Table of Content - Volume 6 Issue 2 - May 2017
Indications for invasive and non-invasive mechanical ventilator in patients of respiratory failure
Gajanan Vaijnath Halkanche1, Fazlullah Hashmi2*
1Associate Professor, Department of Medicine, Government Medical College, Latur, Maharashtra, INDIA. 2Assistant Professor, Department of Chest and TB, DR Shankarrao Chavan Government Medical College, Nanded, Maharashtra, INDIA. Email: gajananhalkanche@rediffmail.com
Abstract Background: Patients who developed respiratory failure had to be put on invasive mechanical ventilation in spite of known impending severe complications. Recently, physicians are using non-invasive ventilation for patients with respiratory failure of varied etiology. Aim: To study the indications for invasive and non-invasive mechanical ventilator in patients of respiratory failure. Material and Methods: A total of 216 critically ill Patients admitted in intensive respiratory care unit (IRCU) who developed respiratory failure due to various conditions and diseases were studied for the indications of invasive and non invasive ventilations. Results: Amongst 216 patients, 182 (84.2%) required invasive and 34 (15.7%) required noninvasive ventilator. Out of 182 with invasive ventilator, 138 (75.8%) were of acute respiratory failure (poisoning, ARDS, snake bite). Common indications of noninvasive ventilator was COPD (81%) followed by bronchial asthma (80%). Conclusion: Invasive mechanical ventilation is more commonly used in acute respiratory failure patients including poisoning (organophosphate and related compound), ARDS and snake bite (neuroparalytic), whereas, noninvasive mechanical ventilation is commonly used in patients of acute exacerbation of COPD and bronchial asthma. Key Words: Respiratory failure, mechanical ventilation, invasive ventilator, non invasive ventilator, indications.
INTRODUCTION The respiratory system consists of two parts viz., the gas exchange system (lungs) and the ventilating system (respiratory pump). These can be impaired independently. In pulmonary failure, oxygen therapy is sufficient unless it is accompanied by severe impairment of the gas exchange process, which would then additionally require the application of positive airway pressure. In contrast, dysfunction within the ventilatory system primarily requires mechanical ventilation.1 Patients can get into critical care unit (CCU) because of respiratory failure secondary to pulmonary pathology like pneumonia, status asthmaticus, pulmonary oedema, in many other patients, respiratory failure is secondary to sepsis, cardiac failure or neurological disorders. Mechanical ventilation is indicated when the patient's respiration is inadequate to maintain adequate ventilation. It is also indicated as prophylaxis for imminent collapse of other physiologic functions, or ineffective gas exchange in the lungs.2,3 Noninvasive ventilation (NIV) refers to positive pressure ventilation delivered through a noninvasive interface (nasal mask, facemask, or nasal plugs), rather than an invasive interface (endotracheal tube, tracheostomy). Its use has become more common as its benefits are increasingly recognized.4,5 The present study was carried out to study the indications for invasive and non-invasive mechanical ventilator in patients of respiratory failure.
MATERIAL AND METHODS This prospective observational study was conducted in the intensive respiratory care unit (IRCU) of a tertiary referral and teaching hospital. All critically ill patients admitted to the intensive care unit with respiratory failure during the prescribed study period were considered for case identification. The present study was approved by the institute ethics committee. Inclusion Criteria Acute respiratory failure or impending respiratory failure due to:
Exclusion Criteria
Methodology: All included patients were evaluated on the basis of clinical parameters, oxygen saturation monitoring on pulse oximetry to determine the need for mechanical ventilation include following:6,7 Acute Respiratory Failure: At least two of the following criteria should be present:
Chronic Respiratory Failure (Obstructive lung disease)
Relevant investigations were done in patients on mechanical ventilation in critical care unit. They included complete heamogram including hemoglobin%, complete blood count, Kidney function test, Liver function tests, X-ray chest PA view, ECG, Endotracheal aspirate for culture and sensitivity, Serum electrolyte and Arterial blood gas analysis. In selected cases, whenever necessary specific investigations such as, Sputum for AFB, Blood culture, CSF examination and CT scan (Brain). Procedure of intubation:8 Based upon anatomical considerations commonly employ the Mallampati scale to evaluate objectively the airway’s suitability for placement of the endotracheal tube. The ability to visualize the soft palate, fauces, tonsillar pillars, and uvula is used to predict the degree of difficulty in exposing the larynx. Prerequisites for invasive ventilator support via endotracheal tube or tracheostomy tube:6
Prerequisites for non-invasive ventilation:6
The recommended initial ventilator settings follow. Adjustments in these ventilator settings may be made according to the patient's clinical situation.
Table 1: Initial ventilator settings on invasive mechanical ventilation: 6
Initial Ventilatory Settings of NIVV:15
RESULTS A total of 216 critically ill Patients admitted in intensive respiratory care unit (IRCU) who developed respiratory failure due to various conditions and diseases were studied for the indications of invasive and non invasive ventilations. Amongst 216 patients of respiratory failure, 135 were male (62.5%) and 81 were female (37.5%). Distribution of patients according to underlying disorder who required mechanical ventilation is shown in Table 2.
Table 2: Disease distribution of patients requiring mechanical ventilation
Amongst overall 216 patients, common indications for initiation of mechanical ventilation included acute respiratory failure 69.4%, acute exacerbation of chronic respiratory failure 13.4%, coma 12.5%, neuromuscular disease 2.8% and 1.9% were other miscellaneous conditions.
Table 3: Indications for invasive mechanical ventilator in studied patients
Amongst 216 patients, 182 (84.2%) required invasive ventilator. Maximum patients i.e., 138 (75.8%) were of acute respiratory failure (poisoning, ARDS, snake bite).
Table 4: Indications for noninvasive mechanical ventilator in studied patients
Amongst 216 patients of respiratory failure, 34 patients (15.7%) required noninvasive ventilator. Common indications of noninvasive ventilator in present study group was COPD (81%), Bronchial asthma (80%), Tuberculous destroyed lung (33.3%) and ARDS (27.3%).
DISCUSSION For many years, patients who developed respiratory failure had to be put on invasive mechanical ventilation in spite of known impending severe complications. Recently, numerous randomized controlled trials have been carried out on use of non-invasive ventilation (NIV) for patients with respiratory failure of varied etiology, such as, acute exacerbation of chronic obstructive pulmonary disease (COPD), acute cardiogenic pulmonary oedema, hypoxaemic respiratory failure and as an adjunct to weaning patients.9,10 Nowadays, physicians have started to use NIV in patients with respiratory failure as much as possible instead of mechanical ventilation to avoid its complications. In the present study, amongst the total 216 patients, 182 (84.2%) required invasive ventilator. Maximum patients i.e., 138 (75.8%) were of acute respiratory failure (poisoning, ARDS, snake bite). In a study done by Schettino et al,11 for patients with cardiogenic pulmonary edema, acute exacerbation of chronic obstructive pulmonary disease (COPD), acute hypercapnic respiratory failure, post extubation respiratory failure patients and acute hypoxemic respiratory failure, intubation rate was 18%, 24%, 38%, 40% and 60%, respectively. Phua J et al.12 reported that risk of NIV failure was lower in COPD than in other condition (19% vs. 47%) respectively. In a study by Gosavi Rakhi A et al,13 out of 110 patients 22 (20%) patients required invasive ventilation, out of them 6 (16.21%) of COPD, 1 (7.14%) of asthma, 5 (55.55%) of ARDS, 2 (20%) of pneumonia, 2 (33.33%) of pulmonary edema, 6 (20%) of post extubation patients. Due to avoidance of intubation NIPPV does not interfere with the performance of the upper airway including eating, talking and discharge of airway secretions. Evidence collected over the past decade shows that in acute respiratory failure secondary to COPD, application of NIPPV reduces mortality and length of hospital stay. In addition, incidence of ventilator-associated pneumonia, nosocomial infections such as sepsis, sinusitis decreases due to shortening of hospital stay.14,15 Efficiency of NIPPV in the treatment of respiratory failure secondary to COPD has been shown in many published studies.16,17 In present study, the commonest indication for initiation of NIPPV was COPD (81%) followed by Bronchial asthma (80%). Other indications were Tuberculous destroyed lung (33.3%) and ARDS (27.3%). This was similar to the study by Gosavi Rakhi A et al,13 in which the commonest indication was COPD 37 (33.63%) followed by post-extubation 30 (27.27%). Similarly, in studies by Chawla, Rai and Agrawal,18-20 COPD was the commonest indication as 71.4%, 64.4% and 38.1% patients had COPD respectively. The results of this study show that invasive mechanical ventilation is more commonly used in acute respiratory failure patients including poisoning (organophosphate and related compound), ARDS and snake bite (neuroparalytic), whereas, noninvasive mechanical ventilation is commonly used in patients of acute exacerbation of chronic respiratory failure including COPD, bronchial asthma.
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