Chronic cough is a common problem in childhood. Sometimes we have
dificulties to harvest the ethiology, specially when we are not alert for
others diagnosis. The authors skipped one of those diseases that are
reemerging in first wolrd countries - whooping cough, pressed for a lack
in mantaining the pertussis vaccination. This disease takes part in
differencial diagnosis in emerging world. So, we all, ped...
Chronic cough is a common problem in childhood. Sometimes we have
dificulties to harvest the ethiology, specially when we are not alert for
others diagnosis. The authors skipped one of those diseases that are
reemerging in first wolrd countries - whooping cough, pressed for a lack
in mantaining the pertussis vaccination. This disease takes part in
differencial diagnosis in emerging world. So, we all, pediatricians and
adults doctors, have to be alert for this possibility.
I was intrigued by Mike Rudolf's editorial on Inpatient Management of
Acute COPD. He states that mortality was highest in small DGH's and
lowest in teaching hospitals. Roberts et al. article, in fact, indicated
that large DGH's had a smaller mortality than even teaching hospitals. I
would not be surprised, as stated, that small DGH's had fewest resources
but certainly working in a large DGH I ha...
I was intrigued by Mike Rudolf's editorial on Inpatient Management of
Acute COPD. He states that mortality was highest in small DGH's and
lowest in teaching hospitals. Roberts et al. article, in fact, indicated
that large DGH's had a smaller mortality than even teaching hospitals. I
would not be surprised, as stated, that small DGH's had fewest resources
but certainly working in a large DGH I have the impression that we have
significantly less resources than teaching hospitals, and yet the largest
DGH's do have marginally better results.
We thank Dr Ng for his comments on the recently published guidelines
on the management of spontaneous pneumothorax.[1] Dr Ng points out that
recurrence rates for pneumothorax after VATS preventative procedures were
lower than those quoted in the guidelines. It should be pointed out that
in the multiple drafts of this document, it was recognised that recurrence
rates after VATs were falling and that f...
We thank Dr Ng for his comments on the recently published guidelines
on the management of spontaneous pneumothorax.[1] Dr Ng points out that
recurrence rates for pneumothorax after VATS preventative procedures were
lower than those quoted in the guidelines. It should be pointed out that
in the multiple drafts of this document, it was recognised that recurrence
rates after VATs were falling and that further improvements in these
figures were likely as operator experience improved. This was recognised
within the guidlines. It is fully expected that as experience and
provision of services impprove, VATS will replace open thoracotomy for
treatment of recurrent pneumothoraces.
In response to Dr Ngs second points regarding surgical treatment of
tension pneumothoraces and hugh bullae, the guidelines obviously could not
take into account every possible clinical scenario. As far as we are aware
there is no evidence to suggest that tension pneumothoraces are more
likely to recur than 'non-tension' spontaneous pneumothoraces. This does
not mean of course that an individual physician should not decide that the
clinical risk in an individual patient either from rupture of a hugh bulla
or recurrence of a tension pneumothorax shouldn't warrent surgical
intervention.
Reference
(1). Henry MT, Arnold A, Harvey J. BTS guidelines for the management
of spontaneous pneumothorax. Thorax 2003; 58: 39ii-52ii.
In their recent paper on atrial septostomy as a treatment for severe
pulmonary arterial hypertension, Reichenberger and colleagues measured
cardiac output before and after this intervention, using both the thermal
dilution and Fick methods. We were puzzled by their choice of the
dilution technique. In these patients atrial septostomy was intended to
produce, and presumably achieved, a right-to-left inte...
In their recent paper on atrial septostomy as a treatment for severe
pulmonary arterial hypertension, Reichenberger and colleagues measured
cardiac output before and after this intervention, using both the thermal
dilution and Fick methods. We were puzzled by their choice of the
dilution technique. In these patients atrial septostomy was intended to
produce, and presumably achieved, a right-to-left interatrial shunt, as
evidenced by the the fall in arterial oxygen saturation following the
procedure. Cardiac output measurement by the thermal dilution method
described in their paper relies upon calculation of the area under the
temperature curve, measured by a thermistor placed in the pulmonary
artery, following an injection of cold saline into the right atrium or
superior vena cava. In simple terms, the greater the area under the curve
(purists would perhaps say “over the curve”, since the injectate produces
a transient fall in blood temperature in the pulmonary artery), the lower
the derived cardiac output. It is not clear why the authors would choose
such a method to estimate cardiac output following atrial septostomy, when
it would be expected that a proportion of the injectate would pass
directly into the left atrium through the interatrial septal defect,
producing an erroneous over-estimate of cardiac output. A reliable method
of measuring blood flow within the pulmonary artery after the procedure
might be expected – at least initially- to show exactly the opposite
result, namely a fall in pulmonary arterial flow caused by the right to
left shunt. We postulate that the explanation for their observed good
correlation between the thermodilution and Fick cardiac outputs is that,
before the procedure, both were reliable methods and that after the
procedure, the true cardiac output increased and was correctly measured by
the indirect Fick method, but was artefactually increased, despite a fall
in pulmonary arterial blood flow, when measured by thermodilution.
We thank Drs Dundas and McKenzie for their comments.[1] We agree
with them that the interrupter resistance (Rint) is able to detect short-
term changes in airway calibre after bronchodilator inhalation. However,
we must disagree on their comment that Rint has a poor long-term
repeatability and their consequent conclusion that Rint is not useful for
routine clinical purposes. The long-term (38 days apart)...
We thank Drs Dundas and McKenzie for their comments.[1] We agree
with them that the interrupter resistance (Rint) is able to detect short-
term changes in airway calibre after bronchodilator inhalation. However,
we must disagree on their comment that Rint has a poor long-term
repeatability and their consequent conclusion that Rint is not useful for
routine clinical purposes. The long-term (38 days apart) Rint
repeatability (2 SD calculated from the analysis of variance results) that
Beelen et al.[2] found in 25 healthy preschool children was actually 0.26
kPa/l.s under field conditions and 0.20 kPa/l.s under laboratory
conditions. These values are very similar to the long-term (3 weeks apart)
repeatability (2 SD of the difference between two sets of measurements)
that Chan et al.[3] found in 72 healthy preschool children (0.23 kPa/l.s)
and the long-term (2.5 months apart) repeatability (2 SD of the difference
between two sets of measurements) that we found in children with a history
of wheezing or cough (0.21 kPa/l.s).[4] In our study, the potential
effects of the disease or treatment on long-term Rint variability were
carefully avoided and only clinically stable children with no change in
treatment were recruited. Assessment of the long-term variability of a
lung function test must be undertaken under circumstances in which the
true lung function can reasonably be expected not to have changed. This is
unlikely to be the case in children with asthma, where lung function is
expected to vary with time. The fact that Chan et al.[3] found a much
higher long-term Rint variability in 95 children with doctor observed
wheeze in the previous 4-6 weeks and on no long-term treatment should not
induce one to conclude that Rint is not useful in clinical practice, but
is, on the contrary, a piece of evidence that Rint is able to detect long-
term changes in airway calibre in children with a recent history of
respiratory symptoms. If we add that Rint is also feasible in preschool
children,[2-4] we can conclude that Rint is a potentially useful tool in
routine clinical practice.
References
(1) Dundas I, McKenzie SA. Is the measurement of lung function using the interrupter technique useful for the clinician? [electronic response to Sly and Lombardi; Measurement of lung function in preschool children using the interrupter technique] thoraxjnl.com 2003http://thorax.bmjjournals.com/cgi/eletters/58/9/742#93
(2) Beleen RMJ, Smit HA, van Strien RT, et al. Short and long term
variability of the interrupter technique under field and standardised
conditions in 3-6 year old children. Thorax 2003;58:1-4.
(3) Chan EY, Bridge PD, Dundas I, et al. Repeatability of airway resistance
measurements made using the interrupter technique. Thorax 2003 ;58 :344-7.
(4) Lombardi E, Sly PD, Concutelli G, et al. Reference values of
interrupter respiratory resistance in healthy preschool white children.
Thorax 2001;56:691-5.
Sly and Lombardi [1] in their recent editorial suggest that
interrupter resistance (Rint) measurements are useful in the management of
lung disease in young children. We believe this claim needs further
consideration.
Rint measurements can be helpful when change following an
intervention, such as the administration of bronchodilator, is greater
than its within-occasion repeatability but for a m...
Sly and Lombardi [1] in their recent editorial suggest that
interrupter resistance (Rint) measurements are useful in the management of
lung disease in young children. We believe this claim needs further
consideration.
Rint measurements can be helpful when change following an
intervention, such as the administration of bronchodilator, is greater
than its within-occasion repeatability but for a measurement to be useful
for following change with time in the individual it must have acceptable
between-occasion repeatability. In the same journal, Beelen et al.[2] have
reported between-occasion variability of 0.38 kPa.L-1.s (2 SD of the
differences between measurements) in 25 healthy children. This figure is
similar to that of Chan et al.[3] who reported 72 measurements in healthy
children and 95 measurements in stable mildly asthmatic children . For the
healthy children, the between-occasion repeatability was 32% expected for
age but for the asthmatics this rose to 52%. As a hallmark of asthma is
bronchial lability, this is not unexpected. These figures need to be
compared to the change expected with treatment. Pao et al.[4] showed that
in an identical group of asthmatic children a change in mean Rint of 16%
was demonstrated with ICS treatment. Although this change was confidently
demonstrated in a group of children it would not be confidently picked up
in the individual because the between-occasion repeatability of Rint is
much greater than the change expected.
Rint seems to be a good tool for research and for that reason
measurements should be standardized. However, we believe its usefulness
for the practicing clinician is quite limited as measurements in the
individual are not sufficiently reliable on a day to day basis. It is
difficult to imagine that further refinement and standardization of the
method will improve this.
References
(1) Sly PD and Lombardi E. Measurement of lung function in
preschool children using the interrupter technique. Thorax 2003;58(9):742-4.
(2) Beelen RM, Smit HA, Van Striene et al. Short and long
term variability of the interrupter technique under field and standardised
conditions in 3-6 year old children. Thorax 2003;58(9):761-4.
(3) Chan EY, Bridge PD, Dundas, I et al. Repeatability of
airway resistance measurements made using the interrupter technique.
Thorax 2003;58(4):344-7.
(4) Pao CS and McKenzie SA. Randomized controlled trial of
fluticasone in preschool children with intermittent wheeze.
Am J Respir Crit Care Med 2002;166(7):945-9.
I am grateful for Dr Henry's reply and further comments on 4
September, 2003.[1] Dr Henry stated that the use of '2 cm' correlating to
'50%' as an indication for chest tube drainage in secondary spontaneous
pneumothorax was supported by evidence, and that this had become a clear
and unambiguous guideline. However, the evidence cited [2] was a 'consensus statement' by the American College of Chest Physici...
I am grateful for Dr Henry's reply and further comments on 4
September, 2003.[1] Dr Henry stated that the use of '2 cm' correlating to
'50%' as an indication for chest tube drainage in secondary spontaneous
pneumothorax was supported by evidence, and that this had become a clear
and unambiguous guideline. However, the evidence cited [2] was a 'consensus statement' by the American College of Chest Physicians,
that large pneumothoraces should be treated with chest tube drainage.
(There is no mention of the figure of 50% in that statement).
Furthermore,
in the same consensus, we do note areas of inconsistency with the British
guidelines. 1. A distinctly different
method of size estimation (as Dr Henry correctly pointed out) 2. The use of chest tube drainage not
only for large secondary spontaneous pneumothoraces, but also for large
primary spontaneous pneumothoraces.
(2) Baumann MH, Strange C, Heffner JE, et al. Management of spontaneous
pneumothorax. An American College of Chest Physicians Delphi Consensus
Statement. Chest 2001;119: 590-602.
This study describes the use of oxygen supplementation before
exercise and during the recovery period in patients with severe COPD, who
were hypoxic at rest and showed exertional desaturation.
The conclusion of this study does not accurately reflect the findings in
relation to the use of oxygen in the recovery period and we would be
concerned that patients with such severe disease and exercise limitatio...
This study describes the use of oxygen supplementation before
exercise and during the recovery period in patients with severe COPD, who
were hypoxic at rest and showed exertional desaturation.
The conclusion of this study does not accurately reflect the findings in
relation to the use of oxygen in the recovery period and we would be
concerned that patients with such severe disease and exercise limitation
would be denied oxygen on the basis of this study.
It cannot be concluded that ‘this group of patients derived no
physiological or symptomatic benefit from oxygen breathed for short
periods before or after submaximal exercise. Oxygen was delivered by a
fixed concentration mask at 28% with a flow rate of 4/lmin. The rationale
for this dose was based on the concentration and flow rate available from
domiciliary systems. The results may have been different if higher flows
and/or concentrations were used. Oxygen is prescribed to increase alveolar
oxygen tension and decrease the work of breathing necessary to maintain a
given oxygen tension.[1] The fixed concentration mask delivers oxygen at
specific concentrations provided that the total gas flow delivered by the
mask is equal to or greater than the peak inspiratory flow of the
patient. Failure to meet this flow rate results in decreased oxygen
tension and an increase in the work of breathing.[2] It is well reported
that inspiratory flow rates rise during exercise and oxygen flow rates
should be adjusted accordingly. In this study there were no objective
measures of ventilation to enable the reader to interpret the results of
the perception of breathlessness.
This group of patients had severe COPD, showed considerable exertional
desaturation and were exercise limited. One might argue that these
patients required oxygen throughout exercise and the oxygen delivered in
recovery although significant in terms of SaO2 was not significant to
relieve the work of breathing and hence perceived breathlessness.
It should be noted that lightweight cylinders which deliver flow rates up
to 15 l/min are now available on prescription. Perhaps the conclusion of
the study should read ‘the practice of prescribing 28% oxygen at 4 litres
to relieve dyspnoea following exercise is inappropriate without careful
assessment. The resources for this would be met by the current expenditure
on inappropriate prescribing.
References
(1) British National Formulary 2003;45:160
(2) Hill SL, Barnes PK, Hollway T, Tennant R. Fixed performance oxygen
masks: an evaluation. BMJ 1984;288:1261-3
I must congratulate the authors for such lucid presentation of a
difficult clinical entity which we all face in day to day practice. I wish
to submit one comment regarding sputum examination in such cases; patients
should not be asked to cough and expectorate until their acute bleeding
stops.
You should wait a day or two, otherwise they may dislodge the formed clot and bleeding will continue.
I must congratulate the authors for such lucid presentation of a
difficult clinical entity which we all face in day to day practice. I wish
to submit one comment regarding sputum examination in such cases; patients
should not be asked to cough and expectorate until their acute bleeding
stops.
You should wait a day or two, otherwise they may dislodge the formed clot and bleeding will continue.
Dr Latour-Perez's concerns[1] are anticipated on page 474 of our
article, which summarises the results of three good quality studies using
CTPA (not multi-slice) as the only imaging modality (references 187-189).
Just after going to press we became aware of a recent excellent large
multicentre study [2] with similar results. Combining these four of
similar design (well conducted, CTPA only, no anticoagul...
Dr Latour-Perez's concerns[1] are anticipated on page 474 of our
article, which summarises the results of three good quality studies using
CTPA (not multi-slice) as the only imaging modality (references 187-189).
Just after going to press we became aware of a recent excellent large
multicentre study [2] with similar results. Combining these four of
similar design (well conducted, CTPA only, no anticoagulation if PE
excluded), the PE rate at 3 months is only 0.9% (10/1100). So, even though
CTPA will miss some small PEs (also true of conventional pulmonary
angiography) this possibility needn't worry clinicians.
References
(1) Latour-Perez J. Anticoagulation in suspected pulmonary embolism and negative Computed Computed tomographic pulmonary [electonic response to BTS Guidelines: British Thoracic Society guidelines for the management of suspected acute pulmonary embolism] thoraxjnl.com 2003 http://thorax.bmjjournals.com/cgi/eletters/58/6/470#87
(2) Van Strijen MJ, et al. Single-detector helical computed
tomography as the primary diagnostic test in suspected pulmonary embolism:
a multicenter clinical management study of 510 patients. Ann Intern Med 2003;138:307-314.
Dear Editor
Chronic cough is a common problem in childhood. Sometimes we have dificulties to harvest the ethiology, specially when we are not alert for others diagnosis. The authors skipped one of those diseases that are reemerging in first wolrd countries - whooping cough, pressed for a lack in mantaining the pertussis vaccination. This disease takes part in differencial diagnosis in emerging world. So, we all, ped...
Dear Editor
I was intrigued by Mike Rudolf's editorial on Inpatient Management of Acute COPD. He states that mortality was highest in small DGH's and lowest in teaching hospitals. Roberts et al. article, in fact, indicated that large DGH's had a smaller mortality than even teaching hospitals. I would not be surprised, as stated, that small DGH's had fewest resources but certainly working in a large DGH I ha...
Dear Editor
We thank Dr Ng for his comments on the recently published guidelines on the management of spontaneous pneumothorax.[1] Dr Ng points out that recurrence rates for pneumothorax after VATS preventative procedures were lower than those quoted in the guidelines. It should be pointed out that in the multiple drafts of this document, it was recognised that recurrence rates after VATs were falling and that f...
Dear Editor
In their recent paper on atrial septostomy as a treatment for severe pulmonary arterial hypertension, Reichenberger and colleagues measured cardiac output before and after this intervention, using both the thermal dilution and Fick methods. We were puzzled by their choice of the dilution technique. In these patients atrial septostomy was intended to produce, and presumably achieved, a right-to-left inte...
Dear Editor
We thank Drs Dundas and McKenzie for their comments.[1] We agree with them that the interrupter resistance (Rint) is able to detect short- term changes in airway calibre after bronchodilator inhalation. However, we must disagree on their comment that Rint has a poor long-term repeatability and their consequent conclusion that Rint is not useful for routine clinical purposes. The long-term (38 days apart)...
Dear Editor
Sly and Lombardi [1] in their recent editorial suggest that interrupter resistance (Rint) measurements are useful in the management of lung disease in young children. We believe this claim needs further consideration.
Rint measurements can be helpful when change following an intervention, such as the administration of bronchodilator, is greater than its within-occasion repeatability but for a m...
Dear Editor
I am grateful for Dr Henry's reply and further comments on 4 September, 2003.[1] Dr Henry stated that the use of '2 cm' correlating to '50%' as an indication for chest tube drainage in secondary spontaneous pneumothorax was supported by evidence, and that this had become a clear and unambiguous guideline. However, the evidence cited [2] was a 'consensus statement' by the American College of Chest Physici...
Dear Editor
This study describes the use of oxygen supplementation before exercise and during the recovery period in patients with severe COPD, who were hypoxic at rest and showed exertional desaturation. The conclusion of this study does not accurately reflect the findings in relation to the use of oxygen in the recovery period and we would be concerned that patients with such severe disease and exercise limitatio...
Dear Editor
I must congratulate the authors for such lucid presentation of a difficult clinical entity which we all face in day to day practice. I wish to submit one comment regarding sputum examination in such cases; patients should not be asked to cough and expectorate until their acute bleeding stops. You should wait a day or two, otherwise they may dislodge the formed clot and bleeding will continue.
...Dear Editor
Dr Latour-Perez's concerns[1] are anticipated on page 474 of our article, which summarises the results of three good quality studies using CTPA (not multi-slice) as the only imaging modality (references 187-189). Just after going to press we became aware of a recent excellent large multicentre study [2] with similar results. Combining these four of similar design (well conducted, CTPA only, no anticoagul...
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