Accuracy of pulse oximetry in pigmented patients

Objective. Prospective assessment of the accuracy of three pulse oximeters and  two probe sites in darkly pigmented critically·i11 patients under clinical conditions.Patients and methods. One hundred consecutive, darkly pigmented critically ill adutt patients with arterial lines in situ were studied. Patients were excluded if thehaemoglobin concentration was less than 7 g/dl and carboxyhaemoglobin or  methaemoglobin levels exceeded 2%. Pigmentation was objectively quantified with a portable EEL reflectance spectrophotometer (Evans E1ectroselenium Company, Diffusion Systems Limited. London). Reflectance was measured at nine wavelengths.Results. The degree of pigmentation as measured by percentage reflectance closely matched that of a control group of black Africans from a pigmentation study. The limits of agreement (2.6% to 5.8%), precision and bias values between pulse  oximeter and co-ox!meter readings fell within a narrow range. The 95% confidence intervals of the limits of agreement reflected a small variation in the difference between pulse oximeter and co-oximeter readings. These small differences were not clinically. significant in the pigmented patients who were enrolled in the study.Conclusion. The accuracy of pulse oximetry is not adversely affected by skin  pigmentation, and it remains a useful oxygenation monitoring device in darkly pigmented patients

Mixed symmetry superconductivity in two-dimensional Fermi liquids

We consider a 2D isotropic Fermi liquid with attraction in both $s$ and $d$ channels and examine the possibility of a superconducting state with mixed $s$ and $d$ symmetry of the gap function. We show that both in the weak coupling limit and at strong coupling, a mixed $s+id$ symmetry state is realized in a certain range of interaction. Phase transitions between the mixed and the pure symmetry states are second order. We also show that there is no stable mixed $s+d$ symmetry state at any coupling.Comment: 3 figures attached in uuencoded gzipped file

Transport and the Order Parameter of Superconducting Sr2_2RuO4_4

Recent experiments make it appear more likely that the order parameter of the unconventional superconductor Sr$_2$RuO$_4$ has a spin-triplet $f$-wave symmetry. We study ultrasonic absorption and thermal conductivity of superconducting Sr$_2$RuO$_4$ and fit to the recent data for various $f$-wave candidates. It is shown that only $f_{x^2-y^2}$-wave symmetry can account qualitatively for the transport data.Comment: 4 pages, 2 figures, references added and update

The Critical Care Society of Southern Africa consensus statement on ICU triage and rationing (ConICTri)

BACKGROUND: In South Africa (SA), intensive care is faced with the challenge of resource scarcity as well as an increasing demand for intensive care unit (ICU) services. ICU services are expensive, and practitioners in low- to middle-income countries experience daily the consequences of limited resources. Critically limited resources necessitate that rationing and triage (prioritisation) decisions are frequently necessary in SA, particularly in the publicly funded health sector. PURPOSE: The purpose of this consensus statement is to examine key questions that arise when considering the status of ICU resources in SA, and more specifically ICU admission, rationing and triage decisions. The accompanying guideline in this issue is intended to guide frontline triage policy and ensure the best utilisation of intensive care in SA, while maintaining a fair distribution of available resources. Fair and efficient triage is important to ensure the ongoing provision of high-quality care to adult patients referred for intensive care. RECOMMENDATIONS: In response to 14 key questions developed using a modified Delphi technique, 29 recommendations were formulated and graded using an adapted GRADE score. The 14 key questions addressed the status of the provision of ICU services in SA, the degree of resource restriction, the efficiency of resource management, the need for triage, and how triage could be most justly implemented. Important recommendations included the need to formally recognise and accurately quantify the provision of ICU services in SA by national audit; actively seek additional resources from governmental bodies; consider methods to maximise the efficiency of ICU care; evaluate lower level of care alternatives; develop a triage guideline to assist policy-makers and frontline practitioners to implement triage decisions in an efficient and fair way; measure and audit the consequence of triage; and promote research to improve the accuracy and consistency of triage decisions. The consensus document and guideline should be reviewed and revised appropriately within 5 years. CONCLUSIONS: In recognition of the absolute need to limit patient access to ICU because of the lack of sufficient intensive care resources in public hospitals, recommendations and a guideline have been developed to guide policy-making and assist frontline triage decision-making in SA. These documents are not a complete plan for quality practice but rather the beginning of a long-term initiative to engage clinicians, the public and administrators in appropriate triage decision-making, and promote systems that will ultimately maximise the efficient and fair use of available ICU resources.http://www.samj.org.zapm2020SurgeryCritical Car

Pain distress : the negative emotion associated with procedures in ICU patients

The intensity of procedural pain in intensive care unit (ICU) patients is well documented. However, little is known about procedural pain distress, the psychological response to pain. Post hoc analysis of a multicenter, multinational study of procedural pain. Pain distress was measured before and during procedures (0-10 numeric rating scale). Factors that influenced procedural pain distress were identified by multivariable analyses using a hierarchical model with ICU and country as random effects. A total of 4812 procedures were recorded (3851 patients, 192 ICUs, 28 countries). Pain distress scores were highest for endotracheal suctioning (ETS) and tracheal suctioning, chest tube removal (CTR), and wound drain removal (median [IQRs] = 4 [1.6, 1.7]). Significant relative risks (RR) for a higher degree of pain distress included certain procedures: turning (RR = 1.18), ETS (RR = 1.45), tracheal suctioning (RR = 1.38), CTR (RR = 1.39), wound drain removal (RR = 1.56), and arterial line insertion (RR = 1.41); certain pain behaviors (RR = 1.19-1.28); pre-procedural pain intensity (RR = 1.15); and use of opioids (RR = 1.15-1.22). Patient-related variables that significantly increased the odds of patients having higher procedural pain distress than pain intensity were pre-procedural pain intensity (odds ratio [OR] = 1.05); pre-hospital anxiety (OR = 1.76); receiving pethidine/meperidine (OR = 4.11); or receiving haloperidol (OR = 1.77) prior to the procedure. Procedural pain has both sensory and emotional dimensions. We found that, although procedural pain intensity (the sensory dimension) and distress (the emotional dimension) may closely covary, there are certain factors than can preferentially influence each of the dimensions. Clinicians are encouraged to appreciate the multidimensionality of pain when they perform procedures and use this knowledge to minimize the patient's pain experience.Peer reviewe

Delayed upper airway obstruction: A life-threatening complication of Dettol poisoning

Dettol liquid is a commonly used household disinfectant and although it is labelled nonpoisonous, serious respiratory complications have been reported in up to 8% of cases of Dettol ingestion. We report a case in which the delayed onset of upper airway obstruction was treated with emergency awake, fibreoptic guided nasotracheal intubation. Based on information available in published cases and on our own experience, we suggest that patients who have ingested large volumes of Dettol, have a history of vomiting or unprotected lavage, or have evidence of ongoing oropharyngeal inflammation, are at high risk of this complication. They should be closely observed for at least 48 h after ingestion and the facilities and staff required for emergency airway management should be immediately available

A comparison of central venous pressure and common iliac venous pressure in critically ill mechanically ventilated patients

Objective: To investigate the possibility of using common iliac venous pressure (CIVP) as an alternative to superior vena cava pressure (SVCP) in mechanically ventilated, critically ill, adult patients. Design: A randomized, blinded comparison. Setting: Multidisciplinary intensive care unit at a university teaching hospital. Patients: Twenty mechanically ventilated, critically ill, adult patients. Interventions: None. Measurements and Main Results: All patients had a catheter in situ for measuring the SVCP. A new triple-lumen catheter, with a length ranging from 15 to 20 cm, was placed into the common iliac vein via the femoral route. The SVCP and CIVP were simultaneously measured at hourly intervals for 6 hrs. Positive end-expiratory pressure, mean airway pressure, and intra-abdominal pressure were measured at the same time intervals. For 140 paired measurements of CIVP and SVCP in 20 patients, the mean difference was 0.1 +/- 1.06 (SD) mm Hg (95% confidence interval -0.10 to 0.25); the limits of agreement were -2.04 to 2.20 mm Hg (95% confidence interval -2.34 to 2.50). Mean airway pressure, intra-abdominal pressure, and positive end-expiratory pressure had no measurable effect on the difference between SVCP and CIVP. Serious complications arising from insertion of the catheter through the femoral route were not observed. Conclusion: For clinical purposes, CIVP measured by a catheter of 15 to 20 cm placed through the femoral route is interchangeable with SVCP in mechanically ventilated adult patients. This finding provides an alternative route for assessment of central venous pressure when other routes are not appropriate

Gastric tonometry and prediction of outcome in the critically ill#Arterial to intramucosal pH gradient and carbon dioxide gradient

Splanchnic ischaemia is thought to be of central importance in the development of multi-organ failure and hence death in critically ill patients. It has been suggested that the arterial to gastric intramucosal pH gradient and the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood are more sensitive markers of splanchnic ischaemia than gastric intramucosal pH itself and thus should be predictors of mortality in the critically ill. We studied 62 critically ill patients within 6 h of admission to the intensive care unit and found no significant difference at 0, 12 or 24 h after admission to the study in either the arterial to gastric intramucosal pH gradient or the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood between survivors and nonsurvivors. We conclude that in contrast to gastric intramucosal pH neither the arterial to gastric intramucosal pH gradient nor the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood distinguish survivors from nonsurvivors