Severe viral pneumonia in young adults

Non-invasive ventilation for preoxygenation before general anesthesia: a systematic review and meta-analysis of randomized controlled trials

Background and objectives

Preoxygenation is crucial for providing sufficient oxygen reservoir to a patient before intubation and enables the extension of the period between breathing termination and critical desaturation (safe apnoea time). Conventionally, face mask ventilation is used for preoxygenation. Non-invasive ventilation is a new preoxygenation method. The study objective was to compare the outcomes of non-invasive ventilation and face mask ventilation for preoxygenation.

Method

PubMed, Embase, Cochrane Library, and the ClinicalTrials.gov registry were searched for eligible studies published from database inception to September 2021. Individual effect sizes were standardized, and a meta-analysis was conducted using random effects models to calculate the pooled effect size. Inclusion criteria were randomised controlled trials of comparing the outcomes of non-invasive ventilation or face mask ventilation for preoxygenation in patients scheduled for surgeries. The primary outcome was safe apnea time, and the secondary outcomes were post-operative complications, number of patients who achieved the expired O₂ fraction (FeO₂) after 3 min of preoxygenation, minimal SpO₂ during tracheal intubation, partial pressure of oxygen in the arterial blood (PaO₂) and partial pressure of carbon dioxide (PaCO₂) after preoxygenation, and PaO₂ and PaCO₂ after tracheal intubation.

Results

13 trials were eligible for inclusion in this study. Significant differences were observed in safe apnoea time, number of patients who achieved FeO₂ 90% after preoxygenation for 3 min, and PaO₂ and PaCO₂ after preoxygenation and tracheal intubation. Only in the non-obese subgroup, no significant difference was observed in safe apnoea time (mean difference: 125.38, 95% confidence interval: − 12.26 to 263.03).

Conclusion

Non-invasive ventilation appeared to be more effective than conventional methods for preoxygenation. We recommend non-invasive ventilation based on our results.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01842-y.

Critically Ill Adults With Coronavirus Disease 2019 in New Orleans and Care With an Evidence-Based Protocol

Background

Characteristics of critically ill adults with coronavirus disease 2019 (COVID-19) in an academic safety net hospital and the effect of evidence-based practices in these patients are unknown.

Research Question

What are the outcomes of critically ill adults with COVID-19 admitted to a network of hospitals in New Orleans, Louisiana, and what is an evidence-based protocol for care associated with improved outcomes?

Study Design and Methods

In this multi-center, retrospective, observational cohort study of ICUs in four hospitals in New Orleans, Louisiana, we collected data on adults admitted to an ICU and tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between March 9, 2020 and April 14, 2020. The exposure of interest was admission to an ICU that implemented an evidence-based protocol for COVID-19 care. The primary outcome was ventilator-free days.

Results

The initial 147 patients admitted to any ICU and tested positive for SARS-CoV-2 constituted the cohort for this study. In the entire network, exposure to an evidence-based protocol was associated with more ventilator-free days (25 days; 0-28) compared with non-protocolized ICUs (0 days; 0-23, P = .005), including in adjusted analyses (P = .02). Twenty patients (37%) admitted to protocolized ICUs died compared with 51 (56%; P = .02) in non-protocolized ICUs. Among 82 patients admitted to the academic safety net hospital’s ICUs, the median number of ventilator-free days was 22 (interquartile range, 0-27) and mortality rate was 39%.

Interpretation

Care of critically ill COVID-19 patients with an evidence-based protocol is associated with increased time alive and free of invasive mechanical ventilation. In-hospital survival occurred in most critically ill adults with COVID-19 admitted to an academic safety net hospital’s ICUs despite a high rate of comorbidities.

The use of non-invasive ventilation during acute respiratory failure due to pneumonia

The use of non-invasive ventilation in patients with community-acquired pneumonia is controversial since this is associated with high rates of treatment failure, compared with other causes of severe acute respiratory failure. The populations of patients with community-acquired pneumonia who have demonstrated better response to non-invasive ventilation are those with previous cardiac or respiratory disease, particularly chronic obstructive pulmonary disease. By contrast, the use of non-invasive ventilation in patients with community-acquired pneumonia without these pre-existing diseases should be very cautious and under strict monitoring conditions, since there are increasing evidences that the unnecessary delay in intubation of those patients who fail treatment with non-invasive ventilation is associated with lower survival. Pulmonary complications of immunosuppressed patients are associated with high rates of intubation and mortality. The use of non-invasive ventilation in these patients may decrease the need for intubation and improve the poor outcome associated with these complications. Continuous positive airway pressure has been used to treat acute respiratory failure in several conditions characterised by alveolar collapse. While this is extremely useful in patients with acute cardiogenic pulmonary oedema, the efficacy in pneumonia seems limited to immunosuppressed patients with pulmonary complications. Conversely, there are no sufficient evidences on the efficacy of continuous positive airway pressure in immunocompetent patients with pneumonia and severe acute respiratory failure.

Community-acquired adenovirus pneumonia in a patient with chronic lymphatic leukaemia

Described here is a severe case of community-acquired adenovirus pneumonia that occurred in a previously healthy 54-year-old male who was later determined to have stage A chronic lymphatic leukemia. The clinical presentation was consistent with that of atypical pneumonia. Testing with PCR revealed adenovirus in a bronchoalveolar lavage sample, while all other tests to determine a bacterial or virological etiology were negative. Further examination of the patient revealed the previously undiagnosed chronic lymphatic leukemia. Following treatment with human immunoglobulin and oxygen therapy with continuous positive airway pressure support the patient recovered from the pneumonia completely.

Medical treatment of viral pneumonia including SARS in immunocompetent adult

Since no randomized controlled trials have been conducted on the treatment of viral pneumonia by antivirals or immunomodulators in immunocompetent adults, a review of such anecdotal experience are needed for the more rational use of such agents. Case reports (single or case series) with details on their treatment and outcome in the English literature can be reviewed for pneumonia caused by human or avian influenza A virus (50 patients), varicella zoster virus (120), adenovirus (29), hantavirus (100) and SARS coronavirus (SARS-CoV) (841). Even with steroid therapy alone, the mortality rate appeared to be lower when compared with conservative treatment for pneumonia caused by human influenza virus (12.5% vs. 42.1%) and hantavirus (13.3% vs. 63.4%). Combination of an effective antiviral, acyclovir, with steroid in the treatment of varicella zoster virus may be associated with a lower mortality than acyclovir alone (0% vs. 10.3%). Combination of interferon alfacon-1 plus steroid, or lopinavir/ritonavir, ribavirin plus steroid were associated with a better outcome than ribavirin plus steroid (0% vs. 2.3% vs. 7.7%, respectively). Combination of lopinavir/ritonavir plus ribavirin significantly reduced the virus load of SARS-CoV in nasopharyngeal, serum, stool and urine specimens taken between day 10 and 15 after symptom onset when compared with the historical control group treated with ribavirin. It appears that the combination of an effective antiviral and steroid was associated with a better outcome. Randomized therapeutic trial should be conducted to ascertain the relative usefulness of antiviral alone or in combination with steroid.

Noninvasive positive-pressure ventilation in patients with acute respiratory failure

This article provides a systematic review of the literature on the application of noninvasive ventilation in various forms of hypercapnic and hypoxemic respiratory failures. A description of the underlying pathophysiology is followed by a review of physiologic data explaining the mechanisms of action of noninvasive ventilation. A critical review of clinical studies is presented with specific suggestions. The methodology of correctly implementing and monitoring noninvasive ventilation in patients with acute respiratory failure, critical to success, is detailed.

Shortcomings of using two jet nebulizers in tandem with an aerosol face mask for optimal oxygen therapy

Herein, a laboratory model which allows measurement of simulated distal airway oxygen percentage at different breathing patterns is described to illustrate the shortcomings of conventional O2 devices and, in particular, the aerosol face mask with two jet nebulizers (AFM-DF) in tandem. A table showing the degree of dilution which occurred during simulation of various breathing patterns while using the AFM-DF is also presented. Data revealed that when 60 percent was desired, 13 of 27 measurements were less than 55 percent. The worst-case scenario for 60 percent desired was 48 percent measured. When 80 percent was desired, less than 70 percent was delivered in 24 of the 27 breathing patterns simulated. Less than 60 percent was measured on 12 occasions, with 51 percent being the lowest measurement. When 100 percent O2 was desired, less than 80 percent was measured in 25 of 27 breathing patterns. Less than 60 percent was measured in ten of those. Fifty percent was the lowest analyzed value for the 100 percent setting. The inadequacy of AFM-DF is described in three case studies. A high-flow nonrebreathing face mask (HFM) to address the subset of patients is also discussed. A peak inspiratory flow prediction chart is also documented and may be useful in setting optimal flows when using high-flow systems. The patients in whom intubation and mechanical ventilation (or use of continuous mask CPAP) are indicated can be more clearly identified with a trial of high-flow O2 therapy (with a system that assures adequate flow to meet the patient's peak inspiratory flow demands). In the remainder of patients, those higher-risk modalities will be precluded.

A new continuous positive airway pressure (CPAP) device

While continuous positive airway pressure (CPAP) is being increasingly employed for many forms of acute respiratory failure and postoperative hypoxaemia, most CPAP systems are either 'home made' or incorporated in sophisticated ventilators used in intensive care units. This paper describes the development of a continuous low flow CPAP system using a large latex reservoir bag and venturi generated positive end expiratory pressure (PEEP). The system has been successfully used for over twelve months in the general wards, the intensive care unit, accident and emergency department, the recovery ward and the coronary care unit.

PEEP and CPAP

Positive end-expiratory pressure (PEEP) maintains airway pressure above atmospheric at the end of expiration, and may be used with mechanical ventilation or spontaneous breathing. CPAP, or continuous positive airway pressure, refers to spontaneous ventilation with a positive airway pressure being maintained throughout the whole respiratory cycle. PEEP/CPAP primarily improves oxygenation by increasing functional residual capacity, and may increase lung compliance and decrease the work of breathing. PEEP/CPAP may be applied using endotracheal tubes, nasal masks or prongs, or face masks or chambers to treat a wide range of adult and paediatric respiratory disorders. Complications associated with their use relate to the pressures applied and include pulmonary barotrauma, decreased cardiac output and raised intracranial pressure.

The importance of the balloon reservoir volume of a CPAP system in reducing the work of breathing

We have previously reported, that the work of breathing in spontaneously breathing patients on CPAP could be significantly reduced by increasing the volume of the balloon reservoir in the circuit of a CPAP system from 3 to 23 l. We now report a study designed to determine the optimum balloon reservoir volume for the minimization of the work of breathing. Twenty intubated, spontaneously breathing patients were connected to a CPAP system with interchangeable balloon reservoirs. In each patient the work of breathing was measured for reservoir volumes of 3, 6, 12, 18, and 24 l attached in random order, while the positive airway pressure was held constant at 10 cm H2O. The balloons were constructed of the same material and had similar compliance. Rebreathing was prevented with use of one-way valves. Significant (p less than 0.001) decreases in the work of breathing were found on increasing reservoir volumes from 3 to 6, 6 to 12, and 12 to 18 l. A less significant (p less than 0.01) decrease in the work of breathing was found between reservoirs of 18 and 24 l. Rebreathing did not occur with significantly (p less than 0.001) lower flow rates when large reservoirs were used. We conclude that a balloon reservoir of 18 l represents the best compromise between reduction in the work of breathing, utilization of low source flow, and convenience of clinical use.

The importance of the circuit capacity in the administration of CPAP

The effectiveness of Continuous positive airway pressure (CPAP) administration in improving blood oxygenation and the importance of the circuit capacity, by checking two different volumes of balloon reservoirs (a 3 l versus 23 l balloon), in reducing the work of breathing is presented. Twenty-five postoperative patients, after major gastrointestinal interventions were included in this study. Each patient being studied under three different conditions: Phase I: spontaneous breathing, Phase II: CPAP - 11 cmH2O, 3 l balloon reservoir; Phase III: CPAP - 11 cmH2O, 23 l balloon reservoir. All patients were intubated and were breathing room air. The results obtained clearly show a significant improvement in blood oxygenation due to CPAP, p less than 0.001. In addition, the work of breathing was considerably reduced utilizing a large capacity system with significant lower flow rates, p less than 0.001 and p less than 0.0001 respectively. Furthermore, rebreathing was prevented by maintaining continuous bubbling in the exit chamber and proved by having no change in PaCO2.

Overwhelming pneumonia

A classification of normal-abnormal hosts and pathogens forms the basis for discussion of the diagnosis and management of pneumonia in the critical care setting. In order to arrive at the appropriate therapy for the unusual as well as the usual causative organisms of pneumonia, individual assessment of the need for invasive procedures must be made. The critical feature, however, is to consider the wide spectrum of possibilities for each individual patient.

Efficacy of continuous positive airway pressure administered by face mask

The efficacy of administering continuous positive airway pressure (CPAP) by face mask was evaluated in 40 consecutive patients treated with 10 cm of water pressure or greater. Thirty-five patients were treated for progressive hypoxemia with all patients improving their PaO2/FIO2 ratio within the first hour of therapy. Oxygen delivery, when measured, also improved in each patient, although five patients ultimately required endotracheal intubation and higher CPAP levels to further improve their arterial hypoxemia. Five other patients were treated for atelectasis unresponsive to the usual therapeutic measures, with three patients demonstrating roentgenographic improvement. Face mask CPAP proved to be a safe and effective method for treating hypoxemia associated with early progressive respiratory distress in alert, spontaneously breathing patients.

Treatment of acute pulmonary failure by CPAP via face mask: when can intubation be avoided?

Continuous positive airway pressure (CPAP) is used frequently to improve gas exchange in acute pulmonary failure. We investigated clinical and respiratory variables in 98 patients presenting with two or more of the classical criteria for endotracheal intubation and mechanical ventilation. CPAP applied by a face mask was efficient in 60 cases. Posttraumatic and postoperative pulmonary problems responded better to this therapy than lung dysfunction secondary to left heart failure, sepsis or pneumonia. Abundant expectorations, discoordination of respiratory movements and an increase in arterial carbon dioxide were frequently associated with failure of CPAP by mask and the necessity of endotracheal intubation and mechanical ventilation.

Diffuse pneumonitis due to adenovirus type 21 in a civilian

A patient with severe pneumonitis due to adenovirus type 21 responded to oxygen delivered by continuous positive airway pressure through a face mask. Pulmonary function studies over ten months demonstrated resolving, restrictive lung disease. The prognosis of severe adenovirus pneumonia may be better than expected based on previous reports.

Treatment of the adult respiratory distress syndrome with continuous positive airway pressure

Fifteen patients in the early stages of the adult respiratory distress syndrome with severe hypoxemia who were capable of maintaining adequate spontaneous ventilation were treated with continuous positive airway pressure (CPAP). The optimal level of CPAP was adjusted for each patient to achieve the highest oxygenation with the least adverse hemodynamic effects. The optimal intravascular volume, judged by pulmonary arterial occlusion pressure, was maintained by infusion of lactated Ringer's solution. Application of an optimal CPAP ranging between 10 and 25 cm H2O significantly reduced the intrapulmonary shunt, increased the forced vital capacity, and decreased the respiration rate. The improvement in pulmonary status was achieved with no significant changes in cardiac output or the arterial-mixed venous oxygen content difference. Early application of an adjusted level of positive end-expiratory pressure using CPAP in patients with adequate levels of fluid is an effective and safe method of treating selected groups of patients in the early stages of the adult respiratory distress syndrome.

Severe hypoxemia secondary to pulmonary embolization treated successfully with the use of a CPAP (continuous positive airway pressure) mask

We describe a patient who was admitted with acute onset of dyspnea and pleuritic chest pain. The patient was in acute hypoxic respiratory failure documented by arterial blood gas levels. The severe hypoxemia was refractory to 100 percent O2 administration. The cause of the patient's sudden deterioration was a pulmonary embolus documented by angiography. The patient was managed successfully with heparin therapy. A continuous positive airway pressure (CPAP) mask corrected the severe hypoxemia, which otherwise would have required a more invasive method of respiratory support.

Acute miliary tuberculosis presenting as acute respiratory failure

A 42 year old pregnant woman was admitted in acute respiratory failure. Viral pneumonia was suspected and oxygen therapy, CPAP, water restriction and diuretics were started with good response. She remained febrile and had an abnormal chest X-ray, a diagnosis of miliary tuberculosis was confirmed by transbronchial fibreoptic lung biopsy.

Continuous positive pressure ventilation in children with bronchopneumonia

The application of a small end-expiratory pressure of 5 cmH2O to the assisted ventilation of nineteen children (mean age 19 months) with bronchopneumonia was compared with intermittent positive pressure ventilation. Within 1 h of introducing continuous positive pressure ventilation the alveolar-to-arterial oxygen gradient was reduced in most patients, with an increase in functional residual capacity and a decrease in total pulmonary blood shunt. Physiological dead space was also reduced, a feature not observed in other studies, and the significance of this finding is discussed. The use of continuous positive pressure ventilation in broncho-pulmonary infection was shown to be effective even at small pressures, and can be recommended especially for patients requiring long-term ventilation.