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Biomedical subjects

J H Waters

Publications and source records attributed to J H Waters.

At least 19 recordsLinked to original sources
PubMed2006

I.V. infusion of a drag-reducing polymer extracted from aloe vera prolonged survival time in a rat model of acute myocardial ischaemia.

BACKGROUND: I.V. infusion of drag-reducing polymers (DRPs) has been shown to improve survival time in animals subjected to haemorrhagic shock. We hypothesized that DRPs might prolong survival time in rats following acute myocardial ischaemia (AMI). METHODS: Sixteen adult male rats were anaesthetized and mechanically ventilated. An i.v. infusion of either Dextran-40 2.5% (Control, n=8) or Dextran-40 2.5% containing 50 microg ml(-1) of an aloe vera-based DRP (DRP, n=8) was initiated at 3.5 ml h(-1). The left anterior descending coronary artery was ligated. Blood pressure, skin-tissue perfusion, and heart rate were monitored and arterial blood samples were analysed. RESULTS: The mortality at 60 min following coronary ligation was 0% in the DRP group vs 50% in the control group (P=0.025). DRP-treated animals maintained higher mean arterial pressure [60.9 (5.1) vs 47.5 (5.1) mm Hg, P=0.004] and tissue perfusion [4.2 (3.4) vs 1.2 (0.5) TPU, P=0.029]. The DRP group trended towards better acid-base status with base excess [-5.0 (1.7) vs -8.1 (5.1) mmol litre(-1), P=0.083] and pH [7.42 (0.07) vs 7.35 (0.02), P=0.03]. CONCLUSIONS: Administration of nanomolar concentrations of aloe vera-based DRP prolonged survival time in animals with AMI. DRPs may offer a novel method to treat organ/tissue hypoperfusion.

Acute Disease↗
PubMed2006

A comparison of three facemasks used during the induction of general anaesthesia.

BACKGROUND AND OBJECTIVE: A prospective crossover randomized trial was conducted to compare the performance of three commonly used anaesthetic facemasks: a clear plastic 'Anaesthetic Facemask' with pre-inflated air cushion, no inflation valve, and for single use (Intersurgical Limited, Wokingham, UK), a clear plastic 'Air Cushion Mask' with inflatable air cushion and inflation valve, and for single use (Proact Medical Limited, Kettering, UK), and a black antistatic reusable rubber facemask with pre-inflated air cushion, and no inflation valve (Datex Ohmeda Limited, Hatfield, UK). METHODS: After local Ethics Committee approval, written consent was taken from 60 ASA 1 or 2 patients undergoing elective ENT procedures. Following routine intravenous anaesthetic induction and muscle relaxation, a Guedel's oropharyngeal airway was inserted and each of the facemasks tried in a crossover fashion. The degree of chest expansion, the feel on the reservoir bag, the degree of leak around the mask and the overall satisfaction of the anaesthetist were graded and recorded for each facemask. RESULTS: Both the plastic facemasks performed similarly in all the four criteria. The antistatic rubber facemask performed significantly better than the plastic facemasks in these criteria (P < 0.05). CONCLUSIONS: This study has shown that the antistatic rubber facemask outperformed the two plastic facemasks during routine induction of general anaesthesia. We hope this will encourage manufacturers to improve disposable facemask design to simulate the antistatic rubber facemask.

Adolescent↗
PubMed2006

Anesthetic management for emergency cesarean section in a patient with severe valvular disease and preeclampsia.

Wider selection of young patients for prosthetic valve replacement for valvular heart disease has resulted in an increase in number of women with heart disease reaching childbearing age. Such patients presenting in labor for emergency cesarean section require special consideration. We present a report of a parturient who presented at 36 weeks of gestation with severe aortic and mitral stenosis, pulmonary edema and severe preeclampsia. The goals of our anesthetic management included (1) careful airway management (2) maintaining stable hemodynamics (3) optimizing fluid status, and (4) preventing seizures. Issues related to management of patients with severe valvular disease, prosthetic valves and complications due to anticoagulant therapy during pregnancy are discussed.

Adult↗
PubMed2001

Outcome of adult cardiopulmonary resuscitations at a tertiary referral center including results of "limited" resuscitations.

BACKGROUND: The results of in-hospital resuscitations may depend on a variety of factors related to the patient, the environment, and the extent of resuscitation efforts. We studied these factors in a large tertiary referral hospital with a dedicated certified resuscitation team responding to all cardiac arrests. METHODS: Statistical analysis of 445 prospectively recorded resuscitation records of patients who experienced cardiac arrest and received advanced cardiac life support resuscitation. We also report the outcomes of an additional 37 patients who received limited resuscitation efforts because of advance directives prohibiting tracheal intubation, chest compressions, or both. MAIN OUTCOME MEASURES: Survival immediately after resuscitation, at 24 hours, at 48 hours, and until hospital discharge. RESULTS: Overall, 104 (23%) of 445 patients who received full advanced cardiac life support survived to hospital discharge. Survival was highest for patients with primary cardiac disease (30%), followed by those with infectious diseases (15%), with only 8% of patients with end-stage diseases surviving to hospital discharge. Neither sex nor age affected survival. Longer resuscitations, increased epinephrine and atropine administration, multiple defibrillations, and multiple arrhythmias were all associated with poor survival. Patients who experienced arrests on a nursing unit or intensive care unit had better survival rates than those in other hospital locations. Survival for witnessed arrests (25%) was significantly better than for nonwitnessed arrests (7%) (P =.005). There was a disproportionately high incidence of nonwitnessed arrests during the night (12 AM to 6 AM) in unmonitored beds, resulting in uniformly poor survival to hospital discharge (0%). None of the patients whose advance directives limited resuscitation survived. CONCLUSIONS: Very ill patients in unmonitored beds are at increased risk for a nonwitnessed cardiac arrest and poor resuscitation outcome during the night. Closer vigilance of these patients at night is warranted. The outcome of limited resuscitation efforts is very poor.

Adult↗
PubMed2001

Normal saline versus lactated Ringer's solution for intraoperative fluid management in patients undergoing abdominal aortic aneurysm repair: an outcome study.

UNLABELLED: Metabolic acidosis and changes in serum osmolarity are consequences of 0.9% normal saline (NS) solution administration. We sought to determine if these physiologic changes influence patient outcome. Patients undergoing aortic reconstructive surgery were enrolled and were randomly assigned to receive lactated Ringer's (LR) solution (n = 33) or NS (n = 33) in a double-blinded fashion. Anesthetic and fluid management were standardized. Multiple measures of outcome were monitored. The NS patients developed a hyperchloremic acidosis and received more bicarbonate therapy (30 +/- 62 mL in the NS group versus 4 +/- 16 mL in the LR group; mean +/- SD), which was given if the base deficit was greater than -5 mEq/L. The NS patients also received a larger volume of platelet transfusion (478 +/- 302 mL in the NS group versus 223 +/- 24 mL in the LR group; mean +/- SD). When all blood products were summed, the NS group received significantly more blood products (P = 0.02). There were no differences in duration of mechanical ventilation, intensive care unit stay, hospital stay, and incidence of complications. When NS was used as the primary intraoperative solution, significantly more acidosis was seen on completion of surgery. This acidosis resulted in no apparent change in outcome but required larger amounts of bicarbonate to achieve predetermined measurements of base deficit and was associated with the use of larger amounts of blood products. These changes should be considered when choosing fluids for surgical procedures involving extensive blood loss and requiring extensive fluid administration. IMPLICATIONS: Predominant use of 0.9% saline solution in major surgery has little impact on outcome as assessed by duration of mechanical ventilation, intensive care unit stay, hospital stay, and postoperative complications, but it does appear to be associated with increased perioperative blood loss.

Aged↗
PubMed2000

Prophylactic blood patch performed prior to continuous epidural analgesia.

Two cases of inadvertent dural puncture in patients at high risk for dural puncture headache are presented. These patients were managed with an immediate epidural blood patch through a catheter placed at another level with placement of this catheter occurring immediately following the dural puncture. Following the blood patch, the patients were anesthetized with the epidural catheter being used for supplementation of the general anesthetic and for postoperative pain management. Neither patient required further management of a dural puncture headache nor did it appear that the blood interfered with the patients receiving adequate postoperative analgesia through the use of this epidural catheter.

Adolescent↗
PubMed2000

Amniotic fluid removal during cell salvage in the cesarean section patient.

BACKGROUND: Cell salvage has been used in obstetrics to a limited degree because of a fear of amniotic fluid embolism. In this study, cell salvage was combined with blood filtration using a leukocyte depletion filter. A comparison of this washed, filtered product was then made with maternal central venous blood. METHODS: The squamous cell concentration, lamellar body count, quantitative bacterial colonization, potassium level, and fetal hemoglobin concentration were measured in four sequential blood samples collected from 15 women undergoing elective cesarean section. The blood samples collected included (1) unwashed blood from the surgical field (prewash), (2) washed blood (postwash), (3) washed and filtered blood (postfiltration), and (4) maternal central venous blood drawn from a femoral catheter at the time of placental separation. RESULTS: Significant reductions in the following parameters were seen when the postfiltration samples were compared to the prewash samples (median [25th-75th percentile]): squamous cell concentration (0.0 [0.0-0.1 counts/high-powered field (HPF)] vs. 8.3 counts/HPF [4. 0-10.5 counts/HPF], P < 0.05); bacterial contamination (0.1 [0.0-0. 2] vs. 3.0 [0.6-7.7] colony-forming units (CFU)/ml, P < 0.01); and lamellar body concentration (0.0 [0.0-1.0] vs. 22.0 [18.5-29.5] thousands/microl, P < 0.01). No significant differences existed between the postfiltration and maternal samples for each of these parameters. Fetal hemoglobin was in higher concentrations in the postfiltration sample when compared with maternal blood (1.9 [1.1-2. 5] vs. 0.5% [0.3-0.7] ). Potassium levels were significantly less in the postfiltration sample when compared with maternal (1.4 [1.0-1.5] vs. 3.8 mEq/l [3.7-4.0]). CONCLUSIONS: Leukocyte depletion filtering of cell-salvaged blood obtained from cesarean section significantly reduces particulate contaminants to a concentration equivalent to maternal venous blood.

Adult↗
PubMed2000

Dilutional acidosis following hetastarch or albumin in healthy volunteers.

BACKGROUND: The intent of this study was to evaluate the impact of the commonly used colloids-hetastarch and albumin-on in vivo acid-base balance. From this evaluation, a better understanding of the mechanism of dilutional acidosis was expected. METHODS: In a prospective, randomized fashion, 11 healthy volunteers were administered 15 ml/kg hetastarch solution, 6%, or 15 ml/kg albumin, 5%, intravenously over 30 min. Four weeks later, the study subjects were administered the other colloid. Arterial blood gas and electrolyte parameters were measured at baseline and at 30, 60, 90, 120, 210, and 300 min after colloid administration. Pre- and postlaboratory values were compared within groups using a paired t test and a Wilcoxon signed rank test and between groups using repeated-measures analysis of variance and a Wilcoxon rank sum test. RESULTS: Thirty min after infusion, subjects who were administered hetastarch showed statistically significant changes (P < 0.05) in base excess (from 2.5 +/- 0.9 mEq/l to 0.7 +/- 1.1 mEq/l), HCO3- concentration (from 27 +/- 1.0 mEq/l to 25 +/- 1.3 mEq/l), Cl- concentration (from 108 +/- 2 mEq/l to 112 +/- 2 mEq/l), albumin concentration (from 4.4 +/- 0.2 g/dl to 3.5 +/- 0.5 g/dl), and arterial carbon dioxide tension (Paco2; from 40.8 +/- 2.3 mmHg to 39. 2 +/- 3.2 mmHg), whereas only the albumin concentration (from 4.4 +/- 0.2 g/dl to 4.8 +/- 0.6 g/dl) changed significantly in the albumin-treated group. CONCLUSIONS: Decreases in base excess were observed for 210 min after hetastarch administration but not after albumin. The mechanism for this difference is discussed.

Acidosis↗
PubMed1999

Cause of metabolic acidosis in prolonged surgery.

OBJECTIVE: The intraoperative development of metabolic acidosis is frequently attributed to hypovolemia, tissue hypoperfusion, and lactic acidosis. In this study, dilutional acidosis was evaluated as a possible mechanism for the routine development of intraoperative acidosis in noncardiac, nonvascular surgery patients. DESIGN: Prospective, observational study. SETTING: University-affiliated Veteran's Affairs Medical Center and a staff model, health maintenance organization hospital. PATIENTS: Twelve patients undergoing prolonged surgical procedures expected to last > or = 4 hrs were enrolled in the study. INTERVENTIONS: Perioperative management was based on the judgment of the attending anesthesiologist and surgeon without knowledge of the study's intent. MEASUREMENTS AND MAIN RESULTS: Arterial blood gas parameters, serum electrolytes, and urine electrolytes were measured pre- and postoperatively. Pulmonary artery catheters were placed for hemodynamic measurement and oxygen delivery calculations. Plasma volume was measured both pre- and postoperatively, using the Evans blue dye dilution technique. Although significant changes in lactate level (1.1 +/- 0.6-1.8 +/- 1.0) occurred, the change was not large enough to explain the degree of change in base excess (0.8 +/- 2.3 to -2.7 +/- 2.9). Chloride levels significantly increased (106 +/- 3-110 +/- 5) with a correlation (r2 = .92; p < .0001) between the degree of change in chloride and the degree of change in base excess. Plasma volume did not change. Furthermore, a correlation between the volume of normal saline administered and the change in base excess was found (r2 = .86; p < .0001), although no correlation was found with Ringer's lactate solution. An even stronger correlation was noted when the total chloride amount administered was compared with the change in base excess (r2 = .93; p < .0001). CONCLUSIONS: In this patient population, a common source of increasing base deficit is related to chloride administration. The largest source of chloride is usually normal saline. Classically, dilutional acidosis would explain the predominance of this acidotic change; however, no increase in plasma volume occurred. The absence of plasma volume change would suggest that the mechanism postulated to result in dilutional acidosis is incomplete. The common treatment of administering more fluid for intraoperative acidosis may be inappropriate, may have caused the acidosis, and may further exacerbate the acidosis. Chloride levels should be assessed whenever a metabolic acidosis is seen perioperatively.

Acidosis↗
PubMed1998

Considerations in placement of right internal jugular cannulas.

This case report describes a patient who had paroxysmal ventricular bigeminy of an unrecognized etiology. After 24 hours of observation, it was noted that the patient's head position correlated with the bigeminy. A single-lumen infusion catheter, which had been placed through an internal jugular cannula, was transduced and demonstrated a ventricular pressure waveform. This catheter was removed and the ectopy resolved. The factors associated with this arrhythmia are discussed.

Aged↗
PubMed1997

Patient and surgeon satisfaction with extremity blockade for surgery in remote locations.

In a practice that may be unique to military health care, extremity nerve blocks are established by anesthesiologists before transporting the patient to a remote clinic for surgery without further monitoring by anesthesia personnel. The safety and acceptance of this practice was assessed through a prospective survey of the surgeons and their patients. Six hundred seventy-seven blocks were performed in a 1-yr period with no adverse events related to this practice. Completed surveys were received from 406 (60%) of the surgeons and 232 (34%) of the patients. Of the blocks performed, 638 (94%) were brachial plexus blocks, with axillary blocks accounting for 87% of the brachial plexus blocks. Of the responding patients, 78% stated that they would be willing to undergo a repeat block. The surgeons were satisfied with the operating conditions in 96% of the cases. This study supports the safety and efficacy of this practice.

Adolescent↗