Supplemental oxygen improves resolution of injury-induced pneumothorax

"Nitrogen Wash-Out" in Non-Hypoxaemic Patients with Spontaneous Pneumothorax: A Narrative Review

Following current guidelines, spontaneous pneumothorax should be primarily managed with minimal invasive strategies. In real-world clinical practice, oxygen supplementation regardless of the presence or absence of hypoxemia is frequently applied in patients with a pneumothorax, with the intention to enhance the resorption rate of air from the pleural cavity ("nitrogen wash-out theory"). This review provides an overview of the scientific origin of this practice in animal models, and its clinical use in adult and paediatric patients. Clinical studies from PubMed, Embase and Cochrane library were reviewed by the authors using the keywords, "oxygen AND pneumothorax", "nitrogen washout AND pneumothorax" and "nitrogen AND pneumothorax", and recommendations from current guidelines were also reviewed by the authors. A selected total of nine clinical studies and three guidelines were included. Though in animal models there appears to be a therapeutic effect of oxygen therapy for the treatment of pneumothorax, clinical data in patient populations mainly stem from retrospective studies, mostly with a small sample size and inadequate study design. We recommend conducting prospective clinical studies with adequate methodology to address the question of whether or not oxygen therapy should be used to treat pneumothorax, regardless of the presence or absence of hypoxemia.

Does oxygen therapy increase the resolution rate of primary spontaneous pneumothorax?

Background

Patients with small pneumothoraces are usually treated with oxygen therapy. However, evidence that oxygen therapy increases resolution rate is based on small populations with secondary spontaneous pneumothorax. Therefore, this study aimed to confirm whether oxygen therapy increases the resolution rate of primary spontaneous pneumothorax (PSP).

Methods

We retrospectively reviewed records of patients with PSP who had undergone outpatient observation (room air group) and those who were admitted for oxygen therapy (O₂ group) between March 2005 and February 2016. The initial chest posteroanterior (PA) radiograph was compared with the last chest PA radiograph before the pneumothorax disappeared. The size of the pneumothorax was measured using the Collins' method.

Results

A total of 175 episodes were identified in 160 patients. Of these, 128 episodes (73.1%) occurred in patients in the O₂ group. The mean age was 19.24±4.74 years. The mean initial size of the pneumothorax was smaller in the room air group (23.32%±7.00% vs. 20.26%±6.78%, P=0.011). The resolution rate was higher in the O₂ group [(4.27%±1.97%) vs. (2.06%±0.97%)/day, P<0.001]. The initial size of the pneumothorax, time interval between radiographs, and use of oxygen therapy were significantly associated with the resolution rate in multivariate analysis.

Conclusions

Oxygen therapy increases the resolution rate of PSP. However, routine use of oxygen therapy in patients with small pneumothoraces should be considered more carefully. Well-controlled prospective studies are required to confirm the indication of oxygen therapy.

Traumatic tension pneumocephalus - Two cases and comprehensive review of literature

Although traumatic pneumocephalus is not uncommon, it rarely evolves into tension pneumocephalus (TP). Characterized by the presence of increasing amounts of intracranial air and concurrent appearance or worsening neurological symptoms, TP can be devastating if not recognized and treated promptly. We present two cases of traumatic TP and a concise review of literature on this topic. Two cases of traumatic TP are presented. In addition, a literature search revealed 20 additional cases, of which 18 had sufficient information for inclusion. Literature cases were combined with the 2 reported cases and analyzed for demographics, mechanism of injury, symptoms, time to presentation (acute <72 h; delayed >72 h), diagnostic/treatment modalities, and outcomes. Twenty cases were analyzed (17 males, 3 females, median age 26, range 8–92 years). Presentation was acute in 13/20 and delayed in 7/20 patients. Injury mechanisms included motor vehicle collisions (6/20), assault/blunt trauma to the craniofacial area (5), falls (4), and motorcycle/ bicycle crashes (3). Common presentations included depressed mental status (10/20), cerebrospinal fluid rhinorrhea (9), headache (8), and loss of consciousness (6). Computed tomography (CT) was utilized in 19/20 patients. Common underlying injuries were frontal bone/sinus fracture (9/20) and ethmoid fracture (5). Intracranial hemorrhage was seen in 5/20 patients and brain contusions in 4/20 patients. Nonoperative management was utilized in 6/20 patients. Procedural approaches included craniotomy (11/20), emergency burr hole (4), endoscopy (2), and ventriculostomy (2). Most patients responded to initial treatment (19/20). One early and one delayed death were reported. Traumatic TP is rare, tends to be associated with severe craniofacial injuries, and can occur following both blunt and penetrating injury. Early recognition and high index of clinical suspicion are important. Appropriate treatment results in improvement in vast majority of cases. CT scan is the diagnostic modality of choice for TP.

Thoracic trauma in horses

Traumatic injuries involving the thorax can be superficial, necessitating only routine wound care, or they may extend to deeper tissue planes and disrupt structures immediately vital to respiratory and cardiac function. Diagnostic imaging, especially ultrasound, should be considered part of a comprehensive examination, both at admission and during follow-up. Horses generally respond well to diligent monitoring, intervention for complications, and appropriate medical or surgical care after sustaining traumatic wounds of the thorax. This article reviews the various types of thoracic injury and their management.

Impact of oxygen concentration on time to resolution of spontaneous pneumothorax in term infants: a population based cohort study

Background

Little evidence exists regarding the optimal concentration of oxygen to use in the treatment of term neonates with spontaneous pneumothorax (SP). The practice of using high oxygen concentrations to promote “nitrogen washout” still exists at many centers. The aim of this study was to identify the time to clinical resolution of SP in term neonates treated with high oxygen concentrations (HO: FiO₂ ≥ 60%), moderate oxygen concentrations (MO: FiO₂ < 60%) or room air (RA: FiO₂ = 21%).

Methods

A population based cohort study that included all term neonates with radiologically confirmed spontaneous pneumothorax admitted to all neonatal intensive care units in Calgary, Alberta, Canada, within 72 hours of birth between 2006 and 2010. Newborns with congenital and chromosomal anomalies, meconium aspiration, respiratory distress syndrome, and transient tachypnea of newborn, pneumonia, tension pneumothorax requiring thoracocentesis or chest tube drainage or mechanical ventilation before the diagnosis of pneumothorax were excluded. The primary outcome was time to clinical resolution (hours) of SP. A Cox proportional hazards model was developed to assess differences in time to resolution of SP between treatment groups.

Results

Neonates were classified into three groups based on the treatment received: HO (n = 27), MO (n = 35) and RA (n = 30). There was no significant difference in time to resolution of SP between the three groups, median (range 25th-75th percentile) for HO = 12 hr (8–27), MO = 12 hr (5–24) and RA = 11 hr (4–24) (p = 0.50). A significant difference in time to resolution of SP was also not observed after adjusting for inhaled oxygen concentration [MO (a HR = 1.13, 95% CI 0.54-2.37); RA (a HR = 1.19, 95% CI 0.69-2.05)], gender (a HR = 0.87, 95% CI 0.53-1.43) and ACoRN respiratory score (a HR = 0.7, 95% CI 0.41-1.34).

Conclusions

Supplemental oxygen use or nitrogen washout was not associated with faster resolution of SP. Infants treated with room air remained stable and did not require supplemental oxygen at any point of their admission.

Administration of 100% oxygen does not hasten resolution of symptomatic spontaneous pneumothorax in neonates

OBJECTIVE

To compare the effectiveness of 100% oxygen therapy vs oxygen treatment with targeted pulse oximetry in the management of symptomatic small to moderate spontaneous pneumothorax (SP). In total, 100% oxygen treatment for SP has been a common practice in neonatology, albeit there is little evidence to validate its efficacy.

STUDY DESIGN

A retrospective chart review of 83 neonatal records with the diagnosis of pneumothorax was conducted. Infants <35 weeks gestation, those with large pneumothoraces requiring chest tube drainage and/or ventilatory support were excluded. Data gathered included demographics, vital signs, treatment information and clinical indicators of resolution of symptoms.

RESULT

In total, 45 neonates with SP were included in the study. Groups were similar for gestational age, birth weight, Apgar scores, gravidity, parity, gender, race, pneumothorax size and location. Patients in the 100% oxygen therapy group received a significantly longer oxygen treatment (21.3 vs 8 h, P < 0.001), required longer intravenous fluid treatment (48.6 ± 29.9 vs 31.3 ± 18.8 h, P = 0.03) and were delayed in reaching full feeds (44.1 ± 25.7 vs 29.5 ± 18.8 h, P = 0.03) compared with the oxygen-targeted treatment group. Time to first oral feeding, time to resolution of tachypnea and length of stay were similar in both groups.

CONCLUSION

There are no clinically significant advantages to using 100% oxygen in the treatment of symptomatic small to moderate SP. In fact, it may result in longer exposure to unnecessary oxygen treatment and toxicity. Oxygen should be reserved for those who are hypoxic and adjusted to comply with accepted saturation levels in neonates.