Predictors of Negative Pressure Ventilation Response in Pediatric Acute Respiratory Failure.

BACKGROUND: Use of negative pressure ventilation is neither well described nor widespread in pediatric critical care; existing data are from small, specialized populations. We sought to describe a general population of critically ill subjects with acute respiratory failure supported with negative pressure ventilation to find predictors of response or failure. METHODS: We conducted a retrospective cohort study of subjects 0-18 y old admitted to a single (non-cardiac) pediatric ICU who received acute respiratory failure support via negative pressure ventilation from May 2015 through May 2016. RESULTS: In 118 subjects, the most common causes of acute respiratory failure were viral bronchiolitis (86.4%) and pneumonia (15.3%). A majority of subjects (68.6%) stabilized with negative pressure ventilation and did not need a change of respiratory support; in those who failed with negative pressure ventilation, median time to respiratory support change was 5.1 h (interquartile range 1.9-11.0). Subjects stabilized with negative pressure ventilation did not differ from those needing a change of respiratory support in terms of age, comorbidities, or FIO2 at initiation of ventilation. Compared to those who did not respond to negative pressure ventilation, mean SpO2 /FIO2 was higher at 1 h after start of negative pressure ventilation (218.8 vs 131.7) in those who did respond. Subjects with SpO2 /FIO2 < 192 after 1 h on negative pressure ventilation support had 5-fold higher odds of needing a respiratory support change (odds ratio 5.143, 95% CI 1.17-22.7, P = .031). Analysis of SpO2 /FIO2 was limited by 81.3% (96/118) of subjects who had an SpO2 > 97% at 1 h after the start of negative pressure ventilation. CONCLUSIONS: Negative pressure ventilation successfully supported 69% of pediatric subjects with all-cause acute respiratory failure. Oxygen requirement was lower in subjects who were responsive to negative pressure ventilation within 1 h of initiation. Standardized negative pressure ventilation protocols should include weaning of supplemental oxygen to determine responsiveness.

A novel intermittent negative air pressure device ameliorates obstructive sleep apnea syndrome in adults.

PURPOSE: Patients with obstructive sleep apnea syndrome (OSAS) have difficulties in compliance with continuous positive airway pressure (CPAP) and the treatment outcome is heterogeneous. We proposed a proof-of-concept study of a novel intermittent negative air pressure (iNAP®) device for physicians to apply on patients who have failed or refused to use CPAP. METHODS: The iNAP® device retains the tongue and the soft palate in a forward position to decrease airway obstruction. A full nightly usage with the device was evaluated with polysomnography. Subgrouping by baseline apnea-hypopnea index (AHI) and body mass index (BMI) with different treatment response criteria was applied to characterize the responder group of this novel device. RESULTS: Thirty-five patients were enrolled: age 41.9 ± 12.2 years (mean ± standard deviation), BMI 26.6 ± 4.3 kg/m2, AHI 41.4 ± 24.3 events/h, and oxygen desaturation index (ODI) 40.9 ± 24.4 events/h at baseline. AHI and ODI were significantly decreased (p < 0.001) by the device. Patients with moderate OSAS, with baseline AHI between 15 to 30 events/h, achieved 64% response rate; and non-obese patients, with BMI below 25 kg/m2, achieved 57% response rate, with response rate defined as 50% reduction in AHI from baseline and treated AHI lower than 20. There were minimal side effects reported. CONCLUSIONS: In a proof-of-concept study, the device attained response to treatment as defined, in more than half of the moderate and non-obese OSAS patients, with minimal side effects.

Edema pulmonar por presión negativa / Negative pressure pulmonary edema

El edema pulmonar por presión negativa representa el 0.1% de las complicaciones pulmonares de los pacientes post ­ quirúrgicos, y la condicionante del incremento de dicha incidencia es la existencia de algún tipo de obstrucción de la vía aérea llegando hasta un 11% de casos. Su incidencia y prevalencia no son claras ya que es una entidad con infradiagnóstico. En los reportes de casos se coincide que la mayoría de pacientes son jóvenes con evaluaciones de riesgo quirúrgico bajos previamente sanos y que desarrollan en forma súbita un cuadro de edema agudo de pulmón, casi siempre posterior a la anesthesia, encontrándose ya no orointubados...(AU)

Use of negative extrathoracic pressure to improve hemodynamics after cardiac surgery.

BACKGROUND: Little attention is given to the mode of mechanical ventilation after cardiac surgery. Positive pressure ventilation with positive end-expiratory pressure (PEEP) has been shown to reduce cardiac output. We hypothesized that positive pressure ventilation with continual negative pressure applied to the chest through a cuirass would increase cardiac output in coronary artery bypass graft patients immediately after surgery. METHODS: Twenty patients with a normal left ventricular ejection fraction were studied 2 hours after coronary artery bypass graft surgery. The patients were ventilated with synchronized intermittent mandatory ventilation (SIMV) and PEEP. Hemodynamic variables and blood gases were studied using four modes of ventilation after 15 minutes in each mode: A (baseline 1) = SIMV and 5 cmH(2)O of PEEP; B = SIMV without PEEP; C = SIMV without PEEP and with continuous negative pressure applied to the thorax at -20 cmH(2)O; D (baseline 2) = SIMV and 5 cmH(2)O of PEEP. The results of the two baselines were averaged. RESULTS: All patients were hemodynamically stable during the trial. Heart rate, blood pressure, and gas exchange were not affected by the changes in ventilatory modes. With continual negative pressure, the stroke volume index and cardiac index were significantly increased relative to ventilation with SIMV and PEEP by 3.21 mL x min(-1) x m(-2) (9.0%) and 0.45 L x min(-1) x m(-2) (13.8%), respectively. Continual negative pressure also reduced venous and wedge pressure. CONCLUSIONS: Continual negative pressure attenuates the negative effects of positive pressure ventilation on cardiac output. Although the improvement in this cohort with normal ventricular function is modest, this pilot study demonstrates that the mode of ventilation may have potentially important effects on cardiac output.

Breathing pattern and arterial blood gases during Nd-YAG laser photoresection of endobronchial lesions under general anesthesia: use of negative pressure ventilation: a preliminary study.

STUDY OBJECTIVE: To evaluate the efficacy of negative pressure ventilation (NPV) in avoiding or reducing apneas and related hypoxemia and respiratory acidosis during laser therapy (LT) of endobronchial lesions. DESIGN: A prospective, controlled, randomized study. SETTING: An operating theater of a respiratory endoscopy and laser therapy unit. POPULATION AND INTERVENTION: Twenty-seven consecutive patients referred to LT were entered into the study. Fourteen patients were randomly assigned to LT under general anesthesia and spontaneous assisted ventilation (control group) whereas in 13 cases, NPV by a poncho-wrap ventilator (NPV group) was added to the procedure. MEASUREMENTS AND RESULTS: The prevalence and the duration of apnea/hypopnea periods assessed by respiratory inductive plethysmography during LT were significantly reduced under NPV, compared to the control group. As compared to baseline, during LT, all control patients developed mild to severe hypercapnia (PaCO2 ranging from 55 to 76 mm Hg) and respiratory acidosis (pH from 7.33 to 7.19), whereas only three patients undergoing NPV (23%) developed hypercapnia (PaCO2 from 52 to 68 mm Hg) and related acidosis (pH from 7.29 to 7.21). Optimal oxygenation was achieved in all of the patients; nevertheless, patients under NPV needed a lower mean oxygen supply; five of them (38%) could be treated at a fraction of inspired oxygen of 0.21 for the whole procedure. CONCLUSION: NPV may be useful in reducing apneas during laser therapy under general anesthesia, thus reducing hypercapnia, related acidosis, and need of oxygen supplementation.

Effect of negative pressure ventilation on ventilatory muscle endurance in patients with severe chronic obstructive pulmonary disease.

We studied five men with chronic obstructive pulmonary disease (COPD) (mean age, 65 +/- SEM 2 yr; FEV1, 0.68 +/- 0.08 L; and FEV1/FVC, 38 +/- 2%) to determine the relationship between ventilatory muscle endurance (VME) and ventilatory muscle rest (VMR) elicited by negative-pressure ventilation (NPV). VME was measured as the maximal sustainable ventilation (MSVC) that the subjects could maintain for 12 min. Prior to therapy, MSVC for the subjects was 25.0 +/- 3.6 L/min. During the therapy phase, subjects received 4 wk of daily "in-hospital-supervised" NPV therapy (4 h/day). While subjects received therapy, we quantified VMR by (1) the percentage of breaths that were "in synchrony" and by (2) the percentage of breaths showing "turn-off" of the diaphragmatic EMG signal (EMGdl). During the therapy sessions, 93 +/- 2% of breaths were in synchrony, whereas 66 +/- 11% showed EMGdl turn-off. During post-therapy testing, an increase in MSVC was noted in each of the subjects; the mean increase was 4.0 +/- 1.3 L/min (p less than 0.05), which represented an increase of 16 +/- 4% over pretherapy values. Increases in MSVC were highly correlated with both the percentage of in-synchrony breaths (r = 0.96, p less than 0.01) and the percentage of breaths showing EMGdl turn-off (r = 0.92, p less than 0.02). However, NPV therapy elicited no other improvements in either clinical or laboratory measurements. Moreover, patients exhibited marked dyspnea with initiation and termination of daily NPV therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Negative-pressure ventilation.

In this review, we make the following major points: (1) Canine experiments indicate that in an experimental model of ARDS, cyclic NPV plus NEEP is as effective as cyclic PPV plus PEEP in treating arterial hypoxemia. Because cyclic NPV plus NEEP does not depress cardiac output as much as cyclic PPV plus PEEP, further study of this potential therapy is warranted. (2) At the present time, NPV has little use in neonatal medicine. (3) However, in adult medicine, NPV is efficacious for providing chronic ventilatory support in patients with neuromuscular and chest wall diseases. Additionally, the role of NPV in postoperative weaning warrants further study. (4) Some data in the literature suggest that some subsets of patients with CAL may benefit from chronic intermittent NPV therapy. However, criteria for identifying these patients have not been established. (5) Some investigators have recently demonstrated that PPV delivered via the nares can elicit VMR. Because this technique provides us with the opportunity to elicit VMR by a method other than NPV, nasal PPV provides us with a method to directly validate our presumption that improvements in COPD patients are related to VMR per se.