Pulmonary function after laparoscopic cholecystectomy and abbreviated anesthetic-surgical time

Abstracts

OBJECTIVE: To evaluate pulmonary function after laparoscopic cholecystectomies. MEHTODS: Prospective study, in which the post-operative spirometries of 15 patients who underwent laparoscopic cholecystectomies with abbreviated anesthetic-surgical time were analyzed. RESULTS: Significant differences existed for the Forced Vital Capacity variable (p=0,020) and Forced Expiratory Volume in the first second (p=0,022) between pre- and immediate post-operative, indicating restrictive ventilatory disturbances. CONLCUSION: Light restrictive laparoscopic post-cholecystectomy ventilatory disturbances were observed, with rapid recovery of pulmonary function, which may lower post-operative pulmonary morbidity.

Lung; Respiratory function tests; Cholecystectomy; laparoscopic

OBJETIVO: Avaliar a função pulmonar pós-colecistectomias laparoscópicas. MÉTODOS: Estudo prospectivo, onde se avaliaram espirometrias pós-operatórias de 15 pacientes submetidas à colecistectomias laparoscópicas por meio de um tempo anestésico-cirúrgico abreviado. Os dados pós-operatórios foram comparados aos pré-operatórios RESULTADOS: Existiram diferenças significativas para as variáveis Capacidade Vital Forçada (p=0,020) e Volume Expiratório Forçado no 1º segundo (p=0,022) no pré e pós-operatório imediato, indicando distúrbios ventilatórios restritivos. CONCLUSÃO: Foram observados distúrbios ventilatórios restritivos leves pós-colecistectomias laparoscópicas, com rápida recuperação da função pulmonar, o que pode diminuir a morbidade pulmonar pós-operatória.

Pulmão; Testes de função respiratória; Colecistectomia laparoscópica

ORIGINAL ARTICLES

Pulmonary function after laparoscopic cholecystectomy and abbreviated anesthetic-surgical time

Gilson Cassem Ramos^I; Edísio Pereira^II; Salustiano Gabriel Neto - TCBC-GO^III; Enio Chaves de Oliveira - TCBC-GO^IV

^IMD, Universidade de Brasília (UnB), Distrito Federal, Brazil

^IIPhD, Professor, Graduate Program of the School of Health Sciences of the UnB, Distrito Federal, Brazil

^IIIAssistant Professor, Operative Technique, School of Medicine of the Universidade Federal de Goiás (UFG), GO, Brazil

^IVPhD, Professor, Coloproctology, School of Medicine of the UFG, GO, Brazil

Correspondence address

ABSTRACT

OBJETIVE: To evaluate pulmonary function after laparoscopic cholecystectomies.

METHODS:Prospective study in which the postoperative spirometries of 15 patients who underwent laparoscopic cholecystectomies with reduced anesthetic and surgical time were analyzed.

RESULTS: Significant differences were found for the Forced Vital Capacity variable (p=0.020) and Forced Expiratory Volume in the first second (p=0.022) between the pre- and immediate postoperative periods, indicating restrictive ventilatory dysfunction.

CONCLUSION: Light restrictive laparoscopic post-cholecystectomy, ventilator disturbances were observed, with rapid recovery of pulmonary function, wich may lower postoperative pulmonary morbidity.

Key words: Lung/physiology. Respiratory function tests. Cholecystectomy, laparoscopic.

INTRODUCTION

Upper abdominal operations may induce postoperative restrictive ventilatory defects. They are more pronounced in open procedures, yet also seen in laparoscopic ones¹. Even by the latter route, those operations produce, albeit to a lesser extent, an inhibitory reflex of the phrenic nerve and diaphragm dysfunction^2,3. In the past, laparoscopic cholecystectomies promoted major decreases in Forced Vital Capacity (FVC) and Forced Expiratory Volume in the first second (FEV₁), similar to what was observed with the open route⁴. However, faster recovery of postoperative pulmonary function was expected. With the mastery of the laparoscopic technique, this has undoubtedly become the technique of choice for cholecystectomies – although it can also impair postoperative pulmonary function.

The objective of this study was to detect restrictive ventilatory defects, their severity and the recovery time of spirometry measurements in the postoperative period of laparoscopic cholecystectomies as compared to the preoperative (baseline) values.

METHODS

This study was conducted with patients who sought the Digestive Tract Surgery Service at the Hospital Ortopédico de Goiânia, GO, Brazil. It was approved by the Research Ethics Committee of the Hospital de Urgências de Goiânia, and the informed consent document was signed by the patients enrolled in the study.

The study was comprised of 15 randomly chosen women with ages between 21 and 65 years, BMI lower or equal to 35, ASA (American Society of Anesthesiologists) grade I or II, with normal preoperative spirometry, arterial blood gas measurements and chest radiographs, who were undergoing cholecystectomy without intraoperative cholangiography. Excluded were patients using bronchodilator drugs; smokers; patients whose height could not be precisely determined (kyphoscoliosis, lower limb amputation, bedridden patients); pregnant women; patients with respiratory diseases; acute abdomen or a past medical history of colon diverticulum disease; patients with a history of gastroduodenal ulcer, gastrointestinal hemorrhage; neuromuscular disease patients; psychiatric patients; patients with contraindications to epidural anesthetic block; and those with a clinical history of allergy to dipyrone, diclofenac sodium or to the anesthetics selected to be used in the study.

This was a prospective study in which the patients were followed-up postoperatively for pulmonary function evaluation. The patients underwent cholecystectomy by the laparoscopic route under epidural block associated with general anesthesia, following a standardized anesthetic protocol; all anesthetic procedures were always performed by the same anesthesiologist. The patients underwent intubation orotracheal with the insertion of a 7.5-mm cannula and insufflation of the cuff with 5 mL of air. Anesthesia was maintained with isoflurane (0.5% to 1%) and N₂O, in a 50% mixture with O₂. Intubation was timed from the moment when the lower end of the cannula passed through the vocal cords to the moment of orotracheal extubation, a procedure that was indcated when the patient exhibited clinically satisfactory respiratory amplitude and rate. The values, in minutes, for intubation length were rounded to integers such that the difference between the adopted value in the study and the actual duration of the procedure was no greater than 30 seconds. Any procedure whose anesthetic and surgical time was longer than 50 minutes, including orotracheal extubation, was excluded from the study and a new patient was selected to compose the group. Intravenous 2 g dipyrone and intramuscular 75 mg diclofenac sodium were administered 6-hourly and 12-hourly, respectively, starting when the patient was discharged from the recovery room.

The patients were all operated on by the same surgeon using the same surgical technique⁵. They were placed in supine and an incision was made at the upper edge of the umbilical scar, comprising skin and subcutaneous. A 10-mm trocar was inserted, thus initiating CO₂ insufflation. Once pneumoperitoneum was established (maintained at a pressure around 13 mmHg), the camera was inserted and, under direct visualization, additional trocars were inserted in the peritoneal cavity: one 10-mm trocar in the subxiphoid region and two 5-mm trocars in the right subcostal region, in the midclavicular line and in the anterior axillary line. The procedure was performed by dissecting the peritoneum off the neck of the gallbladder and the cystic duct. Following the identification of the cystic artery and duct, the clipping and section of those structures was performed. Excision of the gallbladder was achieved by sectioning the peritoneum and adventitia between the liver and the gallbladder. Hemostasis was achieved using an electrocautery. The gallbladder was removed through the subxiphoid orifice and the skin was sutured. Operative time was defined in minutes, using the same rounding method used to obtain intubation time span. The beginning of the operation corresponded to the moment of the skin incision, and the end, the last stitch of the skin suture.

The patients underwent serial spirometric measurements. The first test was carried out preoperatively. The second, within the first 24 postoperative hours. Thereafter, new spirometries were undertaken every two days until a test considered to be normal for the patient was obtained, at which time testing was concluded. The spirometries were always conducted by the same professional – a respiratory function technician – with the same equipment: a portable spirometer Spiro Pro^® version 2.0, which can measure pulmonary flow and volume parameters and is validated by the American Thoracic Society (ATS). The device, in addition to generating flow-volume and volume-time curves, discriminated 12 spirometric variables and the results were printed out automatically. The parameters were analyzed on the basis of Knudson's regression equation⁶. Preparation for each spirometry session included calibrating the spirometer through an appropriate calibration syringe, adjusted to ambient temperature (25ºC to 40ºC) and atmospheric pressure (680 mmHg).

Alcoholic and caffeine-containing drinks – such as tea, coffee, chocolate and cola beverages – were proscribed for the patients in the four to six hours prior to the test, for their bronchodilator effect⁷. The individual variables height (in cm), weight (in kg), female gender and date of birth were recorded and stored in the spirometer. After 10 minutes of rest in a calm environment, the patient was instructed to stay in a sitting position and focus her attention on the directions for the procedure, which was thoroughly described, with an emphasis on the need to avoid leaks around the disposable mouthpiece and the importance of maximal inspiration followed by rapid, potent (explosive) and sustained expiration until the test was halted. The nostrils were closed with a noseclip and the test was performed using a closed system. Each patient underwent three valid and reproducible tests. The device Spiro Pro^® version 2.0 uses the greatest value obtained from the equation FVC + FEV₁ to select the best test. The spirometry reports were always provided and interpreted by the same pneumologist, a specialist in lung function tests, blinded to the patients' clinical history. The variables FVC and FEV₁ were analyzed individually, pre- and postoperatively, up to the point when their values normalized (80 % of the precalculated theoretical value for FVC and FEV₁ ). The hypothesis that means between groups were equal before and after surgery was tested through Student's paired t-test⁸. The value of P<0.05 was considered statistically significant when evaluating differences between parameters.

RESULTS

Table 1 shows the demographic characterisics of the patients and operative variables.

Table 2 shows the variables FVC and FEV₁ from the preoperative assessment to the third postoperative day. Statistically significant differences occurred for both variables when preoperative and immediate postoperative values were compared (P=0.020 for FVC and P=0.022 for FEV₁). Table 3 shows individual values for each spirometric variable, pre- and postoperatively.

Figure 1 shows the decreases in spirometric variables FVC and FEV₁ in the preoperative and immediate postoperative period, while Figure 2 depicts the curves of the same spirometric variables from the preoperative period to the 3rd postoperative day.

DISCUSSION

In the present study, mild restrictive ventilatory defects were observed, with FVC and FEV₁ reduction, when these two variables were compared pre- and postoperatively. Therefore, laparoscopic cholecystectomy also results in postoperative spirometric changes, an observation that is in agreement with several other scientific journals^9,10. However, in the present study, the most pronounced decreases in FVC and FEV₁ were 8.2% and 8.4%, respectively, in relation to the baseline values. This implies that postoperative spirometric values are comparable to normal tests when compared with the predicted values.

No reports were found of scientific observations similar to those made in the present study. More marked alterations are usually found, even in laparoscopies, with decreases between 20% and 30%^11-13 in both variables or even more expressive reductions, greater than 40%⁴.

Diaphragm dysfunction is the major causative factor related to restrictive ventilatory defects after cholecystectomies^2,14,15 and also occurs in laparoscopic procedures^1,16. This dysfunction is independent of postoperative pain², lasts approximately one week, and is mediated by an afferent reflex mechanism of phrenic nerve inhibition¹⁵; the diaphragm shows no impaired contractility¹⁷. Another important factor in the genesis of ventilatory defects is postoperative pain, which also contributes to pulmonary function deterioration after upper abdominal surgical procedures¹⁸.

Other factors are also relevant as they exacerbate both diaphragm dysfunction and postoperative pain, and tend to impair pulmonary function. Among them are the duration of tissue aggression (extended operative time, longer than one or two hours), the size of the surgical incision, the injury of muscle fibers and intubation time longer than two hours^19,20.

Thus, in the present study, reduced diaphragm dysfunction and postoperative pain, a characteristic of laparoscopic procedures^21,22, along with shorter anesthetic and surgical time, were the main determinants for minimally altered or normal postoperative spirometric values in relation to the predicted values. All patients exhibited, in the immediate postoperative period, spirometry values that were considered to be normal, yet lower than those found in the preoperative period. Thus, the spirometric variables FVC and FEV₁ decreased in the immediate postoperative period when compared with the preoperative values, and in the following measurement (third postoperative day), values were already equivalent to those of the preoperative period. A number of studies pointed to the recovery of pulmonary function after laparoscopic cholecystectomy between 8 to 10 days^18,23, which finds no support in the present study. The difference is likely explained by the reduced operative time involving less tissue injury and diaphragm dysfunction.

Therefore, it could be concluded that pulmonary function after laparoscopic cholecystectomy with reduced anesthetic and surgical time tends to faster recovery, which could lessen postoperative pulmonary morbidity.

REFERENCES

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Publication Dates

• Publication in this collection
  09 Nov 2009
• Date of issue
  Aug 2009

History

• Received
  14 Nov 2008
• Accepted
  19 Jan 2009