John G. Laffey

Epidemiology, Patterns of Care, and Mortality for Patients With Acute Respiratory Distress Syndrome in Intensive Care Units in 50 Countries

IMPORTANCE Limited information exists about the epidemiology, recognition, management, and outcomes of patients with the acute respiratory distress syndrome (ARDS). OBJECTIVES To evaluate intensive care unit (ICU) incidence and outcome of ARDS and to assess clinician recognition, ventilation management, and use of adjuncts-for example prone positioning-in routine clinical practice for patients fulfilling the ARDS Berlin Definition. DESIGN, SETTING, AND PARTICIPANTS The Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) was an international, multicenter, prospective cohort study of patients undergoing invasive or noninvasive ventilation, conducted during 4 consecutive weeks in the winter of 2014 in a convenience sample of 459 ICUs from 50 countries across 5 continents. EXPOSURES Acute respiratory distress syndrome. MAIN OUTCOMES AND MEASURES The primary outcome was ICU incidence of ARDS. Secondary outcomes included assessment of clinician recognition of ARDS, the application of ventilatory management, the use of adjunctive interventions in routine clinical practice, and clinical outcomes from ARDS. RESULTS Of 29,144 patients admitted to participating ICUs, 3022 (10.4%) fulfilled ARDS criteria. Of these, 2377 patients developed ARDS in the first 48 hours and whose respiratory failure was managed with invasive mechanical ventilation. The period prevalence of mild ARDS was 30.0% (95% CI, 28.2%-31.9%); of moderate ARDS, 46.6% (95% CI, 44.5%-48.6%); and of severe ARDS, 23.4% (95% CI, 21.7%-25.2%). ARDS represented 0.42 cases per ICU bed over 4 weeks and represented 10.4% (95% CI, 10.0%-10.7%) of ICU admissions and 23.4% of patients requiring mechanical ventilation. Clinical recognition of ARDS ranged from 51.3% (95% CI, 47.5%-55.0%) in mild to 78.5% (95% CI, 74.8%-81.8%) in severe ARDS. Less than two-thirds of patients with ARDS received a tidal volume 8 of mL/kg or less of predicted body weight. Plateau pressure was measured in 40.1% (95% CI, 38.2-42.1), whereas 82.6% (95% CI, 81.0%-84.1%) received a positive end-expository pressure (PEEP) of less than 12 cm H2O. Prone positioning was used in 16.3% (95% CI, 13.7%-19.2%) of patients with severe ARDS. Clinician recognition of ARDS was associated with higher PEEP, greater use of neuromuscular blockade, and prone positioning. Hospital mortality was 34.9% (95% CI, 31.4%-38.5%) for those with mild, 40.3% (95% CI, 37.4%-43.3%) for those with moderate, and 46.1% (95% CI, 41.9%-50.4%) for those with severe ARDS. CONCLUSIONS AND RELEVANCE Among ICUs in 50 countries, the period prevalence of ARDS was 10.4% of ICU admissions. This syndrome appeared to be underrecognized and undertreated and associated with a high mortality rate. These findings indicate the potential for improvement in the management of patients with ARDS. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT02010073.

The systemic inflammatory response to cardiac surgery: Implications for the anesthesiologist

THE purpose of this review is to evaluate recent developments in our understanding of the inflammatory response to cardiac surgery. Scientific knowledge in this field is continually expanding, potentially significant advances are regularly reported, and this area constitutes a major interface of clinical and basic scientific research. The review is divided into four major sections. The first section describes the pathophysiology of the inflammatory response to cardiac surgery. Factors that influence the extent of the inflammatory response, including the immunomodulatory effects of drugs commonly administered perioperatively, are discussed in the second section. The third section examines the evidence that the inflammatory response contributes to adverse perioperative events, in particular organ dysfunction, while the final section evaluates potential therapeutic strategies to control this response. The review concludes with a summary of potential future research directions and key deficiencies in our knowledge regarding the inflammatory response to cardiac surgery.

The Analgesic Efficacy of Transversus Abdominis Plane Block After Abdominal Surgery: A Prospective Randomized Controlled Trial

BACKGROUND:The transversus abdominis plane (TAP) block is a novel approach for blocking the abdominal wall neural afferents via the bilateral lumbar triangles of Petit. We evaluated its analgesic efficacy in patients during the first 24 postoperative hours after abdominal surgery, in a randomized, controlled, double-blind clinical trial. METHODS:Thirty-two adults undergoing large bowel resection via a midline abdominal incision were randomized to receive standard care, including patient-controlled morphine analgesia and regular nonsteroidal antiinflammatory drugs and acetaminophen (n = 16), or to undergo TAP block (n = 16) in addition to standard care (n = 16). After induction of anesthesia, 20 mL of 0.375% levobupivacaine was deposited into the transversus abdominis neuro-fascial plane via the bilateral lumbar triangles of Petit. Each patient was assessed by a blinded investigator in the postanesthesia care unit and at 2, 4, 6, and 24 h postoperatively. RESULTS:The TAP block reduced visual analog scale pain scores (TAP versus control, mean ± sd) on emergence (1 ± 1.4 vs 6.6 ± 2.8, P < 0.05), and at all postoperative time points, including at 24 h (1.7 ± 1.7 vs 3.1 ± 1.5, P < 0.05). Morphine requirements in the first 24 postoperative hours were also reduced (21.9 ± 8.9 mg vs 80.4 ± 19.2 mg, P < 0.05). There were no complications attributable to the TAP block. All TAP patients reported high levels of satisfaction with their postoperative analgesic regimen. CONCLUSIONS:The TAP block provided highly effective postoperative analgesia in the first 24 postoperative hours after major abdominal surgery.

The analgesic efficacy of transversus abdominis plane block after cesarean delivery: a randomized controlled trial.

BACKGROUND:The transversus abdominis plane (TAP) block is an effective method of providing postoperative analgesia in patients undergoing midline abdominal wall incisions. We evaluated its analgesic efficacy over the first 48 postoperative hours after cesarean delivery performed through a Pfannensteil incision, in a randomized controlled, double-blind, clinical trial. METHODS:Fifty women undergoing elective cesarean delivery were randomized to undergo TAP block with ropivacaine (n = 25) versus placebo (n = 25), in addition to standard postoperative analgesia comprising patient-controlled IV morphine analgesia and regular diclofenac and acetaminophen. All patients received a standard spinal anesthetic, and at the end of surgery, a bilateral TAP block was performed using 1.5 mg/kg ropivacaine (to a maximal dose of 150 mg) or saline on each side. Each patient was assessed postoperatively by a blinded investigator: in the postanesthesia care unit and at 2, 4, 6, 12, 24, 36, and 48 h postoperatively. RESULTS:The TAP block with ropivacaine compared with placebo reduced postoperative visual analog scale pain scores. Mean (± sd) total morphine requirements in the first 48 postoperative hours were also reduced (66 ± 26 vs 18 ± 14 mg, P < 0.001), as was the 12-h interval morphine consumption up to 36 h postoperatively. The incidence of sedation was reduced in patients undergoing TAP blockade. There were no complications attributable to the TAP block. CONCLUSIONS:The TAP block, as a component of a multimodal analgesic regimen, provided superior analgesia when compared with placebo block up to 48 postoperative hours after elective cesarean delivery.

The Transversus Abdominis Plane Block Provides Effective Postoperative Analgesia in Patients Undergoing Total Abdominal Hysterectomy

BACKGROUND:Patients undergoing total abdominal hysterectomy suffer significant postoperative pain. The transversus abdominis plane (TAP) block is a recently described approach to providing analgesia to the anterior abdominal wall. We evaluated the analgesic efficacy of the TAP block in patients undergoing total abdominal hysterectomy via a transverse lower abdominal wall incision, in a randomized, controlled, double-blind clinical trial. METHODS:Fifty females undergoing elective total abdominal hysterectomy were randomized to undergo TAP block with ropivacaine (n = 24) versus placebo (n = 26) in addition to standard postoperative analgesia comprising patient-controlled IV morphine analgesia and regular diclofenac and acetaminophen. All patients received a general anesthetic and, before surgical incision, a bilateral TAP block was performed using 1.5 mg/kg ropivacaine (to a maximal dose of 150 mg) or saline on each side. Each patient was assessed postoperatively by a blinded investigator in the postanesthesia care unit and at 2, 4, 6, 12, 24, 36, 48 h postoperatively. RESULTS:The TAP block with ropivacaine reduced postoperative visual analog scale pain scores compared to placebo block. Mean (±sd) total morphine requirements in the first 48 postoperative hours were also reduced (55 ± 17 mg vs 27 ± 20 mg, P < 0.001). The incidence of sedation was reduced in patients undergoing TAP blockade. There were no complications attributable to the TAP block. CONCLUSIONS:The TAP block, as a component of a multimodal analgesic regimen, provided superior analgesia when compared to placebo block up to 48 postoperative hours after elective total abdominal hysterectomy.

Transversus abdominis plane block: a cadaveric and radiological evaluation.

Background and Objectives: The abdominal wall is a significant source of pain after abdominal surgery. Anterior abdominal wall analgesia may assist in improving postoperative analgesia. We have recently described a novel approach to block the abdominal wall neural afferents via the bilateral lumbar triangles of Petit, which we have termed a transversus abdominis plane block. The clinical efficacy of the transversus abdominis plane block has recently been demonstrated in a randomized controlled clinical trial of adults undergoing abdominal surgery. Methods: After institutional review board approval, anatomic studies were conducted to determine the deposition and spread of methylene blue injected into the transversus abdominis plane via the triangles of Petit. Computerized tomographic and magnetic resonance imaging studies were then conducted in volunteers to ascertain the deposition and time course of spread of solution within the transversus abdominis fascial plane in vivo. Results: Cadaveric studies demonstrated that the injection of methylene blue via the triangle of Petit using the “double pop” technique results in reliable deposition into the transversus abdominis plane. In volunteers, the injection of local anesthetic and contrast produced a reliable sensory block, and demonstrated deposition throughout the transversus abdominis plane. The sensory block produced by lidocaine 0.5% extended from T7 to L1, and receded over 4 to 6 hours, and this finding was supported by magnetic resonance imaging studies that showed a gradual reduction in contrast in the transversus abdominis plane over time. Conclusions: These findings define the anatomic characteristics of the transversus abdominis plane block, and underline the clinical potential of this novel block.

Carbon dioxide and the critically ill--too little of a good thing?

Permissive hypercapnia (acceptance of raised concentrations of carbon dioxide in mechanically ventilated patients) may be associated with increased survival as a result of less ventilator-associated lung injury. Conversely, hypocapnia is associated with many acute illnesses (eg, asthma, systemic inflammatory response syndrome, pulmonary oedema), and is thought to reflect underlying hyperventilation. Accumulating clinical and basic scientific evidence points to an active role for carbon dioxide in organ injury, in which raised concentrations of carbon dioxide are protective, and low concentrations are injurious. We hypothesise that therapeutic hypercapnia might be tested in severely ill patients to see whether supplemental carbon dioxide could reduce the adverse effects of hypocapnia and promote the beneficial effects of hypercapnia. Such an approach could also expand our understanding of the pathogenesis of disorders in which hypocapnia is a constitutive element.

A comparison of tracheal intubation using the Airtraq or the Macintosh laryngoscope in routine airway management: A randomised, controlled clinical trial.

The Airtraq® laryngoscope is a novel single use tracheal intubation device. We compared the Airtraq® with the Macintosh laryngoscope in patients deemed at low risk for difficult intubation in a randomised, controlled clinical trial. Sixty consenting patients presenting for surgery requiring tracheal intubation were randomly allocated to undergo intubation using a Macintosh (n = 30) or Airtraq® (n = 30) laryngoscope. All patients were intubated by one of four anaesthetists experienced in the use of both laryngoscopes. No significant differences in demographic or airway variables were observed between the groups. All but one patient, in the Macintosh group, was successfully intubated on the first attempt. There was no difference between groups in the duration of intubation attempts. In comparison to the Macintosh laryngoscope, the Airtraq® resulted in modest improvements in the intubation difficulty score, and in ease of use. Tracheal intubation with the Airtraq® resulted in less alterations in heart rate. These findings demonstrate the utility of the Airtraq® laryngoscope for tracheal intubation in low risk patients.

Comparison of Macintosh, Truview EVO2®, Glidescope®, and Airwayscope® laryngoscope use in patients with cervical spine immobilization

BACKGROUND The purpose of this study was to evaluate the effectiveness of the Pentax AWS, Glidescope, and the Truview EVO2, in comparison with the Macintosh laryngoscope, when performing tracheal intubation in patients with neck immobilization using manual in-line axial cervical spine stabilization. METHODS One hundred and twenty consenting patients presenting for surgery requiring tracheal intubation were randomly assigned to undergo intubation using a Macintosh (n=30), Glidescope (n=30), Truview EVO2 (n=30), or AWS (n=30) laryngoscope. All patients were intubated by one of the three anaesthetists experienced in the use of each laryngoscope. RESULTS The Glidescope, AWS, and Truview EVO2 each reduced the intubation difficulty score (IDS), improved the Cormack and Lehane glottic view, and reduced the need for optimization manoeuvres, compared with the Macintosh. The mean IDS was significantly lower with the Glidescope and AWS compared with the Truview EVO2 device, and the IDS was lowest with the AWS. The duration of tracheal intubation attempts was significantly shorter with the Macintosh compared with the other devices. There were no differences in success rates between the devices tested. The AWS produced the least haemodynamic stimulation. CONCLUSIONS The Glidescope and AWS laryngoscopes required more time but reduced intubation difficulty and improved glottic view over the Macintosh laryngoscope more than the Truview EVO2 laryngoscope when used in patients undergoing cervical spine immobilization.

Permissive hypercapnia — role in protective lung ventilatory strategies

Abstract‘Permissive hypercapnia’ is an inherent element of accepted protective lung ventilation. However, there are no clinical data evaluating the efficacy of hypercapnia per se, independent of ventilator strategy. In the absence of such data, it is necessary to determine whether the potential exists for an active role for hypercapnia, distinct from the demonstrated benefits of reduced lung stretch. In this review, we consider four key issues. First, we consider the evidence that protective lung ventilatory strategies improve survival and we explore current paradigms regarding the mechanisms underlying these effects. Second, we examine whether hypercapnic acidosis may have effects that are additive to the effects of protective ventilation. Third, we consider whether direct elevation of CO2, in the absence of protective ventilation, is beneficial or deleterious. Fourth, we address the current evidence regarding the buffering of hypercapnic acidosis in ARDS. These perspectives reveal that the potential exists for hypercapnia to exert beneficial effects in the clinical context. Direct administration of CO2 is protective in multiple models of acute lung and systemic injury. Nevertheless, several specific concerns remain regarding the safety of hypercapnia. At present, protective ventilatory strategies that involve hypercapnia are clinically acceptable, provided the clinician is primarily targeting reduced tidal stretch. There are insufficient clinical data to suggest that hypercapnia per se should be independently induced, nor do outcome data exist to support the practice of buffering hypercapnic acidosis. Rapidly advancing basic scientific investigations should better delineate the advantages, disadvantages, and optimal use of hypercapnia in ARDS.