Impact factor of chest journal

TB pleuritis profile pleural fluid

TB pleuritis profile
pleural fluid protein usually>5g/dl
PMN increaseได้แค่ wi 2nd weeks
PPD almost always positive at >8wks of symptoms
Pleural fluid EO>10% or mesothelial cell>5%–>exclude TB
ADA: 70U/L suggestive
most ADA in TB pleura=ADA2 found only in monocyte
sens. 88, spec 85% (if lymphocyte/PMN ratio>0.75–>sens/spec.>90%)
false positive ได้ใน RA, empyema (2อันนี้PMN เด่น), Q fever, brucellosis
, lymphoma, other malignancy
IFN gamma if cut off at>3.7IU/ml sens. 98 spec 98%
สรุปrecommend ADA cost-effective
PCR for TB vary sens. 20-73% spec. 93% แต่contaminateง่ายในบ้านเรา สรุปไม่ต้องส่ง

การแยก RA pleural effusion and Empyema

The combination of a polymorphonuclear exudate along with a low pleural fluid glucose and pH makes the distinction between rheumatoid effusions and empyema difficult. This is particularly true for the tuberculous empyema, because mycobacterial organisms are fastidious to culture and are not often recovered on an acid-fast stain. However, there are several findings that can assist the clinician in making this distinction.

1. the finding of an elevated pleural fluid rheumatoid factor (titers >1:320 or semiquantitative levels >80 IU/mL) is fairly typical, although not specific for this condition.

2. rheumatoid effusions typically have low C4 complement levels (<0.03 g/L), which stand in strong contradistinction to C4 levels in tuberculous and malignant effusions that are 10-fold higher on average [9].

3.pleural fluid cytology will occasionally show a characteristic epithelioid cell similar to cells seen in rheumatoid synovitis [14]. This finding is quite specific when present.

การแยก concomittant infection from Rheumatoid effusion
When a patient is seen with RA and a pleural effusion characterized by a low glucose level (<20 mg/dL), a low pH (1:320
แต่ผู้ป่วยเป็น RA อยู่ก็ขึ้นอยู่แล้ว การปั่นPF + C/S ช่วย exclude superimposed infection กรณี pH &glucose ต่ำมากๆ

Inhale CO2 in OSA

-ใน OSA ไม่เสีย Hypercapnic drive (ต่างกับ COPD)
-คนปกติหายใจ เมื่อ CO2 คั่ง
-ในคนที่ OSA มี ช่วง apnea and hypervent
-พอ Apnea Co2 คั่ง Hypervent –> Co2 ลดต่ำกว่า theshold apnea ใหม่
-เลยให้ CO2 inhale เอาไว้ จะช่วยลด Fluctuation ให้ CO2 เหนือ apnea theshold เอาไว้
-แต่ใช้ได้ในคนที่ Nonhypercapnic OSA เท่านั้น นะ

Co2 Narcosis in COPD

Normal respiration is driven mostly by the levels of carbon dioxide in the arteries, which are detected by central chemoreceptors, and very little by the oxygen levels. An increase in carbon dioxide will cause chemoreceptor reflexes to trigger an increase in respirations. Hypoxic drive accounts normally for 10% of the total drive to breathe. This increases as the PaO2 goes to 70 torr and below, while hypoxic drive is no longer active when PaO2 exceeds 170 torr. The hypoxic drive is so weak that unconsciousness will develop before respiratory distress is noted and is therefore a risk for high altitude flying pilots. For this reason, supplemental oxygen is required by Federal Aviation Regulations[1] for pilots flying above about 12,500 feet altitude in unpressurized airplanes.

In the past, it was believed that in cases where there are chronically high carbon dioxide levels in the blood such as in COPD patients, the body will begin to rely more on the oxygen receptors and less on the carbon dioxide receptors. And that in this case, when there is an increase in oxygen levels the body will decrease the rate of respiration.

Recent studies have proven that COPD patients who have chronically compensated elevated CO2 levels (known as “CO2 Retainers”) are not in fact dependent on hypoxic drive to breathe. However, when in respiratory failure and put on high inspired oxygen, the CO2 in their blood may increase via three mechanisms, namely the Haldane Effect, the Ventilation/Perfusion mismatch (where the regional pulmonary hypoxic vasoconstriction is released) and by the removal or reduction of the hypoxic drive itself.

The respiratory drive is normally largely initiated by PaCO2 but in chronic obstructive pulmonary disease (COPD) hypoxia can be a strong driving force and so if the hypoxia is corrected then the respiratory drive will be reduced. There will also be a loss of physiological hypoxic vasoconstriction which is partly protecting the patient from the effects of areas of gross alveolar hypoventilation

Intraabdominal hypertension

Severity
Mild 12-15
Mod 15-20
Severe 20-25
Very severe >25
compartment > 20

Intra-abdominal hypertension (IAH) is defined as a sustained or repeated pathologic elevation of IAP > 12 mmHg.

Normal IAP is approximately 5-7 mmHg in the critically ill, but varies by disease severity with an IAP of 20-30 mmHg being common in patients with severe sepsis or an acute abdomen

Abdominal compartment syndrome (ACS) is defined as a sustained increase in IAP > 20 mmHg (with or without an APP 25 mmHg.

TREATMENT
Abdominal compartment syndrome resulting from tense ascites
is an indication for immediate paracentesis. Pre- and
postparacentesis measurements of IABP, urine output, hemodynamics, and airway pressures help confirm ACS and
demonstrate the benefit of therapeutic intervention. In most
other cases of ACS, prompt surgical decompression is indicated.
Determining the appropriate timing for surgical intervention
is challenging and may require serial measurement
of IABP and assessment of organ function. It is vital to intervene
before the development of critical organ dysfunction. To
aid in the determination of timing of surgery, some surgeons
assess abdominal perfusion pressure (APP = MAP − IABP).
An APP <50 mm Hg is associated with a poor outcome and
the need for quick intervention.58 While the operating room
is prepared, volume resuscitation and low tidal volume ventilation are useful temporizing measures.

Percutaneous tracheostomy

Percutaneous Versus Surgical Tracheostomy: A Randomized Controlled
Study With Long-Term Follow-Up
Crit Care Med. 2006;34(8):2145-2152.

Abstract
Objective: To compare the safety, availability, and long-term sequelae of percutaneous vs. surgical tracheostomy.

Design: Prospective, randomized, controlled study.
Setting: Combined medical/surgical intensive care unit in a tertiary referral hospital.

Patients: Two hundred critically ill mechanically ventilated patients who required tracheostomy.

Interventions: Tracheostomy by either percutaneous tracheostomy or surgical tracheostomy performed in the
intensive care unit.

Measurements and Main Results: The primary outcome measure was the aggregate incidence of predefined
moderate or severe complications. The secondary outcome measures were the incidence of each of the components
of the primary outcome. Long-term follow-up included clinical assessment, flow volume loops, and bronchoscopy.
Both groups were well matched for age, gender, admission Acute Physiology and Chronic Health Evaluation II score,
period of endotracheal intubation, reason for intubation, and admission diagnosis. There was no statistical difference
between groups for the primary outcome. Bleeding requiring surgical intervention occurred in three percutaneous
tracheostomy patients and in no surgical tracheostomy patient (p = .2). Postoperative infection (p = .044) and
cosmetic sequelae (p = .08) were more common in surgical tracheostomy patients. There was a shorter delay from
randomization to percutaneous tracheostomy vs. surgical tracheostomy (p = .006). Long-term follow-up revealed no
complications in either group.

Conclusions: Both percutaneous tracheostomies and surgical tracheostomies can be safely performed at the
bedside by experienced, skilled practitioners.

Role of albumin in sepsis

Crit Care Med. 2011 Feb;39(2):386-91.
The role of albumin as a resuscitation fluid for patients with sepsis: a systematic review and meta-analysis.
Delaney AP, Dan A, McCaffrey J, Finfer S.
Source

Northern Clinical School, Sydney Medical School, University of Sydney, Sydney, Australia. adelaney@med.usyd.edu.au
Abstract
OBJECTIVE:

To assess whether resuscitation with albumin-containing solutions, compared with other fluids, is associated with lower mortality in patients with sepsis.
DATA SOURCES:

MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases, the metaRegister of Controlled Trials, and the Medical Editors Trial Amnesty Register.
STUDY SELECTION:

Prospective randomized clinical trials of fluid resuscitation with albumin-containing solutions compared with other fluid resuscitation regimens, which included a population or subgroup of participants with sepsis, were included.
DATA EXTRACTION:

Assessment of the validity of included studies and data extraction were conducted independently by two authors.
DATA SYNTHESIS:

For the primary analysis, the effect of albumin-containing solutions on all-cause mortality was assessed by using a fixed-effect meta-analysis.
RESULTS:

Seventeen studies that randomized 1977 participants were included in the meta-analysis. There were eight studies that included only patients with sepsis and nine where patients with sepsis were a subgroup of the study population. There was no evidence of heterogeneity, I² = 0%. The use of albumin for resuscitation of patients with sepsis was associated with a reduction in mortality with the pooled estimate of the odds ratio of 0.82 (95% confidence limits 0.67-1.0, p = .047).
CONCLUSIONS:

In this meta-analysis, the use of albumin-containing solutions for the resuscitation of patients with sepsis was associated with lower mortality compared with other fluid resuscitation regimens. Until the results of ongoing randomized controlled trials are known, clinicians should consider the use of albumin-containing solutions for the resuscitation of patients with sepsis.
Comment in

Crit Care Med. 2011 Feb;39(2):418-9.

Hering–Breuer inflation reflex

Hering–Breuer inflation reflex,

named for Josef Breuer and Ewald Hering,is a reflex triggered to prevent over-inflation of the lungs. Pulmonary stretch receptors present in the smooth muscle of the airways respond to excessive stretching of the lung during large inspirations.

Once activated, they send action potentials through large myelinated fibers of the paired vagus nerves to the inspiratory area in the medulla and apneustic area of the pons.

In response, the inspiratory area is inhibited directly and the apneustic area is inhibited from activating the inspiratory area. This inhibits inspiration, allowing expiration to occur.

high tidal volume จะ reflex ให้ ลด RR

Pleural effusion in CT

pleural effusion in CT
HU 0-100 (water-soft tissue)
1.diaphragm sign : pleural fluid lies posterior & lateral ต่อ diaphragm
ascites anterior & medial
2.interface sign : pleural fluid ที่ติดกับตับ หรือ ม้าม จะเห็นขอบไม่ชัด เนื่องจากมี diaphragm มากั้น
ascites จะเห็นขอบชัดเจน
3.displaced curs sign : pleural fluid displace diaphragmatic crus anteriorly
ascites posteriorly
4.bare area sign : ascites จะเข้าไปตรง posteromedial aspect of Rt lobe liver ไม่ได้เนื่องจากเป็นบริเวณที่ไม​่มี peritoneal cover ที่ให้ตับติดกับ posterior abdominal wall โดยตรง
pleural fluid เข้าไป ด้านหลังตับได้