Un resbalón diagnóstico: luxación rotuliana traumática no sospechada. Signos directos e indirectos observados por resonancia magnética / A diagnostic pitfall: unsuspected patellar traumatic luxation. MRI direct and indirect signs

Propósito: Nos llamó la atención la frecuencia de luxaciones rotulianas traumáticas (LRT) no sospechadas durante la consulta y el examen físico de pacientes que exploramos por gonalgia o inestabilidad mediante resonancia magnética (RM). Nuestro Objetivo es demostrar los signos de LRT que hallamos en estos pacientes y las estructuras anatómicas que resultan más frecuentemente afectadas. Material y método: Diez y ocho pacientes con LRT fueron explorados mediante RM con cortes axiales, coronales y sagitales ponderados en T1 y T2. Resultados: El 61,1 por ciento de los pacientes no presentaba sospecha de LRT antes del examen y relataba un episodio de esguince o traumatismo como comienzo de los síntomas; el 83,3 por ciento mostró lesión del retináculo interno y el ligamento femoropatelar (LFP). Las contusiones óseas en la cara medial de la rótula estuvieron presentes en el 88,8 por ciento y en el borde lateral del cóndilo femoral externo en el 100 por ciento. El 1,1 por ciento mostró un fragmento óseo patelar desprendido y el 55,5 por ciento mostró lateral del cóndilo femoral externo en el 100 por ciento. El 1,1 por ciento mostró un fragmento óseo patelar desprendido y el 55,5 por ciento mostró lateral del cóndilo femoral externo en el 100 por ciento. El 1,1 por ciento mostró un fragmento óseo patelar desprendido y el 55,5 por ciento mostró condromalacia traumática. Todos presentaron derrame articular. "Patela alta" se comprobó en el 55,5 por ciento de los casos. La rótula subluxada estuvo presente en el 72,2 por ciento. Conclusión: La LRT pasa muchas veces desapercibida en la consulta traumatológica. La RM constituye en un método eficáz para su diagnóstico, siempre y cuando se interpreten correctamente los signos de presentación de esta patología. El diagnóstico correcto de una lesión no sospechada puede provocar un cambio en la terapéutica y el manejo del paciente

Effects of noninvasive positive pressure ventilation on gas exchange and sleep in COPD patients.

STUDY OBJECTIVE: The role of nocturnal noninvasive positive pressure ventilation (NPPV) in the treatment of patients with hypercapnic COPD remains controversial. Beneficial effects reported after prolonged use have included an improvement in gas exchange. The purpose of this study was to examine the short-term effects of NPPV on gas exchange and sleep characteristics in patients with hypercapnic COPD and to determine if similar acute changes in gas exchange are associated with improved sleep quality. DESIGN: Prospective, randomized, controlled trial. SETTING: Sleep laboratory of a university hospital. PATIENTS: Six patients with severe but stable hypercapnic COPD (PaCO2=58+/-4 [SE] mm Hg). Mean age was 63+/-6 (SD) with an FEV1=0.58+/-0.09 L. INTERVENTIONS AND MEASUREMENTS: Patients were studied in the sleep laboratory for a total of three nights. On nights 2 and 3, arterial catheters were placed prior to the study. Following an acquaintance night, patients were randomized to either a control-sham night on 5 cm H2O nasal continuous positive airway pressure (CPAP) or an NPPV night using a ventilatory support system (BiPAP; Respironics Inc; Murrysville, Pa) at previously determined optimal settings. The third night consisted of the opposite for each patient, either a control-sham or an NPPV night. On the second and third nights, three arterial blood gas readings were obtained: (1) baseline wakefulness; (2) non-rapid eye movement (NREM) sleep; and (3) rapid eye movement (REM) sleep. RESULTS: During NREM sleep, NPPV in comparison to the control-sham night on low level CPAP caused no significant change in PaCO2 (60+/-4 to 59+/-3 mm Hg [p=0.6]) and a decrease in PaO2 (96+/-9 to 72+/-5 mm Hg [p=0.04]). During REM sleep, NPPV in comparison to the control-sham night on low level CPAP caused no significant change in either PaCO2 (63+/-7 to 57+/-2 mm Hg [p=0.46]) or PaO2 (67+/-7 to 75+/-8 mm Hg [p=0.51]). Sleep efficiency and total sleep time (TST) increased significantly with NPPV in comparison to the control-sham night on low level CPAP: from 63+/-7% to 81+/-4% (p<0.05) and from 205+/-32 to 262+/-28 min (p<0.05), respectively. Sleep architecture, expressed as a percentage of TST, was unchanged on the NPPV night compared to the control-sham night on low level CPAP. The number of arousals during the night was also unchanged with NPPV in comparison to the control-sham night on low level CPAP (45+/-11 to 42+/-9 [p=not significant]). CONCLUSIONS: NPPV acutely improved sleep efficiency and TST in patients with hypercapnic COPD without significantly improving gas exchange. Other sleep parameters, including sleep architecture and the number of arousals during the night, remained unchanged during NPPV. These data suggest that the beneficial effects of NPPV in patients with hypercapnic respiratory failure are not solely due to an improvement in gas exchange but may be more complex with other factors potentially having contributing roles.

Cheyne-Stokes respiration during sleep in congestive heart failure.

Cheyne-Stokes respiration (CSR) is a form of sleep-disordered breathing seen in approximately 40% of congestive heart failure patients with a left ventricular ejection fraction of < 40%. It is characterized by a crescendo-decrescendo alteration in tidal volume separated by periods of apnea or hypopnea. Sleep is generally disrupted, often with frequent nocturnal arousals. Clinical features include excessive daytime sleepiness, paroxysmal nocturnal dyspnea, insomnia, and snoring. Proposed mechanisms include the following: (1) an increased CNS sensitivity to changes in arterial PCO2 and PO2 (increased central controller gain); (2) a decrease in total body stores of CO2 and O2 with resulting instability in arterial blood gas tensions in response to changes in ventilation (underdamping); and (3) an increased circulatory time. In addition, hyperventilation induced hypocapnia seems to be an important determinant for the development of CSR. Mortality appears to be increased in patients with CSR compared to control subjects with a similar degree of left ventricular dysfunction. Therapeutic options include medically maximizing cardiac function, nocturnal oxygen therapy, and nasal continuous positive airway pressure. The role that other therapeutic modalities, such as inhaled CO2 and acetazolamide, might have in the treatment of CSR associated with congestive heart failure has yet to be determined.