Areti Y. Kumar

Capnometry and anaesthesia

In the last decade, capnography has developed from a research instrument into a monitoring device considered to be essential during anaesthesia to ensure patient safety. Hence, a comprehensive understanding of capnography has become mandatory for the anaesthetist in charge of patients in the operating room and in the intensive care unit. This review of capnography includes the methods available to determine carbon dioxide in expired air, and an analysis of the physiology of capnograms, which are followed by a description of the applications of capnography in clinical practice. The theoretical backgrounds of the effect of barometric pressure, water vapour, nitrous oxide and other factors introducing errors in the accuracy of CO2 determination by the infra-red technique, currently the most popular method in use, are detailed. Physiological factors leading to changes in end-tidal carbon dioxide are discussed together with the clinical uses of this measurement to assess pulmonary blood flow indirectly, carbon dioxide production and adequacy of alveolar ventilation. The importance of understanding the shape of the capnogram as well as end-tidal carbon dioxide measurements is emphasized and its use in the early diagnosis of adverse events such as circuit disconnections, oesophageal intubation, defective breathing systems and hypoventilation is highlighted. Finally, the precautions required in the use and interpretation of capnography are presented with the caveat that although no instrument will replace the continuous presence of the attentive physician, end-tidal carbon dioxide monitoring can be effective in the early detection of anaesthesia-related intraoperative accidents.RésuméLa capnographie est maintenant un élément essentiel du monitorage des patients pendant l’anesthésie générate et tout anesthésiste doit comprendre les principes de fonctionnement de cette technique. La présente révision décrit les méthodes disponibles de mesure de gaz carbonique (CO2) expiré, ainsi qu ’une analyse de la physiologie associée aux différents capnogrammes. Une description des applications cliniques de la capnographie fait suite à ces énoncés théoriques. Les effets de la pression barométrique, de la vapeur d’eau, du protoxide d’azote et de plusieurs autres facteurs affectant la mesure du CO2 a l’aide d’infra-rouge sont décrits. La capnographie permet une mesure indirecte de la circulation pulmonaire, de la production de CO2 et de la ventilation alveolaire. Ces mesures sont influencees par de nombreux facteurs physiologiques qu ’il importe de bien connaître afin de déterminer les limites de ce monitorage. Une bonne interprétation de la forme des cburbes de capnographie est nécessaire afin de permettre la détection précoce d’incidents dangereux tels un défaut ou débranchement du circuit anesthésique, une intubation oesophagienne ou une hypoventilation. Le présent travail permet à l’anesthésiste de revoir toutes ces notions et rappelle que même si la capnographie ne remplace pas la vigilance du clinicien, elle peut permettre la détection rapide d’événements qui pourraient mener à des complications anesthésiques.

A new tool for measurement of process‐based performance of multispecialty tertiary care hospitals

There is an increasing need of a model for the process-based performance measurement of multispecialty tertiary care hospitals for quality improvement. Analytic hierarchy process (AHP) is utilized in this study to evolve such a model. Each step in the model was derived by group-discussions and brainstorming sessions among experienced clinicians and managers. This tool was applied to two tertiary care teaching hospitals in Barbados and India. The model enabled identification of specific areas where neither hospital performed very well, and helped to suggest recommendations to improve those areas. AHP is recommended as a valuable tool to measure the process-based performance of multispecialty tertiary care hospitals.

Terminology and the current limitations of time capnography: A brief review

The carbon dioxide (CO2) trace versus time (time capnography) is convenient and adequate for clinical use. This is the method most commonly utilized in capnography. However, the current terminology in time capnography has not yet been standardized and is, therefore, a potential source of confusion. Standard terminology that is based on convention and logic to represent the various phases of a time capnogram is essential. The time capnogram should be considered as two segments: an inspiratory segment and an expiratory segment. The inspiratory segment is termed as phase 0; the expiratory segment is divided into phases I, II, III, and, occasionally, IV, Phase I represents the CO2-free gas from the airways (anatomical dead space); phase II consists of a rapid S-shaped upswing on the tracing due to mixing of dead space gas with alveolar gas; and phase III, the alveolar plateau, represents CO2-rich gas from the alveoli. The physiologic basis of phase IV, the terminal upswing at the end of phase III, which is observed in capnograms recorded under certain circumstances (such as in pregnant subjects and obese subjects) is discussed in detail. The clinical implications of the alpha angle, which is the angle between phases II and III, and the beta angle, which is the angle between phases III and the descending limb of phase 0, are outlined. The subtle but important limitations of time capnography are reviewed; its current status as well as its future potential are explored.

The Effect of Preemptive Analgesia in Postoperative Pain Relief—A Prospective Double-Blind Randomized Study

OBJECTIVE To analyze the effect of infiltration of local anesthetics on postoperative pain relief. DESIGN Prospective randomized double-blind trial. Setting. University Teaching Hospital in Barbados, West Indies. PATIENTS Patients undergoing total abdominal hysterectomy. Interventions. Patients were randomly allocated into one of four groups according to the wound infiltration: 1) preoperative and postoperative 0.9% saline; 2) preoperative saline and postoperative local anesthetic mixture (10 mL 2% lidocaine added to 10 mL 0.5% bupivacaine); 3) preoperative local anesthetic mixture and postoperative saline; and 4) preoperative and postoperative local anesthetic mixture. Both patients and investigators were blinded to the group allocation. All patients received pre-incision tenoxicam and morphine, standardized anesthesia, and postoperative morphine by patient-controlled analgesia. Outcome measures. The amount of morphine used and the intensity of pain as measured by visual analog pain scale were recorded at 1, 2, 3, 4, 8, 12, 24, and 48 hours postoperatively. RESULTS Eighty patients were studied with 20 in each group. Total dose of morphine used by patients who received preoperative and postoperative local anesthetic infiltration was lesser compared to other groups, although there was no statistically significant difference. Similarly, there was no difference in the intensity of pain between any groups. CONCLUSIONS Local anesthetic infiltration before and/or after abdominal hysterectomy does not reduce the intensity of postoperative pain and analgesic requirements.

Futility-of-care decisions in the treatment of moribund intensive care patients in a developing country

PurposeTo analyze the characteristics of moribund patients in a surgical intensive care unit (ICU) and highlight the dilemmas inherent in treating such patients.MethodsData on all patients admitted to the surgical ICU during the period of three years from July 1999 to June 2002 were collected prospectively. Data were collected on very ill patients who died, in whom it appeared obvious that treatment could not have improved their condition and whose death could have been anticipated. The case notes were subjected to further analysis to determine the difficulties encountered in managing patients whose therapy was considered to be futile.ResultsOf 662 admissions, 100 (15.1%) died and 30 (4.5%) patients were treated aggressively, even after a prognosis which reflected futile treatment. The overall mean length of stay for survivors was 7.5 ± 9.0 [standard deviation (SD)] days and that for the non-survivors was 12.8 ± 18.1 (SD;P < 0.001). The cost incurred for the treatment of non-survivors was significantly higher than that for the surviving patients. The factors relating to the decisions to continue futile therapy were age of the patient, legal considerations, family wishes and differing opinions between treating physicians.ConclusionConsideration of futility during end-of-life care did not receive adequate attention in this unit which incurred additional human and material resources.RésuméObjectifAnalyser les caractéristiques des patients moribonds d’une unité de soins intensifs chirurgicaux (USI) et souligner les dilemmes inhérents au traitement de ces patients.MéthodeNous avons rassemblé prospectivement les données concernant tous les patients admis à l’USI chirurgicaux de juillet 1999 à juin 2002. Nous avons gardé les données sur des patients gravement malades qui sont décédés, pour qui il est apparu évident que le traitement n’avait pas amélioré la condition et dont la mort pouvait être prévue Les informations ont été ensuite soumises à une analyse supplémentaire afin de préciser les difficultés de prise en charge de ces patients dont le traitement était considéré inutile.RésultatsDes 662 patients admis, 100 (15,1 %) sont décédés et 30 (4,5 %) ont reçu un traitement énergique, même après un pronostic qui révélait l’inutilité du traitement. La moyenne globale de la longueur du séjour hospitalier des survivants a été de 7,5 ± 9,0 jours [écart type] et celle des non survivants a été de 12,8 ± 18,1 jours (écart type; P < 0,001). Le coût du traitement des non survivants a été significativement plus élevé que celui des survivants. Les facteurs qui ont amené à poursuivre un traitement inutile étaient l’âge du patient, des préoccupations légales, des demandes de la famille et des divergences d’opinions entre les médecins traitants.ConclusionOn ne se préoccupe pas suffisamment de l’inutilité des soins aux personnes en fin de vie à l’USI chirurgicaux, ce qui entraîne l’utilisation de ressources humaines et matérielles supplémentaires.

Should air-oxygen replace nitrous oxide-oxygen in general anaesthesia?

The use of compressed air‐oxygen mixtures to replace nitrous oxide‐oxygen in general anaesthesia was investigated in 378 patients. There were neither prolongations of recovery time nor instances of awareness under anaesthesia. The cost of general anaesthesia using compressed air‐oxygen was about half that for nitrous oxide‐oxygen mixtures.

Do Sedation and Neuromuscular Blockade Influence the Outcome of Adult Intensive Care Patients? A Prospective Observational Study

A prospective observational study was conducted on patients admitted to an adult intensive care unit (ICU) to investigate the pattern of sedation, analgesia and neuromuscular blockade and to determine their relationship to patient outcomes. Data including age, gender, diagnoses, dosage of sedatives, analgesics and neuromuscular blocking agents (NMBA), duration of mechanical ventilation, admission and weaning sedation scores, ICU length of stay and outcomes were recorded; 1550 patient-days were studied from 140 mechanically ventilated patients, of which 52 (37%) received NMBA. The mean length of stay in patients receiving NMBA was 15.6 days compared to 11.7 in patients who did not receive them (p=0.08). Mean duration of mechanical ventilation was 12.5 days in patients receiving NMBA, while it was 10.2 days in patients who did not receive NMBA (p=0.21). Neuromuscular blockade did not significantly influence the duration of mechanical ventilation, length of stay and survival of ICU patients.

Anesthesia outside the operating room for emergency procedures.

Non-anesthetists usually provide sedation and anesthesia outside the operating room for emergency procedures. Techniques vary from no sedation to deep sedation using drugs with a good safety profile and few side effects. Newer methods of airway control may allow volatile agents such as sevoflurane to be used. Anesthetists may need to join sedation teams if they are to maintain control of their specialty.