We thank Dodd et al. for their letter that reflects the concerns of many clinicians that short burst oxygen must be beneficial to patients if only we could prove it. Unfortunately the evidence collected to date for short bust therapy does not support this hope and since our own publication [1] a further very similar study has reached the same conclusion.[2]
We thank Dodd et al. for their letter that reflects the concerns of many clinicians that short burst oxygen must be beneficial to patients if only we could prove it. Unfortunately the evidence collected to date for short bust therapy does not support this hope and since our own publication [1] a further very similar study has reached the same conclusion.[2]
In answer to the specific points raised in this letter we reassert that the conclusion of the study accurately reflects the results in which it is stated that "we found no increase in mean walk distance after oxygen and no improvement in mean breathlessness scores or recovery times with oxygen taken either before or after exercise" (abstract) and "Oxygen during recovery. The two walks performed by each subject in this study were comparable; there was no significant difference between the mean distances walked degree of breathlessness or arterial oxygen saturation at the end of the walks" (results). In the discussion we state:
"The outcomes of both parts of this study are clear. At rates available from domiciliary systems in the UK, neither pre-breathing oxygen before exercise nor breathing oxygen during recovery was effective in relieving dyspnoea or usefully increasing submaximal exercise tolerance in COPD patients with exercise limitation and desaturation on air". We conclude;
"In summary. Our studies do not support a useful therapeutic role for domiciliary oxygen by cylinder in COPD patients who desaturate on exercise, whether it is used before or after exercise. We suggest that current prescribing practice for this therapy in the UK be revised. If the evidence from this and previous studies is to be followed, only patients with a demonstrable objective benefit should be considered suitable for such therapy".
The argument that 28% oxygen with a flow rate of 4 litres per minute may have reduced alveolar oxygen tensions and hence increased the work of breathing is negated by the increased arterial oxygen saturations observed in the subjects who were administered oxygen. We agree that the conclusion of this study is ’the practice of prescribing 28% oxygen at 4 litres to relieve dyspnoea following exercise is inappropriate without careful assessment’ and state in our own conclusions ‘domiciliary oxygen should in future only be prescribed for such patients if they have shown objective evidence of benefit on exercise testing’. The suggestion that such patients would benefit from higher flow rates delivered from new lightweight cylinders now appearing in the UK market is an interesting one but at present is just speculation and we could not deduce such a conclusion from the results of our study. We are sure that further research in this area will be conducted.
References
(1) Nandi K, Smith AA, Crawford A et al. Thorax 2003;58:670-3.
(2) Lewis CA, Eaton TE, Young P, Kolbe J. Eur Respir J 2003;2:584-8.
The paper of Beddow et l. deal with important topics such as acute
respiratory failure following lung resection.
Postoperative mortality and
morbidity after lung resection are decreasing but remain significant. When
treated with invasive endotracheal mechanical ventilation (ETMV), acute
respiratory insufficiency after lung resection is fatal in up to 80% of
cases. In a prospective observat...
The paper of Beddow et l. deal with important topics such as acute
respiratory failure following lung resection.
Postoperative mortality and
morbidity after lung resection are decreasing but remain significant. When
treated with invasive endotracheal mechanical ventilation (ETMV), acute
respiratory insufficiency after lung resection is fatal in up to 80% of
cases. In a prospective observational study conducted after bilateral lung
transplantation, NIV was found to avoid reintubation. Furthermore
oxygenation and respiratory acidosis were improved, with a low rate of
complications and no mortality in the intensive care unit (ICU).[1] A
prospective randomized controlled study, in the ICU setting, demonstrated
that NIV was safe and effective in reducing the need for reintubation and
improving in-hospital and 3-month survival in 24 patients with hypoxemic
ARF after lung resection compared with standard medical treatment.[2]
These findings suggest that NIV may replace conventional mechanical
ventilation in some circumstances. In the paper of Beddow, the use of NIV
should have been discussed. Was mini-trachesostomy the treatment of choice
in hypoxemic respiratory failure following lung resection? Litterature
is convincing today and suggests that NPPV should be added to the
standard conservative therapy of AHRF complicating lung resection.
Finally, we agree with the authors "although not the most frequent
postoperative complication in this patient population, lung injury
produces the highest all cause mortality". In this setting Non Invasive
ventilation could reach the goal : to avoid endotracheal intubation
References
(1) Rocco M, Conti G, Antonelli M, et al. Noninvasive pressure support
ventilation in patients with acute respiratory failure after bilateral
lung transplantation. Intensive Care Med. 2001;27:1622-1626.
(2) Auriant I, Jallot A, Hervé P, et al. Noninvasive ventilation reduces
mortality in acute respiratory failure following lung resection. Am J
Respir Crit Care Med. 2001;164:1231-1235.
We thank Dr Chan for his further reponse 'error in citation' to the
recently published BTS guidelines for the management of spontaneous
pneumothorax.[1]
Dr Chan has pointed out that our statement in a previous correspondence to
him, that a 2cms rim of pneumothorax was a clear indication for use of an
intercostal chest drain, was supported by the recent ACCP Delphi consensus
document [2] is a error in...
We thank Dr Chan for his further reponse 'error in citation' to the
recently published BTS guidelines for the management of spontaneous
pneumothorax.[1]
Dr Chan has pointed out that our statement in a previous correspondence to
him, that a 2cms rim of pneumothorax was a clear indication for use of an
intercostal chest drain, was supported by the recent ACCP Delphi consensus
document [2] is a error in citation is technically correct. The evidence
for this statement is supported in the BTS document by a references also
qouted in our previous reply to him later in that paragraph and again
below. We recommended the use of the '2 cm rule' in secondary spontaneous
pneumothoraces only and not in primary pneumothoraces. As pointed out in
the previous correspondence 2 cm will usually (but not always) correspond
to a pneumothorax of >50% and these tend not to respond to simple
aspiration in patients with secondary pneumothoraces. The same evidence is
not available for primary pneumothoraces. As Dr Chan will be aware the two
sets of guidlelines quoted were arrived at by totally different means. The
delphi document was arrived at by consensus of many specialists, whereas
the BTS guidelines were arrived at by review of the published evidence and
in the absence of evidence on which to base recommendations, a consensus
of the BTS standards of care committee made recommendations. It is not
therefore surprising that there are differences between the various sets
of guidelines.
References
(1) Henry MT, Arnold T, Harvey J. BTS guidelines for the management of
spontaneous pneumothorax. Thorax 2003; 58: 39ii-52ii.
(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.
(3) Archer GJ, Hamilton AAD, Upadhyag R, et al. Results of simple
aspiration of pneumothoraces. Br J Dis Chest 1985; 79: 177-182. III
We are grateful to Dr Kelly for highlighting the important finding of
hypochloraemic metabolic alkalosis in patients with acute exacerbation's of
cystic fibrosis.[1,2] It is important to consider the need to correct this
abnormality in a timely and appropriate way, by avoiding potential added
metabolic acidosis on an established respiratory acidosis in sick patients
with severe CF lung disease. The role fo...
We are grateful to Dr Kelly for highlighting the important finding of
hypochloraemic metabolic alkalosis in patients with acute exacerbation's of
cystic fibrosis.[1,2] It is important to consider the need to correct this
abnormality in a timely and appropriate way, by avoiding potential added
metabolic acidosis on an established respiratory acidosis in sick patients
with severe CF lung disease. The role for correction with volume and
electrolyte replacement in reducing hyperventilation and hypercapnia is at
present unknown, and must be tested to avoid fatigue and spiraling
respiratory failure.
Our recommendation at present is to ascertain the severity of respiratory
failure with arterial blood gas analysis, establish venous access and
replace salt/fluid deficits over 24 to 48 hours, in concert with usual
treatments to restore CO2 equilibrium at a satisfactory level.
References
(1) Kelly SJ. Lung Alert. Salt depletion and hypoalbuminaemia in cystic
fibrosis may add to hypercapnia in acute respiratory failure. Thorax
2003;58:973.
(2) Holland AE, Wilson JW, Kotsimbos TC, Naughton MT. Metabolic alkalosis
contributes to acute hypercapnic respiratory failure in adult cystic
fibrosis. Chest 2003;124:490-493.
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.
Dear Editor
We thank Dodd et al. for their letter that reflects the concerns of many clinicians that short burst oxygen must be beneficial to patients if only we could prove it. Unfortunately the evidence collected to date for short bust therapy does not support this hope and since our own publication [1] a further very similar study has reached the same conclusion.[2]
In answer to the specific points ra...
Dear Editor
The paper of Beddow et l. deal with important topics such as acute respiratory failure following lung resection.
Postoperative mortality and morbidity after lung resection are decreasing but remain significant. When treated with invasive endotracheal mechanical ventilation (ETMV), acute respiratory insufficiency after lung resection is fatal in up to 80% of cases. In a prospective observat...
Dear Editor
We thank Dr Chan for his further reponse 'error in citation' to the recently published BTS guidelines for the management of spontaneous pneumothorax.[1] Dr Chan has pointed out that our statement in a previous correspondence to him, that a 2cms rim of pneumothorax was a clear indication for use of an intercostal chest drain, was supported by the recent ACCP Delphi consensus document [2] is a error in...
Dear Editor
We are grateful to Dr Kelly for highlighting the important finding of hypochloraemic metabolic alkalosis in patients with acute exacerbation's of cystic fibrosis.[1,2] It is important to consider the need to correct this abnormality in a timely and appropriate way, by avoiding potential added metabolic acidosis on an established respiratory acidosis in sick patients with severe CF lung disease. The role fo...
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...
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