Intracuff pressure during one-lung ventilation in infants and children

A novel approach to calculate the required volume of air for bronchial blockers in young children

INTRODUCTION

Bronchial blocker balloons inflated with small volumes of air increase balloon pressure, involving a risk of airway injury especially in young children. However, there are no established guidelines regarding the appropriate volumes of air required to provide safe bronchial occlusion.

METHODS

This study aimed to introduce a novel method for calculating the amount of air required for safe bronchial blocker balloon occlusion for one lung anesthesia in young children. We included 79 pediatric patients who underwent video-assisted thoracoscopic surgery at our hospital. Preoperatively, the balloon pressure and corresponding diameter of 5F bronchial blockers inflated with different volumes of air were measured. Intraoperatively, bronchial diameters measured by computerized tomographic scans were matched to the ex vivo measured balloon diameters. The quality of lung isolation, incidence of balloon repositioning, and airway injury were documented. Postoperatively, airway injury was evaluated through fiberoptic bronchoscopy.

RESULTS

Balloon pressure and balloon diameter showed linear and nonlinear correlations with volume, respectively. The median lengths of the right and left mainstem bronchi were median (interquartile range) range: 5.3 mm (4.5-6.3) 2.7-8.15 and 21.8 (19.6-23.4) 14-29, respectively. Occluding the left mainstem bronchus required <1 mL of air, with a balloon pressure of 27 cm H2O. The isolation quality was high with no case of mucosal injury or displacement. Occluding the right mainstem bronchus required a median air volume of 1.3 mL, with a median balloon pressure of 44 cm H2O. One patient had poor lung isolation due to a tracheal bronchus and another developed mild and transient airway injury.

CONCLUSION

The bronchial blocker cuff should be regarded as a high-pressure balloon. We introduced a new concept for safe bronchial blocker balloon occlusion for one-lung ventilation in small children.

Practical Review of Mechanical Ventilation in Adults and Children in The Operating Room and Emergency Department

BACKGROUND

During general anesthesia, mechanical ventilation can cause pulmonary damage through mechanism of ventilator-induced lung injury which is a major cause of postoperative pulmonary complications, which varies between 5 and 33% and increases significantly the 30-day mortality of the surgical patient.

OBJECTIVE

The aim of this review is to analyze different variables which played key role in safe application of mechanical ventilation in the operating room and emergency setting.

METHOD

Also, we wanted to analyze different types of population that underwent intraoperative mechanical ventilation like obese patients, pediatric and adult population and different strategies such as one lung ventilation and ventilation in trendelemburg position. The peer-reviewed articles analyzed were selected according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) from Pubmed/Medline, Ovid/Wiley and Cochrane Library, combining key terms such as: "pulmonary post-operative complications", "protective ventilation", "alveolar recruitment maneuvers", "respiratory compliance", "intraoperative paediatric ventilation", "best peep", "types of ventilation". Among the 230 papers identified, 150 articles were selected, after title - abstract examination and removing the duplicates, resulting in 94 articles related to mechanical ventilation in operating room and emergency setting that were analyzed.

RESULTS

Careful preoperative patient's evaluation and protective ventilation (i.e. use of low tidal volumes, adequate PEEP and alveolar recruitment maneuvers) has been shown to be effective not only in limiting alveolar de-recruitment, alveolar overdistension and lung damage, but also in reducing the onset of pulmonary post-operative complications (PPCs).

CONCLUSION

Mechanical ventilation is like "Janus Bi-front" because it is essential for surgical procedures, for the care of critical care patients and in life-threatening conditions but it can be harmful to the patient if continued for a long time and where an excessive dose of oxygen is administered into the lungs. Low tidal volume is associated with minor rate of PPCs and other complications and every complication can increase length of Stay, adding cost to NHS between 1580 € and 1650 € per day in Europe and currently the prevention of PPCS is only weapon that we possess.

A Comparison of the Required Bronchial Cuff Volume Obtained by 2 Cuff Inflation Methods, Capnogram Waveform-Guided Versus Pressure-Guided: A Prospective Randomized Controlled Study

BACKGROUND

Double-lumen endobronchial tubes (DLTs) are used for one-lung ventilation (OLV) during thoracic surgery. Overinflation into the bronchial cuff causes damage to the tracheobronchial mucosa, whereas underinflation leads to an incomplete collapse of the nonventilated lung or incomplete ventilation of the ventilated lung. However, how to determine the appropriate bronchial cuff volume and pressure during OLV is unclear. The objective of this study is to compare the required bronchial cuff volume for lung separation obtained by 2 different cuff inflation methods under closed- and open-chest conditions.

METHODS

A total of 64 patients scheduled to undergo elective thoracic surgery requiring OLV were recruited. Left DLTs were used for both right- and left-sided surgery. The patients were randomly assigned to 1 of 2 inflation-type groups to estimate the bronchial cuff volume. In the capnogram waveform-guided bronchial cuff inflation group (capno group, n = 27), the bronchial cuff was inflated until a capnometer sampling gas containing CO2 from the nonventilated lung displayed a flat line. The corresponding bronchial cuff volume and pressure were then recorded. In the pressure-guided bronchial cuff inflation group (pressure group, n = 29), the bronchial cuff was inflated by a cuff inflator to a pressure of 20 cm H2O. Lung separation was confirmed when a flat line of a capnometer was observed after gas sampling from the nonventilated lung.

RESULTS

Under closed-chest conditions, the bronchial cuff sealing volume for the capno group was significantly lower than that for the pressure group (mean [standard deviation {SD}], 1.00 [0.65] mL vs 1.44 [0.59] mL, mean difference, -0.44; 97.5% confidence interval [CI], -0.78 to -0.11; P = .010). Under open-chest conditions, the bronchial cuff sealing volume for the capno group was also significantly lower than that for the pressure group (mean [SD], 0.65 [0.66] mL vs 1.22 [0.45] mL, mean difference, -0.58; 97.5% CI, -0.88 to -0.27; P < .001).

CONCLUSIONS

The lowest cuff volume providing an air-tight bronchial seal was obtained by the capnogram waveform-guided bronchial cuff inflation method. Since the cuff volume required to achieve an air-tight seal decreases after opening the chest, readjustment of the bronchial cuff volume to prevent bronchial cuff damage to the tracheobronchial mucosa after opening the chest may be advisable.

Effects of bronchial blockers on gas exchange in infants with one-lung ventilation: a single-institutional experience of 22 cases

BACKGROUND

One-lung ventilation (OLV) in infants is a commonly used airway technique during thoracic surgery. Current research has primarily focused on the operation of the airways and the occurrence of complications. However, there has been minimal data on the pulmonary gas exchange in infants before and after OLV. This study aimed to assess the efficacy of bronchial blockers (BBs) on the pulmonary gas exchange in infants with OLV.

METHODS

A total of 22 infants requiring OLV from January 2017 to August 2019 were included in this study. OLV was achieved by placing BBs outside the endotracheal tube, and all surgeries were performed by the same experienced anesthesiologist. Numerous clinical features, including the oxygenation index (OI), alveolar-arterial oxygen tension gradient (P_A-aO₂), pulmonary dynamic compliance (Cdyn), OLV time, pulmonary collapse time, degree of pulmonary collapse at the operative side, operative time, and immediate hemodynamic indexes before and after intubation were assessed. Data from the arterial blood gases and the ventilator's parameters were obtained at three time points: 15 minutes before OLV (pre-OLV), 15 minutes after the initiation of OLV (during OLV), and 15 minutes after the termination of OLV (post-OLV).

RESULTS

For all patients, the pulmonary gas exchange during OLV was significantly different from both pre-OLV and post-OLV. However, no significant changes of pulmonary function were observed before and after OLV. Extended OLV time was associated with decreased OI and Cdyn, and increased P_A-aO₂ gradient (P<0.001). In addition, no significant changes of hemodynamic indexes before and after intubation were detected. The degree of lung collapse on the operational side during OLV was optimal.

CONCLUSIONS

In this study, the efficacy of BBs on the pulmonary gas exchange in infants with OLV was assessed. The results suggested that although each parameter of pulmonary function pre-OLV were similar to those of post-OLV, an extended period of OLV may lead to compromised lung function.

The Comparison Between Bronchial Occlusion and Artificial Pneumothorax for Thoracoscopic Lobectomy in Infants

OBJECTIVE

To compare the difference between single-lung ventilation with bronchial occlusion and double-lung ventilation with carbon dioxide artificial pneumothorax for thoracoscopic lobectomy in infants.

DESIGN

This was a retrospective study.

SETTING

It was done in a teaching hospital.

PARTICIPANTS

Between March 2017 and April 2020, a total of 72 infants underwent thoracoscopic lobectomy in the authors' hospital.

INTERVENTIONS

Twenty-one patients received single-lung ventilation with bronchial occlusion, and 51 patients received carbon dioxide (CO₂) artificial pneumothorax.

MEASUREMENTS

The patient data included the endotracheal tube length, surgical exposure, intraoperative blood loss, and surgery duration. The mean arterial pressure (MAP), central venous pressure (CVP) and peak inspiratory pressure (Ppeak), partial pressure of oxygen in arterial blood (PaO₂), and partial pressure of carbon dioxide in arterial blood (PaCO₂) were measured at four points: time of bilateral lung ventilation before the thoracic surgery (T0), 10 minutes after the surgery started (T1), 30 minutes after the surgery started (T2), 60 minutes after the surgery started (T3), and 10 minutes after the surgery was over (T4).

MAIN RESULTS

Compared to artificial pneumothorax, the bronchial occlusion group has the following advantages: the surgical exposure was better, the surgery duration was shorter, there was less intraoperative bleeding, and the duration of tracheal intubation was shorter (p < 0.05); bronchial occlusion resulted in a lower MAP but a higher CVP in infants at T1, T2, and T3 (p < 0.05) than the artificial pneumothorax group and resulted in a lower PaCO₂ and higher PaO₂ at T2, T3, and T4 (p < 0.05). There was no significant difference in Ppeak between the two groups (p > 0.05).

CONCLUSION

Compared with CO₂ artificial pneumothorax, bronchial occlusion is more favorable for thoracoscopic lobectomy in infants.