Intra-abdominal pressure measurements in lateral decubitus versus supine position

OBJECTIVE

Intra-abdominal pressure (IAP) has traditionally been measured in the supine position, however, measuring the pressure in lateral semi-recumbent position has not been studied.

DESIGN

A single centre prospective 1-day study.

PATIENTS

10 patients admitted for more then 24 hours who were mechanically ventilated and had an indwelling urinary catheter.

METHODS

Inclusion criteria included were age > 18 years, sedated to a RASS score of -5 and mechanically ventilated. The pressures were measured via the bladder with the mid-axillary line as zero reference point. When patients were nursed in lateral decubitus, pressures were measured and compared immediately to the supine position.

RESULTS

10 patients were included with a total of 60 measurements.The male/female ratio was 9:1 with a mean APACHE Pi score of 11.5 [95% CI 4.8-22.4], SAPS 2 of 31.5 [95% CI 8.9-35.8] and SOFA score of 4.0 [95% CI 1.8-7.2]. Four patients were medical and 6 were surgical. The mean IAP at different time intervals (morning, afternoon and evening) in lateral and supine position were 10.9 +/- 2.0 (in mmHg) vs 6.6 +/- 3.2 (SD with p < 0.001); 11.0 +/- 4.0 vs 5.4 +/- 2.2 (p < 0.0005) and 11.6 +/- 3.8 vs 7.8 +/- 3.0 (p< 0.001). Overall, the LSP did not change significantly (p= 0.76), but the SP did (p=0.006) with the afternoon reading being significantly lower than the evening measurement. However, the trend in the difference (LSP minus SP) was not significant (p=0.43).

CONCLUSION

There was a significant statistical difference in the pressures measured in LSP versus SP.The LSP position should not be used to measure IAP.

Sedation and Delirium in the Intensive Care Unit: An Australian and New Zealand Perspective

A survey was conducted to determine sedation and delirium practices in Australian and New Zealand intensive care units.

The survey was in two parts, comprising an online survey of reported sedation and delirium management (unit survey) and a collection of de-identified data about each patient in a unit at a given time on a specified day (patient snapshot survey). All intensive care units throughout Australia and New Zealand were invited by email to participate in the survey.

Twenty-three predominantly metropolitan, level III Australian and New Zealand intensive care units treating adult patients participated. Written sedation policies were in place in 48% of units, while an additional 44% of units reported having informal sedation policies. Seventy percent of units routinely used a sedation scale. In contrast, only 9% of units routinely used a delirium scale. Continuous intravenous infusion is the primary means of patient sedation (74% of units). While 30% of units reported routinely interrupting sedation, only 10% of sedated patients in the snapshot survey had had their sedation interrupted in the preceding 12 hours. Oversedation appears to be common (46% of patients with completed sedation scales). Use of neuromuscular blockade is low (10%) compared to other published studies. Midazolam and propofol were the most frequently used sedatives. The proportion of patients developing delirium was 21% of assessable patients. Failed and self-extubation rates were low: 3.2% and 0.5% respectively.

In Australian and New Zealand intensive care units, routine use of sedation scales is common but not universal, while routine delirium assessment is rare. The use of a sedation protocol is valuable and should be encouraged.

Amrinone versus dobutamine in cardiac surgical patients with severe pulmonary hypertension after cardiopulmonary bypass: a prospective, randomized double-blinded trial

We compared the relative effects of dobutamine (5 micrograms/kg/min) and amrinone (1.0 mg/kg bolus followed by 10 micrograms/kg/min) on right and left ventricular function and pulmonary arterial pressures during weaning from cardiopulmonary bypass in patients with a mean preoperative pulmonary pressure > 30 mmHg. Twenty patients scheduled for mitral valve replacement were studied in a prospective, randomized, double-blind trial. Patients receiving amrinone had a greater increase in cardiac index (CI) of 1.38 (+/-0.95) litre/min/m2 at separation vs 0.69 (+/-0.63) litre/min/m2 in the dobutamine group (P < 0.05). The amrinone group also had a greater increase in right ventricular ejection fraction (0.15 +/- 0.08 at separation from cardiopulmonary bypass versus an increase of 0.04 +/- 0.11 in those receiving dobutamine; P < 0.005). Amrinone produced a larger decrease in pulmonary artery wedge pressure 8.0 (+/-4.4) mmHg vs 0.75 (+/-6.6) mmHg at separation; pulmonary artery systolic and diastolic pressures also were reduced more in the amrinone group. There were no differences in heart rate, mean arterial pressure, central venous pressure and right ventricular stroke work index between patient groups. In the doses chosen, the use of amrinone compared to dobutamine was associated with a reduction in pulmonary arterial pressures and an increase in cardiac index and right ventricular ejection fraction after separation from bypass in patients with severe preoperative pulmonary hypertension.

Quantitative measurement of nasal production of nitric oxide in awake humans

The aim of this study was to determine, quantitatively, the production of nitric oxide (NO) in the nose and nasopharynx. Subjects were instructed to perform a Valsalva manoeuvre with their mouth open as gas was aspirated from a closely fitting nasal CPAP mask by a chemiluminescence analyser (Sievers 270B, Sievers Instrument Corp. Boulder, Colorado, U.S.A.). Room air was free to flow in through the mouth and out through the nose and hence to the analyser. The manoeuvre was continued until a smooth plateau of at least 20 seconds in duration was achieved on a chart recorder. The mean plateau concentrations were 176 (+/- 39.6) parts per billion (ppb) for males and 135.8 (+/- 24.4) ppb for females. The mean male production of NO was 15.8 nanomol/min which was significantly different from that of females of 12.5 nanomol/min (Mann-Whitney U Test; P < 0.01). By measuring the concentration of NO in gas aspirated from the nose during Valsalva manoeuvre, we excluded the respiratory tract below the glottis from our sampling and as such results represent the portion of NO produced in the nose and nasopharynx. These findings suggest that nasally produced NO is produced in sufficient quantities to act as a continuous pulmonary vasodilator, being inspired preferentially into areas of greatest ventilation, thus perhaps acting to continually match ventilation to perfusion.

The combination of mannitol and albumin in the priming solution reduces positive intraoperative fluid balance during cardiopulmonary bypass

During cardiopulmonary bypass (CPB) an adequate reservoir volume is maintained by the addition of crystalloid, colloid or packed cells to the reservoir. This volume contributes to the overall perioperative positive fluid balance. We studied the effect of the preoperative addition of either 75 g albumin, or 50 g mannitol followed by 50 g at commencement of rewarming or both of the above to a bypass circuit prime of lactated Ringer's solution (LR) on intraoperative fluid balance, postoperative indices of oxygenation and time to extubation. The study was a prospective, randomized, single-blinded controlled trial of 103 patients undergoing cardiac surgery requiring CPB. There was a large and highly significant reduction in volume of fluid added to the reservoir during CPB (2137 +/- 1499 ml versus 144 +/- 230 ml), the fluid balance during bypass, including prime volume (3236 +/- 650 ml versus 5876 +/- 1465 ml), and perioperative fluid balance (4470 +/- 936 ml versus 7023 +/- 1760 ml) in the group receiving both mannitol and albumin in the pump prime compared with the group receiving only lactated Ringer's solution. There were no differences between the groups with respect to both measured indices of oxygenation measured on return to ICU (alveolar-arterial oxygen tension difference (DA-aO2) or arterial oxygen tension to inspired oxygen fraction ratio (PaO2/FiO2), or time from ICU admission to extubation.

Boerhaave's syndrome complicated by a large bronchopleural fistula

We report a case Boerhaave's syndrome complicated by a large bronchopleural fistula due to autolysis of lung parenchyma by gastric contents, a complication not previously documented to our knowledge.

Death by tanning--a case of fatal basic chromium sulphate poisoning

A woman ingested 400 ml of leather tanning solution containing 48 g of basic chromium sulphate (CrOHSO4). This substance forms hydrogen ions and trivalent chromium when it reacts with tissue proteins. The patient died of cardiogenic shock, complicated by pancreatitis and gut mucosal necrosis and haemorrhage. There are no reported cases of toxicity due to oral ingestion of trivalent chromium. Toxicity of hexavalent and trivalent chromium is discussed and suggestions made for management of future cases.