Technology Development Standardization and Evaluation in Pulmonary Medicine

book chapterBiomedical Informatic

Lung function measured with SPECT in infants and children with bronchopulmonary dysplasia : correlation with respiratory management and clinical grading

Chronic lung disease, bronchopulmonary dysplasia (BPD) is a common and severe complication among extremely preterm born infants and infants with lung hypoplasia. Clinical grading of BPD is performed at 36 weeks postmenstrual age (or 56 days of age in moderately preterm infants) based on the need for supplemental oxygen. Oxygen requirement is a poor predictor for lung function in childhood and at adult age. We aimed to evaluate a lung function measurement for infants and children with BPD to complement clinical grading, evaluate the impact of respiratory management and standardize follow-up. No functional imaging of the lung in neonatal patients has been reported earlier. Single photon emission computed tomography (SPECT) is a technique that gives a functional imaging at a regional level within the lung. Previously the technique has not been available to use in non-cooperating patients that are small in body size. Recent technical advances and the development of a system for inhalation by our research group opened up the possibility of applying SPECT in neonatal patients. Our aim was to see if three different groups of patients, extremely/very preterm born infants, children with BPD or infants with congenital diaphragmatic hernia and lung hypoplasia, had lung function impairment with ventilation perfusion abnormalities within the lung. In paper I and IV we compare ventilation (V) perfusion (Q) matching with clinical severity grading, clinical characteristics and respiratory support during the first week of life (paper IV) and for the whole stay in the neonatal unit (paper I). V/Q abnormalities were correlated with BPD severity grade. Increasing days with mechanical ventilation (MV) were negatively correlated with lung function measured by SPECT. Higher values of carbon dioxide on the first day of life and during the first week were associated with better V/Q matching. High mean airway pressure (MAP) day 1 of life, a large decrease in MAP and early weaning of mechanical ventilation were also associated with better V/Q matching. High MAP and oxygen demand at day seven of life were associated with an increased severity grade of BPD. Additionally we found that one third of the patients graded as Mild or Moderate BPD had widespread V/Q abnormalities. In paper II we studied patients with lung hypoplasia and congenital diaphragmatic hernia. In this group, V/Q abnormalities were also associated with increasing days with MV but also increasing days with extracorporeal membrane oxygenation and persistence of pulmonary hypertension. In a follow-up study of 10-year-old children with BPD born preterm (paper III), we found less V/Q abnormalities than in the preterm infants but lower values of lung volume with good V/Q matching than expected in lung healthy children at that age. SPECT can be used as a measurement of lung function and evaluation of treatment in neonatal patients, infants and children and as a compliment to clinical grading and for follow- up of lung function in survivors with BPD. Ventilation perfusion matching abnormalities are common among patients with BPD both in the newborn period and at school age

Oxygen therapy in respiratory disorders

PhDOxygen therapy remains a cornerstone of medical practice and is generally regarded as being safe. However, there is a lack of clinical evidence to support the routine use of oxygen therapy, and in certain conditions, injudicious oxygen may cause harm. In this thesis, I will present two audits and three randomised controlled trials of oxygen therapy. Methods A prospective audit of the prescription and use of oxygen therapy before and after the introduction of an oxygen prescription section on a drug chart A retrospective audit of ambulance oxygen administration, in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) Two randomised controlled trials of high flow versus titrated oxygen in 150 patients with community acquired pneumonia and 106 patients with acute severe asthma A randomised controlled trial of 24 subjects with obesity hypoventilation syndrome (OHS) comparing 100% oxygen with air Results Oxygen prescription is suboptimal in hospital inpatients. Whilst an oxygen prescription section improved prescription, this intervention did not improve clinical practice Over 70% of patients presenting with AECOPD received high flow oxygen prior to presentation to the emergency department. The risk of adverse outcomes increased progressively with increased PaO2 High concentration oxygen leads to a rise in PaCO2 compared to titrated oxygen, when administered to patients presenting with asthma or pneumonia Breathing 100% oxygen leads to a rise in PaCO2 in patients with OHS Conclusion This series of studies has shown that further measures are warranted to ensure the safe practice of oxygen therapy in the pre-hospital and hospital setting. In addition, the findings suggest that the potential for high concentration oxygen therapy to increase PaCO2 is not limited to COPD but may occur in other respiratory conditions in which abnormal gas exchange or respiratory drive are present

Evaluation of Effect of Alveolar Recruitment Maneuver during Intraoperative Mechanical Ventilation

The study was conducted to evaluate the effect of alveolar recruitment maneuvers during intra operative mechanical ventilation. Forty patients of ASA I and II, posted for elective laparotomies were randomly allocated into two groups. In the study group, high positive end expiratory pressures for specified number of breaths were used to increase the peak inspiratory pressures. This increased airway pressure recruited the atelectatic alveoli .The recruited alveoli were prevented from collapsing by a baseline positive end expiratory pressure and repeated recruitment at regular intervals. No such recruitment strategies were employed in the control group. Proximal airway pressures and dynamic compliance significantly increased in the study group. (p <0.05). A significant increase in the arterial oxygen content was observed at 60 min in the study group. (PaO2/FiO2 ratio 581.05). But in the recovery room, the PaO2/FiO2 ratios in both the groups were comparable to the baseline. Hence, recruitment maneuvers increased the intra operative arterial oxygen content with not much effect in the post-operative period. CONCLUSION: General anesthesia comes hand in hand with atelectasis. Prevention of atelectasis not only increases arterial oxygenation but also reduces associated complications. This study concluded that alveolar recruitment maneuver significantly increased intra operative arterial oxygenation, which might be beneficial in preventing pulmonary complications and surgical site infections in the post-operative period