Exploring the limits of prolonged apnoea with high-flow nasal oxygen: an observational study

High-flow nasal oxygen is increasingly used for oxygenation during apnoea. Extending apnoea duration using this technique has mainly been investigated during minor laryngeal surgery, but it is unclear how long it can be administered for before it should be discontinued due to acidosis. We aimed to describe the dynamics of arterial blood gases during apnoeic oxygenation with high-flow nasal oxygen with jaw thrust only, to explore the limits of this technique. We included adult orthopaedic patients scheduled for general anaesthesia. After pre-oxygenation, anaesthesia with neuromuscular blockade was induced and high-flow nasal oxygen (70 l.min^-1 ) was continued with jaw thrust as the only means of airway management, with monitoring of vital signs and arterial blood gas sampling every 5 minutes. Apnoeic oxygenation with high-flow nasal oxygen was discontinued when arterial carbon dioxide tension (PaCO₂ ) exceeded 12 kPa or pH fell to 7.15. This technique was used in 35 patients and median (IQR [range]) apnoea time was 25 (20-30 [20-45]) min and was discontinued in all patients when pH fell to 7.15. The mean (SD) PaCO₂ increase was 0.25 (0.06) kPa.min^-1 but it varied substantially (range 0.13-0.35 kPa.min^-1 ). Mean (SD) arterial oxygen tension was 48.6 (11.8) kPa when high-flow nasal oxygen was stopped. Patients with apnoea time > 25 minutes were significantly older (p = 0.025). We conclude that apnoeic oxygenation with high-flow nasal oxygen resulted in a significant respiratory acidosis that varies substantially on the individual level, but oxygenation was maintained.

Combination therapy for multidrug-resistant cytomegalovirus disease

Multidrug-resistant (MDR) cytomegalovirus (CMV) emerged after transient responses to ganciclovir, foscarnet, and cidofovir in a CMV-seropositive recipient who underwent allogeneic hematopoietic stem cell transplantation from a CMV-seronegative donor. Experimental treatments using leflunomide and artesunate failed. Re-transplantation from a CMV-seropositive donor supported by adoptive transfer of pp65-specific T cells and maribavir was followed by lasting suppression. This case illustrates that successful MDR CMV therapy may require individualized multidisciplinary approaches.

Comparative analysis of assays for detection of cell-mediated immunity toward cytomegalovirus and M. tuberculosis in samples from deceased organ donors

Cell-mediated immunity assays could be valuable for risk assessment of organ donors, but no data exist on their feasibility in deceased donors. In this study, 105 deceased donors (52.3 ± 16.9 years) were screened at the time of organ procurement. Pathogen-specific stimulation was performed using a cytomegalovirus (CMV) lysate, tuberculin (purified protein derivative [PPD]) and soluble Mycobacterium tuberculosis-specific ESAT-6/CFP-10 proteins in combination with an in-house fluorescence-activated cell sorting (FACS) assay or commercial assay formats (QuantiFERON-CMV/TB for ELISA, T-SPOT.TB for ELISPOT). CMV-IgG antibody titers were determined as gold standard for CMV infection; 51.4% of samples were CMV seropositive. Indeterminate results were observed in 47.6% of ELISA, 12.5% of FACS and 0% of ELISPOT assays. Agreement with serology was highest for FACS (95.6%, κ = 0.91), followed by ELISPOT (84.0%, κ = 0.68) and ELISA (80.0%, κ = 0.60). Agreement between ELISA and serology increased if the CMV lysate was used as stimulus (96.7%, κ = 0.92). Among the T cell assays, agreement between ELISPOT and FACS was highest (κ = 0.70). PPD-positive results among valid samples differed between assays (26.5% for ELISA, 23.1% for FACS and 50.5% for ELISPOT); 2.0% were QuantiFERON-TB positive, 3.3% were ESAT-6/CFP-10-positive in FACS and 13.4% were positive in the T-SPOT.TB assay. In conclusion, cellular immunity may be analyzed from samples of deceased donors, although the assays differ in the rate of positivity and indeterminate results.

BK polyomavirus-specific cellular immune responses are age-dependent and strongly correlate with phases of virus replication

BK polyomavirus (BKPyV) infection is widespread and typically asymptomatic during childhood, but may cause nephropathy in kidney transplant recipients. However, there is only limited knowledge on BKPyV-specific immunity in children and adults, and its role in BKPyV-replication and disease posttransplant. We therefore characterized BKPyV-specific immunity from 122 immunocompetent individuals (1-84 years), 38 adult kidney recipients with (n = 14) and without BKPyV-associated complications (n = 24), and 25 hemodialysis (HD) patients. Blood samples were stimulated with overlapping peptides of BKPyV large-T antigen and VP1 followed by flow-cytometric analysis of activated CD4 T cells expressing interferon-γ, IL-2 and tumor necrosis factor-α. Antibody-levels were determined using enzyme-linked immunosorbent assay. Both BKPyV-IgG levels and BKPyV-specific CD4 T cell frequencies were age-dependent (p = 0.0059) with maximum levels between 20 and 30 years (0.042%, interquartile range 0.05%). Transplant recipients showed a significantly higher BKPyV-specific T cell prevalence (57.9%) compared to age-matched controls (21.7%) or HD patients (28%, p = 0.017). Clinically relevant BKPyV-replication was associated with elevated frequencies of BKPyV-specific T cells (p = 0.0002), but decreased percentage of cells expressing multiple cytokines (p = 0.009). In conclusion, BKPyV-specific cellular immunity reflects phases of active BKPyV-replication either after primary infection in childhood or during reactivation after transplantation. Combined analysis of BKPyV-specific T cell functionality and viral loads may improve individual risk assessment.

PD-1 analysis on CD28(-) CD27(-) CD4 T cells allows stimulation-independent assessment of CMV viremic episodes in transplant recipients

Expression of the inhibitory receptor programmed death 1 (PD-1) on cytomegalovirus (CMV)-specific CD4 T cells defines a phenotype associated with CMV viremia in transplant recipients. Moreover, CD28(-) CD27(-) double negativity is known as a typical phenotype of CMV-specific CD4 T cells. Therefore, the co-expression of inhibitory receptors on CD28(-) CD27(-) CD4 T cells was assessed as a rapid, stimulation-independent parameter for monitoring CMV complications after transplantation. Ninety-three controls, 67 hemodialysis patients and 81 renal transplant recipients were recruited in a cross-sectional and longitudinal manner. CMV-specific CD4 T cell levels quantified after stimulation were compared to levels of CD28(-) CD27(-) CD4 T cells. PD-1 and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) expression on CD28(-) CD27(-) CD4 T cells were related to viremia. A percentage of ≥0.44% CD28(-) CD27(-) CD4 T cells defined CMV seropositivity (93.3% sensitivity, 97.1% specificity), and their frequencies correlated strongly with CMV-specific CD4 T cell levels after stimulation (r = 0.73, p < 0.0001). Highest PD-1 expression levels on CD28(-) CD27(-) CD4 T cells were observed in patients with primary CMV viremia and reactivation (p < 0.0001), whereas CTLA-4 expression was only elevated during primary CMV viremia (p < 0.05). Longitudinal analysis showed a significant increase in PD-1 expression in relation to viremia (p < 0.001), whereas changes in nonviremic patients were nonsignificant. In conclusion, increased PD-1 expression on CD28(-) CD27(-) CD4 T cells correlates with CMV viremia in transplant recipients and may serve as a specific, stimulation-independent parameter to guide duration of antiviral therapy.

Blockade of programmed death receptor-1 signaling restores expression of mostly proinflammatory cytokines in anergic cytomegalovirus-specific T cells

BACKGROUND

Programmed death receptor-1 (PD-1) compromises cytomegalovirus (CMV)-specific T-cell responses and has been linked to CMV viremia after transplantation. An impaired functional and proliferative capacity of PD-1-positive CMV-specific T cells may be reversed by the antibody-mediated blockade of PD-1 signaling. However, knowledge is limited on changes in "cytokinome" expression profiles associated with reversal of functional exhaustion.

METHODS

The "cytokinome" was analyzed by 27-plex Luminex technology comparing renal transplant recipients with low (n = 5) and high (n = 5) PD-1 expression on CMV-specific T cells. The effect of blocking PD-1 by PD-ligand (PD-L) antibodies on restoration of cytokine expression was examined.

RESULTS

CMV-specific cytokine release and proliferation was lower in patients with high PD-1 expression on CMV-specific T cells. Antibody-mediated blockade of PD-L in CMV-stimulated samples restored expression levels of interleukin (IL)-1β, IL-2, IL-6, IL-9, IL-10, granulocyte colony-stimulating factor, interferon-γ, macrophage inflammatory protein-1α, and tumor necrosis factor-α. By contrast, no profound effect was observed for controls or patients with low PD-1 expression, or in staphylococcal enterotoxin B-stimulated cells.

CONCLUSION

Taken together, this pilot study provides evidence that a high PD-1 expression on CMV-specific T cells actively impairs proliferation and "cytokinome" responses in an antigen-specific manner. Importantly, blockade of PD-L restores CMV-specific T-cell proliferation and expression of a panel of different proinflammatory and/or type 1 cytokines, suggesting a common but as yet unknown regulatory principle. We conclude that PD-1 exhaustion is reversible and potentially amenable to therapeutic ex vivo and possibly in vivo manipulation. However, detailed knowledge of the differential effects on the "cytokinome" will be necessary to increase the safety and the efficacy of such manipulations.

A WORLD PERSPECTIVE ON RENAL CARE: THE CHALLENGES OF PREVENTION AND TREATMENT

It is a special privilege to address the renal care professionals who so skilfully carry out renal replacement treatment in all the countries of the European Union. Approximately one million people a year die from renal diseases. There are currently 1,065,000 people on haemodialysis worldwide. Ninety percent of them live in North America, Japan and Europe, whose population is less than 20% of the world's total. What this tells us is that dialysis isn't available in developing countries, as one could expect that the number of both pre-dialysis patients and those needing dialysis would be about the same in the developed and developing world.

PD-1 expression and IL-2 loss of cytomegalovirus- specific T cells correlates with viremia and reversible functional anergy

Cytomegalovirus (CMV) represents a major cause of infectious complications after transplantation. Recently, chronic infections with lymphocyte choriomeningitis virus (LCMV), HIV or HCV were shown to be associated with functionally exhausted T cells characterized by high expression of the programmed death (PD)-1 molecule and altered cytokine expression patterns. We therefore hypothesized that functional exhaustion of CMV-specific CD4 T cells may determine impaired CMV control in patients after renal transplantation. In viremic transplant recipients, a significantly higher proportion of CMV-specific CD4 T cells was PD-1 positive (median 40.9%, 17.0-88.7%) as compared to nonviremic transplant patients (8.8%, 0.8-80.5%), dialysis patients (8.8%, 0-36.7%) or controls (3.2%, 0.3-15.4%, p < 0.0001). In line with functional impairment, PD-1-positive T cells produced significantly less IFNgamma as compared to PD-1-negative T cells (p < 0.0001). Moreover, unlike controls or nonviremic patients, CMV-specific T cells from viremic patients showed a significant loss of IL-2 production (p < 0.0001). Interestingly, functional anergy of CMV-specific CD4 T cells was reversible in that antibody-mediated blockade of PD-1 signaling with its ligands PD-L1/-L2 led to an up to 10-fold increase in CMV-specific proliferation. In conclusion, expression of PD-1 defines a reversible defect of CMV-specific CD4 T cells that is associated with viremia, and blocking PD-1 signaling may provide a potential target for enhancing the function of exhausted T cells in chronic CMV infection.

[Transesophageal echocardiography for non-cardiac surgery patients: superfluous luxury or essential diagnostic tool?]

BACKGROUND

The value of transesophageal echocardiography (TEE) in non-cardiac critically ill patients has barely been studied.

MATERIALS AND METHODS

Over a period of 4 years TEE was used prospectively to evaluate patients with acute hemodynamic instability in non-cardiac critically ill patients in addition to standard care.

RESULTS

A total of 363 TEE studies were performed in 339 selected patients. Volume depletion (169/47%) and regional wall motion abnormalities (97/27%) were the most frequent findings followed by global left ventricular dysfunction (79/22%). Of the TEE studies, 203 (56%) provided additional information with therapeutic relevance in 164 (45%) cases.

CONCLUSIONS

Transesophageal echocardiography provides additional information in critically ill non-cardiac patients with unexplained hemodynamic instability. In the majority of cases a clinical diagnosis is confirmed or improvement of volume resuscitation and catecholamine therapy can be achieved. In the minority of patients the results of TEE lead to distinct changes in medical management. Whether this improved diagnostic accuracy favours outcome, still needs to be evaluated.

Effect of epidural bupivacaine vs combined epidural bupivacaine and morphine on gastrointestinal function and pain after major gynaecological surgery

In a double-blind study, we investigated the effects of postoperative epidural local anaesthetic, with or without addition of epidural morphine, on postoperative pain and gastrointestinal function in patients scheduled for radical hysterectomy and pelvic lymphadenectomy. Forty patients were randomized into two study groups: 48-h postoperative epidural 0.2% bupivacaine 8 ml h(-1) (bupi group) or 48-h postoperative epidural 0.2% bupivacaine/morphine 50 microg at 4 ml h(-1) (bupi/morph group). Patients were observed for at least 96 h after surgery. No differences in pain at rest, during cough or mobilization were observed. Patients in the bupi group requested a significant greater amount of supplementary analgesics, but times to first flatus and defaecation were reduced compared with patients in the bupi/morph group. Itching was a significant problem in patients in the bupi/morph group. No differences in postoperative nausea and vomiting, mobilization or time to discharge from hospital were observed between groups. The addition of morphine to postoperative epidural bupivacaine has only limited effect on pain relief and increases time to normalization of gastrointestinal function.

Effect of peri- and postoperative epidural anaesthesia on pain and gastrointestinal function after abdominal hysterectomy

In a double blind study we have investigated the effects of epidural local anaesthesia (LA), when added to general anaesthesia (GA) and postoperative paracetamol and NSAID, on postoperative pain and gastrointestinal function in patients undergoing open hysterectomy. Sixty patients were randomized into three study groups: GA, and postoperative paracetamol and NSAID (GA, n=20); GA, paracetamol, NSAID, intraoperative epidural lidocaine and 24-h postoperative epidural saline (Saline, n=20); or GA, paracetamol, NSAID, intraoperative epidural lidocaine and 24-h postoperative epidural bupivacaine (Bupi, n=20). Patients were observed for 72 h postoperatively. Pain at rest, during cough, and mobilization, request for supplementary morphine, and time to first postoperative flatus, was reduced in patients receiving 24-h postoperative epidural anaesthesia, compared with the two other groups. However, these effects of epidural LA, were not sustained beyond the period of infusion, and no differences in PONV, time to first postoperative defecation, mobilization or time to discharge from hospital were observed between groups. A 24 h postoperative epidural infusion with bupivacaine, when added to postoperative paracetamol and NSAID, reduces pain and opioid requirements, but has only limited effects on gastrointestinal function and patient recovery.

Effect of systemic adenosine on pain and secondary hyperalgesia associated with the heat/capsaicin sensitization model in healthy volunteers

BACKGROUND AND OBJECTIVES

Adenosine is an endogenous compound that may have analgesic effects. Results from clinical trials are not consistent, however, and there is a need for large-scale, randomized, placebo-controlled studies to clarify the role of adenosine in the treatment of pain states, including acute nociceptive pain and pain involving central sensitization.

METHODS

The analgesic and antihyperalgesic effect of systemic adenosine on the heat/capsaicin sensitization model of experimental pain was investigated in 25 healthy human volunteers. Sensitization was produced by heating the skin to 45 degrees C for 5 minutes, followed by a 30-minute application of 0.075% capsaicin cream, and maintained by periodically reheating the sensitized skin to 40 degrees C for 5 minutes at 40-minute intervals. Subjects received intravenous adenosine 60 microg/kg/min or saline for 85 minutes. Areas of secondary hyperalgesia to von Frey hair and brush stimulation, heat-pain detection thresholds (HPDTs) in normal and sensitized skin, and painfulness of stimulation with 45 degrees C for 1 minute (LTS) in normal skin were quantified before, during, and after study drug infusion.

RESULTS

Systemic adenosine had no effect on the area of secondary hyperalgesia to von Frey hair or brush stimulation, HPDT in normal or sensitized skin, or painfulness of LTS in normal skin.

CONCLUSION

We conclude that adenosine has no effect on acute nociceptive pain induced by heat stimulation or on secondary hyperalgesia induced by heat/capsaicin sensitization in healthy volunteers.

Effect of intravenous magnesium on pain and secondary hyperalgesia associated with the heat/capsaicin sensitization model in healthy volunteers

We investigated the effects of i.v. magnesium on secondary hyperalgesia following heat/capsaicin stimulation in human volunteers. Twenty-five volunteers were included in this double blind, randomized, crossover study. Sensitization was induced in the volunteers, who were then subjected to either i.v. saline or magnesium sulphate. No analgesic or antihyperalgesic effect could be demonstrated in sensitized skin during infusion of magnesium. In contrast, painfulness of thermal stimulation was increased in normal skin. These results suggest that i.v. magnesium has no important analgesic effects in clinically relevant doses.

The effect of systemic lidocaine on pain and secondary hyperalgesia associated with the heat/capsaicin sensitization model in healthy volunteers

Although effective in neuropathic pain, the efficacy of systemic lidocaine in non-neuropathic pain remains uncertain. We investigated the analgesic effect of systemic lidocaine on the heat/capsaicin sensitization model of experimental pain in 24 volunteers. Sensitization was produced by heating the skin to 45 degrees C for 5 min, followed by a 30-min application of 0.075% capsaicin cream, and maintained by periodically reheating the sensitized skin. Subjects received IV lidocaine (bolus 2 mg/kg, then infusion 3 mg. kg. h), or saline for 85 min. Areas of secondary hyperalgesia, heat pain detection thresholds, and painfulness of stimulation with 45 degrees C for 1 min (long thermal stimulation) were quantified. Systemic lidocaine reduced the area of secondary hyperalgesia to brush, but not to von Frey hair stimulation. Lidocaine did not alter heat pain detection thresholds or painfulness of long thermal stimulation in normal skin. We conclude that, at infusion rates in the low- to mid-antiarrhythmic range, lidocaine has no effect on acute nociceptive pain but does have a limited and selective effect on secondary hyperalgesia.

IMPLICATIONS

The efficacy of systemic lidocaine in nonneuropathic pain remains uncertain. This study investigates the effect of systemic lidocaine on experimental-induced hyperalgesia in 25 volunteers. Hyperalgesia was induced by using an experimental pain model that uses heat and capsaicin in combination. Systemic lidocaine showed a selective effect on secondary hyperalgesia.

Effect of continuous epidural 0.2% ropivacaine vs 0.2% bupivacaine on postoperative pain, motor block and gastrointestinal function after abdominal hysterectomy

We have investigated the effect of 24-h postoperative continuous epidural infusion of 0.2% ropivacaine or 0.2% bupivacaine 8 ml h-1 on pain, request for supplementary analgesics, motor block and gastrointestinal function, in a double-blind, randomized study in 60 patients undergoing open hysterectomy. There were no significant differences between groups in pain, number of patients requesting supplementary analgesics, motor block, ability to walk or time to first flatus or stool. In the subgroup of patients who received supplementary analgesics, patients in the ropivacaine group received significantly more ketorolac than patients in the bupivacaine group. Time to discharge from hospital was similar with ropivacaine and bupivacaine.

Cytokine levels affected by gamma-linolenic acid

This study was undertaken to assess whether gamma-linolenic acid (GLA) in the form of evening primrose oil (EPO) could affect rat serum cytokines, interferon-gamma (IFN-gamma), monocyte chemotactic protein-1 (MCP-1) and tumour necrosis factor-alpha (TNF-alpha). The following diets were administered: control, glucan, Freund's adjuvant and glucan plus Freund's adjuvant with and without GLA. In the presence of GLA, the IFN-gamma and MCP-1 levels were significantly decreased in contrast to the control group of TNF-alpha, which was significantly stimulated. On account of interaction between diets and GLA, the remaining diet groups of TNF-alpha were either not affected or were inhibited in the presence of GLA. The observations indicate that GLA may modulate the level of serum IFN-gamma, MCP-1 and TNF-alpha, which may be a worthwhile line of treatment in certain human diseases.

Effect of systemic N-methyl-D-aspartate receptor antagonist (dextromethorphan) on primary and secondary hyperalgesia in humans

Dextromethorphan is a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist known to inhibit wind-up and central hyperexcitability of dorsal horn neurones. We studied 24 healthy, unmedicated male volunteers, aged 21-28 yr, in a randomized, double-blind, placebo-controlled, crossover study. Burn injuries were produced on the medial surface of the dominant calf with a 25 x 50 mm rectangular thermode. On three separate days, at least 1 week apart, subjects were given oral dextromethorphan 60 mg, 120 mg or placebo. Dextromethorphan reduced the magnitude of secondary hyperalgesia to pinprick but not to stroke. Dextromethorphan had no influence on primary hyperalgesia, pain during prolonged noxious heat stimulation or heat pain detection thresholds in undamaged skin. Side effects were frequent but clinically acceptable. The effects of dextromethorphan were in agreement with experimental studies indicating that dextromethorphan is a NMDA receptor antagonist. The effects of dextromethorphan in the burn injury model were similar to those of ketamine and distinct from those of local anaesthetics and opioids.

The road to recovery for elders after CABG

One year later, 88% of these octogenarians said they would undergo CABG again. Here's how nursing care set them on the right course.

Infants' perception of similarity between live people and their photographs

5-month-old infants who had been habituated to a live face showed no change in fixation time when presented with an immediately following photographic slide of that same face, while they showed an increase in fixation time (dishabituation) to a photographic slide of a novel face of different sex, hair color, and hair style. The similarity in responses to the live person and his photograph indictaes that some identification of people in photographs is possible even in the absence of extended prior developmental experience with pictures. A second experiment found that 5-month-old Ss exhibited the same amount of looking when a live face was followed either by its own photograph or by a photograph of a novel person of like sex, hair color, and hair style. Apparently, these Ss used only rather gross physiognomic features to perceive a similarity between a live person and that person's photograph.