such as "Introduction", "Conclusion"..etc
Intravasation of adipose tissue or bone marrow can lead to acute
blockage of pulmonary microcirculation, with increased resistance in
the arterial pulmonary capillaries and a secondary increase of pressure
in the pulmonary artery and the right atrium . This causes the pCO2 to
rise and oxygen saturation to decrease, with tachycardia resulting from
left ventricular volume deficiency. To date, no comparable trials on
large animals have been done examining cryoablation in bone tissue with
modern cryoprobes. Kerschbaumer et al. 
found no lung embolisms in rabbits after cryosurgery. On the other
hand, Oeseburg also used rabbits and observed a large number of bone
marrow embolisms in the extraosseous veins immediately after
One of the aims of this study was the detection of larger,
clinically significant lung embolisms, we restricted ourselves to
venously measurable hemodynamic parameters so as not to cause
additional, iatrogenic complications. Likewise, we decided against a
transesophageal ultrasound probe for detecting microemboli [24,25]
since the animals already were administered a large transesophageal
tube to aspirate gastric juices during the operation, thus leaving no
room for an ultrasound probe.
None of the animals showed histological evidence of lung embolisms,
nor were any embolism-specific hemodynamic phenomena or blood gas
changes observed. The rise in pCO2 seen in all animals at
the end of the operation is likely to be due to the impaired pulmonary
gas exchange and decreased venous flow resulting from the increased
intraabdominal pressure, which in turn can probably be attributed to
the distended rumen during while the animals were lying on their right
side. The rise in pCO2 explains the slight acidosis which
the animals showed towards the end of the operation, and is therefore
not to be seen as pathological.
In our opinion, the absence of significant embolisms is due to the
small diameter of the probe, which prevents the intramedullar pressure
from rising when the probe is introduced. A further reason could be the
controlled expansion of the ice front in the bone, which prevents
intramedullar pressure from peaking, and hence bone marrow or adipose
tissue from being pressed out of the marrow cavity.
As expected, we did not observe any decrease in body temperature
after cryosurgery as was reported for small animals such as mice and
The minimal reduction in body temperature which we did see towards the
end of the operation can be explained by the normal cooling of the body
despite a heating pad. We believe that the more pronounced decrease in
body temperature in small animals is due to their smaller body volume,
next to which the cryoprobe is comparatively much larger. Hence, the
results of our trials with large animals can be extrapolated more
readily to human patients than can results from similar trials with
small animals, and a significant decrease in body temperature is not to
be expected in human patients.
Except for hemoglobin, all blood chemistry values remained
essentially unchanged during the operation. The drop in hemoglobin by
on the average 0.5 g/dl is not clinically significant.
Clinical follow-up revealed one serious wound infection, which underscores the tendency these wounds have for infection .
Even so, it would seem to us that the risk of infection can be
controlled with perioperative administration of antibiotics, as is also
evident from the histology of the treated bone sections, none of which
developed acute inflammation. Nevertheless, it must be admitted that
the tissue treated here was healthy bone in animals with an intact
immune system, and a higher infection rate must be expected when
applying this method to patients with advanced malignancy.
Convalescence after cryosurgery is associated with changes in bone
stability, a topic which few studies have addressed so far. Gage et al.
(1967) reported 11 spontaneous fractures in 20 dogs, where the entire
cross-section of the femur was frozen over a length of 4.5–7 cm . Further studies report a maximum reduction in bone stability some 8 weeks after cryosurgery [27,20].
The absence of fractures in our trial shows that limiting bone necrosis
by controlled freezing and minimum tissue loss when introducing the
cryoprobe helps minimise the reduction in bone stability, and hence
prevent fractures. To be sure, the size of a tumour dictates the extent
of the freezing zone, so that stabilising measures may be necessary.
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