Lower FiO2 Research Articles

Thoracic Anesthesia: A Review of Current Topics and Debates

Thoracic anesthesia is a continually evolving field due to the development of new surgical and anesthetic technologies. Advances in lung isolation techniques, ventilation strategies, and postoperative pain management have improved patient outcomes. Airway management continues to progress as different devices provide advantages and disadvantages for lung isolation, surgical visualization, and access to the operative lung. Optimal ventilation strategies are moving toward lung protection, where oxygenation and ventilation are maintained with lower, more physiologic lung volumes with judicious use of alveolar recruitment, positive end-expiratory pressure, and lower FiO2. Neuraxial and regional anesthetics are the mainstays of postoperative analgesia, with adjuvants having roles in the acute period, but chronic post-thoracotomy pain remains challenging to treat. The role of perioperative inflammation has grown in importance, and volatile anesthetics have protective effects at the cellular and molecular levels, however the debate between the use of volatiles versus a total intravenous anesthetic technique continues.

Lung-Centered Open Heart Surgery: A Call for a Paradigm Change.

Lung-Centered Open Heart Surgery: A Call for a Paradigm Change.

Higher or lower oxygen for delivery room resuscitation of preterm infants below 28 completed weeks gestation: a meta-analysis

ObjectiveTo systematically review outcomes of infants ≤28+6 weeks gestation randomised to resuscitation with low (≤0.3) vs high (≥0.6) fraction of inspired oxygen (FiO2) at delivery.DesignSystematic review of randomised controlled trials...

Low Tidal Volume Ventilation Use in Acute Respiratory Distress Syndrome.

Low tidal volume ventilation lowers mortality in the acute respiratory distress syndrome. Previous studies reported poor low tidal volume ventilation implementation. We sought to determine the rate, quality, and predictors of low tidal volume ventilation use. Retrospective cross-sectional study. One academic and three community hospitals in the Chicago region. A total of 362 adults meeting the Berlin Definition of acute respiratory distress syndrome consecutively admitted between June and December 2013. Seventy patients (19.3%) were treated with low tidal volume ventilation (tidal volume < 6.5 mL/kg predicted body weight) at some time during mechanical ventilation. In total, 22.2% of patients requiring an FIO2 greater than 40% and 37.3% of patients with FIO2 greater than 40% and plateau pressure greater than 30 cm H2O received low tidal volume ventilation. The entire cohort received low tidal volume ventilation 11.4% of the time patients had acute respiratory distress syndrome. Among patients who received low tidal volume ventilation, the mean (SD) percentage of acute respiratory distress syndrome time it was used was 59.1% (38.2%), and 34% waited more than 72 hours prior to low tidal volume ventilation initiation. Women were less likely to receive low tidal volume ventilation, whereas sepsis and FIO2 greater than 40% were associated with increased odds of low tidal volume ventilation use. Four attending physicians (6.2%) initiated low tidal volume ventilation within 1 day of acute respiratory distress syndrome onset for greater than or equal to 50% of their patients, whereas 34 physicians (52.3%) never initiated low tidal volume ventilation within 1 day of acute respiratory distress syndrome onset. In total, 54.4% of patients received a tidal volume less than 8 mL/kg predicted body weight, and the mean tidal volume during the first 72 hours after acute respiratory distress syndrome onset was never less than 8 mL/kg predicted body weight. More than 12 years after publication of the landmark low tidal volume ventilation study, use remains poor. Interventions that improve adoption of low tidal volume ventilation are needed.

Failure of noninvasive ventilation in adult patients with acute asthma exacerbation.

Failure of noninvasive ventilation in adult patients with acute asthma exacerbation.

Effect of low inspired oxygen fraction on respiratory indices in mechanically ventilated horses anaesthetised with isoflurane and medetomidine constant rate infusion

Horses may become hypoxaemic during anaesthesia despite a high inspired oxygen fraction (FiO2). A lower FiO2 is used commonly in human beings to minimise atelectasis and to improve lung function, and previously has been shown to be of potential benefit in horses in experimental conditions. Other studies suggest no benefit to using a FiO2 of 0.5 during clinically relevant conditions; however, low FiO2 (0.65) is commonly used in practice and in a large number of studies. The present study was performed to compare the effect of a commonly used FiO2 of 0.65 versus 0.90 on calculated respiratory indices in anaesthetised mechanically ventilated horses in a clinical setting. Eighteen healthy Thoroughbred horses anaesthetised for experimental laryngeal surgery were recruited into a prospective, non-blinded, randomised clinical study. Before anaesthesia, the horses were randomly allocated into either low (0.65) or high (0.90) FiO2 groups and arterial blood gas (ABG) analysis was performed every 30 min during anaesthesia to allow for statistical analysis of respiratory indices. As expected, PaO2 was significantly lower in horses anaesthetised with a low FiO2, but was sufficient to fully saturate haemoglobin. There were no significant improvements in any of the other respiratory indices. There is no obvious benefit to be gained from the use of a FiO2 of 0.65 compared to 0.90 for mechanically ventilated Thoroughbred horses anaesthetised in lateral recumbency with isoflurane and a medetomidine constant rate infusion.

Is Salbutamol and Adrenalin Inhalation Effective in Management of Transient Tachypnia of Newborn?

Background: In the neonatal period, transient tachypnea of the newborn (TTN) is the most frequent cause of early respiratory distress because of delayed resorption of lung fluid, which fills the fetal airways. The inability of the lung to switch from fluid secretion to fluid absorption and immaturity in the expression of epithelial Nachannels (ENaC) may play an important role in the development of transient tachypnea of the newborn. Aims: Evaluation of inhalation therapy by BETA-2 agonist salbutamol and epinephrine for the management of transient tachypnea of newborn. Methods: The study was a prospective randomized control study. It included 60 neonates diagnosed clinically and radiologicaly as TTN. Inhaled salbutamol, epinephrine or saline 0.45% solution was administered. Results: Comparing studied groups after intervention, highly significant lower respiratory rate, TTN scores, respiratory support and duration of hospital stay was detected in group II (salbutamol group) while no significant difference between groups regarding heart rate after 4 hours from intervention. Original Research Article Nawar et al.; BJMMR, 14(3): 1-8, 2016; Article no.BJMMR.23922 2 Conclusion: Inhaled Salbutamol resulted in better outcome in decreasing the respiratory rate, TTN clinical score, lower FIO2, higher O2 saturation, decreasing the duration of respiratory support along with the total duration of hospitalization.

Evaluation of tissue hemoglobin saturation (StO2) using near-infrared spectroscopy during hypoxemia and hyperoxemia in Beagle dogs

ObjectiveTo determine the relationship between tissue oxygen saturation (StO2) and oxygen delivery ( D.O2) during hypoxemia and hyperoxemia. Study designProspective, randomized study. AnimalsEight purpose-bred Beagle dogs. MethodsDogs were anesthetized with isoflurane, ventilated to eucapnia, and instrumented for thermodilution cardiac output, invasive mean arterial pressure (MAP), sartorius muscle StO2 and airway gas monitoring. Dogs were administered rocuronium to facilitate mechanical ventilation and esmolol to minimize anesthetic effects on cardiac output. Instrumentation and baseline data collection were at 0.21 fractional inspired oxygen (FIO2). Dogs were evaluated at high (0.40 then 0.95) and low (0.15 then 0.10) FIO2 sequences in random order with a 60 minute rest period at FIO2 0.21 between sequences. Target FIO2 was achieved by manipulating nitrogen and oxygen flow rates. Data collected at each FIO2, after a 10 minute period of stabilization, included heart rate (HR), MAP, cardiac index (CI) and StO2. Arterial oxygen content (CaO2) and oxygen delivery index ( D.O2I) were calculated at each FIO2. Data analysis included Pearson’s correlation analysis and mixed-model anova (p < 0.05). ResultsThere were no significant differences in HR, MAP or CI across all FIO2 values. Significant decreases occurred in mean ± standard deviation StO2 (90 ± 4% to 69 ± 18%; p = 0.0001), D.O2I (458 ± 70 to 281 ± 100 mL minute−1 m−2; p = 0.0008) and CaO2 (13.2 ± 1.53 to 8.4 ± 2.05 mL dL−1; p = 0.0001) from FIO2 0.21 to 0.10, but not at remaining FIO2 values. The correlation between StO2 and D.O2I across all FIO2 values was strong (r = 0.97; p = 0.0013) and linear. Conclusions and clinical relevanceIn this model of hypoxemia and hyperoxemia, the strong correlation between StO2 and D.O2I suggests that StO2 can be used to estimate D.O2.

Standardisation of oxygen exposure in the development of mouse models for bronchopulmonary dysplasia.

ABSTRACTProgress in developing new therapies for bronchopulmonary dysplasia (BPD) is sometimes complicated by the lack of a standardised animal model. Our objective was to develop a robust hyperoxia-based mouse model of BPD that recapitulated the pathological perturbations to lung structure noted in infants with BPD. Newborn mouse pups were exposed to a varying fraction of oxygen in the inspired air (FiO2) and a varying window of hyperoxia exposure, after which lung structure was assessed by design-based stereology with systemic uniform random sampling. The efficacy of a candidate therapeutic intervention using parenteral nutrition was evaluated to demonstrate the utility of the standardised BPD model for drug discovery. An FiO2 of 0.85 for the first 14 days of life decreased total alveoli number and concomitantly increased alveolar septal wall thickness, which are two key histopathological characteristics of BPD. A reduction in FiO2 to 0.60 or 0.40 also caused a decrease in the total alveoli number, but the septal wall thickness was not impacted. Neither a decreasing oxygen gradient (from FiO2 0.85 to 0.21 over the first 14 days of life) nor an oscillation in FiO2 (between 0.85 and 0.40 on a 24 h:24 h cycle) had an appreciable impact on lung development. The risk of missing beneficial effects of therapeutic interventions at FiO2 0.85, using parenteral nutrition as an intervention in the model, was also noted, highlighting the utility of lower FiO2 in selected studies, and underscoring the need to tailor the model employed to the experimental intervention. Thus, a state-of-the-art BPD animal model that recapitulates the two histopathological hallmark perturbations to lung architecture associated with BPD is described. The model presented here, where injurious stimuli have been systematically evaluated, provides a most promising approach for the development of new strategies to drive postnatal lung maturation in affected infants.

Initial synchronized intermittent mandatory ventilation versus assist/control ventilation in treatment of moderate acute respiratory distress syndrome: a prospective randomized controlled trial.

Assist/control (A/C) ventilation may induce delirium in patients with acute respiratory distress syndrome (ARDS). We conducted a trial to determine whether initial synchronized intermittent mandatory ventilation with pressure support (SIMV + PS) could improve clinical outcomes in these patients. Intubated patients with moderate ARDS were enrolled and we compared SIMV + PS with A/C. Identical sedation, analgesia and ventilation strategies were performed. The co-primary outcomes were early (≤72 h) partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) and incidence of delirium. The secondary outcomes were all-cause in-hospital mortality, dosages of analgesics and sedatives, incidence of patient-ventilator asynchrony, and duration of mechanical ventilation and hospital stay. We screened 2,684 patients and 40 patients were enrolled in our study. In SIMV + PS, early (≤72 h) PaO2/FiO2 was greater improved than that at baseline and that in A/C (P<0.05) with lower positive end-expiratory pressure (PEEP) (8.7±3.0 vs. 10.3±3.2, P<0.001) and FiO2 (58%±18% vs. 67%±19%, P<0.001). We found more SIMV + PS success (defined as SIMV + PS successfully applied without switching to A/C) (100.0% vs. 16.7%, P<0.001), less male (46.3% vs. 85.7%, P=0.015) and pulmonary etiology of ARDS (53.8% vs. 92.9%, P=0.015), and lower PEEP (9.1±3.1 vs. 10.3±3.3, P=0.004) and FiO2 (58%±19% vs. 71%±19%, P<0.001) in survival patients. However, there were no significant differences in incidence of delirium and mortality, dosages of analgesics and sedatives, incidence of patient-ventilator asynchrony, duration of mechanical ventilation and hospital stay (P>0.05). In patients with moderate ARDS, SIMV + PS can safely and effectively improve oxygenation, but does not decrease mortality, incidence of delirium and patient-ventilator asynchrony, dosages of analgesics and sedatives, and duration of mechanical ventilation and hospital stay.

Conservative oxygen therapy in mechanically ventilated patients following cardiac arrest: A retrospective nested cohort study

BackgroundIn mechanically ventilated (MV) cardiac arrest (CA) survivors admitted to the intensive care unit (ICU) avoidance of hypoxia is considered crucial. However, avoidance of hyperoxia may also be important. A conservative approach to oxygen therapy may reduce exposure to both. MethodsWe evaluated the introduction of conservative oxygen therapy (target SpO2 88–92% using the lowest FiO2) during MV for resuscitated CA patients admitted to the ICU. ResultsWe studied 912 arterial blood gas (ABG) datasets: 448 ABGs from 50 ‘conventional’ and 464 ABGs from 50 ‘conservative’ oxygen therapy patients. Compared to the conventional group, conservative group patients had significantly lower PaO2 values and FiO2 exposure (p<0.001, respectively); more received MV in a spontaneous ventilation mode (18% vs 2%; p=0.001) and more were exposed to a FiO2 of 0.21 (19 vs 0 patients, p=0.001). Additionally, according to mean PaO2, more conservative group patients were classified as normoxaemic (36 vs 16 patients, p<0.01) and fewer as hyperoxaemic (14 vs 33 patients, p<0.01). Finally, ICU length of stay was significantly shorter for conservative group patients (p=0.04). There was no difference in the proportion of survivors discharged from hospital with good neurological outcome (14/23 vs 12/22 patients, p=0.67). ConclusionsOur findings provide preliminary support for the feasibility and physiological safety of conservative oxygen therapy in patients admitted to ICU for MV support after cardiac arrest (Trial registration, NCT01684124).

Cerebral oxygenation following preterm delivery

The Neonatal Resuscitation Program (NRP) has progressed over 25 years from assumptions and professional opinion about resuscitation of the term infant to evidence-based recommendations for the initial support of both term and preterm infants. This evidence base has been developed by interested investigators using traditional and newer monitoring techniques to measure the transitions in oxygenation, cardiopulmonary function, and metabolism following birth. Supplemental oxygen can cause oxidant exposures that may cause long-term organ injury. As the monitoring has improved, the challenges are to learn if monitoring can change outcomes rather than simply improve physiologic variables that may not impact long-term outcomes. The report by Kenosi et al illustrates this point. They evaluated cerebral oxygenation immediately following delivery of preterm infants with the hypothesis that those infants that received >30% oxygen would have more brain regional oxygen saturations >85% and, thus, the possibility of oxidant injury relative to infants receiving <30%. They found no difference in >85% saturation values between the groups, but more of the infants receiving >30% oxygen had saturations <55%, indicating brain hypoxia. The infants requiring more oxygen had more lung immaturity and presumably a less mature cardiovascular adaptation to birth. This report demonstrates interesting but transient differences in cerebral oxygen saturations. But, the bigger challenge will be to evaluate if the differences are clinically relevant and if measurements of cerebral oxygen saturation are of value during delivery, beyond experimental studies. The physiology is fascinating, and more studies are required to identify which measurements can improve outcomes.Article page 1007▶ The Neonatal Resuscitation Program (NRP) has progressed over 25 years from assumptions and professional opinion about resuscitation of the term infant to evidence-based recommendations for the initial support of both term and preterm infants. This evidence base has been developed by interested investigators using traditional and newer monitoring techniques to measure the transitions in oxygenation, cardiopulmonary function, and metabolism following birth. Supplemental oxygen can cause oxidant exposures that may cause long-term organ injury. As the monitoring has improved, the challenges are to learn if monitoring can change outcomes rather than simply improve physiologic variables that may not impact long-term outcomes. The report by Kenosi et al illustrates this point. They evaluated cerebral oxygenation immediately following delivery of preterm infants with the hypothesis that those infants that received >30% oxygen would have more brain regional oxygen saturations >85% and, thus, the possibility of oxidant injury relative to infants receiving <30%. They found no difference in >85% saturation values between the groups, but more of the infants receiving >30% oxygen had saturations <55%, indicating brain hypoxia. The infants requiring more oxygen had more lung immaturity and presumably a less mature cardiovascular adaptation to birth. This report demonstrates interesting but transient differences in cerebral oxygen saturations. But, the bigger challenge will be to evaluate if the differences are clinically relevant and if measurements of cerebral oxygen saturation are of value during delivery, beyond experimental studies. The physiology is fascinating, and more studies are required to identify which measurements can improve outcomes. Article page 1007▶ Effects of Fractional Inspired Oxygen on Cerebral Oxygenation in Preterm Infants following DeliveryThe Journal of PediatricsVol. 167Issue 5PreviewTo explore regional cerebral oxygen saturations (rcSO2) in preterm neonates initially stabilized with 0.3 fractionated inspired oxygen (FiO2) concentrations. We hypothesized that those infants who received >0.3 FiO2 during stabilization following delivery would have relatively higher rcSO2 postdelivery compared with those stabilized with a lower FiO2. Full-Text PDF

Ventilatory support of patients with sepsis or septic shock in resource-limited settings.

In this chapter we discuss recommendations on the identification of patients with acute respiratory distress syndrome (ARDS), indications for mechanical ventilation, and strategies for lung-protective ventilation in resource-limited settings. Where blood gas analyzers are unavailable, it can be replaced by the plethysmographic oxygen saturation/fractional inspirational oxygen concentration (SpO2/FiO2) gradient. Bedside lung ultrasound is a valuable diagnostic tool assessing pulmonary edema and other pathologies. A number of recommendations for safe and lung-protective mechanical ventilation in patients with sepsis and respiratory failure are provided. However, many of these have not been trialed specifically in resource-limited settings. These recommendations include an elevated head-of-bed position and a minimum level of positive end-expiratory pressure (PEEP) of 5 cm H2O only to be in patients with moderate or severe ARDS. In addition, low FiO2 and low oxygenation goals are suggested, using PEEP/FiO2 tables. Recruitment maneuvers are indicated in refractory hypoxia, but require experienced staff. Low tidal volumes (5–7 ml/kg predicted body weight, avoiding >10 ml/kg) are recommended and if at all possible in combination with end-tidal carbon dioxide (CO2) monitoring for recognition of dislodgement of the endotracheal tube and under- or overventilation. “Volume-controlled” modes could be safer than “pressure-controlled” modes, and we recommend to check regularly whether a patient tolerates a “support” mode; we also suggest to perform spontaneous breathing trials to timely identify patients who are ready for extubation, but also to plan extubating patients when sufficient staff is around to guarantee safe re-intubation.

Effects of Fractional Inspired Oxygen on Cerebral Oxygenation in Preterm Infants following Delivery

To explore regional cerebral oxygen saturations (rcSO2) in preterm neonates initially stabilized with 0.3 fractionated inspired oxygen (FiO2) concentrations. We hypothesized that those infants who received >0.3 FiO2 during stabilization following delivery would have relatively higher rcSO2 postdelivery compared with those stabilized with a lower FiO2. A single center prospective observational study of 47 infants born before 32 weeks. Using near infrared spectroscopy, rcSO2 values were recorded immediately after birth. All preterm infants were initially given 0.3 FiO2 and were divided into 2 groups according to subsequent FiO2 requirements of either ≤0.3 or >0.3 FiO2. Using a mixed-effects model, we compared the difference between the groups over time. Also, the area measures below 55% (hypoxia) and above 85% (hyperoxia) were compared between the groups. The mean (SD) gestation was 29.4 (1.6) weeks and the mean (SD) weight was 1.3 (0.4) kg. Less than one-half of the infants (20/45; 43%) required ≤0.3 FiO2. In the delivery suite, the median (IQR) rcSO2 in the low and high FiO2 groups were 81% (66%-86%) and 72% (62%-86%), respectively. Patients in the high FiO2 group had a larger rcSO2 area below 55% (P = .01). There was a significant difference in rcSO2 between the groups (P < .05), with the low group having higher rcSO2 values initially, but this difference changed over time. In the neonatal intensive care unit (NICU), rcSO2 values were lower by 7.1% (CI 12.13 to 2.06%) P = .008 in the high FiO2 group. Infants given >0.3 FiO2 had more cerebral hypoxia than infants requiring ≤0.3 FiO2 but no difference in the degree of cerebral hyperoxia, both in the delivery suite and the NICU. This suggests that a more rapid increase in oxygen titration maybe be required initially for preterm infants.

Application of airway pressure release ventilation in severe pneumonia-related acute respiratory distress syndrome in children

Objective To investigate the effects of airway pressure release ventilation (APRV) in children with severe pneumonia-related acute respiratory distress syndrome(ARDS). Methods Ten children suffering severe pneumonia-related ARDS with APRV were included in Pediatric Intensive Care Unit, Beijing Children's Hospital, Capital Medical University from March 2011 to October 2014.Ventilation variables, changes of airway pressure and Ramsay scores were collected and compared with that in conventional ventilation (CV). Clinical variables were mea-sured at CV before APRV and at 1, 4, 12, 24 hours after transition to APRV. Results High airway pressure(Phigh) at each time point during APRV was significantly lower than peak airway pressure(Ppeak) or plateau airway pressure(Pplat) in CV[(26.00±2.94) cmH2O(1 cmH2O=0.098 kPa), (24.40±3.34) cmH2O, (23.30±3.46) cmH2O, (23.00±3.80) cmH2O vs (31.80±5.59) cmH2O, P<0.01]. Mean airway pressure(Pmean) at each time point during APRV was significantly higher than that in CV[(23.00±2.86) cmH2O, (21.69±3.12) cmH2O, (20.89±3.31) cmH2O, (20.46±3.48) cmH2O vs (17.50±2.37) cmH2O, P<0.05]. Fraction of inspired oxygen(FiO2) were significantly decreased at 4, 12 and 24 hours after APRV than that in CV[(73.00±22.39)%, (63.50±20.16)%, (63.00±21.11)% vs (88.00±15.49)%, P<0.05]. Ramsay scores were significantly decreased at each time point during after APRV than that in CV[(3.90±0.74) scores, (2.90±0.88) scores, (3.00±1.15) scores, (3.50±0.71) scores vs (4.60±0.52) scores, P<0.05]. Conclusions Compared with CV, APRV had a lower Phigh and FiO2, a higher Pmean and more shallow sedation.APRV may be an effective ventilation mode in children's severe pneumonia-related ARDS. Key words: Airway pressure release ventilation; Child; Acute respiratory distress syndrome; Mechanical ventilation

Less Oxygen, Later Intubation and Reduced Respiratory Pressures for ELBW Infants from 1997 to 2011.

Evidence concerning delivery room management in extremely low birth weight infants (ELBW) has grown substantially within the last 20 years, leading to several guidelines and recommendations. However, it is unknown in which extent local treatment strategies have changed and if they reflect current recommendations. A detailed questionnaire about treatment strategies for ELBW infants was sent to all German neonatal intensive care units (NICUs) treating ELBW infants in 1997. A follow-up survey was conducted in 2011 and sent to all NICUs in Germany, Austria and Switzerland. RESULTS on delivery room management were compared to the first survey. In 1997 and 2011, 63.6 and 66.2% of the approached hospitals responded. In 2011 similar results were observed between university and non-university hospitals as well as NICUs of different size. Differences between Germany, Austria and Switzerland were minimal. Changes over time were a lower initially applied fraction of inspired oxygen (FiO2) and peak inspiratory pressure (PiP) in 2011 compared to 1997. A longer time of apnea was tolerated before tracheal intubation is performed; the time of apnea was less frequently a sole criterion for intubation and surfactant was applied at lower FiO2 in 2011. The time of no thorax excursions and transport of the infant were considered an indication for intubation in 30.2 and 22.5%, and did not change in the observation period. Treatment strategies for delivery room management in ELBW infants changed significantly between 1997 and 2011 and largely reflect current recommendations.

The Cause of Acute Respiratory Failure Predicts the Outcome of Noninvasive Ventilation in Immunocompromised Children.

Noninvasive ventilation (NIV) may be superior to conventional therapy in immunocompromised children with respiratory failure. Mortality, success rate, prognostic factors and side effects of NIV for acute respiratory failure (ARF) were investigated retrospectively in 41 in children with primary immunodeficiency, after stem cell transplantation or chemotherapy for oncologic disease. In 11/41 (27%) children invasive ventilation was avoided and patients were discharged from ICU. In children with NIV failure ICU-mortality was 19/30 (63%). 8/11 (72%) children with NIV success had recurrence of ARF after 27 days. Only 4/11 (36%) children with first episode NIV success and 8/30 (27%) with NIV failure survived to hospital discharge. Lower FiO2, SpO2/FiO2 and blood culture positive bacterial sepsis were predictive for NIV success, while fungal sepsis or culture negative ARF were predictive for NIV failure. We observed catecholamine treatment in 14/41 (34%), pneumothorax in 2/41 (5%), mediastinal emphysema in 3/41 (7%), a life threatening nasopharyngeal hemorrhage and need for resuscitation during intubation in 5/41 (12%) NIV-episodes. The prognosis of ARF in immunocompromised children remains guarded independent of initial success or failure of NIV due to a high rate of recurrent ARF. Reversible causes like bacterial sepsis had a higher NIV response rate. Relevant side effects of NIV were observed.

Anaesthesia for repair of anomalous origin of left coronary artery from pulmonary artery.

Sir, Anomalous origin of left coronary artery from pulmonary artery (ALCAPA) is a rare congenital heart defect (1 in 3,00,000 live births), in which left coronary artery arises from pulmonary artery, instead of branching from the aorta.[1,2,3] A 35-year-old, 47 kg female was scheduled for corrective surgical repair of ALCAPA. For the previous 2 years, she had progressively increasing breathlessness and anginal attacks on exertion. The 12 lead electrocardiograms (ECG) revealed sinus rhythm, without any ST or T wave changes. Transthoracic echocardiography revealed mild left ventricular enlargement and normal ejection fraction of 55%, without any regional wall motion abnormalities. The coronary angiography revealed ALCAPA. Her medications included enalapril, digoxin and furosemide. In the operation theatre, after securing a 16 gauge intravenous (IV) cannula, monitoring with ECG, non-invasive blood pressure (BP), cardiac output (CO) and oxygen saturation (SpO2) was started. The left femoral artery and left radial artery were cannulated for invasive BP monitoring. General anaesthesia was induced and trachea intubated using fentanyl 100 μg, morphine 6 mg, midazolam 2 mg, etomidate 6 mg and vecuronium 8 mg (all administered IV). Right internal jugular vein was cannulated, and anaesthesia was maintained using oxygen/air/isoflurane, with infusions of rocuronium and fentanyl. The ventilatory settings were aimed to prevent hypocarbia, hyperoxia and alkalosis. A low FiO2 of 0.4 was used to maintain a high pulmonary vascular resistance (PVR). The end-tidal CO2 was maintained between 40 and 42 mmHg, and partial pressure of oxygen was monitored. The surgery was performed under cardiopulmonary bypass (CPB). Dopamine (5 μg/kg/min) was used during weaning of the patient from CPB. Intra-operatively and post-operatively, patient remained haemodynamically stable. The survival of neonates with ALCAPA varies with the adequacy of left ventricular perfusion. This depends on the inflow of blood to left coronary artery via collaterals from right coronary artery (RCA) and the proportion of coronary steal from left coronary artery to the pulmonary artery. Only 10-20% of these neonates survive till adulthood.[4] In the post-natal period, there is a decrease in pulmonary vascular resistance (PVR) and oxygen content of the pulmonary blood. This can reverse the direction of blood flow from left coronary artery to the pulmonary artery (coronary steal phenomenon). This causes hypo-perfusion of the left ventricular myocardium by relatively de-saturated blood, leading to myocardial ischaemia. This can lead to mitral valve insufficiency.[5,6] Patients might have accompanying atrial septal defect, ventricular septal defect, patent ductus arteriosus, tetralogy of Fallot or coarctation of the aorta. All these factors precipitate congestive heart failure in 80–90% of these infants. These neonates present with tachypnoea, tachycardia, poor feeding, irritability and diaphoresis. They can survive till adulthood, due to well-developed collaterals from RCA, which provides adequate perfusion to the left ventricle. The RCA was dilated and tortuous in this patient [Figure 1]. The coronary angiogram is the gold standard investigation for diagnosis of ALCAPA. The adults present with exertional dyspnoea, angina and cardiac arrhythmias.[2] Diuretics and inotropes are used for the management of congestive heart failure. Figure 1 Dilated and tortuous right coronary artery The anaesthetic goals are to (1) maintain optimum preload, (2) prevent a decrease in PVR, (3) maintain myocardial contractility, (4) maintain low or normal systemic vascular resistance (SVR) and (5) prevent tachycardia. The preload is optimized to ensure an adequate CO. In these patients, the stroke volume is monitored instead of CO, because CO varies with heart rate. The laryngoscopy/intubation should be smooth and rapid. Swings in heart rate and BP are avoided. Tachycardia is detrimental, as it can alter the myocardial oxygen supply/demand ratio and predispose to myocardial ischaemia. Etomidate being haemodynamically stable is preferred for induction of anaesthesia. Isoflurane is the inhalational agent of choice, as it causes less myocardial depression, compared with halothane or sevoflurane and is a better myocardial protective agent. Low PVR will accentuate the coronary steal phenomenon. The presence of hypocarbia, hyperoxia or alkalosis decreases PVR and is detrimental. They are ventilated using oxygen/air mixture, and partial pressure of oxygen is not allowed to rise very high. A higher end-tidal CO2 is maintained to achieve a higher PVR. A low afterload SVR is maintained, for an adequate stroke volume. Aggressive reduction of afterload may also be deleterious, as it attenuates the perfusion of RCA, thus decreasing the blood flow to left coronary artery. Inotropes such as dopamine, dobutamine or milrinone should be used cautiously, as they increase the consumption of myocardial oxygen, which may accentuate myocardial ischemia. Thus, patients with ALCAPA repair can be managed successfully, after understanding the pathophysiological changes.

Mechanical ventilation in chest trauma.

Traumatic chest injury is one the most important factors for total morbidity and mortality in traumatized emergency patients (1). Chest trauma is the cause of 20% to 25% of the trauma-related deaths per year in the United States and is the leading cause of death in the first four decades of life (2). Traumatic chest injuries often occur in combination with other severe injuries, such as head, brain, extremity and abdominal injuries (3). Traumatic chest trauma can occur after car and motor accident, assaults, falls and explosive blasts via a variety of different mechanisms. Overall, car and motor accidents account for 70% to 80% of all thoracic injuries (4). Traumatic chest lesion can lead to conditions like pulmonary contusion pneumothorax, flail chest, bronchopleural fistula, and tracheobronchial rupture. One of the most frequent intrathoracic injuries is lung contusion that results from blunt chest trauma. Particularly, in patients with multiple traumas, severe blunt chest injuries and especially pulmonary contusions may deteriorate the patients’ outcome due to increased morbidity and mortality. Parenchymal lung injuries, such as pulmonary contusion, may require support of oxygenation and ventilation through mechanical ventilation strategies. The majority of traumatic chest injuries can be treated with careful observation or minor surgery such as tube thoracostomy. Among the patients of traumatic chest injuries 12% to 15% of them will require thoracotomy. In patients with impaired gas exchange, endotracheal intubation and mechanical ventilation are essential. Moreover, further pulmonary complications such as acute respiratory distress syndrome (ARDS) and respiratory failure can be prevented by early fixation of concomitant long-bone fractures. Ventilation in traumatic chest patients may remain a challenge due to complexity in obtaining balance between sufficient ventilation and prevention of further harm to the lungs. The goal of ventilation in this condition is protective lung ventilation with low FiO2, plateau pressure, and using reduced tidal volumes to protect the lungs from further injury (1). The tidal volume should be limited to less than 6 mL/kg of ideal body weight and plateau pressure to 12 cm H2O is required, invasive positive-pressure ventilation (IPPV) should be considered.

Application of lung recruitment maneuver in preterm infants with respiratory distress syndrome ventilated by proportional assist ventilation

To understand the effect of lung recruitment maneuver (LRM) with positive end-expiratory pressure (PEEP) on oxygenation and outcomes in preterm infants with respiratory distress syndrome (RDS) ventilated by proportional assist ventilation (PAV). From January 2012 to June 2013, thirty neonates with a diagnosis of RDS who required mechanical ventilation were divided randomly into LRM group (n=15, received an LRM and surport by PAV) and control group (n=15, only surport by PAV). There were no statistically significant differences in female (7 vs. 6); gestational age [(29.3±1.2) vs. (29.5±1.1) weeks]; body weight[(1,319±97) vs. (1,295±85) g]; Silverman Anderson(SA) score for babies at start of ventilation (7.3±1.2 vs. 6.9±1.4); initial FiO2 (0.54±0.12 vs. 0.50±0.10) between the two groups (all P>0.05). LRM entailed increments of 0.2 cmH2O (1 cmH2O=0.098 kPa) PEEP every 5 minutes, until fraction of inspired oxygen (FiO2)=0.25. Then PEEP was reduced and the lung volume was set on the deflation limb of the pressure/volume curve.When saturation of peripheral oxygen fell and FiO2 rose, we reincremented PEEP until SpO2 became stable. The related clinical indicators of the two group were observed. The doses of surfactant administered (1.1±0.3 vs. 1.5±0.5, P=0.027), Lowest FiO2 (0.29±0.05 vs. 0.39±0.06, P=0.000), time to lowest FiO2[ (103±18) vs. (368±138) min, P=0.000] and O2 dependency [(7.6±1.0) vs.( 8.8±1.3) days, P=0.021] in LRM group were lower than that in control group (all P<0.05). The maximum PEEP during the first 12 hours of life [(8.4±0.8) vs. (6.8±0.8) cmH2O, P=0.000] in LRM group were higher than that in control group (P<0.05). FiO2 levels progressively decreased (F=35.681, P=0.000) and a/AO2 Gradually increased (F=37.654, P=0.000). No adverse events and no significant differences in the outcomes were observed. LRM can reduce the doses of pulmonary surfactant administered, time of the respiratory support and the oxygen therapy in preterm children with RDS.