Non-invasive ventilation as an alternative to the endotracheal intubation is associated with less infectious complications and injury to the airways. In a study cohort that included 50 patients with type II respiratory failure with the commonest diagnosis of chronic obstructive pulmonary disease (COPD) exacerbation with or without associated co-morbidities, mechanical ventilation with non-invasive positive pressure ventilation (NIPPV) was applied and the response was observed in terms of change in various clinical and laboratory parameters after 1 hour, at the time of weaning, and 6 hours after weaning. There was significant improvement with NIPPV in form of increase in pH and PaO 2 and decrease in PaCO2 and HCO3 after 1 hour of NIPPV application, which also persisted after successful weaning. The patients who failed NIPPV had significantly high respiratory rate, low pH value, and high PaCO 2 on admission.
Keywords: Non-invasive positive pressure ventilation, type ll respiratory failure, weaning
|How to cite this article:
Vanani V, Patel M. A study of patients with type II respiratory failure put on non-invasive positive pressure ventilation. Ann Trop Med Public Health 2013;6:369-77
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Vanani V, Patel M. A study of patients with type II respiratory failure put on non-invasive positive pressure ventilation. Ann Trop Med Public Health [serial online] 2013 [cited 2021 Jan 16];6:369-77. Available from: https://www.atmph.org/text.asp?2013/6/3/369/121015
Endotracheal intubation and mechanical ventilation can be a life-saving procedure. However, the use of artificial airways may lead to infectious complications and injury to the airways. , Non-invasive ventilation is an alternative approach that was developed to avoid these complications in patients with acute respiratory failure. ,, It is often used for acute exacerbations of chronic obstructive pulmonary disease, because such exacerbations may be rapidly reversed and because the hypercapnic ventilatory failure that occurs in patients with this disorder seems to respond well to non-invasive ventilation. ,,,
The recent critical care literature has seen an explosion of articles on non-invasive respiratory support for patients presenting to hospital with respiratory failure of diverse etiology, with numerous published randomized controlled trials (RCTs) and meta-analyses on this topic. ,,,, Although this subject has been widely researched in the developed countries, there is still a paucity of literature in the developing countries, where this modality of treatment assumes greater relevance, given the limitations of resources. If such treatments could be successful in reducing the requirements of invasive mechanical ventilation (IMV) in patients with respiratory failure, it could have a potentially favorable impact on the allocation of the sparse health resources to other reversible causes of respiratory failure.
Three recent publications from India suggested that non-invasive positive pressure ventilation (NIPPV) was beneficial in cohorts of patients presenting with chronic obstructive pulmonary disease (COPD) as well as respiratory failure of varied etiology. ,,
- To evaluate clinical parameters in patients of type II respiratory failure put on NIPPV.
- To evaluate biochemical parameters like pH, PaO 2 , PaCO 2 , and bicarbonate (HCO 3 ) levels in these patients.
- To study the outcome of putting these patients with type II respiratory failure on NIPPV.
Study Design -A prospective observational study
Study Period – 2 years
Source of Data – Casualty of a tertiary referral university affiliated hospital
Sample and selection of patients
A study of patients with type II respiratory failure falling in the age group 40-90 years were included, with the below mentioned exclusion criteria.
Type II respiratory failure or acute hypercarbic respiratory failure was characterized by arterial PaCO 2 values >50 mm Hg and an arterial pH <7.30.
- Clinically perceived need for immediate life-saving endotracheal intubation or tracheostomy
- Facial deformity
- Need of airway protection because of altered conscious state or copious respiratory secretions
- Extreme claustrophobia or anxiety despite repeated attempts to facilitate the use of NIPPV
- Shock (either cardiogenic or septic) with a systolic blood pressure of <90 mm Hg despite fluid challenge or need for pressor agents
- Respiratory failure related to an acute coronary syndrome or pulmonary thromboembolism as they were managed at the intensive cardiac-care unit (ICCU).
- Kyphoscoliosis or a neuromuscular disorder as the cause of respiratory failure, e.g., myasthenia gravis, motor neuron diseases (MND), myotrophies, snake bite, organophosphate (OP) poisoning, Guillain-Barrι (GB) syndrome.
- Had clinical and radiological evidence of pneumothorax, pleural-effusion, pyothorax, hydropneumothorax, or hemothorax.
Method of study
Once eligibility was verified, informed consent was obtained from the patient’s closest relative, and patients were initiated on Bilevel Positive Airway Pressure Ventilation (BiPAP) support using the Drager Respicare CV Ventilation Therapy Unit.
IPAP was initially set at 8 cm H 2 O and increased by increments of 2 cm of H 2 O up to 18 cm H 2 O based on clinical response and arterial blood gases. The initial expiratory positive airway pressure (EPAP) was set at 4 cm H 2 O and was not altered unless clinically indicated. Humidified oxygen limited to a maximal flow rate of 5 l/min by means of nasal prongs in order to achieve a level of arterial oxygen saturation above 90% on pulse oximetry was administered. Bronchodilators and corticosteroids as nebulisers and antibiotic agents were given where clinically indicated.
Previous studies have suggested that clinical and oximetric improvements at 1 hour portend a favorable response. , On this basis, arterial blood gas analysis, at the end of 1 hour of application of NIPPV and at subsequent intervals as required, including, at the time of weaning and 6 hours after weaning were done.
Once the patient improved clinically and corroborated by improvements in arterial blood gases, weaning was initiated. During the weaning phase, the IPAP was decreased in gradations of 2-3 cm until the IPAP was 7-10 cm. The application was then switched over to intermittent use. The time of weaning, thus, was different for each patient.
NIPPV failure was defined as the need for IMV due to worsening of clinical features such as respiratory distress (tachypnea, tachycardia, increased work of breathing) hypotension, worsening of the level of consciousness, or laboratory evidence of worsening or persistent respiratory distress while on NIPPV.
If there were clinical and/or laboratory evidence of deterioration at any point during NIPPV intervention, endotracheal intubation was considered.
The primary endpoint in this study was
- The need for endotracheal intubation due to NIPPV failure or
- Successful weaning from the NIPPV or
- Patient taking discharge against medical advice
Calculations of mean and standard deviation were done wherever required. Observations were interpreted by applying unpaired and paired T test. Subsequently P values were determined and inferences were drawn.
Mechanical ventilation is a method to mechanically assist or replace spontaneous breathing.
Physiology of mechanical ventilation
Mechanical ventilators provide warmed and humidified gas to the airway in conformance with various specific volume, pressure, and time patterns. The ventilator serves as the energy source for inspiration, replacing the muscles of the diaphragm and chest wall. Expiration is passive, driven by the recoil of the lungs and chest wall; at the completion of inspiration, internal ventilator circuitry vents the airway to atmospheric pressure or a specified level of positive end expiratory pressure (PEEP). 
PEEP helps maintain patency of alveoli and small airways in the presence of destabilizing factors, improving matching of ventilation and perfusion by reversing atelectasis.
Indications of mechanical ventilation
The primary indication for initiation of mechanical ventilation is respiratory failure, of which there are two basic types, as follows  :
- Hypoxemic respiratory failure most commonly results from conditions such as pneumonia, pulmonary edema, pulmonary hemorrhage, and respiratory distress syndrome that cause ventilation-perfusion (V/Q) mismatch and shunt. Hypoxemic respiratory failure is present when arterial O 2 saturation (SaO 2 ) <90% occurs despite an inspired O 2 fraction (FIO 2 ) >0.6. The goal of ventilator treatment in this setting is to provide adequate SaO 2 through a combination of supplemental O 2 and specific patterns of ventilation that improve/match and reduce intrapulmonary shunt.
- Hypercarbic respiratory failure results from conditions that decrease minute ventilation or increase physiologic dead space such that alveolar ventilation is inadequate to meet metabolic demands. Clinical conditions associated with hypercarbic respiratory failure include neuromuscular diseases, such as myasthenia gravis, ascending polyradiculopathy, and myopathies, and diseases that cause respiratory muscle fatigue due to increased workload, such as asthma, chronic obstructive pulmonary disease, and restrictive lung disease. Acute hypercarbic respiratory failure is characterized by arterial PaCO 2 values >50 mm Hg and an arterial pH <7.30.
Types of mechanical ventilation
Traditionally divided into the following:
- Negative-pressure ventilation, where air is essentially sucked into the lungs.
- The Drinker and Shaw tank-type ventilator of 1929 was one of the first negative-pressure machines widely used for mechanical ventilation. 
- Positive pressure ventilation, where air (or another gas mix) is pushed into the trachea.
- Positive pressure ventilation can be non-invasive or invasive.
- Invasive positive pressure ventilation requires instrumentation of the airway by an endotracheal or tracheostomy tube. The positive nature of the pressure causes the gas to flow into the lungs until the ventilator breath is terminated. As the airway pressure drops to zero, elastic recoil of the chest accomplishes passive exhalation by pushing the tidal volume out. 
NIPPV is a method of providing ventilatory support using a noninvasive interface with the patient and, thus, circumvents the complications of IMV like ventilator-associated pneumonias (VAP), injury to airways, barotrauma, and post-intubation laryngeal and tracheal stenosis, while retaining the benefits of positive pressure ventilation.
Physiology of NIPPV
NIPPV can be volume- or pressure-targeted depending upon the patient’s needs. 
Non-invasive respiratory support has been provided either by –
Continuous positive airway pressure (CPAP) or BiPAP (both inspiratory and expiratory support), which are often collectively termed as NIPPV.
CPAP is PEEP applied to the airway of a patient who is breathing spontaneously. 
PEEP is an airway pressure strategy that increases the end expiratory or baseline airway pressure to a value greater than atmospheric. 
C-flex helps in reducing the pressure that the patient must overcome during exhalation and is used in delivering of CPAP in treatment of obstructive sleep apnea (OSA).
BiPAP is an airway pressure strategy that applies independent positive airway pressure to both inspiration, IPAP, and expiration, EPAP. 
IPAP provides positive pressure breaths and it improves ventilation and hypoxemia due to hypoventilation. 
EPAP is in essence CPAP and it improves oxygenation by increasing the functional residual capacity and enhancing alveolar recruitment. 
Biflex is a method of delivering BiPAP, in which the airflow during inhalation and exhalation is softened by providing pressure relief at the end of inhalation and start of exhalation, thus making breathing more natural and comfortable for the patient.
The physiological effects of CPAP include augmentation of cardiac output and oxygen delivery, improved functional residual capacity, respiratory mechanics, reduced effort in breathing,  and decreased left ventricular afterload. , The combination of IPAP with EPAP has been argued to reduce the work of breathing and to alleviate respiratory distress more effectively than CPAP alone.
Method of applying NIPPV
Essential components are as follows
- Flow generator (PAP machine) provides the airflow.
- Hose connects the flow generator (sometimes via an in-line humidifier) to the interface. It can be double-barreled or single-barreled with an expiratory valve.
- Interface (nasal or full face mask, nasal pillows, or less commonly a lip-seal mouthpiece) provides the connection to the user’s airway. The interfaces can be removed intermittently to permit patient’s meals and medications
- Flexible chin straps help in maintaining a closed pressure system, velcro-type adjustments allow quick sizing. Quick-clip instant fit belts are also available
- HEPA filters may be also be used.
- Humidification units add moisture to low humidity air.
- Some units need oxygen delivery through nasal prongs separately.
- The BiPAP may be used in one of three following modes:
- Spontaneous, spontaneous/timed, and timed.
- Mode selection depends on a patient’s ability to breath spontaneously.
- If a patient is breathing spontaneously, the IPAP and EPAP may be set at 8 cm H 2 O and 4 cm H 2 O, respectively. 
Note: Apnea ventilation is a safety feature incorporated with this mode to provide backup ventilation in the event of apnea or an extremely slow respiratory rate. It delivers a predetermined tidal volume, respiratory rate, and FiO 2 to the patient. 
The spontaneous/timed mode is used as a backup mechanism and the breaths per minute (BPM) is set 2-5 breaths below the patient’s spontaneous rate.
In the timed mode, IPAP and EPAP is set as above and the BPM at slightly higher than the patient’s spontaneous rate.
Adjustments during maintenance phase
IPAP levels are generally determined by monitoring patient’s clinical and physiological response to gradual changes of IPAP rather than by directly measuring the volume delivered. 
IPAP may be increased in increments of 2 cm H 2 O to enhance the pressure boost to improve alveolar ventilation, normalize PaCO 2 , and reduce the work of breathing.
A larger delivered volume may be obtained by –
- Increasing the IPAP level, decreasing the EPAP level, increasing the compliance of the lung/thorax system, and reducing the airflow resistance.
- EPAP should be increased by 2 cm H2O to increase functional residual capacity and oxygenation in patients with intra pulmonary shunting.
- It is not possible to increase the EPAP higher than IPAP.
- When the EPAP is the same as IPAP, CPAP results.
- Use supplemental oxygen if baseline saturation remains low despite appropriate IPAP and EPAP settings.
Weaning can be initiated when the underlying medical illness has been treated and the patient has stable clinical and physiological signs/parameters as on arterial blood gas analysis on a minimum setting of IPAP = 12 cm H 2 O, EPAP = 4 cm H 2 O for 4-6 hours. These can vary from individual to individual and are decided on a case-to-case basis.
Then, controlled oxygen via face mask is delivered to maintain SpO 2 >92% .
Care and maintenance
Proper maintenance is essential for proper functioning, long unit life, and patient comfort. Units must be checked regularly for wear and tear and kept clean. Hoses, masks, and humidification units accumulate exfoliated skin, particulate matter, and can even develop mold and algae that needs to be cleaned regularly.
Types of interfaces
- Nasal masks: A mask that covers only the nose. A minor leak is acceptable, a facial mask is considered when the leak is significant. 
- Nasal pillows: Two small cushions that fit under the nose used during CPAP therapy.
- Full face masks (oronasal): Regurgitation, aspiration, and asphyxiation during ventilator failure can be potential problems. 
- Oral mouthpieces with and without lipseals.
Problems with interfaces
The various problems that can be encountered with the use of various interfaces includes the following  :
- Air leaks that can be minimized with the use of appropriately sized mask, adjusting head gear, and using foam pads and chin straps.
- Nasal congestion/discharge can be managed by adding filter and/or humidity.
- Nasal airway drying is overcome by increasing fluid intake, room humidity, and nasal saline or water-based lubricant.
- Pressure points, sore or dry eyes, skin breakdown/irritation that can be overcome by added skin care like application of oil and use of cushion pads and/or proper-sized masks.
- Claustrophobia and patient non-compliance, which can be managed with frequent reassurance to the patient.
- Regurgitation, aspiration, and asphyxiation during ventilator failure.
Primary indications of NIPPV includes
- OSA: Sleep apnea is defined as a temporary pause in breathing that lasts at least 10 sec during sleep. It can be caused by airflow obstruction (OSA), loss of neurologic breathing effort (central sleep apnea; CSA), or a combination of both (mixed sleep apnea; MSA); C-flex method is used for the treatment of OSA. 
- Reduction of respiratory workload in obesity.
- Acute hypercapnic exacerbations of COPD in preventing intubation of end-stage COPD patients.
- Acute cardiogenic pulmonary oedema.
Contraindications for use of NIPPV includes the following:
- Apnoea due to neuromuscular causes and progressive hypoventilation. 
- Inability to handle secretions by the patient.
- Hypotension and fatigue of respiratory muscles.
- Claustrophobia and facial trauma.
Observations and discussions
In the present study, 50 patients were enrolled. The study observations are as follows:
The mean (SD) age of study cohort was 62.36 (12.34) years with an age range of 40-90 years. Similarly, in the studies by George et al.  and Lt. Col. SP et al.,  the average age of patients enrolled was >50 years.
The present study cohort has a male preponderance (43/50) of 86%; the study of Lt. Col. et al.  had a male preponderance of 64%. However, in a similar study by George et al.,  females constituted 56% of the total cohort.
The most common symptom on presentation was breathlessness seen in all the enrolled patients. Cough was present in a sizeable number of patients, i.e., 44%. A relatively small number of patients, 10% and 6% respectively, also had fever and chest pain on presentation, which was clinically diagnosed as pneumonia.
Most common clinical diagnosis included COPD exacerbation on the basis of the clinical history and physical examination, 84% (42/50) with or without associated co-morbidities [Table 1].
||Table 1: Clinical diagnosis on presentation
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Level of consciousness was evaluated as oriented, disoriented, and drowsy; 48% of the patients were disoriented on admission, whereas only 18% (9/50) were drowsy. Eight patients of these failed the trial of NIPPV. The rest 34% were oriented at the time of admission.
Oedema as bilateral pedal oedema with a raised JVP was noted in 12% of patients who were put as clinical diagnosis of congestive cardiac failure.
The mean pulse rate on admission was 97.24 per min, with a range of 88-136 per min.
The mean systolic blood pressure on admission was 138.96 mm Hg with a range of 128-168 mm Hg, and the mean diastolic blood pressure was 96.72 with a range of 86-114 mm Hg.
Respiratory rate had a mean value of 24.32 breaths per min with a range of 20-32 breaths per min.
Mean age of the patients who failed NIPPV was significantly higher (P < 0.001) than those who succeeded NIPPV in the present study [Table 2].
||Table 2: Comparison age within the present study
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Respiratory rate at admission was significantly higher in the patients who failed NIPPV (P < 0.001). Admission respiratory rate in a similar study by George et al.  compared in [Table 1] below showed similar significant (P < 0.01) results [Table 3].
||Table 3: Comparison of mean respiratory rate (breaths/ min.)
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Mean duration of NIPPV in the responders group was 38.45 (SD = 17.76) hours. Those who failed NIPPV had to be intubated, and they tolerated the intervention for a mean of only 1.25 hours.
Thus, on admission, respiratory rate can be used potentially in the future, as a predictor of outcome of successful NIPPV intervention. 
No other significant differences were observed in the baseline characteristics of patients who failed NIPPV versus those who succeeded.
Of the 8 patients who failed NIPPV, 5 were intubated and mechanically ventilated (all of these had clinical and, later confirmed, radiological evidence of pneumonitis), 1 of them was subsequently successfully extubated; 4 patients of these eventually expired due to septicaemic shock due to various reasons and 3 patients took discharge against medical advice not willing for further intervention of intubation and invasive ventilation.
pH value on admission was significantly lower in patients who failed NIPPV (P < 0.001). PaCO 2 value at admission was significantly higher in patients who failed NIPPV (P < 0.001).
HCO 3 levels on admission were significantly higher in patients who failed NIPPV (P < 0.001). However, this subset of patients also had higher levels of PaCO 2 , of which, it has a direct relation and also depends on the subject’s ability to compensate. These observations, however, do not co-relate with a similar comparison done by George et al [Table 4]. 
||Table 4: Comparison of mean values of pH and paco2 in nippv successful and failed patients
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These improvements also continued up to weaning and were maintained post-weaning from noninvasive ventilation as depicted in the [Figure 1] and [Table 5].
||Table 5: Mean (SD) of pH at various observed intervals in patients treated successfully with NIPPV
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||Figure 1: Mean values for the pH at various observed times in patients successfully treated with NIPPV
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Similar observations of improvements in the pH values at various observed intervals of time were made by George et al.  and Lt. Col. SP et al.  with variable degrees of significance as P < 0.001 in the former and P < 0.05 in the latter [Table 6].
||Table 6: Comparison of mean ph values at various observed intervals in successfully treated patients
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Thus, improvements in the serial pH values may be used potentially in the future as a predictor of outcome of successful NIPPV intervention.
NIPPV was also associated with significant improvements in PaCO 2 after 1 hour of intervention in the successfully treated group [Figure 2].
||Figure 2: Changes in PaCO2 1 hour after initiation of NIPPV in successfully treated patients. (N=42)
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These improvements also continued up to weaning and were maintained post-weaning from noninvasive ventilation [Table 7].
||Table 7: Mean (SD) of PaCO2 at various observed intervals in patients treated successfully with NIPPV
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Similar observations of improvements in the PaCO 2 values at various observed intervals of time were made by George et al.  and Lt. Col. SP et al.  with variable degrees of significance as P < 0.001 in the former and P < 0.05 in the latter [Table 8].
||Table 8: Comparison of mean PaCO2 values at various observed intervals in successfuly treated patients
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Values in parenthesis indicates P value compared with admission values and hence significance.
As depicted above, NIPPV was also associated with significant improvements (P < 0.001) in the mean PaO 2 and HCO 3 levels after 1 hour. This improvement continued up to the time of weaning. The improvement continued even post-weaning determined after 6 hours for HCO 3 levels. A small insignificant fall was seen post-weaning for PaO 2 from levels of 103.5 to 94.71 [Table 9].
||Table 9: mean (SD) of PaO2 and HCO3 levels at various observed intervals in patients treated successfully
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The success rate with NIPPV was 84% with 42 patients weaned successfully off NIPPV in this study. These results are consistent with previously published studies reporting success rates of 50-80% with NIPPV [Table 10]. ,,,
||Table 10: comparison of successful outcome of NIPPV intervention
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The use of NIPPV in the management of acute exacerbations of COPD as well as ARF of other etiology is now supported by RCTs and meta-analyses. ,,,
NIPPV was well-tolerated in our patients. The most common problem faced with NIPPV was air leaks seen in a 30% of the patients (15/50). This was due to ill-fitting masks and with the use of appropriately sized mask, it was minimized.
Mild skin bruising occurred in 12 patients (24%), while skin necrosis and pressure sores developed in only 2 patients. This was managed with frequent reassurance to the patient, added skin care like application of oil, cushion pads, and use of a mask of appropriate size, and by avoiding placing the head straps too tightly.
Limitations of our study
- The lack of a control arm without the intervention (NIPPV) limits the impact of the study. Although a concurrent case control study would have given more credence to the study, we felt that withholding NIPPV would be inappropriate, given the evidence of benefit in other studies.
- A retrospective case control study was again not considered given the potential for bias in selection of controls.
- It was impossible to draw meaningful conclusions on the impact of NIPPV in the type I respiratory failure in our study as it was not addressed to systematic review; however, it suggested that the benefit of NIPPV extended to the hypoxemic respiratory failure patient, albeit with only modest benefits in clinical endpoints. , NIPPV has however been demonstrated in RCTs and meta-analyses to be beneficial in patients presenting with cardiogenic pulmonary edema. 
- The following conclusions were derived at the end of the study of 50 patients with type II respiratory failure put on NIPPV:
- The study cohort had a male preponderance (43/50) with a mean (SD) age of 62.36 (12.34) years. Mean age of the patients who failed NIPPV was significantly higher than those who succeeded.
- The most common symptom on presentation was breathlessness seen in all the patients.
- In our study cohort, the most common clinical diagnosis included COPD exacerbation, 95% (47/50) with or without associated co-morbidities.
- Patients with a poor level of consciousness were associated with a poor response to NIPPV, ultimately requiring intubation.
- Respiratory rate at admission was significantly (P < 0.001) higher in NIPPV non-responders as compared with NIPPV responders, and this could possibly be used to predict response to NIPPV.
- Mean pH value on admission was significantly lower (p<0.001) in patients who failed NIPPV i.e. 7.09 compared to that in NIPPV successful group 7.213. (Patients with pH<7.3 were enrolled in our study) Thus patients with pH between 7.2-7.3 fared well on NIPPV and were successfully weaned. This could perhaps set a lower limit of pH as an indication for NIPPV.
- NIPPV was associated with significant improvements (P < 0.001) in pH from 7.213 to 7.324 after 1 hour of application. This improvement continued up to the time of weaning and was maintained post-weaning.
- Mean PaCO2 value at admission was significantly higher (P < 0.001) in patients who failed NIPPV (99.5) compared with NIPPV responders (69.10) and, thus, could also possibly be used to predict response to NIPPV.
- There was a significant improvement (P < 0.001) in the mean PaCO2 levels within an hour of application of NIPPV from 69.10 to 55.36 mm Hg. This improvement continued up to weaning and was maintained post-weaning from IPPV.
- NIPPV was associated with significant improvements (P < 0.001) in HCO3 levels at 1 hour of application. This improvement continued up to the time of weaning and was maintained post-weaning corroborating with improvements in PaCO2.
- There was a significant improvement (P < 0.001) in the mean PaO2 levels within an hour of application of NIPPV from 75.12 to 100.57 mm Hg. This improvement continued up to weaning. A small insignificant fall was seen 6 hours post-weaning.
- The study, thus, demonstrated that NIPPV is not only a feasible ventilatory modality but also a treatment that is associated with significant improvements in clinical and biochemical outcomes.
- NIPPV with BiPAP was successful in 84% of patients in our study cohort with 42 patients weaned successfully off NIPPV. NIPPV, thus, circumvents the complications of IMV like VAP,  injury to airways, barotrauma, and post-intubation laryngeal and tracheal stenosis while retaining the benefits of positive pressure ventilation.
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Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10]