Fluoroscopic-assisted endobronchial intubation for single-lung ventilation in infants

Objective: Review our institutional experience with an alternative to fiberoptic‐guided endobronchial intubation. Aim: The aim of this retrospective cohort study was to present our experience with the use of fluoroscopy to facilitate endobronchial lung isolation in infants undergoing thoracoscopic procedures. Background: Anesthesiologists are more frequently being asked to anesthetize infants and small children for thoracoscopic surgery. Typically, endobronchial intubation or bronchial blockers are utilized to achieve lung isolation during these procedures. However, sometimes small and complicated anatomy can make this challenging. Methods: Respective chart review over a 13‐month period of infants undergoing thoracoscopic excision of congenital lung lesions at the Children’s Hospital of Philadelphia. Rate of success in achieving lung isolation along with time of fluoroscopy exposure were recorded. Results: Twenty infants had thoracoscopic lung surgery attempted during the period of the review. Lung isolation was successfully achieved in all of the patients. The average exposure to fluoroscopy was 83.7 s (range 20–320 s). Conclusions: Fluoroscopic aided lung isolation is a reliable and effective alternative method to the use of fiberoptic bronchoscope for endobronchial intubation in infants.     

Respiratory and haemodynamic effects of conventional volume controlled PEEP ventilation, pressure regulated volume controlled ventilation and low frequency positive pressure ventilation with extracorporeal carbon dioxide removal in pigs with acute ARDS

The purpose of this study was to evaluate whether any benefit of low frequency positive pressure ventilation with extracorporeal carbon dioxide removal (LFPPV–ECCO₂R) existed over either volume controlled ventilation (VCV) with measured best–PEEP or pressure regulated volume controlled ventilation (PRVCV) with an inspiration/expiration (I/E) ratio of 4:1, with respect to arterial oxygenation, lung mechanics and haemodynamics, in acute respiratory failure.
Fifteen adult pigs were used for the study. Respiratory failure was induced by surfactant depletion by repeated lung lavage. The different therapeutic approaches were applied randomly to each pig for 1 h. Measurements of gas exchange, airway pressures and haemodynamics were performed during ventilatory and haemodynamic steady state. Paco₂ was kept constant in all modes.
At almost similar total–PEEP, Pao₂ values were significantly higher with LFPPV–ECCO₂R comared to VCV with best–PEEP. Peak inspiratory pressure (PIP) and intrapulmonary pressure amplitude defined as the difference between PIP and total–PEEP were significantly lower with PRVCV and LFPPV–ECCO₂R compared to VCV with best–PEEP. There was no significant difference between the modes concerning cardiocircu–latory parameters.
PRVCV with I/E ratio of 4:1 and LFPPV–ECCO₂R proved to be better modes to achieve better gas exchange and lower PIP at lower intrapulmonary pressure amplitudes. It is concluded that PRVCV is an adequate form of treatment under these experimental conditions imitating acute respiratory failure, without necessitating other invasive measures.     

Whole-lung lavage in infants and children with pulmonary alveolar proteinosis

Background: Pulmonary alveolar proteinosis (PAP) is a rare alveolar filling syndrome where the mainstay of treatment is therapeutic whole‐lung lavage (WLL). WLL techniques used in adults have to be modified for children because of their small‐diameter airways. Aim: To describe a technique for WLL adapted for small children. Methods: We describe a WLL technique that combines safe single‐lung ventilation with the use of an age‐appropriate endotracheal tube and selective occlusion of the other main bronchus with a balloon catheter through which the lavage is performed. Effectiveness measured by change in oxygen requirements and adverse effects was noted. Results: We performed 64 WLL procedures in four children (age 13 months to 7 years; body weight 4.7–14 kg). Two children had idiopathic and two had secondary PAP. At referral, all children had dyspnoea at rest and required continuous oxygen supplementation. Two patients showed significantly decreased oxygen demands and radiological improvement after WLL. Two patients showed no significant response. The only adverse effect observed was transient hypoxemia. Complications comprised fluid leak at the balloon (4), balloon rupture (1), and pneumothorax (1). Conclusions: This technique for WLL combining single‐lung ventilation with an endotracheal tube and lung exclusion for lavage with a balloon catheter can be safely and effectively performed in small children with PAP.     

Single-lung ventilation in infants and children

During the past decade, the use of video-assisted thoracoscopic surgery (VATS) has dramatically increased in children as well as adults. Although VATS can be performed while both lungs are being ventilated, single-lung ventilation (SLV) is desirable during VATS. In addition, anaesthesiologists are performing (and paediatric surgeons are requesting) SLV more frequently for open thoracotomies in infants and children.     

Protective ventilation to reduce inflammatory injury from one lung ventilation in a piglet model

Objectives: To test the hypothesis that protective ventilation strategy (PVS) as defined by the use of low stretch ventilation (tidal volume of 5 ml·kg^?1 and employing 5 cm of positive end expiratory pressure (PEEP) during one lung ventilation (OLV) in piglets would result in reduced injury compared to a control group of piglets who received the conventional ventilation (tidal volume of 10 ml·kg^?1 and no PEEP). Background: PVS has been found to be beneficial in adults to minimize injury from OLV. We designed the current study to test the beneficial effects of PVS in a piglet model of OLV. Methods: Ten piglets each were assigned to either ‘Control’ group (tidal volume of 10 ml·kg^?1 and no PEEP) or ‘PVS’ group (tidal volume of 5 ml·kg^?1 during the OLV phase and PEEP of 5 cm of H₂O throughout the study). Experiment consisted of 30 min of baseline ventilation, 3 h of OLV, and again 30 min of bilateral ventilation. Respiratory parameters and proinflammatory markers were measured as outcome. Results: There was no difference in PaO₂ between groups. PaCO₂ (P < 0.01) and ventilatory rate (P < 0.01) were higher at 1.5 h OLV and at the end point in the PVS group. Peak inflating pressure (PIP) and pulmonary resistance were higher (P < 0.05) in the control group at 1.5 h OLV. tumor necrosis factor‐alpha (P < 0.04) and IL‐8 were less (P < 0.001) in the plasma from the PVS group, while IL‐6 and IL‐8 were less (P < 0.04) in the lung tissue from ventilated lungs in the PVS group. Conclusions: Based on this model, PVS decreases inflammatory injury both systemically and in the lung tissue with no adverse effect on oxygenation, ventilation, or lung function.     

Haemodynamic changes during thoracoscopic surgery the effects of one-lung ventilation compared with carbon dioxide insufflation

We investigated the haemodynamic and respiratory effects of one-lung ventilation and carbon dioxide insufflation in 13 adult patients undergoing video-assisted thoracoscopy. Cardiorespiratory variables were determined during carbon dioxide insufflation at intrahemithoracic pressures of 5, 10 and 15 mmHg, and after 5 and 15 min of one-lung ventilation. Carbon dioxide insufflation was associated with a clear deterioration in circulatory function. The cardiac index decreased subsequent to increasing intrathoracic pressures. The mean cardiac index (SD) at pressures of 10 and 15 mmHg was 1.86 (0.39) and 1.52 (0.46), respectively, and may be compared with the reduced venous return consistent with tension pneumothorax. One-lung ventilation did not affect haemodynamic variables but reduced arterial oxygenation indices (PaO2/FIO2) from 424.29 (160.79) after induction of anaesthesia, to 207.72 (125.50) after 5 min and 172.04 (72.03) after 15 min of one-lung ventilation, respectively. The oxygenation index was not influenced by intrahemithoracic carbon dioxide insufflation. One-lung ventilation via a double-lumen endobronchial tube is safe and convenient for video-assisted thoracoscopic surgery. It has no further consequences on haemodynamic variables, whereas the compression of the lung by carbon dioxide insufflation may cause circulatory dysfunction.     

Hemodynamic effects of high frequency ventilation superimposed on intermittent positive pressure ventilation in dogs

The hemodynamic effects of high frequency ventilation (HFV) superimposed on intermittent positive pressure ventilation (IPPV) in seven dogs before and after thrombin infusion were investigated. HFV was superimposed on a Servo 900 B ventilator by a Siemens Elema HFV prototype unit. Mean arterial blood pressure, heart rate, central venous pressure, pulmonary artery pressure, cardiac output, right and left ventricular pressures, pleural pressure, arterial blood gases, and right and left ventricular ejection fractions were recorded. Measurements were done during IPPV alone and during HFV superimposed on IPPV. The HFV frequencies were 5, 15, and 20 Hz at a constant minute volume of 5 1. When HFV was started, the IPPV minute volume was reduced to one third of the initial volume. No significant changes in the measured parameters were observed during the different ventilatory modes either before or after thrombin infusion which doubled the pulmonary vascular resistance. It is concluded that high frequency ventilation superimposed on IPPV might be a ventilatory mode that offers cardiovascular stability and reduces the risk of barotrauma.     

The hemodynamic effect of total liquid ventilation in piglets with reduced cardiac function after cardiopulmonary bypass

Total liquid ventilation (TLV) is a promising treatment for severe lung injury and heart resuscitation. We aim to investigate the hemodynamic effect of TLV in piglets with preexisting cardiac dysfunction. After onset of cardiopulmonary dysfunction induced by cardiopulmonary bypass (CPB), piglets were randomly treated with TLV (n = 6) or conventional gas ventilation (n = 6) for 240 min. Hemodynamics was monitored before and at a 30-min interval after CPB. CPB with cardiac arrest resulted in significant decrease in cardiac index (CI) (96.19 ± 6.74 vs. 48.58 ± 3.96 mL/min/kg, P < 0.001) and increase of pulmonary vascular resistance (PVR) (1123.38 ± 198.97 vs. 8180.62 ± 1041.35 dyne·s/cm(5), P < 0.001). Compared with conventional gas ventilation, there was no further significant decrease of CI or increase of PVR during TLV throughout the experiment. No significant difference was observed on other hemodynamic variables including heart rate, mean arterial pressure, mean pulmonary arterial pressure, and central venous pressure between both groups. The fluctuation of mean arterial blood pressure was 3.95 ± 1.68 mm Hg during TLV. No evidence of fluorothorax or cardiac tamponade was observed in either group. We conclude that TLV does not further impair hemodynamics in piglets with preexisting cardiac dysfunction immediately after CPB.     

The effects of experimental venous carbon dioxide embolization on hemodynamic and respiratory variables

BACKGROUND: Laparoscopic liver resection is a relatively new surgical procedure. Carbon dioxide (CO2) pneumoperitoneum and laparoscopic liver dissection are recognized as risk factors for CO2 embolism to the pulmonary circulation. The embolization can be difficult to detect and can theoretically increase peri-operative morbidity. The aim of this study was to evaluate the cardiopulmonary effects in a pig model during a time period of 4 h after an experimental CO2 embolization. METHODS: Eleven piglets were anesthesized. Nine were embolized with a single intravenous injection of 0.4 ml/kg CO2 and two served as controls. Respiratory and cardiovascular variables, including pulmonary artery pressure and cardiac output, were monitored for 4 h after embolization, and arterial blood gases were monitored on-line. RESULTS: The embolized piglets had an increase in ventilatory dead space, pulmonary vascular resistance and pulmonary artery pressure and a decrease in cardiac output that lasted throughout the 4-h observation time. The mean arterial pressure and heart rate were unchanged. An early sign of embolization was a rapid fall in end-tidal CO2 and P(a)O2 and a rise in P(a)CO2. CONCLUSION: Negative changes in cardiopulmonary physiology persisted for at least 4 h after a single intravenous CO2 injection, in spite of this gas being highly soluble in blood. This is a more prolonged influence of CO2 embolization than previously described. Extensive monitoring for early detection of an embolization may be recommended to limit morbidity in patients undergoing laparoscopic liver surgery.     

Reduced CO2-elimination during combined high-frequency ventilation compared to conventional pressure-controlled ventilation in surfactant-deficient piglets

Background: Combined high-frequency ventilation (CHFV) combines a conventional low-frequency component with superimposed high-frequency jet pulses. The intention is to overcome the limited CO₂-elimination of high-frequency ventilation, and to decrease airway pressures and enhance hemodynamic performance by reducing the conventional component. The present study was performed to compare the effects of conventional continuous positive-pressure ventilation (CPPV) on gas exchange, airway pressures and cardiac output to those of CHFV at matched minute volume (MV) and mean airway pressure (MPAW). Methods: Sixteen anaesthetised piglets with lavage-induced surfactant deficiency were ventilated with CPPV, with positive end-expiratory pressure (PEEP) set to obliterate the lower inflection point of the inspiratory pressure-volume loop. This setting was compared to CHFV during which 50% of the total MV was applied as superimposed jet pulses of 20 Hz at otherwise unchanged settings, and to CPPV at a PEEP level which was reduced (CPPV_red) until MPAW matched MPAW during CHFV. Gas exchange, airway pressures and hemodynamics were measured after the ventilatory setting had been applied for 20 min. Results: MPAW decreased from (median) 2.7 kPa with CPPV to 2.4 kPa with CHFV (P≤0.05). Peak inspiratory pressure was 3.6 kPa with CPPV, 3.2 kPa with CHFV, and 3.2 kPa with CPPV_red (P≤0.05 for differences to CPPV), respectively. PaCO₂ was comparable during CPPV (5.9 kPa), CPPV_red and CHFV_CO2, while it increased during CHFV (6.8 kPa, (P≤0.05)). Cardiac output did not differ significantly between the settings. Conclusions: In the porcine lavage model, CO₂-elimination is reduced during CHFV compared to CPPV at matched minute volume. At matched mean airway pressure, CHFV fails to reduce peak inspiratory airway pressure and to improve hemodynamic performance compared to CPPV.     

Experimental model of laryngotracheal stenosis in infants: effects of different high-frequency jet ventilation patterns on pulmonary parameters

Background: Supraglottic high‐frequency jet ventilation (HFJV) in laryngotracheal surgery in infants with modified jet laryngoscopes offers the surgeon an unimpaired operating field. However, supraglottic HFJV is associated with the development of high airway pressures, inadvertent positive end‐expiratory pressure (PEEP) levels, and barotrauma. Methods: We investigated the total lung volumes (TLV) and tidal volume variations at peak inspiratory pressure levels (PIP) and at PEEP levels along with the pulmonary pressures (PIP and PEEP) during two conventional methods of supraglottic HFJV in an infant trachea–lung model without stenosis and with different degrees of stenosis. Results: With augmentation of the driving pressure in the experiment without stenosis, the TLV plus the pulmonary pressures increased. With narrowing of the stenosis, TLV reduced at PIP level and increased at PEEP level. Volume shifts were significantly higher during superimposed HFJV compared with monofrequent HFJV at equivalent stenosis diameter (P < 0.05) except for the setting with 0.3 bar driving pressure (P > 0.05). The pulmonary PIP was in none of the test series higher than 20 mbar, and the pulmonary PEEP did not exceed 14 mbar. Conclusions: The results from our experimental model support the safe and effective clinical use of supraglottic HFJV in infants with tracheal stenosis. Moderate driving pressures provide acceptable pulmonary pressures in normal compliant lungs.     

Early treatment with arteriovenous extracorporeal lung assist and high-frequency oscillatory ventilation in a case of severe acute respiratory distress syndrome

BACKGROUND: Lung protective ventilation can reduce mortality in acute respiratory distress syndrome (ARDS). However, many patients with severe ARDS remain hypoxemic and more aggressive ventilation is necessary to maintain sufficient gas exchange. Pumpless arteriovenous extracorporeal lung assist (av-ECLA) has been shown to remove up to 95% of the systemic CO(2) production, thereby allowing ventilator settings and modes prioritizing oxygenation and lung protection. High-frequency oscillatory ventilation (HFOV) is an alternative form of ventilation that may improve oxygenation while limiting the risk of further lung injury by using extremely small tidal volumes (VT). METHODS: We discuss the management of a patient suffering from severe ARDS as a result of severe bilateral lung contusions and pulmonary aspiration. RESULTS: Severe ARDS developed within 4 h after intensive care unit admission. Conventional mechanical ventilation (CV) with high-airway pressures and low VT failed to improve gas exchange. Av-ECLA was initiated to achieve a less aggressive ventilation strategy. VT was reduced to 2-3 ml/kg, but oxygenation did not improve and airway pressures remained high. HFOV (8-10 Hz) was started using a recruitment strategy and oxygenation improved within 2 h. After 5 days, the patient was switched back to CV uneventfully and av-ECLA was removed after 8 days. CONCLUSION: The combination of two innovative treatment modalities resulted in rapid stabilization and improvement of gas exchange during severe ARDS refractory to conventional lung protective ventilation. During av-ECLA, extremely high oscillatory frequencies were used minimizing the risk of baro- and volutrauma.     

Differential lung ventilation in an infant using LMA and a long tracheal tube

This is a case report of differential lung ventilation in an infant using a conventional laryngeal mask airway (LMATM) and a commercially available longer paediatric tracheal tube. This 2-month-old infant had her left-sided congenital diaphragmatic hernia repaired on the sixth day of her life, and had been mechanically ventilated. The right middle lobe became grossly emphysematous and herniated into the left side of the chest, and the right lower lobe became totally atelectatic. A right middle lobe lobectomy was planned. To avoid hyperinflating the right middle lobe, and to expand the right lower lobe without providing a high airway pressure on the left lung, the dependent lung (i.e. left lung) was ventilated with an LMA, and the right lower lobe was expanded with a long tracheal tube inserted through the LMA via the swivel connector. This combination of a conventional LMA and a commercially available longer paediatric tracheal tube could be another way of providing differential ventilation in infants.     

Protective ventilation of patients with acute respiratory distress syndrome

The majority of patients with acute respiratory distress syndrome(ARDS) require mechanical ventilation. This support providestime for the lungs to heal, but the adverse effects of mechanicalventilation significantly influence patient outcome. Traditionally,these were ascribed to mechanical effects, such as haemodynamiccompromise from decreased venous return or gross air leaks inducedby large transpulmonary pressures. More recently, however, theARDS Network study has established the clinical importance oflowering the tidal volume to limit overdistension of the lungwhen ventilating patients with ARDS. This study suggests thatventilator-associated lung injury (VALI) caused by overdistensionof the lung contributes to the mortality of patients with ARDS.Moreover, the results from clinical and basic research haverevealed more subtle types of VALI, including upregulation ofthe inflammatory response in the injured and overdistended lung.This not only damages the lung, but the overflow of inflammatorymediators into the systemic circulation may explain why mostpatients who die with ARDS succumb to multi-organ failure ratherthan respiratory failure. The results of these studies, thepresent understanding of the pathophysiology of VALI, and protectiveventilatory strategies are reviewed. Br J Anaesth 2004; 92: 261–70     

Comparison of hemodynamic and respiratory effects of propofol and sevoflurane during carbon dioxide pneumoperitoneum in a swine model

The aim of this study was to compare intraoperative hemodynamic and respiratory parameters using propofol and sevoflurane during laparoscopic surgery in a porcine model. After induction of general anaesthesia in 16 pigs with fentanyl (0.005 mg kg(-1)) followed by propofol (6 mg Kg(-1)), it was maintained with fentanyl (0.01 mg kg(-1)h(-1)) and sevoflurane in O2 in group 1 (G1, n = 8) and fentanyl and propofol (12 mg kg(-1)h(-1)) in group 2 (G2, n = 8). The parameters monitored were heart rate, airway pressure (PAW), arterial and venous blood pressures and arterial blood gas analysis. The carbon dioxide pneumoperitoneum was maintained at 12 mmHg for 2 hours. Data were expressed as mean +/- standard deviation and were analysed using the Wilcoxon test (p < 0.05). G1 showed significantly higher PAW values than G2 at T60, T90 and T120. The heart rate values were significantly higher in G1 at T90 and T120. Middle arterial pressure was significantly lower in G1 than G2 at T30 and T60. The base deficit was significantly greater in G1 at T60, T90, T120 and Tpost. In this study propofol assured better hemodynamic and respiratory conditions than sevoflurane during laparoscopy in a porcine model.     

One lung ventilation in infants and children: experience with Marraro double lumen tube

BACKGROUND: Our objective was to evaluate the efficacy of selective bronchial intubation and independent lung ventilation during thoracic surgery in children up to 3 years, using a double lumen tube. METHODS: We studied retrospective (cases 1-6) and prospective cases (7-17) between January 1996 and December 2000 at the All India Institute of Medical Sciences, New Delhi, India and at Fatebenefratelli and Ophthalmiatric Hospital, Milan, Italy. Seventeen children, 1 day to 3 years of age and weighing 2.7-12 kg, were submitted to thoracic surgery for a variety of surgical conditions. Anesthesia was conducted as usual in this type of patient and selective intubation was performed using a double lumen tube (Marraro Pediatric double lumen tube). During the operation one lung ventilation was applied and at the end of surgery the collapsed lung was reexpanded independently from the contralateral lung. RESULTS: Six children remained intubated with a double lumen tube for between 8 and 48 h and one (case no. 11) with a single lumen tube for 24 h, while 10 of the older children were extubated on the table. No serious complications during or after surgery were noted and after extubation all the children recovered completely without sequelae. CONCLUSIONS: The double lumen tube appears to be very effective in allowing one lung ventilation in this age group during thoracic surgery.