Respiratory Care

Cervical spinal cord injury (CSCI) often results in respiratory muscle weakness, requiring prolonged mechanical ventilation and tracheostomy. However, the frequency and timing of ventilator-weaning milestones after acute hospitalization are not well described. This study assessed the rates and timing of daytime ventilator weaning, liberation from invasive ventilator support, and decannulation among adults with CSCI managed under a standardized weaning protocol at a rehabilitation center, and the associations of weaning milestones with discharge disposition.

We retrospectively analyzed data from adults with CSCI admitted to the University of Utah Craig H. Neilsen Rehabilitation Hospital between 2015 and 2022. All subjects required continuous mechanical ventilation via tracheostomy upon admission and underwent a standardized ventilator weaning protocol. We tracked the time to reach key ventilator-weaning milestones—daytime wean, liberation from invasive mechanical ventilation, and decannulation—and categorized discharge destinations based on required respiratory support intensity. Predictors of milestone achievement and discharge outcomes were assessed using Fine-Gray competing-risk and proportional odds logistic regression models.

Among 39 subjects, 76% were weaned from daytime ventilator support (median day 20), 62% were liberated from invasive ventilatory support (median day 23), and 48% were decannulated (median day 36) by discharge. Subjects with lower-level injuries (C5–C8) were more likely to achieve further weaning and decannulation compared with those with high-level injuries (C1–C4) (odds ratio [OR] 5.54 [1.51–20.38]). Increasing age was associated with discharge to more intensive care settings (OR 0.68 per decade [0.48–0.95]). Decannulated subjects had higher odds of being discharged home (OR 22.84 [2.84–183.57]). No significant differences in weaning status based on discharge disposition were observed.

Most subjects with CSCI initially on continuous mechanical ventilation achieved partial or full ventilatory independence during rehabilitation, although these milestones were often reached several weeks into their stay.

Surgical and N95 masks are commonly used in the prevention of respiratory virus transmission. The safety of wearing masks is well documented in healthy individuals but is unclear in people with chronic hypercapnia. In addition, masks are often poorly tolerated in this population. The present study assessed the effect of surgical and N95 masks in people with stable chronic hypercapnia using noninvasive ventilation (NIV).

A randomized crossover trial was performed. S pO 2 and transcutaneous CO₂ ( P tcCO 2 ) were measured in participants wearing a surgical mask, an N95 mask, and no mask for a 20-min period at rest. Secondary outcomes included heart rate, breathing frequency, the A1 scale from the Multidimensional Dyspnea Profile (MDP), and the modified Borg dyspnea scale (mBORG).

24 participants (50% female; mean [SD] age 61 [13] years) were randomized and completed data collection. Over the 20-min study period, when compared with no mask, the mean differences for S pO 2 in surgical and N95 masks were 0.0% [95% CI: −1.0–0.9] and 0.3% [95% CI: −0.6–1.3]. For P tcCO 2 surgical mask, the mean difference was 0.0 mm Hg [95% CI: −1.3–1.3], and for N95 mask, the mean difference was 1.0 mm Hg [95% CI: 0.3–2.3]. There was no effect on heart rate or breathing frequency. Masks increased the mBORG (surgical mask median difference 0.75 points [95% CI: 0.25–2.00]; N95 mask median difference 1.50 [95% CI: 0.75–2.25]) and MDP (surgical mask median difference 1.5 points [95% CI: 0.5–2.5]; N95 mask median difference 2.5 points [95% CI: 1.0–3.0]) compared with no mask. Three participants requested to remove one or both masks early.

Wearing a surgical mask and N95 mask did not significantly affect gas exchange in subjects with chronic hypercapnia using NIV. However, dyspnea and breathing discomfort did increase.

It has been suggested that the implementation of protective mechanical ventilation may increase respiratory acidosis when other ventilator settings, including breathing frequency, are not optimized. After cardiac surgery, this complication may be associated with hemodynamic impact, such as pulmonary hypertension. VentilO is a clinical-decision support system developed to implement protective ventilation. The primary objective of this study was to evaluate the incidence of acid/base disorders after cardiac surgery and to compare the ventilatory parameters set by the clinicians with those proposed by VentilO. This is the first step in validating the VentilO algorithm.

We conducted a retrospective analysis of the first 100 subjects admitted to the ICU after cardiac surgery in 2023. We recorded demographic and surgical data, the first arterial blood gas at the time of arrival in the ICU, the actual ventilator settings, and the settings recommended by the VentilO algorithm. We compared the minute ventilation and ventilatory parameters set by clinicians with those proposed by VentilO using one-way analysis of variance and Wilcoxon rank-sum test.

The prevalence of respiratory acidosis (pH <7.35 and P_aCO2 >45 mm Hg) was 38%. Acidosis was associated with the use of lower tidal volumes (56% at 8 mL/kg predicted body weight versus 85% at 6 mL/kg predicted body weight, P = .039). VentilO proposed a higher minute ventilation than what was set by the clinicians for 94/100 subjects (8.4 ± 1.3 vs 6.1 ± 1.2 L/min; P < .001). The mean increase in breathing frequency proposed by VentilO was 5 breaths/min (18 ± 3 vs 13 ± 2 breaths/min, P < .001).

The incidence of respiratory acidosis is high after cardiac surgery and may be lessened using a clinical-decision support system to set postoperative ventilatory parameters.

To investigate obstructive sleep apnea (OSA) prevalence, associated comorbidities, distribution of respiratory events in different sleep states, and body positions in infants.

This was a single-center retrospective study that included infants aged 0 to 12 months who underwent polysomnogram (PSG). OSA severity was categorized by obstructive apnea-hypopnea index (OAHI) as mild (1–4.9 events/h), moderate (5–9.9 events/h), and severe (≥10 events/h).

One hundred eighteen infants were included with a median age of 5 months (interquartile range, [IQR] 2.0–9.0) for the OSA group (73/118) and 7 months (IQR 6.0–9.0) for the non-OSA group (45/118) (P = .01). The most common indication for PSG was snoring (57.5%), followed by apneas (41.1%). OSA prevalence was 61.9% (53.4% mild, 17.8% moderate, and 28.8% severe). Gastroesophageal reflux disease (GERD; 32.9%) and 21.9% of craniofacial abnormalities were commonly associated comorbidities. Multivariate binominal regression analysis indicated that infants with a history of craniofacial abnormalities (P = .038) had higher odds of having OSA. There were no significant differences noted in sleep architecture medians, such as total sleep time, sleep efficiency, sleep latency, stage 1, 2, 3, and rapid eye movement (REM) sleep durations, between the OSA and the non-OSA group, except for the median arousal index, which was significantly higher in the OSA group (15.7 [11.9, 24.1] versus 10.6 [9.4, 16.3]; P < .001). Differences in respiratory parameters including apnea hypopnea index (AHI), OAHI, REM AHI, non-REM AHI, S_pO2 nadir and mean, and carbon dioxide mean and peak were significant. In 6–12-month-olds, 32 infants with OSA had REM AHI that was higher than non-REM (AHI: 17.0 [10.9, 33.8] versus 2.3 [0.6, 6.0]; P < .001). Similarly, supine AHI was higher (P < .001) when we compared it with each non-supine positions individually.

In infants, OSA was highly prevalent in our cohort; a history of GERD and craniofacial abnormalities were commonly associated comorbidities. Obstructive events occurred predominantly in REM sleep and the supine position.

Ventilatory ratio (VR) is a surrogate marker of dead-space fraction that is increasingly used to assess ventilation impairment and predict clinical outcomes. However, the current VR equation uses on predicted body weight (PBW) to estimate reference minute ventilation, which may lead to an overestimation of dead-space fraction in patients with extreme body weights. We hypothesized that VR calculated using PBW and actual body weight (ABW) might differ in their ability to predict outcomes, particularly in obese patients.

This retrospective study compared the discrimination capacity of PBW-estimated VR (pVR), ABW-estimated VR (aVR), and corrected minute ventilation (V_Ecorr) for a composite outcome of death or weaning failure at ICU discharge across three body weight categories: underweight, normal-to-overweight, and obese. The area under the receiver operating characteristic curve (AUROC) was used to assess the discrimination capacity of the study outcome.

A total of 4,015 subjects who received mechanical ventilation were included. The primary composite outcome events occurred in 40.6% of subjects, including a mortality rate of 29.1%. In underweight subjects, no significant differences in discrimination capacity were observed among pVR, aVR, and V_Ecorr (AUROC, 0.599, 0.598, 0.595, P = .92). In normal-to-overweight subjects, aVR outperformed V_Ecorr (AUROC, 0.582 vs 0.571, P = .02), while pVR did not (AUROC, 0.576 vs 0.571, P = .39). In obese subjects, both aVR and V_Ecorr outperformed pVR (AUROC 0.559 vs 0.520, P = .003; and AUROC 0.557 vs 0.520, P = .041).

In nonobese subjects, there was no significant difference between using PBW and ABW to calculate VR for outcome prediction. However, in obese subjects, using ABW was associated with better predictive validity than using PBW. These findings suggest that PBW-based VR may be less reliable than ABW-based VR for assessing ventilation impairment in patients with higher body weight.

Interstitial lung abnormalities (ILAs) progress radiologically in many patients and may reflect early interstitial lung disease (ILD). Within idiopathic pulmonary fibrosis and other smoking-related ILDs, there is increasing evidence that aberrant airway biology plays a role in disease development and progression. In this study, we sought to investigate associations between radiologic features of airways disease and progressive ILAs that could provide valuable insights into the management of patients at risk for developing ILD.

We performed a retrospective study of subjects undergoing low-dose computed tomography (LDCT) for lung cancer screening between January 2016 and August 2022. Adults aged 50–80 years with ≥2 LDCTs performed ≥24 months apart were included. Demographic data, medical history, and LDCTs were collected. LDCTs were qualitatively analyzed for ILAs and features of airways disease by a thoracic radiologist. Data were analyzed using a generalized estimating equation adjusted for age, sex, pack-years of tobacco, and a radiologic usual interstitial pneumonia pattern.

Of 482 subjects, 54% (259/482) were female, and 66% (316/482) were Black. Average age was 64 years. The majority of subjects were current smokers (n = 276, 57%). Thirty-one percent (n = 147) had COPD, and 11% had asthma (n = 56). Median time between LDCTs was 51 (39–61) months. There were 85 subjects with ILAs, and of those, 42 (49.4%) had progressive ILAs. Bronchial wall thickening and mosaic attenuation were associated with ILA progression in adjusted models (odds ratio [OR] = 2.61, 95% CI: 1.08–6.23 and OR = 2.51, 95% CI: 1.02–6.17, respectively).

Radiologic features of airways disease, including bronchial wall thickening and mosaic attenuation, were associated with ILA progression in subjects undergoing lung cancer screening.

Prone positioning is a recommended therapy for patients with moderate-to-severe ARDS; however, the optimal duration of this maneuver is still unknown.

We performed a systematic review and meta-analysis comparing clinical outcomes of extended (≥24 h) versus traditional prone positioning (16–24 h) of adults with moderate-to-severe ARDS receiving invasive mechanical ventilation.

Ten studies involving 2,412 subjects met the inclusion criteria, including one randomized controlled trial and 9 observational studies, all with COVID-19-related ARDS. Extended prone positioning was associated with reduced mortality compared with the traditional approach (risk ratio [RR]: 0.76, 95% CI 0.66–0.86, I² = 12.8%). Sensitivity and subgroup analyses confirmed consistency across risk of bias, baseline P_aO2/F_iO2, and PEEP levels. No differences were found in duration of mechanical ventilation (mean difference [MD]: 2.43 days, 95% CI −1.06 to 5.92, I² = 70%) or ICU stay (MD: 1.31 days, 95% CI −1.07 to 3.68, I² = 55%). The extended strategy was associated with a higher incidence of pressure injuries (RR: 1.30, 95% CI 1.02–1.65, I² = 56%) but no differences in device displacement or hemodynamic instability. Certainty of evidence was rated as low to very low.

Extended prone positioning was associated with reduced mortality in ARDS but increased risk of pressure injuries, without impact on ventilator duration or ICU stay. While this strategy appears feasible and potentially beneficial, further randomized trials are warranted to confirm its role in routine practice.

PROSPERO no. CRD42024529311.