Needle thoracocentesis in tension pneumothorax: insufficient cannula length and potential failure

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Letters to the Editor

basicervicalfracture with a dynamic hip screw.The authors suggestthat the collapseof the femoral neck allowed the greater trochanter to impinge and lever on the acetabular lip, causing the dislocation. But the collapseof the femoral neck is a common complication of fractures treated by screw/platedevices. In these two reports as in the casereported by Munjal and Krikler,’ no evidence was found of infection although we know that infection can be a factor in dislocation after internal fixation of trochanteric fractures’. A. Combalia

The trocar inside a Venflon is hollow to allow the flashback of blood to be seen once a vein is cannulated. In a brown (14g) Venflon this trocar is considerablylonger than the cannula which usually overlies it (7 cm versus 4.5 cm). The trocar would have breached the chest wall in all patients in this study. The introduction of the trocar alone alsohas the advantage that it will not kink whilst in situ and therefore may be a safertemporizing measurebefore chest tube placement. In casesof failed needle thoracocentesiswith a cannula I would recommend the ‘trocar alone’ method as it takes little extra time to perform (the equipment is, literally, to hand) and may prove lifesaving. G. T. R. Pattison

References Munjal S and Krikler SJ.Dislocation of the hip following intertrochanteric fracture. Injury 1995;26: 645. Iwegbu CG. Dislocation of the hip following Ender nailing. A casereport. I BoneJoint Surg [Am] 1981; 63A: 839.

Reece AT, Oni OOA and Chan RNW. Nontraumatic dislocation of the hip following screw/plate fixation for a femoral neck fracture. I Orthop Truuma 1990;4: 96. Evans PEL. Septic dislocation of the hip after internal fixation of trochanteric fractures. Injury 1982;13: 185. Author’s reply We are grateful to Dr Combaliafor his interest in our case report and his helpful comments. Our literature search failed to identify either of the two caseshe mentions. The circumstancesof our casewere different from both of the two previous reports cited. The initial insertion of the dynamic hip screw appearedto proceed without difficulty or complication, and there was no significant collapse of the femoral neck prior to the dislocation. Following initial surgery the wound appeared to heal well with no erythema or any other signsof infection, and the patient’s temperature remained normal. When the hip was reopened following dislocation, again there were no clinical signsof infection. We therefore still have no alternative explanation to offer for the dislocation other than that proposedin our casereport. S. J. Krikler

Reference 1 Britten S, Palmer SH and Snow TM. Needle thoracocentesisin tension pneumothorax: insufficient cannula length and potential failure. Injury 1996; 27: 321. Incidence of five common fracture types in an institutional epileptic population Desaiet al.’ have produced a significant contribution to the literature on this subject, more than trebling the patient years reported in the studiesto which they refer. Their results clearly show that the population in their study is at a greatly increased risk from four of the five fractures, although they do not appear to have assessed the statisticalsignificanceof their data. In their discussion,they mention several possiblefactors which might contribute to this increasedincidence. As the population in their study was resident in an institution, their subjectsrepresent a highly selectedsub-population of epileptic patients. In therefore seems unlikely that the expected numbers of fractures in populations of a similar age give a valid estimate of the study population risk of fracture. It would be helpful if data were given on the other possible influences, such as head injury, mental retardation, cerebral palsy, or myopathy or neuropathy. Whilst their data support the conclusion that institutionalized patients are at increasedrisk of fracture, it does not seemjustified to attribute this implicitly to their epilepsy. S. J. Krikler

Needle thoracocentesis in tension pneumothorax: insufficient cannula length and potential failure Mr Britten and his colleagues’ highlight an important problem in difficult casesof tension pneumothorax, i.e. the initial failure of needle decompression.I have had the unfortunate experience of this happening to a patient of mine. A normally thin, 36-year-old woman presentedwith a simple pneumothorax treated with closed chest tube drainage. Unfortunately, the tube became displaced and widespread surgical emphysemaof the upper thorax and neck occurred along with a left-sided tension pneumothorax. Decompressionwith a 1Pgauge cannula (brown Venflon) was not successfuldue to the thickness of the chest wall, abnormally expanded by the surgical emphysema. Firm manual pressure over the area reduced the emphysemaand I was able to introduce the trocar from the cannula, thus successfully decompressing the tension pneumothorax.

Reference 1 Desai KB, RibbansWJ and Taylor GJ. Incidence of five common fracture types in an institutional epileptic population. Injury 1996;27: 97. Author’s reply I would like to thank Mr Krikler for his kind words about our paper on fracture types in an epileptic population. We were aware of the potential false selectionof this group of patients, hence we were careful to entitle our paper ‘An institutional epileptic population’. However, the Centre from which the patients were studied is an extremely active unit. It lies within a large area of land which is actively managedby the staff and residents.This includes