Bone cement embolism attached to central venous catheter.

We report on a rare complication of poly(methyl methacrylate) (PMMA), injected into the spine, which then inadvertently leaked into the venous system. This resulted in an embolism of PMMA and produced a mass surrounding a triple lumen central venous catheter located in the superior vena cava. The catheter as well as the attached mass of PMMA was retrieved safely by cardiothoracic surgery. This case emphasizes the importance of prompt diagnosis and treatment and illustrates the need for close monitoring of patients undergoing any spinal surgery that includes vertebroplasty.

Effect of mild hypothermia on cerebral oxygen uptake during gradual cerebral perfusion pressure decrease in piglets.

OBJECTIVE: To study the effect of mild hypothermia on cerebral oxygen metabolism and brain function in piglets during reduced cerebral blood flow because of gradual reduction of the effective cerebral perfusion pressure (CPP). DESIGN: Comparison of two randomized treatment groups: normothermic group (NT; n = 7) and hypothermic group (HT; n = 7). SETTING: Work was conducted in the research laboratory of the Institute for Pathophysiology, Friedrich Schiller University, Jena, Germany. SUBJECTS: Fourteen piglets (14 days old) of mixed German domestic breed. INTERVENTION: Animals were anesthetized and mechanically ventilated. An epidural balloon was gradually inflated to increase intracranial pressure to 25 mm Hg, 35 mm Hg, and 45 mm Hg every 30 mins at adjusted mean arterial blood pressures. After determination of baseline CPP (NT, 79+/-14 mm Hg; HT, 84+/-9 mm Hg), CPP was reduced to approximately 70%, 50%, and 30% of baseline (NT, 38.1+/-0.5 degrees C; HT, 31.7+/-0.5 degrees C). MEASUREMENTS AND MAIN RESULTS: Every 25 mins after the gradual CPP reductions. Mild hypothermia induced a reduction of the cerebral metabolic rate of oxygen (CMRO2) to 50%+/-15% of baseline values (baseline values, 352+/-99 micromol x 100 g(-1) x min(-1)) (p < .05). Moreover, the electrocorticogram was altered to a pattern of reduced delta activity (p < .05) but unchanged higher frequency activity. The cerebral oxygen balance in HT animals remained improved until CPP reduction to 50%, indicated by a reduced cerebral arteriovenous difference of oxygen but elevated brain tissue Po2 (p < .05). Further CPP reduction gave rise to a strong CMRO2 reduction (NT, 19+/-21%; HT, 15+/-15%; p < .05). However, the high-frequency band of electrocorticogram was less reduced in hypothermic animals (p < .05). CONCLUSIONS: Mild whole body hypothermia improves cerebral oxygen balance by reduction of brain energy demand in juvenile piglets. The improvement of brain oxygen availability continues during a mild to moderate CPP decrease. A loss of the difference in CMRO2 between the hypothermic and normothermic piglets together with the fact that brain electrical activity was less suppressed under hypothermia during severe cerebral blood flow reduction indicates that hypothermic protection may involve some other mechanisms than reduction of brain oxidative metabolism.

A piglet model for evaluation of cerebral blood flow and brain oxidative metabolism during gradual cerebral perfusion pressure decrease.

A piglet model was developed to study the effect of epidural volume expansion on cerebral perfusion pressure (CPP) by stepwise elevating intracranial pressure (ICP). Mean arterial blood pressure (ABP) was strictly maintained using an extracorporeal ABP controller. Two-week-old piglets (n = 10) were studied by surgically placing an epidural balloon over the right parietal region and gradually increasing the inflation to increase ICP to 25, 35 and 45 mm Hg, maintaining each pressure level for 30 min. Regional cerebral blood flow was measured using the colored microsphere technique, and cerebral oxygen delivery and cerebral metabolic rate of oxygen were calculated at baseline conditions and after reaching ICP levels of 25, 35 and 45 mm Hg. The results showed that this model of epidural volume expansion reproducibly reduces CPP to 70, 50 and 33% of baseline CPP values with elevation of ICP, and that the physiological variables remained stable throughout each increase in ICP. We conclude that the model simulates the effects of an acute intracranial focal mass expansion and is well suited for the evaluation of different therapeutical strategies for increased ICP in newborns and infants.

Hypothermia related changes in electrocortical activity at stepwise increase of intracranial pressure in piglets.

Recent experimental studies have demonstrated that mild hypothermia can be effective in the control of intracranial hypertension. However, investigations to analyze the effects of hypothermia on changes in brain oxygen metabolism and electrocortical activity caused by increased intracranial pressure (ICP) are lacking. We examined the effects of mild hypothermia on electrocorticogram (ECoG) in combination with measurement of regional cerebral blood flow (CBF) and estimation of brain oxygen metabolism during stepwise increase of ICP. For this purpose thirteen female piglets (14 days old, 4-5 kg b.w.) were anaesthetized and mechanically ventilated. An epidural balloon was gradually inflated in order to increase ICP to 25 mmHg, 35 mmHg and 45 mmHg every 30 minutes at adjusted mean arterial blood pressures (MAP). This procedure resulted in gradual cerebral perfusion pressure (CPP) reduction of about 70%, 50%, and 30% of baseline [baseline CPP: normothermia (NT) 80+/-3 mmHg; hypothermia (HT) 84+/-3 mmHg]. Control animals were maintained in a normothermic state (38.6+/-0.2 degrees C). HT animals were surface cooled and maintained at 31.9+/-0.1 degrees C. ECoG, regional CBF, cerebral oxygen delivery (cDO2) and the cerebral metabolic rate of oxygen (CMRO2) were estimated during the normothermic period, after hypothermic stabilization, and after the gradual CPP reductions. The baseline ECoG showed the typical delta-dominated frequency pattern for isoflurane anaesthesia. At the hypothermic level, a frequency shift was seen from delta activity towards the higher frequencies (theta- and alpha activity) and the total spectral power was significantly reduced (56+/-17% from baseline, p < 0.05). the cortical CBF decreased markedly to 67+/-10% (p < 0.05), whereas the medulla oblongata blood flow increased slightly. During controlled increase of ICP by regional mass expansion from epidural balloon inflation, we found at mild and moderate stages of ICP increase (25 and 35 mmHg) only minimal changes in the ECoG in hypothermic animals compared to the hypothermic baseline, whereas the ECoG in normothermic animals showed a marked decrease in frequency, amplitude and total spectral power. We conclude that mild hypothermia produces an arousal-like ECoG activity with marked frequency shift to alpha activity and a change from high to low voltage activity. Furthermore, the hypothermic brain showed a preserved neuronal function at moderate stages of ICP. Obviously, hypothermia improves the functional tolerance of the brain to impaired oxygen supply.