Sequential changes of hemodynamics and blood gases in newborn piglets with developing pneumothorax

Experimentally Induced Open Pneumothorax in Horses

The objective of this study was to evaluate clinical and cardiovascular parameters and pleural and intra-abdominal pressures of horses after experimentally induced unilateral open pneumothorax. Prospective, experimental study-animals: seven healthy adult horses, 4 females and 3 males. Left hemithorax thoracotomy was carried out to create an open pneumothorax for 60 minutes. Pleural pressure (P_pl) was directly obtained at the midpoint of the left eighth intercostal space before thoracotomy. Esophageal pressure (P_es), arterial blood gas analysis, left ventricular function, and ultrasonographic assessment of pneumothorax extent/resolution were performed at the baseline, and 5, 10, 15, 30, 45, and 60 minutes after thoracotomy, and on the first, second, third, fifth, and seventh days postoperatively. Intra-abdominal pressure was only recorded while the pneumothorax was present. There was moderate correlation (Spearman's rs = 0.404; R² = 0.8; P < .00001; Bland-Altman bias = -2.59; s.d. = 2.11) between P_es and P_pl. Esophageal pressure increased (P < .05) after open pneumothorax until the fifth day postoperatively. Partial pressure of oxygen in arterial blood reduced (P < .05) until the third day postoperatively when it returned to the baseline. No significant variations in P_aCO₂, pH in arterial blood, and in left ventricular function were appreciated. The extent of the pneumothorax was assessed by thoracic ultrasonography. Esophageal pressure, in association with blood gas analysis and thoracic ultrasonography, could be used to aid diagnosis of pneumothorax in horses. Horses tolerate open pneumothorax, with minimum cardiovascular impairment, even without aspiration of free air from within pleural space to restore thoracic wall integrity.

An innovative nonanimal simulation trainer for chest tube insertion in neonates

BACKGROUND AND OBJECTIVE

Competence in the chest tube insertion procedure is vital for practitioners who take care of critically ill infants. The use of animals for training is discouraged, and there are no realistic simulation models available for the neonatal chest tube insertion procedure. The objective of this study was to assess the effectiveness of teaching the chest tube insertion procedure by using an easily constructed, nonanimal simulation model.

METHODS

An inexpensive infant chest tube insertion model was developed by using simple hardware. A prospective cohort study with pre-posttest intervention design was conducted with pediatric and combined internal medicine-pediatrics residents. Residents completed a questionnaire about their previous experience of chest tube insertion, knowledge, self-evaluation of knowledge, comfort, and skills; pre, post, and a month after an individualized education session and demonstration of the procedure on the model. Clinical skills were assessed by using a 32-point scoring system when residents performed the procedure on the model immediately after training and a month later.

RESULTS

All residents had significant improvement in knowledge and self-evaluation of knowledge, comfort, and skills scores after the education session and training on the model and this improvement was retained after 1 month (P < .001). Clinical skills scores decreased slightly 1 month after training (P = .08). Scores were not significantly different between the levels of trainees.

CONCLUSIONS

An educational intervention using an easily constructed and inexpensive chest tube insertion model is effective in improving knowledge, comfort, and skills in trainees. The model can be used repeatedly to maintain proficiency.

Highly sensitive monitoring of chest wall dynamics and acoustics provides diverse valuable information for evaluating ventilation and diagnosing pneumothorax

Current practice of monitoring lung ventilation in neonatal intensive care units, utilizing endotracheal tube pressure and flow, end-tidal CO2, arterial O2 saturation from pulse oximetry, and hemodynamic indexes, fails to account for asymmetric pathologies and to allow for early detection of deteriorating ventilation. This study investigated the utility of bilateral measurements of chest wall dynamics and sounds, in providing early detection of changes in the mechanics and distribution of lung ventilation. Nine healthy New Zealand rabbits were ventilated at a constant pressure, while miniature accelerometers were attached to each side of the chest. Slowly progressing pneumothorax was induced by injecting 1 ml/min air into the pleural space on either side of the chest. The end of the experiment ( tPTX) was defined when arterial O2 saturation from pulse oximetry dropped <90% or when vigorous spontaneous breathing began, since it represents the time of clinical detection using common methods. Consistent and significant changes were observed in 15 of the chest dynamics parameters. The most meaningful temporal changes were noted for features extracted from subsonic dynamics (<10 Hz), e.g., tidal amplitude, energy, and autoregressive poles. Features from the high-frequency band (10–200 Hz), e.g., energy and entropy, exhibited smaller but significant changes. At 70% tPTX, identification of asymmetric ventilation was attained for all animals. Side identification of the pneumothorax was achieved at 50% tPTX, within a 95% confidence interval. Diagnosis was, on average, 34.1 ± 18.8 min before tPTX. In conclusion, bilateral monitoring of the chest dynamics and acoustics provide novel information that is sensitive to asymmetric changes in ventilation, enabling early detection and localization of pneumothorax.