Drainage of pleural effusion in mechanically ventilated patients: time to measure chest wall compliance?

Management of pleural effusion in mechanically ventilated critically ill patients: A systematic review and guideline

BACKGROUND

Mechanically ventilated critically ill patients often develop pleural effusions, which may impact lung compliance and expansion. This systematic review explores the management of pleural effusion in the critically ill population.

METHODS

A comprehensive literature search was performed. Quality of evidence rating and recommendation development utilized Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology.

RESULTS

The full search retrieved 11,965 articles for screening, of which 28 studies ultimately met inclusion criteria. There were 15 cohort studies assessing oxygenation outcome and 17 cohort studies assessing pneumothorax outcome. Patients with drainage (n ​= ​418) had a pooled mean increase in PaO2/FiO2 ratio of 53 (P ​< ​0.00001, 95 ​% CI: 43-64, I2 ​= ​0 ​%) compared to pre-drainage/no-drainage (n ​= ​432). In patients with drainage, the combined incidence of pneumothorax was 124/5995 (2.1 ​%).

CONCLUSION

In mechanically ventilated critically ill adult patients with pleural effusion and hypoxia, we conditionally recommend drainage of pleural effusion to improve oxygenation. P:F ratio <200 and pleural effusion volume estimate >500 ​mL are conditions in which drainage would have most benefit.

Exploring ultrasonographic diaphragmatic function in perioperative anesthesia setting: A comprehensive narrative review

The ultrasound study of diaphragm function represents a valid method that has been extensively studied in recent decades in various fields, especially in intensive care, emergency, and pulmonology settings. Diaphragmatic function is pivotal in these contexts due to its crucial role in respiratory mechanics, ventilation support strategies, and overall patient respiratory outcomes. Dysfunction or weakness of the diaphragm can lead to respiratory failure, ventilatory insufficiency, and prolonged mechanical ventilation, making its assessment essential for patient management and prognosis in critical care and emergency medicine. While several studies have focused on diaphragmatic functionality in the context of intensive care, there has been limited attention within the field of anesthesia. The ultrasound aids in assessing diaphragmatic dysfunction (DD) by measuring muscle mass and contractility and their potential variations over time. Recent advancements in ultrasound imaging allow clinicians to evaluate diaphragm function and monitor it during mechanical ventilation more easily. In the context of anesthesia, early studies have shed light on the patho-physiological mechanisms of diaphragm function during general anesthesia. In contrast, more recent research has centered on evaluating diaphragmatic functionality at various phases of general anesthesia and by comparing diverse types of procedures or anatomical position during surgery. The objectives of this current review are to highlight the use of diaphragm ultrasound for the evaluation of diaphragmatic function during perioperative anesthesia and surgery. Specifically, we aim to examine the effects of anesthetic agents, surgical techniques, and anatomical positioning on diaphragmatic function. We explore how ultrasound aids in assessing DD by measuring muscle mass and contractility, as well as their potential variations over time. Additionally, we will discuss recent advancements in ultrasound imaging that allow clinicians to evaluate diaphragm function and monitor it during mechanical ventilation more easily.

Breathlessness with Pleural Effusion: What Do We Know?

Breathlessness is the most common symptom in individuals with pleural effusion and is often disabling. The pathophysiology of breathlessness associated with pleural effusion is complex. The severity of breathlessness correlates weakly with the size of the effusion. Improvements in ventilatory capacity following pleural drainage are small and correlate poorly with the volume of fluid drained and improvements in breathlessness. Impaired hemidiaphragm function and a compensatory increase in respiratory drive to maintain ventilation appear to be an important mechanism of breathlessness associated with pleural effusion. Thoracocentesis reduces diaphragm distortion and improves its movement; these changes appear to reduce respiratory drive and associated breathlessness by improving the neuromechanical efficiency of the diaphragm.

Body Position Alters Mechanical Power and Respiratory Mechanics During Thoracic Surgery

BACKGROUND

During thoracic surgery, patients are usually positioned in lateral decubitus and only the dependent lung ventilated. The ventilated lung is thus exposed to the weight of the contralateral hemithorax and restriction of the dependent chest wall. We hypothesized that mechanical power would increase during one-lung ventilation in the lateral position.

METHODS

We performed a prospective, observational, single-center study from December 2016 to May 2017. Thirty consecutive patients undergoing general anesthesia with mechanical ventilation (mean age, 68 ± 11 years; body mass index, 25 ± 5 kg·m) for thoracic surgery were enrolled. Total and partitioned mechanical power, lung and chest wall elastance, and esophageal pressure were compared in supine and lateral position with double- and one-lung ventilation and with closed and open chest both before and after surgery. Mixed factorial ANOVA for repeated measurements was performed, with both step and the period before or after surgery as 2 within-subject factors, and left or right body position during surgery as a fixed, between-subject factor. Appropriate interaction terms were included.

RESULTS

The mechanical power was higher in lateral one-lung ventilation compared to both supine and lateral position double-lung ventilation (11.1 ± 3.0 vs 8.2 ± 2.7 vs 8.7 ± 2.6; mean difference, 2.9 J·minute [95% CI, 1.4-4.4 J·minute] and 2.4 J·minute [95% CI, 0.9-3.9 J·minute]; P < .001 and P = .002, respectively). Lung elastance was higher during lateral position one-lung ventilation compared to both lateral and supine double-lung ventilation (24.3 ± 8.7 vs 9.5 ± 3.8 vs 10.0 ± 3.8; mean difference, 14.7 cm H2O·L [95% CI, 11.2-18.2 cm H2O·L] and 14.2 cm H2O·L [95% CI, 10.8-17.7 cm H2O·L], respectively) and was higher compared to predicted values (20.1 ± 7.5 cm H2O·L). Chest wall elastance increased in lateral position double-lung ventilation compared to supine (11.1 ± 3.8 vs 6.6 ± 3.4; mean difference, 4.5 cm H2O·L [95% CI, 2.6-6.3 cm H2O·L]) and was lower in lateral position one-lung ventilation with open chest than with a closed chest (3.5 ± 1.9 vs 7.1 ± 2.8; mean difference, 3.6 cm H2O·L [95% CI, 2.4-4.8 cm H2O·L]). The end-expiratory esophageal pressure decreased moving from supine position to lateral position one-lung ventilation while increased with the opening of the chest wall.

CONCLUSIONS

Mechanical power and lung elastance are increased in the lateral position with one-lung ventilation. Esophageal pressure monitoring may be used to follow these changes.

Effects of pleural drainage on oxygenation in critically ill patients

Aim

Pleural effusion is common among critically ill patients and associated with clinical consequences; however, the benefits of draining pleural effusion remain debatable. Thus, we aimed to investigate pleural drainage effectiveness by focusing on preprocedure patient status.

Methods

We retrospectively analyzed 22 patients with pleural effusion. Gas exchange, ventilator settings, vital signs, inflammatory response, and nutrition status were examined preprocedure and 24 h and 1 week postprocedure. Data were analyzed using the non‐parametric test and discriminant analysis with receiver operating characteristic curves.

Results

The partial arterial oxygen pressure (PaO₂) to fraction of inspiratory oxygen (F_IO₂) (P/F) ratio at 24 h was higher postdrainage than predrainage (250 ± 87 versus 196 ± 84, P < 0.05); however, no significant difference between the P/F ratio predrainage and 1 week postdrainage was noted. Patients were classified into effective and ineffective groups according to a 110% increase in the P/F ratio 1 week postdrainage compared with predrainage. The predrainage P/F ratio was lower in the effective group than in the ineffective group (165 ± 91 versus 217 ± 74, P < 0.05). Discriminant analysis showed the area under the receiver operating characteristic curve was 0.72; the cut‐off value of the predrainage P/F ratio (divided into effective and ineffective groups) was 174.

Conclusions

Pleural drainage could be effective in patients who have lower preprocedure P/F ratios.

Utility of pleural effusion drainage in the ICU: An updated systematic review and META-analysis

PURPOSE

The effects on the respiratory or hemodynamic function of drainage of pleural effusion on critically ill patients are not completely understood. First outcome was to evaluate the PiO₂/FiO₂ (P/F) ratio before and after pleural drainage.

SECONDARY OUTCOMES

evaluation of A-a gradient, End-Expiratory lung volume (EELV), heart rate (HR), mean arterial pressure (mAP), left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (CO), ejection fraction (EF), and E/A waves ratio (E/A). A tertiary outcome: evaluation of pneumothorax and hemothorax complications.

MATERIALS AND METHODS

Searches were performed on MEDLINE, EMBASE, COCHRANE LIBRARY, SCOPUS and WEB OF SCIENCE databases from inception to June 2018 (PROSPERO CRD42018105794).

RESULTS

We included 31 studies (2265 patients). Pleural drainage improved the P/F ratio (SMD: -0.668; CI: -0.947-0.389; p < .001), EELV (SMD: -0.615; CI: -1.102-0.219; p = .013), but not A-a gradient (SMD: 0.218; CI: -0.273-0.710; p = .384). HR, mAP, LVEDV, SV, CO, E/A and EF were not affected. The risks of pneumothorax (proportion: 0.008; CI: 0.002-0.014; p = .138) and hemothorax (proportion: 0.006; CI: 0.001-0.011; p = .962) were negligible.

CONCLUSIONS

Pleural effusion drainage improves oxygenation of critically ill patients. It is a safe procedure. Further studies are needed to assess the hemodynamic effects of pleural drainage.

In patients with unilateral pleural effusion, restricted lung inflation is the principal predictor of increased dyspnoea

BACKGROUND AND OBJECTIVE

The mechanism of dyspnoea associated with pleural effusion is uncertain. A cohort of patients requiring thoracoscopy for unilateral exudative effusion were investigated for associations between dyspnoea and suggested predictors: impaired ipsilateral diaphragm movement, effusion volume and restricted lung inflation.

METHODS

Baseline Dyspnoea Index, respiratory function, and ultrasound assessment of ipsilateral diaphragm movement were assessed prior to thoracoscopy, when effusion volume was measured. Transitional Dyspnoea Index (change from baseline) was assessed 4 and 8 weeks after thoracoscopy. Pearson product moment assessed bivariate correlations and a general linear model examined how well total lung capacity (measuring restricted lung inflation), effusion volume and impaired diaphragm movement predicted Baseline Dyspnoea Index. Un-paired t tests compared the groups with normal and impaired diaphragm movement.

RESULTS

19 patients were studied (14 malignant etiology). Total lung capacity was associated with Baseline Dyspnoea Index (r = 0.68, P = 0.003). Effusion volume (r = -0.138, P = 0.60) and diaphragm movement (P = 0.09) were not associated with Baseline Dyspnoea Index. Effusion volume was larger with impaired diaphragm movement compared to normal diaphragm movement (2.16 ±SD 0.95 vs.1.16 ±0.92 L, P = 0.009). Total lung capacity was lower with impaired diaphragm movement compared to normal diaphragm movement (65.4 ±10.3 vs 78.2 ±8.6% predicted, P = 0.011). The optimal general linear model to predict Baseline Dyspnoea Index used total lung capacity alone (adjusted R2 = 0.42, P = 0.003). In nine participants with controlled effusion, baseline effusion volume (r = 0.775, P = 0.014) and total lung capacity (r = -0.690, P = 0.040) were associated with Transitional Dyspnoea Index.

CONCLUSIONS

Restricted lung inflation was the principal predictor of increased dyspnoea prior to thoracoscopic drainage of effusion, with no independent additional association with either effusion volume or impaired ipsilateral diaphragm movement. Restricted lung inflation may be an important determinant of the dyspnoea associated with pleural effusion.

Reliability of transpulmonary pressure-time curve profile to identify tidal recruitment/hyperinflation in experimental unilateral pleural effusion

The stress index (SI) is a parameter that characterizes the shape of the airway pressure-time profile (P/t). It indicates the slope progression of the curve, reflecting both lung and chest wall properties. The presence of pleural effusion alters the mechanical properties of the respiratory system decreasing transpulmonary pressure (Ptp). We investigated whether the SI computed using Ptp tracing would provide reliable insight into tidal recruitment/overdistention during the tidal cycle in the presence of unilateral effusion. Unilateral pleural effusion was simulated in anesthetized, mechanically ventilated pigs. Respiratory system mechanics and thoracic computed tomography (CT) were studied to assess P/t curve shape and changes in global lung aeration. SI derived from airway pressure (Paw) was compared with that calculated by Ptp under the same conditions. These results were themselves compared with quantitative CT analysis as a gold standard for tidal recruitment/hyperinflation. Despite marked changes in tidal recruitment, mean values of SI computed either from Paw or Ptp were remarkably insensitive to variations of PEEP or condition. After the instillation of effusion, SI indicates a preponderant over-distension effect, not detected by CT. After the increment in PEEP level, the extent of CT-determined tidal recruitment suggest a huge recruitment effect of PEEP as reflected by lung compliance. Both SI in this case were unaffected. We showed that the ability of SI to predict tidal recruitment and overdistension was significantly reduced in a model of altered chest wall-lung relationship, even if the parameter was computed from the Ptp curve profile.