Abhiram Mallick

Initial evaluation of diaspirin cross-linked hemoglobin (DCLHb) as a vasopressor in critically ill patients.

OBJECTIVE To evaluate the hemodynamic effects and any toxicologic effects of diaspirin cross-linked hemoglobin (DCLHb) in critically ill patients. DESIGN A prospective, observational study. SETTING A seven-bed intensive care unit (ICU) in a University teaching hospital. PATIENTS Fourteen critically ill patients requiring vasopressor therapy to maintain adequate mean arterial pressure (MAP). All patients had secondary organ dysfunction. INTERVENTIONS Administration of 100 mL boluses of 10% diaspirin cross-linked hemoglobin, up to a maximum of 500 mL, given over 15 mins and separated by 60 to 90 mins. MEASUREMENTS AND MAIN RESULTS Hemodynamic parameters, norepinephrine and inotropic requirements, arterial and mixed venous blood gases, urine output, and biochemical and hematologic analyses were measured before diaspirin cross-linked hemoglobin administration and at multiple time points up to 72 hrs. MAP was maintained at approximately preinfusion values and the reduction in norepinephrine requirements was used as the main end point to assess the efficacy of diaspirin cross-linked hemoglobin as a vasopressor. Diaspirin cross-linked hemoglobin demonstrated a marked vasopressor action, allowing norepinephrine requirements to be reduced from 0.29 +/- 0.15 (SD) microgram/kg/min to 0.15 +/- 0.14 and 0.07 +/- 0.10 microgram/kg/min after the first (at 1.5 hrs, p < .001) and last (at 7.5 hrs, p < .0001) boluses, respectively. These reductions in norepinephrine requirements were maintained at 24, 48, and 72 hrs (p < .01 at all time points). These hemodynamic changes began within 5 mins of starting the diaspirin cross-linked hemoglobin infusion. MAP, heart rate, central venous pressure, pulmonary artery occlusion pressure, mean pulmonary arterial pressure (MPAP), systemic vascular resistance index, and urine output did not demonstrate any significant changes from preinfusion values. Pulmonary vascular resistance index increased at 7.5 hrs despite nonsignificant increases in MPAP. Cardiac index and oxygen delivery index decreased significantly at 7.5 hrs and 24 hrs. Total plasma bilirubin increased significantly from baseline at 24 and 48 hrs, before returning to baseline values within 5 days. Platelet count was significantly reduced at 6 and 24 hrs. No other biochemical or hematologic analyses were altered significantly post diaspirin cross-linked hemoglobin. CONCLUSIONS This preliminary study demonstrated that diaspirin cross-linked hemoglobin is a potent vasopressor agent in critically ill patients with septicemic shock or systemic inflammatory response syndrome. This vasopressor characteristic of diaspirin cross-linked hemoglobin may have future clinical applications.

The current practice of tracheostomy in the United Kingdom: a postal survey.

A postal questionnaire was sent to 228 intensive care units throughout the United Kingdom to determine aspects of current tracheostomy practice. From the number of units responding (n = 178, 78%), the majority (n = 173, 97%) practised percutaneous tracheostomy as opposed to open surgical tracheostomy. The Blue Rhino single dilator was the most popular technique (n = 114, 64%). Percutaneous tracheostomy is increasingly carried out under bronchoscopic guidance (n = 148, 83%); however, there remains considerable variation in the timing of tracheostomy and only 61 units (34%) have set follow‐up procedures.

Pumpless extracorporeal carbon dioxide removal for life-threatening asthma.

Objective:To report the use of pumpless extracorporeal carbon dioxide removal in two cases of acute severe asthma. Design:Case reports. Setting:Adult general intensive care unit, Leeds General Infirmary, Leeds, UK. Patients:A 74-yr-old male and 52-yr-old female with life-threatening asthma developed progressive hypercapnia and severe acidosis that proved nonresponsive to all other therapies. Intervention:Initiation of extracorporeal arteriovenous carbon dioxide removal using the Novalung device (Novalung GmbH, Lotzenäcker 3, D-72379 Hechingen, Germany). Main Results:The addition of extracorporeal carbon dioxide removal to mechanical ventilation corrected hypercapnia and acidosis, allowing reduction of other supportive measures. In both cases, adequate gas exchange was maintained until their underlying condition improved sufficiently for device removal. The two patients were subsequently weaned from mechanical ventilation and made a full recovery. Conclusions:Extracorporeal carbon dioxide removal proved to be a valuable adjunct to mechanical ventilation and other medical treatment.

Tracheostomy in critically ill patients.

Tracheostomy is performed in about a quarter of ICU patients requiring prolonged mechanical ventilation, weaning from assisted ventilation, airway suction and airway protection. Tracheostomy improves patient comfort compared with standard intubation. Tracheostomy performed early upon ICU admission has not shown survival benefits. Percutaneous dilatational techniques are commonly used because the procedure can be performed at the bedside. Surgical tracheostomy is often reserved for cases with abnormal anatomy or failed percutaneous tracheostomy. It is not known which of the percutaneous techniques is safer in terms of perioperative complications. Ultrasound scanning of the neck and routine endoscopy during the procedure appear to reduce early complications. Decannulation is often delayed and an intensivist-led follow-up may facilitate timely removal of tracheostomy tubes in step down areas or wards.

Use of the Combitube for airway maintenance during percutaneous dilatational tracheostomy

The Combitube airway allows short‐term ventilation during cardiopulmonary resuscitation and can be useful in the management of the difficult airway. In a prospective observational study we assessed its use during percutaneous dilatational tracheostomy (PDT). Twenty‐one intensive care patients scheduled for elective PDT had their tracheal tube replaced by a Combitube airway retaining the same ventilator settings. Arterial blood gases, airway pressures, SpO2 and end‐tidal CO2 were measured as were the transmural pressures exerted by the Combitube cuffs. Combitube placement was successful in 20 of 21 patients although adequate ventilation was possible in only 17 (85%). There was no significant change in PaO2, SpO2, end‐tidal CO2, PaCO2 or mean airway pressure during Combitube ventilation. A high mean (SD) transmural pressure of 14.7 (5) kPa was exerted by the distal cuff. The Combitube provided a satisfactory alternative airway to the tracheal tube during performance of PDT in 85% of our patients. Potential problems associated with its use in intensive care patients are outlined.

Extracorporeal carbon dioxide removal using the Novalung® in a patient with intracranial bleeding

A neurosurgical patient who required repeated surgery for intracranial haematoma developed acute respiratory distress syndrome. Raised intracranial pressure proved difficult to manage whilst attempting to maintain optimal gas exchange. The resultant arterial partial pressure of carbon dioxide remained unacceptably high, and treatment by extracorporeal carbon dioxide removal was started. A pumpless arteriovenous interventional lung assist device (Novalung™) was connected from the right femoral artery to left femoral vein and reduced the arterial carbon dioxide, corrected the respiratory acidosis and enabled control of the intracranial pressure. Subsequently the requirements for both respiratory and cardiovascular support were reduced. The patient made a complete neurological recovery.

Remifentanil patient-controlled analgesia following cardiac surgery.

Background:  Remifentanil is increasingly used as a component of cardiac anaesthesia. Following cardiac surgery remifentanil is often substituted for alternative opioids on the intensive care unit. We were interested to evaluate postoperative continuation of remifentanil in the form of remifentanil patient control analgesia (RPCA) for those patients who received intraoperative remifentanil. The objectives of this study were to assess the safety, efficacy and feasibility of the RPCA.

An investigation into the length of standard tracheostomy tubes in critical care patients

A number of problems have been reported with the use of standard length tracheostomy tubes in adult critical care patients. We measured the depth from the skin surface to the tracheal wall and the angle of the tracheal stoma during percutaneous tracheostomy. In vitro measurements were also performed on standard tracheostomy tubes. Comparison of in vivo and in vitro dimensions demonstrated that standard length tracheostomy tubes are too short for the average critical care patient. We recommend that both the stomal and intratracheal lengths should be made longer by approximately 1 cm and tubes should be redesigned to an angle of 110–120° to allow optimal tracheal placement.

Bonfils semirigid endoscope for guidance during percutaneous tracheostomy

We report on the use of the Bonfils semirigid scope for endoscopic guidance during percutaneous dilational tracheostomy. Forty patients requiring percutaneous dilational tracheostomy on the General or Neurosurgical Intensive Care Unit were enrolled in this study. We used the ‘45 degree curved distal tip’ scope in the first 15 patients, evaluating its ease of use, optical quality of focus and image resolution as well as light intensity on a 10‐point scale. We evaluated straight and curved versions of it in another 15 and 10 patients, respectively. We examined the impact on ventilation and cardiovascular parameters. In all patients (n = 40) visualisation of the procedure was satisfactory. There were no clinically significant changes in ventilatory or cardiovascular parameters. The image quality for most patients received a score of 7–10. The Bonfils scope provides a practical alternative to flexible bronchoscopes in this setting.

Lidocaine is more efficient than the choice of propofol formulations to reduce incidence of pain on induction.

Background and objective: Propofol is associated with pain on injection. It is common practice to premix lidocaine with propofol prior to injection. Lipuro propofol, a propofol emulsified in medium‐ and long‐chain triglycerides, has been shown to reduce the intensity of injection pain compared to Diprivan®, although a number of studies report no reduction in overall incidence of pain. Methods: We conducted this randomized double‐blind trial to determine the extent of further pain reduction by adding lidocaine to Lipuro propofol. A total of 328 ASA I–III patients were randomized to one of four groups to receive Diprivan propofol (Group DP), Lipuro propofol (Group LP), Diprivan with lidocaine (Group DL) and Lipuro propofol with lidocaine (Group LL). The drug mixture was administered at a constant rate of 400 mL h−1 via a 20‐G cannula into a dorsal hand vein. Pain was assessed during induction and upon patient recovery, using a 10‐point visual analogue scale. Results: Both the incidence and severity of pain were found to be significantly lower with addition of lidocaine to Lipuro propofol (P < 0.0002) compared to Lipuro alone, Diprivan with or without the addition of lidocaine. Conclusion: Lidocaine added to Lipuro propofol makes induction of anaesthesia less painful compared to Lipuro propofol alone or Diprivan with lidocaine.