 cm beyond the distal tracheostomy tip, respiratory rate, heart rate and peripheral oxygen saturation with continuous positive airway pressures set at 5, 7.5 and 10 cmH(2)O with the cuff inflated and deflated. Sixteen patients completed the study. There were small falls in end expiratory pressure on cuff deflation. The median (interquartile range) pressure drop with set airway pressure of 5 cmH(2)O was 0.25 (0-1.4) mmHg, which increased to 1 (0-3) mmHg at 7.5 cmH(2)O and 1.5 (0-4) mmHg at 10 cmH(2)O. These changes were not clinically significant and cardiopulmonary parameters remained stable. All patients were able to vocalise following cuff deflation. Twelve patients passed a blue dye swallow screen within a day of tolerating cuff deflation. These results suggest that pressures fall slightly following cuff deflation but this is associated with respiratory stability and may allow patients to talk and swallow.     

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.     

Application of PEEP using the i-gel during volume-controlled ventilation in anesthetized, paralyzed patients

Purpose

This prospective, randomized trial was designed to assess whether the i-gel supraglottic airway device is suitable for volume-controlled ventilation while applying positive end-expiratory pressure (PEEP) of 5 cmH₂O under general anesthesia. It was believed that this device might improve arterial oxygenation.

Methods

Forty adult patients (aged 20–60 years) scheduled for elective orthopedic surgery were enrolled in this study. Twenty patients were ventilated without external PEEP [zero positive end-expiratory pressure (ZEEP) group], and the other 20 were ventilated with PEEP 5 cmH₂O (PEEP group) after placing an i-gel device. Volume-controlled ventilation at a tidal volume (TV) of 8 ml/kg of ideal body weight, leak volume, and arterial blood gas analysis were investigated.

Results

The incidences of a significant leak were similar in the ZEEP and PEEP groups (3/20 and 1/20, respectively; P = 0.605), as were leak volumes. No significant PaO₂ difference was observed between the two groups at 1 h after satisfactory i-gel insertion (215 ± 38 vs. 222 ± 54; P = 0.502).

Conclusions

The use of an i-gel during PEEP application at 5 cmH₂O did not increase the incidence of a significant air leak, and a PEEP of 5 cmH₂O failed to improve arterial oxygenation during controlled ventilation in healthy adult patients.     

The LTD laryngeal tube: a new single-use airway device

Objectives

Clinical study of a new supraglottic single use airway device, the LTD™ with evaluation of insertion, efficiency during intermittent positive pressure ventilation and side effects.

Study design

Prospective, open clinical study.

Patients and methods

Fifty adult patients [33 years (26–55)] were scheduled for elective surgery (orthopaedic, plastic or maxillo-facial) under general anaesthesia less than two hours in dorsal position. No patient presented clinical sign of difficult airway management or risk of regurgitation. We studied easiness and delay for insertion, oro-pharyngeal leak pressure, peak airway pressure with positive pressure ventilation and side effects during the first 24 hours.

Results

Insertion was successful in 94%. Median insertion time was 38 s (32–45). Difficulties of insertions were found in 25%. Oro-pharyngeal leak pressure, always superior than peak pressure [18 cmH₂O (15–21)] increased from 26 cmH₂O (22–32.5) to 34 cmH₂O (29–40) at the end of the surgery. No case of gastric inflation, regurgitation or SpO₂ < 95% were noticed. Moderate sore throat incidence was 6% in recovery room, 15% at the sixth hour and absent at the 24th hour.

Conclusion

The learning curve was low ≤ 10. Insertion is easy. The quality of airway protection allows secure positive pressure ventilation. Postoperative side effects are minor and transient.     

A randomised comparison of the LMA SupremeTM and LMAProSealTM in children

We conducted a randomised trial comparing the size‐2 LMA Supreme? with the LMA ProSeal? in 60 children undergoing surgery. The outcomes measured were airway leak pressure, ease and time for insertion, fibreoptic examination, incidence of gastric insufflation, ease of gastric tube placement, quality of the airway during anaesthetic maintenance and complications. There were no statistically significant differences between the LMA Supreme and LMA ProSeal in median (IQR [range]) insertion time (12 (10–15 [7–18]) s vs 12 (10–13 [8–25]) s; p = 0.90), airway leak pressures (19 (16–21 [12–30]) cmH₂O vs 18 (16–24 [10–34]) cmH₂O; p = 0.55), fibreoptic position of the airway or drain tube, ease of gastric access and complications. Both devices provided effective ventilation requiring minimal airway manipulation. The LMA Supreme can be a useful alternative to the LMA ProSeal when single‐use supraglottic devices with gastric access capabilities are required.     

A randomised comparison of the Ambu® AuraGain™ and the LMA® supreme in infants and children

We conducted a randomised trial in 100 children in order to compare the clinical performance of the Ambu^® AuraGain^? and the LMA^® Supreme^* for airway maintenance during mechanical ventilation. The primary outcomes were initial and 10‐min airway leak pressures. Ease, time and success rates for device and gastric tube insertion, fibreoptic grades of view, airway quality during anaesthetic maintenance, and complications were also assessed. There were no differences in the initial and ten min airway leak pressures between the Ambu AuraGain and LMA Supreme, median (IQR [range]) initial: 19 (16–22 [10–34]) vs 18 (14–24 [8–40]) cmH₂O, p = 0.4; and ten min: 22 (18–26 [11–40]) vs 20 (16–26 [12–40]) cmH₂O, p = 0.08, respectively. Ease, time and success rates for device placement, gastric tube insertion and complications were also not significantly different. Children receiving the LMA Supreme required more airway manouevers (7 vs 1 patient, p = 0.06) to maintain a patent airway. Our results suggest that the Ambu AuraGain may be a useful alternative to the LMA Supreme, as demonstrated by comparable overall clinical performance in children.     

The association of postoperative pulmonary complications in 109,360 patients with pressure‐controlled or volume‐controlled ventilation

We thought that the rate of postoperative pulmonary complications might be higher after pressure‐controlled ventilation than after volume‐controlled ventilation. We analysed peri‐operative data recorded for 109,360 adults, whose lungs were mechanically ventilated during surgery at three hospitals in Massachusetts, USA. We used multivariable regression and propensity score matching. Postoperative pulmonary complications were more common after pressure‐controlled ventilation, odds ratio (95%CI) 1.29 (1.21–1.37), p < 0.001. Tidal volumes and driving pressures were more varied with pressure‐controlled ventilation compared with volume‐controlled ventilation: mean (SD) variance from the median 1.61 (1.36) ml.kg^?1 vs. 1.23 (1.11) ml.kg^?1, p < 0.001; and 3.91 (3.47) cmH₂O vs. 3.40 (2.69) cmH₂O, p < 0.001. The odds ratio (95%CI) of pulmonary complications after pressure‐controlled ventilation compared with volume‐controlled ventilation at positive end‐expiratory pressures < 5 cmH₂O was 1.40 (1.26–1.55) and 1.20 (1.11–1.31) when ≥ 5 cmH₂O, both p < 0.001, a relative risk ratio of 1.17 (1.03–1.33), p = 0.023. The odds ratio (95%CI) of pulmonary complications after pressure‐controlled ventilation compared with volume‐controlled ventilation at driving pressures of < 19 cmH₂O was 1.37 (1.27–1.48), p < 0.001, and 1.16 (1.04–1.30) when ≥ 19 cmH₂O, p = 0.011, a relative risk ratio of 1.18 (1.07–1.30), p = 0.016. Our data support volume‐controlled ventilation during surgery, particularly for patients more likely to suffer postoperative pulmonary complications.     

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.     

Laryngeal mask airways – to inflate or to deflate after insertion?

Background: Hyperinflation of the laryngeal mask airway (LMA) cuff is known to be a risk factor for airway morbidity and increased leakage around the LMA. While the manufacturers’ recommendation is to inflate the cuff with the maximum recommended volumes and/or to adjust the cuff pressure to <60 cmH₂O, cuff pressures below 40 cmH₂O have been shown to be associated with a minimal rate of sore throat and minimal leakage. However, it remains to be determined whether inflation or deflation is needed to achieve favorable pressures. Therefore, we assessed the need for cuff‐volume adjustment following insertion of the LMA unchanged straight from the sterile packaging in a prospective audit. Methods: One thousand children (0–16 years) undergoing elective surgery were consecutively included in this quality of care audit. After taking the LMA from its sterile packaging, the LMA cuff was emptied and the amount of air recorded. Then, the same amount of air was returned into the LMA, the LMA was inserted into the patient, and the cuff pressure was measured using a calibrated cuff manometer. Results: Following insertion of the LMA (without further inflation or deflation of the cuff), 20.5% of children had cuff pressures ≥60 cmH₂, while 55.7% had LMA cuff pressures <40 cmH₂O. Cuff pressures were also significantly higher in size 1 LMAs (66.6% had cuff pressures ≥60 cmH₂O and 2% <40 cmH₂O) compared with all other sizes (P < 0.05). Furthermore, cuff pressures in LMAs with a poly vinyl chloride (PVC) surface were higher compared to LMAs with a silicone surface (65.2%≥60 cmH₂O and 9.3% <40 cmH₂O vs 9%≥60 cmH₂O and 67.6% <40 cmH₂O, respectively). Conclusions: This study demonstrates that LMAs, particularly when using small‐sized LMAs or LMAs with a more rigid PVC surface, need to be deflated following insertion of the device rather than inflated to avoid cuff hyperinflation. Hence, cuff pressures should be measured routinely using a manometer to minimize potential pressure‐related airway complications.