Transthoracic impedance variability to assess quality of chest compression in out-of-hospital cardiac arrest.

BACKGROUND: Chest compression is a lifesaving intervention in out-of-hospital cardiac arrest (OHCA), but the optimal metrics to assess its quality have yet to be identified. The objective of this study was to investigate whether a new parameter, that is, the variability of the chest compression-generated transthoracic impedance (TTI), namely ImpCC , which measures the consistency of the chest compression maneuver, relates to resuscitation outcome. METHODS: This multicenter observational, retrospective study included OHCAs with shockable rhythm. ImpCC variability was evaluated with the power spectral density analysis of the TTI. Multivariate regression model was used to examine the impact of ImpCC variability on defibrillation success. Secondary outcome measures were return of spontaneous circulation and survival. RESULTS: Among 835 treated OHCAs, 680 met inclusion criteria and 565 matched long-term outcomes. ImpCC was significantly higher in patients with unsuccessful defibrillation compared to those with successful defibrillation (p = .0002). Lower ImpCC variability was associated with successful defibrillation with an odds ratio (OR) of 0.993 (95% confidence interval [95% CI], 0.989-0.998, p = .003), while the standard chest compression fraction (CCF) was not associated (OR 1.008 [95 % CI, 0.992-1.026, p = .33]). Neither ImpCC nor CCF was associated with long-term outcomes. CONCLUSIONS: In this population, consistency of chest compression maneuver, measured by variability in TTI, was an independent predictor of defibrillation outcome. ImpCC may be a useful novel metrics for improving quality of care in OHCA.

Short-term Physiologic Consequences of Regional Pulmonary Vascular Occlusion in Pigs.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: After pulmonary artery occlusion (mimicking a pulmonary embolism), perfusion is redistributed to the rest of the lung tissue, but the distribution of ventilation is uncertain. WHAT THIS ARTICLE TELLS US THAT IS NEW: Data from anesthetized pigs (uninjured lungs) indicate that the perfusion is redistributed as suspected. Similarly, ventilation is redistributed from nonperfused to perfused lung tissue. This limits the increase in dead space and is accompanied by less density in the occluded lung. BACKGROUND: Acute unilateral pulmonary arterial occlusion causes ventilation-perfusion mismatch of the affected lung area. A diversion of ventilation from nonperfused to perfused lung areas, limiting the increase in dead space, has been described. The hypothesis was that the occlusion of a distal branch of the pulmonary artery would cause local redistribution of ventilation and changes in regional lung densitometry as assessed with quantitative computed tomography. METHODS: In eight healthy, anesthetized pigs (18.5 ± 3.8 kg) ventilated with constant ventilatory settings, respiratory mechanics, arterial blood gases, and quantitative computed tomography scans were recorded at baseline and 30 min after the inflation of the balloon of a pulmonary artery catheter. Regional (left vs. right lung and perfused vs. nonperfused area) quantitative computed tomography was performed. RESULTS: The balloon always occluded a branch of the left pulmonary artery perfusing approximately 30% of lung tissue. Physiologic dead space increased (0.37 ± 0.17 vs. 0.43 ± 0.17, P = 0.005), causing an increase in PaCO2 (39.8 [35.2 to 43.0] vs. 41.8 [37.5 to 47.1] mmHg, P = 0.008) and reduction in pH (7.46 [7.42 to 7.50] vs. 7.42 [7.38 to 7.47], P = 0.008). Respiratory system compliance was reduced (24.4 ± 4.2 vs. 22.8 ± 4.8 ml · cm H2O, P = 0.028), and the reduction was more pronounced in the left hemithorax. Quantitative analysis of the nonperfused lung area revealed a significant reduction in lung density (-436 [-490 to -401] vs. -478 [-543 to -474] Hounsfield units, P = 0.016), due to a reduction in lung tissue (90 ± 23 vs. 81 ± 22 g, P < 0.001) and an increase in air volume (70 ± 22 vs. 82 ± 26 ml, P = 0.022). CONCLUSIONS: Regional pulmonary vascular occlusion is associated with a diversion of ventilation from nonperfused to perfused lung areas. This compensatory mechanism effectively limits ventilation perfusion mismatch. Quantitative computed tomography documented acute changes in lung densitometry after pulmonary vascular occlusion. In particular, the nonperfused lung area showed an increase in air volume and reduction in tissue mass, resulting in a decreased lung density.

Periodontal Healing after Lower Third Molars Extraction: A Clinical Evaluation of Different Flap Designs.

Periodontal healing after third molars extraction seems to be influenced by the choice of different flap techniques. The purpose of the present study was to assess the clinical condition of adjacent first and second molar sites, after the extraction of lower third molars, performed through different flap designs. Eighty patients, aged between 14 and 30 years, were analyzed for periodontal parameters of VPI, PPD, and CAL, pre-operatively (T0), after 15 days (T1), after 1 month (T2), and after 2 months (T3) from extraction. Techniques performed were trapezoidal flap (TRAP), marginal flap (MARG), flap with papilla detachment (DETP), and flap with papilla decapitation (DEC). No significant differences were found between the four flaps at each observation time and considering the interval between T0 and T3, for VPI, PPD at first molar site, PPD at second molar site, and CAL at second molar site. Significant variations for CAL were registered, for each flap, between T0 and T3, in all cases for buccal site, in three cases for buccal-distal site. After 2 months of follow-up, no strong evidence can be assumed for or against the use of a particular flap design for the extraction of lower third molars.

Mediterranean spotted fever and hearing impairment: a rare complication.

Mediterranean spotted fever (MSF) is caused by Rickettsia conorii and transmitted by the brown dog tick Rhipicephalus sanguineus. It is prevalent in southern Europe, Africa and central Asia. The disease usually has a benign course and is characterized by fever, myalgia and a characteristic papular rash with an inoculation eschar ('tache noir') at the site of the tick bite. Severe forms of disease can have cardiac, neurologic or renal involvement. Nervous system complications are unusual and may develop in the early phase of disease or as a delayed complication. Neurological symptoms include headache and alterations of the level of consciousness, and some cases of meningoenchefalitis and Guillain-Barrè syndrome have been also reported. Peripheral nerve involvement is reported only in a limited number of case reports. We describe a case of Rickettsia conorii that was complicated with hearing loss and did not respond to specific treatment. Hearing loss is a rare event, but clinicians should be aware of this complication.