Patterns of spirometry findings among patients with suspected lower airway obstruction in a tertiary hospital, South-South, Nigeria

Objectives: The respiratory system consists of the upper airway and the lower airway. Although, the airway sub-serves several functions, the most important functions of the airway are ventilation and gas exchange. Lower airway obstruction by diseases such as Asthma and COPD may impair airway function. Spirometry is a useful tool in the assessment of airway function. We aim to describe the observed patterns of spirometry findings among patients with suspected lower airway obstruction at the Niger Delta University Teaching Hospital (NDUTH), Okolobiri, South-South Nigeria. Methods: Across-sectional study. Records of spirometry values were used to assess spirometry patterns. IBM SPSS software was used to analyze data. Results: Spirometry records of a total 100 patients were analysed. Mean age was 48.90 ± 19.77 years. There were 59% males and 41% of females. Spirometry patterns were: normal-59%; obstructive-39%; restrictive-1%; mixed-1%. Conclusion: Spirometry is a useful non-invasive tool in the diagnosis of respiratory diseases, and recommended for patient evaluation in every tertiary hospital in Nigeria. Keywords: Spirometry pattern, airway obstruction, asthma, COPD

Respiratory Acidosis in the Intensive Care Unit

This chapter explains that the interpretation of acid–base abnormalities is an essential skill required when caring for critically ill patients. The differential causes of respiratory acidosis include central nervous system depression, upper and lower airway obstruction, and hypermetabolic states with increased production of CO2, such as malignant hyperthermia and thyroid storm. The treatment for hypoxic and hypercarbic respiratory failure involves reversing the offending agents if applicable, treatment of the underlying cause, and mechanical ventilation. The 2 commonly used strategies for mechanical ventilation are non-invasive ventilation with a mask and endotracheal intubation. The selection of ventilation strategy is dependent on numerous patient factors. Clinicians must set respiratory rate, tidal volume, positive end-expiratory pressure, inspiratory flow, fraction of inspired oxygen, mode (volume versus pressure control), and the amount of assistance per breath. All need to be tailored toward each patient’s specific goals. In patients with severe acidosis, there may be a temptation to hyperventilate in order to treat the hypercarbia and hypoxia as quickly as possible. This can be deleterious as high tidal volumes may lead to ventilator-induced lung injury due to volutrauma, cytotrauma, and barotrauma.

Impact of Helium-Oxygen Administered via High Velocity Nasal Insufflation on Delivery of Inhaled Nitric Oxide

Inhaled nitric oxide (iNO) may be continued during the transition from invasive to noninvasive respiratory support. Upper airway obstruction from laryngeal edema following extubation and lower airway obstruction from asthma and bronchiolitis may be managed with inhaled helium. The coadministration of helium with iNO and the impact on delivered amounts of iNO have not been extensively studied. A bench model simulating a spontaneously breathing infant received iNO at varying preset doses delivered with either helium-oxygen or nitrogen-oxygen via a Vapotherm unit. iNO levels were measured at the simulated trachea. Results from the two conditions were compared using t-tests. When nitrogen-oxygen was used, there was no difference between preset and measured iNO levels. A significant difference was present when helium-oxygen was used, with a 10-fold increase in measured iNO levels compared with preset values. The use of helium resulted in a significant increase in measured iNO at the level of the simulated trachea. Clinicians must be aware that iNO will not be delivered at prescribed doses when used with helium under the conditions used in this study.

Elective Use of Veno-venous Extracorporeal Membrane Oxygenation and High-flow Nasal Oxygen for Resection of Subtotal Malignant Distal Airway Obstruction

We describe the use of peripheral veno-venous extracorporeal membrane oxygenation (VV ECMO) and high-flow nasal oxygen as procedural support in a patient undergoing debulking of a malignant tumour of the lower airway. Due to the significant risk of complete airway obstruction upon induction of anaesthesia, ECMO was established while the patient was awake, and was maintained without systemic anticoagulation to minimise the risk of intraoperative bleeding. This case illustrates that ECMO support with high-flow nasal oxygen can be considered as part of the algorithm for airway management during surgery for subtotal lower airway obstruction, as it may be the only viable option for maintaining adequate gas exchange.