Brazilian recommendations of mechanical ventilation 2013. Part I

Hyperoxemia Induced by Oxygen Therapy in Nonsurgical Critically Ill Patients

BACKGROUND

Hyperoxemia, often overlooked in critically ill patients, is common and may have adverse consequences.

OBJECTIVE

To evaluate the incidence of hyperoxemia induced by oxygen therapy in nonsurgical critically ill patients at intensive care unit (ICU) admission and the association of hyperoxemia with hospital mortality.

METHODS

This prospective cohort study included all consecutive admissions of nonsurgical patients aged 18 years or older who received oxygen therapy on admission to the Hospital Santa Luzia Rede D'Or São Luiz adult ICU from July 2018 through June 2021. Patients were categorized into 3 groups according to Pao2 level at ICU admission: hypoxemia (Pao2<60 mm Hg), normoxemia (Pao2= 60-120 mm Hg), and hyperoxemia (Pao2 >120 mm Hg).

RESULTS

Among 3088 patients, hyperoxemia was present in 1174 (38.0%) and was independently associated with hospital mortality (odds ratio [OR], 1.32; 95% CI, 1.04-1.67; P=.02). Age (OR, 1.02; 95% CI, 1.02-1.02; P<.001) and chronic kidney disease (OR, 1.55; 95% CI, 1.02-2.36; P=.04) were associated with a higher rate of hyperoxemia. Factors associated with a lower rate of hyperoxemia were Sequential Organ Failure Assessment score (OR, 0.88; 95% CI, 0.83-0.93; P<.001); late-night admission (OR, 0.80; 95% CI, 0.67-0.96; P=.02); and renal/metabolic (OR, 0.22; 95% CI, 0.13-1.39; P<.001), neurologic (OR, 0.02; 95% CI, 0.01-0.05; P<.001), digestive (OR, 0.23; 95% CI, 0.13-0.41; P<.001), and soft tissue/skin/orthopedic (OR, 0.32; 95% CI, 0.13-0.79; P=.01) primary reasons for hospital admission.

CONCLUSION

Hyperoxemia induced by oxygen therapy was common in critically ill patients and was linked to increased risk of hospital mortality. Health care professionals should be aware of this condition because of its potential risks and unnecessary costs.

Accuracy and Sensitivity of Clinical Parameters in Predicting Successful Extubation in Patients with Acute Brain Injury

Background: Brain injuries are frequent causes of intubation and mechanical ventilation. The aim of this study was to investigate the accuracy and sensitivity of clinical parameters in predicting successful extubation in patients with acute brain injury. Methods: Six hundred and forty-four patients assisted at a high-complexity hospital were recruited. Patients were divided as for successful or failed extubation. The VISAGE score, maximum inspiratory and expiratory pressures, peak cough flow, and airway occlusion pressure at 0.1 s were used as predictors. Logistic regression analyses using ROC-curve identified values of accuracy and sensitivity. The Hosmer–Lemeshow test and the stepwise method calibrated the statistical model. Results: VISAGE score (odds ratio of 1.975), maximum inspiratory pressure (odds ratio of 1.024), and peak cough flow (odds ratio of 0.981) are factors consistent in distinguishing success from failure extubation. The ROC curve presented an accuracy of 79.7% and a sensitivity of 95.8%. Conclusions: VISAGE score, maximum inspiratory pressure and peak cough flow showed good accuracy and sensitivity in predicting successful extubation in patients with acute brain injury. The greater impact of VISAGE score indicates that patients’ neurological profile should be considered in association with ventilatory parameters in the decision of extubation.

Association of Functional Characteristics and Physiotherapy with COVID-19 Mortality in Intensive Care Unit in Inpatients with Cardiovascular Diseases

Background and Objectives: To estimate the association between admission functional outcomes and exposure to physiotherapy interventions with mortality rate in intensive care unit (ICU) inpatients with cardiovascular diseases and new coronavirus disease (COVID-19). Materials and Methods: Retrospective cohort including 100 ICU inpatients (mean (standard deviation), age 75 (16) years) split into COVID-19+ or COVID-19−. The association of in-ICU death with admission functional outcomes and physiotherapy interventions was investigated using univariable and multivariable regression models. Results: In total, 42 (42%) patients tested positive for COVID-19. In-ICU mortality rate was 37%, being higher for the COVID-19+ group (odds ratio, OR (95% CI): 3.15 (1.37−7.47), p = 0.008). In-ICU death was associated with lower admission ICU Mobility Scale score (0.81 (0.71−0.91), p = 0.001). Restricted mobility (24.90 (6.77−161.94), p < 0.001) and passive kinesiotherapy (30.67 (9.49−139.52), p < 0.001) were associated with in-ICU death, whereas active kinesiotherapy (0.13 (0.05−0.32), p < 0.001), standing (0.12 (0.05−0.30), p < 0.001), or walking (0.10 (0.03−0.27), p < 0.001) were associated with in-ICU discharge. Conclusions: In-ICU mortality was higher for inpatients with cardiovascular diseases who had COVID-19+, were exposed to invasive mechanical ventilation, or presented with low admission mobility scores. Restricted mobility or passive kinesiotherapy were associated with in-ICU death, whereas active mobilizations (kinesiotherapy, standing, or walking) were associated with in-ICU discharge in this population.

Outcomes of ventilatory asynchrony in patients with inspiratory effort

Objective

To identify the relationship of patient-ventilator asynchrony with the level of sedation and hemogasometric and clinical results.

Methods

This was a prospective study of 122 patients admitted to the intensive care unit who underwent > 24 hours of invasive mechanical ventilation with inspiratory effort. In the first 7 days of ventilation, patient-ventilator asynchrony was evaluated daily for 30 minutes. Severe patient-ventilator asynchrony was defined as an asynchrony index > 10%.

Results

A total of 339,652 respiratory cycles were evaluated in 504 observations. The mean asynchrony index was 37.8% (standard deviation 14.1 - 61.5%). The prevalence of severe patient-ventilator asynchrony was 46.6%. The most frequent patient-ventilator asynchronies were ineffective trigger (13.3%), autotrigger (15.3%), insufficient flow (13.5%), and delayed cycling (13.7%). Severe patient-ventilator asynchrony was related to the level of sedation (ineffective trigger: p = 0.020; insufficient flow: p = 0.016; premature cycling: p = 0.023) and the use of midazolam (p = 0.020). Severe patient-ventilator asynchrony was also associated with hemogasometric changes. The persistence of severe patient-ventilator asynchrony was an independent risk factor for failure of the spontaneous breathing test, ventilation time, ventilator-associated pneumonia, organ dysfunction, mortality in the intensive care unit, and length of stay in the intensive care unit.

Conclusion

Patient-ventilator asynchrony is a frequent disorder in critically ill patients with inspiratory effort. The patient’s interaction with the ventilator should be optimized to improve hemogasometric parameters and clinical results. Further studies are required to confirm these results.

Impact of a multidisciplinary checklist on the duration of invasive mechanical ventilation and length of ICU stay

Objective:

To assess the impact that implementing a checklist during daily multidisciplinary rounds has on the duration of invasive mechanical ventilation (IMV) and length of ICU stay.

Methods:

This was a non-randomized clinical trial in which the pre-intervention and post-intervention duration of IMV and length of ICU stay were evaluated in a total of 466 patients, including historical controls, treated in three ICUs of a hospital in the city of Caxias do Sul, Brazil. We evaluated 235 and 231 patients in the pre-intervention and post-intervention periods, respectively. The following variables were studied: age; gender; cause of hospitalization; diagnosis on admission; comorbidities; the Simplified Acute Physiology Score 3; the Sequential Organ Failure Assessment score; days in the ICU; days on IMV; reintubation; readmission; in-hospital mortality; and ICU mortality.

Results:

After the implementation of the checklist, the median (interquartile range) for days in the ICU and for days on IMV decreased from 8 (4-17) to 5 (3-11) and from 5 (1-12) to 2 (< 1-7), respectively, and the differences were significant (p ≤ 0.001 for both).

Conclusions:

The implementation of the checklist during daily multidisciplinary rounds was associated with a reduction in the duration of IMV and length of ICU stay among the patients in our sample.

Monitoring the electric activity of the diaphragm during noninvasive positive pressure ventilation: a case report

BACKGROUND

In patients with post-extubation respiratory distress, delayed reintubation may worsen clinical outcomes. Objective measures of extubation failure at the bedside are lacking, therefore clinical parameters are currently used to guide the need of reintubation. Electrical activity of the diaphragm (EAdi) provides clinicians with valuable, objective information about respiratory drive and could be used to monitor respiratory effort.

CASE PRESENTATION

We describe the case of a patient with Chronic Obstructive Pulmonary Disease (COPD), from whom we recorded EAdi during four different ventilatory conditions: 1) invasive mechanical ventilation, 2) spontaneous breathing trial (SBT), 3) unassisted spontaneous breathing, and 4) Noninvasive Positive Pressure Ventilation (NPPV). The patient had been intubated due to an exacerbation of COPD, and after four days of mechanical ventilation, she passed the SBT and was extubated. Clinical signs of respiratory distress were present immediately after extubation, and EAdi increased compared to values obtained during mechanical ventilation. As we started NPPV, EAdi decreased substantially, indicating muscle unloading promoted by NPPV, and we used the EAdi signal to monitor respiratory effort during NPPV. Over the next three days, she was on NPPV for most of the time, with short periods of spontaneous breathing. EAdi remained considerably lower during NPPV than during spontaneous breathing, until the third day, when the difference was no longer clinically significant. She was then weaned from NPPV and discharged from the ICU a few days later.

CONCLUSION

EAdi monitoring during NPPV provides an objective parameter of respiratory drive and respiratory muscle unloading and may be a useful tool to guide post-extubation ventilatory support. Clinical studies with continuous EAdi monitoring are necessary to clarify the meaning of its absolute values and changes over time.

Different ventilation modes combined with ambroxol in the treatment of respiratory distress syndrome in premature infants

The aim of the present study was to compare the effectiveness of different modes of mechanical ventilation in combination with secretolytic therapy with ambroxol in premature infants with respiratory distress syndrome. Seventy-three premature infants with hyaline membrane disease (HMD) (stage III–IV), also known as respiratory distress syndrome, who were supported by mechanical ventilation in the neonatal intensive care unit (NICU) of Xuzhou Central Hospital, were involved in the present study, between January 2013 and February 2015. Forty cases were randomly selected and treated with high frequency oscillatory ventilation (HFOV), forming the HFOV group, whereas 33 cases were selected and treated with conventional mechanical ventilation (CMV), forming the CMV group. Patients in the two groups were administered ambroxol intravenously at a dosage rate of 30 mg/kg body weight at the beginning of the study. The present study involved monitoring the blood gas index as well as changes in the respiratory function index in the two groups. Additionally, the incidence of complications in the premature infants in the two groups was observed prior to and following the ventilation. Pulmonary arterial oxygen tension (PaO₂), the PaO₂/fraction of inspired oxygen (FiO₂) ratio, the oxygenation index [OI = 100 × mean airway pressure (MAP) × FiO₂/PaO₂], as well as the arterial/alveolar oxygen partial pressure ratio (a/APO₂) = PaO₂/(713 × FiO₂ partial pressure of carbon dioxide (PaCO₂)/0.8) of the patients in the HFOV group after 1, 12 and 24 h of treatment were significantly improved as compared to the patients of the CMV group. However, there was no significant difference between patients in the two groups with regard to the number of mortalities, complications such as pneumothorax, bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and the time of ventilation. In conclusion, combining HFOV with ambroxol secretolytic therapy is a more viable option, as the combined treatment resulted in significant improvements in arterial blood gas levels, oxygenation and the respiratory function of lungs in preterm infants.

Pre-treatment with dexamethasone attenuates experimental ventilator-induced lung injury

OBJECTIVE

To evaluate the effects that administering dexamethasone before the induction of ventilator-induced lung injury (VILI) has on the temporal evolution of that injury.

METHODS

Wistar rats were allocated to one of three groups: pre-VILI administration of dexamethasone (dexamethasone group); pre-VILI administration of saline (control group); or ventilation only (sham group). The VILI was induced by ventilation at a high tidal volume. Animals in the dexamethasone and control groups were euthanized at 0, 4, 24, and 168 h after VILI induction. We analyzed arterial blood gases, lung edema, cell counts (total and differential) in the BAL fluid, and lung histology.

RESULTS

At 0, 4, and 24 h after VILI induction, acute lung injury (ALI) scores were higher in the control group than in the sham group (p < 0.05). Administration of dexamethasone prior to VILI induction decreased the severity of the lung injury. At 4 h and 24 h after induction, the ALI score in the dexamethasone group was not significantly different from that observed for the sham group and was lower than that observed for the control group (p < 0.05). Neutrophil counts in BAL fluid were increased in the control and dexamethasone groups, peaking at 4 h after VILI induction (p < 0.05). However, the neutrophil counts were lower in the dexamethasone group than in the control group at 4 h and 24 h after induction (p < 0.05). Pre-treatment with dexamethasone also prevented the post-induction oxygenation impairment seen in the control group.

CONCLUSIONS

Administration of dexamethasone prior to VILI induction attenuates the effects of the injury in Wistar rats. The molecular mechanisms of such injury and the possible clinical role of corticosteroids in VILI have yet to be elucidated.

OBJETIVO

Avaliar os efeitos da administração de dexametasona antes da indução de lesão pulmonar induzida por ventilação mecânica (LPIVM) na evolução temporal dessa lesão.

MÉTODOS

Ratos Wistar foram alocados em um dos três grupos: administração de dexametasona pré-LPIVM (grupo dexametasona); administração de salina pré-LPIVM (grupo controle); e somente ventilação (grupo sham). A LPIVM foi realizada por ventilação com volume corrente alto. Os animais dos grupos dexametasona e controle foram sacrificados em 0, 4, 24 e 168 h após LPIVM. Analisamos gasometria arterial, edema pulmonar, contagens de células (totais e diferenciais) no lavado broncoalveolar e histologia de tecido pulmonar.

RESULTADOS

Em 0, 4 e 24 h após LPIVM, os escores de lesão pulmonar aguda (LPA) foram maiores no grupo controle que no grupo sham (p < 0,05). A administração de dexametasona antes da LPIVM reduziu a gravidade da lesão pulmonar. Em 4 e 24 h após a indução, o escore de LPA no grupo dexametasona não foi significativamente diferente daquele observado no grupo sham e foi menor que o observado no grupo controle (p < 0,05). As contagens de neutrófilos no lavado broncoalveolar estavam aumentadas nos grupos controle e dexametasona, com pico em 4 h após LPIVM (p < 0,05). Entretanto, as contagens de neutrófilos foram menores no grupo dexametasona que no grupo controle em 4 e 24 h após LPIVM (p < 0,05). O pré-tratamento com dexametasona também impediu o comprometimento da oxigenação após a indução visto no grupo controle.

CONCLUSÕES

A administração de dexametasona antes de LPIVM atenua os efeitos da lesão em ratos Wistar. Os mecanismos moleculares dessa lesão e o possível papel clínico dos corticosteroides na LPIVM ainda precisam ser elucidados.